D-repeat in the XIST gene is required for X chromosome inactivation

Although it has been revealed that the A-repeat contributes to the X chromosome inactivation (X-inactivation), the role of the longest D-repeat has not yet been investigated. Here, a sgRNA directed CRISPR/Cas9 system which have multiple target sites within repeat D of XIST , were used to generate D-repeat deletion and studied its roles on X-inactivation.

The results showed that the deletion of D-repeat caused a significantly decreased expression of XIST , and up regulated expression of X-linked genes, suggesting that the D-repeat may play an important role in the regulation of XIST expression and silencing of the X-linked genes, which could provide a new idea in the molecular mechanisms of X-inactivation.