bims-axbals Biomed News
on Axonal Biology and ALS
Issue of 2024‒06‒02
25 papers selected by
TJ Krzystek, ALS Therapy Development Institute
  1. New developments in pre-clinical models of ALS to guide translation.
  2. Alternatively spliced ELAVL3 cryptic exon 4a causes ELAVL3 downregulation in ALS TDP-43 proteinopathy.
  3. ALS-linked C9orf72 dipeptide repeats inhibit starvation-induced autophagy through modulating BCL2-BECN1 interaction.
  4. Synaptic defects in a drosophila model of muscular dystrophy.
  5. Spinal inhibitory neurons degenerate before motor neurons and excitatory neurons in a mouse model of ALS.
  6. From use of omics to systems biology: Identifying therapeutic targets for amyotrophic lateral sclerosis.
  7. Generation of human induced pluripotent stem cell lines from sporadic, sporadic frontotemporal dementia, familial SOD1, and familial C9orf72 amyotrophic lateral sclerosis (ALS) patients.
  8. Targeting the autophagy-NAD axis protects against cell death in Niemann-Pick type C1 disease models.
  9. The role of Matrin-3 in physiology and its dysregulation in disease.
  10. Dysregulated Wnt and NFAT signaling in a Parkinson's disease LRRK2 G2019S knock-in model.
  11. RNP granules in ALS and neurodegeneration: From multifunctional membraneless organelles to therapeutic opportunities.
  12. Integrative multi-omic analysis reveals conserved cell-projection deficits in human Down syndrome brains.
  13. Single nucleotide polymorphisms in the cannabinoid CB2 receptor: Molecular pharmacology and disease associations.
  14. Actin polymerization and longitudinal actin fibers in axon initial segment plasticity.
  15. Use of biomarkers in clinical trials and future developments that will help identify novel biomarkers.
  16. Cell autonomous microglia defects in a stem cell model of frontotemporal dementia.
  17. Network motifs in cellular neurophysiology.
  18. A 3D Bioprinted Cortical Organoid Platform for Modeling Human Brain Development.
  19. Mitochondrial dysfunction heightens the integrated stress response to drive ALS pathogenesis.
  20. Axonal autophagic vesicle transport in the rat optic nerve in vivo under normal conditions and during acute axonal degeneration.
  21. Neuronal autosis is Na+/K+-ATPase alpha 3-dependent and involved in hypoxic-ischemic neuronal death.
  22. ANT2 functions as a translocon for mitochondrial cross-membrane translocation of RNAs.
  23. YAP and TAZ differentially regulate postnatal cortical progenitor proliferation and astrocyte differentiation.
  24. Ebselen analogues delay disease onset and its course in fALS by on-target SOD-1 engagement.
  25. C9orf72 controls hepatic lipid metabolism by regulating SREBP1 transport.
  1. Int Rev Neurobiol. 2024 ;pii: S0074-7742(24)00060-6. [Epub ahead of print]176 477-524
    New developments in pre-clinical models of ALS to guide translation.
    Lenja De Cock, Valérie Bercier, Ludo Van Den Bosch.
      Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder in which selective death of motor neurons leads to muscle weakness and paralysis. Most research has focused on understanding and treating monogenic familial forms, most frequently caused by mutations in SOD1, FUS, TARDBP and C9orf72, although ALS is mostly sporadic and without a clear genetic cause. Rodent models have been developed to study monogenic ALS, but despite numerous pre-clinical studies and clinical trials, few disease-modifying therapies are available. ALS is a heterogeneous disease with complex underlying mechanisms where several genes and molecular pathways appear to play a role. One reason for the high failure rate of clinical translation from the current models could be oversimplification in pre-clinical studies. Here, we review advances in pre-clinical models to better capture the heterogeneous nature of ALS and discuss the value of novel model systems to guide translation and aid in the development of precision medicine.
    Keywords:  ALS; Amyotrophic lateral sclerosis; IPSCs; Neurodegeneration; Pre-clinical modelling; Precision medicine; Rodents; Xenografts; Zebrafish
    DOI:  https://doi.org/10.1016/bs.irn.2024.04.008
  2. Acta Neuropathol. 2024 May 30. 147(1): 93
    Alternatively spliced ELAVL3 cryptic exon 4a causes ELAVL3 downregulation in ALS TDP-43 proteinopathy.
    Isabel Costantino, Alex Meng, John Ravits.
      
    DOI:  https://doi.org/10.1007/s00401-024-02732-y
  3. Acta Pharm Sin B. 2024 May;14(5): 2026-2038
    ALS-linked C9orf72 dipeptide repeats inhibit starvation-induced autophagy through modulating BCL2-BECN1 interaction.
    Shiqiang Xu, Qilian Ma, Junwen Shen, Ningning Li, Shan Sun, Nana Wang, Yang Chen, Chunsheng Dong, Kin Yip Tam, Jochen H M Prehn, Hongfeng Wang, Zheng Ying.
      Growing evidences indicate that dysfunction of autophagy contributes to the disease pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two neurodegenerative disorders. The GGGGCC·GGCCCC repeat RNA expansion in chromosome 9 open reading frame 72 (C9orf72) is the most genetic cause of both ALS and FTD. According to the previous studies, GGGGCC·GGCCCC repeat undergoes the unconventional repeat-associated non-ATG translation, which produces dipeptide repeat (DPR) proteins. Although there is a growing understanding that C9orf72 DPRs have a strong ability to harm neurons and induce C9orf72-linked ALS/FTD, whether these DPRs can affect autophagy remains unclear. In the present study, we find that poly-GR and poly-PR, two arginine-containing DPRs which display the most cytotoxic properties according to the previous studies, strongly inhibit starvation-induced autophagy. Moreover, our data indicate that arginine-rich DPRs enhance the interaction between BCL2 and BECN1/Beclin 1 by inhibiting BCL2 phosphorylation, therefore they can impair autophagic clearance of neurodegenerative disease-associated protein aggregates under starvation condition in cells. Importantly, our study not only highlights the role of C9orf72 DPR in autophagy dysfunction, but also provides novel insight that pharmacological intervention of autophagy using SW063058, a small molecule compound that can disrupt the interaction between BECN1 and BCL2, may reduce C9orf72 DPR-induced neurotoxicity.
    Keywords:  Amyotrophic lateral sclerosis; Autophagy; BCL2; BECN1/Beclin 1; C9orf72; Dipeptide repeat; Frontotemporal dementia; Neurodegeneration
    DOI:  https://doi.org/10.1016/j.apsb.2024.02.004
  4. Front Cell Neurosci. 2024 ;18 1381112
    Synaptic defects in a drosophila model of muscular dystrophy.
    Jessica M Sidisky, Alex Winters, Russell Caratenuto, Daniel T Babcock.
      Muscular dystrophies are a devastating class of diseases that result in a progressive loss of muscle integrity. Duchenne Muscular Dystrophy, the most prevalent form of Muscular Dystrophy, is due to the loss of functional Dystrophin. While much is known regarding destruction of muscle tissue in these diseases, much less is known regarding the synaptic defects that also occur in these diseases. Synaptic defects are also among the earliest hallmarks of neurodegenerative diseases, including the neuromuscular disease Amyotrophic Lateral Sclerosis (ALS). Our current study investigates synaptic defects within adult muscle tissues as well as presynaptic motor neurons in Drosophila dystrophin mutants. Here we demonstrate that the progressive, age-dependent loss of flight ability in dystrophin mutants is accompanied by disorganization of Neuromuscular Junctions (NMJs), including impaired localization of both presynaptic and postsynaptic markers. We show that these synaptic defects, including presynaptic defects within motor neurons, are due to the loss of Dystrophin specifically within muscles. These results should help to better understand the early synaptic defects preceding cell loss in neuromuscular disorders.
    Keywords:  degeneration; dystrophin; flight; neuromuscular junction; postsynaptic; presynaptic
    DOI:  https://doi.org/10.3389/fncel.2024.1381112
  5. Sci Adv. 2024 May 31. 10(22): eadk3229
    Spinal inhibitory neurons degenerate before motor neurons and excitatory neurons in a mouse model of ALS.
    Roser Montañana-Rosell, Raghavendra Selvan, Pablo Hernández-Varas, Jan M Kaminski, Simrandeep Kaur Sidhu, Dana B Ahlmark, Ole Kiehn, Ilary Allodi.
      Amyotrophic lateral sclerosis (ALS) is characterized by the progressive loss of somatic motor neurons. A major focus has been directed to motor neuron intrinsic properties as a cause for degeneration, while less attention has been given to the contribution of spinal interneurons. In the present work, we applied multiplexing detection of transcripts and machine learning-based image analysis to investigate the fate of multiple spinal interneuron populations during ALS progression in the SOD1G93A mouse model. The analysis showed that spinal inhibitory interneurons are affected early in the disease, before motor neuron death, and are characterized by a slow progressive degeneration, while excitatory interneurons are affected later with a steep progression. Moreover, we report differential vulnerability within inhibitory and excitatory subpopulations. Our study reveals a strong interneuron involvement in ALS development with interneuron specific degeneration. These observations point to differential involvement of diverse spinal neuronal circuits that eventually may be determining motor neuron degeneration.
    DOI:  https://doi.org/10.1126/sciadv.adk3229
  6. Int Rev Neurobiol. 2024 ;pii: S0074-7742(24)00021-7. [Epub ahead of print]176 209-268
    From use of omics to systems biology: Identifying therapeutic targets for amyotrophic lateral sclerosis.
    Lydia Castelli, Rosario Vasta, Scott P Allen, Rachel Waller, Adriano Chiò, Bryan J Traynor, Janine Kirby.
      Amyotrophic lateral sclerosis (ALS) is a heterogeneous progressive neurodegenerative disorder with available treatments such as riluzole and edaravone extending survival by an average of 3-6 months. The lack of highly effective, widely available therapies reflects the complexity of ALS. Omics technologies, including genomics, transcriptomic and proteomics have contributed to the identification of biological pathways dysregulated and targeted by therapeutic strategies in preclinical and clinical trials. Integrating clinical, environmental and neuroimaging information with omics data and applying a systems biology approach can further improve our understanding of the disease with the potential to stratify patients and provide more personalised medicine. This chapter will review the omics technologies that contribute to a systems biology approach and how these components have assisted in identifying therapeutic targets. Current strategies, including the use of genetic screening and biosampling in clinical trials, as well as the future application of additional technological advances, will also be discussed.
    Keywords:  Amyotrophic Lateral Sclerosis; Environment; Genomics; Metabolomics; Microbiome; Neuroimaging; Omics; Proteomics; Systems Biology; Transcriptomics
    DOI:  https://doi.org/10.1016/bs.irn.2024.02.001
  7. Stem Cell Res. 2024 May 23. pii: S1873-5061(24)00145-4. [Epub ahead of print]78 103447
    Generation of human induced pluripotent stem cell lines from sporadic, sporadic frontotemporal dementia, familial SOD1, and familial C9orf72 amyotrophic lateral sclerosis (ALS) patients.
    Leanne Jiang, Timothy J Tracey, Melinder K Gill, Stephanie L Howe, Dominique T Power, Vanda Bharti, Pamela A McCombe, Robert D Henderson, Frederik J Steyn, Shyuan T Ngo.
      Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Clinical heterogeneity and complex genetics pose challenges to understanding disease mechanisms and producing effective cures. To model clinical heterogeneity, we generated human induced pluripotent stem cells (iPSCs) from two sporadic ALS patients (sporadic ALS and sporadic ALS with frontotemporal dementia), two familial ALS patients (familial SOD1 mutation positive and familial C9orf72 repeat expansion positive), and four age- and sex-matched healthy controls. These iPSCs can be used to generate 2D and 3D in vitro models of ALS to investigate mechanisms of disease and screen for therapeutics.
    DOI:  https://doi.org/10.1016/j.scr.2024.103447
  8. Cell Death Dis. 2024 May 31. 15(5): 382
    Targeting the autophagy-NAD axis protects against cell death in Niemann-Pick type C1 disease models.
    Tetsushi Kataura, Lucia Sedlackova, Congxin Sun, Gamze Kocak, Niall Wilson, Peter Banks, Faisal Hayat, Sergey Trushin, Eugenia Trushina, Oliver D K Maddocks, John E Oblong, Satomi Miwa, Masaya Imoto, Shinji Saiki, Daniel Erskine, Marie E Migaud, Sovan Sarkar, Viktor I Korolchuk.
      Impairment of autophagy leads to an accumulation of misfolded proteins and damaged organelles and has been implicated in plethora of human diseases. Loss of autophagy in actively respiring cells has also been shown to trigger metabolic collapse mediated by the depletion of nicotinamide adenine dinucleotide (NAD) pools, resulting in cell death. Here we found that the deficit in the autophagy-NAD axis underpins the loss of viability in cell models of a neurodegenerative lysosomal storage disorder, Niemann-Pick type C1 (NPC1) disease. Defective autophagic flux in NPC1 cells resulted in mitochondrial dysfunction due to impairment of mitophagy, leading to the depletion of both the reduced and oxidised forms of NAD as identified via metabolic profiling. Consequently, exhaustion of the NAD pools triggered mitochondrial depolarisation and apoptotic cell death. Our chemical screening identified two FDA-approved drugs, celecoxib and memantine, as autophagy activators which effectively restored autophagic flux, NAD levels, and cell viability of NPC1 cells. Of biomedical relevance, either pharmacological rescue of the autophagy deficiency or NAD precursor supplementation restored NAD levels and improved the viability of NPC1 patient fibroblasts and induced pluripotent stem cell (iPSC)-derived cortical neurons. Together, our findings identify the autophagy-NAD axis as a mechanism of cell death and a target for therapeutic interventions in NPC1 disease, with a potential relevance to other neurodegenerative disorders.
    DOI:  https://doi.org/10.1038/s41419-024-06770-y
  9. Biochem Soc Trans. 2024 May 30. pii: BST20220585. [Epub ahead of print]
    The role of Matrin-3 in physiology and its dysregulation in disease.
    Macy L Sprunger, Meredith E Jackrel.
      The dysfunction of many RNA-binding proteins (RBPs) that are heavily disordered, including TDP-43 and FUS, are implicated in amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). These proteins serve many important roles in the cell, and their capacity to form biomolecular condensates (BMCs) is key to their function, but also a vulnerability that can lead to misregulation and disease. Matrin-3 (MATR3) is an intrinsically disordered RBP implicated both genetically and pathologically in ALS/FTD, though it is relatively understudied as compared with TDP-43 and FUS. In addition to binding RNA, MATR3 also binds DNA and is implicated in many cellular processes including the DNA damage response, transcription, splicing, and cell differentiation. It is unclear if MATR3 localizes to BMCs under physiological conditions, which is brought further into question due to its lack of a prion-like domain. Here, we review recent studies regarding MATR3 and its roles in numerous physiological processes, as well as its implication in a range of diseases.
    Keywords:  Matrin-3; RNA-binding proteins; amyotrophic lateral sclerosis; biomolecular condensates; intrinsically disordered proteins; neurodegeneration
    DOI:  https://doi.org/10.1042/BST20220585
  10. Sci Rep. 2024 05 29. 14(1): 12393
    Dysregulated Wnt and NFAT signaling in a Parkinson's disease LRRK2 G2019S knock-in model.
    Andrea Wetzel, Si Hang Lei, Tiansheng Liu, Michael P Hughes, Yunan Peng, Tristan McKay, Simon N Waddington, Simone Grannò, Ahad A Rahim, Kirsten Harvey.
      Parkinson's disease (PD) is a progressive late-onset neurodegenerative disease leading to physical and cognitive decline. Mutations of leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of PD. LRRK2 is a complex scaffolding protein with known regulatory roles in multiple molecular pathways. Two prominent examples of LRRK2-modulated pathways are Wingless/Int (Wnt) and nuclear factor of activated T-cells (NFAT) signaling. Both are well described key regulators of immune and nervous system development as well as maturation. The aim of this study was to establish the physiological and pathogenic role of LRRK2 in Wnt and NFAT signaling in the brain, as well as the potential contribution of the non-canonical Wnt/Calcium pathway. In vivo cerebral Wnt and NFATc1 signaling activity was quantified in LRRK2 G2019S mutant knock-in (KI) and LRRK2 knockout (KO) male and female mice with repeated measures over 28 weeks, employing lentiviral luciferase biosensors, and analyzed using a mixed-effect model. To establish spatial resolution, we investigated tissues, and primary neuronal cell cultures from different brain regions combining luciferase signaling activity, immunohistochemistry, qPCR and western blot assays. Results were analyzed by unpaired t-test with Welch's correction or 2-way ANOVA with post hoc corrections. In vivo Wnt signaling activity in LRRK2 KO and LRRK2 G2019S KI mice was increased significantly ~ threefold, with a more pronounced effect in males (~ fourfold) than females (~ twofold). NFATc1 signaling was reduced ~ 0.5-fold in LRRK2 G2019S KI mice. Brain tissue analysis showed region-specific expression changes in Wnt and NFAT signaling components. These effects were predominantly observed at the protein level in the striatum and cerebral cortex of LRRK2 KI mice. Primary neuronal cell culture analysis showed significant genotype-dependent alterations in Wnt and NFATc1 signaling under basal and stimulated conditions. Wnt and NFATc1 signaling was primarily dysregulated in cortical and hippocampal neurons respectively. Our study further built on knowledge of LRRK2 as a Wnt and NFAT signaling protein. We identified complex changes in neuronal models of LRRK2 PD, suggesting a role for mutant LRRK2 in the dysregulation of NFAT, and canonical and non-canonical Wnt signaling.
    Keywords:  Immune system; LRRK2; LRRK2 G2019S; LRRK2 KO; Mouse models; NFAT signaling; Parkinson’s diseases; Primary cultures; Sex differences; Wnt signaling
    DOI:  https://doi.org/10.1038/s41598-024-63130-8
  11. Int Rev Neurobiol. 2024 ;pii: S0074-7742(24)00061-8. [Epub ahead of print]176 455-479
    RNP granules in ALS and neurodegeneration: From multifunctional membraneless organelles to therapeutic opportunities.
    Tatyana A Shelkovnikova, Guillaume M Hautbergue.
      Amyotrophic lateral sclerosis (ALS) and related neurodegenerative diseases are characterised by dysfunction of a host of RNA-binding proteins (RBPs) and a severely disrupted RNA metabolism. Recently, RBP-harbouring phase-separated complexes, ribonucleoprotein (RNP) granules, have come into the limelight as "crucibles" of neuronal pathology in ALS. RNP granules are indispensable for the multitude of regulatory processes underlying cellular RNA metabolism and serve as critical organisers of cellular biochemistry. Neurons, highly specialised cells, heavily rely on RNP granules for efficient trafficking, signalling and stress responses. Multiple RNP granule components, primarily RBPs such as TDP-43 and FUS, are affected by ALS mutations. However, even in the absence of mutations, RBP proteinopathies represent pathophysiological hallmarks of ALS. Given the high local concentrations of RBPs and RNAs, their weakened or enhanced interactions within RNP granules disrupt their homeostasis. Thus, the physiological process of phase separation and RNP granule formation, vital for maintaining the high-functioning state of neuronal cells, becomes their Achilles heel. Here, we will review the recent literature on the causes and consequences of abnormal RNP granule functioning in ALS and related disorders. In particular, we will summarise the evidence for the network-level dysfunction of RNP granules in these conditions and discuss considerations for therapeutic interventions to target RBPs, RNP granules and their network as a whole.
    Keywords:  ALS; Membraneless organelle; Neurodegeneration; RNA-binding protein; Ribonucleoprotein complex; Therapeutic strategy
    DOI:  https://doi.org/10.1016/bs.irn.2024.04.009
  12. Neuron. 2024 May 21. pii: S0896-6273(24)00329-5. [Epub ahead of print]
    Integrative multi-omic analysis reveals conserved cell-projection deficits in human Down syndrome brains.
    Mohit Rastogi, Martina Bartolucci, Marina Nanni, Michelangelo Aloisio, Diego Vozzi, Andrea Petretto, Andrea Contestabile, Laura Cancedda.
      Down syndrome (DS) is the most common genetic cause of cognitive disability. However, it is largely unclear how triplication of a small gene subset may impinge on diverse aspects of DS brain physiopathology. Here, we took a multi-omic approach and simultaneously analyzed by RNA-seq and proteomics the expression signatures of two diverse regions of human postmortem DS brains. We found that the overexpression of triplicated genes triggered global expression dysregulation, differentially affecting transcripts, miRNAs, and proteins involved in both known and novel biological candidate pathways. Among the latter, we observed an alteration in RNA splicing, specifically modulating the expression of genes involved in cytoskeleton and axonal dynamics in DS brains. Accordingly, we found an alteration in axonal polarization in neurons from DS human iPSCs and mice. Thus, our study provides an integrated multilayer expression database capable of identifying new potential targets to aid in designing future clinical interventions for DS.
    Keywords:  Down syndrome; RNA-binding proteins; alternative splicing; axonogenesis; cell projection; miRNA; neurodevelopment; neuronal polarization; proteomics; transcriptomics
    DOI:  https://doi.org/10.1016/j.neuron.2024.05.002
  13. Br J Pharmacol. 2024 May 27.
    Single nucleotide polymorphisms in the cannabinoid CB2 receptor: Molecular pharmacology and disease associations.
    Tahira Foyzun, Maddie Whiting, Kate K Velasco, Jessie C Jacobsen, Mark Connor, Natasha L Grimsey.
      Preclinical evidence implicating cannabinoid receptor 2 (CB2) in various diseases has led researchers to question whether CB2 genetics influence aetiology or progression. Associations between conditions and genetic loci are often studied via single nucleotide polymorphism (SNP) prevalence in case versus control populations. In the CNR2 coding exon, ~36 SNPs have high overall population prevalence (minor allele frequencies [MAF] ~37%), including non-synonymous SNP (ns-SNP) rs2501432 encoding CB2 63Q/R. Interspersed are ~27 lower frequency SNPs, four being ns-SNPs. CNR2 introns also harbour numerous SNPs. This review summarises CB2 ns-SNP molecular pharmacology and evaluates evidence from ~70 studies investigating CB2 genetic variants with proposed linkage to disease. Although CNR2 genetic variation has been associated with a wide variety of conditions, including osteoporosis, immune-related disorders, and mental illnesses, further work is required to robustly validate CNR2 disease links and clarify specific mechanisms linking CNR2 genetic variation to disease pathophysiology and potential drug responses.
    Keywords:  biological variation, population; biomarkers; drug development; genetics; polymorphism, single nucleotide; receptor, cannabinoid, CB2; signal transduction
    DOI:  https://doi.org/10.1111/bph.16383
  14. Front Mol Neurosci. 2024 ;17 1376997
    Actin polymerization and longitudinal actin fibers in axon initial segment plasticity.
    David Micinski, Pirta Hotulainen.
      The location of the axon initial segment (AIS) at the junction between the soma and axon of neurons makes it instrumental in maintaining neural polarity and as the site for action potential generation. The AIS is also capable of large-scale relocation in an activity-dependent manner. This represents a form of homeostatic plasticity in which neurons regulate their own excitability by changing the size and/or position of the AIS. While AIS plasticity is important for proper functionality of AIS-containing neurons, the cellular and molecular mechanisms of AIS plasticity are poorly understood. Here, we analyzed changes in the AIS actin cytoskeleton during AIS plasticity using 3D structured illumination microscopy (3D-SIM). We showed that the number of longitudinal actin fibers increased transiently 3 h after plasticity induction. We further showed that actin polymerization, especially formin mediated actin polymerization, is required for AIS plasticity and formation of longitudinal actin fibers. From the formin family of proteins, Daam1 localized to the ends of longitudinal actin fibers. These results indicate that active re-organization of the actin cytoskeleton is required for proper AIS plasticity.
    Keywords:  AIS plasticity; actin; axon initial segment (AIS); formin; plasticity; super-resolution
    DOI:  https://doi.org/10.3389/fnmol.2024.1376997
  15. Int Rev Neurobiol. 2024 ;pii: S0074-7742(24)00062-X. [Epub ahead of print]176 171-207
    Use of biomarkers in clinical trials and future developments that will help identify novel biomarkers.
    Andrea Malaspina.
      Engineering new solutions for therapeutic benefit in Amyotrophic Lateral Sclerosis (ALS) has proved a difficult task to accomplish. This is largely the reflection of complexities at multiple levels, that require solutions to improve cost-effectiveness and outcomes. The main obstacle related to the condition's clinical heterogeneity, chiefly the broad difference in survival observed among ALS patients, imposes large populations studies and long follow-up to evaluate any efficacy. The emerging solution is composite clinical and biological parameters enabling prognostic stratification into homogeneous phenotypes for more affordable studies. From a therapeutic development perspective, the choice of a medicinal product requires the availability of treatment-specific biomarkers of target engagement to identify off-target effects based on the compound's putative modality of action. More importantly, there are no established biomarkers of treatment response that can complement clinical outcome measures and support futility and end of treatment analyses of efficacy. Ultimately the onus rests on the development of biomarkers encompassing the unmet needs of clinical trial design, from inclusion to efficacy. These readouts of the pathological process may be used in combination with clinical and paraclinical outcome measured, significantly reducing the time and financial burden of clinical studies. Progress towards a biomarker-driven clinical trial design in ALS has been possible thanks to the accurate detection of neurofilaments and of other immunological mediators in biological fluids with the disease progression, a step change enabling the testing of novel therapeutic agents in a new clinical trial setting. However, further progress remains to be made to find treatment specific target engagement biomarkers along with readouts of treatment response that can be reliably applied to all emerging therapies and clinical studies. Here we will cover the basic notions of biomarker development in ALS clinical trials, the most crucial unanswered questions and the unmet needs in the ALS biomarkers space.
    Keywords:  ALS (Amyotrophic Lateral Sclerosis); Biomarkers; Clinical Outcome Measures; Clinical Trials; Immunological Mediators; Neurofilaments; Prognostic Stratification; Target Engagement; Therapeutic Development; Treatment Response
    DOI:  https://doi.org/10.1016/bs.irn.2024.04.010
  16. medRxiv. 2024 May 16. pii: 2024.05.15.24307444. [Epub ahead of print]
    Cell autonomous microglia defects in a stem cell model of frontotemporal dementia.
    Abhirami K Iyer, Lisa Vermunt, Farzaneh S Mirfakhar, Miguel Minaya, Mariana Acquarone, Rama Krishna Koppisetti, Arun Renganathan, Shih-Feng You, Emma P Danhash, Anthony Verbeck, Grant Galasso, Scott M Lee, Jacob Marsh, Alissa L Nana, Salvatore Spina, William W Seeley, Lea T Grinberg, Sally Temple, Charlotte E Teunissen, Chihiro Sato, Celeste M Karch.
      Neuronal dysfunction has been extensively studied as a central feature of neurodegenerative tauopathies. However, across neurodegenerative diseases, there is strong evidence for active involvement of immune cells like microglia in driving disease pathophysiology. Here, we demonstrate that tau mRNA and protein are expressed in microglia in human brains and in human induced pluripotent stem cell (iPSC)-derived microglia like cells (iMGLs). Using iMGLs harboring the MAPT IVS10+16 mutation and isogenic controls, we demonstrate that a tau mutation is sufficient to alter microglial transcriptional states. We discovered that MAPT IVS10+16 microglia exhibit cytoskeletal abnormalities, stalled phagocytosis, disrupted TREM2/TYROBP networks, and altered metabolism. Additionally, we found that secretory factors from MAPT IVS10+16 iMGLs impact neuronal health, reducing synaptic density in neurons. Key features observed in vitro were recapitulated in human brain tissue and cerebrospinal fluid from MAPT mutations carriers. Together, our findings that MAPT IVS10+16 drives cell-intrinsic dysfunction in microglia that impacts neuronal health has major implications for development of therapeutic strategies.
    DOI:  https://doi.org/10.1101/2024.05.15.24307444
  17. Trends Neurosci. 2024 May 27. pii: S0166-2236(24)00077-8. [Epub ahead of print]
    Network motifs in cellular neurophysiology.
    Divyansh Mittal, Rishikesh Narayanan.
      Concepts from network science and graph theory, including the framework of network motifs, have been frequently applied in studying neuronal networks and other biological complex systems. Network-based approaches can also be used to study the functions of individual neurons, where cellular elements such as ion channels and membrane voltage are conceptualized as nodes within a network, and their interactions are denoted by edges. Network motifs in this context provide functional building blocks that help to illuminate the principles of cellular neurophysiology. In this review we build a case that network motifs operating within neurons provide tools for defining the functional architecture of single-neuron physiology and neuronal adaptations. We highlight the presence of such computational motifs in the cellular mechanisms underlying action potential generation, neuronal oscillations, dendritic integration, and neuronal plasticity. Future work applying the network motifs perspective may help to decipher the functional complexities of neurons and their adaptation during health and disease.
    Keywords:  complex system; degeneracy; dendrite; feedback; neural computation; neuronal plasticity
    DOI:  https://doi.org/10.1016/j.tins.2024.04.008
  18. Adv Healthc Mater. 2024 May 30. e2401603
    A 3D Bioprinted Cortical Organoid Platform for Modeling Human Brain Development.
    Melissa A Cadena, Anson Sing, Kylie Taylor, Linqi Jin, Liqun Ning, Mehdi Salar Amoli, Yamini Singh, The Brain Organoid Hub, Samantha N Lanjewar, Martin L Tomov, Vahid Serpooshan, Steven A Sloan.
      The ability to promote three-dimensional (3D) self-organization of induced pluripotent stem cells into complex tissue structures called organoids presents new opportunities for the field of developmental biology. Brain organoids have been used to investigate principles of neurodevelopment and neuropsychiatric disorders and serve as a drug screening and discovery platform. However, brain organoid cultures are currently limited by a lacking ability to precisely control their extracellular environment. Here, we employed 3D bioprinting to generate a high-throughput, tunable, and reproducible scaffold for controlling organoid development and patterning. Additionally, our approach supports the co-culture of organoids and vascular cells in a custom architecture containing interconnected endothelialized channels. Printing fidelity and mechanical assessments confirm that fabricated scaffolds closely match intended design features and exhibit stiffness values reflective of the developing human brain. Using organoid growth, viability, cytoarchitecture, proliferation, and transcriptomic benchmarks, we found that organoids cultured within the bioprinted scaffold long-term are healthy and have expected neuroectodermal differentiation. Lastly, we confirmed that the endothelial cells in printed channel structures can migrate towards and infiltrate into the embedded organoids. This work demonstrates a tunable 3D culturing platform that can be used to create more complex and accurate models of human brain development and underlying diseases. This article is protected by copyright. All rights reserved.
    Keywords:  3D bioprinting; brain organoids; extracellular matrix; induced pluripotent stem cells; vasculature
    DOI:  https://doi.org/10.1002/adhm.202401603
  19. bioRxiv. 2024 May 14. pii: 2024.05.13.594000. [Epub ahead of print]
    Mitochondrial dysfunction heightens the integrated stress response to drive ALS pathogenesis.
    Curran Landry, James Costanzo, Miguel Mitne-Neto, Mayana Zatz, Ashleigh Schaffer, Maria Hatzoglou, Alysson Muotri, Helen Cristina Miranda.
      Vesicle-associated membrane protein-associated protein-B (VAPB) is an ER membrane bound protein. VAPB P56S causes a dominant, familial form of amyotrophic lateral sclerosis (ALS), however, the mechanism through which this mutation causes motor neuron (MN) disease remains unknown. Using inducible wild type (WT) and VAPB P56S expressing iPSC-derived MNs we show that VAPB P56S, but not WT, protein decreased neuronal firing and mitochondrial-ER contact (MERC) with an associated age-dependent decrease in mitochondrial membrane potential (MMP); all typical characteristics of MN-disease. We further show that VAPB P56S expressing iPSC-derived MNs have enhanced age-dependent sensitivity to ER stress. We identified elevated expression of the master regulator of the Integrated Stress Response (ISR) marker ATF4 and decreased protein synthesis in the VAPB P56S iPSC-derived MNs. Chemical inhibition of ISR with the compound, ISRIB, rescued all MN disease phenotype in VAPB P56S MNs. Thus, our results not only support ISR inhibition as a potential therapeutic target for ALS patients, but also provides evidence to pathogenesis.
    DOI:  https://doi.org/10.1101/2024.05.13.594000
  20. Acta Neuropathol Commun. 2024 May 29. 12(1): 82
    Axonal autophagic vesicle transport in the rat optic nerve in vivo under normal conditions and during acute axonal degeneration.
    Xiaoyue Luo, Jiong Zhang, Johan Tolö, Sebastian Kügler, Uwe Michel, Mathias Bähr, Jan Christoph Koch.
      Neurons pose a particular challenge to degradative processes like autophagy due to their long and thin processes. Autophagic vesicles (AVs) are formed at the tip of the axon and transported back to the soma. This transport is essential since the final degradation of the vesicular content occurs only close to or in the soma. Here, we established an in vivo live-imaging model in the rat optic nerve using viral vector mediated LC3-labeling and two-photon-microscopy to analyze axonal transport of AVs. Under basal conditions in vivo, 50% of the AVs are moving with a majority of 85% being transported in the retrograde direction. Transport velocity is higher in the retrograde than in the anterograde direction. A crush lesion of the optic nerve results in a rapid breakdown of retrograde axonal transport while the anterograde transport stays intact over several hours. Close to the lesion site, the formation of AVs is upregulated within the first 6 h after crush, but the clearance of AVs and the levels of lysosomal markers in the adjacent axon are reduced. Expression of p150Glued, an adaptor protein of dynein, is significantly reduced after crush lesion. In vitro, fusion and colocalization of the lysosomal marker cathepsin D with AVs are reduced after axotomy. Taken together, we present here the first in vivo analysis of axonal AV transport in the mammalian CNS using live-imaging. We find that axotomy leads to severe defects of retrograde motility and a decreased clearance of AVs via the lysosomal system.
    Keywords:  Autophagy; Axonal transport; Axotomy; Dynactin; Optic nerve; p150Glued
    DOI:  https://doi.org/10.1186/s40478-024-01791-2
  21. Cell Death Dis. 2024 May 25. 15(5): 363
    Neuronal autosis is Na+/K+-ATPase alpha 3-dependent and involved in hypoxic-ischemic neuronal death.
    Pauline Depierre, Vanessa Ginet, Anita C Truttmann, Julien Puyal.
      Macroautophagy (hereafter called autophagy) is an essential physiological process of degradation of organelles and long-lived proteins. The discovery of autosis, a Na+/K+-ATPase (ATP1)-dependent type of autophagic cell death with specific morphological and biochemical features, has strongly contributed to the acceptance of a pro-death role of autophagy. However, the occurrence and relevance of autosis in neurons has never been clearly investigated, whereas we previously provided evidence that autophagy mechanisms could be involved in neuronal death in different in vitro and in vivo rodent models of hypoxia-ischemia (HI) and that morphological features of autosis were observed in dying neurons following rat perinatal cerebral HI. In the present study, we demonstrated that neuronal autosis could occur in primary cortical neurons using two different stimulations enhancing autophagy flux and neuronal death: a neurotoxic concentration of Tat-BECN1 (an autophagy-inducing peptide) and a hypoxic/excitotoxic stimulus (mimicking neuronal death induced by cerebral HI). Both stimulations induce autophagic neuronal death (dependent on canonical autophagic genes and independent on apoptotic, necroptotic or ferroptotic pathways) with all morphological and biochemical (ATP1a-dependent) features of autosis. However, we demonstrated that autosis is not dependent on the ubiquitous subunit ATP1a1 in neurons, as in dividing cell types, but on the neuronal specific ATP1a3 subunit. We also provided evidence that, in different in vitro and in vivo models where autosis is induced, ATP1a3-BECN1 interaction is increased and prevented by cardiac glycosides treatment. Interestingly, an increase in ATP1a3-BECN1 interaction is also detected in dying neurons in the autoptic brains of human newborns with severe hypoxic-ischemic encephalopathy (HIE). Altogether, these results suggest that ATP1a3-BECN1-dependent autosis could play an important role in neuronal death in HI conditions, paving the way for the development of new neuroprotective strategies in hypoxic-ischemic conditions including in severe case of human HIE.
    DOI:  https://doi.org/10.1038/s41419-024-06750-2
  22. Cell Res. 2024 May 29.
    ANT2 functions as a translocon for mitochondrial cross-membrane translocation of RNAs.
    Pengcheng Wang, Lixiao Zhang, Siyi Chen, Renjian Li, Peipei Liu, Xiang Li, Hongdi Luo, Yujia Huo, Zhirong Zhang, Yiqi Cai, Xu Liu, Jinliang Huang, Guangkeng Zhou, Zhe Sun, Shanwei Ding, Jiahao Shi, Zizhuo Zhou, Ruoxi Yuan, Liang Liu, Sipeng Wu, Geng Wang.
      Bidirectional transcription of mammalian mitochondrial DNA generates overlapping transcripts that are capable of forming double-stranded RNA (dsRNA) structures. Release of mitochondrial dsRNA into the cytosol activates the dsRNA-sensing immune signaling, which is a defense mechanism against microbial and viral attack and possibly cancer, but could cause autoimmune diseases when unchecked. A better understanding of the process is vital in therapeutic application of this defense mechanism and treatment of cognate human diseases. In addition to exporting dsRNAs, mitochondria also export and import a variety of non-coding RNAs. However, little is known about how these RNAs are transported across mitochondrial membranes. Here we provide direct evidence showing that adenine nucleotide translocase-2 (ANT2) functions as a mammalian RNA translocon in the mitochondrial inner membrane, independent of its ADP/ATP translocase activity. We also show that mitochondrial dsRNA efflux through ANT2 triggers innate immunity. Inhibiting this process alleviates inflammation in vivo, providing a potential therapeutic approach for treating autoimmune diseases.
    DOI:  https://doi.org/10.1038/s41422-024-00978-5
  23. J Cell Sci. 2024 May 15. pii: jcs261516. [Epub ahead of print]137(10):
    YAP and TAZ differentially regulate postnatal cortical progenitor proliferation and astrocyte differentiation.
    Jessie Chen, Yung-Hsu Tsai, Anne K Linden, John A Kessler, Chian-Yu Peng.
      WW domain-containing transcription regulator 1 (WWTR1, referred to here as TAZ) and Yes-associated protein (YAP, also known as YAP1) are transcriptional co-activators traditionally studied together as a part of the Hippo pathway, and are best known for their roles in stem cell proliferation and differentiation. Despite their similarities, TAZ and YAP can exert divergent cellular effects by differentially interacting with other signaling pathways that regulate stem cell maintenance or differentiation. In this study, we show in mouse neural stem and progenitor cells (NPCs) that TAZ regulates astrocytic differentiation and maturation, and that TAZ mediates some, but not all, of the effects of bone morphogenetic protein (BMP) signaling on astrocytic development. By contrast, both TAZ and YAP mediate the effects on NPC fate of β1-integrin (ITGB1) and integrin-linked kinase signaling, and these effects are dependent on extracellular matrix cues. These findings demonstrate that TAZ and YAP perform divergent functions in the regulation of astrocyte differentiation, where YAP regulates cell cycle states of astrocytic progenitors and TAZ regulates differentiation and maturation from astrocytic progenitors into astrocytes.
    Keywords:  Astrocytes; BMP; Integrins; Neural stem cells; TAZ; YAP
    DOI:  https://doi.org/10.1242/jcs.261516
  24. Sci Rep. 2024 05 27. 14(1): 12118
    Ebselen analogues delay disease onset and its course in fALS by on-target SOD-1 engagement.
    Seiji Watanabe, Kangsa Amporndanai, Raheela Awais, Caroline Latham, Muhammad Awais, Paul M O'Neill, Koji Yamanaka, S Samar Hasnain.
      Amyotrophic lateral sclerosis (ALS) selectively affects motor neurons. SOD1 is the first causative gene to be identified for ALS and accounts for at least 20% of the familial (fALS) and up to 4% of sporadic (sALS) cases globally with some geographical variability. The destabilisation of the SOD1 dimer is a key driving force in fALS and sALS. Protein aggregation resulting from the destabilised SOD1 is arrested by the clinical drug ebselen and its analogues (MR6-8-2 and MR6-26-2) by redeeming the stability of the SOD1 dimer. The in vitro target engagement of these compounds is demonstrated using the bimolecular fluorescence complementation assay with protein-ligand binding directly visualised by co-crystallography in G93A SOD1. MR6-26-2 offers neuroprotection slowing disease onset of SOD1G93A mice by approximately 15 days. It also protected neuromuscular junction from muscle denervation in SOD1G93A mice clearly indicating functional improvement.
    Keywords:  Amyotrophic lateral sclerosis; Drug development; Ebselen; Motor neuron disease; Riluzole; Superoxide dismutase; Target engagement
    DOI:  https://doi.org/10.1038/s41598-024-62903-5
  25. Cell Death Differ. 2024 May 30.
    C9orf72 controls hepatic lipid metabolism by regulating SREBP1 transport.
    Yachen Wu, Wenzhong Zheng, Guofeng Xu, Lijun Zhu, Zhiqiang Li, Jincao Chen, Lianrong Wang, Shi Chen.
      Sterol regulatory element binding transcription factors (SREBPs) play a crucial role in lipid homeostasis. They are processed and transported to the nucleus via COPII, where they induce the expression of lipogenic genes. COPII maintains the homeostasis of organelles and plays an essential role in the protein secretion pathways in eukaryotes. The formation of COPII begins at endoplasmic reticulum exit sites (ERES), and is regulated by SEC16A, which provides a platform for the assembly of COPII. However, there have been few studies on the changes in SEC16A protein levels. The repetitive expansion of the hexanucleotide sequence GGGGCC within the chromosome 9 open reading frame 72 (C9orf72) gene is a prevalent factor in the development of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here, we found that the absence of C9orf72 leads to a decrease in SEC16A protein levels, resulting in reduced localization of the guanine nucleotide exchange factor SEC12 at the ERES. Consequently, the small GTP binding protein SAR1 is unable to bind the endoplasmic reticulum normally, impairing the assembly of COPII. Ultimately, the disruption of SREBPs transport decreases de novo lipogenesis. These results suggest that C9orf72 acts as a novel role in regulating lipid homeostasis and may serve as a potential therapeutic target for obesity.
    DOI:  https://doi.org/10.1038/s41418-024-01312-7
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