title: Erbin and the NF2 tumor suppressor Merlin cooperatively regulate cell-type-specific activation of PAK2 by TGF-beta.
abstract: Transforming growth factor beta (TGF-beta) family ligands are pleotropic proteins with diverse cell-type-specific effects on growth and differentiation. For example, PAK2 activation is critical for the proliferative/profibrotic action of TGF-beta on mesenchymal cells, and yet it is not responsive to TGF-beta in epithelial cells. We therefore investigated the regulatory constraints that prevent inappropriate PAK2 activation in epithelial cultures. The results show that the epithelial-enriched protein Erbin controls the function of the NF2 tumor suppressor Merlin by determining the output of Merlin's physical interactions with active PAK2. Whereas mesenchymal TGF-beta signaling induces PAK2-mediated inhibition of Merlin function in the absence of Erbin, Erbin/Merlin complexes bind and inactivate GTPase-bound PAK2 in epithelia. These results not only identify Erbin as a key determinant of epithelial resistance to TGF-beta signaling, they also show that Erbin controls Merlin tumor suppressor function by switching the functional valence of PAK2 binding.
authors.affiliation: Thoracic Diseases Research Unit, Department of Biochemistry and Molecular Biology and Mayo Clinic Cancer Center, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Wilkes
authors.forename: Claire E
authors.initials: CE
authors.lastname: Repellin
authors.forename: Min
authors.initials: M
authors.lastname: Hong
authors.forename: Margarita
authors.initials: M
authors.lastname: Bracamonte
authors.forename: Sumedha G
authors.initials: SG
authors.lastname: Penheiter
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Borg
authors.forename: Edward B
authors.initials: EB
authors.lastname: Leof
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008954:Models, Biological; D025581:Neurofibromin 2 / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D054462:p21-Activated Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein
chemical_list: D002352:Carrier Proteins; C498804:Erbb2ip protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D025581:Neurofibromin 2; D009479:Neuropeptides; C484602:Rac1 protein, mouse; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C515909:Pak2 protein, mouse; D054462:p21-Activated Kinases; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein