Biology subjects

Battersby, B. J.

Publications and source records attributed to Battersby, B. J..

4 recordsLinked to original sources

bioRxiv2025

Intrinsic errors in mitochondrial translation trigger a decline in cell fitness.

Defects in the faithful expression of the human mitochondrial genome underlies disease states, from rare inherited disorders to common pathologies and the aging process itself. The ensuing decrease in the capacity for oxidative phosphorylation alone cannot account for the phenotype complexity associated with disease. Here, we address how aberrations in mitochondrial nascent chain synthesis per se exert a decline in cell fitness using a classic model of mitochondrial induced premature aging. We identify how intrinsic errors during mitochondrial nascent chain synthesis destabilize organelle gene expression, triggering intracellular stress responses that rewire cellular metabolism and cytokine secretion. Further, we show how these mechanisms extend to pathogenic variants associated with inherited human disorders. Together, our findings reveal how aberrations in mitochondrial protein synthesis can sensitize a cell to metabolic challenges associated with disease and pathogen infection independent of oxidative phosphorylation. Teaser/One-Sentence SummaryAberrations in mitochondrial translation elongation trigger activation of intracellular stress responses associated with disease and aging.

cell biology↗

bioRxiv2022

Supernumerary proteins of the human mitochondrial ribosomal small subunit are integral for assembly and translation

Mitochondrial ribosomes (mitoribosomes) have undergone substantial structural remodelling throughout evolution. Compared to their prokaryotic counterparts, mitoribosomes show a substantial loss of ribosomal RNA, whilst acquiring unique protein subunits located on the periphery of the ribosomal subunit structures. We set out to investigate the functional properties of all 14 unique (mitochondrial-specific or supernumerary) human mitoribosomal proteins in the small subunit. Using genome editing with CRISPR-Cas9, we made knockouts for each subunit in HEK293 cells to study the effect on mitoribosome assembly and function in protein synthesis. Unexpectedly, we show that each supernumerary knockout leads to a unique mitoribosome assembly defect with variable impact on mitochondrial protein synthesis. Our data demonstrates that all supernumerary subunits are essential structural components except mS37. Surprisingly, we found the stability of mS37 was reduced in all our supernumerary knockouts of the small and large ribosomal subunits as well as patient-derived lines with mitoribosome assembly defects. We identified that a redox regulated CX9C motif in mS37 was essential for protein stability, suggesting a potential mechanism to regulate mitochondrial protein synthesis. Together, our findings support a modular assembly of the human mitochondrial small ribosomal subunit mediated by essential supernumerary subunits and identify a redox regulatory role involving mS37 in mitochondrial protein synthesis in health and disease.

molecular biology↗

bioRxiv2021

Mitochondrial dysfunction triggers secretion of the immunosuppressive factor α-fetoprotein

Signaling circuits crucial to systemic physiology are widespread, yet uncovering their molecular underpinnings remains a barrier to understanding the etiology of many metabolic disorders. Here, we identify a copper-linked signaling circuit activated by disruption of mitochondrial function in the murine liver or heart that results in atrophy of the spleen and thymus and causes a peripheral white blood cell deficiency. We demonstrate that the leukopenia is caused by -fetoprotein, which requires copper and the cell surface receptor CCR5 to promote white blood cell death. We further show that -fetoprotein expression is upregulated in several cell types upon inhibition of oxidative phosphorylation, including a muscle cell model of Barth syndrome. Collectively, our data argue that -fetoprotein secreted by bioenergetically stressed tissue suppresses the immune system, an effect which may explain the recurrent infections that are observed in a subset of mitochondrial diseases or in other disorders with mitochondrial involvement.

cell biology↗

bioRxiv2018

Mice harboring a SCA28 patient mutation in AFG3L2 develop late-onset ataxia associated with enhanced mitochondrial proteotoxicity.

Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but signs of ataxia were detectable by beam test at 18 months. Cerebellar pathology was negative; electrophysiological analysis showed increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls, although not statistically significant. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was also altered, in line with greatly reduced expression of Opa1 fusogenic protein L-isoforms. The mitochondrial alterations observed in MEFs were also detected in cerebella of 18-month-old heterozygous mutants, suggesting they may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.

genetics↗