title: Mechanism of UV-induced apoptosis in human leukemia cells: roles of Ca2+/Mg(2+)-dependent endonuclease, caspase-3, and stress-activated protein kinases.
abstract: Ultraviolet light (UV) induced rapid apoptosis of U937 leukemia cells, concurrent with DNA fragmentation and cleavage of poly(ADP-ribose)polymerase (PARP) by activated caspase-3. The in vitro reconstitution of intact HeLa S3 nuclei and apoptotic U937 cytosolic extract (CE) revealed that (i) Ca2+/Mg(2+)-dependent, Zn(2+)-sensitive endonuclease activated in the apoptotic CE induced DNA ladder in HeLa nuclei at pH 6.8-7.4, (ii) activated caspase-3 cleaved PARP in HeLa nuclei, and (iii) when the apoptotic CE was treated with the caspase-3 inhibitor (1 microM Ac-DEVD-CHO) or the caspase-1 inhibitor (10 microM Ac-YVAD-CHO), the former, but not the latter, caused a 50% inhibition of DNA fragmentation and the complete inhibition of PARP cleavage in HeLa nuclei. Similarly, Ac-DEVD-CHO (100 microM) inhibited apoptosis and DNA ladder by 50% and PARP cleavage completely in UV-irradiated U937 cells, but Ac-YVAD-CHO (100 microM) did not. Thus, UV-induced apoptosis of U937 cells involves the Ca2+/Mg(2+)-dependent endonuclease pathway and the caspase-3-PARP cleavage-Ca2+/Mg(2+)-dependent endonuclease pathway. The former pathway produced directly 50% of apoptotic DNA ladder, and the latter involved activated caspase-3 and PARP cleavage, followed by formation of the remaining 50% DNA ladder by the activated endonuclease. In UV-irradiated B-cell lines, further, p53-dependent increase of Bax resulted in a greater caspase-3 activation compared to its absence. However, UV-induced activation of JNK1 and p38 was not affected by the caspase-1 and -3 inhibitors in U937 cells, so that caspases-1 and -3 do not function upstream of JNK1 and p38.
authors.affiliation: Department of Radiation Biophysics and Genetics, Kobe University School of Medicine, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Kimura
authors.forename: Q L
authors.initials: QL
authors.lastname: Zhao
authors.forename: T
authors.initials: T
authors.lastname: Kondo
authors.forename: M
authors.initials: M
authors.lastname: Amatsu
authors.forename: Y
authors.initials: Y
authors.lastname: Fujiwara
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D001402:B-Lymphocytes / Q000201:enzymology / Q000528:radiation effects; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D020170:Caspase 1; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000502:physiology*; D004789:Enzyme Activation / Q000528:radiation effects; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D016403:Lymphoma, Large B-Cell, Diffuse / Q000201:enzymology / Q000473:pathology*; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D014466:Ultraviolet Rays; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C494826:BAX protein, human; D015853:Cysteine Proteinase Inhibitors; D004273:DNA, Neoplasm; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; D051028:bcl-2-Associated X Protein; C096429:L 709049; D011065:Poly(ADP-ribose) Polymerases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D004706:Endodeoxyribonucleases; C029367:calcium magnesium dependent endodeoxyribonuclease; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D020170:Caspase 1