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Peroxynitrite-induced thymocyte apoptosis: the role of caspases and poly (ADP-ribose) synthetase (PARS) activation.
Immunology. 1998 Jul; 94(3):345-55.I

Abstract

The mechanisms by which immature thymocyte apoptosis is induced during negative selection are poorly defined. Reports demonstrated that cross-linking of T-cell receptor leads to stromal cell activation, expression of inducible nitric oxide synthase (iNOS) and, subsequently, to thymocyte apoptosis. Therefore we examined, whether NO directly or indirectly, through peroxynitrite formation, causes thymocyte apoptosis. Immuno-histochemical detection of nitrotyrosine revealed in vivo peroxynitrite formation in the thymi of naive mice. Nitrotyrosine, the footprint of peroxynitrite, was predominantly found in the corticomedullary junction and the medulla of naive mice. In the thymi of mice deficient in the inducible isoform of nitric oxide synthase, considerably less nitrotyrosine was found. Exposure of thymocytes in vitro to low concentrations (10 microM) of peroxynitrite led to apoptosis, whereas higher concentrations (50 microM) resulted in intense cell death with the characteristics of necrosis. We also investigated the effect of poly (ADP-ribose) synthetase (PARS) inhibition on thymocyte apoptosis. Using the PARS inhibitor 3-aminobenzamide (3-AB), or thymocytes from PARS-deficient animals, we established that PARS determines the fate of thymocyte death. Suppression of cellular ATP levels, and the cellular necrosis in response to peroxynitrite were prevented by PARS inhibition. Therefore, in the absence of PARS, cells are diverted towards the pathway of apoptotic cell death. Similar results were obtained with H2O2 treatment, while apoptosis induced by non-oxidative stimuli such as dexamethasone or anti-FAS antibody was unaffected by PARS inhibition. In conclusion, we propose that peroxynitrite-induced apoptosis may play a role in the process of thymocyte negative selection. Furthermore, we propose that the physiological role of PARS cleavage by apopain during apoptosis may serve as an energy-conserving step, enabling the cell to complete the process of apoptosis.

Authors+Show Affiliations

Division of Critical Care, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9767416

Citation

Virág, L, et al. "Peroxynitrite-induced Thymocyte Apoptosis: the Role of Caspases and Poly (ADP-ribose) Synthetase (PARS) Activation." Immunology, vol. 94, no. 3, 1998, pp. 345-55.
Virág L, Scott GS, Cuzzocrea S, et al. Peroxynitrite-induced thymocyte apoptosis: the role of caspases and poly (ADP-ribose) synthetase (PARS) activation. Immunology. 1998;94(3):345-55.
Virág, L., Scott, G. S., Cuzzocrea, S., Marmer, D., Salzman, A. L., & Szabó, C. (1998). Peroxynitrite-induced thymocyte apoptosis: the role of caspases and poly (ADP-ribose) synthetase (PARS) activation. Immunology, 94(3), 345-55.
Virág L, et al. Peroxynitrite-induced Thymocyte Apoptosis: the Role of Caspases and Poly (ADP-ribose) Synthetase (PARS) Activation. Immunology. 1998;94(3):345-55. PubMed PMID: 9767416.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Peroxynitrite-induced thymocyte apoptosis: the role of caspases and poly (ADP-ribose) synthetase (PARS) activation. AU - Virág,L, AU - Scott,G S, AU - Cuzzocrea,S, AU - Marmer,D, AU - Salzman,A L, AU - Szabó,C, PY - 1998/10/10/pubmed PY - 1998/10/10/medline PY - 1998/10/10/entrez SP - 345 EP - 55 JF - Immunology JO - Immunology VL - 94 IS - 3 N2 - The mechanisms by which immature thymocyte apoptosis is induced during negative selection are poorly defined. Reports demonstrated that cross-linking of T-cell receptor leads to stromal cell activation, expression of inducible nitric oxide synthase (iNOS) and, subsequently, to thymocyte apoptosis. Therefore we examined, whether NO directly or indirectly, through peroxynitrite formation, causes thymocyte apoptosis. Immuno-histochemical detection of nitrotyrosine revealed in vivo peroxynitrite formation in the thymi of naive mice. Nitrotyrosine, the footprint of peroxynitrite, was predominantly found in the corticomedullary junction and the medulla of naive mice. In the thymi of mice deficient in the inducible isoform of nitric oxide synthase, considerably less nitrotyrosine was found. Exposure of thymocytes in vitro to low concentrations (10 microM) of peroxynitrite led to apoptosis, whereas higher concentrations (50 microM) resulted in intense cell death with the characteristics of necrosis. We also investigated the effect of poly (ADP-ribose) synthetase (PARS) inhibition on thymocyte apoptosis. Using the PARS inhibitor 3-aminobenzamide (3-AB), or thymocytes from PARS-deficient animals, we established that PARS determines the fate of thymocyte death. Suppression of cellular ATP levels, and the cellular necrosis in response to peroxynitrite were prevented by PARS inhibition. Therefore, in the absence of PARS, cells are diverted towards the pathway of apoptotic cell death. Similar results were obtained with H2O2 treatment, while apoptosis induced by non-oxidative stimuli such as dexamethasone or anti-FAS antibody was unaffected by PARS inhibition. In conclusion, we propose that peroxynitrite-induced apoptosis may play a role in the process of thymocyte negative selection. Furthermore, we propose that the physiological role of PARS cleavage by apopain during apoptosis may serve as an energy-conserving step, enabling the cell to complete the process of apoptosis. SN - 0019-2805 UR - https://www.unboundmedicine.com/medline/citation/9767416/Peroxynitrite_induced_thymocyte_apoptosis:_the_role_of_caspases_and_poly__ADP_ribose__synthetase__PARS__activation_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0019-2805&date=1998&volume=94&issue=3&spage=345 DB - PRIME DP - Unbound Medicine ER -