Characterization of N-WASP in cell-adhesion and regulation of filopodia induction through WIREIRSP53 complex.

Abstract

The actin cytoskeleton, made of polymerized actin together with the actin associated proteins, plays a critical role in many cellular processes, including cell adhesion and cell motility. The Arp2/3 complex, made up of two actin related proteins, promotes actin polymerization by providing the nucleus. The Arp2/3 complex is active ated by the WASP family of proteins: WASP, N-WASP, WAVE1, WAVE2, and WAVE3. N-WASP (Neural Wiskott Aldrich Syndrome Protein) interacts with the mammalian verprolin family of proteins, W1P (WASP Interacting Protein), CR16 (Corticoid Regulated), WIRE (WIp-RElated) and regulates the actin cytoskeleton. N-WASP promotes the formation of actin-rich structures such as filopodia which plays critical roles in cell adhesion and cell motility. Analysis of the adhesion properties of NWASP+/+ and N-WASP-/- mouse embryonic fibroblasts to extracellular matrix proteins revealed that N-WASP is critical for cell adhesion to fibronectin. There was no significant difference in the localization of paxillin in the two cell lines, however the Vinculin patches in WASP+/+ cells were thicker and more prominent than those in N-WASP-/- cells. The ß1 integrins in N-WASP+/ cells were found in large clusters, while ß1 integrins were more dispersed in N-WASP-/- cells. The N-WASP-/- cells migrated more rapidly than N-WASP+/+ cells in a scratch migration assay. Thus, the data suggest that N-WASP deficiency leads to reduced adhesion to fibronectin and increased cell motility.