The tyrosine kinase Lck is involved in regulation of mitochondrial apoptosis pathways.
The induction of apoptosis requires the activation of a highly coordinated signaling network ultimately leading to the activation of caspases. In previous experiments we and others have shown that the tyrosine kinase Lck is required for adequate apoptosis induction in response to ionizing radiation, ceramide incubation and overexpression of the HIV-TAT protein. However, the position of Lck within given apoptotic signaling cascades remains unclear. We therefore aimed to define the role of Lck during radiation-induced apoptosis. Apoptosis induction in response to ionizing radiation, CD95 or TRAIL receptor stimulation was determined in Jurkat T-cells, the Lck-deficient Jurkat clone JCaM1.6- and Lck-retransfected JCaM1.6/Lck. No apoptosis, release of cytochrome c, breakdown of the mitochondrial potential were detectable during the first 48 h after irradiation of JCaM1.6 cells. In parallel, no activation of caspase-9, -8 and -3 was detectable. Since mitochondrial apoptosis pathways act within a feedback mechanism during death-receptor-mediated apoptosis, the influence of the Lck defect on CD95/Fas/Apo-1-L or TRAIL-induced apoptosis was also tested. Both stimuli induced apoptosis in Lck-deficient cells. However, the kinetics of apoptosis induction determined by caspase-8, -9 and -3 activation as well as deltapsi(m) breakdown was slowed. We conclude that the Lck deficiency influences early steps during radiation-induced mitochondrial alterations.
Belka
Claus
C
Department of Radiation Oncology, University of Tübingen, Germany. claus.belka@uni-tuebingen.de
Gruber
Charlotte
C
Jendrossek
Verena
V
Wesselborg
Sebastian
S
Budach
Wilfried
W
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D051017:Apoptosis Regulatory Proteins; D017252:CD3 Complex / Q000187:drug effects / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000528:radiation effects; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008564:Membrane Potentials / Q000528:radiation effects; D008928:Mitochondria / Q000378:metabolism* / Q000528:radiation effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010835:Phytohemagglutinins / Q000494:pharmacology; D010940:Plant Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism / Q000528:radiation effects; D011839:Radiation, Ionizing; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D017252:CD3 Complex; D003574:Cytochrome c Group; D008562:Membrane Glycoproteins; D010835:Phytohemagglutinins; D010940:Plant Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C101135:phytohemagglutinin L protein, Phaseolus vulgaris; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases