PI3K/Akt signaling pathway involved in regulation of T lymphocyte activation and apoptosis mediated by CD3ε

To study the expression and kinase activity of phosphatidylinositol 3′ -kinase (PI3K) and protein kinase B (PKB or Akt) during activation and apoptosis of human Jurkat T lymphocytes (TJK) with stable expression of CD8ε chimera fused human CD8α extracellular and transmembrane domains to intracellular domain of mouse CD3ε, Western blot, kinase activities detection and immunoprecipitation were carried out. It was shown that Jurkat cells with expression of wild type chimera CD8ε died by apoptosis after continuous stimulation of anti-CD8 monoclonal antibody. The expressions of PI3K and Akt, and the kinase activity of Akt remarkably increased during the process. However, this phenomenon did not occur in the Jurkat cells (T1JK) with expression of the mutant of CD8ε chimera (Y170F), suggesting that PI3K/Akt signaling pathway is involved in activation and apoptosis of T lymphocyte mediated by CD3ε.