The Mouse X Chromosome Is Enriched for Multicopy Testis Genes Showing Postmeiotic Expression

Nat Genet. 2008 Jun;40(6):794-9. doi: 10.1038/ng.126. Epub 2008 May 4.

Abstract

According to the prevailing view, mammalian X chromosomes are enriched in spermatogenesis genes expressed before meiosis and deficient in spermatogenesis genes expressed after meiosis. The paucity of postmeiotic genes on the X chromosome has been interpreted as a consequence of meiotic sex chromosome inactivation (MSCI)--the complete silencing of genes on the XY bivalent at meiotic prophase. Recent studies have concluded that MSCI-initiated silencing persists beyond meiosis and that most genes on the X chromosome remain repressed in round spermatids. Here, we report that 33 multicopy gene families, representing approximately 273 mouse X-linked genes, are expressed in the testis and that this expression is predominantly in postmeiotic cells. RNA FISH and microarray analysis show that the maintenance of X chromosome postmeiotic repression is incomplete. Furthermore, X-linked multicopy genes exhibit a similar degree of expression as autosomal genes. Thus, not only is the mouse X chromosome enriched for spermatogenesis genes functioning before meiosis, but in addition, approximately 18% of mouse X-linked genes are expressed in postmeiotic cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • DNA Probes
  • Gene Dosage
  • Gene Expression Regulation, Developmental*
  • Genes, X-Linked / genetics*
  • In Situ Hybridization, Fluorescence
  • Male
  • Meiosis / genetics
  • Mice
  • Oligonucleotide Array Sequence Analysis
  • RNA Probes
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spermatogenesis / genetics*
  • Spermatozoa / metabolism*
  • Testis / physiology*
  • X Chromosome / genetics*

Substances

  • DNA Probes
  • RNA Probes
  • RNA, Messenger