The human XIST RNA gene is located on the q arm of X chromosomes within a region
ID: 70496 • Letter: T
Question
The human XIST RNA gene is located on the q arm of X chromosomes within a region called the X Inactivation Center (XIC). The XIST gene has many CpG islands and is expressed exclusively from the XIC of the inactive X chromosome. The transcript is spliced but apparently does not encode a protein. The transcript remains in the nucleus where it coats the inactive X chromosome leading to X-inactivation and formation of the Barr body. Would you expect the CpG islands upstream of the XIST gene to be methylated? Why or why not.
Explanation / Answer
Yes it is differentially methylated. because differentially methylated cPG island within human xist mediates alternative P2 transcription and YY1 bibinding
Female specific DNAse hypersensitivity site within XIST is specific to the inactivation of X chromosome and correlates with internal transcription of P2 promoter. P2 is located within cPG island that is differentially methylated between males and females and overlaps cconserved YY1 binding sites that are bound on inactive X chromosome where sites are un methylated. Depletion of YY1 untethers the Xist RNA and decreases transcription of XIST
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