Unraveling the role of Xist in X chromosome inactivation: insights from rabbit model and deletion analysis of exons and repeat A

X chromosome inactivation (XCI) is a process that equalizes the expression of X-linked genes between males and females. It relies on Xist , continuously expressed in somatic cells during XCI maintenance. However, how Xist impacts XCI maintenance and its functional motifs remain unclear. In this study, we conducted a comprehensive analysis of Xist , using rabbits as an ideal non-primate model. Homozygous knockout of exon 1, exon 6, and repeat A in female rabbits resulted in embryonic lethality. However, X ∆ReA X females, with intact X chromosome expressing Xist , showed no abnormalities. Interestingly, there were no significant differences between females with homozygous knockout of exons 2–5 and wild-type rabbits, suggesting that exons 2, 3, 4, and 5 are less important for XCI. These findings provide evolutionary insights into Xist function.