title: Interplay between components of a novel LIM kinase-slingshot phosphatase complex regulates cofilin.
abstract: Slingshot (SSH) phosphatases and LIM kinases (LIMK) regulate actin dynamics via a reversible phosphorylation (inactivation) of serine 3 in actin-depolymerizing factor (ADF) and cofilin. Here we demonstrate that a multi-protein complex consisting of SSH-1L, LIMK1, actin, and the scaffolding protein, 14-3-3zeta, is involved, along with the kinase, PAK4, in the regulation of ADF/cofilin activity. Endogenous LIMK1 and SSH-1L interact in vitro and co-localize in vivo, and this interaction results in dephosphorylation and downregulation of LIMK1 activity. We also show that the phosphatase activity of purified SSH-1L is F-actin dependent and is negatively regulated via phosphorylation by PAK4. 14-3-3zeta binds to phosphorylated slingshot, decreases the amount of slingshot that co-sediments with F-actin, but does not alter slingshot activity. Here we define a novel ADF/cofilin phosphoregulatory complex and suggest a new mechanism for the regulation of ADF/cofilin activity in mediating changes to the actin cytoskeleton.
authors.affiliation: The Walter & Eliza Hall Institute of Medical Research, Victoria, Australia.
authors.forename: Juliana
authors.initials: J
authors.lastname: Soosairajah
authors.forename: Sankar
authors.initials: S
authors.lastname: Maiti
authors.forename: O'neil
authors.initials: O
authors.lastname: Wiggan
authors.forename: Patrick
authors.initials: P
authors.lastname: Sarmiere
authors.forename: Nathalie
authors.initials: N
authors.lastname: Moussi
authors.forename: Boris
authors.initials: B
authors.lastname: Sarcevic
authors.forename: Rashmi
authors.initials: R
authors.lastname: Sampath
authors.forename: James R
authors.initials: JR
authors.lastname: Bamburg
authors.forename: Ora
authors.initials: O
authors.lastname: Bernard
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002645:Chickens; D051345:Destrin; D006801:Humans; D066298:In Vitro Techniques; D054461:Lim Kinases; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes; D009474:Neurons / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054462:p21-Activated Kinases
chemical_list: D048948:14-3-3 Proteins; D051339:Actin Depolymerizing Factors; D000199:Actins; C495824:DSTN protein, human; D051345:Destrin; D008840:Microfilament Proteins; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases; C116367:PAK4 protein, human; C515892:LIMK1 protein, human; D054461:Lim Kinases; C515894:Limk1 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D010749:Phosphoprotein Phosphatases; C484329:SSH1 protein, human