Nguyen Di Kim, Disteche Christine M
Department of Pathology, University of Washington, Seattle, WA 98195, USA.
Brain Res. 2006 Dec 18;1126(1):46-9. doi: 10.1016/j.brainres.2006.08.053. Epub 2006 Sep 15.
Divergence between the sex chromosomes has led to loss and differentiation of Y-linked genes and haplo-insufficiency for X-linked genes in males. A mechanism of dosage compensation, for which we recently found evidence in mammals, evolved to restore a balanced expression of the genome by doubling the transcriptional output from the X chromosome. X inactivation would then serve to avoid hyper-transcription of X-linked genes in females by silencing one X chromosome. We also found that, compared to the rest of the genome, the X chromosome contains an excess of genes highly expressed in brain tissues. The exceptionally important role of the X chromosome in brain function, evident from the prevalence of X-linked forms of mental retardation, is discussed in view of sex chromosome regulation and evolution and sexual reproduction.
性染色体之间的差异导致了Y连锁基因的丢失和分化以及雄性中X连锁基因的单倍体不足。我们最近在哺乳动物中发现了一种剂量补偿机制，该机制通过使X染色体的转录输出加倍来恢复基因组的平衡表达。X染色体失活随后通过沉默一条X染色体来避免雌性中X连锁基因的过度转录。我们还发现，与基因组的其他部分相比，X染色体包含大量在脑组织中高表达的基因。鉴于性染色体的调控、进化和有性生殖，讨论了X染色体在脑功能中极其重要的作用，这一点从X连锁形式的智力迟钝的普遍性中可见一斑。
