Association ofrasGAPSH3 Binding Protein 1, G3BP1, andrasGAP¹²⁰with Integrin Containing Complexes Induced by an Adhesion Blocking Antibody

Abstract

The adhesion blocking antibody 3S3 was used to probe the regulation of R5 1 integrin mediated adhesion in K562 cells. This antibody prevented cellular adherence but it did not interfere with ligand binding by cells or purified integrin. Interaction with 3S3 induced change in the cytoskeletal organization resulting in extensive filopodia formation. The antibody also prevented ligand and anti-integrin antibody induced phosphorylation of FAK in a trans acting fashion. MS based analysis of 3S3 induced integrin containing complexes identified rasGAP SH3 binding protein 1, G3BP1, as a component of these structures. The G3BP1 binding molecule, rasGap 120 , was also identified in the complexes. Microscopic examination confirmed the recruitment of a component of cellular G3BP1 and rasGap 120 pools to sites of integrin cross-linking. G3BP1 was also observed in the 3S3 induced filopodia. In untreated cells, G3BP1 was shown to associate with submembranous regions involved in cellular polarization. Collectively, these results suggest that G3BP1 and rasGap 120 can be recruited to sites of integrin ligation where they may play a role in cytoskeletal reorganization. Such changes may result in reduced adhesive potential and account for the 3S3 effects on cellular adhesion. It should be emphasized that these results do not necessarily indicate a direct interaction of integrin with G3BP1 and rasGap 120 .

Distinct Structural Features ofCaprin-1 Mediate Its Interaction with G3BP-1 and Its Induction of Phosphorylation of Eukaryotic Translation InitiationFactor 2α, Entry to Cytoplasmic Stress Granules, and Selective Interaction with a Subset of mRNAs

“…These observations are consistent with the notion that Caprin-1/G3BP-1 RNA granules are transported in a microtubuledependent manner to sites such as the leading or trailing edges of migrating cells that are rich in F-actin and RNA (3). They are also consistent with reports that immunoprecipitates of Paxillin from focal adhesions contain Caprin-1 (9) and that G3BP-1 localized close to the membrane at areas of cell polarization and was concentrated in filopodia and sites where integrins had been cross-linked (31,37). Our observations on epithelial cells and fibroblasts extend those of Shiina et al (40), who reported that Caprin-1 was localized in presynaptic granules in the dendrites of neurons, by showing that Caprin-1-containing granules are also present in nonneuronal cells, where they are abundant and contain a significant fraction of the cytoplasmic RNA.…”

Epithelial mesenchymal transition traits in honey‐driven keratinocyte wound healing: Comparison among different honeys

“…An analysis of the phosphorylation of proteins involved in proliferation and cytoskeletal rearrangement showed that all honeys intensely activated CDK2, a cyclin‐dependent kinase, known to be involved in G1‐S transition and keratinocyte proliferation . Focal adhesion kinase (FAK) and rasGAP SH3 binding protein 1, both involved in focal complex formation and cell locomotion, were also uniformly activated by honeys. Other peptides potentially related to cytoskeletal and cell cycle dynamics showed variable patterns of activation among honeys, including vasodilator‐stimulated phosphoprotein, integrin‐β3, cdc25C, and p42/44 mitogen activated protein kinase (Table ).…”

Human U87 Astrocytoma Cell Invasion Induced by Interaction of βig-h3 with Integrin α5β1 Involves Calpain-2

“…The “function blocking” antibodies, mouse anti-human α5 mAb (P1D6) and mouse anti-human β1 mAb (3S3), neutralize binding of α5β1 to the central cell adhesion domain of fibronectin. Such reaction may result in decrease of invasion potential and MMP secretion [17]–[20]. We treated U87 cells with P1D6, 3S3, P1D6+3S3 and si-βig-h3 for 36 h, and then examined the invasive ability and the presence of MMPs.…”