Mustapha S, Kirshner A, De Moissac D, Kirshenbaum L A
Faculty of Medicine, Department of Physiology, Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6.
Am J Physiol Heart Circ Physiol. 2000 Sep;279(3):H939-45. doi: 10.1152/ajpheart.2000.279.3.H939.
Nuclear factor-kappa B (NF-kappa B) is a ubiquitously expressed cellular factor regulated by the cytoplasmic factor inhibitor protein kappa B alpha (I kappa B alpha). Activation of NF-kappa B by cytokines, including tumor necrosis factor-alpha (TNF-alpha), requires the phosphorylation and degradation of I kappa B alpha. An anti-apoptotic role for NF-kappa B has recently been suggested. In the present study, we ascertained whether death-promoting signals and apoptosis mediated by TNF-alpha are suppressed by NF-kappa B in postnatal ventricular myocytes. Stimulation of myocytes with TNF-alpha resulted in a 12.1-fold increase (P < 0.01) in NF-kappa B-dependent gene transcription and DNA binding compared with controls. This was accompanied by a corresponding increase in the NF-kappa B target protein A20 as determined by Western blot analysis. Vital staining revealed that TNF-alpha was not cytotoxic to myocytes and did not provoke apoptosis. Adenovirus-mediated delivery of a nonphosphorylatable form of I kappa B alpha to inactivate NF-kappa B prevented TNF-alpha-stimulated NF-kappa B-dependent gene transcription and nuclear NF-kappa B DNA binding. Importantly, myocytes stimulated with TNF-alpha and defective for NF-kappa B activation resulted in a 2.2-fold increase (P < 0.001) in apoptosis. To our knowledge, the data provide the first indication that a functional NF-kappa B signaling pathway is crucial for suppressing death-promoting signals mediated by TNF-alpha in ventricular myocytes.
核因子-κB（NF-κB）是一种广泛表达的细胞因子，受细胞质因子抑制剂κBα（IκBα）调控。包括肿瘤坏死因子-α（TNF-α）在内的细胞因子激活NF-κB需要IκBα的磷酸化和降解。最近有人提出NF-κB具有抗凋亡作用。在本研究中，我们确定了出生后心室肌细胞中NF-κB是否能抑制由TNF-α介导的促死亡信号和凋亡。与对照组相比，用TNF-α刺激心肌细胞导致NF-κB依赖的基因转录和DNA结合增加了12.1倍（P<0.01）。蛋白质免疫印迹分析显示，这伴随着NF-κB靶蛋白A20相应增加。活细胞染色显示，TNF-α对心肌细胞无细胞毒性，也不引发凋亡。腺病毒介导的不可磷酸化形式的IκBα的递送使NF-κB失活，阻止了TNF-α刺激的NF-κB依赖的基因转录和核NF-κB DNA结合。重要的是，用TNF-α刺激且NF-κB激活有缺陷的心肌细胞凋亡增加了2.2倍（P<0.001）。据我们所知，这些数据首次表明功能性NF-κB信号通路对于抑制心室肌细胞中由TNF-α介导的促死亡信号至关重要。
