Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x

Douglas J. Ing, Jie Zang, Victor J. Dzau, Keith A Webster, Nanette Bishopric

Research output: Contribution to journalArticle

221 Citations (Scopus)

Abstract

Cytokine-induced NO production depresses myocardial contractility and has been shown to be cytotoxic to cardiac myocytes. However, the mechanisms of cytokine-induced cardiac myocyte cell death are unclear. To analyze these mechanisms in detail, we treated neonatal cardiac myocytes in serum-free culture with a combination of the macrophage-derived cytokines interleukin- 1β, tumor necrosis factor-α, and interferon-γ. These cytokines caused a time-dependent induction of cardiac myocyte apoptosis, but not necrosis, beginning 72 hours after treatment, as determined by nuclear morphology, DNA internucleosomal cleavage, and cleavage of poly(ADP-ribose) polymerase, reflecting caspase activation. Apoptosis was preceded by a >50-fold induction of inducible NO synthase mRNA and the release of large amounts (5 to 8 nmol/μg protein) of NO metabolites (NOx) into the medium. Cell death was completely blocked by an NO synthase inhibitor and attenuated by antioxidants (N-acetylcysteine and DTT) and the caspase inhibitor ZVAD-fmk. Cytokines also mediated an NO-dependent, sustained increase in myocyte expression of the Bcl-2 homologs Bak and Bcl-x(L). The NO donor S-nitrosoglutathione also induced apoptosis and cell levels of Bak, but not of Bcl-x(L). All effects of cytokines, including poly(ADP-ribose) polymerase cleavage, could be attributed to interleukin-1β; interferon-γ and tumor necrosis factor-α had no independent effects on apoptosis or on NOx production. We conclude that cytokine toxicity to neonatal cardiac myocytes results from the induction of NO and subsequent activation of apoptosis, at least in part through the generation of oxygen free radicals. The rate and extent of this apoptosis is modulated by alterations in the cellular balance of Bak and Bcl-x(L), which respond differentially to cytokine-induced and exogenous NO and by the availability of oxidant species.

Original languageEnglish
Pages (from-to)21-33
Number of pages13
JournalCirculation Research
Volume84
Issue number1
StatePublished - Jan 8 1999

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Cardiac Myocytes
Nitric Oxide
Apoptosis
Cytokines
Poly(ADP-ribose) Polymerases
Interleukin-1
Nitric Oxide Synthase
Interferons
Cell Death
Tumor Necrosis Factor-alpha
S-Nitrosoglutathione
DNA Cleavage
Caspase Inhibitors
Acetylcysteine
Caspases
Oxidants
Muscle Cells
Free Radicals
Reactive Oxygen Species
Necrosis

Keywords

  • Bcl- x(L)
  • Nitric oxide
  • Oxidative stress
  • Poly(ADP-ribose) polymerase
  • Protein kinase G

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Ing, D. J., Zang, J., Dzau, V. J., Webster, K. A., & Bishopric, N. (1999). Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x. Circulation Research, 84(1), 21-33.

Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x. / Ing, Douglas J.; Zang, Jie; Dzau, Victor J.; Webster, Keith A; Bishopric, Nanette.

In: Circulation Research, Vol. 84, No. 1, 08.01.1999, p. 21-33.

Research output: Contribution to journalArticle

Ing, DJ, Zang, J, Dzau, VJ, Webster, KA & Bishopric, N 1999, 'Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x', Circulation Research, vol. 84, no. 1, pp. 21-33.
Ing DJ, Zang J, Dzau VJ, Webster KA, Bishopric N. Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x. Circulation Research. 1999 Jan 8;84(1):21-33.
Ing, Douglas J. ; Zang, Jie ; Dzau, Victor J. ; Webster, Keith A ; Bishopric, Nanette. / Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x. In: Circulation Research. 1999 ; Vol. 84, No. 1. pp. 21-33.
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N2 - Cytokine-induced NO production depresses myocardial contractility and has been shown to be cytotoxic to cardiac myocytes. However, the mechanisms of cytokine-induced cardiac myocyte cell death are unclear. To analyze these mechanisms in detail, we treated neonatal cardiac myocytes in serum-free culture with a combination of the macrophage-derived cytokines interleukin- 1β, tumor necrosis factor-α, and interferon-γ. These cytokines caused a time-dependent induction of cardiac myocyte apoptosis, but not necrosis, beginning 72 hours after treatment, as determined by nuclear morphology, DNA internucleosomal cleavage, and cleavage of poly(ADP-ribose) polymerase, reflecting caspase activation. Apoptosis was preceded by a >50-fold induction of inducible NO synthase mRNA and the release of large amounts (5 to 8 nmol/μg protein) of NO metabolites (NOx) into the medium. Cell death was completely blocked by an NO synthase inhibitor and attenuated by antioxidants (N-acetylcysteine and DTT) and the caspase inhibitor ZVAD-fmk. Cytokines also mediated an NO-dependent, sustained increase in myocyte expression of the Bcl-2 homologs Bak and Bcl-x(L). The NO donor S-nitrosoglutathione also induced apoptosis and cell levels of Bak, but not of Bcl-x(L). All effects of cytokines, including poly(ADP-ribose) polymerase cleavage, could be attributed to interleukin-1β; interferon-γ and tumor necrosis factor-α had no independent effects on apoptosis or on NOx production. We conclude that cytokine toxicity to neonatal cardiac myocytes results from the induction of NO and subsequent activation of apoptosis, at least in part through the generation of oxygen free radicals. The rate and extent of this apoptosis is modulated by alterations in the cellular balance of Bak and Bcl-x(L), which respond differentially to cytokine-induced and exogenous NO and by the availability of oxidant species.

AB - Cytokine-induced NO production depresses myocardial contractility and has been shown to be cytotoxic to cardiac myocytes. However, the mechanisms of cytokine-induced cardiac myocyte cell death are unclear. To analyze these mechanisms in detail, we treated neonatal cardiac myocytes in serum-free culture with a combination of the macrophage-derived cytokines interleukin- 1β, tumor necrosis factor-α, and interferon-γ. These cytokines caused a time-dependent induction of cardiac myocyte apoptosis, but not necrosis, beginning 72 hours after treatment, as determined by nuclear morphology, DNA internucleosomal cleavage, and cleavage of poly(ADP-ribose) polymerase, reflecting caspase activation. Apoptosis was preceded by a >50-fold induction of inducible NO synthase mRNA and the release of large amounts (5 to 8 nmol/μg protein) of NO metabolites (NOx) into the medium. Cell death was completely blocked by an NO synthase inhibitor and attenuated by antioxidants (N-acetylcysteine and DTT) and the caspase inhibitor ZVAD-fmk. Cytokines also mediated an NO-dependent, sustained increase in myocyte expression of the Bcl-2 homologs Bak and Bcl-x(L). The NO donor S-nitrosoglutathione also induced apoptosis and cell levels of Bak, but not of Bcl-x(L). All effects of cytokines, including poly(ADP-ribose) polymerase cleavage, could be attributed to interleukin-1β; interferon-γ and tumor necrosis factor-α had no independent effects on apoptosis or on NOx production. We conclude that cytokine toxicity to neonatal cardiac myocytes results from the induction of NO and subsequent activation of apoptosis, at least in part through the generation of oxygen free radicals. The rate and extent of this apoptosis is modulated by alterations in the cellular balance of Bak and Bcl-x(L), which respond differentially to cytokine-induced and exogenous NO and by the availability of oxidant species.

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