Distinct Roles for Rho Versus Rac/Cdc42 GTPases Downstream of Vav2 in Regulating Mammary Epithelial Acinar Architecture

作者:Duan Lei*; Chen Gengsheng; Virmani Sumeet; Ying GuoGuang; Raja Srikumar M; Chung Byung Min; Rainey Mark A; Dimri Manjari; Ortega Cava Cesar F; Zhao Xiangshan; Clubb Robert J; Tu Chun; Reddi Alagarsamy L; Naramura Mayumi; Band Vimla; Band Hamid
来源:JOURNAL OF BIOLOGICAL CHEMISTRY, 2010, 285(2): 1555-1568.
DOI:10.1074/jbc.M109.057976

摘要

Non-malignant mammary epithelial cells (MECs) undergo acinar morphogenesis in three-dimensional Matrigel culture, a trait that is lost upon oncogenic transformation. Rho GTPases are thought to play important roles in regulating epithelial cell-cell junctions, but their contributions to acinar morphogenesis remain unclear. Here we report that the activity of Rho GTPases is down-regulated in non-malignant MECs in three-dimensional culture with particular suppression of Rac1 and Cdc42. Inducible expression of a constitutively active form of Vav2, a Rho GTPase guanine nucleotide exchange factor activated by receptor tyrosine kinases, in three-dimensional MEC culture activated Rac1 and Cdc42; Vav2 induction from early stages of culture impaired acinar morphogenesis, and induction in preformed acini disrupted the pre-established acinar architecture and led to cellular outgrowths. Knockdown studies demonstrated that Rac1 and Cdc42 mediate the constitutively active Vav2 phenotype, whereas in contrast, RhoA knockdown intensified the Vav2-induced disruption of acini, leading to more aggressive cell outgrowth and branching morphogenesis. These results indicate that RhoA plays an antagonistic role to Rac1/Cdc42 in the control of mammary epithelial acinar morphogenesis.