Meiotic sex chromosome inactivation

TLDR

X‑chromosome inactivation occurs in male germ cells during meiosis, a process termed meiotic sex chromosome inactivation (MSCI) that serves as a model for epigenetic regulation of gene expression. MSCI is a specific instance of meiotic silencing of unsynapsed chromatin (MSUC), which silences unpaired chromosomes to prevent aneuploidy, and its failure is linked to meiotic sterility.

Abstract

X chromosome inactivation is most commonly studied in the context of female mammalian development, where it performs an essential role in dosage compensation. However, another form of X-inactivation takes place in the male,during spermatogenesis, as germ cells enter meiosis. This second form of X-inactivation, called meiotic sex chromosome inactivation (MSCI) has emerged as a novel paradigm for studying the epigenetic regulation of gene expression. New studies have revealed that MSCI is a special example of a more general mechanism called meiotic silencing of unsynapsed chromatin (MSUC), which silences chromosomes that fail to pair with their homologous partners and, in doing so, may protect against aneuploidy in subsequent generations. Furthermore, failure in MSCI is emerging as an important etiological factor in meiotic sterility.