Trophectoderm (TE) barrier function is an essential prerequisite for blastocyst development. CLAUDIN7 (CLDN7), a member of CLAUDINS family, is involved in regulating intercellular exchange and cell polarity in epithelium cells. However, the role of CLDN7 in porcine early embryo development is yet to be explored. Here, we found that CLDN7 was highly conserved in different species and was widely expressed in different tissues. Remarkably, CLDN7 expression maintained a low level from GV oocyte to 4-cell stage whereas its expression exhibited a higher level from 8-cell stage onwards. Microinjection of siRNA into cytoplasm effectively knocked down expression of CLDN7 mRNA and protein in porcine embryos. CLDN7 knockdown not only significantly reduced blastocyst rates of embryos derived from parthenogenetic activation and in vitro fertilization, but also reduced number of total cells and TE cells in the resulting blastocysts. Furthermore, CLDN7 knockdown led to a significant reduction in expression of multiple genes associated with tight junction assembly and fluid accumulation. A permeability assay revealed that CLDN7 knockdown disrupted tight junction assembly and paracellular sealing in the TE epithelium. Taken together, these results demonstrate that CLDN7 regulates porcine blastocyst development via modulating trophectoderm barrier function.

中文翻译：

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CLAUDIN7 调节滋养外胚层屏障功能以维持猪囊胚发育


滋养外胚层 (TE) 屏障功能是囊胚发育的重要先决条件。 CLAUDIN7 (CLDN7) 是 CLAUDINS 家族的成员，参与调节上皮细胞的细胞间交换和细胞极性。然而，CLDN7在猪早期胚胎发育中的作用仍有待探索。在这里，我们发现CLDN7在不同物种中高度保守，并且在不同组织中广泛表达。值得注意的是，从 GV 卵母细胞到 4 细胞阶段，CLDN7 表达保持较低水平，而从 8 细胞阶段开始，其表达表现出较高水平。将 siRNA 显微注射到细胞质中，可有效降低猪胚胎中 CLDN7 mRNA 和蛋白的表达。 CLDN7敲除不仅显着降低了孤雌激活和体外受精胚胎的囊胚率，而且还减少了所得囊胚中的总细胞和TE细胞数量。此外，CLDN7 敲低导致与紧密连接组装和积液相关的多个基因的表达显着减少。渗透性测定显示，CLDN7 敲低破坏了 TE 上皮中的紧密连接组装和细胞旁密封。综上所述，这些结果表明 CLDN7 通过调节滋养外胚层屏障功能来调节猪囊胚发育。