An essential role for cardiolipin in the stability and function of the mitochondrial calcium uniporter

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 28; pp. 16383 - 16390
• Main Authors: Ghosh, Sagnika, Ball, Writoban Basu, Madaris, Travis R., Srikantan, Subramanya, Madesh, Muniswamy, Mootha, Vamsi K., Gohil, Vishal M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 14.07.2020
• Subjects: Animals; Barth Syndrome - genetics; Barth Syndrome - metabolism; Bioenergetics; Biological Sciences; Biological Transport; Biosynthesis; Calcium; Calcium (mitochondrial); Calcium - metabolism; Calcium Channels - chemistry; Calcium Channels - genetics; Calcium Channels - metabolism; Calcium influx; Calcium signalling; Calcium transport; Cardiolipin; Cardiolipins - genetics; Cardiolipins - metabolism; Homology; Humans; Ion channels; Lecithin; Lipids; Mice; Mitochondria; Mitochondria - chemistry; Mitochondria - genetics; Mitochondria - metabolism; Mutants; Myoblasts - metabolism; Pathogenesis; Phosphatidylcholine; Phosphatidylethanolamine; Phospholipids; Pore formation; Protein Stability; Saccharomyces cerevisiae - chemistry; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Stability; Yeast; Barth syndrome; EMRE; mitochondrial calcium uniporter (MCU); uniplex; cardiolipin
• DOI: 10.1073/pnas.2000640117
• ISSN: 0027-8424; 1091-6490

Calcium uptake by the mitochondrial calcium uniporter coordinates cytosolic signaling events with mitochondrial bioenergetics. During the past decade all protein components of the mitochondrial calcium uniporter have been identified, including MCU, the pore-forming subunit. However, the specific lipid requirements, if any, for the function and formation of this channel complex are currently not known. Here we utilize yeast, which lacks the mitochondrial calcium uniporter, as a model system to address this problem. We use heterologous expression to functionally reconstitute human uniporter machinery both in wild-type yeast as well as in mutants defective in the biosynthesis of phosphatidylethanolamine, phosphatidylcholine, or cardiolipin (CL). We uncover a specific requirement of CL for in vivo reconstituted MCU stability and activity. The CL requirement of MCU is evolutionarily conserved with loss of CL triggering rapid turnover of MCU homologs and impaired calcium transport. Furthermore, we observe reduced abundance and activity of endogenous MCU in mammalian cellular models of Barth syndrome, which is characterized by a partial loss of CL. MCU abundance is also decreased in the cardiac tissue of Barth syndrome patients. Our work raises the hypothesis that impaired mitochondrial calcium transport contributes to the pathogenesis of Barth syndrome, and more generally, showcases the utility of yeast phospholipid mutants in dissecting the phospholipid requirements of ion channel complexes.