The Lipid Products of Phosphoinositide 3-Kinase Increase Cell Motility through Protein Kinase C

doi:10.1074/jbc.272.10.6465

The Lipid Products of Phosphoinositide 3-Kinase Increase Cell Motility through Protein Kinase C*

From the Department of Medicine, Divisions of ^‡ Nephrology and
^§ Signal Transduction, Beth Israel Deaconess Medical Center and the
^¶ Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02215, the
^∥ Divisions of Experimental Medicine and Hematology-Oncology, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02215, the
** Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75325 and the
^‡‡ Division of Medicinal Chemistry and Pharmaceutics, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40506-0286

^§ To whom correspondence should be addressed:
Div. of Nephrology, Dana 517, Beth Israel Hospital, 330 Brookline Ave., Boston, MA 02215.
Tel.: 617-667-2147; Fax: 617-667-5276.

Abstract

Phosphoinositide 3-kinase has been implicated as an activator of cell motility in a variety of recent studies, yet the role of its lipid product, phosphatidylinositol 1,4,5-trisphosphate (PtdIns-3,4,5-P₃), has yet to be elucidated. In this study, three independent preparations of PtdIns-3,4,5-P₃ were found to increase the motility of NIH 3T3 cells when examined utilizing a microchemotaxis chamber. Dipalmitoyl L-α-phosphatidyl-D-myo-inositol 3,4,5-triphosphate (Di-C₁₆-PtdIns-3,4,5-P₃) also produced actin reorganization and membrane ruffling. Cells pretreated with 12-O-tetradecanoylphorbol-13-acetate to cause down-regulation of protein kinase C (PKC) exhibited complete inhibition of cell motility induced by Di-C₁₆-PtdIns-3,4,5-P₃. These results are consistent with previous observations that PtdIns-3,4,5-P₃ activates Ca²⁺-independent PKC isoforms in vitro and in vivo and provide the first demonstration of an in vivo role for the lipid products of the phosphoinositide 3-kinase. PtdIns-3,4,5-P₃ appears to directly initiate cellular motility via activation of a PKC family member.

Footnotes

↵* This work was supported in part by National Institutes of Health Grant DK48871. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PDGF

platelet-derived growth factor

HGF

hepatocyte growth factor

PI

phosphoinositide

PtdIns

phosphatidylinositol

PtdSer

phosphatidylserine

DAG

diacylglycerol

TPA

12-O-tetradecanoylphorbol-13-acetate.
↵²P. Janmey, unpublished results.
- Received September 24, 1996.
- Revision received December 16, 1996.