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NCBI Summary:
This gene encodes a member of the claudin family. Claudins are integral membrane proteins and components of tight junction strands. Tight junction strands serve as a physical barrier to prevent solutes and water from passing freely through the paracellular space between epithelial or endothelial cell sheets, and also play critical roles in maintaining cell polarity and signal transductions. Differential expression of this gene has been observed in different types of malignancies, including breast cancer, ovarian cancer, hepatocellular carcinomas, urinary tumors, prostate cancer, lung cancer, head and neck cancers, thyroid carcinomas, etc.. Alternatively spliced transcript variants encoding different isoforms have been found.[provided by RefSeq, May 2010]
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CLAUDIN7 modulates trophectoderm barrier function to maintain blastocyst development in pigs. Gao D et al. (2020) 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.//////////////////
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Expression of claudins 1, 4, 5, and 7 in ovarian tumors of diverse types. Soini Y et al. SUMMARY:: In this study, 60 different types of ovarian lesions, mainly consisting of ovarian neoplasms, were studied for the expression of claudins 1, 4, 5, and 7. Strong expression of claudins 1, 4, and 7 was seen in benign and malignant epithelial ovarian tumors. Expression of claudin 5, reported to be mainly present in endothelial cells, was seen in ovarian epithelial tumors, but with a significantly lower frequency than claudins 1, 4, and 7. On the contrary, sex-cord stromal tumors and cysts, such as fibromas/thecomas, Sertoli-Leydig cell tumors, granulosa cell tumors, and follicular and luteinized cysts were mainly negative for claudins 1, 4, 5, and 7. Interestingly, adenomatoid tumors did not express claudin 5, which is in agreement with their non-endothelial nature. They were also negative for claudin 4, but expressed claudins 1 and 7, but to a lesser degree than epithelial lesions. In immature teratomas, the epithelial component was usually positive whereas other components were negative for these claudins. Dysgerminomas did not express any of the claudins studied. The results show that claudins 1, 4, and 7 are mainly expressed in ovarian epithelial tumors and can thus be used to indicate epithelial differentiation in them. Eventhough considered an endothelial marker, claudin 5 was also present in a subset of epithelial lesions. However, this claudin can be used to differentiate adenomatoid tumors from vascular lesions. No significant difference was seen between epithelial benign and malignant lesions, except for claudin 5, which seemed stronger in malignant epithelial tumors.
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