scholarly journals CD28-dependent Activation of Protein Kinase B/Akt Blocks Fas-mediated Apoptosis by Preventing Death-inducing Signaling Complex Assembly

2002 ◽  
Vol 196 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Russell G. Jones ◽  
Alisha R. Elford ◽  
Michael J. Parsons ◽  
Linda Wu ◽  
Connie M. Krawczyk ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Protein Kinase ◽  
Cell Survival ◽  
Protein Kinase B ◽  
Active Form ◽  
Apoptosis Pathway ◽  
Signaling Complex ◽  
T Cell Survival

The T cell costimulatory molecule CD28 is important for T cell survival, yet both the signaling pathways downstream of CD28 and the apoptotic pathways they antagonize remain poorly understood. Here we demonstrate that CD4+ T cells from CD28-deficient mice show increased susceptibility to Fas-mediated apoptosis via a phosphatidylinositol 3-kinase (PI3K)-dependent pathway. Protein kinase B (PKBα/Akt1) is an important serine/threonine kinase that promotes survival downstream of PI3K signals. To understand how PI3K-mediated signals downstream of CD28 contribute to T cell survival, we examined Fas-mediated apoptosis in T cells expressing an active form of PKBα. Our data demonstrate that T cells expressing active PKB are resistant to Fas-mediated apoptosis in vivo and in vitro. PKB transgenic T cells show reduced activation of caspase-8, BID, and caspase-3 due to impaired recruitment of procaspase-8 to the death-inducing signaling complex (DISC). Similar alterations are seen in T cells from mice which are haploinsufficient for PTEN, a lipid phosphatase that regulates phosphatidylinositol-3,4,5-trisphosphate (PIP3) and influences PKBα activity. These findings provide a novel link between CD28 and an important apoptosis pathway in vivo, and demonstrate that PI3K/PKB signaling prevents apoptosis by inhibiting DISC assembly.

scholarly journals Combined Deficiency of p50 and cRel in CD4+ T Cells Reveals an Essential Requirement for Nuclear Factor κB in Regulating Mature T Cell Survival and In Vivo Function

2003 ◽  
Vol 197 (7) ◽  
pp. 861-874 ◽  
Author(s):  
Ye Zheng ◽  
Monika Vig ◽  
Jesse Lyons ◽  
Luk Van Parijs ◽  
Amer A. Beg
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Cd4 T Cells ◽  
Cell Function ◽  
Nuclear Factor ◽  
T Cell Function ◽  
T Cell Survival

Signaling pathways involved in regulating T cell proliferation and survival are not well understood. Here we have investigated a possible role of the nuclear factor (NF)-κB pathway in regulating mature T cell function by using CD4+ T cells from p50−/− cRel−/− mice, which exhibit virtually no inducible κB site binding activity. Studies with these mice indicate an essential role of T cell receptor (TCR)-induced NF-κB in regulating interleukin (IL)-2 expression, cell cycle entry, and survival of T cells. Our results further indicate that NF-κB regulates TCR-induced expression of antiapoptotic Bcl-2 family members. Strikingly, retroviral transduction of CD4+ T cells with the NF-κB–inducing IκB kinase β showed that NF-κB activation is not only necessary but also sufficient for T cell survival. In contrast, our results indicate a lack of involvement of NF-κB in both IL-2 and Akt-induced survival pathways. In vivo, p50−/− cRel−/− mice showed impaired superantigen-induced T cell responses as well as decreased numbers of effector/memory and regulatory CD4+ T cells. These findings provide the first demonstration of a role for NF-κB proteins in regulating T cell function in vivo and establish a critically important function of NF-κB in TCR-induced regulation of survival.

scholarly journals Protein Kinase B Regulates T Lymphocyte Survival, Nuclear Factor κb Activation, and Bcl-XL Levels in Vivo

2000 ◽  
Vol 191 (10) ◽  
pp. 1721-1734 ◽  
Author(s):  
Russell G. Jones ◽  
Michael Parsons ◽  
Madeleine Bonnard ◽  
Vera S.F. Chan ◽  
Wen-Chen Yeh ◽  
...  
Keyword(s):  
T Cells ◽  
Protein Kinase ◽  
T Lymphocytes ◽  
T Lymphocyte ◽  
Protein Kinase B ◽  
Active Form ◽  
Nuclear Factor ◽  
Clonal Deletion ◽  
Lymphocyte Survival

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-XL. In addition, the activation of peripheral T cells led to enhanced nuclear factor (NF)-κB activation via accelerated degradation of the NF-κB inhibitory protein IκBα. 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-XL, and NF-κB) in vivo in T lymphocytes.

scholarly journals The Pim kinases control rapamycin-resistant T cell survival and activation

2005 ◽  
Vol 201 (2) ◽  
pp. 259-266 ◽  
Author(s):  
Casey J. Fox ◽  
Peter S. Hammerman ◽  
Craig B. Thompson
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Growth And Survival ◽  
Pim Kinases ◽  
T Cell Survival

Although Pim-1 or Pim-2 can contribute to lymphoid transformation when overexpressed, the physiologic role of these kinases in the immune response is uncertain. We now report that T cells from Pim-1−/−Pim-2−/− animals display an unexpected sensitivity to the immunosuppressant rapamycin. Cytokine-induced Pim-1 and Pim-2 promote the rapamycin-resistant survival of lymphocytes. The endogenous function of the Pim kinases was not restricted to the regulation of cell survival. Like the rapamycin target TOR, the Pim kinases also contribute to the regulation of lymphocyte growth and proliferation. Although rapamycin has a minimal effect on wild-type T cell expansion in vitro and in vivo, it completely suppresses the response of Pim-1−/−Pim-2−/− cells. Thus, endogenous levels of the Pim kinases are required for T cells to mount an immune response in the presence of rapamycin. The existence of a rapamycin-insensitive pathway that regulates T cell growth and survival has important implications for understanding how rapamycin functions as an immunomodulatory drug and for the development of complementary immunotherapeutics.

scholarly journals CD4+ and CD8+ T Cell Survival Is Regulated Differentially by Protein Kinase Cθ, c-Rel, and Protein Kinase B

2007 ◽  
Vol 178 (5) ◽  
pp. 2932-2939 ◽  
Author(s):  
Samuel D. Saibil ◽  
Russell G. Jones ◽  
Elissa K. Deenick ◽  
Nicole Liadis ◽  
Alisha R. Elford ◽  
...  
Keyword(s):  
T Cell ◽  
Protein Kinase ◽  
Cell Survival ◽  
Protein Kinase B ◽  
Cd8 T Cell ◽  
T Cell Survival

scholarly journals DOCK8 deficiency impairs CD8 T cell survival and function in humans and mice

2011 ◽  
Vol 208 (11) ◽  
pp. 2305-2320 ◽  
Author(s):  
Katrina L. Randall ◽  
Stephanie S.-Y. Chan ◽  
Cindy S. Ma ◽  
Ivan Fung ◽  
Yan Mei ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Cd8 T Cells ◽  
Cell Function ◽  
Viral Infections ◽  
Cd8 T Cell ◽  
T Cell Survival ◽  
And Function

In humans, DOCK8 immunodeficiency syndrome is characterized by severe cutaneous viral infections. Thus, CD8 T cell function may be compromised in the absence of DOCK8. In this study, by analyzing mutant mice and humans, we demonstrate a critical, intrinsic role for DOCK8 in peripheral CD8 T cell survival and function. DOCK8 mutation selectively diminished the abundance of circulating naive CD8 T cells in both species, and in DOCK8-deficient humans, most CD8 T cells displayed an exhausted CD45RA+CCR7− phenotype. Analyses in mice revealed the CD8 T cell abnormalities to be cell autonomous and primarily postthymic. DOCK8 mutant naive CD8 T cells had a shorter lifespan and, upon encounter with antigen on dendritic cells, exhibited poor LFA-1 synaptic polarization and a delay in the first cell division. Although DOCK8 mutant T cells underwent near-normal primary clonal expansion after primary infection with recombinant influenza virus in vivo, they showed greatly reduced memory cell persistence and recall. These findings highlight a key role for DOCK8 in the survival and function of human and mouse CD8 T cells.

scholarly journals Interleukin-7 Regulates Bim Proapoptotic Activity in Peripheral T-Cell Survival

2009 ◽  
Vol 30 (3) ◽  
pp. 590-600 ◽  
Author(s):  
Wen Qing Li ◽  
Tad Guszczynski ◽  
Julie A. Hixon ◽  
Scott K. Durum
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
T Cell Development ◽  
Cell Development ◽  
Effector Memory ◽  
Intracellular Location ◽  
Interleukin 7 ◽  
Peripheral T Cells ◽  
T Cell Survival

ABSTRACT Interleukin-7 (IL-7) is critical for T-cell development and peripheral T-cell homeostasis. The survival of pro-T cells and mature T cells requires IL-7. The survival function of IL-7 is accomplished partly through induction of the antiapoptotic protein Bcl-2 and inhibition of proapoptotic proteins Bax and Bad. We show here that the proapoptotic protein Bim, a BH3-only protein belonging to the Bcl-2 family, also plays a role in peripheral T-cell survival. Deletion of Bim partially protected an IL-7-dependent T-cell line and peripheral T cells, especially cells with an effector memory phenotype, from IL-7 deprivation. However, T-cell development in the thymus was not restored in IL-7−/− Rag2−/− mice reconstituted with Bim−/− bone marrow. IL-7 withdrawal altered neither the intracellular location of Bim, which was constitutively mitochondrial, nor its association with Bcl-2; however, a reduction in its association with the prosurvival protein Mcl-1 was observed. IL-7 withdrawal did not increase Bim mRNA or protein expression but did induce changes in the isoelectric point of BimEL and its reactivity with an antiphosphoserine antibody. Our findings suggest that the maintenance of peripheral T cells by IL-7 occurs partly through inhibition of Bim activity at the posttranslational level.

scholarly journals Self–class I MHC molecules support survival of naive CD8 T cells, but depress their functional sensitivity through regulation of CD8 expression levels

2009 ◽  
Vol 206 (10) ◽  
pp. 2253-2269 ◽  
Author(s):  
Kensuke Takada ◽  
Stephen C. Jameson
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Class I ◽  
Class I Mhc ◽  
Mhc Molecules ◽  
T Cell Survival ◽  
And Function

Previous studies have suggested that naive CD8 T cells require self-peptide–major histocompatability complex (MHC) complexes for maintenance. However, interpretation of such studies is complicated because of the involvement of lymphopenic animals, as lymphopenia drastically alters naive T cell homeostasis and function. In this study, we explored naive CD8 T cell survival and function in nonlymphopenic conditions by using bone marrow chimeric donors and hosts in which class I MHC expression is absent or limited to radiosensitive versus radioresistant cells. We found that long-term survival of naive CD8 T cells (but not CD4 T cells) was impaired in the absence of class I MHC. However, distinct from this effect, class I MHC deprivation also enhanced naive CD8 T cell responsiveness to low-affinity (but not high-affinity) peptide–MHC ligands. We found that this improved sensitivity was a consequence of up-regulated CD8 levels, which was mediated through a transcriptional mechanism. Hence, our data suggest that, in a nonlymphopenic setting, self-class I MHC molecules support CD8 T cell survival, but that these interactions also attenuate naive T cell sensitivity by dynamic tuning of CD8 levels.

scholarly journals TSC1/2 Signaling Complex Is Essential for Peripheral Naïve CD8+ T Cell Survival and Homeostasis in Mice

PLoS ONE ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. e30592 ◽  
Author(s):  
Lianjun Zhang ◽  
Hongbing Zhang ◽  
Lanlan Li ◽  
Yi Xiao ◽  
Enyu Rao ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Survival ◽  
Cd8 T Cell ◽  
Signaling Complex ◽  
T Cell Survival

scholarly journals Protein Kinase C-θ-Mediated Signals Enhance CD4+ T Cell Survival by Up-Regulating Bcl-xL

2006 ◽  
Vol 176 (11) ◽  
pp. 6709-6716 ◽  
Author(s):  
Santhakumar Manicassamy ◽  
Sonal Gupta ◽  
Zhaofeng Huang ◽  
Zuoming Sun
Keyword(s):  
Protein Kinase C ◽  
T Cell ◽  
Protein Kinase ◽  
Cell Survival ◽  
Cd4 T Cell ◽  
Kinase C ◽  
T Cell Survival
Sign in / Sign up

Export Citation Format

Share Document