Actin cytoskeletal association of cytohesin-1 is regulated by specific phosphorylation of its carboxyl-terminal polybasic domain.

Abstract

Cell adhesion mediated by integrin receptors is controlled by intracellular signal transduction cascades. Cytohesin-1 is an integrin-binding protein and guanine nucleotide exchange factor that activates binding of the leukocyte integrin leukocyte function antigen-1 to its ligand, intercellular adhesion molecule 1. Cytohesin-1 bears a carboxyl-terminal pleckstrin homology domain that aids in reversible membrane recruitment and functional regulation of the protein. Although phosphoinositide-dependent membrane attachment of cytohesin-1 is mediated primarily by the pleckstrin homology domain, this function is further strengthened by a short carboxyl-terminal polybasic amino acid sequence. We show here that a serine/threonine motif within the short polybasic stretch of cytohesin-1 is phosphorylated by purified protein kinase C delta in vitro. Furthermore, the respective residues are also found to be phosphorylated after phorbol ester stimulation in vivo. Biochemical and functional analyses show that phosphorylated cytohesin-1 is able to tightly associate with the actin cytoskeleton, and we further demonstrate that phosphorylation of the protein is required for maximal leukocyte function antigen-1-mediated adhesion of Jurkat cells to intercellular adhesion molecule 1. These data suggest that both phosphatidylinositol 3-kinase and protein kinase C-dependent intracellular pathways that stimulate beta(2)-integrin-mediated adhesion of T lymphocytes converge on cytohesin-1 as functional integrator.

• Authors: H Dierks, J Kolanus, W Kolanus
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 276 Issue 40 Pg. 37472-81 (Oct 05 2001) ISSN: 0021-9258 [Print] United States
• PMID: 11438522 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Actins
• Carcinogens
• Cell Adhesion Molecules
• Guanine Nucleotide Exchange Factors
• cytohesin-1
• Intercellular Adhesion Molecule-1
• Tetradecanoylphorbol Acetate

Topics

• Actins (metabolism)
• Animals
• COS Cells
• Carcinogens (pharmacology)
• Cell Adhesion (drug effects)
• Cell Adhesion Molecules (chemistry, metabolism, physiology)
• Cytoskeleton (drug effects, metabolism)
• Guanine Nucleotide Exchange Factors
• Humans
• Intercellular Adhesion Molecule-1 (metabolism)
• Jurkat Cells
• Phosphorylation (drug effects)
• Protein Structure, Tertiary
• Tetradecanoylphorbol Acetate (pharmacology)