title: Tyrosine kinase-dependent activation of a chloride channel in CD95-induced apoptosis in T lymphocytes.
abstract: 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.
authors.affiliation: Department of Physiology, University of Tuebingen, Gmelinstrasse 5, 72076 Tuebingen, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Szabò
authors.forename: A
authors.initials: A
authors.lastname: Lepple-Wienhues
authors.forename: K N
authors.initials: KN
authors.lastname: Kaba
authors.forename: M
authors.initials: M
authors.lastname: Zoratti
authors.forename: E
authors.initials: E
authors.lastname: Gulbins
authors.forename: F
authors.initials: F
authors.lastname: Lang
mesh_terms: 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*
chemical_list: D002518:Ceramides; D018118:Chloride Channels; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019014:fas Receptor; D011505:Protein-Tyrosine Kinases