FMNL formins boost lamellipodial force generation.
Migration frequently involves Rac-mediated protrusion of lamellipodia, formed by Arp2/3 complex-dependent branching thought to be crucial for force generation and stability of these networks. The formins FMNL2 and FMNL3 are Cdc42 effectors targeting to the lamellipodium tip and shown here to nucleate and elongate actin filaments with complementary activities in vitro. In migrating B16-F1 melanoma cells, both formins contribute to the velocity of lamellipodium protrusion. Loss of FMNL2/3 function in melanoma cells and fibroblasts reduces lamellipodial width, actin filament density and -bundling, without changing patterns of Arp2/3 complex incorporation. Strikingly, in melanoma cells, FMNL2/3 gene inactivation almost completely abolishes protrusion forces exerted by lamellipodia and modifies their ultrastructural organization. Consistently, CRISPR/Cas-mediated depletion of FMNL2/3 in fibroblasts reduces both migration and capability of cells to move against viscous media. Together, we conclude that force generation in lamellipodia strongly depends on FMNL formin activity, operating in addition to Arp2/3 complex-dependent filament branching.
Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.|Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Frieda
F
Kage
Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
Moritz
M
Winterhoff
Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.|Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Vanessa
V
Dimchev
Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
Jan
J
Mueller
Soft Matter Physics Group, Institut für experimentelle Physik I, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany.
Tobias
T
Thalheim
Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.|Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Anika
A
Freise
Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
Stefan
S
Brühmann
Biomedical Institute, BRIC, University of Copenhagen, DK-2200 Copenhagen, Denmark.|Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Jana
J
Kollasser
Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Jennifer
J
Block
Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.|Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Georgi
G
Dimchev
Institute of Innate Immunity, Department of Structural Immunology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.
Matthias
M
Geyer
Institute of Anatomy and Vascular Biology, Westfälische Wilhelms-Universität Münster, Vesaliusweg 2-4, 48149 Münster, Germany.
Hans-Joachim
HJ
Schnittler
Biomedical Institute, BRIC, University of Copenhagen, DK-2200 Copenhagen, Denmark.
Cord
C
Brakebusch
Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Theresia E B
TE
Stradal
Cytoskeleton Dynamics and Motility Group, Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette 91198, France.
Marie-France
MF
Carlier
Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
Michael
M
Sixt
Soft Matter Physics Group, Institut für experimentelle Physik I, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany.
Josef
J
Käs
Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
Jan
J
Faix
Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.|Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
Klemens
0000-0003-4244-4198
K
Rottner
D000818:Animals; D001696:Biomechanical Phenomena; D064113:CRISPR-Cas Systems / Q000235:genetics; D002465:Cell Movement; D005347:Fibroblasts / Q000378:metabolism; D000080865:Formins; D055785:Gene Knockdown Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D041681:NIH 3T3 Cells; D010641:Phenotype; D058105:Polymerization; D011506:Proteins / Q000378:metabolism*; D011554:Pseudopodia / Q000378:metabolism* / Q000648:ultrastructure; D034622:RNA Interference
C000592815:FMNL2 protein, mouse; C570808:FMNL3 protein, mouse; D000080865:Formins; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins