bims-axbals 2023-11-19 papers

bims-axbals

Biomed News

on Axonal Biology and ALS

Issue of 2023‒11‒19
twenty papers selected by
TJ Krzystek, ALS Therapy Development Institute

Induced pluripotent stem cells-based disease modeling, drug screening, clinical trials, and reverse translational research for amyotrophic lateral sclerosis.
Breaking barriers with tofersen: Enhancing therapeutic opportunities in amyotrophic lateral sclerosis.
Targeting Progranulin as an Immuno-Neurology Therapeutic Approach.
Differential effect of Fas activation on spinal muscular atrophy motoneuron death and induction of axonal growth.
Neuronal dysfunction caused by FUSR521G promotes ALS-associated phenotypes that are attenuated by NF-κB inhibition.
Targeting stress granules in neurodegenerative diseases: A focus on biological function and dynamics disorders.
Mapping the landscape of lineage-specific dynamic regulation of gene expression using single-cell transcriptomics and application to genetics of complex disease.
Mitigating aberrant Cdk5 activation alleviates mitochondrial defects and motor neuron disease symptoms in spinal muscular atrophy.
How to differentiate induced pluripotent stem cells into sensory neurons for disease modelling: a comparison of two protocols.
Heterogeneity of cortical pTDP-43 inclusion morphologies in amyotrophic lateral sclerosis.
Multi-modal proteomic characterization of lysosomal function and proteostasis in progranulin-deficient neurons.
A case for non-coding RNA as a suitable biomarker of amyotrophic lateral sclerosis.
Precise Therapeutic Targeting of Distinct NRXN1+/- Mutations.
Neural-driven activation of 3D muscle within a finite element framework: exploring applications in healthy and neurodegenerative simulations.
Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS.
Longitudinal course of neurofilament light chain levels in amyotrophic lateral sclerosis-insights from a completed randomized controlled trial with rasagiline.
New tools can propel research in lysosomal storage diseases.
Microtubule stabilising peptides: new paradigm towards management of neuronal disorders.
iPSC-derived microglia carrying the TREM2 R47H/+ mutation are proinflammatory and promote synapse loss.
Human skeletal muscle organoids model fetal myogenesis and sustain uncommitted PAX7 myogenic progenitors.

J Neurochem. 2023 Nov 12.

Induced pluripotent stem cells-based disease modeling, drug screening, clinical trials, and reverse translational research for amyotrophic lateral sclerosis.

Hideyuki Okano, Satoru Morimoto, Chris Kato, Jin Nakahara, Shinichi Takahashi.

  It has been more than 10 years since the hopes for disease modeling and drug discovery using induced pluripotent stem cell (iPSC) technology boomed. Recently, clinical trials have been conducted with drugs identified using this technology, and some promising results have been reported. For amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, several groups have identified candidate drugs, ezogabine (retigabine), bosutinib, and ropinirole, using iPSCs-based drug discovery, and clinical trials using these drugs have been conducted, yielding interesting results. In our previous study, an iPSCs-based drug repurposing approach was utilized to show the potential of ropinirole hydrochloride (ROPI) in reducing ALS-specific pathological phenotypes. Recently, a phase 1/2a trial was conducted to investigate the effects of ropinirole on ALS further. This double-blind, randomized, placebo-controlled study confirmed the safety and tolerability of and provided evidence of its ability to delay disease progression and prolong the time to respiratory failure in ALS patients. Furthermore, in the reverse translational research, in vitro characterization of patient-derived iPSCs-motor neurons (MNs) mimicked the therapeutic effects of ROPI in vivo, suggesting the potential application of this technology to the precision medicine of ALS. Interestingly, RNA-seq data showed that ROPI treatment suppressed the sterol regulatory element-binding protein 2-dependent cholesterol biosynthesis pathway. Therefore, this pathway may be involved in the therapeutic effect of ROPI on ALS. The possibility that this pathway may be involved in the therapeutic effect of ALS was demonstrated. Finally, new future strategies for ALS using iPSCs technology will be discussed in this paper.

Keywords:  amyotrophic lateral sclerosis (ALS); clinical trials; induced pluripotent stem cell (iPSC); motor neurons (MNs); ropinirole hydrochloride (ROPI); sterol regulatory element-binding protein 2 (SREBP2)

DOI:  https://doi.org/10.1111/jnc.16005
Eur J Neurol. 2023 Nov 17.

Breaking barriers with tofersen: Enhancing therapeutic opportunities in amyotrophic lateral sclerosis.

Aniket Saini, Pooja A Chawla.

  BACKGROUND AND PURPOSE: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that primarily affects adults, characterized by muscle weakness resulting from the specific death of motor neurons in the spinal cord and brain. The pathogenesis of ALS is associated with the accumulation of mutant superoxide dismutase 1 (SOD1) proteins and neurofilaments in motor neurons, highlighting the critical need for disease-modifying treatments. Current therapies, such as riluzole and edaravone, provide only symptomatic relief. Recently, tofersen gained approval from the US FDA under the brand name Qalsody as the first and only gene therapy for ALS, addressing a significant pathological aspect of the disease.METHODS: We carried out a literature survey using PubMed, Scopus, National Institutes of Health, and Biogen for articles published in the English language concerned with "amyotrophic lateral sclerosis", pathophysiology, current treatment, treatment under clinical trial, and the newly approved drug "tofersen" and its detailed summary.
RESULTS: A comprehensive review of the literature on the pathophysiology, available treatment, and newly approved drug for this condition revealed convincing evidence that we are now able to better monitor and treat ALS.
CONCLUSIONS: Although treatment of ALS is difficult, the newly approved drug tofersen has emerged as a potential therapy to slow down the progression of ALS by targeting SOD1 mRNA, representing a significant advancement in the treatment of ALS.

Keywords:  ALS; FDA-approved drugs; adverse drug reactions; amyotrophic lateral sclerosis; clinical trial; tofersen

DOI:  https://doi.org/10.1111/ene.16140
Int J Mol Sci. 2023 Nov 03. pii: 15946. [Epub ahead of print]24(21):

Targeting Progranulin as an Immuno-Neurology Therapeutic Approach.

Maria A Boylan, Andrew Pincetic, Gary Romano, Nadine Tatton, Sara Kenkare-Mitra, Arnon Rosenthal.

  Immuno-neurology is an emerging therapeutic strategy for dementia and neurodegeneration designed to address immune surveillance failure in the brain. Microglia, as central nervous system (CNS)-resident myeloid cells, routinely perform surveillance of the brain and support neuronal function. Loss-of-function (LOF) mutations causing decreased levels of progranulin (PGRN), an immune regulatory protein, lead to dysfunctional microglia and are associated with multiple neurodegenerative diseases, including frontotemporal dementia caused by the progranulin gene (GRN) mutation (FTD-GRN), Alzheimer's disease (AD), Parkinson's disease (PD), limbic-predominant age-related transactivation response deoxyribonucleic acid binding protein 43 (TDP-43) encephalopathy (LATE), and amyotrophic lateral sclerosis (ALS). Immuno-neurology targets immune checkpoint-like proteins, offering the potential to convert aging and dysfunctional microglia into disease-fighting cells that counteract multiple disease pathologies, clear misfolded proteins and debris, promote myelin and synapse repair, optimize neuronal function, support astrocytes and oligodendrocytes, and maintain brain vasculature. Several clinical trials are underway to elevate PGRN levels as one strategy to modulate the function of microglia and counteract neurodegenerative changes associated with various disease states. If successful, these and other immuno-neurology drugs have the potential to revolutionize the treatment of neurodegenerative disorders by harnessing the brain's immune system and shifting it from an inflammatory/pathological state to an enhanced physiological/homeostatic state.

Keywords:  PGRN; frontotemporal dementia; immuno-neurology; neuroimmunology; neuroinflammation

DOI:  https://doi.org/10.3390/ijms242115946
Cell Mol Biol (Noisy-le-grand). 2023 Oct 31. 69(10): 1-8

Differential effect of Fas activation on spinal muscular atrophy motoneuron death and induction of axonal growth.

Salim Benlefki, Richard Younes, Désiré Challuau, Nathalie Bernard-Marissal, Cécile Hilaire, Frédérique Scamps, Melissa Bowerman, Rashmi Kothary, Bernard L Schneider, Cedric Raoul.

Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are the most common motoneuron diseases affecting adults and infants, respectively. ALS and SMA are both characterized by the selective degeneration of motoneurons. Although different in their genetic etiology, growing evidence indicates that they share molecular and cellular pathogenic signatures that constitute potential common therapeutic targets. We previously described a motoneuron-specific death pathway elicited by the Fas death receptor, whereby vulnerable ALS motoneurons show an exacerbated sensitivity to Fas activation. However, the mechanisms that drive the loss of SMA motoneurons remains poorly understood. Here, we describe an in vitro model of SMA-associated degeneration using primary motoneurons derived from Smn2B/- SMA mice and show that Fas activation selectively triggers death of the proximal motoneurons. Fas-induced death of SMA motoneurons has the molecular signature of the motoneuron-selective Fas death pathway that requires activation of p38 kinase, caspase-8, -9 and -3 as well as upregulation of collapsin response mediator protein 4 (CRMP4). In addition, Rho-associated Kinase (ROCK) is required for Fas recruitment. Remarkably, we found that exogenous activation of Fas also promotes axonal elongation in both wildtype and SMA motoneurons. Axon outgrowth of motoneurons promoted by Fas requires the activity of ERK, ROCK and caspases. This work defines a dual role of Fas signaling in motoneurons that can elicit distinct responses from cell death to axonal growth.

DOI: https://doi.org/10.14715/cmb/2023.69.10.1
Acta Neuropathol Commun. 2023 Nov 16. 11(1): 182

Neuronal dysfunction caused by FUSR521G promotes ALS-associated phenotypes that are attenuated by NF-κB inhibition.

Mari Carmen Pelaez, Antoine Desmeules, Pauline A Gelon, Bastien Glasson, Laetitia Marcadet, Alicia Rodgers, Daniel Phaneuf, Silvia Pozzi, Paul A Dutchak, Jean-Pierre Julien, Chantelle F Sephton.

  Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are related neurodegenerative diseases that belong to a common disease spectrum based on overlapping clinical, pathological and genetic evidence. Early pathological changes to the morphology and synapses of affected neuron populations in ALS/FTD suggest a common underlying mechanism of disease that requires further investigation. Fused in sarcoma (FUS) is a DNA/RNA-binding protein with known genetic and pathological links to ALS/FTD. Expression of ALS-linked FUS mutants in mice causes cognitive and motor defects, which correlate with loss of motor neuron dendritic branching and synapses, in addition to other pathological features of ALS/FTD. The role of ALS-linked FUS mutants in causing ALS/FTD-associated disease phenotypes is well established, but there are significant gaps in our understanding of the cell-autonomous role of FUS in promoting structural changes to motor neurons, and how these changes relate to disease progression. Here we generated a neuron-specific FUS-transgenic mouse model expressing the ALS-linked human FUSR521G variant, hFUSR521G/Syn1, to investigate the cell-autonomous role of FUSR521G in causing loss of dendritic branching and synapses of motor neurons, and to understand how these changes relate to ALS-associated phenotypes. Longitudinal analysis of mice revealed that cognitive impairments in juvenile hFUSR521G/Syn1 mice coincide with reduced dendritic branching of cortical motor neurons in the absence of motor impairments or changes in the neuromorphology of spinal motor neurons. Motor impairments and dendritic attrition of spinal motor neurons developed later in aged hFUSR521G/Syn1 mice, along with FUS cytoplasmic mislocalisation, mitochondrial abnormalities and glial activation. Neuroinflammation promotes neuronal dysfunction and drives disease progression in ALS/FTD. The therapeutic effects of inhibiting the pro-inflammatory nuclear factor kappa B (NF-κB) pathway with an analog of Withaferin A, IMS-088, were assessed in symptomatic hFUSR521G/Syn1 mice and were found to improve cognitive and motor function, increase dendritic branches and synapses of motor neurons, and attenuate other ALS/FTD-associated pathological features. Treatment of primary cortical neurons expressing FUSR521G with IMS-088 promoted the restoration of dendritic mitochondrial numbers and mitochondrial activity to wild-type levels, suggesting that inhibition of NF-κB permits the restoration of mitochondrial stasis in our models. Collectively, this work demonstrates that FUSR521G has a cell-autonomous role in causing early pathological changes to dendritic and synaptic structures of motor neurons, and that these changes precede motor defects and other well-known pathological features of ALS/FTD. Finally, these findings provide further support that modulation of the NF-κB pathway in ALS/FTD is an important therapeutic approach to attenuate disease.

Keywords:  Amyotrophic lateral sclerosis (ALS); Cell-autonomous; Dendrite; Frontotemporal dementia (FTD); Fused in sarcoma (FUS); Mitochondria; Motor neuron disease (MND); Nuclear factor kappa B (NF-κB); Synapse; Synaptopathy

DOI:  https://doi.org/10.1186/s40478-023-01671-1
Biofactors. 2023 Nov 15.

Targeting stress granules in neurodegenerative diseases: A focus on biological function and dynamics disorders.

Minglv Fang, Ying Liu, Cheng Huang, Shengjie Fan.

  Stress granules (SGs) are membraneless organelles formed by eukaryotic cells in response to stress to promote cell survival through their pleiotropic cytoprotective effects. SGs recruit a variety of components to enhance their physiological function, and play a critical role in the propagation of pathological proteins, a key factor in neurodegeneration. Recent advances indicate that SG dynamic disorders exacerbate neuronal susceptibility to stress in neurodegenerative diseases (NDs) including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Huntington's disease (HD) and Parkinson's disease (PD). Here, we outline the biological functions of SGs, highlight SG dynamic disorders in NDs, and emphasize therapeutic approaches for enhancing SG dynamics to provide new insights into ND intervention.

Keywords:  Alzheimer's disease; amyotrophic lateral sclerosis; neurodegeneration; stress granules

DOI:  https://doi.org/10.1002/biof.2017
medRxiv. 2023 Oct 25. pii: 2023.10.24.23297476. [Epub ahead of print]

Mapping the landscape of lineage-specific dynamic regulation of gene expression using single-cell transcriptomics and application to genetics of complex disease.

Hanna Abe, Phillip Lin, Dan Zhou, Douglas M Ruderfer, Eric R Gamazon.

Single-cell transcriptome data can provide insights into how genetic variation influences biological processes involved in human biology and disease. However, the identification of gene-level associations in distinct cell types faces several challenges, including the limited reference resource from population scale studies, data sparsity in single-cell RNA sequencing, and the complex cell-state pattern of expression within individual cell types. Here we develop genetic models of cell type specific and cell state adjusted gene expression in dopaminergic neurons in the process of specializing from induced pluripotent stem cells. The resulting framework quantifies the dynamics of the genetic regulation of gene expression and estimates its cell type specificity. As an application, we show that the approach detects known and new genes associated with schizophrenia and enables insights into context-dependent disease mechanisms. We provide a genomic resource from a phenome-wide application of our models to more than 1500 phenotypes from the UK Biobank. Using longitudinal genetically determined expression, we implement a predictive causality framework, evaluating the prediction of future values of a target gene expression using prior values of a putative regulatory gene. Collectively, this work demonstrates the insights that can be gained into the molecular underpinnings of diseases by quantifying the genetic control of gene expression at single-cell resolution.

DOI: https://doi.org/10.1101/2023.10.24.23297476
Proc Natl Acad Sci U S A. 2023 Nov 21. 120(47): e2300308120

Mitigating aberrant Cdk5 activation alleviates mitochondrial defects and motor neuron disease symptoms in spinal muscular atrophy.

Nimrod Miller, Zhaofa Xu, Katharina A Quinlan, Amy Ji, Jered V McGivern, Zhihua Feng, Han Shi, Chien-Ping Ko, Li-Huei Tsai, Charles J Heckman, Allison D Ebert, Yongchao C Ma.

  Spinal muscular atrophy (SMA), the top genetic cause of infant mortality, is characterized by motor neuron degeneration. Mechanisms underlying SMA pathogenesis remain largely unknown. Here, we report that the activity of cyclin-dependent kinase 5 (Cdk5) and the conversion of its activating subunit p35 to the more potent activator p25 are significantly up-regulated in mouse models and human induced pluripotent stem cell (iPSC) models of SMA. The increase of Cdk5 activity occurs before the onset of SMA phenotypes, suggesting that it may be an initiator of the disease. Importantly, aberrant Cdk5 activation causes mitochondrial defects and motor neuron degeneration, as the genetic knockout of p35 in an SMA mouse model rescues mitochondrial transport and fragmentation defects, and alleviates SMA phenotypes including motor neuron hyperexcitability, loss of excitatory synapses, neuromuscular junction denervation, and motor neuron degeneration. Inhibition of the Cdk5 signaling pathway reduces the degeneration of motor neurons derived from SMA mice and human SMA iPSCs. Altogether, our studies reveal a critical role for the aberrant activation of Cdk5 in SMA pathogenesis and suggest a potential target for therapeutic intervention.

Keywords:  Cdk5; mitochondria; motor neuron; neurodegeneration; spinal muscular atrophy

DOI:  https://doi.org/10.1073/pnas.2300308120
Res Sq. 2023 Oct 28. pii: rs.3.rs-3127017. [Epub ahead of print]

How to differentiate induced pluripotent stem cells into sensory neurons for disease modelling: a comparison of two protocols.

Anil Kumar Kalia, Corinna Rösseler, Rafael Granja-Vazquez, Ayesha Ahmad, Joseph J Pancrazio, Anika Neureiter, Mei Zhang, Daniel Sauter, Irina Vetter, Asa Andersson, Gregory Dussor, Theodore J Price, Benedict J Kolber, Vincent Truong, Patrick Walsh, Angelika Lampert.

Background Human induced pluripotent stem cell (iPSC)-derived peripheral sensory neurons present a valuable tool to model human diseases and are a source for applications in drug discovery and regenerative medicine. Clinically, peripheral sensory neuropathies can result in maladies ranging from a complete loss of pain to severe painful neuropathic symptoms. Sensory neurons are located in the dorsal root ganglion and are comprised of functionally diverse neuronal types. Low efficiency, reproducibility concerns, variations arising due to genetic factors and time needed to generate functionally mature neuronal populations from iPSCs for disease modelling remain key challenges to study human nociception in vitro . Here, we report a detailed characterization of iPSC-derived sensory neurons with an accelerated differentiation protocol ("Anatomic" protocol) compared to the most commonly used small molecule approach ("Chambers" protocol). Methods Multiple iPSC clones derived from different reprogramming methods, genetics, age, and somatic cell sources were used to generate sensory neurons. Expression profiling of sensory neurons was performed with Immunocytochemistry and in situ hybridization techniques. Manual patch clamp and high throughput cellular screening systems (Fluorescence imaging plate reader, automated patch clamp and multi-well microelectrode arrays recordings) were applied to functionally characterize the generated sensory neurons. Results The Anatomic protocol rendered a purer culture without the use of mitomycin C to suppress non-neuronal outgrowth, while Chambers differentiations yielded a mix of cell types. High throughput systems confirmed functional expression of Na + and K + ion channels. Multi-well microelectrode recordings display spontaneously active neurons with sensitivity to increased temperature indicating expression of heat sensitive ion channels. Patient-derived nociceptors displayed higher frequency firing compared to control subject with both, Chambers and Anatomic differentiation approaches, underlining their potential use for clinical phenotyping as a disease-in-a-dish model. Conclusions We validated the efficiency of two differentiation protocols and their potential application for understanding the disease mechanisms from patients suffering from pain disorders. We propose that both differentiation methods can be further exploited for understanding mechanisms and development of novel treatments in pain disorders.

DOI: https://doi.org/10.21203/rs.3.rs-3127017/v1
Acta Neuropathol Commun. 2023 Nov 13. 11(1): 180

Heterogeneity of cortical pTDP-43 inclusion morphologies in amyotrophic lateral sclerosis.

Rachel H Tan, Heather McCann, Claire E Shepherd, Monica Pinkerton, Srestha Mazumder, Emma M Devenney, Gabrielle L Adler, Dominic B Rowe, Jillian Kril, Glenda M Halliday, Matthew C Kiernan.

  BACKGROUND: Despite the presence of significant cortical pTDP-43 inclusions of heterogeneous morphologies in patients diagnosed with amyotrophic lateral sclerosis (ALS), pathological subclassification is routinely performed in the minority of patients with concomitant frontotemporal dementia (FTD).OBJECTIVE: In order to improve current understanding of the presence and relevance of pathological pTDP-43 subtypes in ALS, the present study examined the pattern of cortical pTDP-43 aggregates in 61 ALS cases without FTD.
RESULTS: Based on the presence, morphology and composition of pTDP-43 pathology, three distinct ALS-TDP subtypes were delineated: (1) A predominant pattern of pTDP-43 granulofilamentous neuronal inclusions (GFNIs) and grains that were immuno-negative for p62 was identified in 18% of cases designated ALS-TDP type E; (2) neuronal cytoplasmic inclusions (NCIs) that were immuno-positive for both pTDP-43 and p62 were observed in 67% of cases assigned ALS-TDP type B; and (3) scarce cortical pTDP-43 and p62 aggregates were identified in 15% of cases coined ALS-TDP type SC (scarce cortical). Quantitative analyses revealed a significantly greater burden of pTDP-43 GFNI and grains in ALS-TDP type E. Principal component analysis demonstrated significant relationships between GFNIs, grains and ALS-TDP subtypes to support the distinction of subtypes E and B. No significant difference in age at death or disease duration was found between ALS-TDP subgroups to suggest that these subtypes represent earlier or later stages of the same disease process. Instead, a significantly higher ALS-TDP stage, indicating greater topographical spread of pTDP-43, was identified in ALS-TDP type E. Alzheimer's disease neuropathological change (ABC score ≥ intermediate) and Lewy body disease (Braak stage ≥ IV) was more prevalent in the ALS-TDP type SC cohort, which also demonstrated a significantly lower overall cognitive score.
CONCLUSION: In summary, the present study demonstrates that ALS-TDP does not represent a single homogenous neuropathology. We propose the subclassification of ALS-TDP into three distinct subtypes using standard immuno-stains for pTDP-43 and p62 in the motor cortex, which is routinely sampled and evaluated for diagnostic neuropathological characterisation of ALS. We propose that future studies specify both clinicopathological group and pTDP-43 subtype to advance current understanding of the pathogenesis of clinical phenotypes in pTDP-43 proteinopathies, which will have significant relevance to the development of targeted therapies for this heterogeneous disorder.

Keywords:  Amyotrophic lateral sclerosis; Frontotemporal lobar degeneration; pTDP-43

DOI:  https://doi.org/10.1186/s40478-023-01670-2
Mol Neurodegener. 2023 Nov 16. 18(1): 87

Multi-modal proteomic characterization of lysosomal function and proteostasis in progranulin-deficient neurons.

Saadia Hasan, Michael S Fernandopulle, Stewart W Humble, Ashley M Frankenfield, Haorong Li, Ryan Prestil, Kory R Johnson, Brent J Ryan, Richard Wade-Martins, Michael E Ward, Ling Hao.

  BACKGROUND: Progranulin (PGRN) is a lysosomal glycoprotein implicated in various neurodegenerative diseases, including frontotemporal dementia and neuronal ceroid lipofuscinosis. Over 70 mutations discovered in the GRN gene all result in reduced expression of the PGRN protein. Genetic and functional studies point toward a regulatory role for PGRN in lysosome functions. However, the detailed molecular function of PGRN within lysosomes and the impact of PGRN deficiency on lysosomes remain unclear.METHODS: We developed multifaceted proteomic techniques to characterize the dynamic lysosomal biology in living human neurons and fixed mouse brain tissues. Using lysosome proximity labeling and immuno-purification of intact lysosomes, we characterized lysosome compositions and interactome in both human induced pluripotent stem cell (iPSC)-derived glutamatergic neurons (i3Neurons) and mouse brains. Using dynamic stable isotope labeling by amino acids in cell culture (dSILAC) proteomics, we measured global protein half-lives in human i3Neurons for the first time.
RESULTS: Leveraging the multi-modal proteomics and live-cell imaging techniques, we comprehensively characterized how PGRN deficiency changes the molecular and functional landscape of neuronal lysosomes. We found that PGRN loss impairs the lysosome's degradative capacity with increased levels of v-ATPase subunits on the lysosome membrane, increased hydrolases within the lysosome, altered protein regulations related to lysosomal transport, and elevated lysosomal pH. Consistent with impairments in lysosomal function, GRN-null i3Neurons and frontotemporal dementia patient-derived i3Neurons carrying GRN mutation showed pronounced alterations in protein turnover, such as cathepsins and proteins related to supramolecular polymerization and inherited neurodegenerative diseases.
CONCLUSION: This study suggested PGRN as a critical regulator of lysosomal pH and degradative capacity, which influences global proteostasis in neurons. Beyond the study of progranulin deficiency, these newly developed proteomic methods in neurons and brain tissues provided useful tools and data resources for the field to study the highly dynamic neuronal lysosome biology.

Keywords:  Frontotemporal dementia; Half-life; Lysosome; Neuron; PGRN; Progranulin; Proteomics; Turnover; dSILAC; iPSC

DOI:  https://doi.org/10.1186/s13024-023-00673-w
Expert Rev Mol Diagn. 2023 Nov 14. 1-3

A case for non-coding RNA as a suitable biomarker of amyotrophic lateral sclerosis.

Greig Joilin, Majid Hafezparast.



Keywords:  Amyotrophic lateral sclerosis; biomarkers; microRNA; motor neurone disease; non-coding RNA

DOI:  https://doi.org/10.1080/14737159.2023.2283522
bioRxiv. 2023 Oct 28. pii: 2023.10.28.564543. [Epub ahead of print]

Precise Therapeutic Targeting of Distinct NRXN1+/- Mutations.

Michael B Fernando, Yu Fan, Yanchun Zhang, Sarah Kammourh, Aleta N Murphy, Sadaf Ghorbani, Ryan Onatzevitch, Adriana Pero, Christopher Padilla, Lei Cao, Sarah Williams, Gang Fang, Paul A Slesinger, Kristen J Brennand.

As genetic studies continue to identify risk loci that are significantly associated with risk for neuropsychiatric disease, a critical unanswered question is the extent to which diverse mutations--sometimes impacting the same gene--will require common or individually tailored therapeutic strategies. Here we consider this in the context of rare, heterozygous, and non-recurrent copy number variants (2p16.3) linked to a variety of neuropsychiatric disorders that impact NRXN1 , a pre-synaptic cell adhesion protein that serves as a critical synaptic organizer in the brain. Complex patterns of NRXN1 alternative splicing are fundamental to establishing diverse neurocircuitry, vary between the cell types of the brain, and are differentially impacted by unique patient-specific (non-recurrent) deletions. Progress towards precision medicine may require restoring each person's NRXN1 isoform repertoires in a cell-type-specific manner. Towards this, here we contrast the cell-type-specific impact of unique patient-specific mutations in NRXN1 using human induced pluripotent stem cells. Perturbations in NRXN1 splicing causally lead to divergent cell-type-specific synaptic outcomes: whereas NRXN1 +/- deletions result in a decrease in synaptic activity throughout glutamatergic neuron maturation, there is an unexpected increase in synaptic activity in immature GABAergic neurons. Both glutamatergic and GABAergic synaptic deficits reflect independent loss-of-function (LOF) and gain-of-function (GOF) splicing defects. Towards clinical relevance, we show that treatment with β-estradiol increases NRXN1 expression in glutamatergic neurons, while antisense oligonucleotides knockdown mutant isoform expression across both glutamatergic and GABAergic neurons. Direct or indirect manipulation of NRXN1 splicing isoforms provides a promising therapeutic strategy for treating humans with 2p16.3 deletions.

DOI: https://doi.org/10.1101/2023.10.28.564543
Comput Methods Biomech Biomed Engin. 2023 Nov 15. 1-11

Neural-driven activation of 3D muscle within a finite element framework: exploring applications in healthy and neurodegenerative simulations.

Colton D Babcock, Victoria L Volk, Wei Zeng, Landon D Hamilton, Kevin B Shelburne, Clare K Fitzpatrick.

  This paper presents a novel computational framework for neural-driven finite element muscle models, with an application to amyotrophic lateral sclerosis (ALS). The multiscale neuromusculoskeletal (NMS) model incorporates physiologically accurate motor neurons, 3D muscle geometry, and muscle fiber recruitment. It successfully predicts healthy muscle force and tendon elongation and demonstrates a progressive decline in muscle force due to ALS, dropping from 203 N (healthy) to 155 N (120 days after ALS onset). This approach represents a preliminary step towards developing integrated neural and musculoskeletal simulations to enhance our understanding of neurodegenerative and neurodevelopmental conditions through predictive NMS models.

Keywords:  Neuromuscular modeling; finite element; muscle activation; neural-driven; neurodegenerative

DOI:  https://doi.org/10.1080/10255842.2023.2280772
Proc Natl Acad Sci U S A. 2023 Nov 21. 120(47): e2315347120

Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS.

Seiji Watanabe, Yuri Murata, Yasuyoshi Oka, Kotaro Oiwa, Mai Horiuchi, Yohei Iguchi, Okiru Komine, Akira Sobue, Masahisa Katsuno, Tomoo Ogi, Koji Yamanaka.

  The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in cellular homeostasis. We previously reported that MAM disruption is a common pathological feature in amyotrophic lateral sclerosis (ALS); however, the precise role of MAM in ALS was uncovered. Here, we show that the MAM is essential for TANK-binding kinase 1 (TBK1) activation under proteostatic stress conditions. A MAM-specific E3 ubiquitin ligase, autocrine motility factor receptor, ubiquitinated nascent proteins to activate TBK1 at the MAM, which results in ribosomal protein degradation. MAM or TBK1 deficiency under proteostatic stress conditions resulted in increased cellular vulnerability in vitro and motor impairment in vivo. Thus, MAM disruption exacerbates proteostatic stress via TBK1 inactivation in ALS. Our study has revealed a proteostatic mechanism mediated by the MAM-TBK1 axis, highlighting the physiological importance of the organelle contact sites.

Keywords:  TANK-binding kinase 1; amyotrophic lateral sclerosis; mitochondria-associated membrane; sigma-1 receptor; stress granules

DOI:  https://doi.org/10.1073/pnas.2315347120
Eur J Neurol. 2023 Nov 17.

Longitudinal course of neurofilament light chain levels in amyotrophic lateral sclerosis-insights from a completed randomized controlled trial with rasagiline.

Simon Witzel, Jeffrey M Statland, Petra Steinacker, Markus Otto, Johannes Dorst, Joachim Schuster, Richard J Barohn, Albert C Ludolph.

  BACKGROUND AND PURPOSE: Rasagiline might be disease modifying in patients with amyotrophic lateral sclerosis (ALS). The aim was to evaluate the effect of rasagiline 2 mg/day on neurofilament light chain (NfL), a prognostic biomarker in ALS.METHODS: In 65 patients with ALS randomized in a 3:1 ratio to rasagiline 2 mg/day (n = 48) or placebo (n = 17) in a completed randomized controlled multicentre trial, NfL levels in plasma were measured at baseline, month 6 and month 12. Longitudinal changes in NfL levels were evaluated regarding treatment and clinical parameters.
RESULTS: Baseline NfL levels did not differ between the study arms and correlated with disease progression rates both pre-baseline (r = 0.64, p < 0.001) and during the study (r = 0.61, p < 0.001). NfL measured at months 6 and 12 did not change significantly from baseline in both arms, with a median individual NfL change of +1.4 pg/mL (interquartile range [IQR] -5.6, 14.2) across all follow-up time points. However, a significant difference in NfL change at month 12 was observed between patients with high and low NfL baseline levels treated with rasagiline (high [n = 13], -6.9 pg/mL, IQR -20.4, 6.0; low [n = 18], +5.9 pg/mL, IQR -1.4, 19.7; p = 0.025). Additionally, generally higher longitudinal NfL variability was observed in patients with high baseline levels, whereas disease progression rates and disease duration at baseline had no impact on the longitudinal NfL course.
CONCLUSION: Post hoc NfL measurements in completed clinical trials are helpful in interpreting NfL data from ongoing and future interventional trials and could provide hypothesis-generating complementary insights. Further studies are warranted to ultimately differentiate NfL response to treatment from other factors.

Keywords:  amyotrophic lateral sclerosis; clinical trial design; neurofilament light; rasagiline

DOI:  https://doi.org/10.1111/ene.16154
Mol Genet Metab. 2023 Nov 03. pii: S1096-7192(23)00359-1. [Epub ahead of print]140(4): 107729

New tools can propel research in lysosomal storage diseases.

Ellen Hertz, Logan M Glasstetter, Yu Chen, Ellen Sidransky.

  Historically, the clinical manifestations of lysosomal storage diseases offered an early glimpse into the essential digestive functions of the lysosome. However, it was only recently that the more subtle role of this organelle in the dynamic regulation of multiple cellular processes was appreciated. With the need for precise interrogation of lysosomal interplay in health and disease comes the demand for more sophisticated functional tools. This demand has recently been met with 1) induced pluripotent stem cell-derived models that recapitulate the disease phenotype in vitro, 2) methods for lysosome affinity purification coupled with downstream omics analysis that provide a high-resolution snapshot of lysosomal alterations, and 3) gene editing and CRISPR/Cas9-based functional genomic strategies that enable screening for genetic modifiers of the disease phenotype. These emerging methods have garnered much interest in the field of neurodegeneration and their use in the field of metabolic disorders is now also steadily gaining momentum. Looking forward, these robust tools should accelerate basic science efforts to understand lysosomal dysfunction distal to substrate accumulation and provide translational opportunities to identify disease-modifying therapies.

Keywords:  CRISPR; Induced pluripotent stem cells (iPSC); Lyso-IP; Lysosomal storage diseases; Lysosome

DOI:  https://doi.org/10.1016/j.ymgme.2023.107729
RSC Med Chem. 2023 Nov 15. 14(11): 2192-2205

Microtubule stabilising peptides: new paradigm towards management of neuronal disorders.

Shubhangi Bhargava, Riya Kulkarni, Bhaskar Dewangan, Neeraj Kulkarni, Chirag Jiaswar, Kunal Kumar, Amit Kumar, Praveen Reddy Bodhe, Hemant Kumar, Bichismita Sahu.

Neuronal cells made of soma, axon, and dendrites are highly compartmentalized and possess a specialized transport system that can convey long-distance electrical signals for the cross-talk. The transport system is made up of microtubule (MT) polymers and MT-binding proteins. MTs play vital and diverse roles in various cellular processes. Therefore, defects and dysregulation of MTs and their binding proteins lead to many neurological disorders as exemplified by Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, and many others. MT-stabilising agents (MSAs) altering the MT-associated protein connections have shown great potential for several neurodegenerative disorders. Peptides are an important class of molecules with high specificity, biocompatibility and are devoid of side effects. In the past, peptides have been explored in various neuronal disorders as therapeutics. Davunetide, a MT-stabilising octapeptide, has entered into phase II clinical trials for schizophrenia. Numerous examples of peptides emerging as MSAs reflect the emergence of a new paradigm for peptides which can be explored further as drug candidates for neuronal disorders. Although small molecule-based MSAs have been reviewed in the past, there is no systematic review in recent years focusing on peptides as MSAs apart from davunetide in 2013. Therefore, a systematic updated review on MT stabilising peptides may shed light on many hidden aspects and enable researchers to develop new therapies for diseases related to the CNS. In this review we have summarised the recent examples of peptides as MSAs.

DOI: https://doi.org/10.1039/d3md00012e
Glia. 2023 Nov 15.

iPSC-derived microglia carrying the TREM2 R47H/+ mutation are proinflammatory and promote synapse loss.

Jay Penney, William T Ralvenius, Anjanet Loon, Oyku Cerit, Vishnu Dileep, Blerta Milo, Ping-Chieh Pao, Hannah Woolf, Li-Huei Tsai.

  Genetic findings have highlighted key roles for microglia in the pathology of neurodegenerative conditions such as Alzheimer's disease (AD). A number of mutations in the microglial protein triggering receptor expressed on myeloid cells 2 (TREM2) have been associated with increased risk for developing AD, most notably the R47H/+ substitution. We employed gene editing and stem cell models to gain insight into the effects of the TREM2 R47H/+ mutation on human-induced pluripotent stem cell-derived microglia. We found transcriptional changes affecting numerous cellular processes, with R47H/+ cells exhibiting a proinflammatory gene expression signature. TREM2 R47H/+ also caused impairments in microglial movement and the uptake of multiple substrates, as well as rendering microglia hyperresponsive to inflammatory stimuli. We developed an in vitro laser-induced injury model in neuron-microglia cocultures, finding an impaired injury response by TREM2 R47H/+ microglia. Furthermore, mouse brains transplanted with TREM2 R47H/+ microglia exhibited reduced synaptic density, with upregulation of multiple complement cascade components in TREM2 R47H/+ microglia suggesting inappropriate synaptic pruning as one potential mechanism. These findings identify a number of potentially detrimental effects of the TREM2 R47H/+ mutation on microglial gene expression and function likely to underlie its association with AD.

Keywords:  Alzheimer's disease; induced pluripotent stem cells; inflammation; microglia; neurodegeneration; triggering receptor expressed on myeloid cells 2 (TREM2)

DOI:  https://doi.org/10.1002/glia.24485
Elife. 2023 Nov 14. pii: RP87081. [Epub ahead of print]12

Human skeletal muscle organoids model fetal myogenesis and sustain uncommitted PAX7 myogenic progenitors.

Lampros Mavrommatis, Hyun-Woo Jeong, Urs Kindler, Gemma Gomez-Giro, Marie-Cecile Kienitz, Martin Stehling, Olympia E Psathaki, Dagmar Zeuschner, M Gabriele Bixel, Dong Han, Gabriela Morosan-Puopolo, Daniela Gerovska, Ji Hun Yang, Jeong Beom Kim, Marcos J Arauzo-Bravo, Jens C Schwamborn, Stephan A Hahn, Ralf H Adams, Hans R Schöler, Matthias Vorgerd, Beate Brand-Saberi, Holm Zaehres.

  In vitro culture systems that structurally model human myogenesis and promote PAX7+ myogenic progenitor maturation have not been established. Here we report that human skeletal muscle organoids can be differentiated from induced pluripotent stem cell lines to contain paraxial mesoderm and neuromesodermal progenitors and develop into organized structures reassembling neural plate border and dermomyotome. Culture conditions instigate neural lineage arrest and promote fetal hypaxial myogenesis toward limb axial anatomical identity, with generation of sustainable uncommitted PAX7 myogenic progenitors and fibroadipogenic (PDGFRa+) progenitor populations equivalent to those from the second trimester of human gestation. Single-cell comparison to human fetal and adult myogenic progenitor /satellite cells reveals distinct molecular signatures for non-dividing myogenic progenitors in activated (CD44High/CD98+/MYOD1+) and dormant (PAX7High/FBN1High/SPRY1High) states. Our approach provides a robust 3D in vitro developmental system for investigating muscle tissue morphogenesis and homeostasis.

Keywords:  Myogenesis; Organoids; Pax7; human; ips cells; regenerative medicine; satellite cells; skeletal muscle; stem cells

DOI:  https://doi.org/10.7554/eLife.87081