Teodorof Carmen, Bae Jeom Il, Kim Seon-Myung, Oh Hye Jin, Kang Yong Seok, Choi Jeonghoon, Chun Jang-Soo, Song Woo Keun
Bio Imaging Research Center, Cell Dynamics Research Center, Department of Life Science, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, South Korea.
Exp Cell Res. 2009 Aug 15;315(14):2410-9. doi: 10.1016/j.yexcr.2009.05.010. Epub 2009 May 19.
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.
SPIN90是肌动蛋白细胞骨架组织的关键调节因子。利用BioGRID（β）数据库（相互作用数据集通用储存库），我们鉴定出IRSp53是SPIN90的结合伴侣，并证实通过SPIN90富含脯氨酸的结构域（PRD）与IRSp53的SH3结构域直接结合介导了SPIN90-IRSp53复合物在体内的形成。SPIN90和IRSp53积极协作以介导Rac激活，并且在COS-7细胞中共表达SPIN90和IRSp53导致在细胞前沿形成SPIN90-IRSp53复合物。血小板衍生生长因子（PDGF）处理诱导SPIN90和IRSp53在膜突出部位强烈共定位。在这种PDGF诱导的突出部位，使用小干扰RNA（siRNA）敲低SPIN90蛋白可显著减少片状伪足样突出以及IRSp53在这些部位的定位。最后，SPIN90的PRD对SPIN90-IRSp53结合的竞争性抑制显著减少了褶皱形成，进一步表明SPIN90在与细胞运动相关的膜突出形成中起关键作用。
