TY - JOUR
T1 - Partial protection by poly(ADP-ribose) polymerase inhibitors from nitroxyl-induced cytotoxicity in thymocytes
AU - Bai, Péter
AU - Bakondi, Edina
AU - Szabó, Éva
AU - Gergely, Pál
AU - Szabó, Csaba
AU - Virág, László
N1 - Funding Information:
This work was supported by grants from the National Institutes of Health (R01GM60915), the Hungarian National Science Research Fund (OTKA T035182), and the Health Science Center of the University of Debrecen (Mec 10/99). L.V. was supported by a Bolyai fellowship from the Hungarian Academy of Sciences.
PY - 2001/12/15
Y1 - 2001/12/15
N2 - Nitroxyl (NO-/HNO), has been proposed to be one of the NO•-derived cytotoxic species. Although the biological effect of nitroxyl is largely unknown, it has been reported to cause DNA breakage and cytotoxicity. We have therefore investigated whether NO-/HNO-induced DNA single-strand breakage activates the nuclear nick sensor enzyme poly(ADP-ribose) polymerase (PARP) and whether PARP activation affects the mode of NO-/HNO- induced cell death. NO-/HNO generated from Angeli's salt (AS, sodium trioxodinitrate) (0-300 μM) induced DNA single-strand breakage, PARP activation, and a concentration-dependent cytotoxicity in murine thymocytes. AS-induced cell death was also accompanied by decreased mitochondrial membrane potential and increased secondary superoxide production. The cytotoxicity of AS, as measured by propidium iodide uptake, was abolished by electron acceptors potassium ferricyanide, TEMPOL, the intracellular calcium chelator BAPTA-AM, and by PARP inhibitors 3-aminobenzamide (3-AB) and PJ-34. The cytoprotective effect of 3-AB was paralleled by increased output of AS-induced apoptotic parameters such as phosphatidylserine exposure, caspase activation, and DNA fragmentation. No significant increase in tyrosine nitration could be observed in AS-treated thymocytes as opposed to peroxynitrite-treated cells, indicating that tyrosine nitration is not likely to contribute to NO-/HNO-induced cytotoxicity. Our results demonstrate that NO-/HNO-induced PARP activation shifts the default apoptotic cell death toward necrosis in thymocytes. However, as total PARP inhibition resulted only in 30% cytoprotection, PARP-independent mechanisms dominate NO-/HNO-induced cytotoxicity in thymocytes.
AB - Nitroxyl (NO-/HNO), has been proposed to be one of the NO•-derived cytotoxic species. Although the biological effect of nitroxyl is largely unknown, it has been reported to cause DNA breakage and cytotoxicity. We have therefore investigated whether NO-/HNO-induced DNA single-strand breakage activates the nuclear nick sensor enzyme poly(ADP-ribose) polymerase (PARP) and whether PARP activation affects the mode of NO-/HNO- induced cell death. NO-/HNO generated from Angeli's salt (AS, sodium trioxodinitrate) (0-300 μM) induced DNA single-strand breakage, PARP activation, and a concentration-dependent cytotoxicity in murine thymocytes. AS-induced cell death was also accompanied by decreased mitochondrial membrane potential and increased secondary superoxide production. The cytotoxicity of AS, as measured by propidium iodide uptake, was abolished by electron acceptors potassium ferricyanide, TEMPOL, the intracellular calcium chelator BAPTA-AM, and by PARP inhibitors 3-aminobenzamide (3-AB) and PJ-34. The cytoprotective effect of 3-AB was paralleled by increased output of AS-induced apoptotic parameters such as phosphatidylserine exposure, caspase activation, and DNA fragmentation. No significant increase in tyrosine nitration could be observed in AS-treated thymocytes as opposed to peroxynitrite-treated cells, indicating that tyrosine nitration is not likely to contribute to NO-/HNO-induced cytotoxicity. Our results demonstrate that NO-/HNO-induced PARP activation shifts the default apoptotic cell death toward necrosis in thymocytes. However, as total PARP inhibition resulted only in 30% cytoprotection, PARP-independent mechanisms dominate NO-/HNO-induced cytotoxicity in thymocytes.
KW - Apoptosis
KW - Free radicals
KW - Necrosis
KW - Nitric oxide
KW - Nitroxyl
KW - Poly(ADP-ribose) polymerase
UR - http://www.scopus.com/inward/record.url?scp=0035894091&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035894091&partnerID=8YFLogxK
U2 - 10.1016/S0891-5849(01)00756-0
DO - 10.1016/S0891-5849(01)00756-0
M3 - Article
C2 - 11744336
AN - SCOPUS:0035894091
SN - 0891-5849
VL - 31
SP - 1616
EP - 1623
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
IS - 12
ER -