Protein tyrosine kinases and phosphatases control apoptosis induced by extracellular adenosine 5'-triphosphate.
Extracellular ATP (ATPo) induces apoptosis and osmotic lysis in several cell lines. We investigated the role of protein tyrosine kinases (PTKs) and phosphatases (PTPases) in ATPo-induced apoptosis. The PTK inhibitor genistein prevented DNA fragmentation due to ATPo without affecting cell lysis. Comparison of western blot analysis and in vitro kinase assays of anti-phosphotyrosine immunoprecipitates indicated that ATPo activated PTKs whose activity was tightly regulated by PTPases. In fact, an early increase in tyrosine kinase activity was observed after ATPo-treatment and was prevented by specific PTPase inhibitors. In addition, a rapid dephosphorylation of phosphotyrosyl residues on several proteins was detected in ATPo-treated cells. Accordingly, inhibitors of PTPases, but not of serine/threonine phosphatases, were as effective as PTK-inhibitors in blocking ATPo-mediated DNA fragmentation. We describe the early events occurring in ATPo-induced apoptosis and suggest a role for PTPases in cell death.
Bronte
V
V
Institute of Oncology, Inter-University Center for Cancer Research, Padova, Italy.
Macino
B
B
Zambon
A
A
Rosato
A
A
Mandruzzato
S
S
Zanovello
P
P
Collavo
D
D
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002460:Cell Line; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein; D006706:Homeostasis; D007529:Isoflavones / Q000494:pharmacology; D007939:Leukemia L1210; D012515:Mast-Cell Sarcoma; D051379:Mice; D019000:Phosphotyrosine / Q000032:analysis; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014638:Vanadates / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007529:Isoflavones; D019000:Phosphotyrosine; D014638:Vanadates; D000255:Adenosine Triphosphate; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases