Lessons from comparative analysis of X-chromosome inactivation in mammals.
In most mammals, X-chromosome inactivation is used as the strategy to achieve dosage compensation between XX females and XY males. This process is developmentally regulated, resulting in the differential treatment of the two X chromosomes in the same nucleus and mitotic heritability of the silent state. A lack of dosage compensation in an XX embryo is believed to result in early lethality, at least in eutherians. Given its fundamental importance, X-chromosome inactivation would be predicted to be a highly conserved process in mammals. However, recent studies have revealed major mechanistic differences in X inactivation between eutherians and marsupials, suggesting that the evolution of the X chromosome as well as developmental differences between mammals have led to diverse evolutionary strategies for dosage compensation.
Okamoto
Ikuhiro
I
Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR3215 INSERM U934, 26 rue d'Ulm, 75248 Paris Cedex 05, France. ikuhiro.Okamoto@curie.fr
Heard
Edith
E
D000818:Animals; D005075:Biological Evolution; D044127:Epigenesis, Genetic; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008322:Mammals / Q000235:genetics*; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics; D049951:X Chromosome Inactivation
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; C077885:XIST non-coding RNA