Mitoguardin 1 and 2 promote granulosa cell proliferation by activating AKT and regulating the Hippo-YAP1 signaling pathway

Abstract

Mitochondria have been identified to be involved in oxidative phosphorylation, lipid metabolism, cell death, and cell proliferation. Previous studies have demonstrated that mitoguardin (Miga), a mitochondrial protein that governs mitochondrial fusion, mitochondria-endoplasmic reticulum (ER) contacts, lipid formation, and autophagy, is crucial for ovarian endocrine and follicular development. Nevertheless, whether mammalian MIGA1 or MIGA2 (MIGA1,-2) regulates ovarian granulosa cell proliferation remains unclear. This study revealed that mammalian MIGA1,-2 promotes cell proliferation and regulates the phosphorylation and localization of Yes-associated protein 1 (YAP1) in ovarian granulosa cells. MIGA2 upregulation resulted in reduced YAP1 activity, while MIGA2 removal led to increased YAP1 activity. Further analysis indicated that MIGA1,-2 regulated YAP1 via the Hippo signaling pathway and regulated protein kinase B (AKT) activity in collaboration with YAP1. In addition, lysophosphatidic acid (LPA) regulated MIGA2 expression and AKT activity by activating YAP1. Briefly, we demonstrated that the mitochondrial MIGA1 and MIGA2, especially MIGA2, promoted cellular proliferation by activating AKT and regulating the Hippo/YAP1 signaling pathway in ovarian granulosa cells, which may contribute to the molecular pathogenesis of reproductive endocrine diseases, such as polycystic ovary syndrome (PCOS).