Kwon Jeong-Woo, Kim Nam-Hyung, Choi Inchul
Department of Animal SciencesChungbuk National University, Gaesin-Dong, Cheongju, Chungbuk 28644, Republic of KoreaDepartment of Animal and Dairy SciencesCollege of Agriculture and Life Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
Reproduction. 2016 Apr;151(4):297-304. doi: 10.1530/REP-15-0397. Epub 2016 Jan 4.
Coxsackie virus and adenovirus receptor (CXADR) is a member of the immunoglobulin superfamily as well as a member of the junctional adhesion molecule family of adhesion receptor. In human pre-implantation embryos, CXADR was detected and co-localized with tight junction (TJ) proteins on the membrane of the trophectoderm. However, its physiological roles were not elucidated in terms of blastocyst formation. Here, we reported expression patterns and biological functions of CXADR in porcine pre-implantation embryos. The transcripts of CXADR were detected at all stages of pre-implantation. Particularly, its expression dramatically increased and preferentially localized at the edge of cell-cell contacts, rather than in the nucleus from the eight-cell stage onwards. CXADR expression was knocked down (KD) by microinjecting double-stranded RNA into one-cell parthenotes. The vast majority of CXADR KD embryos failed to develop to the blastocyst stage, and a few developed KD blastocysts did not expand fully. Analysis of adherens junction (AJ)- and TJ-associated genes/proteins using qRT-PCR, immunocytochemistry and assessment of TJ permeability using FITC-dextran uptake assay revealed that the developmental failure and relatively small cavities are attributed to the defects of TJ assembly. In summary, CXADR is necessary for the AJ and TJ assembly/biogenesis during pre-implantation development.
柯萨奇病毒和腺病毒受体（CXADR）是免疫球蛋白超家族的成员，也是黏附受体连接黏附分子家族的成员。在人类植入前胚胎中，检测到CXADR并与滋养外胚层膜上的紧密连接（TJ）蛋白共定位。然而，就囊胚形成而言，其生理作用尚未阐明。在此，我们报道了CXADR在猪植入前胚胎中的表达模式和生物学功能。在植入前的各个阶段均检测到CXADR的转录本。特别是，从八细胞阶段开始，其表达显著增加，并优先定位于细胞间接触的边缘，而非细胞核中。通过将双链RNA显微注射到单细胞孤雌胚胎中来敲低（KD）CXADR的表达。绝大多数CXADR KD胚胎未能发育到囊胚阶段，少数发育成的KD囊胚也未完全扩张。使用qRT-PCR、免疫细胞化学分析黏附连接（AJ）和TJ相关基因/蛋白，并使用FITC-葡聚糖摄取试验评估TJ通透性，结果显示发育失败和相对较小的腔隙归因于TJ组装缺陷。总之，CXADR在植入前发育过程中对AJ和TJ的组装/生物发生是必需的。
