School of Life and Environmental Sciences, University of Sydney, Sydney, Australia.
School of Medical Sciences and Bosch Institute, University of Sydney, Sydney, Australia.
Mol Reprod Dev. 2019 Jun;86(6):639-649. doi: 10.1002/mrd.23140. Epub 2019 Apr 4.
The fluid that surrounds the embryo in the uterus contains important nourishing factors and secretions. To maintain the distinct microenvironment in the uterine lumen, the tight junctions between uterine epithelial cells are remodeled to decrease paracellular movement of molecules and solutes. Modifications to tight junctions between uterine epithelial cells is a common feature of pregnancy in eutherian mammals, regardless of placental type. Here we used immunofluorescence microscopy and western blot analysis to describe distributional changes to tight junctional proteins, claudin-1, -3, -4, and -5, in the uterine epithelial cells of a marsupial species, Sminthopsis crassicaudata. Immunofluorescence microscopy revealed claudin-1, -3, and -5 in the tight junctions of the uterine epithelium of S. crassicaudata during pregnancy. These specific claudins are associated with restricting passive movement of fluid between epithelial cells in eutherians. Hence, their function during pregnancy in S. crassicaudata may be to maintain the uterine luminal content surrounding developing embryos. Claudin-4 disappears from all uterine regions of S. crassicaudata at the time of implantation, in contrast with the distribution of this claudin in some eutherian mammals. We conclude that like eutherian mammals, distributional changes to claudins in the uterine epithelial cells of S. crassicaudata are necessary to support pregnancy. However, the combination of individual claudin isoforms in the tight junctions of the uterine epithelium of S. crassicaudata differs from that of eutherian mammals. Our findings suggest that the precise permeability of the paracellular pathway of the uterine epithelium is species-specific.
胚胎周围的羊水含有重要的营养因子和分泌物。为了维持子宫腔内独特的微环境，子宫上皮细胞之间的紧密连接会重塑，以减少分子和溶质的旁细胞运动。在有胎盘的真兽类哺乳动物中，无论胎盘类型如何，改变子宫上皮细胞之间的紧密连接是妊娠的共同特征。在这里，我们使用免疫荧光显微镜和蛋白质印迹分析来描述有袋动物物种 Sminthopsis crassicaudata 子宫上皮细胞中紧密连接蛋白（claudin-1、-3、-4 和 -5）的分布变化。免疫荧光显微镜显示，在 S. crassicaudata 妊娠期间，claudin-1、-3 和 -5 位于子宫上皮细胞的紧密连接处。这些特定的 Claudin 与限制真兽类上皮细胞之间的液体被动运动有关。因此，它们在 S. crassicaudata 妊娠期间的功能可能是维持围绕发育中胚胎的子宫腔内容物。Claudin-4 在 S. crassicaudata 的植入时从所有子宫区域消失，与该 Claudin 在一些真兽类哺乳动物中的分布形成对比。我们得出的结论是，与真兽类哺乳动物一样，S. crassicaudata 子宫上皮细胞中 Claudin 的分布变化对于支持妊娠是必要的。然而，S. crassicaudata 子宫上皮细胞紧密连接中单个 Claudin 同工型的组合与真兽类哺乳动物不同。我们的研究结果表明，子宫上皮细胞旁细胞途径的精确通透性是具有物种特异性的。
