Tyrosine kinase-dependent activation of a chloride channel in CD95-induced apoptosis in T lymphocytes.
CD95/Fas/APO-1 mediated apoptosis is an important mechanism in the regulation of the immune response. Here, we show that CD95 receptor triggering activates an outwardly rectifying chloride channel (ORCC) in Jurkat T lymphocytes. Ceramide, a lipid metabolite synthesized upon CD95 receptor triggering, also induces activation of ORCC in cell-attached patch clamp experiments. Activation is mediated by Src-like tyrosine kinases, because it is abolished by the tyrosine kinase inhibitor herbimycin A or by genetic deficiency of p56lck. In vitro incubation of excised patches with purified p56lck results in activation of ORCC, which is partially reversed upon addition of anti-phosphotyrosine antibody. Inhibition of ORCC by four different drugs correlates with a 30-65% inhibition of apoptosis. Intracellular acidification observed upon CD95 triggering is abolished by inhibition of either ORCC or p56lck. The results suggest that tyrosine kinase-mediated activation of ORCC may play a role in CD95-induced cell death in T lymphocytes.
Szabò
I
I
Department of Physiology, University of Tuebingen, Gmelinstrasse 5, 72076 Tuebingen, Germany.
Lepple-Wienhues
A
A
Kaba
K N
KN
Zoratti
M
M
Gulbins
E
E
Lang
F
F
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002518:Ceramides / Q000494:pharmacology; D018118:Chloride Channels / Q000502:physiology*; D053222:Fas Ligand Protein; D006801:Humans; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology*; D019014:fas Receptor / Q000502:physiology*
D002518:Ceramides; D018118:Chloride Channels; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019014:fas Receptor; D011505:Protein-Tyrosine Kinases