Rac regulates integrin-mediated spreading and increased adhesion of T lymphocytes

D'Souza-Schorey, C., Boettner, B., Van Aelst, L. (July 1998) Rac regulates integrin-mediated spreading and increased adhesion of T lymphocytes. Molecular and Cellular Biology, 18 (7). pp. 3936-3946. ISSN 0270-7306

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URL: http://www.ncbi.nlm.nih.gov/pubmed/9632778

Abstract

Leukocyte adhesion to the extracellular matrix (ECM) is tightly controlled and is vital for the immune response. Circulating lymphocytes leave the bloodstream and adhere to ECM components at sites of inflammation and lymphoid tissues. Mechanisms for regulating T-lymphocyte-ECM adhesion include (i) an alteration in the affinity of cell surface integrin receptors for their extracellular ligands and (ii) an alteration of events following postreceptor occupancy (e.g., cell spreading). Whereas H-Ras and R-Ras were previously shown to affect T-cell adhesion by altering the affinity state of the integrin receptors, no signaling molecule has been identified for the second mechanism. In this study, we demonstrated that expression of an activated mutant of Rac triggered dramatic spreading of T cells and their increased adhesion on immobilized fibronectin in an integrin-dependent manner. This effect was not mimicked by expression of activated mutant forms of Rho, Cdc42, H-Ras, of ARF6, indicating the unique role of pac in this event. The Rac-induced spreading was accompanied by specific cytoskeletal rearrangements; Also, a clustering of integrins at sites of cell adhesion and at the peripheral edges of spread cells was observed. We demonstrate that expression of RacV12 did not alter the level of expression of cell surface integrins or the affinity state of the integrin receptors. Moreover, our results indicate that Rac plays a role in the regulation of T-cell adhesion by a mechanism involving cell spreading, rather than by altering the level of expression or the affinity of the integrin receptors. Furthermore, we show that the Rac-mediated signaling pathway leading to spreading of T lymphocytes did not require activation of c-Jun kinase, serum response factor, or pp70(S6) (kinase) but appeared to involve a phospholipid kinase.

Item Type: Paper
Uncontrolled Keywords: ACTIN STRESS FIBERS CELL-ADHESION PHOSPHATIDYLINOSITOL 4-KINASE MONOCLONAL-ANTIBODY RHO FIBRONECTIN COMPLEXES PROTEINS KINASE CDC42
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > Rac
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > integrin
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
CSHL Authors:
Communities: CSHL labs > Van Aelst lab
Depositing User: Matt Covey
Date: July 1998
Date Deposited: 18 Dec 2013 21:52
Last Modified: 18 Dec 2013 21:52
PMCID: PMC108978
Related URLs:
URI: http://repository.cshl.edu/id/eprint/29108

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