LCK-phosphorylated human killer cell-inhibitory receptors recruit and activate phosphatidylinositol 3-kinase

LCK-phosphorylated human killer cell-inhibitory receptors recruit and activate phosphatidylinositol 3-kinase

^*The Immunology Program, Memorial Sloan-Kettering Cancer Center, and ^†Division of Rheumatology, Hospital for Special Surgery, Cornell University Medical Center, New York, NY 10021; and ^‡Department of Genetics, Harvard Medical School and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114

Communicated by Max D. Cooper, University of Alabama at Birmingham, Birmingham, AL (received for review April 9, 1998)

Abstract

HLA-specific killer cell inhibitory receptors (KIR) are thought to impede natural killer (NK) and T cell activation programs through recruitment of the SH2 domain-containing tyrosine phosphatases, SHP-1 and SHP-2, to their cytoplasmic tails (CYT). To identify other SH2 domain-containing proteins that bind KIR CYT, we used the recently described yeast two-bait interaction trap and a modified version of this system, both of which permit tyrosine phosphorylation of bait proteins. Using these systems, we show that KIR CYT, once phosphorylated by the src-family tyrosine kinase LCK, additionally bind the p85α regulatory subunit of phosphatidylinositol (PI) 3-kinase. Furthermore, we show that in an NK cell line, NK3.3, cross-linking of KIR results in recruitment of p85α to KIR and activation of PI 3-kinase lipid kinase activity. One consequence of KIR coupling to PI 3-kinase is downstream activation of the antiapoptotic protein kinase AKT. Therefore, in addition to providing negative signals, KIR may also contribute positive signals for NK and T cell growth and/or survival.

Footnotes

↵ § Present address: Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
↵ ¶ Present address: The Molecular Sciences Institute, Berkeley, CA 94704.
↵ ‖ To whom reprint requests should be addressed at: Division of Rheumatology, Research Laboratory 317, Hospital for Special Surgery, Cornell University Medical Center, 535 East 70th St., New York, NY 10021. e-mail:kingp{at}hss.edu.
ABBREVIATIONS:

NK,

natural killer;

KIR,

killer cell inhibitory receptors;

ITIM,

immunoreceptor tyrosine-based inhibitory motif;

PTK,

protein tyrosine kinase;

PI,

phosphatidylinositol;

PTPase,

protein tyrosine phosphatase;

TA,

transcriptional activator;

CYT,

cytoplasmic tail;

GAM,

goat anti-mouse immunoglobulin;

MHC,

major histocompatibility complex;

HRP,

horseradish peroxidase;

PMA,

phorbol 12-myristate 13-acetate;

LIR,

leukocyte immunoglobulin-like receptor;

LAIR,

leukocyte-associated immunoglobulin-like receptor