Abstract
Interleukin-2 (IL-2) stimulates proliferation of T lymphocytes and is involved in the activation of both natural killer and lymphokine-activated killer precursor cells. The intracellular messengers which mediate IL-2-dependent events have not yet been identified. IL-2 receptor is not a protein-tyrosine kinase. Activation of a cellular protein-tyrosine kinase and direct association of a protein-tyrosine kinase activity with the IL-2 receptor occurs within minutes of IL-2 stimulation. We investigated the activation of phosphatidylinositol 3-kinase (PI 3-kinase) in IL-2-mediated signal transduction using the IL-2-dependent murine T-cell line, CTLL-2, and human phytohemagglutinin-stimulated peripheral blood lymphocytes (phytohemagglutinin blasts). Within a minute following stimulation of these cells with IL-2, PI 3-kinase activity could be detected in antiphosphotyrosine (anti-P-Tyr) antibody immunoprecipitates. IL-2 triggered a direct association of PI 3-kinase with the IL-2 receptor as detected in immunoprecipitates using anti-IL-2 receptor beta chain antibody. In vivo labeled CTLL-2 cells have a time-dependent increase in D-3-phosphorylated polyphosphoinositides following stimulation with IL-2. This is the first group of second messengers identified in IL-2-mediated signal transduction.
Highlights
(Kdlo-’ M) and has a 286-amino acid intracytoplasmic domain
I'HA hlasts were stimulnted with human recomhinant IL-2 for the chain [35]before and after stimulationof intact cells withIL
The datapresented here suggests that IL-2-dependent signaltransduction involves activation of PI 3-kinase
Summary
(Kdlo-’ M) and has a 286-amino acid intracytoplasmic domain. A restricted 46-amino acid segment of this domain is essential for IL-2-mediated signal transduction [9]. Several transmembrane growth factor receptors, which act as ligand-activated protein-tyrosine kinases, have IL-2 receptor is not a protein-tyrosine kinase.
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