PI3K/Akt signaling pathway involved in regulation of T lymphocyte activation and apoptosis mediated by CD3 epsilon

To study the expression and kinase activity of phosphatidylinositol 3 ' -ki nase (PI3K) and protein kinase B (PKB or Akt) during activation and apoptos is of human Jurkat T lymphocytes (TJK) with stable expression of CD8 epsilo n chimera fused human CD8 alpha extracellular and transmembrane domains to intracellular domain of mouse CD3 epsilon, Western blot, kinase activities detection and immunoprecipitation were carried out. It was shown that Jurka t cells with expression of wild type chimera CD8 epsilon died by apoptosis after continuous stimulation of anti-CD8 monoclonal antibody. The expressio ns of PI3K and Akt, and the kinase activity of Akt remarkably increased dur ing the process, However, this phenomenon did not occur in the Jurkat cells (T1JK) with expression of the mutant of CD8 epsilon chimera (Y170F), sugge sting that PI3K/Akt signaling pathway is involved in activation and apoptos is of T lymphocyte mediated by CD3 epsilon.