SPIN90-IRSp53 complex participates in Rac-induced membrane ruffling

• Published in: Experimental cell research 2009-08, Vol.315 (14), p.2410-2419
• Main Authors: Teodorof, Carmen, Bae, Jeom Il, Kim, Seon-Myung, Oh, Hye Jin, Kang, Yong Seok, Choi, Jeonghoon, Chun, Jang-Soo, Song, Woo Keun
• Format: Article
• Language: English
• Subjects: Actin; Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Binding sites; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell Movement - physiology; Cell Surface Extensions; Cellular biology; Cercopithecus aethiops; COS Cells; Cytoskeleton; Gene Knockdown Techniques; Genetic Vectors - metabolism; Humans; IRSp53; Membrane ruffling; Membranes; Muscle Proteins - genetics; Muscle Proteins - metabolism; Nerve Tissue Proteins - metabolism; Platelet-Derived Growth Factor - pharmacology; Proteins; rac GTP-Binding Proteins - metabolism; Rac1; RNA, Small Interfering - metabolism; SPIN90; Transfection
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2009.05.010

SPIN90 is a key regulator of actin cytoskeletal organization. Using the BioGRID beta database (General Repository for Interaction Datasets), we identified IRSp53 as a binding partner of SPIN90, and confirmed the in vivo formation of a SPIN90–IRSp53 complex mediated through direct association of the proline-rich domain (PRD) of SPIN90 with the SH3 domain of IRSp53. SPIN90 and IRSp53 positively cooperated to mediate Rac activation, and co-expression of SPIN90 and IRSp53 in COS-7 cells led to the complex formation of SPIN90-IRSp53 in the leading edge of cells. PDGF treatment induced strong colocalization of SPIN90 and IRSp53 at membrane protrusions. Within such PDGF-induced protrusions, knockdown of SPIN90 protein using siRNA significantly reduced lamellipodia-like protrusions as well as localization of IRSp53 at those sites. Finally, competitive inhibition of SPIN90-IRSp53 binding by SPIN90 PRD dramatically reduced ruffle formation, further suggesting that SPIN90 plays a key role in the formation of the membrane protrusions associated with cell motility.