MiR-1-mediated repression of V-ATPase subunits is essential for complex assembly and muscle physiology
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ABSTRACT:
ORGANISM(S): Caenorhabditis elegans
PROVIDER: GSE163054 | GEO | 2021/08/06
REPOSITORIES: GEO
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Project description:miR-1-mediated repression of V-ATPase subunits is essential for complex assembly and muscle physiology
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Project description:Muscle function requires unique structural and metabolic adaptations that can render muscle cells selectively vulnerable, with mutations in some ubiquitously expressed genes causing myopathies but sparing other tissues. We uncovered a muscle cell vulnerability by studying miR-1, a deeply conserved, muscle-specific microRNA whose ablation causes various muscle defects. Using Caenorhabditis elegans, we found that miR-1 represses multiple subunits of the ubiquitous vacuolar adenosine triphosphatase (V-ATPase) complex, which is essential for internal compartment acidification and metabolic signaling. V-ATPase subunits are predicted miR-1 targets in animals ranging from C. elegans to humans, and we experimentally validated this in Drosophila. Unexpectedly, up-regulation of V-ATPase subunits upon miR-1 deletion causes reduced V-ATPase function due to defects in complex assembly. These results reveal V-ATPase assembly as a conserved muscle cell vulnerability and support a previously unknown role for microRNAs in the regulation of protein complexes.
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Project description:Muscle function relies on the precise architecture of dynamic contractile elements, which must be fine-tuned to maintain motility throughout life. Muscle is also highly plastic, and remodeled in response to stress, growth, neural and metabolic inputs. The evolutionarily conserved muscle microRNA, mir1, regulates distinct aspects of muscle biology during development, but whether it plays a role during ageing is unknown. Here we investigated the role of C. elegans mir-1 in muscle function in response to proteostatic stress during adulthood. mir-1 deletion results in improved mid-life muscle motility, pharyngeal pumping, and organismal longevity under conditions of polyglutamine repeat proteotoxic challenge. We identified multiple vacuolar ATPase subunits as subject to mir-1 control, and the regulatory subunit vha-13/ATP6VIA as a direct target downregulated via its 3’UTR to mediate mir-1 physiology. mir-1 further regulates nuclear localization of lysosomal biogenesis factor HLH-30/TFEB and lysosomal acidification. Our studies reveal that mir-1 coordinately regulates lysosomal v-ATPase and biogenesis to impact muscle function and health during ageing.
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Project description:BACKGROUND: The eukaryotic cytosolic chaperonin CCT is a hetero-oligomeric complex formed by two rings connected back-to-back, each composed of eight distinct subunits (CCTalpha to CCTzeta). CCT complex mediates the folding, of a wide range of newly synthesised proteins including tubulin (alpha, beta and gamma) and actin, as quantitatively major substrates. METHODOLOGY/PRINCIPAL FINDINGS: We disrupted the genes encoding CCTalpha and CCTdelta subunits in the ciliate Tetrahymena. Cells lacking the zygotic expression of either CCTalpha or CCTdelta showed a loss of cell body microtubules, failed to assemble new cilia and died within 2 cell cycles. We also show that loss of CCT subunit activity leads to axoneme shortening and splaying of tips of axonemal microtubules. An epitope-tagged CCTalpha rescued the gene knockout phenotype and localized primarily to the tips of cilia. A mutation in CCTalpha, G346E, at a residue also present in the related protein implicated in the Bardet Biedel Syndrome, BBS6, also caused defects in cilia and impaired CCTalpha localization in cilia. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that the CCT subunits are essential and required for ciliary assembly and maintenance of axoneme structure, especially at the tips of cilia.
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