Search

Mutations in the nuclear-encoded mitochondrial gene CHCHD10 have been observed in patients with a spectrum of diseases that include amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). To investigate the pathogenic nature of disease-associated variants of CHCHD10 we generated a zebrafish knock-in (KI) model expressing the orthologous ALS-associated CHCHD10 P80L variant (zebrafish: Chchd10 P83L ). Larval chchd10 P83L/P83L fish displayed reduced Chchd10 protein expression levels, motor impairment, reduced survival and abnormal neuromuscular junctions (NMJ). These deficits were not accompanied by changes in transcripts involved in the integrated stress response (ISR), phenocopying previous findings in our knockout (chchd10 -/- ). Adult, 11-month old chchd10 P83L/P83L zebrafish, displayed smaller slow- and fast-twitch muscle cell cross-sectional areas compared to wild type zebrafish muscle cells. Motoneurons in the spinal cord of chchd10 P83L/P83L zebrafish displayed similar cross-sectional areas to that of wild type motor neurons and significantly fewer motor neurons were observed when compared to chchd2 -/- adult spinal cords. Bulk RNA sequencing using whole spinal cords of 7-month old fish revealed transcriptional changes associated with neuroinflammation, apoptosis, amino acid metabolism and mt-DNA inflammatory response in our chchd10 P83L/P83L model. The findings presented here, suggest that the CHCHD10 P80L variant confers an ALS-like phenotype when expressed in zebrafish., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Mutations in CHCHD10 and CHCHD2, encoding two paralogous mitochondrial proteins, have been identified in cases of amyotrophic lateral sclerosis, frontotemporal lobar degeneration, and Parkinson's disease. Their role in disease is unclear, though both have been linked to mitochondrial respiration and mitochondrial stress responses. Here, we investigated the biological roles of these proteins during vertebrate development using knockout (KO) models in zebrafish. We demonstrate that loss of either or both proteins leads to motor impairment, reduced survival and compromised neuromuscular junction integrity in larval zebrafish. Compensation by Chchd10 was observed in the chchd2 -/- model, but not by Chchd2 in the chchd10 -/- model. The assembly of mitochondrial respiratory chain Complex I was impaired in chchd10 -/- and chchd2 -/- zebrafish larvae, but unexpectedly not in a double chchd10 -/- and chchd2 -/- model, suggesting that reduced mitochondrial Complex I cannot be solely responsible for the observed phenotypes, which are generally more severe in the double KO. We observed transcriptional activation markers of the mitochondrial integrated stress response (mt-ISR) in the double chchd10 -/- and chchd2 -/- KO model, suggesting that this pathway is involved in the restoration of Complex I assembly in our double KO model. The data presented here demonstrates that the Complex I assembly defect in our single KO models arises independently of the mt-ISR. Furthermore, this study provides evidence that both proteins are required for normal vertebrate development., (© 2023 The Authors. Developmental Neurobiology published by Wiley Periodicals LLC.)

This article examines how white British residents of a superdiverse London housing estate learn about-and subsequently deploy-the intra-ethnic stereotypes used by their British Pakistani and British Bangladeshi neighbours/flatmates. Building on recent attempts to bring together conviviality and boundary making, along with insights into intra-ethnic othering, we show how, for white British residents, these stereotypes offered the chance to add detail and authenticity to judgements about the "unrespectable" behaviour of British Asian residents and/or visitors. Ultimately, however, white British residents' inappropriate and/or imprecise deployment of these stereotypes in relation to British Bangladeshis and British Pakistanis led to the misidentification of low-status people and the unfair extension of discrimination faced by low-status individuals and families. Furthermore, the combination of clumsy application and the positioning of "respectable" British Bangladeshis and British Pakistanis as purveyors of "insider knowledge" about intra-ethnic stereotypes led to the reinscribing of boundaries between racial groups. We conclude that studying the cross-racial use of intra-ethnic stereotypes allows for a subtler appreciation of the complex dynamics of inclusion and exclusion in superdiverse areas., (© 2022 The Authors. The British Journal of Sociology published by John Wiley & Sons Ltd on behalf of London School of Economics and Political Science.)

Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disorder in which the neuromuscular junction progressively degenerates, leading to movement difficulties, paralysis, and eventually death. ALS is currently being treated by only two FDA-approved drugs with modest efficacy in slowing disease progression. Often, the translation of preclinical findings to bedside terminates prematurely as the evaluation of potential therapeutic compounds focuses on a single study or a single animal model. To circumscribe these issues, we screened 3,765 novel small molecule derivatives of pimozide, a recently identified repurposed neuroleptic for ALS, in Caenorhabditis elegans, confirmed the hits in zebrafish and validated the most active compounds in mouse genetic models. Out of the 27 small molecules identified from the high-throughput screen in worms, 4 were found to recover locomotor defects in C. elegans and genetic zebrafish models of ALS. TRVA242 was identified as the most potent compound as it significantly improved efficiency in rescuing locomotor, motorneuron, and neuromuscular junction synaptic deficits in a C. elegans TDP-43 model and in multiple zebrafish genetic (TDP-43, SOD1, and C9ORF72) models of ALS. The actions of TRVA242 were also conserved in a mammalian model as it also stabilized neuromuscular junction deficits in a mouse SOD1 model of ALS. Compounds such as TRVA242 therefore represent new potential therapeutics for the treatment of ALS.

Almost 90% of amyotrophic lateral sclerosis (ALS) cases are characterized by the presence of aggregates of insoluble, misfolded cytoplasmic TAR DNA binding protein of 43 kDa (TDP-43). Distal axonopathy with impaired neuromuscular junctions (NMJs) before motor neuron degeneration or clinical onset of symptoms has been hypothesized as an early pathology in ALS. However, synaptic defects at the NMJ caused by TDP-43 mutations have not been characterized. In this study, we examined a previously reported zebrafish line expressing the tardbp Y220X/Y220X variant, which results in an unstable and degraded protein. These tardbp -/- larvae, however, mature normally due to the upregulated expression of an alternative splice variant of the tardbp paralog tardbp-like, or tardbpl. We generated a mutant line with a CRISPR/Cas9-mediated 5-base pair deletion encompassing the ATG start codon of tardbpl and in-crossed these with tardbp -/- mutants to obtain tardbp -/- and tardbpl -/- double mutants, herein referred to as hom/hom. We subsequently characterized morphological, coiling, locomotor, synaptic, and NMJ structural abnormalities in the hom/hom mutants and in their genotypic controls. We observed that hom/hom mutants displayed gross morphological defects, early lethality, reduced locomotor function, aberrant quantal transmission, and perturbed synapse architecture at the NMJ. We further employed pharmacological manipulations in an effort to rescue phenotypic defects and observed that tardbp +/- ; tardbpl -/- (herein referred to as het/hom) mutants, but not hom/hom mutants, were sensitive to chronic treatments of BAY K 8644, an L-type calcium channel agonist. This result highlights the importance of partial vs. complete loss of allelic functions of TDP-43. NEW & NOTEWORTHY This study highlights the importance of partial vs. complete loss of allelic functions of TDP-43 in a zebrafish loss of function model, thus making it an attractive tool for drug screening approaches.

Amyotrophic lateral sclerosis (ALS) presents clinically in adulthood and is characterized by the loss of motoneurons in the spinal cord and cerebral cortex. Animal models of the disease suggest that significant neuronal abnormalities exist during preclinical stages of the disease. Mutations in the gene fused in sarcoma (FUS) are associated with ALS and cause impairment in motor function in animal models. However, the mechanism of neuromuscular dysfunction underlying pathophysiological deficits causing impairment in locomotor function resulting from mutant FUS expression is unknown. To characterize the cellular pathophysiological defect, we expressed the wild-type human gene (wtFUS) or the ALS-associated mutation R521H (mutFUS) gene in zebrafish larvae and characterized their motor (swimming) activity and function of their neuromuscular junctions (NMJs). Additionally, we tested knockdown of zebrafish fus with an antisense morpholino oligonucleotide (fus AMO). Expression of either mutFUS or knockdown of fus resulted in impaired motor activity and reduced NMJ synaptic fidelity with reduced quantal transmission. Primary motoneurons expressing mutFUS were found to be more excitable. These impairments in neuronal function could be partially restored in fus AMO larvae also expressing wtFUS (fus AMO+wtFUS) but not mutFUS (fus AMO+mutFUS). These results show that both a loss and gain of FUS function result in defective presynaptic function at the NMJ.