Inflammation causes remodeling of mitochondrial cytochrome <i>c</i> oxidase mediated by the bifunctional gene <i>C15orf48</i>.

Clayton, Sally A; Daley, Kalbinder K; MacDonald, Lucy; Fernandez-Vizarra, Erika; Bottegoni, Giovanni; O'Neil, John D; Major, Triin; Griffin, Daniel et al. · Sci Adv · 2021

basic_science · Level V

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Abstract

Dysregulated mitochondrial function is a hallmark of immune-mediated inflammatory diseases. Cytochrome <i>c</i> oxidase (C<i>c</i>O), which mediates the rate-limiting step in mitochondrial respiration, is remodeled during development and in response to changes of oxygen availability, but there has been little study of C<i>c</i>O remodeling during inflammation. Here, we describe an elegant molecular switch mediated by the bifunctional transcript <i>C15orf48</i>, which orchestrates the substitution of the C<i>c</i>O subunit NDUFA4 by its paralog C15ORF48 in primary macrophages. Expression of <i>C15orf48</i> is a conserved response to inflammatory signals and occurs in many immune-related pathologies. In rheumatoid arthritis, <i>C15orf48</i> mRNA is elevated in peripheral monocytes and proinflammatory synovial tissue macrophages, and its expression positively correlates with disease severity and declines in remission. <i>C15orf48</i> is also expressed by pathogenic macrophages in severe coronavirus disease 2019 (COVID-19). Study of a rare metabolic disease syndrome provides evidence that loss of the NDUFA4 subunit supports proinflammatory macrophage functions.