title: The great escape: Active genes on inactive sex chromosomes and their evolutionary implications.
abstract: Epigenetic mechanisms precisely regulate sex chromosome inactivation as well as genes that escape the silencing process. In male germ cells, DNA damage response factor RNF8 establishes active epigenetic modifications on the silent sex chromosomes during meiosis, and activates escape genes during a state of sex chromosome-wide silencing in postmeiotic spermatids. During the course of evolution, the gene content of escape genes in postmeiotic spermatids recently diverged on the sex chromosomes. This evolutionary feature mirrors the epigenetic processes of sex chromosomes in germ cells. In this article, we describe how epigenetic processes have helped to shape the evolution of sex chromosome-linked genes. Furthermore, we compare features of escape genes on sex chromosomes in male germ cells to escape genes located on the single X chromosome silenced during X-inactivation in females, clarifying the distinct evolutionary implications between male and female escape genes.
authors.affiliation: Division of Reproductive Sciences; Division of Developmental Biology; Perinatal Institute; Cincinnati Children's Hospital Medical Center; Cincinnati, OH USA; Department of Pediatrics; University of Cincinnati College of Medicine; Cincinnati, OH USA.
authors.forename: Ho-Su
authors.initials: HS
authors.lastname: Sin
authors.forename: Satoshi H
authors.initials: SH
authors.lastname: Namekawa
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D044127:Epigenesis, Genetic; D019143:Evolution, Molecular; D005260:Female; D050172:Genes, X-Linked; D050173:Genes, Y-Linked; D016678:Genome; D005854:Germ Cells / Q000378:metabolism; D006801:Humans; D008297:Male; D008540:Meiosis; D005810:Multigene Family; D010802:Phylogeny; D012730:Sex Chromosomes; D013087:Spermatids; D049951:X Chromosome Inactivation
chemical_list: D004268:DNA-Binding Proteins
keywords: DNA damage response; escape genes; evolution; meiosis; sex chromosomes