X Inactivation:A Special Form of Gene Regulation
Chen Yundi Zeng Yitao (Shanghai Institute of Medical Genetics,Shanghai Children's Hospital,Shanghai 200040)
Dosage compensation is the process by which the levels of X linked gene expression is equalized between the sexes. The strategies used to accomplish dosage compensation are varied. In eutherian mammals,dosage compensation is achived by random inactivating one of the two X chromosomes in the female. X inactivation starts at the X inactivation center(XIC) and spreads throughout the chromosome. The XIST gene maps to the XIC region on the mouse and human X chromosome and is thought to be involved in the initiation of inactivation,making it a strong candidate for XIC itself. The genes that escape X inactivation have been recently found in human and in mouse. Study on the mechanisms of ‘escape’ is helpful to the understanding of gene regulation by X inactivation. The Xinactivation status of some genes differs significantly between human and mouse,suggesting continuous evolutionary changes in the sex chromosomes.
【CateGory Index】： Q343.2