title: Protein kinase B regulates T lymphocyte survival, nuclear factor kappaB activation, and Bcl-X(L) levels in vivo.
abstract: The serine/threonine kinase protein kinase B (PKB)/Akt mediates cell survival in a variety of systems. We have generated transgenic mice expressing a constitutively active form of PKB (gag-PKB) to examine the effects of PKB activity on T lymphocyte survival. Thymocytes and mature T cells overexpressing gag-PKB displayed increased active PKB, enhanced viability in culture, and resistance to a variety of apoptotic stimuli. PKB activity prolonged the survival of CD4(+)CD8(+) double positive (DP) thymocytes in fetal thymic organ culture, but was unable to prevent antigen-induced clonal deletion of thymocytes expressing the major histocompatibility complex class I-restricted P14 T cell receptor (TCR). In mature T lymphocytes, PKB can be activated in response to TCR stimulation, and peptide-antigen-specific proliferation is enhanced in T cells expressing the gag-PKB transgene. Both thymocytes and T cells overexpressing gag-PKB displayed elevated levels of the antiapoptotic molecule Bcl-X(L). In addition, the activation of peripheral T cells led to enhanced nuclear factor (NF)-kappaB activation via accelerated degradation of the NF-kappaB inhibitory protein IkappaBalpha. Our data highlight a physiological role for PKB in promoting survival of DP thymocytes and mature T cells, and provide evidence for the direct association of three major survival molecules (PKB, Bcl-X(L), and NF-kappaB) in vivo in T lymphocytes.
authors.affiliation: Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
authors.forename: R G
authors.initials: RG
authors.lastname: Jones
authors.forename: M
authors.initials: M
authors.lastname: Parsons
authors.forename: M
authors.initials: M
authors.lastname: Bonnard
authors.forename: V S
authors.initials: VS
authors.lastname: Chan
authors.forename: W C
authors.initials: WC
authors.lastname: Yeh
authors.forename: J R
authors.initials: JR
authors.lastname: Woodgett
authors.forename: P S
authors.initials: PS
authors.lastname: Ohashi
mesh_terms: D000818:Animals; D017209:Apoptosis; D002470:Cell Survival / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D015870:Gene Expression; D015750:Genes, gag; D006801:Humans; D020672:I-kappa B Proteins; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism*; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051020:bcl-X Protein; D000072000:NF-KappaB Inhibitor alpha; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt