The Initiation of Meiotic Sex Chromosome Inactivation Sequesters DNA Damage Signaling from Autosomes in Mouse Spermatogenesis

• Published in: Current biology 2020-02, Vol.30 (3), p.408-420.e5
• Main Authors: Abe, Hironori, Alavattam, Kris G., Hu, Yueh-Chiang, Pang, Qishen, Andreassen, Paul R., Hegde, Rashmi S., Namekawa, Satoshi H.
• Format: Article
• Language: English
• Subjects: Animals; checkpoint; DNA Damage; DNA damage signaling; Dosage Compensation, Genetic; germline; Histones - metabolism; Male; Meiosis; Mice; Phosphorylation; Sex Chromosomes - genetics; Signal Transduction; spermatogenesis; Spermatogenesis - genetics
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2019.11.064

Meiotic sex chromosome inactivation (MSCI) is an essential event in the mammalian male germline. MSCI is directed by a DNA damage response (DDR) pathway centered on the phosphorylation of histone variant H2AX at serine 139 (termed γH2AX). The failure to initiate MSCI is linked to complete meiotic arrest and elimination of germ cells; however, the mechanisms underlying this arrest and elimination remain unknown. To address this question, we established a new separation-of-function mouse model for H2ax that shows specific and complete defects in MSCI. The genetic change is a point mutation in which another H2AX amino acid residue important in the DDR, tyrosine 142 (Y142), is converted to alanine (H2ax-Y142A). In H2ax-Y142A meiosis, the establishment of DDR signals on the chromosome-wide domain of the sex chromosomes is impaired. The initiation of MSCI is required for stage progression, which enables crossover formation, suggesting that the establishment of MSCI permits the timely progression of male meiosis. Our results suggest that normal meiotic progression requires the removal of ATR-mediated DDR signaling from autosomes. We propose a novel biological function for MSCI: the initiation of MSCI sequesters DDR factors from autosomes to the sex chromosomes at the onset of the pachytene stage, and the subsequent formation of an isolated XY nuclear compartment—the XY body—sequesters DDR factors to permit meiotic progression from the mid-pachytene stage onward. [Display omitted] [Display omitted] •The Y142 residue of H2AX is essential for MSCI and XY-body formation•The initial steps of autosomal DSB repair are normal in MSCI-defective mutants•ATR-associated DDR signals are sequestered from autosomes at the onset of MSCI•Novel model for the MSCI checkpoint: MSCI permits meiotic progression Abe et al. demonstrate that tyrosine 142 of histone variant H2AX is required for the initiation of meiotic sex chromosome inactivation (MSCI). Based on new genetic evidence, the study proposes a novel biological function for MSCI: MSCI sequesters DNA damage signaling from autosomes to permit timely progression of male meiosis.