Research Progress in the Activity of X Chromosome in Mammalian Primordial Germ Cells
YUAN Wenjing, ZHANG Yuting, LIU Zhonghua, WENG Xiaogang*
PGCs (primordial germ cells) are the first germ cell populations produced during embryonic development, originating from gastrula stage. PGCs undergoe four stages of development: specialization, migration, proliferation and differentiation, ultimately giving rise to either sperm or oocytes. In female Eutheria, XCI (X chromosome inactivation) occurs to compensate for the sex chromosome difference between females (XX) and males (XY). During mammalian development, the X chromosome activity in PGCs is dynamically regulated, with the inactivated XCR (X chromosome reactivation) after specialization. This process involves a series epigenetic reprogramming events, such as the histone modifications erasure, DNA demethylation, and chromatin structure remodeling. X chromosome reactivation is crucial for PGCs differentiation and the production of functional gametes. Abnormal X chromosome activity will seriously affect the differentiation of PGCs. This review focuses on the changing pattern of X chromosome activity during PGCs development, the regulatory factors of X chromosome activity, the mechanism of XCR, and compare the differences of PGCs X chromosome activity changes across various species.
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