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Melatonin‐induced increase of lipid droplets accumulation and in vitro maturation in porcine oocytes is mediated by mitochondrial quiescence
Author(s) -
He Bin,
Yin Chao,
Gong Yabin,
Liu Jie,
Guo Huiduo,
Zhao Ruqian
Publication year - 2018
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.25876
Subject(s) - melatonin , biology , mitochondrion , mitochondrial dna , oocyte , in vitro maturation , lipid droplet , microbiology and biotechnology , oxidative phosphorylation , tfam , endocrinology , mitochondrial biogenesis , biochemistry , embryo , gene
Melatonin, the major pineal secretory product, has a significant impact on the female reproductive system. Recently, the beneficial effects of melatonin on mammalian oocyte maturation and embryonic development have drawn increased attention. However, the exact underlying mechanisms remain to be fully elucidated. This study demonstrates that supplementing melatonin to in vitro maturation (IVM) medium enhances IVM rate, lipid droplets (LDs) accumulation as well as triglyceride content in porcine oocytes. Decrease of mitochondrial membrane potential, mitochondrial respiratory chain complex IV activity as well as mitochondrial reactive oxygen species (mROS) content indicated that melatonin induced a decrease of mitochondrial activity. The copy number of mitochondrial DNA (mtDNA) which encodes essential subunits of oxidative phosphorylation (OXPHOS), was not affected by melatonin. However, the expression of mtDNA‐encoded genes was significantly down‐regulated after melatonin treatment. The DNA methyltransferase DNMT1, which regulates methylation and expression of mtDNA, was increased and translocated into the mitochondria in melatonin‐treated oocytes. The inhibitory effect of melatonin on the expression of mtDNA was significantly prevented by simultaneous addition of DNMT1 inhibitor, which suggests that melatonin regulates the transcription of mtDNA through up‐regulation of DNMT1 and mtDNA methylation. Increase of triglyceride contents after inhibition of OXPHOS indicated that mitochondrial quiescence is crucial for LDs accumulation in oocytes. Taken together, our results suggest that melatonin‐induced reduction in mROS production and increase in IVM, and LDs accumulation in porcine oocytes is mediated by mitochondrial quiescence.