Do LINEs Have a Role in X-Chromosome Inactivation?

[摘要] There is longstanding evidence that X-chromosome inactivation(XCI) travels less successfully in autosomal than inX-chromosomal chromatin. The interspersed repeatelements LINE1s (L1s) have been suggested as candidates for“boosters” which promote the spread of XCI in the X-chromosome.The present paper reviews the current evidence concerning thepossible role of L1s in XCI. Recent evidence, accruing from thehuman genome sequencing project and other sources, confirms thatmammalian X-chromosomes are indeed rich in L1s, except in regionswhere there are many genes escaping XCI. The density of L1s is thehighest in the evolutionarily oldest regions. Recent work on X;autosome translocations in human and mouse suggested failure ofstabilization of XCI in autosomal material, so that genes arereactivated, but resistance of autosomal genes to the originalsilencing is not excluded. The accumulation of L1s on theX-chromosome may have resulted from reduced recombination or latereplication. Whether L1s are part of the mechanism of XCI or aresult of it remains enigmatic.

[学科分类] 基础医学