ID: 22932872
Title: Autophagy activators rescue and alleviate pathogenesis of a mouse model with proteinopathies of the TAR DNA-binding protein 43.
Abstract: TDP-43 is a multifunctional DNA/RNA-binding protein that has been identified as the major component of the cytoplasmic ubiquitin (+) inclusions (UBIs) in diseased cells of frontotemporal lobar dementia (FTLD-U) and amyotrophic lateral sclerosis (ALS). Unfortunately, effective drugs for these neurodegenerative diseases are yet to be developed. We have tested the therapeutic potential of rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR) and three other autophagy activators (spermidine, carbamazepine, and tamoxifen) in a FTLD-U mouse model with TDP-43 proteinopathies. Rapamycin treatment has been reported to be beneficial in some animal models of neurodegenerative diseases but not others. Furthermore, the effects of rapamycin treatment in FTLD-U have not been investigated. We show that rapamycin treatment effectively rescues the learning/memory impairment of these mice at 3 mo of age, and it significantly slows down the age-dependent loss of their motor function. These behavioral improvements upon rapamycin treatment are accompanied by a decreased level of caspase-3 and a reduction of neuron loss in the forebrain of FTLD-U mice. Furthermore, the number of cells with cytosolic TDP-43 (+) inclusions and the amounts of full-length TDP-43 as well as its cleavage products (35 kDa and 25 kDa) in the urea-soluble fraction of the cellular extract are significantly decreased upon rapamycin treatment. These changes in TDP-43 metabolism are accompanied by rapamycin-induced decreases in mTOR-regulated phospho-p70 S6 kinase (P-p70) and the p62 protein, as well as increases in the autophagic marker LC3. Finally, rapamycin as well as spermidine, carbamazepine, and tamoxifen could also rescue the motor dysfunction of 7-mo-old FTLD-U mice. These data suggest that autophagy activation is a potentially useful route for the therapy of neurodegenerative diseases with TDP-43 proteinopathies.

ID: 26828926
Title: Spermine inhibits Endoplasmic Reticulum Stress-induced Apoptosis: a New Strategy to Prevent Cardiomyocyte Apoptosis.
Abstract: Endoplasmic reticulum stress (ERS) plays an important role in the progression of acute myocardial infarction (AMI), in part by mediating apoptosis. Polyamines, including putrescine, spermidine, and spermine, are polycations with anti-oxidative, anti-aging, and cell growth-promoting activities. This study aimed to determine the mechanisms by which spermine protects against ERS-induced apoptosis in rats following AMI. AMI was established by ligation of the left anterior descending coronary artery (LAD) in rats, and exogenous spermine was administered by intraperitoneal injection (2.5 mg/ml daily for 7 days pre-AMI). Spermine treatment limited infarct size, attenuated cardiac troponin I and creatinine kinase-MB release, improved cardiac function, and decreased ERS and apoptosis related protein expression. Isolated cardiomyocytes subjected to hypoxia showed significant increase in reactive oxygen species (ROS) and the expression of apoptosis and ERS related proteins; these effects occurred through PERK and eIF2α phosphorylation. The addition of spermine attenuated cardiomyocyte apoptosis, suppressed the production of ROS, and inhibited ERS related pathways. Spermine was an effective pre-treatment strategy to attenuate cardiac ERS injury in rats, and the cardioprotective mechanism occurring through inhibition of ROS production and down regulation of the PERK-eIF2α pathway. These findings provide a novel target for the prevention of apoptosis in the setting of AMI.

ID: 33705388
Title: MARK2 phosphorylates eIF2α in response to proteotoxic stress.
Abstract: The regulation of protein synthesis is essential for maintaining cellular homeostasis, especially during stress responses, and its dysregulation could underlie the development of human diseases. The critical step during translation regulation is the phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α). Here we report the identification of a direct kinase of eIF2α, microtubule affinity-regulating kinase 2 (MARK2), which phosphorylates eIF2α in response to proteotoxic stress. The activity of MARK2 was confirmed in the cells lacking the 4 previously known eIF2α kinases. MARK2 itself was found to be a substrate of protein kinase C delta (PKCδ), which serves as a sensor for protein misfolding stress through a dynamic interaction with heat shock protein 90 (HSP90). Both MARK2 and PKCδ are activated via phosphorylation in proteotoxicity-associated neurodegenerative mouse models and in human patients with amyotrophic lateral sclerosis (ALS). These results reveal a PKCδ-MARK2-eIF2α cascade that may play a critical role in cellular proteotoxic stress responses and human diseases.

ID: 41177462
Title: Nasal-to-brain siRNA delivery based on trace amine associated receptor for improving cognitive function.
Abstract: Gene-based therapies for central nervous system (CNS) disorders face substantial challenges in overcoming the blood-brain barrier (BBB) to effectively target brain tissues. The nasal-to-brain delivery route has gained increasing attention as it bypasses the BBB, facilitating faster drug delivery to the lesion site while minimizing systemic side effects. Here, we developed a nasal-to-brain delivery system to administer small interfering RNA (siRNA) for the treatment of radiation-induced brain injury (RBI). RNA sequencing revealed that the p53 signaling pathway was predominantly enriched in the hippocampus, with significant upregulation of Alox12B expression in RBI mice. To improve the delivery of siRNA targeting Alox12B, we engineered spermidine-modified ginseng-derived extracellular vesicles (S-GEVs) nanoparticles, termed S-GEVs@siRNA. These nanoparticles leveraged the targeting capabilities of spermidine for olfactory receptor-trace amine associated receptor (TAAR), enhancing siRNA delivery and therapeutic efficacy. After intranasal administration, the nanoparticles were efficiently internalized by olfactory receptor neurons (ORNs) via the olfactory nerve pathway. The nanoparticles then escaped lysosomes, releasing siRNA into the cytoplasm, leading to gene downregulation and therapeutic benefits. Our results demonstrated that the designed nanoparticles were absorbed by the ORNs labeled with the Olfactory Marker Protein (OMP) and TAAR5 and successfully entered the olfactory bulb and the brain. Treatment with these nanoparticles significantly reduced p53-mediated neuronal ferroptosis and improved synaptic function both in vitro and in vivo. In conclusion, S-GEVs@siRNA nanoparticles rapidly reached the olfactory bulb through TAAR-mediated endocytosis, entered hippocampal neurons, downregulated Alox12B expression, exerted neuroprotective effects, and alleviated RBI-induced cognitive dysfunction. The designed nasal-to-brain delivery system holds great promise for treating various CNS diseases.

ID: 41231952
Title: MARK2 regulates C9orf72 repeat-associated non-AUG translation.
Abstract: Protein homeostasis is exquisitely regulated through processes involving protein synthesis essential for cellular health and disease prevention. Repeat-associated non-AUG (RAN) translation at expanded GGGGCC repeats in the C9orf72 gene produces dipeptide repeat (DPR) proteins that are implicated in amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). However, the mechanisms promoting this noncanonical translation remain incompletely understood. Here, we identify microtubule affinity-regulating kinase 2 (MARK2) as a key eIF2α kinase that enhances RAN translation under proteotoxic stress. We show that MARK2-eIF2α signaling, activated by misfolded proteins including DPRs and TDP-43, is upregulated in C9-ALS patient tissues. Loss of MARK2 significantly suppresses RAN translation in reporter cells, patient-derived neurons, and a mouse model and confers neuroprotection under proteotoxic conditions. These findings position MARK2 as a critical stress-sensing cytosolic regulator that promotes repeat-associated noncanonical translation and associated toxicity.

ID: 41430470
Title: Axonal Eif5a hypusination controls local translation and mitigates defects in FUS-ALS.
Abstract: Local protein synthesis is vital for neuronal function, but its dysregulation in neurodegenerative diseases remains poorly defined. Here we applied spatial transcriptomics to adult mouse motor nerve axons and cell bodies to enable subcellular mapping. Among transcripts found in mature axons, the most enriched biological process is protein translation, and localization of translation machinery was confirmed using multiplexed single-molecule spatial transcriptomics combined with immunofluorescence. Amyotrophic lateral sclerosis (ALS)-associated mutations in the RNA-binding protein fused in sarcoma (FUS), which suppress local translation, disrupt the compartment-specific RNA signatures, including components of the translation machinery. In particular, eukaryotic initiation factor 5a (Eif5a), a translation factor involved in elongation and termination, is found to be locally impaired in mutant FUS axons with reduced levels of its active hypusinated form. Axon-specific treatment with polyamine spermidine restores Eif5a hypusination and ameliorates mutant FUS-dependent neuronal defects, including suppression of local protein synthesis. Finally, in vivo spermidine treatment reduces ALS-related toxicity in mutant FUS and TDP-43 Drosophila models, which may have implications for therapy development.

ID: 42441693
Title: Cardiac Autonomic Dysfunction and Sudden Cardiac Death in Amyotrophic Lateral Sclerosis: Clinical Implications and Considerations for Care.
Abstract: Amyotrophic lateral sclerosis (ALS) is traditionally viewed as a motor neuron disease that progresses from muscular weakness to respiratory failure and death. Increasing evidence, however, demonstrates clinically meaningful involvement of the autonomic nervous system, particularly in cardiovascular regulation. This narrative review synthesizes current evidence on the mechanisms, clinical implications, and palliative considerations of cardiac autonomic dysfunction in ALS, with particular emphasis on its relationship to sudden cardiac death (SCD). Cardiac autonomic dysfunction is increasingly recognized as a significant contributor to disease burden in ALS, manifesting as abnormalities in heart rate variability, sympathetic overactivity, and corrected QT prolongation. These derangements may contribute to malignant arrhythmias, increasing susceptibility to SCD in combination with respiratory decline. Epidemiologic data suggest that SCD accounts for a meaningful proportion of ALS-related mortality, although it is likely underrecognized due to misclassification and lack of routine cardiac monitoring. Clinical implications include the need for improved risk stratification and earlier detection of autonomic dysfunction using accessible markers, such as electrocardiographic indices, orthostatic vital signs, and ambulatory monitoring. Emerging technologies, including wearable biosensors, may further enhance longitudinal assessment. These considerations also have direct relevance for advanced care planning, as ALS may involve unpredictable and abrupt cardiac death in addition to progressive respiratory decline. Recognizing ALS as a multisystem disorder with significant cardiac involvement supports the integration of structured cardiovascular monitoring into multidisciplinary care models and highlights the need for prospective studies to guide standardized management strategies.

ID: 42461445
Title: Metabolomic analyses of amyotrophic lateral sclerosis, muscle cramps, and TJ-68 treatment.
Abstract: Most patients with amyotrophic lateral sclerosis (ALS), a fatal motor neuron disease, experience painful muscle cramps. Our recent pilot trial of the Japanese Kampo medicine TJ-68 suggested its efficacy in improving muscle cramps in patients with ALS. This study analyzed plasma metabolomic changes to identify the underlying mechanisms of muscle cramps in ALS and the effects of TJ-68. Plasma was obtained from 11 participants with ALS in the repeated crossover trial at five time points (baseline, two placebo phases, and two TJ-68 phases). Metabolites were analyzed using mass spectrometry. Linear mixed-effects models were applied to identify metabolite changes associated with muscle cramps, determine the effects of TJ-68 on metabolites, and predict which participants would respond to TJ-68. Higher glutamine/glutamate, arginine, and leucine levels were associated with more severe muscle cramps. TJ-68 treatment increased tryptophan and aconitate levels but reduced serotonin and acetylcarnitine levels. Long-chain acylcarnitine levels were correlated with muscle cramp severity, and their levels tended to decrease with treatment. Uric acid, β-aminoisobutyric acid, α-aminoadipic acid, and acetylcholine emerged as predictors of the efficacy of TJ-68. This study identified the metabolite profile of muscle cramps in ALS and the changes in metabolite levels after TJ-68 treatment. Several baseline metabolites were associated with the prediction of the response to muscle cramps following TJ-68 treatment. Uric acid might be particularly useful because of its easy measurement in standard assays. Our study affirms the value of metabolomic technology for future pharmacotherapy and studies in ALS.