The phosphatase inhibitor calyculin antagonizes the rapid initiation of apoptosis by photodynamic therapy.
DNA fragmentation and internucleosomal cleavage were rapidly initiated after lysosomal photodamage to murine leukemia cells, with apoptotic chromatin and DNA 'ladders' detected within 30 min after irradiation. Apoptosis was inhibited by concurrent exposure of cells to a 10 nM concentration of the serine-threonine phosphatase inhibitor calyculin A and promoted by a serine/threonine kinase inhibitor. These results indicate that a late stage in apoptosis requires serine/threonine dephosphorylation.
Luo
Y
Y
Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Kessel
D
D
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D047630:Depsipeptides; D004347:Drug Interactions; D008387:Marine Toxins; D051379:Mice; D008854:Microscopy, Electron; D010080:Oxazoles / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D010778:Photochemotherapy; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D014407:Tumor Cells, Cultured
D047630:Depsipeptides; D008387:Marine Toxins; D010080:Oxazoles; D010456:Peptides, Cyclic; C030051:didemnins; C059041:calyculin A; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases