Caveolae and caveolin-1 in human term villous trophoblast
Caveolae and caveolin-1 in human term villous trophoblast
复制标题
DOI：
10.1016/s0143-4004(03)00106-1
复制
发表时间：
2003-08-01
期刊：
影响因子：
3.8
通讯作者：
Redman, CWG
中科院分区：
文献类型：
--
作者：
Linton, EA;Rodriguez-Linares, B;Redman, CWG
小窝是在许多细胞类型，特别是内皮细胞中发现的质膜的烧瓶状内陷。一个主要的结构成分是膜蛋白小窝蛋白-1，它与许多信号分子，包括内皮一氧化氮（eNOS）。Caveolin-1在内皮细胞制备物中与eNOS共免疫沉淀，调节eNOS活性，使其保持非活性。关于滋养层细胞中存在小窝和小窝蛋白-1目前存在争议，因此进行本研究以检查人合体滋养层细胞中表达的高水平eNOS是否与小窝蛋白-1相关，免疫组化显示，足月胎盘中的细胞膜小窝蛋白表达较弱，1在合体滋养层细胞中，尽管终末绒毛血管内皮染色强烈。电镜下可见绒毛毛细血管内皮细胞内有大量小窝，但在合胞体中极为少见。小窝蛋白-1染色在纯化、分离的足月绒毛细胞滋养层细胞中广泛存在，这些细胞角蛋白阳性细胞的纯度通过细胞离心涂片分析和流式细胞术证实。纯化的细胞滋养层细胞超微结构切片中可见明显的小窝。研究了绒毛细胞滋养层细胞向合体滋养层细胞分化过程中小窝蛋白-1和eNOS表达的时程。Western分析显示，在第1天全细胞裂解物中明显的小窝蛋白-1表达在第3天细胞合胞化时降低，并在第6天进一步降低，而肌动蛋白（对照）的水平保持较高。在相同的样品中eNOS表达遵循不同的模式，在培养的第1天细胞中的低水平到第3天显著增加，到第6天再次下降。eNOS与小窝蛋白-1在第1天和第3天滋养层培养物中的关联通过eNOS与小窝蛋白-1共免疫沉淀以及反之亦然的证明来证明。我们的结论是，人类绒毛细胞滋养层表达小窝蛋白-1，组装成小窝。分化成合胞体导致小窝蛋白-1的表达减少，但不是消失，小窝的显著减少。
Caveolae are flask-shaped invaginations of the plasma membrane found in many cell types, particularly endothelium. A major structural component is the membrane protein caveolin-1 which associates with numerous signalling molecules, including endothelial nitric oxide (eNOS). Caveolin-1, which co-immunoprecipitates with eNOS in preparations from endothelial cells, regulates eNOS activity, holding it inactive. Controversy now exists regarding the presence of caveolae and caveolin-1 in trophoblasts, hence this study was carried out to examine whether the high levels of eNOS expressed in human syncytiotrophoblast are associated with caveolin-1, and to find out if caveolae are present in villous cytotrophoblasts and syncytiotrophoblast.Immunohistochemistry of term placentae revealed only weak labelling for caveolin-1 in the syncytiotrophoblast although the endothelium of the terminal villus vessels stained strongly. By electron microscopy, numerous caveolae were identified in the villus capillary endothelium but were extremely rare in the syncytium. Caveolin-1 staining was extensive in purified, isolated term villous cytotrophoblasts, with the purity of these cytokeratin positive cells confirmed by cytospin analysis and flow cytometry. Caveolae were Clearly demonstrated in ultrastructural sections of the purified cytotrophoblasts. The time course of expression of caveolin-1 and eNOS during differentiation of villous cytotrophoblast into syncytiotrophoblast in culture was studied. Western analysis showed that caveolin-1 expression evident in day 1 whole cell lysates decreased at day 3 when the cells had syncytialized and declined further by day 6, while the levels of actin (control) remained high. eNOS expression in the same samples followed a different pattern, with the low levels in day 1 cells increasing substantially by 3 days in culture, subsiding again by day 6. eNOS association with caveolin-1 in day 1 and day 3 trophoblast cultures was evidenced by the demonstration that eNOS co-immunoprecipitates with caveolin-1 and vice versa. We conclude that human villous cytotrophoblasts express caveolin-1, which assembles into caveolae. Differentiation into syncytium results in a decrease, but not disappearance, of expression of caveolin-1 and a marked reduction of the caveolae.