A Tyrosine Kinase Signaling Pathway Accounts for the Majority of Phosphatidylinositol 3,4,5-Trisphosphate Formation in Chemoattractant-stimulated Human Neutrophils

doi:10.1074/jbc.271.41.25204

A Tyrosine Kinase Signaling Pathway Accounts for the Majority of Phosphatidylinositol 3,4,5-Trisphosphate Formation in Chemoattractant-stimulated Human Neutrophils*

From the Departments of ^‡ Immunology and
^″ Cell Biology, The Scripps Research Institute, La Jolla, California 92037, the
^¶ Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, and the
^∥ Department of Medicine, University of California, San Diego, La Jolla, California 92037

^§ To whom correspondence should be addressed:
University of California, San Diego, The Whittier Inst., 9894 Genesee Ave., La Jolla, CA 92037
. Tel.: 619-622-8441; Fax: 619-558-3495.
^‴ To whom correspondence should be addressed:
Dept. of Immunology-IMM14, The Scripps Research Inst., 10550 N. Torrey Pines Rd., La Jolla, CA 92037
. Tel.: 619-554-8217; Fax: 619-554-8218.

Abstract

The signaling pathway leading from G protein-coupled chemoattractant receptors to the generation of oxidants by NADPH oxidase in human neutrophils requires the formation of the lipid mediator phosphatidylinositol 3,4,5-trisphosphate (PIP₃). Two mechanisms through which PIP₃ can be generated have been described in human leukocytes. One pathway involves the coupling of the src-related tyrosine kinase Lyn to the “classical” p85/p110 form of phosphatidylinositol 3-kinase. The second paradigm utilizes a novel form of phosphatidylinositol 3-kinase whose activity is directly regulated by G protein βγ subunits. In this paper, we show that formation of PIP₃ in chemoattractant-stimulated neutrophils is substantially attenuated by inhibitors that specifically block tyrosine kinase activity. These data suggest that the Lyn activation pathway plays a major role in the formation of this important lipid messenger during chemoattractant stimulation of human neutrophils.

Footnotes

↵* This work was supported by National Institutes of Health Grants GM44428 and GM39434 (to G. M. B.), DK47240 (to A. T. K.), and AI36357 (to E. R. P.) and a PhRMA Foundation Research Starter grant (to A. S.), as well as a Miles and Shirley Fitterman Research Award (to A. T. K.). This is publication 10100-IMM from The Scripps Research Institute. 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:

PI3K

phosphatidylinositol 3-kinase

PIP₃

phosphatidylinositol 3,4,5-trisphosphate

fMLP

formylmethionylleucylphenylalanine.
- Received May 25, 1996.
- Revision received July 18, 1996.