The Diaphanous-related Formin FHOD1 associates with ROCK1 and promotes Src-dependent plasma membrane blebbing.
Diaphanous-related formins (DRFs) mediate GTPase-triggered actin rearrangements to regulate central cellular processes, such as cell motility and cytokinesis. The DRF FHOD1 interacts with the Rho-GTPase Rac1 and mediates formation of actin stress fibers in its deregulated form; the physiologically relevant activities and molecular mechanisms of endogenous FHOD1, however, are still unknown. Here we report that FHOD1 physically associates via the N-terminal part of its FH2 domain with the central domain of ROCK1. Although FHOD1 does not affect the kinase activity of ROCK1, the DRF is an efficient substrate for phosphorylation by ROCK1. Co-expression of FHOD1 and ROCK1 results in the generation of nonapoptotic plasma membrane (PM) blebs, to which the DRF is efficiently recruited. Blebbing induced by FHOD1 and ROCK1 depends on F-actin integrity, the Rho-ROCK cascade, and Src activity and is reminiscent of the recently described PM blebs triggered by expression of Src homology 4 (SH4) domain PM targeting signals. Consistently, endogenous FHOD1 is required in SH4 domain expressing cells for efficient PM blebbing and rounded cell morphology in two-dimensional cultures or three-dimensional matrices, respectively. Efficient association of FHOD1 with ROCK1, as well as recruitment of the DRF to blebs, depends on Src activity, suggesting that the functional interaction between both proteins is regulated by Src. These results define a role for endogenous FHOD1 in SH4 domain-induced blebbing and suggest that its activity is regulated by ROCK1 in a Src-dependent manner.
Hannemann
Sebastian
S
Department of Virology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Madrid
Ricardo
R
Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), 75014 Paris, France; INSERM U567, 75014 Paris, France; Centro de Biología Molecular "Severo Ochoa," Universidad Autónoma de Madrid and Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain.
Stastna
Jana
J
Department of Virology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Kitzing
Thomas
T
Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Gasteier
Judith
J
Department of Virology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Schönichen
André
A
Abteilung Physikalische Biochemie, Max-Planck-Institut für Molekulare Physiologie, 44227 Dortmund, Germany.
Bouchet
Jerome
J
Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), 75014 Paris, France; INSERM U567, 75014 Paris, France.
Jimenez
Alberto
A
Centro de Biología Molecular "Severo Ochoa," Universidad Autónoma de Madrid and Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain.
Geyer
Matthias
M
Abteilung Physikalische Biochemie, Max-Planck-Institut für Molekulare Physiologie, 44227 Dortmund, Germany.
Grosse
Robert
R
Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
Benichou
Serge
S
Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), 75014 Paris, France; INSERM U567, 75014 Paris, France.
Fackler
Oliver T
OT
Department of Virology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany. Electronic address: oliver_fackler@med.uni-heidelberg.de.
D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D021961:Cell Membrane Structures / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D005326:Fetal Proteins / Q000235:genetics / Q000378:metabolism*; D000080865:Formins; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D022502:Stress Fibers / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*; D018909:src Homology Domains / Q000502:physiology; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
C120021:FHOD1 protein, human; D005326:Fetal Proteins; D000080865:Formins; D009687:Nuclear Proteins; C107953:RAC1 protein, human; D019061:src-Family Kinases; C515851:ROCK1 protein, human; D054460:rho-Associated Kinases; D020830:rac1 GTP-Binding Protein