title: The transforming Rho family GTPase Wrch-1 disrupts epithelial cell tight junctions and epithelial morphogenesis.
abstract: Wrch-1, an atypical and transforming Rho GTPase, regulates cellular activities including proliferation and actin organization, but its functions and effectors remain poorly characterized. We show here that Wrch-1 distributes along the apical and basolateral membranes in MDCK cells and binds the cell polarity protein Par6 in a GTP-dependent manner. Activated Wrch-1 negatively regulates the kinetics of tight junction (TJ) assembly during epithelial cell polarization but has no detectable effect on overall cell polarity in confluent monolayers. It also causes a dramatic cytoskeletal reorganization and multilayering in cells grown in two-dimensional culture and disrupts cystogenesis of cells grown in three-dimensional (3D) culture. Similarly, short hairpin RNA-mediated knockdown of Wrch-1 perturbs cystogenesis in 3D culture, suggesting that tight regulation of Wrch-1 activity is necessary for normal epithelial morphogenesis. A weakly transforming effector domain mutant of activated Wrch-1 that inhibits Par6 binding abrogates the ability of Wrch-1 to disrupt TJ formation, actin organization, and epithelial morphogenesis. We hypothesize that Wrch-1-induced morphological and growth transformation may occur in part through Par6-mediated disruption of TJs and actin organization.
authors.affiliation: Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7512, USA.
authors.forename: Donita C
authors.initials: DC
authors.lastname: Brady
authors.forename: Jamie K
authors.initials: JK
authors.lastname: Alan
authors.forename: James P
authors.initials: JP
authors.lastname: Madigan
authors.forename: Alan S
authors.initials: AS
authors.lastname: Fanning
authors.forename: Adrienne D
authors.initials: AD
authors.lastname: Cox
mesh_terms: D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion / Q000187:drug effects; D016764:Cell Polarity / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002522:Chlorocebus aethiops; D004285:Dogs; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004848:Epithelium / Q000187:drug effects / Q000196:embryology* / Q000201:enzymology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D009024:Morphogenesis / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology*; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C499657:PARD6A protein, human; D006160:Guanosine Triphosphate; D020741:rho GTP-Binding Proteins