Filamin is essential in actin cytoskeletal assembly mediated by p21-activated kinase 1.
The serine/threonine kinase p21-activated kinase 1 (Pak1) controls the actin cytoskeletal and ruffle formation through mechanisms that are independent of GTPase activity. Here we identify filamin FLNa as a Pak1-interacting protein through a yeast two-hybrid screen using the amino terminus of Pak1 as a bait. FLNa is stimulated by physiological signalling molecules to undergo phosphorylation by Pak1 and to interact and colocalize with endogenous Pak1 in membrane ruffles. The ruffle-forming activity of Pak1 is functional in FLNa-expressing cells but not in FLNa-deficient cells. In FLNa, the Pak1-binding site involves tandem repeat 23 in the carboxyl terminus and phosphorylation takes place on serine 2152. The FLNa-binding site in Pak1 is localized between amino acids 52 and 132 in the conserved Cdc42/Rac-interacting (CRIB) domain; accordingly, FLNa binding to the CRIB domain stimulates Pak1 kinase activity. Our results indicate that FLNa may be essential for Pak1-induced cytoskeletal reorganization and that the two-way regulatory interaction between Pak1 and FLNa may contribute to the local stimulation of Pak1 activity and its targets in cytoskeletal structures.
Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Ratna K
RK
Vadlamudi
Feng
F
Li
Liana
L
Adam
Diep
D
Nguyen
Yasutaka
Y
Ohta
Thomas P
TP
Stossel
Rakesh
R
Kumar
D000199:Actins / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D003285:Contractile Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004789:Enzyme Activation; D064448:Filamins; D049452:Green Fluorescent Proteins; D006801:Humans; D066298:In Vitro Techniques; D054461:Lim Kinases; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques; D054462:p21-Activated Kinases
D000199:Actins; D003285:Contractile Proteins; D064448:Filamins; D008164:Luminescent Proteins; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D011494:Protein Kinases; C515892:LIMK1 protein, human; D054461:Lim Kinases; C515903:PAK1 protein, human; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D020928:Mitogen-Activated Protein Kinases