RESUMEN
Oocyte activation deficiency leads to female infertility. [Ca2+ ]i oscillations are required for mitochondrial energy supplement transition from the resting to the excited state, but the underlying mechanisms are still very little known. Three mitochondrial Ca2+ channels, Mitochondria Calcium Uniporter (MCU), Na+ /Ca2+ Exchanger (NCLX) and Voltage-dependent Ca2+ Channel (VDAC), were deactivated by inhibitors RU360, CGP37157 and Erastin, respectively. Both Erastin and CGP37157 inhibited mitochondrial activity significantly while attenuating [Ca2+ ]i and [Ca2+ ]m oscillations, which caused developmental block of pronuclear formation. Thus, NCLX and VDAC are two mitochondria-associated Ca2+ transporter proteins regulating oocyte activation, which may be used as potential targets to treat female infertility. SIGNIFICANCE OF THE STUDY: NCLX and VDAC are two mitochondria-associated Ca2+ transporter proteins regulating oocyte activation.
Asunto(s)
Canales de Calcio/metabolismo , Calcio/metabolismo , Oocitos/metabolismo , Animales , Canales de Calcio/química , Femenino , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones , Ratones Endogámicos ICR , Mitocondrias/metabolismo , Oocitos/citología , Oocitos/efectos de los fármacos , Compuestos de Rutenio/farmacología , Rojo de Rutenio/farmacología , Intercambiador de Sodio-Calcio/antagonistas & inhibidores , Intercambiador de Sodio-Calcio/metabolismo , Tiazepinas/farmacología , Canales Aniónicos Dependientes del Voltaje/antagonistas & inhibidores , Canales Aniónicos Dependientes del Voltaje/metabolismoRESUMEN
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.