bims-axbals Biomed News
on Axonal Biology and ALS
Issue of 2024‒05‒05
twenty-two papers selected by
TJ Krzystek, ALS Therapy Development Institute
  1. CK1δ/ε kinases regulate TDP-43 phosphorylation and are therapeutic targets for ALS-related TDP-43 hyperphosphorylation.
  2. Disease related changes in ATAC-seq of iPSC-derived motor neuron lines from ALS patients and controls.
  3. Skeletal muscle dysfunction in amyotrophic lateral sclerosis: a mitochondrial perspective and therapeutic approaches.
  4. An integrative miRNA-mRNA expression analysis identifies miRNA signatures associated with SOD1 and TARDBP patient-derived motor neurons.
  5. Mutation of the ALS/FTD-associated RNA-binding protein FUS affects axonal development.
  6. Glucose hypometabolism prompts RAN translation and exacerbates C9orf72-related ALS/FTD phenotypes.
  7. Small peptide CSF fingerprint of amyotrophic lateral sclerosis.
  8. Monocytes prevent apoptosis of iPSCs and promote differentiation of kidney organoids.
  9. Context-specific stress causes compartmentalized SARM1 activation and local degeneration in cortical neurons.
  10. Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions.
  11. Generation of 3D-Multicellular Human iPSC-Heart Organoids for the Noninvasive Assessment of Cardiac Fibrosis.
  12. Mature neurons from iPSCs unveil neurodegeneration-related pathways in mucopolysaccharidosis type II: GSK-3β inhibition for therapeutic potential.
  13. Nuclear and degradative functions of the ESCRT-III pathway: implications for neurodegenerative disease.
  14. eIF4G as a switch for heat shock mRNA translation.
  15. Proteomic analysis reveals a potential role for extracellular vesicles within the erythroblastic island niche.
  16. Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle.
  17. sFlt-1 Impairs Neurite Growth and Neuronal Differentiation in SH-SY5Y Cells and Human Neurons.
  18. Plasma neurofilament light chain protein predicts greater brain-age gap, cognition, and cardiovascular risk in people with HIV.
  19. The two autophagy-related proteins 8a and 8b play distinct physiological roles in Drosophila.
  20. Identification of compounds that cause axonal dieback without cytotoxicity in dorsal root ganglia explants and intervertebral disc cells with potential to treat pain via denervation.
  21. Loss of tumor suppressor TMEM127 drives RET-mediated transformation through disrupted membrane dynamics.
  22. Frontotemporal dementia: from genetics to therapeutic approaches.
  1. Neurobiol Dis. 2024 Apr 25. pii: S0969-9961(24)00115-3. [Epub ahead of print]196 106516
    CK1δ/ε kinases regulate TDP-43 phosphorylation and are therapeutic targets for ALS-related TDP-43 hyperphosphorylation.
    Vivian I Ko, Kailee Ong, Don W Cleveland, Haiyang Yu, John M Ravits.
      Hyperphosphorylated TAR DNA-binding protein 43 (TDP-43) aggregates in the cytoplasm of neurons is the neuropathological hallmark of amyotrophic lateral sclerosis (ALS) and a group of neurodegenerative diseases collectively referred to as TDP-43 proteinopathies that includes frontotemporal dementia, Alzheimer's disease, and limbic onset age-related TDP-43 encephalopathy. The mechanism of TDP-43 phosphorylation is poorly understood. Previously we reported casein kinase 1 epsilon gene (CSNK1E gene encoding CK1ε protein) as being tightly correlated with phosphorylated TDP-43 (pTDP-43) pathology. Here we pursued studies to investigate in cellular models and in vitro how CK1ε and CK1δ (a closely related family sub-member) mediate TDP-43 phosphorylation in disease. We first validated the binding interaction between TDP-43 and either CK1δ and CK1ε using kinase activity assays and predictive bioinformatic database. We utilized novel inducible cellular models that generated translocated phosphorylated TDP-43 (pTDP-43) and cytoplasmic aggregation. Reducing CK1 kinase activity with siRNA or small molecule chemical inhibitors resulted in significant reduction of pTDP-43, in both soluble and insoluble protein fractions. We also established CK1δ and CK1ε are the primary kinases that phosphorylate TDP-43 compared to CK2α, CDC7, ERK1/2, p38α/MAPK14, and TTBK1, other identified kinases that have been implicated in TDP-43 phosphorylation. Throughout our studies, we were careful to examine both the soluble and insoluble TDP-43 protein fractions, the critical protein fractions related to protein aggregation diseases. These results identify CK1s as critical kinases involved in TDP-43 hyperphosphorylation and aggregation in cellular models and in vitro, and in turn are potential therapeutic targets by way of CK1δ/ε inhibitors.
    Keywords:  Amyotrophic lateral sclerosis; Casein kinase 1 delta; Casein kinase 1 epsilon; Phosphorylation; TAR DNA-binding protein (TDP-43); TDP-43 proteinopathies
    DOI:  https://doi.org/10.1016/j.nbd.2024.106516
  2. Nat Commun. 2024 May 02. 15(1): 3606
    Disease related changes in ATAC-seq of iPSC-derived motor neuron lines from ALS patients and controls.
    Answer ALS Consortium
      Amyotrophic Lateral Sclerosis (ALS), like many other neurodegenerative diseases, is highly heritable, but with only a small fraction of cases explained by monogenic disease alleles. To better understand sporadic ALS, we report epigenomic profiles, as measured by ATAC-seq, of motor neuron cultures derived from a diverse group of 380 ALS patients and 80 healthy controls. We find that chromatin accessibility is heavily influenced by sex, the iPSC cell type of origin, ancestry, and the inherent variance arising from sequencing. Once these covariates are corrected for, we are able to identify ALS-specific signals in the data. Additionally, we find that the ATAC-seq data is able to predict ALS disease progression rates with similar accuracy to methods based on biomarkers and clinical status. These results suggest that iPSC-derived motor neurons recapitulate important disease-relevant epigenomic changes.
    DOI:  https://doi.org/10.1038/s41467-024-47758-8
  3. Neurol Sci. 2024 Apr 27.
    Skeletal muscle dysfunction in amyotrophic lateral sclerosis: a mitochondrial perspective and therapeutic approaches.
    Gokhan Burcin Kubat, Pasquale Picone.
      Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neuromuscular disease that results in the loss of motor neurons and severe skeletal muscle atrophy. The etiology of ALS is linked to skeletal muscle, which can activate a retrograde signaling cascade that destroys motor neurons. This is why satellite cells and mitochondria play a crucial role in the health and performance of skeletal muscles. This review presents current knowledge on the involvement of mitochondrial dysfunction, skeletal muscle atrophy, muscle satellite cells, and neuromuscular junction (NMJ) in ALS. It also discusses current therapeutic strategies, including exercise, drugs, stem cells, gene therapy, and the prospective use of mitochondrial transplantation as a viable therapeutic strategy.
    Keywords:  Amyotrophic lateral sclerosis; Mitochondria; Mitochondrial transplantation; Skeletal muscle dysfunction
    DOI:  https://doi.org/10.1007/s10072-024-07508-6
  4. Hum Mol Genet. 2024 Apr 27. pii: ddae072. [Epub ahead of print]
    An integrative miRNA-mRNA expression analysis identifies miRNA signatures associated with SOD1 and TARDBP patient-derived motor neurons.
    Banaja P Dash, Axel Freischmidt, Jochen H Weishaupt, Andreas Hermann.
      MicroRNAs (miRNAs) are a subset of small non-coding single-stranded RNA molecules involved in the regulation of post-transcriptional gene expression of a variety of transcript targets. Therefore altered miRNA expression may result in the dysregulation of key genes and biological pathways that has been reported with the onset and progression of neurodegenerative diseases, such as Amyotrophic lateral sclerosis (ALS). ALS is marked by a progressive degeneration of motor neurons (MNs) present in the spinal cord, brain stem and motor cortex. Although the pathomechanism underlying molecular interactions of ALS remains poorly understood, alterations in RNA metabolism, including dysregulation of miRNA expression in familial as well as sporadic forms are still scarcely studied. In this study, we performed combined transcriptomic data and miRNA profiling in MN samples of the same samples of iPSC-derived MNs from SOD1- and TARDBP (TDP-43 protein)-mutant-ALS patients and healthy controls. We report a global upregulation of mature miRNAs, and suggest that differentially expressed (DE) miRNAs have a significant impact on mRNA-level in SOD1-, but not in TARDBP-linked ALS. Furthermore, in SOD1-ALS we identified dysregulated miRNAs such as miR-124-3p, miR-19b-3p and miR-218 and their potential targets previously implicated in important functional process and pathogenic pathways underlying ALS. These miRNAs may play key roles in the neuronal development and cell survival related functions in SOD1-ALS. Altogether, we provide evidence of miRNA regulated genes expression mainly in SOD1 rather than TDP43-ALS.
    Keywords:  RNA sequencing; amyotrophic lateral sclerosis; differentially expressed; human induced pluripotent stem cells; microRNA; motor neurons
    DOI:  https://doi.org/10.1093/hmg/ddae072
  5. J Neurosci. 2024 May 01. pii: e2148232024. [Epub ahead of print]
    Mutation of the ALS/FTD-associated RNA-binding protein FUS affects axonal development.
    Francesca W van Tartwijk, Lucia C S Wunderlich, Ioanna Mela, Stanislaw Makarchuk, Maximilian A H Jakobs, Seema Qamar, Kristian Franze, Gabriele S Kaminski Schierle, Peter H St George-Hyslop, Julie Qiaojin Lin, Christine E Holt, Clemens F Kaminski.
      Aberrant condensation and localisation of the RNA-binding protein (RBP) fused in sarcoma (FUS) occur in variants of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Changes in RBP function are commonly associated with changes in axonal cytoskeletal organisation and branching in neurodevelopmental disorders. Here, we asked whether branching defects also occur in vivo in a model of FUS-associated disease. We use two reported Xenopus models of ALS/FTD (of either sex), the ALS-associated mutant FUS(P525L) and a mimic of hypomethylated FUS, FUS(16R). Both mutants strongly reduced axonal complexity in vivo. We also observed an axon looping defect for FUS(P525L) in the target area, which presumably arises due to errors in stop cue signalling. To assess whether loss of axon complexity also had a cue-independent component, we assessed axonal cytoskeletal integrity in vitro Using a novel combination of fluorescence and atomic force microscopy, we found that mutant FUS reduced actin density in the growth cone, altering its mechanical properties. Therefore, FUS mutants may induce defects during early axonal development.Significance statement This study demonstrates that mutation of the ALS/FTD (amyotrophic lateral sclerosis/frontotemporal dementia)-associated RNA-binding protein Fused in Sarcoma (FUS) can result in changes in axonal development. These changes occur both axon-autonomously in cytoskeletal organisation during axon extension and context-dependently during axonal branching. This indicates pre-symptomatic, developmental changes in axonal organisation may occur in familial disease variants.
    DOI:  https://doi.org/10.1523/JNEUROSCI.2148-23.2024
  6. EMBO Rep. 2024 Apr 29.
    Glucose hypometabolism prompts RAN translation and exacerbates C9orf72-related ALS/FTD phenotypes.
    Andrew T Nelson, Maria Elena Cicardi, Shashirekha S Markandaiah, John Ys Han, Nancy J Philp, Emily Welebob, Aaron R Haeusler, Piera Pasinelli, Giovanni Manfredi, Hibiki Kawamata, Davide Trotti.
      The most prevalent genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia is a (GGGGCC)n nucleotide repeat expansion (NRE) occurring in the first intron of the C9orf72 gene (C9). Brain glucose hypometabolism is consistently observed in C9-NRE carriers, even at pre-symptomatic stages, but its role in disease pathogenesis is unknown. Here, we show alterations in glucose metabolic pathways and ATP levels in the brains of asymptomatic C9-BAC mice. We find that, through activation of the GCN2 kinase, glucose hypometabolism drives the production of dipeptide repeat proteins (DPRs), impairs the survival of C9 patient-derived neurons, and triggers motor dysfunction in C9-BAC mice. We also show that one of the arginine-rich DPRs (PR) could directly contribute to glucose metabolism and metabolic stress by inhibiting glucose uptake in neurons. Our findings provide a potential mechanistic link between energy imbalances and C9-ALS/FTD pathogenesis and suggest a feedforward loop model with potential opportunities for therapeutic intervention.
    Keywords:  ALS; C9orf72; FTD; Glucose Hypometabolism; RAN Translation
    DOI:  https://doi.org/10.1038/s44319-024-00140-7
  7. PLoS One. 2024 ;19(4): e0302280
    Small peptide CSF fingerprint of amyotrophic lateral sclerosis.
    Rea Lumi, Susanne Petri, Justyna Siwy, Agnieszka Latosinska, Julia Raad, Petra Zürbig, Thomas Skripuletz, Harald Mischak, Joachim Beige.
      BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by abnormal protein aggregation in the motor neurons. Present and earlier proteomic studies to characterize peptides in cerebrospinal fluid (CSF) associated with motoneuron pathology did not target low molecular weight proteins and peptides. We hypothesized that specific changes in CSF peptides or low molecular weight proteins are significantly altered in ALS, and that these changes may support deciphering molecular pathophysiology and even guide approaches towards therapeutic interventions.METHODS: Cerebrospinal fluid (CSF) from 50 ALS patients and 50 non-ALS controls was collected, centrifuged immediately after collection, aliquoted into polypropylene test tubes, frozen within 30-40 min after the puncture, and stored at -80°C until use. Peptides were sequenced using capillary electrophoresis or liquid chromatography/mass spectrometry (CE-MS/MS or LC-MS/MS).
    FINDINGS: In the CSF of 50 patients and 50 non-ALS controls 33 peptides were found, of which 14 could be sequenced using a non-lytic single-pot proteomic detection method, CE/MS. ALS deregulated peptides vs. controls included Integral membrane protein 2B, Neurosecretory protein VGF, Osteopontin, Neuroendocrine protein 7B2 (Secretogranin-V), EGF-containing fibulin-like extracellular matrix protein 1, Xylosyltransferase 1 XT-1, Chromogranin-A, Superoxide dismutase SOD-1, Secretogranin-1 (Chromogranin B), NR2F2 Nuclear Receptor Subfamily 2 Group F Member 2 and Collagen alpha-1(VII) chain.
    INTERPRETATION: Most striking deregulations in CSF from ALS patients were found in VGF, Osteopontin, SOD-1 and EFEMP1 peptides. No associations of disease severity, duration and region of onset with sequenced peptides were found.
    DOI:  https://doi.org/10.1371/journal.pone.0302280
  8. Stem Cell Res Ther. 2024 May 03. 15(1): 132
    Monocytes prevent apoptosis of iPSCs and promote differentiation of kidney organoids.
    Ekaterina Pecksen, Sergey Tkachuk, Cristoph Schröder, Marc Vives Enrich, Anindita Neog, Cory P Johnson, Niko Lachmann, Hermann Haller, Yulia Kiyan.
      BACKGROUND: Induced pluripotent stem cells (iPSCs)-derived kidney organoids are a promising model for studying disease mechanisms and renal development. Despite several protocols having been developed, further improvements are needed to overcome existing limitations and enable a wider application of this model. One of the approaches to improve the differentiation of renal organoids in vitro is to include in the system cell types important for kidney organogenesis in vivo, such as macrophages. Another approach could be to improve cell survival. Mesodermal lineage differentiation is the common initial step of the reported protocols. The glycogen synthase kinase-3 (GSK-3) activity inhibitor, CHIR99021 (CHIR), is applied to induce mesodermal differentiation. It has been reported that CHIR simultaneously induces iPSCs apoptosis that can compromise cell differentiation. We thought to interfere with CHIR-induced apoptosis of iPSCs using rapamycin.METHODS: Differentiation of kidney organoids from human iPSCs was performed. Cell survival and autophagy were analyzed using Cell counting kit 8 (CCK8) kit and Autophagy detection kit. Cells were treated with rapamycin or co-cultured with human monocytes isolated from peripheral blood or iPSCs-macrophages using a transwell co-culture system. Monocyte-derived extracellular vesicles (EVs) were isolated using polyethylene glycol precipitation. Expression of apoptotic markers cleaved Caspase 3, Poly [ADP-ribose] polymerase 1 (PARP-1) and markers of differentiation T-Box Transcription Factor 6 (TBX6), odd-skipped related 1 (OSR1), Nephrin, E-Cadherin, Paired box gene 2 (Pax2) and GATA Binding Protein 3 (Gata3) was assessed by RT-PCR and western blotting. Organoids were imaged by 3D-confocal microscopy.
    RESULTS: We observed that CHIR induced apoptosis of iPSCs during the initial stage of renal organoid differentiation. Underlying mechanisms implied the accumulation of reactive oxygen species and decreased autophagy. Activation of autophagy by rapamacin and by an indirect co-culture of differentiating iPSCs with iPSCs-macrophages and human peripheral blood monocytes prevented apoptosis induced by CHIR. Furthermore, monocytes (but not rapamycin) strongly promoted expression of renal differentiation markers and organoids development via released extracellular vesicles.
    CONCLUSION: Our data suggest that co-culturing of iPSCs with human monocytes strongly improves differentiation of kidney organoids. An underlying mechanism of monocytic action implies, but not limited to, an increased autophagy in CHIR-treated iPSCs. Our findings enhance the utility of kidney organoid models.
    Keywords:  Apoptosis; Autophagy; Kidney organoids; Monocytes; iPSCs; iPSCs-macrophages
    DOI:  https://doi.org/10.1186/s13287-024-03739-8
  9. J Neurosci. 2024 May 01. pii: e2424232024. [Epub ahead of print]
    Context-specific stress causes compartmentalized SARM1 activation and local degeneration in cortical neurons.
    Flora I Hinz, Carmela Louise M Villegas, Jasmine T Roberts, Heming Yao, Shreya Gaddam, Anton Delwig, Samantha A Green, Craig Fredrickson, Max Adrian, Raymond R Asuncion, Tommy K Cheung, Margaret Hayne, David H Hackos, Christopher M Rose, David Richmond, Casper C Hoogenraad.
      SARM1 is an inducible NADase that localizes to mitochondria throughout neurons and senses metabolic changes that occur after injury. Minimal proteomic changes are observed upon either SARM1 depletion or activation, suggesting that SARM1 does not exert broad effects on neuronal protein homeostasis. However, whether SARM1 activation occurs throughout the neuron in response to injury and cell stress remains largely unknown. Using a semi-automated imaging pipeline and a custom-built deep learning scoring algorithm, we studied degeneration in both mixed sex mouse primary cortical neurons and male human iPSC derived cortical neurons in response to a number of different stressors. We show that SARM1 activation is differentially restricted to specific neuronal compartments depending on the stressor. Cortical neurons undergo SARM1-dependent axon degeneration after mechanical transection and SARM1 activation is limited to the axonal compartment distal of the injury site. However, global SARM1 activation following vacor treatment causes both cell body and axon degeneration. Context-specific stressors, such as microtubule dysfunction and mitochondrial stress, induce axonal SARM1 activation leading to SARM1-dependent axon degeneration and SARM1-independent cell body death. Our data reveal that compartment-specific SARM1-mediated death signaling is dependent on the type of injury and cellular stressor.Significance Statement SARM1 is an important regulator of active axon degeneration after injury in the peripheral nervous system. Here we show that SARM1 can also be activated by a number of different cellular stressors in cortical neurons of the central nervous system. Loss or activation of SARM1 does not cause large scale changes in global protein homeostasis. However, context-dependent SARM1 activation is localized to specific neuronal compartments and results in localized degeneration of axons. Understanding which cell stress pathways are responsible for driving degeneration of distinct neuronal compartments under what cellular stress conditions and in which neuronal subtypes, will inform development of neurodegenerative disease therapeutics.
    DOI:  https://doi.org/10.1523/JNEUROSCI.2424-23.2024
  10. Front Endocrinol (Lausanne). 2024 ;15 1361289
    Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions.
    Wenhan Ju, Yuewen Zhao, Yi Yu, Shuai Zhao, Shan Xiang, Fang Lian.
      Mitochondria plays an essential role in regulating cellular metabolic homeostasis, proliferation/differentiation, and cell death. Mitochondrial dysfunction is implicated in many age-related pathologies. Evidence supports that the dysfunction of mitochondria and the decline of mitochondrial DNA copy number negatively affect ovarian aging. However, the mechanism of ovarian aging is still unclear. Treatment methods, including antioxidant applications, mitochondrial transplantation, emerging biomaterials, and advanced technologies, are being used to improve mitochondrial function and restore oocyte quality. This article reviews key evidence and research updates on mitochondrial damage in the pathogenesis of ovarian aging, emphasizing that mitochondrial damage may accelerate and lead to cellular senescence and ovarian aging, as well as exploring potential methods for using mitochondrial mechanisms to slow down aging and improve oocyte quality.
    Keywords:  aging; fertility preservation; mechanism; mitochondria; oocyte
    DOI:  https://doi.org/10.3389/fendo.2024.1361289
  11. Methods Mol Biol. 2024 ;2803 35-48
    Generation of 3D-Multicellular Human iPSC-Heart Organoids for the Noninvasive Assessment of Cardiac Fibrosis.
    Antonio Lucena-Cacace, Yu Tian, Yoshinori Yoshida.
      The lack of a precise noninvasive, clinical evaluation method for cardiac fibrosis hinders the development of successful treatments that can effectively work in physiological settings, where tissues and organs are interconnected and moderating drug responses. To address this challenge and advance personalized medicine, researchers have turned to human-induced pluripotent stem (iPS) cells, which can be differentiated to resemble the human heart in terms of structure, function and cellular composition. In this chapter, we present an assay protocol that uses these iPS cells to generate heart organoids for the in vitro evaluation of cardiac fibrosis. By establishing this biological platform, we pave the way for conducting phenotype evaluation and treatment screening in a multiscale approach, aiming to discover effective interventions for the treatment of cardiac fibrosis.
    Keywords:  Cardiac fibrosis; Cardiac organoid; Differentiation; Fibroblasts; Heart organoid; Reactive fibrosis; Replacement fibrosis; TGFβ; hiPSCs
    DOI:  https://doi.org/10.1007/978-1-0716-3846-0_3
  12. Cell Death Dis. 2024 Apr 29. 15(4): 302
    Mature neurons from iPSCs unveil neurodegeneration-related pathways in mucopolysaccharidosis type II: GSK-3β inhibition for therapeutic potential.
    Tzu-Yu Chen, Shuan-Pei Lin, De-Fong Huang, Hsien-Sung Huang, Feng-Chiao Tsai, Li-Jen Lee, Hsiang-Yu Lin, Hsiang-Po Huang.
      Mucopolysaccharidosis (MPS) type II is caused by a deficiency of iduronate-2-sulfatase and is characterized by the accumulation of glycosaminoglycans (GAGs). Without effective therapy, the severe form of MPS II causes progressive neurodegeneration and death. This study generated multiple clones of induced pluripotent stem cells (iPSCs) and their isogenic controls (ISO) from four patients with MPS II neurodegeneration. MPS II-iPSCs were successfully differentiated into cortical neurons with characteristic biochemical and cellular phenotypes, including axonal beadings positive for phosphorylated tau, and unique electrophysiological abnormalities, which were mostly rescued in ISO-iPSC-derived neurons. RNA sequencing analysis uncovered dysregulation in three major signaling pathways, including Wnt/β-catenin, p38 MAP kinase, and calcium pathways, in mature MPS II neurons. Further mechanistic characterization indicated that the dysregulation in calcium signaling led to an elevated intracellular calcium level, which might be linked to compromised survival of neurons. Based on these dysregulated pathways, several related chemicals and drugs were tested using this mature MPS II neuron-based platform and a small-molecule glycogen synthase kinase-3β inhibitor was found to significantly rescue neuronal survival, neurite morphology, and electrophysiological abnormalities in MPS II neurons. Our results underscore that the MPS II-iPSC-based platform significantly contributes to unraveling the mechanisms underlying the degeneration and death of MPS II neurons and assessing potential drug candidates. Furthermore, the study revealed that targeting the specific dysregulation of signaling pathways downstream of GAG accumulation in MPS II neurons with a well-characterized drug could potentially ameliorate neuronal degeneration.
    DOI:  https://doi.org/10.1038/s41419-024-06692-9
  13. Nucleus. 2024 Dec;15(1): 2349085
    Nuclear and degradative functions of the ESCRT-III pathway: implications for neurodegenerative disease.
    Olivia Keeley, Alyssa N Coyne.
      The ESCRT machinery plays a pivotal role in membrane-remodeling events across multiple cellular processes including nuclear envelope repair and reformation, nuclear pore complex surveillance, endolysosomal trafficking, and neuronal pruning. Alterations in ESCRT-III functionality have been associated with neurodegenerative diseases including Frontotemporal Dementia (FTD), Amyotrophic Lateral Sclerosis (ALS), and Alzheimer's Disease (AD). In addition, mutations in specific ESCRT-III proteins have been identified in FTD/ALS. Thus, understanding how disruptions in the fundamental functions of this pathway and its individual protein components in the human central nervous system (CNS) may offer valuable insights into mechanisms underlying neurodegenerative disease pathogenesis and identification of potential therapeutic targets. In this review, we discuss ESCRT components, dynamics, and functions, with a focus on the ESCRT-III pathway. In addition, we explore the implications of altered ESCRT-III function for neurodegeneration with a primary emphasis on nuclear surveillance and endolysosomal trafficking within the CNS.
    Keywords:  Amyotrophic lateral sclerosis; ESCRT-III pathway; endolysosomal trafficking; frontotemporal dementia; neurodegenerative diseases; nuclear pore complex; nuclear surveillance; protein degradation
    DOI:  https://doi.org/10.1080/19491034.2024.2349085
  14. Mol Cell. 2024 May 02. pii: S1097-2765(24)00280-6. [Epub ahead of print]84(9): 1633-1634
    eIF4G as a switch for heat shock mRNA translation.
    Yi Liu, Peiguo Yang.
      The heat shock response is crucial for cell survival. In this issue of Molecular Cell, Desroches Altamirano et al.1 demonstrate that a temperature-induced conformational change in the translation initiation factor eIF4G is a key mechanism regulating translation during the heat shock response.
    DOI:  https://doi.org/10.1016/j.molcel.2024.04.002
  15. Front Mol Biosci. 2024 ;11 1370933
    Proteomic analysis reveals a potential role for extracellular vesicles within the erythroblastic island niche.
    Telma Ventura, Antonella Fidanza, Marieangela C Wilson, Daniel C J Ferguson, Phillip A Lewis, Alisha May, Helen Taylor, Michael P Rimmer, Christopher D Gregory, Jan Frayne, Lesley M Forrester.
      Introduction: Erythroblastic island (EBI) macrophages play an essential role in the production and maturation of the vast numbers of red blood cells (RBCs) that are produced throughout life. Their location within the bone marrow makes it difficult to study the cellular and molecular interactions associated with their action so we have used an in vitro model of the EBI niche using macrophages derived from human induced pluripotent stem cells (hiPSCs). We previously demonstrated that the activation of the transcription factor KLF1 enhanced the activity of hiPSC-derived EBI macrophages. Methods: To elucidate the mechanisms associated with EBI-like activity we carried out a quantitative proteomic analysis and assessed the role of extracellular vesicles using Nanosight Tracking analyses and media filtration. Results and Discussion: Gene ontology analysis showed that many of the proteins upregulated by KLF1 were protein-binding factors, some of which were associated with the cell membrane or extracellular vesicles We demonstrated that filtration of macrophage-conditioned media resulted in a reduction in the supportive effects on erythroid cell viability and maturation implying a role for extracellular vesicles but this was not KLF1 dependent. Pathway analyses of the proteomic data revealed that proteins upregulated by KLF1 were associated with the citric acid cycle, pyruvate metabolism and ATP synthesis indicating that KLF1-activated macrophages had a metabolic profile comparable to a pro-reparative phenotype. This study has generated a proteomic dataset that could provide new insights into the role of macrophages within the EBI niche and has indicated a potential role for extracellular vesicles in the differentiation and maturation of RBCs in vitro. Further research will aid in the production of RBCs in vitro for use in disease modelling and cell therapy.
    Keywords:  KLF1; erythroblastic island macrophage; extracellular vesicles; induced pluripotent stem cells; proteomics
    DOI:  https://doi.org/10.3389/fmolb.2024.1370933
  16. Proc Natl Acad Sci U S A. 2024 May 07. 121(19): e2313590121
    Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle.
    Kai-Yu Huang, Gaurav Upadhyay, Yujin Ahn, Masayoshoi Sakakura, Gelson J Pagan-Diaz, Younghak Cho, Amanda C Weiss, Chen Huang, Jennifer W Mitchell, Jiahui Li, Yanqi Tan, Yu-Heng Deng, Austin Ellis-Mohr, Zhi Dou, Xiaotain Zhang, Sehong Kang, Qian Chen, Jonathan V Sweedler, Sung Gap Im, Rashid Bashir, Hee Jung Chung, Gabriel Popescu, Martha U Gillette, Mattia Gazzola, Hyunjoon Kong.
      Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.
    Keywords:  exosome; innervation; myokine; neuromuscular junction; skeletal muscle
    DOI:  https://doi.org/10.1073/pnas.2313590121
  17. Biosci Rep. 2024 May 03. pii: BSR20240562. [Epub ahead of print]
    sFlt-1 Impairs Neurite Growth and Neuronal Differentiation in SH-SY5Y Cells and Human Neurons.
    Aaron Barron, Lauren Barrett, Jetro Tuulari, Linnea Karlsson, Hasse Karlsson, Cathal M McCarthy, Gerard W O'Keeffe.
      Pre-eclampsia (PE) is a hypertensive disorder of pregnancy which is associated with increased risk of neurodevelopmental disorders in exposed offspring. The pathophysiological mechanisms mediating this relationship are currently unknown, and one potential candidate is the anti-angiogenic factor soluble Fms-like tyrosine kinase 1 (sFlt-1), which is highly elevated in PE. While sFlt-1 can impair angiogenesis via inhibition of VEGFA signalling, it is unclear whether it can directly affect neuronal development independently of its effects on the vasculature. To test this hypothesis, the current study differentiated the human neural progenitor cell (NPC) line ReNcell® VM into a mixed culture of mature neurons and glia, and exposed them to sFlt-1 during development. Outcomes measured were neurite growth, cytotoxicity, mRNA expression of nestin, MBP, GFAP, and βIII-tubulin, and neurosphere differentiation. sFlt-1 induced a significant reduction in neurite growth and this effect was timing- and dose-dependent up to 100 ng/mL, with no effect on cytotoxicity. sFlt-1 (100 ng/mL) also reduced βIII-tubulin mRNA and neuronal differentiation of neurospheres. Undifferentiated NPCs and mature neurons/glia expressed VEGFA and VEGFR-2, required for endogenous autocrine and paracrine VEGFA signalling, while sFlt-1 treatment prevented the neurogenic effects of exogenous VEGFA. Overall, these data provide the first experimental evidence for a direct effect of sFlt-1 on neurite growth and neuronal differentiation in human neurons through inhibition of VEGFA signalling, clarifying our understanding of the potential role of sFlt-1 as a mechanism by which PE can affect neuronal development.
    Keywords:  Neuron; Pre-eclampsia; axon; differentiation; growth; sFLT-1
    DOI:  https://doi.org/10.1042/BSR20240562
  18. AIDS. 2024 Jun 01. 38(7): 1081-1083
    Plasma neurofilament light chain protein predicts greater brain-age gap, cognition, and cardiovascular risk in people with HIV.
    David E Vance, Bruce James Brew.
      
    DOI:  https://doi.org/10.1097/QAD.0000000000003880
  19. Genomics. 2024 May 01. pii: S0888-7543(24)00074-0. [Epub ahead of print] 110853
    The two autophagy-related proteins 8a and 8b play distinct physiological roles in Drosophila.
    Yuchen Xu, Wei Liu, Zhaolin Sun, Yurun Yu, Tianhao Yang, Xirui Lu, Guiqiang Zhang, Jianwei Jiao, Xiuying Duan.
      Atg8 family proteins play crucial roles in autophagy to maintain cellular homeostasis. However, the physiological roles of Atg8 family proteins have not been systematically determined. In this study, we generated Atg8a and Atg8b (homologs of Atg8 in Drosophila melanogaster) knockout flies. We found that the loss of Atg8a affected autophagy and resulted in partial lethality, abnormal wings, decreased lifespan, and decreased climbing ability in flies. Furthermore, the loss of Atg8a resulted in reduced muscle integrity and the progressive degeneration of the neuron system. We also found that the phosphorylation at Ser88 of Atg8a is important for autophagy and neuronal integrity. The loss of Atg8b did not affect autophagy but induced male sterility in flies. Here, we take full advantage of the fly system to elucidate the physiological function of Atg8a and Atg8b in Drosophila.
    Keywords:  Atg8; Autophagy; Developmental defects; Drosophila; Male sterility; Neurodegeneration
    DOI:  https://doi.org/10.1016/j.ygeno.2024.110853
  20. PLoS One. 2024 ;19(5): e0300254
    Identification of compounds that cause axonal dieback without cytotoxicity in dorsal root ganglia explants and intervertebral disc cells with potential to treat pain via denervation.
    Fei San Lee, Uyen N Nguyen, Eliza J Munns, Rebecca A Wachs.
      Low back pain, knee osteoarthritis, and cancer patients suffer from chronic pain. Aberrant nerve growth into intervertebral disc, knee, and tumors, are common pathologies that lead to these chronic pain conditions. Axonal dieback induced by capsaicin (Caps) denervation has been FDA-approved to treat painful neuropathies and knee osteoarthritis but with short-term efficacy and discomfort. Herein, we propose to evaluate pyridoxine (Pyr), vincristine sulfate (Vcr) and ionomycin (Imy) as axonal dieback compounds for denervation with potential to alleviate pain. Previous literature suggests Pyr, Vcr, and Imy can cause undesired axonal degeneration, but no previous work has evaluated axonal dieback and cytotoxicity on adult rat dorsal root ganglia (DRG) explants. Thus, we performed axonal dieback screening using adult rat DRG explants in vitro with Caps as a positive control and assessed cytotoxicity. Imy inhibited axonal outgrowth and slowed axonal dieback, while Pyr and Vcr at high concentrations produced significant reduction in axon length and robust axonal dieback within three days. DRGs treated with Caps, Vcr, or Imy had increased DRG cytotoxicity compared to matched controls, but overall cytotoxicity was minimal and at least 88% lower compared to lysed DRGs. Pyr did not lead to any DRG cytotoxicity. Further, neither Pyr nor Vcr triggered intervertebral disc cell death or affected cellular metabolic activity after three days of incubation in vitro. Overall, our findings suggest Pyr and Vcr are not toxic to DRGs and intervertebral disc cells, and there is potential for repurposing these compounds for axonal dieback compounds to cause local denervation and alleviate pain.
    DOI:  https://doi.org/10.1371/journal.pone.0300254
  21. Elife. 2024 Apr 30. pii: RP89100. [Epub ahead of print]12
    Loss of tumor suppressor TMEM127 drives RET-mediated transformation through disrupted membrane dynamics.
    Timothy J Walker, Eduardo Reyes-Alvarez, Brandy D Hyndman, Michael G Sugiyama, Larissa C B Oliveira, Aisha N Rekab, Mathieu J F Crupi, Rebecca Cabral-Dias, Qianjin Guo, Patricia L M Dahia, Douglas S Richardson, Costin N Antonescu, Lois M Mulligan.
      Internalization from the cell membrane and endosomal trafficking of receptor tyrosine kinases (RTKs) are important regulators of signaling in normal cells that can frequently be disrupted in cancer. The adrenal tumor pheochromocytoma (PCC) can be caused by activating mutations of the rearranged during transfection (RET) receptor tyrosine kinase, or inactivation of TMEM127, a transmembrane tumor suppressor implicated in trafficking of endosomal cargos. However, the role of aberrant receptor trafficking in PCC is not well understood. Here, we show that loss of TMEM127 causes wildtype RET protein accumulation on the cell surface, where increased receptor density facilitates constitutive ligand-independent activity and downstream signaling, driving cell proliferation. Loss of TMEM127 altered normal cell membrane organization and recruitment and stabilization of membrane protein complexes, impaired assembly, and maturation of clathrin-coated pits, and reduced internalization and degradation of cell surface RET. In addition to RTKs, TMEM127 depletion also promoted surface accumulation of several other transmembrane proteins, suggesting it may cause global defects in surface protein activity and function. Together, our data identify TMEM127 as an important determinant of membrane organization including membrane protein diffusability and protein complex assembly and provide a novel paradigm for oncogenesis in PCC where altered membrane dynamics promotes cell surface accumulation and constitutive activity of growth factor receptors to drive aberrant signaling and promote transformation.
    Keywords:  RET; TMEM127; cancer biology; cell biology; clathrin-mediated endocytosis; human; membrane dynamics; pheochromocytoma
    DOI:  https://doi.org/10.7554/eLife.89100
  22. Expert Opin Investig Drugs. 2024 Apr 30.
    Frontotemporal dementia: from genetics to therapeutic approaches.
    Francesca R Buccellato, Marianna D'Anca, Gianluca Martino Tartaglia, Massimo Del Fabbro, Daniela Galimberti.
      INTRODUCTION: Frontotemporal dementia (FTD) includes a group of neurodegenerative diseases characterized clinically by behavioral disturbances and by neurodegeneration of brain anterior temporal and frontal lobes, leading to atrophy. Apart from symptomatic treatments, there is, at present, no disease-modifying cure for FTD.AREAS COVERED: Three main mutations are known as causes of familial FTD, and large consortia have studied carriers of mutations, also in preclinical Phases. As genetic cases are the only ones in which the pathology can be predicted in life, compounds developed so far are directed toward specific proteins or mutations. Herein, recently approved clinical trials will be summarized, including molecules, mechanisms of action and pharmacological testing.
    EXPERT OPINION: These studies are paving the way for the future. They will clarify whether single mutations should be addressed rather than common proteins depositing in the brain to move from genetic to sporadic FTD.
    Keywords:  Chromosome 9 open reading frame 72 (C9orf72); Frontotemporal dementia (FTD); Frontotemporal lobar degeneration (FTLD); Microtubule associated protein tau (MAPT); Progranulin (GRN); TAR DNA-binding protein 43 (TDP-43)
    DOI:  https://doi.org/10.1080/13543784.2024.2349286
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