RNA-seq profiling of neural tissue from mouse embryos with combined loss of p53 and Bim

Neural tube defects (NTDs) are common birth defects in humans and show an unexplained female bias. Female mice lacking the tumor suppressor p53 display NTDs with incomplete penetrance. We found that the combined loss of pro-apoptotic BIM and p53 caused 100% penetrant, female-exclusive NTDs, which allowed us to investigate the female-specific functions of p53. We report that female p53-/- neural tube samples show fewer cells with inactive X markers Xist and H3K27me3, and a concomitant increase in biallelic expression of the X-linked genes, Huwe1 and Usp9x. The depletion of Xist and increase X-linked gene expression was confirmed by RNA sequencing. Compound mutant mice were generated by inter-crossing single mutant strains previously described (PMID: 7922305, PMID: 10576740). RNA was extracted from neural tissue from E9.5 Bim-/+ mouse embryos. RNA-seq profiling was undertaken for n=4 affected female embryos (p53 knockout), n=4 control male mice (p53 knockout) and n=3 control female embryos (p53 wildtype).神经管缺陷（Neural tube defects, NTDs）是人类常见的出生缺陷，且表现出无法解释的雌性偏倚现象。缺失肿瘤抑制因子p53的雌性小鼠可出现外显率不完全的神经管缺陷。本研究发现，联合缺失促凋亡蛋白BIM与p53可导致100%外显且仅雌性发生的神经管缺陷，这为探究p53的雌性特异性功能提供了理想的研究模型。我们的研究显示，p53敲除（p53-/-）的雌性小鼠神经管样本中，携带X染色体失活标记Xist与H3K27me3的细胞数量显著减少，同时X连锁基因Huwe1及Usp9x的双等位基因表达比例显著升高。上述Xist表达下调及X连锁基因表达升高的现象，已通过RNA测序（RNA-seq）得到验证。本研究中的复合突变小鼠通过互交此前已报道的单突变品系构建获得（PMID: 7922305、PMID: 10576740）。我们从E9.5期Bim杂合（Bim-/+）小鼠胚胎的神经组织中提取总RNA，对n=4例患病雌性p53敲除胚胎、n=4例对照雄性p53敲除小鼠及n=3例对照雌性p53野生型小鼠开展RNA测序分析。