HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Oh, E.-S. Articles by Couchman, J. R. Search for Related Content PubMed PubMed Citation Articles by Oh, E.-S. Articles by Couchman, J. R. Social Bookmarking                      What's this?

J Biol Chem, Vol. 273, Issue 17, 10624-10629, April 24, 1998

Syndecan-4 Proteoglycan Cytoplasmic Domain and Phosphatidylinositol 4,5-Bisphosphate Coordinately Regulate Protein Kinase C Activity

Eok-Soo Oh, Anne Woods, Ssang-Taek Lim, Anne W. Theibert, and John R. Couchman

From the Department of Cell Biology, Cell Adhesion and Matrix Research Center and  Department of Neurobiology, University of Alabama, Birmingham, Alabama 35294

Phosphatidylinositol 4,5-bisphosphate (PIP₂) is involved in the organization of the actin cytoskeleton by regulating actin-associated proteins. The transmembrane heparan sulfate proteoglycan syndecan-4 also plays a critical role in protein kinase C (PKC) signaling in the formation of focal adhesions and actin stress fibers. The cytoplasmic domain of syndecan-4 core protein directly interacts with and potentiates PKC activity, and it can directly interact with the phos- phoinositide PIP₂. We, therefore, investigated whether the interaction of inositol phosphates and inositol phospholipids with syndecan-4 could regulate PKC activity. Data from in vitro kinase assays using purified PKC show that in the absence of phosphatidylserine and diolein, PIP₂ increased the extent of autophosphorylation of PKC and partially activated it to phosphorylate both histone III-S and an epidermal growth factor receptor peptide. This activity was dose-dependent, and its calcium dependence varied with PKC isotype/source. Addition of the cytoplasmic syndecan-4 peptide, but not equivalent syndecan-1 or syndecan-2 peptides, potentiated the partial activation of PKC by PIP₂, resulting in activity greater than that observed with phosphatidylserine, diolein, and calcium. This study indicates that syndecan-4 cytoplasmic domain may bind both PIP₂ and PKC, localize them to forming focal adhesions, and potentiate PKC activity there.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati