title: β3 integrin-EGF receptor cross-talk activates p190RhoGAP in mouse mammary gland epithelial cells.
abstract: Active RhoA localizes to plasma membrane, where it stimulates formation of focal adhesions and stress fibers. RhoA activity is inhibited by p190RhoGAP following integrin-mediated cell attachment to allow sampling of new adhesive environments. p190RhoGAP is itself activated by Src-dependent tyrosine phosphorylation, which facilitates complex formation with p120RasGAP. This complex then translocates to the cell surface, where p190RhoGAP down-regulates RhoA. Here we demonstrate that the epidermal growth factor receptor (EGFR) cooperates with β3 integrin to regulate p190RhoGAP activity in mouse mammary gland epithelial cells. Adhesion to fibronectin stimulates tyrosine phosphorylation of the EGFR in the absence of receptor ligands. Use of a dominant inhibitory EGFR mutant demonstrates that fibronectin-activated EGFR recruits p120RasGAP to the cell periphery. Expression of an inactive β3 integrin subunit abolishes p190RhoGAP tyrosine phosphorylation, demonstrating a mechanistic link between β3 integrin-activated Src and EGFR regulation of the RhoA inhibitor. The β3 integrin/EGFR pathway also has a positive role in formation of filopodia. Together our data suggest that EGFR constitutes an important intrinsic migratory cue since fibronectin is a key component of the microenvironment in normal mammary gland development and breast cancer. Our data also suggest that EGFR expressed at high levels has a role in eliciting cell shape changes associated with epithelial-to-mesenchymal transition.
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Nikolas
authors.initials: N
authors.lastname: Balanis
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yoshigi
authors.forename: Michael K
authors.initials: MK
authors.lastname: Wendt
authors.forename: William P
authors.initials: WP
authors.lastname: Schiemann
authors.forename: Cathleen R
authors.initials: CR
authors.lastname: Carlin
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D004815:Epidermal Growth Factor / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D022001:Focal Adhesions / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D039661:Integrin beta3 / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011554:Pseudopodia / Q000378:metabolism; D020239:Receptor Cross-Talk; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D020729:p120 GTPase Activating Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000096:biosynthesis / Q000378:metabolism
chemical_list: C513042:Arhgap5 protein, mouse; D005353:Fibronectins; D020690:GTPase-Activating Proteins; D039661:Integrin beta3; D020729:p120 GTPase Activating Protein; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D020742:rhoA GTP-Binding Protein