Cox Christopher M, Mandell Edward K, Stewart Lorraine, Lu Ruifeng, Johnson Debra L, McCarter Sarah D, Tavares Andre, Runyan Ray, Ghosh Sourav, Wilson Jean M
Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724.
Department of Neurology, Yale University School of Medicine, New Haven, CT 06511.
Mol Biol Cell. 2015 Jul 15;26(14):2673-84. doi: 10.1091/mbc.E15-04-0224. Epub 2015 May 20.
Contact-mediated inhibition of cell proliferation is an essential part of organ growth control; the transcription coactivator Yes-associated protein (YAP) plays a pivotal role in this process. In addition to phosphorylation-dependent regulation of YAP, the integral membrane protein angiomotin (AMOT) and AMOT family members control YAP through direct binding. Here we report that regulation of YAP activity occurs at the endosomal membrane through a dynamic interaction of AMOT with an endosomal integral membrane protein, endotubin (EDTB). EDTB interacts with both AMOT and occludin and preferentially associates with occludin in confluent cells but with AMOT family members in subconfluent cells. EDTB competes with YAP for binding to AMOT proteins in subconfluent cells. Overexpression of the cytoplasmic domain or full-length EDTB induces translocation of YAP to the nucleus, an overgrowth phenotype, and growth in soft agar. This increase in proliferation is dependent upon YAP activity and is complemented by overexpression of p130-AMOT. Furthermore, overexpression of EDTB inhibits the AMOT:YAP interaction. EDTB and AMOT have a greater association in subconfluent cells compared with confluent cells, and this association is regulated at the endosomal membrane. These data provide a link between the trafficking of tight junction proteins through endosomes and contact-inhibition-regulated cell growth.
接触介导的细胞增殖抑制是器官生长控制的重要组成部分；转录共激活因子Yes相关蛋白（YAP）在此过程中起关键作用。除了YAP的磷酸化依赖性调节外，整合膜蛋白血管动蛋白（AMOT）及其家族成员通过直接结合来控制YAP。我们在此报告，YAP活性的调节发生在内体膜上，通过AMOT与一种内体整合膜蛋白内毒素（EDTB）的动态相互作用实现。EDTB与AMOT和闭合蛋白相互作用，在汇合细胞中优先与闭合蛋白结合，而在亚汇合细胞中与AMOT家族成员结合。在亚汇合细胞中，EDTB与YAP竞争结合AMOT蛋白。细胞质结构域或全长EDTB的过表达诱导YAP易位至细胞核，呈现过度生长表型，并在软琼脂中生长。这种增殖增加依赖于YAP活性，并可通过p130-AMOT的过表达得到补充。此外，EDTB的过表达抑制AMOT与YAP的相互作用。与汇合细胞相比，EDTB与AMOT在亚汇合细胞中的结合更强，且这种结合在内体膜上受到调节。这些数据揭示了紧密连接蛋白通过内体的运输与接触抑制调节的细胞生长之间的联系。
