Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x.
Modulation of cytokine-induced cardiac myocyte apoptosis by nitric oxide, Bak, and Bcl-x.
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DOI：
10.1161/01.res.84.1.21
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发表时间：
1999-01
影响因子：
20.1
通讯作者：
Douglas J. Ing;Jie Zang;Victor J. Dzau;Keith A. Webster;N. Bishopric
中科院分区：
文献类型：
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作者：
Douglas J. Ing;Jie Zang;Victor J. Dzau;Keith A. Webster;N. Bishopric
-细胞因子诱导的NO产生抑制心肌收缩能力，并已被证明对心肌细胞具有细胞毒性。然而，细胞因子诱导心肌细胞死亡的机制尚不清楚。为了详细分析这些机制，我们在无血清培养中用巨噬细胞衍生细胞因子IL-1β、肿瘤坏死因子-α和干扰素-γ的组合处理新生心肌细胞。从治疗72小时后开始，这些细胞因子引起心肌细胞的时间依赖性的诱导凋亡，但不是坏死，通过核形态、DNA核小体间裂解和多聚(ADP-核糖)聚合酶的裂解来确定，反映caspase的激活。在细胞凋亡之前，可诱导50倍的诱导型一氧化氮合酶基因的表达和大量(5~8nmol/微克蛋白)的一氧化氮代谢产物(NOx)进入培养基内。细胞死亡被一氧化氮合酶抑制剂完全阻断，并被抗氧化剂(N-乙酰半胱氨酸和DTT)和半胱氨酸氨基转移酶抑制剂zVAD-fmk减弱。细胞因子还介导了心肌细胞Bcl2同源物Bak和Bclx的NO依赖的持续增加(L)。NO供体S-亚硝基-谷胱甘肽也能诱导细胞凋亡和Bak的表达，但不能诱导Bclx的表达(L)。包括多聚ADP-核糖聚合酶裂解在内的所有细胞因子的作用都可归因于IL-1β；干扰素-γ和肿瘤坏死因子-α对细胞凋亡或NOx的产生没有独立的作用。我们得出结论，细胞因子对新生儿心肌细胞的毒性是由于NO的诱导和随后的细胞凋亡的激活，至少部分是通过氧自由基的产生。细胞凋亡的速度和程度受到Bak和Bclx(L)细胞平衡的改变的调节，Bak和Bclx对细胞因子诱导和外源性NO的反应不同，氧化剂物种的可获得性也不同。
-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-1beta, tumor necrosis factor-alpha, and interferon-gamma. 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/ microgram 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-1beta; interferon-gamma and tumor necrosis factor-alpha 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.