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      Role of Phosphatidylinositol 3-Kinase and Specific Protein Kinase B Isoforms in the Suppression of Apoptosis Mediated by the Abelson Protein-tyrosine Kinase

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          Abstract

          Leukemogenic oncogenes, such as the Abelson protein-tyrosine kinases (PTK), disrupt the normal regulation of survival, proliferation, and differentiation in hemopoietic progenitor cells. In the absence of cytokines, hemopoietic progenitor cells die by apoptosis. Abl PTKs mediate suppression of this apoptotic response leading to aberrant survival. To investigate the mechanism of Abl PTK action, we have used an interleukin-3-dependent murine mast cell line that expresses a temperature-sensitive form of the v-ABL PTK, which is active at the permissive temperature of 32 degrees C and inactive at 39 degrees C. At the permissive temperature, these cells are resistant to apoptosis induced both by the withdrawal of the hemopoietic growth factor (interleukin-3) and the addition of cytotoxic drugs. We demonstrate that v-Abl associates with and stimulates activation of phosphatidylinositol 3-kinase (PI3K) and, crucially, that this activation results in enhanced cellular levels of the mass of the second messenger phosphatidylinositol-3,4,5-trisphosphate. Activation of PI3K leads to enhanced activity of PKB and increased levels of the anti-apoptotic protein Bcl-X(L). Transfection of cells with a dominant negative PKB reduces both the Abl-stimulated PKB activity and the survival effect conferred by activation of this oncogene. Thus, PI3K and PKB are required for the anti-apoptotic effects of Abl PTK.

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          Most cited references25

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          Regulation of neuronal survival by the serine-threonine protein kinase Akt.

          A signaling pathway was delineated by which insulin-like growth factor 1 (IGF-1) promotes the survival of cerebellar neurons. IGF-1 activation of phosphoinositide 3-kinase (PI3-K) triggered the activation of two protein kinases, the serine-threonine kinase Akt and the p70 ribosomal protein S6 kinase (p70(S6K)). Experiments with pharmacological inhibitors, as well as expression of wild-type and dominant-inhibitory forms of Akt, demonstrated that Akt but not p70(S6K) mediates PI3-K-dependent survival. These findings suggest that in the developing nervous system, Akt is a critical mediator of growth factor-induced neuronal survival.
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            Characterization of a 3-phosphoinositide-dependent protein kinase which phosphorylates and activates protein kinase Bα

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              Requirement for phosphatidylinositol-3 kinase in the prevention of apoptosis by nerve growth factor.

              Nerve growth factor (NGF) induces both differentiation and survival of neurons by binding to the Trk receptor protein tyrosine kinase. Although Ras is required for differentiation, it was not required for NGF-mediated survival of rat pheochromocytoma PC-12 cells in serum-free medium. However, the ability of NGF to prevent apoptosis (programmed cell death) was inhibited by wortmannin or LY294002, two specific inhibitors of phosphatidylinositol (Pl)-3 kinase. Moreover, platelet-derived growth factor (PDGF) prevented apoptosis of PC-12 cells expressing the wild-type PDGF receptor, but not of cells expressing a mutant receptor that failed to activate Pl-3 kinase. Cell survival thus appears to be mediated by a Pl-3 kinase signaling pathway distinct from the pathway that mediates differentiation.
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                Author and article information

                Journal
                Journal of Biological Chemistry
                J. Biol. Chem.
                American Society for Biochemistry & Molecular Biology (ASBMB)
                0021-9258
                1083-351X
                April 21 2000
                April 28 2000
                : 275
                : 17
                : 13142-13148
                Article
                10.1074/jbc.275.17.13142
                10777620
                a7630147-5fee-45fd-9749-0af7500e3619
                © 2000
                History

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