Calcium-induced ERK activation in human T lymphocytes

We have previously shown that stimulation of B lymphocytes with calcium ion ophores lead to the phosphorylation and enzymatic activation of ERK2. We ha ve now determined that stimulation of human primary and Jurkat T lymphocyte s with ionomycin also results in the activation of ERK1 and 2 as determined by; shifts in the mobility of this enzyme on SDS-PACE gels, the binding of an antibody that recognizes only the activated form of this enzyme, and in creased ability to phosphorylate myelin basic protein (MBP). Another calciu m ionophore, A23187, also induced activation of ERK1 and 2 in human primary and Jurkat T lymphocytes demonstrating that this is a general effect of ca lcium ionophores and is not limited to ionomycin. The activation of ERK1 an d 2 by calcium ionophores was rapid, transient, and occurred in a dose-depe ndent manner. Activation of ERK1 and 2 by increases in intracellular calciu m were blocked by the MEK inhibitor PD98059. These data point to a new role for calcium fluxes in T lymphocytes. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.