ID: 40819564
Title: Nuclear pore complex dysfunction drives TDP-43 pathology in ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron degeneration and pathological aggregation of TDP-43. While protein misfolding and impaired autophagy are established features, accumulating evidence highlights the nuclear pore complex (NPC)as a vulnerable, redox-sensitive hub in ALS pathogenesis. Here, we show that selective loss of NPC components, particularly the scaffold proteins NUP107 and NUP93, and FG-repeat-containing components-is a consistent finding across ALS postmortem spinal cord, SOD1^G93A and TDP-43 mutant mouse models, and human cell systems.CRISPR-mediated depletion of NUP107 in human cells triggers hallmark features of ALS pathology, including cytoplasmic TDP-43 mislocalization, increased phosphorylation, and autophagy dysfunction. Conversely, TDP-43 knockdown perturbs NPC composition, suggesting a reciprocal regulatory loop. Crucially, we demonstrate that oxidative stress exacerbated NPC subunit mislocalization and enhanced TDP-43 aggregation. Using oxime blotting and DNPH assays, we show that FG-repeat subunits of NPC were direct targets of redox-driven carbonylation, indicating that oxidative modifications compromise NPC integrity thuspotentially affecting nucleocytoplasmic transport. Our findings established NPC dysfunction as a redox-sensitive driver of TDP-43 pathology in ALS and highlight nucleocytoplasmic transport as a promising therapeutic axis. The susceptibility of long-lived NPC proteins to oxidative damage provides a mechanistic link between redox stress, proteostasis collapse, and neurodegeneration.

ID: 41046022
Title: TDP-43 in Alzheimer's disease: Pathophysiology and therapeutic strategies.
Abstract: Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by the dysregulation of multiple molecular mechanisms. In recent years, transactive response DNA-binding protein 43 kDa (TDP-43) has increasingly been recognized as a critical pathological protein and has become a prominent focus in AD research. TDP-43 is involved not only in physiological processes such as RNA metabolism, protein quality control, and mitochondrial regulation but also in AD pathology through abnormal aggregation, dysregulated nucleocytoplasmic transport, and aberrant posttranslational modifications, leading to neurotoxicity, mitochondrial dysfunction, and disrupted protein homeostasis. Studies have shown that TDP-43 closely interacts with two core pathological hallmarks of AD, β-amyloid (Aβ) and tau. By promoting Aβ oligomerization and tau hyperphosphorylation, TDP-43 accelerates the pathological progression of this disease. Given the multifaceted role of TDP-43 in AD, therapeutic strategies targeting TDP-43 have shown great potential. Approaches such as modulating its RNA splicing activity, inhibiting pathological aggregation, restoring the balance of nucleocytoplasmic transport, and preventing its mitochondrial localization offer new avenues for AD treatment. This review systematically summarizes the pathological mechanisms of TDP-43 in AD and its interactions with Aβ and tau and discusses the feasibility of targeting TDP-43 as a therapeutic strategy. Future studies should further elucidate the role of TDP-43 in the early stages of AD and develop specific therapeutic agents that target TDP-43, with the aim of providing new insights for precision treatment of AD.

ID: 41174004
Title: TDP-43 skein-like inclusions are formed by BAG3- and HSP70-guided co-aggregation with actin-binding proteins.
Abstract: In multiple neurodegenerative diseases, the RNA-binding protein TDP-43 forms cytoplasmic aggregates of distinct morphologies, including skein-like, small rounded granular and large spherical inclusions. Here, whereas the N-terminal self-oligomerization domain regulates TDP-43 demixing into cytoplasmic droplets, inhibition of N-terminal self-oligomerization domain-mediated oligomerization is shown to promote the formation of skein-like inclusions. Utilizing proximity labelling-mass spectrometry, cellular stresses are shown to induce TDP-43 association with actin-binding proteins that include filamins and α-actinin. Small interfering RNA-mediated reduction of filamin in Drosophila ameliorates cell loss from cytoplasmic TDP-43, consistent with the filamin-TDP-43 interaction enhancing cytotoxicity. TDP-43's association with actin-binding proteins is mediated by BAG3, a HSP70 family nucleotide exchange factor that regulates the proteostasis of actin-binding proteins. BAG2, another HSP70 nucleotide exchange factor, facilitates the formation of small, rounded TDP-43 inclusions. We demonstrate that both TDP-43 self-oligomerization and its binding partners, including HSP70 and cochaperones BAG2 and BAG3, drive the formation of the different types of TDP-43 inclusion.

ID: 41174170
Title: TDP-43-dependent mis-splicing of KCNQ2 triggers intrinsic neuronal hyperexcitability in ALS/FTD.
Abstract: Motor neuron hyperexcitability is a broadly observed yet poorly understood feature of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Nuclear depletion and cytoplasmic aggregation of the RNA splicing protein TAR DNA-binding protein 43 (TDP-43) are observed in most ALS and FTD patients. Here we show that TDP-43 dysfunction causes mis-splicing of KCNQ2, which encodes a voltage-gated potassium channel (Kv7.2) that regulates neuronal excitability. Using iPSC-derived neurons and postmortem ALS/FTD brain and spinal cord tissue we find widespread, disease-specific and TDP-43-specific skipping of an exon encoding the KCNQ2 pore domain. The mis-spliced mRNA escapes degradation and is translated into a nonfunctional protein with severely reduced ion conductance that aggregates in the endoplasmic reticulum and causes intrinsic hyperexcitability in ALS neuronal models. This event, which correlates with higher phosphorylated TDP-43 levels and earlier age of disease onset in patients, can be rescued by splice-modulating antisense oligonucleotides that dampen hyperexcitability in induced pluripotent stem cell cortical neurons and spinal motor neurons with TDP-43 depletion. Our work reveals that nuclear TDP-43 maintains the fidelity of KCNQ2 expression and function and provides a mechanistic link between established excitability disruption in ALS/FTD patients and TDP-43 dysfunction.

ID: 41280089
Title: TDP-43 dysfunction leads to impaired proteostasis and predisposes mice to worse neurological outcomes after brain injury.
Abstract: Pathological TAR DNA-binding protein 43 (TDP-43) dysfunction is associated with multiple neurodegenerative disorders. However, the mechanistic link between TDP-43 dysfunction and neurodegeneration is poorly understood and likely involves a combination of genetic and environmental risk factors. A major risk factor for neurodegenerative disease is exposure to traumatic brain injury (TBI). Here, we investigated the synergistic interplay between TDP-43 dysfunction and TBI in a murine model of amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). A model of TDP-43 dysfunction caused by a knock-in Q331K mutation in Tardbp was combined with a mild model of TBI. Control conditions included both WT mice and mice with sham surgery. Animals were evaluated for behavioral deficits at timepoints pre- and post-surgery. Additionally, post-mortem brain tissues were examined using RNA sequencing and mass spectrometry-based quantitative proteomics together with histological and biochemical analyses. Expression of dysfunctional TDP-43 in vivo caused deficits in multiple branches of the proteostasis network, including protein folding, protein synthesis, and protein turnover. Examples include mis-expression of chaperones and genes within the ubiquitin-proteosome pathway in mutant TDP-43 versus WT mice. Further, mutant TDP-43 expression correlated with reduced thermostability of proteins associated with the ribosome and the chaperonin containing TCP-1 complex. In response to TBI, mutant TDP-43 mice exhibited significantly worse neurological outcomes relative to WT animals. Heightened neurological deficits in mutant TDP-43 mice following TBI coincided with a robust upregulation of proteostasis- and stress-related genes at the transcript level. However, this upregulation was not detected at the protein level. Our data demonstrate that expression of dysfunctional TDP-43 leads to deficits within the proteostasis network in vivo at baseline. Despite an upregulation of proteostasis-related genes at the transcript level in mutant TDP-43 mice after TBI, mutant TDP-43 mice exhibit an impaired response to, and recovery from, brain trauma relative to their WT counterparts. Restoring proteostasis is expected to protect against the detrimental effects of TDP-43 dysfunction, especially under stress conditions that promote neurodegenerative disease.

ID: 41303511
Title: TDP-43 Regulates Rab4 Levels to Support Synaptic Vesicle Recycling and Neuromuscular Connectivity in Drosophila and Human ALS Models.
Abstract: The pathological loss of nuclear TDP-43 is a hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), leading to extensive alterations in RNA metabolism and a broad number of neuronal transcripts. However, the key effectors linking TDP-43 dysfunction to synaptic defects remain unclear. In this study, using Drosophila and human iPSC-derived motoneurons, we identify Rab4 as a direct and conserved target of TDP-43, whose expression is necessary and sufficient to recover synaptic vesicle recycling, neuromuscular junction growth, and locomotor function in TDP-43-deficient motoneurons. Moreover, Rab4 activity promotes the presynaptic recruitment of futsch/MAP1B, a microtubule-associated protein also regulated by TDP-43, which autonomously supports synaptic growth and vesicle turnover. Together, these findings define a TDP-43/Rab4/futsch/MAP1B regulatory axis that couples endosomal dynamics to cytoskeletal assembly. Furthermore, this functionally coherent module provides a mechanistic basis for understanding how synaptic vulnerability is amplified in disease and offers a framework to identify key compensatory targets capable of sustaining neuronal function in the absence of TDP-43.

ID: 41490046
Title: TDP-43-mediated alternative polyadenylation is associated with a reduction in VPS35 and VPS29 expression in frontotemporal dementia.
Abstract: TAR DNA-binding protein 43 (TDP-43) dysfunction is a hallmark of several neurodegenerative diseases, including frontotemporal dementia, amyotrophic lateral sclerosis, and Alzheimer's disease. Although cryptic exon inclusion is a well-characterized consequence of TDP-43 loss of function, emerging evidence reveals broader roles in RNA metabolism, notably in the regulation of alternative polyadenylation (APA) of disease-relevant transcripts. In the present study, we examined 3' untranslated region lengthening events in the brains of individuals with frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP), focusing on the functional impact of APA dysregulation. To investigate whether TDP-43-mediated APA events occur in the postmortem brain, we measured the 3' untranslated region length of the retromer component vacuolar protein sorting 35 (VPS35) and the ETS transcription factor (ELK1) in the frontal cortex of a large cohort of FTLD-TDP patients and of healthy controls, and evaluated if these APA events are associated with FTLD-TDP clinical characteristic, markers of TDP-43 pathology [e.g., hyperphosphorylated TDP-43 and cryptic stathmin-2 RNA], or the expression of VPS35 and VPS29 proteins, the latter being essential to the retromer complex. We identified robust 3' untranslated region lengthening of VPS35 and ELK1 in FTLD-TDP, which strongly associated with markers of TDP-43 pathology, and ELK1 APA also associated with an earlier age of disease onset. Functionally, VPS35 APA was associated with reduced VPS35 and VPS29 protein expression, and lower VPS35 levels were associated with increased hyperphosphorylated TDP-43 and cryptic stathmin-2 RNA. Together, these data implicate APA dysregulation as a critical downstream consequence of TDP-43 dysfunction and suggest that TDP-43 loss may contribute to retromer impairment through APA-mediated repression of retromer subunits.

ID: 41498748
Title: Rsp5/NEDD4 and ESCRT regulate TDP-43 toxicity and turnover via an endolysosomal clearance mechanism.
Abstract: A pathological hallmark in >97% of amyotrophic lateral sclerosis (ALS) cases is the cytoplasmic mislocalization and aggregation of TDP-43, a nuclear RNA-binding protein, in motor neurons. Driving clearance of cytoplasmic TDP-43 reduces toxicity in ALS models, though how TDP-43 clearance is regulated remains controversial. We conducted an unbiased yeast screen using high-throughput dot blotting to identify genes that affect TDP-43 levels. We identified ESCRT complex genes, which induce membrane invagination (particularly at multivesicular bodies; MVBs) and genes linked to K63 ubiquitination (particularly cofactors of the E3 ubiquitin ligase Rsp5; NEDD4 in humans), as drivers of TDP-43 endolysosomal clearance. TDP-43 colocalized and bound Rsp5/NEDD4 and ESCRT proteins, and perturbations to either increased TDP-43 aggregation, stability, and toxicity. NEDD4 also ubiquitinates TDP-43. Lastly, TDP-43 accumulation induces giant MVB-like vesicles, within which TDP-43 accumulates in a NEDD4-dependent manner. Our studies shed light on endolysosomal-mediated cytoplasmic protein clearance, a poorly understood proteostasis mechanism, which may help identify novel ALS therapeutic strategies.

ID: 41546756
Title: Inhibiting Glycogen Synthase Kinase 3 Suppresses TDP-43-Mediated Neurotoxicity in a Caspase-Dependent Manner.
Abstract: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are progressive neurodegenerative diseases characterised by TAR DNA-binding protein 43 kDa (TDP-43) pathology. We previously showed that deletion of glycogen synthase kinase-3 (GSK3) suppresses TDP-43-mediated motor neuron degeneration in Drosophila. Here, we investigated the potential of GSK3 inhibition to ameliorate TDP-43-mediated toxicity in mammalian neurons. We show that TDP-43 activates GSK3 and promotes caspase-dependent cleavage of TDP-43, generating C-terminal fragments. We determine the functional importance of the N-terminal Asp89 caspase cleavage site in regulating TDP-43 proteostasis in both wild-type and ALS-linked TDP-43 variants and show that GSK3 inhibition selectively reduces truncated TDP-43 species, lowers nuclear TDP-43 levels, and improves neuronal survival. Neuroprotective effects were conserved in primary rodent cortical neurons, primary mouse motor neurons, and human iPSC-derived cortical neurons, highlighting the potentially broad therapeutic potential of GSK3 inhibition. We also find that the GSK3 inhibitor CHIR99021 reduces GSK3 RNA and protein expression and increases GSK3 phosphorylation, indicating novel mechanisms by which it acts to inhibit GSK3 activity. Unexpectedly, an N-terminally truncated variant (TDP-43N-Del), originally designed as a negative transfection control, exerted modest toxicity, potentially through retained susceptibility to caspase cleavage. Together, our findings uncover a caspase-mediated mechanism linking GSK3 activity to TDP-43 turnover, localisation, and neurotoxicity, and position GSK3 inhibition as a promising strategy to mitigate TDP-43-driven neurodegeneration in ALS-FTD.

ID: 41571890
Title: Rgnef regulates bone mass through the activation of RhoA and Rac1.
Abstract: Rho guanine nucleotide exchange factor (Rgnef/p190RhoGEF), a RhoA-specific guanine nucleotide exchange factor, has been implicated in cancer and amyotrophic lateral sclerosis, but little is known about its role in bone. Here we investigate the roles of Rgnef in bone metabolism using Rgnef-deficient and overexpressing mice. Compared with littermate wildtype mice, Rgnef-deficient mice had increased bone mass owing to lower osteolysis and higher osteogenesis, and Rgnef-overexpressing transgenic mice had the opposite bone phenotype. Rgnef deficiency inhibited osteoclast formation and resorptive function and promoted osteoblast differentiation and mineralization, whereas Rgnef overexpression had the reverse effect. Mechanistically, Rgnef promotes osteoclastogenesis by enhancing the activity of nuclear factor kappa B (NF-κB), mitogen-activated protein kinases and AKT through the activation of RhoA and Rac1 and attenuates osteoblastogenesis through the RhoA/Rac1-mediated NF-κB activation. Moreover, Rgnef-deficient mice were protected from bone loss caused by lipopolysaccharide-induced inflammation or ovariectomy. Thus, Rgnef is a crucial regulator of bone metabolism and could serve as a potential new target for treating bone diseases.

ID: 41576445
Title: Noise exposure induces autophagy-modulated nuclear-to-cytoplasmic translocation of TDP-43 in spiral ganglion neurons.
Abstract: Noise exposure contributes to approximately one-third of hearing loss cases worldwide. Despite its substantial global burden, noise-induced hearing loss (NIHL) remains essentially irreversible, largely because its underlying pathogenic mechanisms are not yet fully defined. In this study, we established three noise-induced hearing loss mouse models and evaluated auditory function by measuring auditory brainstem response (ABR) thresholds at multiple time points following noise exposure. In parallel, we examined the spatiotemporal redistribution of TDP-43 and evaluated autophagic flux in spiral ganglion neurons (SGNs) to elucidate their dynamic responses to acoustic stress. Noise exposure triggers marked nucleocytoplasmic translocation and cytoplasmic aggregation of TDP-43 in spiral ganglion neurons (SGNs), accompanied by dynamic alterations in autophagic flux. Using pharmacological modulation, we demonstrate that autophagy critically shapes the fate of TDP-43. Mechanistically, noise-induced stressors such as reactive oxygen species (ROS) likely initiate TDP-43 nuclear export, whereas insufficient autophagic flux impedes aggregate degradation and exacerbates cytoplasmic inclusion formation. Together, these findings reveal autophagy as a key determinant of TDP-43 dynamics in the auditory system and identify the autophagy-TDP-43 axis as a potential therapeutic target for preventing or ameliorating noise-induced hearing loss.

ID: 41614607
Title: Concentration-dependent cytoplasmic phase separation of TDP-43 drives aggregation and proteinopathy.
Abstract: TDP-43 mislocalization and aggregation are common features of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). However, the mechanisms underlying the transition of nuclear TDP-43 to cytoplasmic aggregates, and their contribution to disease pathogenesis, remain poorly understood. To address this gap, we present a methodology to chemically control the assembly and disassembly of cytoplasmic TDP-43 condensates. By fusing TDP-43 to a phase separation-prone protein scaffold, we can induce the formation of cytoplasmic TDP-43 condensates or, conversely, promote nuclear localization upon addition of a disassembly molecule. TDP-43 accumulates into various assemblies, ranging from submicrometric puncta to larger aggregate-like structures that display hallmarks of proteinopathy in a concentration-dependent manner. Furthermore, oxidative stress drives the maturation of TDP-43 assemblies from puncta into aggregates through interactions with stress granule components. Finally, we show that cytoplasmic TDP-43 aggregates deplete nuclear endogenous TDP-43 and induce cytotoxicity. Collectively, these findings highlight the local cytoplasmic concentration of TDP-43 and stress exposure as key determinants in the onset of TDP-43 proteinopathy, providing a relevant model to study pathological TDP-43 aggregation.

ID: 41634873
Title: Chaperone mediated autophagy is deficient in spinal motoneurons of ALS patients with TDP-43 proteinopathy.
Abstract: Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease characterized by the selective loss of motor neurons (MNs), ultimately resulting in paralysis and respiratory failure within 3 to 5 years of onset. Fewer than 10% of ALS cases are familial (fALS), while the vast majority are sporadic (sALS) with an unknown etiology. A pathological hallmark of ALS is the accumulation of misfolded TDP-43 protein aggregates within MNs. Although TDP-43 is known to be degraded via chaperone-mediated autophagy (CMA), the status of CMA activity in sALS has not been previously explored. To investigate this, we analyzed CMA in human spinal cord tissue by assessing the expression of LAMP2A, a key lysosomal receptor and marker of CMA activity. In control samples, spinal cord MNs exhibited robust LAMP2A expression. In contrast, MNs from sALS patients showed a marked reduction in LAMP2A levels, coinciding with the presence of TDP-43 pathology. Notably, analysis of LC3, a marker of macroautophagy, revealed no significant differences in expression between control and sALS MNs. Interestingly, MNs within the Onuf’s nucleus, a population known to be resistant to degeneration in ALS, retained normal LAMP2A expression and did not exhibit TDP-43 aggregation in sALS cases. These findings demonstrated that CMA is essential for the clearance of TDP-43 in spinal cord MNs and that its dysfunction may contribute to the pathogenesis of sALS. Furthermore, the high dependence of spinal cord MNs on CMA activity may underlie their selective vulnerability to degeneration when CMA is impaired, and highlight CMA enhancement as a promising therapeutic strategy to restore proteostasis and prevent MN degeneration in ALS.

ID: 41637622
Title: Aberrant Splicing Signatures Underpin Oligodendrocyte Damage in ALS and Neuron Loss in FTD.
Abstract: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two severe diseases sharing similar genetic, pathological, and clinical features, including TDP-43 pathology. However, differences in molecular changes between ALS and FTD remain elusive. Here, integrating large sets of bulk and single-nucleus RNA-seq from ALS/FTD patients revealed expression and splicing changes indicating more severe oligodendrocyte damage in ALS than FTD, and more significant neuron loss in FTD. Specifically, we identified 31 oligodendrocyte-specific and 507 neuron-specific aberrant splicing junctions as potential biomarkers with robust classification performance, and experimentally validated a novel target in patient tissues. Moreover, we found that abnormally spliced transcripts produced de novo peptides in patients' cerebrospinal fluids. Importantly, we further identified the targets of TDP-43 in glial cells and decoded the differential RNA-binding protein (RBP) contexts of TDP-43-regulated aberrant splicing. These findings uncover that ALS and FTD patients have distinct dysfunctional cell populations harboring specific aberrant splicing signatures, suggesting varying cellular impacts and providing potential biomarkers and insights into molecular mechanisms underlying ALS/FTD.

ID: 41720774
Title: A neurotoxic cryptic peptide arising from TDP-43-dependent cryptic splicing of PKN1.
Abstract: Dysfunction of transactive response DNA-binding protein 43 (TDP-43) drives neurodegeneration in amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD), in part through inducing aberrant RNA splicing. However, whether such mis-splicing yields stable, pathogenic proteins remains unclear. Here, we identify a TDP-43-repressed cryptic exon in Protein kinase N1 (PKN1), designated PKN1-5a1, which is activated in ALS patient brains and introduces a premature termination codon. This aberrant transcript escapes nonsense-mediated decay and is translated into a truncated peptide, PKN1-N207 (PKN207), detectable in AD brains with TDP-43 pathology. In mice, PKN207 impairs cognition, memory, and synaptic plasticity. Our findings demonstrate that TDP-43 loss-induced cryptic splicing can generate stable neurotoxic polypeptides, revealing a peptide-mediated mechanism in TDP-43 proteinopathies.

ID: 41809005
Title: cGAS inhibition delays TDP-43-driven ALS Pathogenesis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder marked by motor neuron loss and cytoplasmic mislocalization of TAR DNA-binding protein 43 (TDP-43), a key regulator of RNA splicing. However, the upstream modulators of this process remain poorly defined. Here we identify cyclic GMP-AMP synthase (cGAS) as a central mediator of TDP-43 pathology and associated mis-splicing. cGAS expression was elevated in ALS patient brains and enriched across activated microglia. In human iPSC-derived microglia-motor neuron co-cultures, neuronal TDP-43 pathology triggered microglial cGAS activation, whereas pharmacological inhibition with a potent human cGAS inhibitor reduced phosphorylated TDP-43, restored lysosomal and phagocytic programs, normalized microglial reactivity, and reversed TDP-43-associated RNA splicing defects. In vivo, cGAS inhibition in TDP-43 Q331K mice reversed widespread RNA splicing abnormalities across neurons and oligodendrocyte lineage cells, attenuated neurodegenerative pathology, and preserved motor function. Together, these findings identify cGAS as a druggable upstream regulator linking innate immune signaling to TDP-43-dependent RNA mis-splicing and neurodegeneration, and establish cGAS inhibition as a promising therapeutic strategy for ALS.

ID: 41845971
Title: The role of TDP-43 fragments in regular cellular functions and homeostatic failure.
Abstract: Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of motor neurons, leading to severe muscle weakness, loss of voluntary movement, and respiratory failure. A widely noted feature of the disease is the presence of TDP-43 proteinopathies. Under homeostatic conditions, the RNA/DNA-binding protein TDP-43 mainly resides in the nucleus, where it functions to regulate gene expression, controlling not only RNA transcription and splicing, but also stability and transport to the cytoplasm. Upon the arrival at ribosomes, TDP-43 may further moderate translation, acting as a global repressor of protein synthesis. However, in over 95% of ALS cases, TDP-43 mislocalises from the nucleus to the cytoplasm, where it enriches in cytoplasmic inclusions that are marked by the presence of misfolded, ubiquitinated, phosphorylated and fragmented protein species of TDP-43. Although recent studies have tried to untangle the relationship between TDP fragments on the one hand, and cytotoxicity as well as neurodegeneration on the other, the results are still a matter of debate. Here, we review our current understanding of the different TDP fragments derived from proteolytic cleavage as well as alternative splicing, addressing the different N-terminal and C-terminal species and evaluating differences in rodent and primate models. We focus our analysis on potential homeostatic functions of TDP fragments in the context of viral infections and myelination control, which could be pivotally interconnected. The findings illustrate several facets of fragmented TDP-43 protein species in scenarios of enhanced cellular stress. Gaining a detailed understanding could help to reveal new treatment options for ALS and other TDP-43 proteinopathies.

ID: 41888437
Title: Preservation of miR-9-5p and miR-124-3p in ALS-resistant oculomotor neurons contrasts with their downregulation in vulnerable spinal motor neurons, irrespective of TDP-43 pathology.
Abstract: Selective vulnerability of motor neurons is a defining feature of amyotrophic lateral sclerosis (ALS) and provides a valuable framework for uncovering mechanisms that distinguish resilient from vulnerable neuronal populations. We investigated whether dysregulation of neuroprotective microRNAs (miRNAs), miR-9-5p and miR-124-3p, contributes to the differential susceptibility of motor neuron subtypes. We focused on cervical spinal motor neurons (SMNs), which undergo drastic degeneration in ALS, and oculomotor neurons (OMNs), which remain functionally intact and rarely degenerate, allowing preservation of eye movement in ALS patients. Using a modified multiplexed fluorescent in situ hybridization protocol combined with immunofluorescence, we quantified the expression of miR-9-5p and miR-124-3p in cervical SMNs and OMNs from ALS and control cases. We observed significant downregulation of both miRNAs in ALS SMNs, while their expression was maintained in ALS OMNs. Stratification of ALS SMNs by TDP-43 pathological status revealed similarly reduced miRNA expression in neurons with and without cytoplasmic inclusions, suggesting that miRNA downregulation occurs independently of visible TDP-43 pathology. We assessed the localization of the Dicer cofactor TRBP and found that it colocalized with TDP-43 inclusions in ALS SMNs, suggesting that TRBP sequestration could prevent proper miRNA processing. However, TRBP remained normally localized in neurons without cytoplasmic inclusions, indicating that sequestration cannot fully account for miRNA reduction across all ALS motor neurons. These findings support a model in which early or subtle disruptions, preceding visible pathology, may also contribute to miRNA downregulation in ALS. By identifying preserved miRNA networks as correlates of oculomotor neuron resilience in ALS, this work also exposes new therapeutic targets potentially capable of reinstating miRNA expression and reprogramming vulnerable SMNs.

ID: 41926608
Title: Relationship between promyelocytic leukemia protein nuclear bodies and TAR DNA-binding protein-43 aggregation in spinal anterior horn cells in sporadic amyotrophic lateral sclerosis.
Abstract: Promyelocytic leukemia protein nuclear bodies (PML-NBs) and stress granules serve as deposition sites for stress-induced, aggregation-prone proteins. We previously reported that TAR DNA-binding protein 43 (TDP-43) colocalizes with stress granules during early aggregation in sporadic amyotrophic lateral sclerosis (ALS), and recent studies have noted PML-NB loss in familial ALS. To explore the role of PML-NBs in TDP-43 inclusion maturation, we analyzed spinal cord specimens from 12 patients with sporadic ALS and 5 controls using immunostaining for PML and TDP-43. PML-NB counts in anterior horn cells (AHCs) were significantly lower in patients with ALS than in controls (P < 0.05), especially in AHCs with TDP-43 inclusions (P < 0.01). Average numbers of PML-NB decreased progressively with inclusion type (3.1 in diffuse punctate cytoplasmic staining, 2.3 in round inclusions, and 0.8 in skein-like inclusions); all of these were significantly lower than those in inclusion-free AHCs (controls: 4.6; ALS: 5.5; P < 0.01). AHCs in ALS without inclusions showed higher PML-NB counts than in controls (P < 0.05), suggesting an early protective response. In contrast, reduced PML-NBs in mature inclusions may reflect diminished cellular defense. These findings implicate PML-NBs in the pathogenesis of sporadic ALS.

ID: 41940964
Title: Genetic and environmental risk factors of Parkinsonism.
Abstract: Parkinsonian disorders comprise a broad spectrum of neurodegenerative diseases with a wide variety of pathogenetic processes. These processes lead to the formation of pathological proteins, resulting in the brain diseases called synucleinopathies, tauopathies or TDP-43 proteinopathies. There is currently growing support for the hypothesis that genetic variants explain a significant fraction of the etiology of apparently sporadic parkinsonian disorders. Genetic risk factors can be stratified according to the metabolic or structural processes that can lead to cellular disturbance; these processes involve protein aggregation, protein and membrane trafficking, stabilization of the neurite structure, prion-like transmission of pathological proteins, ubiquitin-proteasome system balance, mitophagy, lysosome autophagy, synaptic functions, and dopamine transmission. Regarding the environmental risk factors, there are several substances that have been supposed of being a risk for the development of neurodegenerative proteinopathy and Parkinsonism, mainly the agents used in agriculture and the textile industry. The most important and most frequently studied are pesticides and trichlorethylene. Beside the globally ubiquitous substances which are supposedly neurotoxic and exposure to which can cause manifestations of Parkinsonism, there are more geographically (regionally) specific substances, which cause (or quite recently caused) the manifestation of endemically present Parkinsonism. Among ten types of endemic Parkinsonism, three of them are thought to have an environmental cause: Western Pacific Parkinsonism, Caribbean Parkinsonism, and North France cluster of atypical Parkinsonism.

ID: 42024684
Title: Effects of concurrent neuropathologies with Alzheimer disease neuropathologic change on cognitive decline: Minimal impact of vascular brain injury compared with other combinations.
Abstract: We examined cognitive changes associated with several neuropathologic entities, alone and in combination. We studied 808 participants from the National Alzheimer's Coordinating Center to assess associations between neuropathologic diagnoses (from autopsy) and neuropsychologic test scores (trajectories over time for 5 domains: overall cognition, episodic memory, attention, language, executive function). Neuropathologies included: Alzheimer disease neuropathologic change (ADNC), Lewy body disease (LBD), vascular brain injury (VBI), and limbic-predominant age-related TDP43 encephalopathy neuropathologic change (LATE-NC). Using linear mixed-effects models, we examined trajectories of cognitive decline for ADNC alone compared to ADNC plus LBD, VBI, or LATE-NC. We also examined differences between observed trajectories and trajectories that would be expected if the neuropathologic entities exerted their effects independently (additively). ADNC+LBD had worse decline than ADNC alone for 4 of the 5 domains with rate of decline consistent with an additive model for all 4 domains. ADNC+LATE-NC had worse decline than ADNC alone for 3 domains with rate of decline additive for only one and <additive for 2. ADNC+VBI had worse decline than ADNC alone for only one domain, with rate of decline <additive. These findings are relevant for prognostication in clinical practice and for clinical trial design.

ID: 42029805
Title: TDP-43 Dysfunction Causes Hyper-Lactate State, Increased AARS1 Expression and Enhanced Protein Lactylation.
Abstract: Objective abnormal function of TAR DNA-binding protein of 43 (TDP-43) is closely associated with the development of various neurodegenerative diseases. Previous studies have shown that TDP-43 dysfunction induces mitochondrial damage. However, whether TDP-43 dysfunction further promotes lactate accumulation and enhances protein lactylation remains unclear. This study aimed to investigate the effects of TDP-43 loss-of-function on lactate metabolism and protein lactylation. Methods a neuron-specific TDP-43 conditional knockout mouse model (TDP-43 cKO mice) and a TDP-43 knockdown NSC34 cell model were established. Survival was recorded and motor function was monitored in TDP-43 cKO mice. Mitochondrial morphology and mitochondrial DNA (mtDNA) leakage were examined by high-speed structured illumination microscopy (HIS-SIM). L-lactate levels were quantified using an L-lactate detection kit. TDP-43 and AARS1 mRNA levels were measured by RT-qPCR. The degree of protein pan-lactylation and the expression of TDP-43 and AARS1 were analyzed by Western blot. Results TDP-43 cKO mice exhibited motor deficits and shortened lifespan. In the TDP-43 knockdown cell model, TDP-43 deficiency caused marked mitochondrial structural and functional abnormalities, including reduced mitochondrial number and perimeter, mtDNA leakage, decreased mitochondrial membrane potential, reduced ATP production and impaired cell viability. In both the motor cortex of TDP-43 cKO mice and cell model, L-lactate levels, pan-lactylation, and AARS1 expression were significantly increased. In addition, sodium lactate treatment further enhanced pan-lactylation and AARS1 protein expression in NSC34 cells. Conclusion TDP-43 deficiency induces mitochondrial injury and is associated with lactate accumulation, increased protein lactylation, and AARS1 upregulation. These findings provide new insights into the mechanisms underlying TDP-43 loss-of-function-mediated neurodegeneration and suggest potential therapeutic targets for TDP-43-related neurodegenerative diseases.

ID: 42051315
Title: Statins and genetic inhibition of the mevalonate pathway activate an ATF3-STMN2 regenerative program.
Abstract: Loss of neuronal regenerative capacity is a common feature of neurodegenerative disease and axonal injury, yet the transcriptional programs governing this state remain poorly defined. Stathmin-2 (STMN2), a tubulin-binding protein essential for axon maintenance and repair, is profoundly depleted following loss of nuclear TDP-43 in neurodegenerative disease. Here, we identify statins as potent inducers of STMN2 expression. Pharmacological and genetic suppression of the mevalonate pathway, and subsequent prevention of protein geranylgeranylation, restored STMN2 levels in TDP-43 deficient cells and promoted neurite growth. STMN2 induction was abrogated when using a statin analogue unable to interact with HMG-CoA reductase, and through co-administration of mevalonate or geranylgeranyl diphosphate substrates. RNA-seq revealed that statins induce a coordinated pro-regenerative transcriptional response, including activation of the AP-1 transcription factor complex gene, ATF3. Loss of ATF3 attenuated STMN2 induction in vitro, and diminished injury-induced Stmn2 upregulation in spinal motor neurons in vivo. These results demonstrate statins as modulators of ATF3 and STMN2 expression and highlight their therapeutic potential in neurodegenerative disease.

ID: 42063624
Title: Amyloid beta pathology induces astrocytic pTDP-43 mislocalization and disrupts TDP-43-regulated cryptic exon transcripts.
Abstract: While amyloid-β (Aβ) and tau are hallmark pathologies of Alzheimer's disease (AD), TDP-43 proteinopathy is increasingly recognized as an important contributor, occurring in up to 57% of AD cases and associated with accelerated cognitive decline. TDP-43 regulates RNA splicing, and its mislocalization leads to cryptic exon inclusion and loss of canonical protein function. While neuronal TDP-43 pathology has been well studied, its role in astrocytes remains less understood. Recent findings suggest increased phosphorylated TDP-43 (pTDP-43) inclusions in astrocytic endfeet in AD and a bidirectional interaction between Aβ and TDP-43, promoting mutual aggregation. We analyzed pTDP-43 immunoreactivity (IR) in astrocytic perivascular end-feet, nuclei, and cytosol in hippocampal sections from 3-month-old and 18-month-old AppNL-F/NL-F mice and 18-month-old wild-type controls using ImageJ. In vitro, primary fetal human astrocytes were exposed to oligomeric Aβ42, and changes in cytosolic and nuclear pTDP-43 IR were quantified via ImageJ, while TDP-43 and pTDP-43 protein levels were measured using an in-house ELISA. Expression of canonical transcripts ATG4B and KALRN, involved in autophagy and synaptic support, was assessed by qPCR. Corresponding protein-level changes were evaluated using in-house ELISA. Our findings demonstrate significantly higher pTDP-43 accumulations in astrocytic nuclei, cytosol, and endfeet in 18-month-old AppNL-F/NL-F mice compared to age-matched wild-type mice. Astrocytes exposed to oligomeric Aβ42 showed elevated cytosolic pTDP-43 IR and total pTDP-43 protein levels. Concurrently, expression of canonical ATG4B and KALRN transcripts was significantly reduced, which was accompanied by corresponding decreases in protein levels. Our findings demonstrate that pTDP-43 accumulates in astrocytic nuclei, cytosol, and endfeet in the presence of AD pathology. The observed Aβ-induced increase in cytosolic pTDP-43 and transcript disruption suggests a mechanistic link contributing to autophagy impairment and cytoskeletal changes in astrocytes, potentially exacerbating AD progression.

ID: 42129145
Title: A human Staufen1 BAC transgenic mouse exhibits abnormal autophagy and neurodegeneration across the central nervous system.
Abstract: RNA-binding proteins (RBPs) play an essential role in development, normal functioning, and human disease. Staufen1 (STAU1) is an RBP that regulates mRNA degradation and subcellular localization, and is part of the ATXN2 protein complex. Previously, we showed that STAU1 is overabundant in patient fibroblasts and in mouse models of Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and spinocerebellar ataxia type 2 (SCA2), where it is associated with impaired autophagic flux due to STAU1-mediated upregulation of mTOR translation. STAU1 overabundance and impaired autophagy cause accumulation of biomolecular condensates and abnormal unfolded protein response (UPR). We generated a mouse model expressing the entire human STAU1 gene (hSTAU1) in a bacterial artificial chromosome (BAC) construct. hSTAU1 in these mice was expressed in cerebral hemispheres, cerebellum, and spinal cord, as well as cultured cortical neurons and cortical and spinal cord astrocytes, and microglia. Expression of hSTAU1 caused dysregulated gene expression, abnormal autophagy, glial activation, and changes in neuronal marker proteins. All of these were significantly improved by reducing STAU1 abundance by RNAi, but exacerbated in BAC-STAU1 mice crossed with Prp-TDP-43(Q331K) transgenic mice. Similar results were also obtained in eye phenotypes in ALS- and SCA2-relevant fly models upon changing staufen-1 dosage. Despite the molecular changes, we observed no overt behavioral changes in mice up to 55 weeks of age, suggesting that STAU1 may function as an epistatic modifier of neuronal degeneration. The BAC-hSTAU1 mouse will be useful for developing therapies targeting the human STAU1 gene.

ID: 42135750
Title: Maintenance and disruption of the physiological dimer structure of TDP-43 in amyotrophic lateral sclerosis and frontotemporal lobar degeneration.
Abstract: Transactive response DNA-binding protein of 43 kDa (TDP-43) is an essential regulator of RNA metabolism, playing a pivotal role in splicing, transport, and stability. While its cytoplasmic aggregation is the pathological hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), recent evidence suggests that the earliest pathogenic event is the disruption of its physiological homodimeric structure. Under healthy conditions, TDP-43 forms dimers via its N-terminal domain, a configuration that is crucial for its nuclear solubility and cooperative RNA binding. In this review, we propose the "Molecular Zipper" hypothesis to describe the maintenance of TDP-43 structural homeostasis. In this framework, the N-terminal domain acts as a stabilizing "NTD-mediated anchor" that keeps the protein in a functional, "zipped" dimeric state, effectively sequestering its aggregation-prone C-terminal regions. Pathogenic triggers-including genetic mutations, aberrant post-translational modifications such as phosphorylation and acetylation, and environmental stressors-can "unzip" this structure, leading to the formation of pathogenic monomers. These pathogenic monomers show increased propensity for cytoplasmic mislocalization and recruit wild-type protein into aggregates through a prion-like seeded aggregation mechanism, culminating in nuclear functional loss and cytoplasmic gain-of-toxicity. We further evaluate the emerging diagnostic landscape, focusing on methods to monitor the dimer-to-monomer ratio. Integrating prior biochemical data on TDP-43 dimerization with structural modeling enables a more coherent account of the transition from the physiological dimer to pathological conformers. The Molecular Zipper framework offers a conceptual foundation for reconciling existing experimental findings and for guiding future studies on early structural changes in TDP-43 proteinopathy.

ID: 42165374
Title: Lighting Up Mislocalized Proteins: Quantum Dot Probes for Multiplexed Cytoplasm-Selective Cell Profiling in Neurodegeneration.
Abstract: Semiconductor quantum dots (QDs) provide unique stability, brightness, and multiplexed capacity for biomarker detection in complex diseases; however, their distinctive intracellular distribution has rarely been leveraged for spatially resolved diagnostics. Here, we show how QD-based sensors enable selective detection of cytoplasmic proteins and can quantify nucleo-cytoplasm protein mislocalization in patient-derived samples. We validated this approach labeling TAR DNA-binding protein 43 (TDP-43), a key mislocalized protein in amyotrophic lateral sclerosis (ALS). Spatial resolution is achieved in several patient-derived models and mouse brain tissue, underscoring the nanosensor's versatility across biological systems. Multiplexed QD-based immunolabeling, combined with confocal imaging and high-throughput flow cytometry, enables the detection of distinct cytoplasmic biomarker signatures that discriminate ALS patients from healthy controls. These signatures include variations in TDP-43 mislocalization and protein coexpression patterns, which were further modulated by pharmacological treatment. This work establishes QDs as spatially selective, multiplexable nanosensors capable of resolving subtle yet disease-relevant intracellular phenotypes in patient-derived samples. Compared to organic fluorophores, QDs enhance sensitivity, improve signal stability, and enable simultaneous spatially resolved biomarker quantification, broadening their potential for clinical diagnostics and personalized medicine. These findings establish QDs as powerful tools for neurodegeneration research, disease monitoring, and early biomarker discovery, with potential applications in translational neuroscience and precision medicine.

ID: 42167675
Title: TDP-43: a critical amplifier of Alzheimer's disease beyond amyloid and tau.
Abstract: TAR DNA-binding protein 43 (TDP-43) proteinopathy has recently emerged as a pivotal, yet underrecognized, contributor to the multifaceted neuropathology of Alzheimer's disease (AD). While amyloid-β and tau have long been established as cardinal pathological hallmarks, growing evidence delineates TDP-43 as a critical participant of neurodegeneration, intricately interwoven with amyloid and tau pathologies. TDP-43 mislocalization, post-translational modifications, and aggregation potentiate neuronal loss through disruption of RNA metabolism, nucleocytoplasmic transport, and protein homeostasis. This tripartite interplay manifests in synergistic and possibly multidirectional pathological cascades that amplify neuronal vulnerability and cognitive decline, thereby complicating the clinical and pathological complexity of AD. Here, we critically reviewed the mechanistic crosstalk among TDP-43, amyloid-β, and tau, focusing on preclinical and clinical evidence, highlighting possible convergent pathways of aggregation, propagation, and neurodegeneration. Moreover, this review also evaluates mitochondrial dysfunction, autophagy failure, and inflammation as underlying events associated with TDP-43 pathology. Therefore, we argue for a reconceptualization of AD as a dynamic proteinopathy network, with TDP-43 as a core integrative node influencing disease onset and its progression. Notably, we discuss emerging diagnostic modalities associated with molecular tracers of TDP-43, providing prospects for future biomarker identification. Finally, this review articulates the translational relevance of TDP-43 therapy in AD and related neurological disorders, emphasizing the necessity of holistic approaches that transcend the traditional amyloid-tau paradigm to effectively tackle the full spectrum of AD pathobiology.

ID: 42171508
Title: Kinetics and Spatial Distribution of β-Sheet Development in TDP-43CTD Condensate Maturation.
Abstract: Cytosolic inclusions of aggregated TAR DNA-binding protein 43 (TDP-43) are hallmarks of neurodegenerative disorders such as amyotrophic lateral sclerosis and frontotemporal lobar dementia. A prevailing hypothesis suggests that TDP-43 condensates undergo a liquid-to-solid transition during maturation, involving the formation of β-sheet-rich, amyloid-like aggregates. To test this hypothesis, we sought to study the temporal and spatial evolution of protein secondary structure within individual condensates by Raman spectroscopy. We measured in vitro β-sheet development of the C-terminal domain of TDP-43 (TDP-43CTD) at the single-condensate level under physiological solution conditions. All condensates showed apparent single-exponential kinetics (k = 1.6 × 10-5 s-1) for the disordered-to-β-sheet transformation, as indicated by increased amide-I intensity and a shift of the amide-III band to lower energy. Interestingly, the water bend-libration band exhibited a slower rate (k = 4.0 × 10-6 s-1), suggesting that changes in the water environment lag behind protein conformational rearrangement. Further, Raman maps revealed that protein density is highest near the condensate center, whereas β-sheet content is mostly uniform in the interior of the condensate. The unexpected difference between the spatial distributions of β-sheet content and protein density challenges the typical concentration-dependent model of protein aggregation. Importantly, rare events were captured where condensates exhibited spatially asymmetric β-sheet development, revealing localized structural heterogeneity not detectable by ensemble measurements. Collectively, these results provide insight into the temporal and spatial dynamics of protein structure within TDP-43CTD condensates and demonstrate the utility of Raman spectral imaging for tracking condensate maturation.

ID: 42178739
Title: Proteomic Analysis of Corpora Amylacea Extracted From Post-mortem Brain of MAiD-end-of-life Sporadic ALS Patients.
Abstract: Corpora amylacea (CA) are starch-like inclusions that accumulate in the central nervous system (CNS) with aging and are enriched in neurodegenerative conditions, including amyotrophic lateral sclerosis (ALS). Although often regarded as waste reservoirs, their cellular origins, molecular composition, and pathological significance remain poorly understood. Here, we performed an unbiased proteomic analysis of purified CAs isolated from post-mortem brains of sporadic ALS patients and controls. In-depth mass spectrometry identified 4,470 proteins, of which 658 were quantified, revealing distinct ALS-specific proteomic signatures. Enriched proteins included markers of cytoskeletal remodeling, mitochondrial dysfunction, and proteostasis disruption, as well as known ALS-associated proteins such as TDP-43 and neurofilament proteins. These findings demonstrate that CAs serve as reservoirs of dysfunctional, disease-relevant proteins and capture key pathological processes in ALS. By applying an unbiased proteomic approach to purified CAs, this study provides the first comprehensive map of their protein content in ALS, supporting their potential as biomarker sources and as a source of mechanistic insights into neurodegeneration. Unbiased analyses of CAs in the context of ALS have yet to be undertaken. This study provides the first proteomic profiling of purified CAs, isolated from ALS patient brains using biochemical methods, revealing that CAs harbor disease-relevant proteins implicated in sporadic ALS. By demonstrating that CAs act as reservoirs of dysfunctional proteins related to metabolism, cytoskeletal organization, and proteostasis, our findings highlight their potential as a novel source of ALS-specific mechanistic insight into disease pathology.

ID: 42183628
Title: CHCHD2 and CHCHD10 promoted autophagic clearance of protein aggregates via GABARAPs.
Abstract: Mutations in mitochondrial protein CHCHD2 and its paralog CHCHD10 were identified in patients with Parkinson disease (PD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) or Alzheimer disease (AD). CHCHD2 and CHCHD10 mutations caused neurodegeneration in model animals as seen in patients, but their pathophysiological roles remain elusive. Here we reported a direct role of CHCHD2 and CHCHD10 in autophagy. We identified a protein complex composing of CHCHD2-CHCHD10-C1QBP/p32-Atg8-family proteins (ATG8s), in which each molecule interacted with another. CHCHD2, CHCHD10 and C1QBP/p32 associated with ATG8s, preferentially, GABARAPs. Disease-associated CHCHD2 and CHCHD10 mutations exhibited varied interaction with ATG8s. By binding to GABARAPs, CHCHD2 and CHCHD10 underwent autophagic degradation, and recruited the ULK1 complex. Autophagy initiation defects occurred upon transient knockdown of CHCHD2, and also in human iPSC-derived CHCHD2-/- or CHCHD2T61I dopaminergic neurons. Importantly, CHCHD2 and CHCHD10 promoted autophagy. CHCHD2 reduced protein aggregates in cells and toxic SNCA/α-synuclein species in mouse striatum. Our study thus revealed mitochondrial proteins CHCHD2 and CHCHD10 as both autophagy substrates and autophagy activators and laid groundwork for therapy targeting patients with neurodegeneration.Abbreviations: AA: amino acid; AD: Alzheimer disease; ALS: amyotrophic lateral sclerosis; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG8: mammalian Atg8-family protein; ATG13: autophagy related 13; bafA1: bafilomycin A1; C1QBP/p32/gC1qR/HABP1: complement component 1, q subcomponent binding protein; CHCHD2/MNRR1/MIX17B: coiled-coil-helix-coiled-coil-helix domain containing 2; CHCHD10/MIX17A: coiled-coil-helix-coiled-coil-helix domain containing 10; CHX: cycloheximide; CMA: chaperone-mediated autophagy; CRISPR: clustered regularly interspaced short palindromic repeats; CQ, chloroquine; DA: dopaminergic; DMSO: dimethyl sulfoxide; EBSS: Earle's balanced salt solution; RB1CC1/FIP200: RB1 inducible coiled-coil 1; FTD: frontotemporal dementia; GABARAP: gamma-aminobutyric acid receptorbassociated protein; GABARAPL1: GABA type A receptor associated protein like 1; GABARAPL2: GABA type A receptor associated protein like 2; hESC: human embryonic stem cells; iPSC: induced pluripotent stem cell; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; LAMP2A: lysosomal-associated membrane protein 2A; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; LIR: LC3-interacting region; PD: Parkinson disease; SQSTM1/p62: sequestosome 1; TARDBP/TDP-43: TAR DNA binding protein; TH: tyrosine hydroxylase; TMR, tetramethylrhodamine; WT: wild type; UB: ubiquitin; ULK1: unc-51 like kinase 1.

ID: 42204151
Title: Caspase-4 transgenic mice exhibit cytoplasmic TDP-43 accumulation and age-dependent neuropathology.
Abstract: TAR DNA-binding protein (TDP-43) is a multifunctional protein that binds DNA and RNA within the nucleus. In neurodegenerative diseases like Amyotrophic Lateral Sclerosis (ALS), TDP-43 is mislocalized to the cytoplasm, forming inclusions. Current TDP-43 transgenic mouse models generally fail to exhibit significant cytoplasmic accumulation and loss of nuclear TDP-43, which hampers the investigation of cytoplasmic TDP-43 pathology. We previously discovered that primate-specific caspase-4 (CASP4) can cleave TDP-43, producing truncated fragments that are mislocalized to the cytoplasm. Here we show that a transgenic mouse model that expresses human CASP4 and recapitulates the cytoplasmic mislocalization of endogenous TDP-43 and motor dysfunction in an age-dependent manner. Moreover, CASP4 mice exhibited gene expression changes and neuropathology similar to patients with sporadic ALS. Inhibition of CASP4 by its antisense oligonucleotide ameliorated TDP-43 pathology and subsequent neurotoxicity in CASP4 mice. Thus, CASP4 mice present a valuable animal model for exploring endogenous TDP-43-mediated pathogenesis and therapeutics.

ID: 42217760
Title: Fluid-based biomarkers of amyotrophic lateral sclerosis: recent advances and future prospects.
Abstract: Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder with no definitive cure. The absence of specific diagnostic biomarkers leads to diagnostic delays, hindering early intervention and management. This review provides a critical appraisal of fluid-based biomarkers for ALS across multiple sources-cerebrospinal fluid (CSF), blood, urine, saliva, and tears-with emphasis on their diagnostic and prognostic potential, limitations, and readiness for clinical translation. While neurofilaments (NfL, pNfH) are well-established as sensitive indicators of neuroaxonal injury and are increasingly used as prognostic and pharmacodynamic markers in clinical trials, they lack disease specificity. Biomarkers reflecting ALS-specific pathology, such as TDP-43 species and C9orf72 dipeptide repeat proteins (DPRs), show promise but remain in early validation stages with limited multicenter data. Emerging markers from non-invasive sources (urine p75ECD, salivary chromogranin A, tear metabolomics) offer potential for repeated sampling but require rigorous external validation before clinical adoption. To address current gaps, we introduce a standardized evidence grading framework (Tier 1-3) and a comprehensive reporting template for biomarker studies, including explicit performance metrics (AUC, sensitivity, specificity, confidence intervals) and validation status. We also propose minimum reporting standards for study design, pre-analytical variables, and statistical rigor, modeled on REMARK guidelines. A roadmap for biomarker validation and a cross-fluid comparison matrix are provided to guide future research. Despite considerable progress, significant challenges remain, including biological heterogeneity, pre-analytical variability, and insufficient external validation. Future efforts should prioritize multicenter prospective studies, assay harmonization, ethical frameworks for early diagnosis, and integration of emerging technologies such as artificial intelligence and digital twins. Fluid-based biomarkers, while not yet replacing clinical evaluation, are essential tools for accelerating drug development, enabling patient stratification, and moving toward personalized medicine in ALS.

ID: 42219390
Title: A Conjugate of Aminoadamantane and Tetrahydro-γ-Carboline Inhibits Accumulation of Mutant α-Synuclein A53T in the Cellular Model of Proteinopathy.
Abstract: Pathological aggregation of α-synuclein is a key event in the development of synucleinopathies, such as Parkinson's disease and Lewy body dementia. Currently, no effective disease-modifying therapy is available, necessitating the search for new therapeutic agents. One promising strategy involves the use of low-molecular-weight compounds capable of inhibiting the formation of toxic protein aggregates. This study evaluates the anti-aggregation properties of EC3222x, a conjugate of pharmacophoric fragments of amantadine and a fluorinated derivative of tetrahydro-γ-carboline. α-Synucleinopathy was modeled in the SH-SY5Y neuroblastoma cell line by transfection with a plasmid vector encoding the mutant human α-synuclein A53T protein. EC3222x at a concentration of 1 µM reduced the number of cells with α-synuclein A53T aggregates. Its efficacy was comparable to that of SynuClean-D and Buntanetap, known inhibitors of α-synuclein aggregation. Treatment with EC3222x reduced both the level of diffusely distributed intracellular α-synuclein and the formation of mature fibrillar aggregates and large aggresomes. Importantly, EC3222x did not affect the accumulation of another aggregation-prone protein, TDP-43, in a similar cellular model, indicating its specificity for α-synuclein. These findings suggest that EC3222x may represent a promising candidate for the development of therapeutic agents targeting synucleinopathies.

ID: 42234776
Title: Cryptic splicing in synaptic and membrane excitability genes links TDP-43 loss to neuronal dysfunction.
Abstract: TAR DNA binding protein 43 (TDP-43) pathology is a defining pathological hallmark of multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A major feature of TDP-43 pathology is its nuclear depletion, leading to the aberrant inclusion of cryptic exons during RNA splicing. STMN2 and UNC13A have emerged as prominent TDP-43 splicing targets, but the broader impact of TDP-43-dependent cryptic splicing on neuronal function remains unclear. Here, we report previously unidentified TDP-43 splicing targets critical for membrane excitability and synaptic function, including KALRN, RAP1GAP, SYT7, and KCNQ2. Using human stem cell-derived neurons, we showed that TDP-43 reduction induces cryptic splicing and down-regulation of these genes, resulting in impaired excitability and synaptic transmission. In postmortem brains from patients with FTD, these cryptic splicing events occurred selectively in neurons with TDP-43 pathology. Suppressing individual cryptic splicing events using antisense oligonucleotides partially restored neuronal function, and combined targeting almost fully rescued the synaptic deficit caused by TDP-43 loss. Together, our findings provide evidence that cryptic splicing in these synaptic and membrane excitability genes is not only a downstream marker but instead a direct driver of neuronal dysfunction, establishing a mechanistic link between TDP-43 pathology and neurodegeneration in ALS and FTD.

ID: 42248860
Title: TDP-43 oxidation and PP1 crosstalk at RNA granule-mitochondria contact sites.
Abstract: Inter-organelle contact sites are key hubs for organelle bidirectional crosstalk. However, how mitochondria and RNA granules interact at contact sites and its regulation by mitochondrial oxidative phosphorylation (OXPHOS) remain unclear. Here, using Super-Resolution live microscopy, we identify RNA granule-mitochondria contact site formation in OXPHOS conditions. Reactive oxygen species (ROS) generated by mitochondrial OXPHOS promotes TDP-43 localization to cytoplasmic RNA granules via TDP-43 cysteine oxidation at Cys173/Cys175. Mechanistically, RNA granule-mitochondria contact tethering is mediated by TDP-43 on RNA granules binding to GADD34 on mitochondria, while contact untethering is regulated by TDP-43 oxidation. Functionally, this allows for GADD34 and its binding partner PP1 to regulate TDP-43 RNA granule dynamics, and conversely, for TDP-43 oxidation to regulate the ability of the phosphatase PP1 to form granules. Finally, disease-associated mutant TDP-43 misregulates this pathway, ultimately leading to PP1 granules lacking TDP-43. This dynamic crosstalk between TDP-43 oxidation and PP1 has significant consequences for TDP-43-associated diseases including Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD).

ID: 42251967
Title: PBMC DEG/miRNA biomarkers of TDP-43 pathology in ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) lacks reliable, disease-specific, and minimally invasive biomarkers, representing a major barrier to early diagnosis and patient stratification. The primary aim of this translational pilot study was to identify a disease-specific, TDP-43-related, gene-microRNA (miRNA) signature in peripheral blood mononuclear cells (PBMCs) of ALS patients with potential diagnostic value. To this end, we first identified differentially expressed disease-specific genes (dsDEGs) using a TDP-43-based rat model of ALS, generated by stereotaxic infusion of full-length (FL) TAR DNA-binding protein 43 (TDP-43) into the motor cortex. Transcriptomic profiling of the motor cortex revealed candidate dsDEGs, which were subsequently validated by RT-qPCR in motor cortex, spinal cord, and PBMCs from the same animals. To assess translational relevance, expression levels of these dsDEGs were analyzed in PBMCs from early- to mid-stage ALS patients and matched healthy controls, while disease specificity was evaluated using Parkinson's disease (PD) samples. In parallel, conserved miRNAs predicted to target the identified dsDEGs were examined in both rat and human PBMCs. Five dsDEGs, Mctp1, Penk, Mt2A, Drd1, and Rasgrp2, were consistently dysregulated across central and peripheral tissues in the TDP-43 rat model. RT-qPCR analysis of human PBMCs confirmed significant and selective dysregulation of these genes in ALS, but not in PD, supporting disease specificity. Moreover, exposure of human neuroblastoma cells and healthy PBMCs to TDP-43 recapitulated the ALS-like expression changes. Computational and experimental analyses identified seven conserved miRNAs targeting these dsDEGs, of which four were significantly downregulated in ALS PBMCs, supporting a coordinated regulatory network. Receiver operating characteristic (ROC) analyses demonstrated strong discriminative performance for both the gene signature (AUC 0.87-1.00) and the associated miRNAs (AUC 0.95-1.00). Together, these findings define a novel PBMC-based gene-miRNA signature that mirrors central ALS pathology and shows high diagnostic accuracy and disease specificity, highlighting its potential as a minimally invasive biomarker for ALS.

ID: 42264399
Title: Human TDP-43 expression worsens FTD-related phenotypes in progranulin-insufficient mice.
Abstract: Loss-of-function progranulin (GRN) mutations cause frontotemporal dementia with TDP-43 pathology (FTD-TDP). Nearly all pathogenic GRN mutations cause progranulin haploinsufficiency, but it is unclear how progranulin insufficiency causes FTD-TDP. To address this question, we crossed progranulin-insufficient mice with a human TDP-43 transgenic mouse line (RRID:IMSR_JAX:012836) in which homozygous mice (hTDP++) develop TDP-43 aggregates at an early age, but hemizygous mice (hTDP+) do not develop TDP-43 aggregates. We therefore analyzed the effects of progranulin insufficiency on both hTDP+ and hTDP++ mice. Progranulin insufficiency did not induce TDP-43 aggregation in hTDP+ mice, but interacted with hTDP expression to worsen FTD-related phenotypes. Grn+/-:hTDP+ mice exhibited more dramatic impairment of social dominance than either Grn+/- or hTDP+ mice, which was associated with combined effects of progranulin insufficiency and hTDP expression on dendritic spines of neurons in the medial prefrontal cortex (mPFC). Despite a lack of TDP-43 aggregation, progranulin insufficiency altered the RNA splicing events induced by hTDP overexpression in frontal cortex of hTDP+ mice. Progranulin insufficiency also did not alter TDP-43 aggregation in hTDP++ mice, but Grn-/-:hTDP++ mice exhibited an abnormal neuroinflammatory response characterized by increased markers of disease-associated microglia and signs of an impaired adaptive immune response. These results highlight dysfunction of mPFC neurons as a potential mechanism of behavioral changes in FTD-GRN and implicate dysregulated inflammation as a potential driver of disease progression in FTD-GRN.

ID: 42302780
Title: A CRISPR knockout mouse library for functional genomics in influenza research.
Abstract: Functional validation of host factors in whole-animal models is a major bottleneck in virology; it hinders the translation of data from in vitro studies into a deeper understanding of the viral life cycle and pathogenesis. To address this challenge, we developed a systematic in vivo screening platform for influenza A virus. This platform comprises a library of 84 CRISPR-Cas9-generated gene-modified mouse lines targeting host factors prioritized from the literature and in vitro small interfering RNA (siRNA) screening studies. Using this resource, we identified 17 host factors whose genetic ablation conferred resistance to influenza A virus infection. Further studies of two of these factors, Arhgef28 and Lasp1, revealed distinct protective mechanisms against influenza A virus. We offer this mouse library to the research community as a powerful platform for studying virus-host interactions in a physiologically relevant context.

ID: 42341041
Title: IRE1 regulates the proteostasis of TDP-43/TARDBP in ALS/FTD through ribosome-associated quality control.
Abstract: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are progressive neurodegenerative disorders characterized by motor neuron degeneration, leading to muscle weakness, atrophy, and cognitive impairments. A defining pathological hallmark of ALS/FTD is the cytosolic mislocalization and accumulation of TAR DNA-binding protein 43 (TDP-43), highlighting its critical role in ALS pathogenesis. However, the molecular mechanisms underlying TDP-43 proteostasis remain poorly understood. Through a genetic screening approach, we identify inositol-requiring enzyme 1 (IRE1), an endoplasmic reticulum-resident transmembrane protein, as a potent suppressor of TDP-43 protein levels. Furthermore, we show that ribosome-associated quality control (RQC) factors play a crucial role in regulating TDP-43 proteostasis and cellular toxicity. Activation of the RQC pathway prevents excessive accumulation of TDP-43 and associated toxicity. Mechanistically, our findings suggest that IRE1 regulates TDP-43 protein level by promoting the degradation of aberrant TDP-43 translation product through the RQC pathway. IRE1 acts canonically to enhance the transcription of the RQC core component Clbn/NEMF and noncanonically to physically interact with Clbn/NEMF, thereby ameliorating TDP-43-induced proteotoxicity. Moreover, ectopic expression or pharmacological activation of IRE1 alleviates TDP-43 pathology and restores cognitive function in the TDP-43 A315T ALS mouse models. Collectively, our study identifies a role for IRE1 in the translational quality control of TDP-43 and establishes its potential as a therapeutic target for ALS/FTD.

ID: 42341118
Title: Isoform-specific steric zippers drive aberrant assembly and mislocalization of shortened TDP-43.
Abstract: Prion-like domain (PrLD)-mediated aggregation and concomitant dysfunction of the essential RNA-binding protein transactive response (TAR) DNA-binding protein of 43 kilodaltons (TDP-43) is a common feature of multiple debilitating neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). However, shortened TDP-43 (sTDP-43) splice isoforms where the PrLD is largely replaced by an 18-residue carboxyl-terminal tail also contribute to ALS pathophysiology and are enriched in motor neurons. Curiously, despite lacking most of the PrLD, sTDP-43 exhibits pronounced insolubility in cells and tissue of patients with ALS. Here, we establish that the short, isoform-specific carboxyl-terminal tail of sTDP-43 confers high aggregation propensity, which is encoded by two clusters of steric zippers, and can be mitigated by short RNA chaperones. Disrupting these zippers enhances sTDP-43 solubility at the pure protein level and in neurons. Notably, these steric zippers, rather than a predicted nuclear export signal in the carboxyl-terminal tail, drive cytoplasmic mislocalization and aggregation of sTDP-43 in neurons. Thus, we define the sequence-encoded determinants of aberrant sTDP-43 assembly and provide mechanistic insights into sTDP-43 disease pathology.

ID: 42353079
Title: Loss of TDP-43 Drives Innate Immune Activation Through Relish in Drosophila.
Abstract: Inflammatory and immune alterations are increasingly recognized as components of ALS pathology, yet whether they arise as a direct consequence of TDP-43 dysfunction or as a downstream response to neurodegeneration remains unresolved. To address this question, we profiled adult head transcriptomes of Drosophila lacking TBPH, the fly homolog of TDP-43, and identified marked overactivation of the conserved Toll/Imd/NF-κB (Relish) innate immune pathway, including increased expression of antimicrobial effector genes and inflammatory genes. We further found that TDP-43/TBPH regulates the NF-κB homolog Relish by associating with its mRNA and that its loss permits Relish-dependent immune overactivation. Genetic reduction in Relish in TDP-43-deficient flies suppressed inflammatory signaling and ameliorated neurological defects in vivo, indicating that immune dysregulation contributes to TDP-43 loss-associated phenotypes.

ID: 42383305
Title: TDP-43 proteinopathy as a biomarker and therapeutic target in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is the most common form of adult-onset motor neuron disease, characterised by the degeneration of upper and lower motor neurons. The cytoplasmic aggregation of TDP-43 (TAR DNA-binding protein 43), an RNA-binding protein, is considered a hallmark of ALS pathology, found in nearly all postmortem cases of ALS. TDP-43 is normally primarily nuclear, where it has a widespread role in gene regulation. Mutations, extrinsic stressors, and alterations in RNA homeostasis in ALS lead to nuclear depletion of TDP-43 and the formation of cytosolic TDP-43 aggregates. This causes multiple downstream effects on neuronal function and degeneration as well as gene expression. TDP-43 is a promising target as a biomarker, as it is found to be elevated in the biofluids of ALS patients, and its cytoplasmic aggregation can also be observed in peripheral tissues; however, methodological variability and technical limitations currently preclude the establishment of TDP-43 as a standalone biomarker. There are also promising therapeutic strategies in development targeting TDP-43 pathology, but a critical challenge that remains is achieving a balance between eliminating toxic aggregates and preserving the essential functions of TDP-43. In summary, with further research, considering TDP-43 pathology in ALS gives hope for finding future novel diagnostics and therapeutics for ALS.

ID: 42395430
Title: ADAR2-Mediated RNA Editing Promotes TDP-43 Nuclear Export and Alters RNA Binding.
Abstract: TAR DNA binding protein - 43 (TDP-43) nuclear loss is a pathological hallmark of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and related neurodegenerative disorders. While the consequences of TDP-43 dysfunction have been well-characterized, the mechanisms driving TDP-43 mislocalization remain poorly understood. Previous observations of altered localization and function of the adenosine-to-inosine (A-to-I) RNA editing enzyme adenosine deaminase acting on RNA 2 (ADAR2) in ALS/FTD tissue prompted us to investigate whether dysregulated RNA editing contributes to pathological TDP-43 nucleocytoplasmic trafficking. TDP-43 cytoplasmic mislocalization was assessed following ADAR2 and TDP-43 co-overexpression in HEK293T cells and a Drosophila model co-overexpressing human TDP-43 and dADAR in motor neurons. We further evaluated TDP-43 mislocalization through both HeLa cell assays and interspecies heterokaryon assays. Next, we assessed TDP-43 binding to A-to-I edited RNA oligomers through electrophoretic mobility shift assays (EMSAs), and investigated inosine-containing RNAs in vivo via TDP-43 RNA immunoprecipitation followed by sequencing (RIP-seq) datasets from human TDP-43-expressing Drosophila . Finally, RNAseq and enhanced cross-linking and immunoprecipitation (eCLIP-seq) were performed in SH-SY5Y cells overexpressing three ADAR2 variants with differing editing activity to identify editing-related transcriptional alterations and RNAs differentially bound to TDP-43. ADAR2 overexpression reduced the nucleocytoplasmic (N:C) ratio of TDP-43 in HEK293T cells in a ADAR2 catalytic activity- and TDP-43 RNA-binding capacity-dependent manner. Drosophila motor neurons overexpressing dADAR also exhibited decreased nuclear TDP-43. Interspecies heterokaryons and permeabilized HeLa cell assays demonstrated that catalytically active ADAR2 and synthetic inosine-containing RNA oligomers, respectively, enhance nuclear export of endogenous TDP-43. EMSAs revealed preferential binding of TDP-43 to inosine-containing RNAs relative to unedited RNAs, and analysis of Drosophila RIP-seq datasets demonstrated enrichment of edited transcripts within TDP-43-bound RNAs. Finally, RNAseq and eCLIP-seq analyses identified editing-dependent alterations in gene expression and TDP-43 RNA-binding profiles in SH-SY5Y cells overexpressing active ADAR2 variants. Together, our findings identify A-to-I RNA editing as a previously unrecognized regulator of TDP-43 localization and RNA interactions. These results support a model where altered RNA editing modifies TDP-43-RNA interactions, promoting increased nuclear export of TDP-43. Broadly, our work highlights RNA editing dysregulation as a potential contributor to early pathogenic mechanisms underlying TDP-43 proteinopathies.

ID: 42399370
Title: Therapeutic targeting of the conserved region within the low-complexity domain of TDP-43 is neuroprotective and extends survival in amyotrophic lateral sclerosis mice.
Abstract: Autosomal dominant mutations in TARDBP, encoding TAR DNA-binding protein 43 (TDP-43), cause amyotrophic lateral sclerosis (ALS), and TDP-43 pathology is a hallmark of multiple aging-associated neurodegenerative diseases. Despite its pathological role, effective therapies remain limited by the lack of safe, potent molecules targeting TDP-43 neurotoxicity. Here we show that the conserved α-helical region spanning residues 320-340 (conserved region or CR) is a therapeutically actionable target for TDP-43 neurotoxicity. Deletion of CR markedly suppressed TDP-43-induced neuronal death. Structure-based virtual screening identified XL20, a brain-penetrant small molecule that engages CR and confers neuroprotection without affecting TDP-43 splicing activity. XL20 alleviated motor neuron loss, extended survival in TDP-43 p.Ala315Thr ALS mice and enhanced neuronal function in p.Gln331Lys induced pluripotent stem cell-derived human ALS motor neurons. Mechanistically, targeting CR suppressed TDP-43 mitochondrial localization and restored mitochondrial function, likely through liquid-liquid phase separation. Our findings highlight CR as a therapeutic target for TDP-43-associated neurodegeneration and support CR-binding small molecules as therapeutic candidates.

ID: 42404433
Title: Beyond motor neurons: peripheral TDP-43 pathology in skeletal muscle and intramuscular nerves in amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis is a progressive neurodegenerative disease characterized by accumulation of the 43-kDa TAR DNA-binding protein (TDP-43). This neuropathological signature has been well documented within the CNS; however, recent findings indicate that the phosphorylated TDP-43 additionally deposits in peripheral tissues, including skeletal muscle and intramuscular nerves. These data warrant a change of view from a neurocentric perspective of amyotrophic lateral sclerosis pathogenesis towards a broader concept of TDP-43 proteinopathy extending both within and beyond the nervous system. In this review, we focus on current evidence supporting the presence of TDP-43 pathology in amyotrophic lateral sclerosis skeletal muscle, examining its topographic distribution, molecular characteristics and associations with intramuscular nerve bundles. We also discuss the susceptibility of intrinsic muscle cells, disrupted axonal transport and impairment in protein quality control. Phosphorylated TDP-43 pathology in muscle biopsies from amyotrophic lateral sclerosis patients has emerged as a promising tool in the early diagnosis of the disease. Moreover, we discuss the relevance of these findings to amyotrophic lateral sclerosis pathogenesis and potential therapeutic implications.

ID: 42431556
Title: Fisetin prevents deterioration of cellular functions in amyotrophic lateral sclerosis variants G262R and P438L of SQSTM1 in SH-SY5Y cells.
Abstract: Oxidative stress is widely accepted as one of the important factors contributing to neurodegeneration, leading to fatal neurodegenerative diseases (NDD) such as Amyotrophic Lateral Sclerosis. Since flavonoids possess antioxidant properties, we investigated whether Fisetin (FS) and Quercetin (QR) protected cells from oxidative stress arising from pathogenic mutations G262R (G > A) and P438L (C > T) of SQSTM1 found in Indian ALS patients. SQSTM1 codes for p62 protein and is involved in multiple signaling pathways through its various domains. We studied changes in cell viability and cellular functions using immunoblotting, confocal microscopy, immunoprecipitation and FACS analysis in the presence and absence of FS and QR. Supplementation with FS and QR in SH-SY5Y cells expressing SQS-wild type and mutants increased cell viability and decreased ROS formation. Also, Nrf2 protein levels increased to offset oxidative stress response. In addition, we studied the effect of FS on the nuclear-cytoplasmic distribution of TDP-43 protein, which serves as a hallmark for ALS. FS corrected the nuclear-cytoplasm translocation of TDP-43 protein and decreased late apoptosis in mutants. Our study illustrates that both FS and QR shield cells from oxidative stress, and that FS imparted better protection against the pathogenic effect of SQSTM1 mutants in SH-SY5Y neuronal cells.

ID: 42479840
Title: The ARHGAP32 isoform PX-RICS is specifically targeted to inhibitory synapses by binding to gephyrin.
Abstract: Precise regulation of excitatory-inhibitory balance is critical for neural circuit function, and its disruption underlies neurodevelopmental disorders such as autism spectrum disorder (ASD) and epilepsy. PX-RICS, a major ARHGAP32 splice variant enriched at inhibitory synapses, has been linked to cognitive dysfunctions; however, the molecular basis of its synaptic targeting and function remains unknown. Here, we identify gephyrin as the primary synaptic anchor for PX-RICS and determine the 2.2 Å crystal structure of their complex. Our structural analysis reveals that the N-terminal gephyrin-binding region (GBR) engages gephyrin E-domain through conserved hydrophobic interactions, explaining the isoform-specific targeting of PX-RICS (but not RICS) to inhibitory synapses. This binding interface overlaps with the neurotransmitter receptor binding site on gephyrin, suggesting a competitive yet dynamic interaction landscape among these inhibitory synaptic proteins. Arhgap32ΔGBR mice exhibit key features of ARHGAP32-related disorders, including impaired social novelty recognition and increased seizure susceptibility, indicating that gephyrin-mediated anchoring is critical for PX-RICS to function in inhibitory synapses.

ID: 42508540
Title: R-loops: Biological functions, regulatory mechanisms, and therapeutic implications in brain diseases-A review.
Abstract: R-loops are three-stranded nucleic acid structures formed by a DNA-RNA hybrid and a displaced single-stranded DNA. They regulate transcription, replication, and DNA repair, but their dysregulation causes genomic instability and inflammation, contributing to brain diseases. The nervous system exhibits selective vulnerability to R-loop stress due to ultra-long gene transcription, post-mitotic longevity, and high metabolic demands. This review synthesizes current literature from PubMed, Scopus, Web of Science, and Embase (2010-2026) on R-loop biology, with a focus on brain-specific mechanisms, regulatory factors (SETX, ZPR1, METTL3, TDP-43/FUS), and disease models. In neurodegeneration, R-loop accumulation drives repeat expansion disorders (Fragile X, Huntington's disease) and loss-of-function SETX mutations (AOA2), whereas gain-of-function SETX (L389S) causes pathological R-loop depletion in ALS4, disrupting TGF-β signaling. TDP-43/FUS and SMN are integral to R-loop resolution, unifying ALS/FTD and SMA. In brain cancers, METTL3-mediated m6A modification of TERRA stabilizes telomeric R-loops in ALT-positive neuroblastoma, creating a therapeutic vulnerability to METTL3 inhibitors (STM2457, STC-15). Glioma stem cells rely on m6A-modified circPOLR2B to regulate R-loop formation and malignancy. Clinical-stage agents (EP102, TUG1ASO, ATX-559) and R-loop-derived prognostic signatures (RLPI) are emerging, but translation is hindered by a lack of non-invasive biomarkers and the dual physiological/pathological roles of R-loops. R-loops are central to brain disease pathogenesis, offering promising therapeutic targets. Future research should prioritize precision R-loop modulators, non-invasive biomarkers, and combinatorial strategies.

ID: 42541567
Title: Targeting TDP-43 in sporadic amyotrophic lateral sclerosis.
Abstract: Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder characterized by motor neuron degeneration leading to early mortality. Despite advances in understanding genetic and molecular contributors, effective disease-modifying therapies for sporadic ALS are of limited utility. The identification of the accumulation of TAR DNA-binding protein 43 (TDP-43) in 97% of total ALS cases represents a critical pathogenic hallmark. This review examines key biological mechanisms underlying TDP-43 pathology, emerging therapeutic strategies, and evolving approaches to clinical trial design and biomarker development. TDP-43 loss of nuclear function, leading to widespread RNA missplicing, and inclusion of cryptic exons, represents an early and critical event in ALS pathogenesis causing downstream dysregulation of key neuronal genes such as STMN2 and UNC13A contributing to axonal degeneration and synaptic dysfunction. Therapeutic strategies targeting these pathways are currently under investigation. Additional approaches aim to ameliorate TDP-43 gain-of-function through cytoplasmic TDP-43 aggregation or modulating processes such as stress responses and RNA metabolism, although clinical translation has been challenging. Advances in biomarkers, including neurofilament light chain and cryptic exon-derived peptides, provide tools for developing efficient clinical trials. However, heterogeneity in disease progression and limitations of available clinical endpoints complicate trial design. Integration of biological insights with biomarker-driven patient stratification and optimized trial methodologies is essential to improve clinical trial outcomes. Emerging biomarkers may enable earlier diagnosis, monitoring of therapeutic response, and personalized treatment approaches. Continued alignment of biological discovery with innovative clinical trial design holds promise for advancing effective therapies and transforming the future of ALS.