Sep 1, 1994

Activation of phosphatidylinositol-3 kinase by ligation of the interleukin-7 receptor is dependent on protein tyrosine kinase activity

Blood
H DadiC M Roifman

Abstract

Ligation of the interleukin-7 receptor (IL-7R) results in a rapid phosphorylation of tyrosine residues on multiple substrates. In addition, we have recently shown that the IL-7R mediates activation of phosphatidylinositol-3 (PI-3) kinase. Because PI-3 kinase activity can be immunoprecipitated with antiphosphotyrosine antibodies in most receptor systems studied, it has been examined that either PI-3 kinase or an associated protein become tyrosine-phosphorylated after ligand binding. We studied here the possibility that PI-3 kinase, which is directly linked to mitogenic responses in growth factor receptors, is tyrosine-phosphorylated after stimulation of the IL-7R. Using anti-p85 alpha or anti-p85 beta antibodies raised against the p85 subunit of PI-3 kinase for immunoprecipitation and subsequent blotting with antiphosphotyrosine clearly shows that IL-7-stimulated human precursor cells contain both p85 alpha and p85 beta proteins phosphorylated on tyrosine residues. Specific protein tyrosine kinase inhibitors such as tyrphostin AG-490 block total cell lysate phosphorylation and tyrosine phosphorylation on p85. Similar concentrations of this inhibitor also block in vitro and in vivo PI-3 kinase activity suggesting that this enzyme...Continue Reading

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Mentioned in this Paper

IL7R
Leukemia, Lymphocytic, Acute, L2
T-Lymphocyte
Leukocyte Differentiation Antigens, Human
Interleukin-7
Phosphatidylinositol 3-Kinases
IL7
Proteins, Recombinant DNA
3,4-dihydroxy-alpha-cyanothiocinnamide, (E)-isomer
B-Lymphocytes

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