Interplay between components of a novel LIM kinase-slingshot phosphatase complex regulates cofilin

• Published in: The EMBO journal 2005-02, Vol.24 (3), p.473-486
• Main Authors: Soosairajah, Juliana, Maiti, Sankar, Wiggan, O'Neil, Sarmiere, Patrick, Moussi, Nathalie, Sarcevic, Boris, Sampath, Rashmi, Bamburg, James R, Bernard, Ora
• Format: Article
• Language: English
• Subjects: 14-3-3; 14-3-3 Proteins - chemistry; 14-3-3 Proteins - genetics; 14-3-3 Proteins - metabolism; Actin Depolymerizing Factors; Actins - metabolism; ADF/cofilin; Animals; Binding Sites; Cell Line; Chickens; Destrin; EMBO05; EMBO37; Humans; In Vitro Techniques; Inactivation; Lim Kinases; LIMK1; Microfilament Proteins - chemistry; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Models, Biological; Multiprotein Complexes; Neurons - metabolism; p21-Activated Kinases; PAK4; Phosphoprotein Phosphatases - chemistry; Phosphoprotein Phosphatases - genetics; Phosphoprotein Phosphatases - metabolism; Protein Kinases - chemistry; Protein Kinases - genetics; Protein Kinases - metabolism; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Rats; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Slingshot
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7600543

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, 14‐3‐3ζ, 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. 14‐3‐3ζ 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.