Elsevier

Brain Research

Volume 1126, Issue 1, 18 December 2006, Pages 46-49
Brain Research

Short Communication
High expression of the mammalian X chromosome in brain

https://doi.org/10.1016/j.brainres.2006.08.053Get rights and content

Abstract

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.

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Acknowledgments

This work was supported by grants from the National Institutes of Health. We thank M.K. Cheng for helpful comments.

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