Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 115, Issue 34, Pages E7960-E7969Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1807811115
Keywords
neurodegeneration; calcium; manganese; EF hand; selectivity
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Funding
- National Institutes of Health [R01HL130143, R00HL124070]
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [R00HL124070, R01HL130143, R01HL141353] Funding Source: NIH RePORTER
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The mitochondrial uniporter is a Ca2+-activated Ca2+ channel complex that displays exceptionally high conductance and selectivity. Here, we report cellular metal toxicity screens highlighting the uniporter's role in Mn2+ toxicity. Cells lacking the pore-forming uniporter subunit, MCU, are more resistant to Mn2+ toxicity, while cells lacking the Ca2+-sensing inhibitory subunit, MICU1, are more sensitive than the wild type. Consistent with these findings, Caenorhabditis elegans lacking the uniporter's pore have increased resistance to Mn2+ toxicity. The chemical-genetic interaction between uniporter machinery and Mn2+ toxicity prompted us to hypothesize that Mn2+ can indeed be transported by the uniporter's pore, but this transport is prevented by MICU1. To this end, we demonstrate that, in the absence of MICU1, both Mn2+ and Ca2+ can pass through the uniporter, as evidenced by mitochondrial Mn2+ uptake assays, mitochondrial membrane potential measurements, and mitoplast electrophysiology. We show that Mn2+ does not elicit the conformational change in MICU1 that is physiologically elicited by Ca2+, preventing Mn2+ from inducing the pore opening. Our work showcases a mechanism by which a channel's auxiliary subunit can contribute to its apparent selectivity and, furthermore, may have implications for understanding how manganese contributes to neurodegenerative disease.
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