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.
Vadlamudi
Ratna K
RK
Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Li
Feng
F
Adam
Liana
L
Nguyen
Diep
D
Ohta
Yasutaka
Y
Stossel
Thomas P
TP
Kumar
Rakesh
R
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