title: Microtubules regulate GEF-H1 in response to extracellular matrix stiffness.
abstract: Breast epithelial cells sense the stiffness of the extracellular matrix through Rho-mediated contractility. In turn, matrix stiffness regulates RhoA activity. However, the upstream signaling mechanisms are poorly defined. Here we demonstrate that the Rho exchange factor GEF-H1 mediates RhoA activation in response to extracellular matrix stiffness. We demonstrate the novel finding that microtubule stability is diminished by a stiff three-dimensional (3D) extracellular matrix, which leads to the activation of GEF-H1. Surprisingly, activation of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway did not contribute to stiffness-induced GEF-H1 activation. Loss of GEF-H1 decreases cell contraction of and invasion through 3D matrices. These data support a model in which matrix stiffness regulates RhoA through microtubule destabilization and the subsequent release and activation of GEF-H1.
authors.affiliation: Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA. heck@wisc.edu
authors.forename: Jessica N
authors.initials: JN
authors.lastname: Heck
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Ponik
authors.forename: Maria G
authors.initials: MG
authors.lastname: Garcia-Mendoza
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Pehlke
authors.forename: David R
authors.initials: DR
authors.lastname: Inman
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Eliceiri
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Keely
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002465:Cell Movement; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005109:Extracellular Matrix / Q000378:metabolism* / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D055785:Gene Knockdown Techniques; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System; D008321:Mammary Glands, Animal / Q000166:cytology; D051379:Mice; D008870:Microtubules / Q000378:metabolism*; D055550:Protein Stability; D034622:RNA Interference; D064067:Rho Guanine Nucleotide Exchange Factors; D020742:rhoA GTP-Binding Protein / Q000378:metabolism / Q000502:physiology
chemical_list: C577356:ARHGEF2 protein, human; D020662:Guanine Nucleotide Exchange Factors; D064067:Rho Guanine Nucleotide Exchange Factors; C066737:RHOA protein, human; D048049:Extracellular Signal-Regulated MAP Kinases; D020742:rhoA GTP-Binding Protein