ATR acts stage specifically to regulate multiple aspects of mammalian meiotic silencing

Genes Dev. 2013 Jul 1;27(13):1484-94. doi: 10.1101/gad.219477.113.

Abstract

In mammals, homologs that fail to synapse during meiosis are transcriptionally inactivated. This process, meiotic silencing, drives inactivation of the heterologous XY bivalent in male germ cells (meiotic sex chromosome inactivation [MSCI]) and is thought to act as a meiotic surveillance mechanism. The checkpoint protein ATM and Rad3-related (ATR) localizes to unsynapsed chromosomes, but its role in the initiation and maintenance of meiotic silencing is unknown. Here we show that ATR has multiple roles in silencing. ATR first regulates HORMA (Hop1, Rev7, and Mad2) domain protein HORMAD1/2 phosphorylation and localization of breast cancer I (BRCA1) and ATR cofactors ATR-interacting peptide (ATRIP)/topoisomerase 2-binding protein 1 (TOPBP1) at unsynapsed axes. Later, it acts as an adaptor, transducing signaling at unsynapsed axes into surrounding chromatin in a manner that requires interdependence with mediator of DNA damage checkpoint 1 (MDC1) and H2AFX. Finally, ATR catalyzes histone H2AFX phosphorylation, the epigenetic event leading to gene inactivation. Using a novel genetic strategy in which MSCI is used to silence a chosen gene in pachytene, we show that ATR depletion does not disrupt the maintenance of silencing and that silencing comprises two phases: The first is dynamic and reversible, and the second is stable and irreversible. Our work identifies a role for ATR in the epigenetic regulation of gene expression and presents a new technique for ablating gene function in the germline.

Keywords: ATR; meiosis; sex chromosomes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism*
  • Chromosomes / metabolism
  • Gene Expression Regulation*
  • Gene Silencing*
  • Histones / metabolism
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Male
  • Meiosis*
  • Mice
  • Phosphorylation
  • Protein Transport / genetics
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Repressor Proteins / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • H2AX protein, mouse
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • MDC1 protein, mouse
  • Repressor Proteins
  • Atr protein, mouse
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases