Department of Medical Chemistry, University of Debrecen Medical and Health Science Center, Debrecen, Hungary.
PLoS One. 2012;7(4):e35595. doi: 10.1371/journal.pone.0035595. Epub 2012 Apr 16.
Ezrin-radixin-moesin (ERM)-binding phosphoprotein 50 (EBP50) is a phosphorylatable PDZ domain-containing adaptor protein that is abundantly expressed in epithelium but was not yet studied in the endothelium. We report unusual nuclear localization of EBP50 in bovine pulmonary artery endothelial cells (BPAEC). Immunofluorescent staining and cellular fractionation demonstrated that EBP50 is present in the nuclear and perinuclear region in interphase cells. In the prophase of mitosis EBP50 redistributes to the cytoplasmic region in a phosphorylation dependent manner and during mitosis EBP50 co-localizes with protein phosphatase 2A (PP2A). Furthermore, in vitro wound healing of BPAEC expressing phospho-mimic mutant of EBP50 was accelerated indicating that EBP50 is involved in the regulation of the cell division. Cell cycle dependent specific interactions were detected between EBP50 and the subunits of PP2A (A, C, and Bα) with immunoprecipitation and pull-down experiments. The interaction of EBP50 with the Bα containing form of PP2A suggests that this holoenzyme of PP2A can be responsible for the dephosphorylation of EBP50 in cytokinesis. Moreover, the results underline the significance of EBP50 in cell division via reversible phosphorylation of the protein with cyclin dependent kinase and PP2A in normal cells.
Ezrin-radixin-moesin（ERM）结合磷蛋白 50（EBP50）是一种可磷酸化的 PDZ 结构域包含衔接蛋白，在上皮细胞中大量表达，但在血管内皮细胞中尚未研究。我们报告了牛肺动脉内皮细胞（BPAEC）中 EBP50 异常的核定位。免疫荧光染色和细胞分级分离表明，EBP50 存在于间期细胞的核和核周区。在有丝分裂前期，EBP50 依赖于磷酸化的方式重新分布到细胞质区域，在有丝分裂过程中，EBP50 与蛋白磷酸酶 2A（PP2A）共定位。此外，表达 EBP50 磷酸模拟突变体的 BPAEC 的体外划痕愈合加快表明 EBP50 参与细胞分裂的调节。通过免疫沉淀和下拉实验检测到 EBP50 与 PP2A 的亚基（A、C 和 Bα）之间在细胞周期依赖性的特异性相互作用。EBP50 与含有 Bα 的 PP2A 形式的相互作用表明，这种 PP2A 的全酶可以负责胞质分裂中 EBP50 的去磷酸化。此外，这些结果强调了 EBP50 在正常细胞中通过细胞周期依赖性蛋白激酶和 PP2A 对蛋白质的可逆磷酸化在细胞分裂中的重要性。
