García-Godínez Alejandro, Contreras Rubén Gerardo, González-Del-Pliego Margarita, Aguirre-Benítez Elsa, Acuña-Macías Isabel, de la Vega M Teresa, Martín-Tapia Dolores, Solano-Agama Carmen, Mendoza-Garrido M Eugenia
Department of Physiology, Biophysics and Neuroscience, CINVESTAV-IPN, Mexico City, Mexico.
Cell Tissue Res. 2014 Jul;357(1):309-21. doi: 10.1007/s00441-014-1827-7. Epub 2014 Apr 24.
Follicle-stellate cells are pituitary non-granular cells that are arranged between secretory cells or organized in follicles with small lumens. Cells from the follicles exhibit the typical phenotype of a transporting epithelium, including apical microvilli with a cilium and tight junctions. Freeze-fracture electron microscopy images show that the tight junctions consist of 5-7 anastomosing strands and that cultured follicle-stellate cells develop a trans-epithelial electrical resistance characteristic of "tight" epithelia. Here, we investigate the molecular composition of the tight junction from follicle stellate cells. We found that the rat anterior pituitary lobe expresses mRNAs for claudins 2, 4 and 5; the proteins of all these claudins are observed in the anterior lobe, whereas the intermediate lobe expresses claudins 2 and 5 and the posterior lobe contains only claudin 5. Follicle-stellate cells, identified by their protein marker S100β, expresses claudin 4 in the apical membrane, in co-localization with dipeptidyl-peptidase and near acetylated β-tubulin. Claudin 4 partially co-localizes with E-cadherin, indicating that a fraction of the protein is located in the basolateral domain. Follicle-stellate-enriched cell cultures develop patches of polygonal cells expressing claudin 4 and E-cadherin, encircled by extensive monolayers of fusiform cells. Claudin 2 stains specifically blood vessels, identified by claudin 5 and VE-cadherin labels. Thus, follicles in the anterior pituitary consist of "tight" epithelia that can carry out intense vectorial transport, together with a high cation movement in blood vessels, possibly related to the ion requirements of excitable secretory cells for hormone secretion.
滤泡星形细胞是垂体中的无颗粒细胞，它们排列在分泌细胞之间或形成具有小腔的滤泡。滤泡中的细胞表现出转运上皮细胞的典型表型，包括带有纤毛的顶端微绒毛和紧密连接。冷冻蚀刻电子显微镜图像显示，紧密连接由5-7条吻合的链组成，培养的滤泡星形细胞形成具有“紧密”上皮细胞特征的跨上皮电阻。在此，我们研究滤泡星形细胞紧密连接的分子组成。我们发现大鼠垂体前叶表达claudin 2、4和5的mRNA；所有这些claudin的蛋白质在前叶中都有观察到，而中间叶表达claudin 2和5，后叶仅含有claudin 5。通过其蛋白质标志物S100β鉴定的滤泡星形细胞，在顶端膜中表达claudin 4，与二肽基肽酶共定位并靠近乙酰化β微管蛋白。Claudin 4与E-钙粘蛋白部分共定位，表明一部分蛋白质位于基底外侧结构域。富含滤泡星形细胞的细胞培养物形成表达claudin 4和E-钙粘蛋白的多边形细胞斑块，周围是由梭形细胞组成的广泛单层。Claudin 2特异性标记血管，血管由claudin 5和VE-钙粘蛋白标记鉴定。因此，垂体前叶的滤泡由能够进行强烈矢量运输的“紧密”上皮细胞组成，同时血管中有高阳离子移动，这可能与可兴奋分泌细胞分泌激素的离子需求有关。
