Primary Motor Neurons Research Articles

Myelinated axons fail to develop properly in a genetically authentic mouse model of Charcot-Marie-Tooth disease type 2E

We have analyzed a mouse model of Charcot-Marie-Tooth disease 2E (CMT2E) harboring a heterozygous p.Asn98Ser (p.N98S) Nefl mutation, whose human counterpart results in a severe, early-onset neuropathy. Behavioral, electrophysiological, and pathological analyses were done on separate cohorts of NeflN98S/+ mutant mice and their wild type Nefl+/+ littermates between 8 and 48 weeks of age. The motor performance of NeflN98S/+ mice, as evidenced by altered balance and gait measures, was impaired at every age examined (from 6 to 25 weeks of age). At all times examined, myelinated axons were smaller and contained markedly fewer neurofilaments in NeflN98S/+ mice, in all examined aspects of the PNS, from the nerve roots to the distal ends of the sciatic and caudal nerves. Similarly, the myelinated axons in the various tracts of the spinal cord and in the optic nerves were smaller and contained fewer neurofilaments in mutant mice. The myelinated axons in both the PNS and the CNS of mutant mice had relatively thicker myelin sheaths. The amplitude and the nerve conduction velocity of the caudal nerves were reduced in proportion with the diminished sizes of myelinated axons. Conspicuous aggregations of neurofilaments were only seen in primary sensory and motor neurons, and were largely confined to the cell bodies and proximal axons. There was evidence of axonal degeneration and regeneration of myelinated axons, mostly in distal nerves. In summary, the p.N98S mutation causes a profound reduction of neurofilaments in the myelinated axons of the PNS and CNS, resulting in substantially reduced axonal diameters, particularly of large myelinated axons, and distal axon loss in the PNS.

Investigation of Islet2a function in zebrafish embryos: Mutants and morphants differ in morphologic phenotypes and gene expression.

Zebrafish primary motor neurons differ from each other with respect to morphology, muscle targets and electrophysiological properties. For example, CaP has 2-3-fold larger densities of both inward and outward currents than do other motor neurons. We tested whether the transcription factor Islet2a, uniquely expressed in CaP, but not other primary motor neurons, plays a role in specifying its stereotypic electrophysiological properties. We used both TALEN-based gene editing and antisense morpholino approaches to disrupt Islet2a function. Our electrophysiology results do not support a specific role for Islet2a in determining CaP’s unique electrical properties. However, we also found that the morphological phenotypes of CaP and a later-born motor neuron differed between islet2a mutants and morphants. Using microarrays, we tested whether the gene expression profiles of whole embryo morphants, mutants and controls also differed. Morphants had 174 and 201 genes that were differentially expressed compared to mutants and controls, respectively. Further, islet2a was identified as a differentially expressed gene. To examine how mutation of islet2a affected islet gene expression specifically in CaPs, we performed RNA in situ hybridization. We detected no obvious differences in expression of islet1, islet2a, or islet2b in CaPs of mutant versus sibling control embryos. However, immunolabeling studies revealed that an Islet protein persisted in CaPs of mutants, albeit at a reduced level compared to controls. While we cannot exclude requirement for some Islet protein, we conclude that differentiation of the CaP’s stereotypic large inward and outward currents does not have a specific requirement for Islet2a.

Inhibiting p38 MAPK alpha rescues axonal retrograde transport defects in a mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease caused by the degeneration of upper and lower motor neurons. Defects in axonal transport have been observed pre-symptomatically in the SOD1G93A mouse model of ALS, and have been proposed to play a role in motor neuron degeneration as well as in other pathologies of the nervous system, such as Alzheimer’s disease and hereditary neuropathies. In this study, we screen a library of small-molecule kinase inhibitors towards the identification of pharmacological enhancers of the axonal retrograde transport of signalling endosomes, which might be used to normalise the rate of this process in diseased neurons. Inhibitors of p38 mitogen-activated protein kinases (p38 MAPK) were identified in this screen and were found to correct deficits in axonal retrograde transport of signalling endosomes in cultured primary SOD1G93A motor neurons. In vitro knockdown experiments revealed that the alpha isoform of p38 MAPK (p38 MAPKα) was the sole isoform responsible for SOD1G93A-induced transport deficits. Furthermore, we found that acute treatment with p38 MAPKα inhibitors restored the physiological rate of axonal retrograde transport in vivo in early symptomatic SOD1G93A mice. Our findings demonstrate the pathogenic effect of p38 MAPKα on axonal retrograde transport and identify a potential therapeutic strategy for ALS.

TDP-43 regulation of stress granule dynamics in neurodegenerative disease-relevant cell types

Stress granules (SGs) are cytoplasmic foci that form in response to various external stimuli and are essential to cell survival following stress. SGs are studied in several diseases, including ALS and FTD, which involve the degeneration of motor and cortical neurons, respectively, and are now realized to be linked pathogenically by TDP-43, originally discovered as a component of ubiquitin-positive aggregates within patients’ neurons and some glial cells. So far, studies to undercover the role of TDP-43 in SGs have used primarily transformed cell lines, and thus rely on the extrapolation of the mechanisms to cell types affected in ALS/FTD, potentially masking cell specific effects. Here, we investigate SG dynamics in primary motor and cortical neurons as well as astrocytes. Our data suggest a cell and stress specificity and demonstrate a requirement for TDP-43 for efficient SG dynamics. In addition, based on our in vitro approach, our data suggest that aging may be an important modifier of SG dynamics which could have relevance to the initiation and/or progression of age-related neurodegenerative diseases.

Delivery of an anti-transthyretin Nanobody to the brain through intranasal administration reveals transthyretin expression and secretion by motor neurons.

Transthyretin (TTR) is a transport protein of retinol and thyroxine in serum and CSF, which is mainly secreted by liver and choroid plexus, and in smaller amounts in other cells throughout the body. The exact role of TTR and its specific expression in Central Nervous System (CNS) remains understudied. We investigated TTR expression and metabolism in CNS, through the intranasal and intracerebroventricular delivery of a specific anti‐TTR Nanobody to the brain, unveiling Nanobody pharmacokinetics to the CNS. In TTR deficient mice, we observed that anti‐TTR Nanobody was successfully distributed throughout all brain areas, and also reaching the spinal cord. In wild‐type mice, a similar distribution pattern was observed. However, in areas known to be rich in TTR, reduced levels of Nanobody were found, suggesting potential target‐mediated effects. Indeed, in wild‐type mice, the anti‐TTR Nanobody was specifically internalized in a receptor‐mediated process, by neuronal‐like cells, which were identified as motor neurons. Whereas in KO TTR mice Nanobody was internalized by all cells, for late lysosomal degradation. Moreover, we demonstrate that in vivo motor neurons also actively synthesize TTR. Finally, in vitro cultured primary motor neurons were also found to synthesize and secrete TTR into culture media. Thus, through a novel intranasal CNS distribution study with an anti‐TTR Nanobody, we disclose a new cell type capable of synthesizing TTR, which might be important for the understanding of the physiological role of TTR, as well as in pathological conditions where TTR levels are altered in CSF, such as amyotrophic lateral sclerosis.

TPC2-mediated Ca2+ signaling is required for the establishment of synchronized activity in developing zebrafish primary motor neurons

During the development of the early spinal circuitry in zebrafish, spontaneous Ca2+ transients in the primary motor neurons (PMNs) are reported to transform from being slow and uncorrelated, to being rapid, synchronized and patterned. In this study, we demonstrated that in intact zebrafish, Ca2+ release via two-pore channel type 2 (TPC2) from acidic stores/endolysosomes is required for the establishment of synchronized activity in the PMNs. Using the SAIGFF213A;UAS:GCaMP7a double-transgenic zebrafish line, Ca2+ transients were visualized in the caudal PMNs (CaPs). TPC2 inhibition via molecular, genetic or pharmacological means attenuated the CaP Ca2+ transients, and decreased the normal ipsilateral correlation and contralateral anti-correlation, indicating a disruption in normal spinal circuitry maturation. Furthermore, treatment with MS-222 resulted in a complete (but reversible) inhibition of the CaP Ca2+ transients, as well as a significant decrease in the concentration of the Ca2+ mobilizing messenger, nicotinic acid adenine diphosphate (NAADP) in whole embryo extract. Together, our new data suggest a novel function for NAADP/TPC2-mediated Ca2+ signaling in the development, coordination, and maturation of the spinal network in zebrafish embryos.

HnRNP R and its main interactor, the noncoding RNA 7SK, coregulate the axonal transcriptome of motoneurons

Disturbed RNA processing and subcellular transport contribute to the pathomechanisms of motoneuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy. RNA-binding proteins are involved in these processes, but the mechanisms by which they regulate the subcellular diversity of transcriptomes, particularly in axons, are not understood. Heterogeneous nuclear ribonucleoprotein R (hnRNP R) interacts with several proteins involved in motoneuron diseases. It is located in axons of developing motoneurons, and its depletion causes defects in axon growth. Here, we used individual nucleotide-resolution cross-linking and immunoprecipitation (iCLIP) to determine the RNA interactome of hnRNP R in motoneurons. We identified ∼3,500 RNA targets, predominantly with functions in synaptic transmission and axon guidance. Among the RNA targets identified by iCLIP, the noncoding RNA 7SK was the top interactor of hnRNP R. We detected 7SK in the nucleus and also in the cytosol of motoneurons. In axons, 7SK localized in close proximity to hnRNP R, and depletion of hnRNP R reduced axonal 7SK. Furthermore, suppression of 7SK led to defective axon growth that was accompanied by axonal transcriptome alterations similar to those caused by hnRNP R depletion. Using a series of 7SK-deletion mutants, we show that the function of 7SK in axon elongation depends on its interaction with hnRNP R but not with the PTEF-B complex involved in transcriptional regulation. These results propose a role for 7SK as an essential interactor of hnRNP R to regulate its function in axon maintenance.

흰쥐의 양지(TE4)에 대한 신경해부학적 연구

This research was practiced to comparative investigate the distribution of sensory and motor neuron linkaged with Yangji(TE4) by using neural-tracer technology. A total 16 S-D rats were used in the present research. After anesthesia, the rats received micro-injection of 6㎕ of cholera toxin B subunit(CTB) into the relation positions of the Yangji(TE4), in the human body for observing the distribution of the linkaged sensory neurons in dorsal root ganglia(DRGs) and motor neurons in the spinal cord(C3∼T4) and sympathetic ganglia. 3 days after the micro injection, the rats were anesthetized and transcardially perfused saline and 4% paraformaldehyde, followed by routine section of the DRGs, sympathetic chain ganglia(SCGs) and spinal cord. Marked neurons and nerve fibers were detected by immunohistochemical method and observed by light microscope. The marked neurons were recorded and counted. From this study the distribution of primary sensory and motor neurons linkaged with Yangji(TE4) were concluded as follows. Yangji(TE4) dominated by spinal segments of C5∼T1, C6∼T4, individually.

The Metabolic Disturbances of Motoneurons Exposed to Glutamate.

Glutamate-induced excitotoxicity is considered as one of the major pathophysiological factors of motoneuron death in amyotrophic lateral sclerosis and other motoneuron diseases. In order to expand our knowledge on mechanisms of glutamate-induced excitotoxicity, the present study proposes to determine the metabolic consequences of glutamate and astrocytes in primary enriched motoneuron culture. Using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS), we showed that the presence of astrocytes and glutamate profoundly modified the metabolic profile of motoneurons. Our study highlights for the first time that crosstalk between astrocytes and enriched motoneuron culture induced alterations in phenylalanine, tryptophan, purine, arginine, proline, aspartate, and glutamate metabolism in motoneurons. We observed that astrocytes modulate the sensitivity of motoneurons to glutamate, since metabolites altered by glutamate in motoneurons cultured alone were different (except 5-hydroxylysine) from those altered in co-cultured motoneurons. Our findings provide new insight into the metabolic alterations associated to astrocytes and glutamate in motoneurons and provide opportunities to identify novel therapeutic targets.

High content image analysis reveals function of miR-124 upstream of Vimentin in regulating motor neuron mitochondria

microRNAs (miRNAs) are critical for neuronal function and their dysregulation is repeatedly observed in neurodegenerative diseases. Here, we implemented high content image analysis for investigating the impact of several miRNAs in mouse primary motor neurons. This survey directed our attention to the neuron-specific miR-124, which controls axonal morphology. By performing next generation sequencing analysis and molecular studies, we characterized novel roles for miR-124 in control of mitochondria localization and function. We further demonstrated that the intermediate filament Vimentin is a key target of miR-124 in this system. Our data establishes a new pathway for control of mitochondria function in motor neurons, revealing the value of a neuron-specific miRNA gene as a mechanism for the re-shaping of otherwise ubiquitously-expressed intermediate filament network, upstream of mitochondria activity and cellular metabolism.

Als2 Silencing Affects the Expression of Two NF-κB Targeted Genes via UXT in Adult Mouse Primary Spinal Motor Neuron Culture

Als2 Silencing Affects the Expression of Two NF-κB Targeted Genes via UXT in Adult Mouse Primary Spinal Motor Neuron Culture

Evaluation Of Electrophysiological Changes In Primary Spinal Cord Neuronal Cultures Exposed To ALS-CSF Using Microelectrode Array.

Evaluation Of Electrophysiological Changes In Primary Spinal Cord Neuronal Cultures Exposed To ALS-CSF Using Microelectrode Array.

Comparative genomic analysis of embryonic, lineage-converted, and stem cell-derived motor neurons

Advances in stem cell science allow the production of different cell types in vitro either through the recapitulation of developmental processes, often termed 'directed differentiation', or the forced expression of lineage-specific transcription factors. Although cells produced by both approaches are increasingly used in translational applications, their quantitative similarity to their primary counterparts remains largely unresolved. To investigate the similarity between in vitro-derived and primary cell types, we harvested and purified mouse spinal motor neurons and compared them with motor neurons produced by transcription factor-mediated lineage conversion of fibroblasts or directed differentiation of pluripotent stem cells. To enable unbiased analysis of these motor neuron types and their cells of origin, we then subjected them to whole transcriptome and DNA methylome analysis by RNA sequencing (RNA-seq) and reduced representation bisulfite sequencing (RRBS). Despite major differences in methodology, lineage conversion and directed differentiation both produce cells that closely approximate the primary motor neuron state. However, we identify differences in Fas signaling, the Hox code and synaptic gene expression between lineage-converted and directed differentiation motor neurons that affect their utility in translational studies.

Knockdown of Laminin gamma-3 (Lamc3) impairs motoneuron guidance in the zebrafish embryo

Background: Previous work in the zebrafish embryo has shown that laminin γ-3 ( lamc3) is enriched in endothelial cells marked by expression of fli1a, but the role of Lamc3 has been unknown. Methods: We use antisense morpholino oligonucleotides, and CRISPR/Cas9 mutagenesis of F0 embryos, to create zebrafish embryos in which lamc3 expression is compromised. Transgenic imaging, immunofluorescence, and in situ hybridisation reveal that Lamc3 loss-of-function affects the development of muscle pioneers, endothelial cells, and motoneurons. Results: Lamc3 is enriched in endothelial cells during zebrafish development, but it is also expressed by other tissues. Depletion of Lamc3 by use of antisense morpholino oligonucleotides perturbs formation of the parachordal chain and subsequently the thoracic duct, but Lamc3 is not required for sprouting of the cardinal vein. F0 embryos in which lamc3 expression is perturbed by a CRISPR/Cas9 approach also fail to form a parachordal chain, but we were unable to establish a stable lamc3 null line. Lamc3 is dispensable for muscle pioneer specification and for the expression of netrin-1a in these cells. Lamc3 knockdown causes netrin-1a up-regulation in the neural tube and there is increased Netrin-1 protein throughout the trunk of the embryo. Axonal guidance of rostral primary motoneurons is defective in Lamc3 knockdown embryos. Conclusions: We suggest that knockdown of Lamc3 perturbs migration of rostral primary motoneurons at the level of the horizontal myoseptum, indicating that laminin γ3 plays a role in motoneuron guidance.

Primary Motor Neuron Culture to Promote Cellular Viability and Myelination.

A culture system that can recapitulate myelination in vitro will not only help us to better understand the mechanism of myelination and demyelination but also identify possible therapeutic interventions for treating demyelinating diseases. Here, we introduce a simple and reproducible myelination culture system using mouse motor neurons (MNs) and Schwann cells (SCs). Dissociated motor neurons are plated on a feeder layer of SCs, which interact with and wrap around the axons of MNs as they differentiate in culture. In our MN-SC co-culture system, MNs survive over 3weeks and extend long axons. Both viability and axon growth of MNs in the co-culture are markedly enhanced as compared to those of MN monocultures. Co-labeling of myelin basic proteins and neuronal cell microtubules reveals that SCs form myelin sheaths by wrapping around the axons of MNs.

Characterisation of the pathogenic effects of the in vivo expression of an ALS-linked mutation in D-amino acid oxidase: Phenotype and loss of spinal cord motor neurons.

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset neuromuscular disorder characterised by selective loss of motor neurons leading to fatal paralysis. Current therapeutic approaches are limited in their effectiveness. Substantial advances in understanding ALS disease mechanisms has come from the identification of pathogenic mutations in dominantly inherited familial ALS (FALS). We previously reported a coding mutation in D-amino acid oxidase (DAOR199W) associated with FALS. DAO metabolises D-serine, an essential co-agonist at the N-Methyl-D-aspartic acid glutamate receptor subtype (NMDAR). Using primary motor neuron cultures or motor neuron cell lines we demonstrated that expression of DAOR199W, promoted the formation of ubiquitinated protein aggregates, activated autophagy and increased apoptosis. The aim of this study was to characterise the effects of DAOR199W in vivo, using transgenic mice overexpressing DAOR199W. Marked abnormal motor features, e.g. kyphosis, were evident in mice expressing DAOR199W, which were associated with a significant loss (19%) of lumbar spinal cord motor neurons, analysed at 14 months. When separated by gender, this effect was greater in females (26%; p< 0.0132). In addition, we crossed the DAOR199W transgenic mouse line with the SOD1G93A mouse model of ALS to determine whether the effects of SOD1G93A were potentiated in the double transgenic line (DAOR199W/SOD1G93A). Although overall survival was not affected, onset of neurological signs was significantly earlier in female double transgenic animals than their female SOD1G93A littermates (125 days vs 131 days, P = 0.0239). In summary, some significant in vivo effects of DAOR199W on motor neuron function (i.e. kyphosis and loss of motor neurons) were detected which were most marked in females and could contribute to the earlier onset of neurological signs in double transgenic females compared to SOD1G93A littermates, highlighting the importance of recognizing gender effects present in animal models of ALS.

Knockdown of Laminin gamma-3 (Lamc3) impairs motoneuron guidance in the zebrafish embryo.

Background:Previous work in the zebrafish embryo has shown that laminin γ-3 ( lamc3) is enriched in endothelial cells marked by expression of fli1a, but the role of Lamc3 has been unknown. Methods: We use antisense morpholino oligonucleotides, and CRISPR/Cas9 mutagenesis of F0 embryos, to create zebrafish embryos in which lamc3 expression is compromised. Transgenic imaging, immunofluorescence, and in situ hybridisation reveal that Lamc3 loss-of-function affects the development of muscle pioneers, endothelial cells, and motoneurons. Results: Lamc3 is enriched in endothelial cells during zebrafish development, but it is also expressed by other tissues. Depletion of Lamc3 by use of antisense morpholino oligonucleotides perturbs formation of the parachordal chain and subsequently the thoracic duct, but Lamc3 is not required for sprouting of the cardinal vein. F0 embryos in which lamc3 expression is perturbed by a CRISPR/Cas9 approach also fail to form a parachordal chain, but we were unable to establish a stable lamc3 null line. Lamc3 is dispensable for muscle pioneer specification and for the expression of netrin-1a in these cells. Lamc3 knockdown causes netrin-1a up-regulation in the neural tube and there is increased Netrin-1 protein throughout the trunk of the embryo. Axonal guidance of rostral primary motoneurons is defective in Lamc3 knockdown embryos. Conclusions: We suggest that knockdown of Lamc3 perturbs migration of rostral primary motoneurons at the level of the horizontal myoseptum, indicating that laminin γ3 plays a role in motoneuron guidance.

Neurturin is a PGC-1α1-controlled myokine that promotes motor neuron recruitment and neuromuscular junction formation

ObjectiveWe examined whether skeletal muscle overexpression of PGC-1α1 or PGC-1α4 affected myokine secretion and neuromuscular junction (NMJ) formation. MethodsA microfluidic device was used to model endocrine signaling and NMJ formation between primary mouse myoblast-derived myotubes and embryonic stem cell-derived motor neurons. Differences in hydrostatic pressure allowed for fluidic isolation of either cell type or unidirectional signaling in the fluid phase. Myotubes were transduced to overexpress PGC-1α1 or PGC-1α4, and myokine secretion was quantified using a proximity extension assay. Morphological and functional changes in NMJs were measured by fluorescent microscopy and by monitoring muscle contraction upon motor neuron stimulation. ResultsSkeletal muscle transduction with PGC-1α1, but not PGC-1α4, increased NMJ formation and size. PGC-1α1 increased muscle secretion of neurturin, which was sufficient and necessary for the effects of muscle PGC-1α1 on NMJ formation. ConclusionsOur findings indicate that neurturin is a mediator of PGC-1α1-dependent retrograde signaling from muscle to motor neurons.

BDNF/trkB Induction of Calcium Transients through Cav2.2 Calcium Channels in Motoneurons Corresponds to F-actin Assembly and Growth Cone Formation on β2-Chain Laminin (221).

Spontaneous Ca2+ transients and actin dynamics in primary motoneurons correspond to cellular differentiation such as axon elongation and growth cone formation. Brain-derived neurotrophic factor (BDNF) and its receptor trkB support both motoneuron survival and synaptic differentiation. However, in motoneurons effects of BDNF/trkB signaling on spontaneous Ca2+ influx and actin dynamics at axonal growth cones are not fully unraveled. In our study we addressed the question how neurotrophic factor signaling corresponds to cell autonomous excitability and growth cone formation. Primary motoneurons from mouse embryos were cultured on the synapse specific, β2-chain containing laminin isoform (221) regulating axon elongation through spontaneous Ca2+ transients that are in turn induced by enhanced clustering of N-type specific voltage-gated Ca2+ channels (Cav2.2) in axonal growth cones. TrkB-deficient (trkBTK−/−) mouse motoneurons which express no full-length trkB receptor and wildtype motoneurons cultured without BDNF exhibited reduced spontaneous Ca2+ transients that corresponded to altered axon elongation and defects in growth cone morphology which was accompanied by changes in the local actin cytoskeleton. Vice versa, the acute application of BDNF resulted in the induction of spontaneous Ca2+ transients and Cav2.2 clustering in motor growth cones, as well as the activation of trkB downstream signaling cascades which promoted the stabilization of β-actin via the LIM kinase pathway and phosphorylation of profilin at Tyr129. Finally, we identified a mutual regulation of neuronal excitability and actin dynamics in axonal growth cones of embryonic motoneurons cultured on laminin-221/211. Impaired excitability resulted in dysregulated axon extension and local actin cytoskeleton, whereas upon β-actin knockdown Cav2.2 clustering was affected. We conclude from our data that in embryonic motoneurons BDNF/trkB signaling contributes to axon elongation and growth cone formation through changes in the local actin cytoskeleton accompanied by increased Cav2.2 clustering and local calcium transients. These findings may help to explore cellular mechanisms which might be dysregulated during maturation of embryonic motoneurons leading to motoneuron disease.

Post-transcriptional Inhibition of Hsc70-4/HSPA8 Expression Leads to Synaptic Vesicle Cycling Defects in Multiple Models of ALS

Amyotrophic lateral sclerosis (ALS) is a synaptopathy accompanied by the presence of cytoplasmic aggregates containing TDP-43, an RNA-binding protein linked to ∼97% of ALS cases. Using a Drosophila model of ALS, we show that TDP-43 overexpression (OE) in motor neurons results in decreased expression of the Hsc70-4 chaperone at the neuromuscular junction (NMJ). Mechanistically, mutant TDP-43 sequesters hsc70-4 mRNA and impairs its translation. Expression of the Hsc70-4 ortholog, HSPA8, is also reduced in primary motor neurons and NMJs of mice expressing mutant TDP-43. Electrophysiology, imaging, and genetic interaction experiments reveal TDP-43-dependent defects in synaptic vesicle endocytosis. These deficits can be partially restored by OE of Hsc70-4, cysteine-string protein (Csp), or dynamin. This suggests that TDP-43 toxicity results in part from impaired activity of the synaptic CSP/Hsc70 chaperone complex impacting dynamin function. Finally, Hsc70-4/HSPA8 expression is also post-transcriptionally reduced in fly and human induced pluripotent stem cell (iPSC) C9orf72 models, suggesting a common disease pathomechanism.