Research Papers: Pathology:
Mitoguardin-1 and -2 promote maturation and the developmental potential of mouse oocytes by maintaining mitochondrial dynamics and functions
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Xiao-Man Liu1, Yong-Ping Zhang1, Shu-Yan Ji1, Bo-Tai Li1, Xuejun Tian1, Dali Li2, Chao Tong1 and Heng-Yu Fan1
1 Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, China
2 Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
Heng-Yu Fan, email:
Chao Tong, email:
Keywords: mitochondrion, ROS, mtDNA copy number, oocyte meiosis, female infertility, Pathology Section
Received: October 02, 2015 Accepted: December 09, 2015 Published: December 21, 2015
Mitochondrial dynamics change mitochondrial morphological features and numbers as a part of adaptive cellular metabolism, which is vital for most eukaryotic cells and organisms. A disease or even death of an animal can occur if these dynamics are disrupted. Using large-scale genetic screening in fruit flies, we previously found the gene mitoguardin (Miga), which encodes a mitochondrial outer-membrane protein and promotes mitochondrial fusion. Knockout mouse strains were generated for the mammalian Miga homologs Miga1 and Miga2. Miga1/2-/- females show greatly reduced quality of oocytes and early embryos and are subfertile. Mitochondria became clustered in the cytoplasm of oocytes from the germinal-vesicle stage to meiosis II; production of reactive oxygen species increased in mitochondria and caused damage to mitochondrial ultrastructures. Additionally, reduced ATP production, a decreased mitochondrial-DNA copy number, and lower mitochondrial membrane potential were detected in Miga1/2-/- oocytes during meiotic maturation. These changes resulted in low rates of polar-body extrusion during oocyte maturation, reduced developmental potential of the resulting early embryos, and consequently female subfertility. We provide direct evidence that MIGA1/2-regulated mitochondrial dynamics is crucial for mitochondrial functions, ensure oocyte maturation, and maintain the developmental potential.
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