NGF withdrawal induces apoptosis in CESS B cell line through p38 MAPK activation and Bcl-2 phosphorylation.
The sIgG(+) lymphoblastoid B cell line CESS spontaneously produces a high amount of NGF and expresses both high affinity (p140(Trk-A)) and low affinity (p75(NTR)) NGF receptors. Blocking NGF signals with neutralizing antibodies or specific Trk-A inhibitors induces a rapid phosphorylation of antiapoptotic Bcl-2 protein, followed by caspase activation, and apoptotic death of CESS cells. Bcl-2 phosphorylation in several sites within a approximately 60 aa "loop" domain of protein is known to regulate its antiapoptotic function. Accordingly, CESS cells expressing the loop deletional mutant cDNA constructs Bcl-2 Delta40-91 were completely resistant to apoptosis induced by NGF withdrawal, indicating that Bcl-2 phosphorylation is a critical event. NGF withdrawal induces p38 MAPK, but not JNK, activation in CESS cells, and SB203580, a specific inhibitor of p38 MAPK, is able to prevent both Bcl-2 phosphorylation and apoptosis, indicating that p38 MAPK is the enzyme responsible for these events.
Rosini
P
P
Department of Clinical Physiopathology, University of Florence, Florence, Italy.
De Chiara
G
G
Lucibello
M
M
Garaci
E
E
Cozzolino
F
F
Torcia
M
M
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001402:B-Lymphocytes; D002227:Carbazoles / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019254:Genes, bcl-2; D006801:Humans; D026121:Indole Alkaloids; D048031:JNK Mitogen-Activated Protein Kinases; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000494:pharmacology*; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D020917:Receptor, trkA / Q000235:genetics / Q000502:physiology; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000502:physiology; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured; D020032:Tyrphostins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
C081020:AG-879; D002227:Carbazoles; D004791:Enzyme Inhibitors; D026121:Indole Alkaloids; D019253:Proto-Oncogene Proteins c-bcl-2; D017475:Receptors, Nerve Growth Factor; D020032:Tyrphostins; D020932:Nerve Growth Factor; C049985:staurosporine aglycone; D020917:Receptor, trkA; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases