[Evolution of mammalian sex chromosomes: cooperation of genetic and epigenetic factors].
The X and Y chromosomes of mammals, which significantly differ in structure and genetic composition, are thought to originate from a pair of autosomes. During evolution of sex chromosomes in placental mammals, the degradation of the Y chromosome and inactivation spreading along the X chromosome occurred gradually and in concert. Thus, at the molecular level, the genetic and epigenetic factors interacted toward greater differentiation of the X/Y pair. In this review, in context of a comparison permitting to trace this evolutionary pathway, we consider the structural features of mammalian sex chromosomes focusing on the X-chromosomal genes and the unique epigenetic mechanism of their regulation. Possible causes and consequences of the genes skipping inactivation and aspects of molecular mechanism of X-chromosome inactivation are discussed. A number of hypotheses are considered on evolutionary relationships of X-chromosome inactivation and other molecular processes in mammals.
Anoprienko
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Zakiian
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D000818:Animals; D005075:Biological Evolution; D044127:Epigenesis, Genetic; D008322:Mammals / Q000235:genetics*; D012730:Sex Chromosomes