Regulation of Interorganellar Ca2+ Transfer and NFAT Activation by the Mitochondrial Ca2+ Uniporter

Yoast, R. E.; Emrich, S. M.; Zhang, X.; Xin, P.; Arige, V.; Pathak, T.; Benson, J. C.; Johnson, M. T.; Lakomski, N.; Hempel, N.; Han, J. M.; Dupont, G.; Yule, D. I.; Sneyd, J.; Trebak, M.

doi:10.1101/2021.04.07.438854

bioRxiv · 10.1101/2021.04.07.438854

Regulation of Interorganellar Ca2+ Transfer and NFAT Activation by the Mitochondrial Ca2+ Uniporter

Yoast, R. E.·Emrich, S. M.·Zhang, X.·Xin, P.·Arige, V.·Pathak, T.·Benson, J. C.·Johnson, M. T.·Lakomski, N.·Hempel, N.·Han, J. M.·Dupont, G.·Yule, D. I.·Sneyd, J.·Trebak, M.

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Abstract

Mitochondrial Ca2+ uptake is crucial for coupling receptor stimulation to cellular bioenergetics. Further, Ca2+ uptake by respiring mitochondria prevents Ca2+-dependent inactivation (CDI) of store-operated Ca2+ release-activated Ca2+ (CRAC) channels and inhibits Ca2+ extrusion to sustain cytosolic Ca2+ signaling. However, how Ca2+ uptake by the mitochondrial Ca2+ uniporter (MCU) shapes receptor-evoked interorganellar Ca2+ signaling is unknown. Here, we generated several cell lines with MCU-knockout (MCU-KO) as well as tissue-specific MCU-knockdown mice. We show that mitochondrial depolarization, but not MCU-KO, inhibits store-operated Ca2+ entry (SOCE). Paradoxically, despite enhancing Ca2+ extrusion and promoting CRAC channel CDI, MCU-KO increased cytosolic Ca2+ in response to store depletion. Further, physiological agonist stimulation in MCU-KO cells led to enhanced frequency of cytosolic Ca2+ oscillations, endoplasmic reticulum Ca2+ refilling, NFAT nuclear translocation and proliferation. However, MCU-KO did not affect inositol-1,4,5-trisphosphate receptor activity. Mathematical modeling supports that MCU-KO enhances cytosolic Ca2+, despite limiting CRAC channel activity.

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Yoast, R. E., Emrich, S. M., Zhang, X., Xin, P., Arige, V., Pathak, T., Benson, J. C., Johnson, M. T., Lakomski, N., Hempel, N., Han, J. M., Dupont, G., Yule, D. I., Sneyd, J., Trebak, M.. 2021-04-07. Regulation of Interorganellar Ca2+ Transfer and NFAT Activation by the Mitochondrial Ca2+ Uniporter. https://doi.org/10.1101/2021.04.07.438854

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