AUTHOR=Wang Feng , Meng Tie-Gang , Li Jian , Hou Yi , Luo Shi-Ming , Schatten Heide , Sun Qing-Yuan , Ou Xiang-Hong TITLE=Mitochondrial Ca2 + Is Related to Mitochondrial Activity and Dynamic Events in Mouse Oocytes JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=8 YEAR=2020 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2020.585932 DOI=10.3389/fcell.2020.585932 ISSN=2296-634X ABSTRACT=

Mitochondrial energy insufficiency is strongly associated with oocyte activation disorders. Ca2+, especially that in the mitochondrial matrix, plays a pivotal role in mitochondrial energy supplementation, but the underlying mechanisms are still only poorly understood. An encoded mitochondrial matrix Ca2+ probe (Mt-GCaMP6s) was introduced to observe mitochondrial Ca2+ ([Ca2+]m) dynamic changes during oocyte maturation and activation. We found that active mitochondria surrounding the nucleus showed a higher [Ca2+]m than those distributed in the cortex during oocyte maturation. During oocyte partheno-activation, the patterns of Ca2+ dynamic changes were synchronous in the cytoplasm and mitochondria. Such higher concentration of mitochondrial matrix Ca2+ was closely related to the distribution of mitochondrial calcium uptake (MICU) protein. We further showed that higher [Ca2+]m mitochondria around the chromosomes in oocytes might have a potential role in stimulating mitochondrial energy for calmodulin-responsive oocyte spindle formation, while synchronizing Ca2+ functions in the cytoplasm and nuclear area are important for oocyte activation.