title: Arp2/3 inhibition induces amoeboid-like protrusions in MCF10A epithelial cells by reduced cytoskeletal-membrane coupling and focal adhesion assembly.
abstract: Here we demonstrate that Arp2/3 regulates a transition between mesenchymal and amoeboid protrusions in MCF10A epithelial cells. Using genetic and pharmacological means, we first show Arp2/3 inhibition impairs directed cell migration. Arp2/3 inhibition results in a dramatically impaired cell adhesion, causing deficient cell attachment and spreading to ECM as well as an 8-fold decrease in nascent adhesion assembly at the leading edge. While Arp2/3 does not play a significant role in myosin-dependent adhesion growth, mature focal adhesions undergo large scale movements against the ECM suggesting reduced coupling to the ECM. Cell edge protrusions occur at similar rates when Arp2/3 is inhibited but their morphology is dramatically altered. Persistent lamellipodia are abrogated and we observe a markedly increased incidence of blebbing and unstable pseuodopods. Micropipette-aspiration assays indicate that Arp2/3-inhibited cells have a weak coupling between the cell cortex and the plasma membrane, and suggest a potential mechanism for increased pseudopod and bleb formation. Pseudopods are not sensitive to reduced in formin or myosin II activity. Collectively, these results indicate that Arp2/3 is not necessary for rapid protrusion of the cell edge but plays a crucial role in assembling focal adhesions required for its stabilization.
authors: Institute for Biophysical Dynamics, University of Chicago Medical Center, Chicago, Illinois, United States of America.
authors: Yvonne
authors: Y
authors: Beckham
authors: Section of Hematology, Oncology and Stem Cell Transplantation, Department of Pediatrics, University of Chicago Medical Center, Chicago, Illinois, United States of America.
authors: Robert J
authors: RJ
authors: Vasquez
authors: James Franck Institute, University of Chicago, Chicago, Illinois, United States of America; Department of Physics, University of Chicago, Chicago, Illinois, United States of America.
authors: Jonathan
authors: J
authors: Stricker
authors: James Franck Institute, University of Chicago, Chicago, Illinois, United States of America; Department of Physics, University of Chicago, Chicago, Illinois, United States of America.
authors: Kareem
authors: K
authors: Sayegh
authors: Laboratoire Physico-Chimie, Institut Curie, Centre de Recherche, Paris, France; Laboratoire Analyse et Modélisation pour la Biologie et l' Environnement, Université d'Evry Val d'Essonne, Evry, France.
authors: Clement
authors: C
authors: Campillo
authors: Institute for Biophysical Dynamics, University of Chicago Medical Center, Chicago, Illinois, United States of America; James Franck Institute, University of Chicago, Chicago, Illinois, United States of America; Department of Physics, University of Chicago, Chicago, Illinois, United States of America.
authors: Margaret L
authors: ML
authors: Gardel
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D022081:Cell Surface Extensions; D003599:Cytoskeleton / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D024462:Myosin Type II / Q000378:metabolism; D016566:Organoselenium Compounds / Q000494:pharmacology; D017646:Organosilicon Compounds / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; C585054:CK-869; D016566:Organoselenium Compounds; D017646:Organosilicon Compounds; D034741:RNA, Small Interfering; D024462:Myosin Type II