Dynamics of proximal signaling events after TCR/CD8-mediated induction of proliferation or apoptosis in mature CD8+ T cells

J Immunol. 2008 May 15;180(10):6703-12. doi: 10.4049/jimmunol.180.10.6703.

Abstract

Engagement of the TCR can induce different functional outcomes such as activation, proliferation, survival, or apoptosis. How the TCR-mediated signaling cascades generating these distinct cellular responses are organized on the molecular level is so far not completely understood. To obtain insight into this question, we analyzed TCR/CD8-mediated signaling events in mature OT-I TCR transgenic T cells under conditions of stimulation that lead to either proliferation or apoptosis. These experiments revealed major differences in the phosphorylation dynamics of LAT, ZAP70, protein kinase B, phospholipase C-gamma1, protein kinase D1, and ERK1/2. Moreover, input signals leading to apoptosis induced a strong, but transient activation of ERK1/2 mainly at sites of TCR-engagement. In contrast, stimuli promoting survival/proliferation generated a low and sustained activation of ERK1/2, which colocalizes with Ras in recycling endosomal vesicles. The transient activation of ERK1/2 under pro-apoptotic conditions of stimulation is at least partially due to the rapid polyubiquitination and subsequent degradation of ZAP70, whereas the sustained activation of ERK1/2 under survival promoting conditions is paralleled by the induction/phosphorylation of anti-apoptotic molecules such as protein kinase B and Bcl-x(L). Collectively, our data provide signaling signatures that are associated with proliferation or apoptosis of T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / immunology*
  • Blotting, Western
  • CD8 Antigens / immunology
  • CD8 Antigens / metabolism*
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • Cell Proliferation
  • Enzyme Activation / immunology
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Flow Cytometry
  • Gene Expression / immunology
  • Gene Expression Regulation / immunology
  • Humans
  • Immunoprecipitation
  • Lymphocyte Activation / immunology*
  • Mice
  • Mice, Transgenic
  • Microscopy, Confocal
  • Phosphorylation
  • Receptors, Antigen, T-Cell / genetics
  • Receptors, Antigen, T-Cell / immunology
  • Receptors, Antigen, T-Cell / metabolism*
  • Signal Transduction / immunology*
  • Ubiquitination
  • ZAP-70 Protein-Tyrosine Kinase / metabolism

Substances

  • CD8 Antigens
  • Receptors, Antigen, T-Cell
  • ZAP-70 Protein-Tyrosine Kinase
  • Extracellular Signal-Regulated MAP Kinases