Initiation of lamellipodia and ruffles involves cooperation between mDia1 and the Arp2/3 complex.
Protrusion of lamellipodia and ruffles requires polymerization of branched actin filaments by the Arp2/3 complex. Although regulation of Arp2/3 complex activity has been extensively investigated, the mechanism of initiation of lamellipodia and ruffles remains poorly understood. Here, we show that mDia1 acts in concert with the Arp2/3 complex to promote initiation of lamellipodia and ruffles. We find that mDia1 is an epidermal growth factor (EGF)-regulated actin nucleator involved in membrane ruffling using a combination of knockdown and rescue experiments. At the molecular level, mDia1 polymerizes linear actin filaments, activating the Arp2/3 complex, and localizes within nascent and mature membrane ruffles. We employ functional complementation experiments and optogenetics to show that mDia1 cooperates with the Arp2/3 complex in initiating lamellipodia and ruffles. Finally, we show that genetic and pharmacological interference with this cooperation hampers ruffling and cell migration. Thus, we propose that the lamellipodium- and ruffle-initiating machinery consists of two actin nucleators that act sequentially to regulate membrane protrusion and cell migration.
Division of Molecular Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
Tadamoto
T
Isogai
Division of Molecular Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
Rob
R
van der Kammen
Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
Daniela
D
Leyton-Puig
Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
Katarzyna M
KM
Kedziora
Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands.
Kees
K
Jalink
Division of Molecular Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam 1066 CX, The Netherlands m.innocenti@nki.nl.
Metello
M
Innocenti
D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D021961:Cell Membrane Structures / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D000080865:Formins; D006367:HeLa Cells; D006801:Humans; D011554:Pseudopodia / Q000235:genetics / Q000378:metabolism*
D051376:Actin-Related Protein 2-3 Complex; D048868:Adaptor Proteins, Signal Transducing; C108962:DIAPH1 protein, human; D000080865:Formins
Actin; Arp2/3; Cell migration; Lamellipodia; Ruffles; mDia1