Jun C D, Pae H O, Kwak H J, Yoo J C, Choi B M, Oh C D, Chun J S, Paik S G, Park Y H, Chung H T
Department of Microbiology and Immunology, Wonkwang University School of Medicine and Medicinal Resources Research Center of Wonkwang University, Chonbuk, Iksan.
Cell Immunol. 1999 May 25;194(1):36-46. doi: 10.1006/cimm.1999.1480.
To define the signaling pathways during NO-induced apoptotic events and their possible modulation by two protein kinase systems, we explored the involvement of three structurally related mitogen-activated protein kinase subfamilies. Exposure of HL-60 cells to sodium nitroprusside (SNP) strongly activated p38 kinase, but did not activate c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). In addition, SNP-induced apoptosis was markedly blocked by the selective p38 kinase inhibitor (SB203580) but not by MEK1 kinase inhibitor (PD098059), indicating that p38 kinase serves as a mediator of NO-induced apoptosis. In contrast, treatment of cells with phorbol 12-myristate 13-acetate (PMA) strongly activated not only JNK but also ERK, while not affecting p38 kinase. However, although SNP by itself weakly activated CPP32-like protease, SNP in combination with PMA markedly increased the extent of CPP32-like protease activation. Interestingly, N6,O2-dibutylyl cAMP (DB-cAMP) significantly blocked SNP- or SNP plus PMA-induced activation of CPP32-like protease and the resulting induction of apoptosis. DB-cAMP also blocked PMA-induced JNK activation. Collectively, these findings demonstrate the presence of specific up- or down-modulatory mechanisms of cell death pathway by NO in which (1) p38 kinase serves as a mediator of NO-induced apoptosis, (2) PKC acts at the point and/or upstream of JNK and provides signals to potentiate NO-induced CPP32-like protease activation, and (3) PKA lies upstream of either JNK or CPP32-like protease to protect NO- or NO plus PMA-induced apoptotic cell death in HL-60 cells.
为了确定一氧化氮（NO）诱导凋亡过程中的信号通路以及两个蛋白激酶系统对其可能的调节作用，我们研究了三个结构相关的丝裂原活化蛋白激酶亚家族的参与情况。将HL-60细胞暴露于硝普钠（SNP）可强烈激活p38激酶，但不激活c-Jun氨基末端激酶（JNK）和细胞外信号调节激酶（ERK）。此外，SNP诱导的凋亡被选择性p38激酶抑制剂（SB203580）显著阻断，但未被MEK1激酶抑制剂（PD098059）阻断，这表明p38激酶是NO诱导凋亡的介导因子。相反，用佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA）处理细胞不仅强烈激活JNK，还激活ERK，而不影响p38激酶。然而，尽管SNP本身可微弱激活CPP32样蛋白酶，但SNP与PMA联合使用可显著增加CPP32样蛋白酶的激活程度。有趣的是，N6,O2-二丁酰环磷腺苷（DB-cAMP）可显著阻断SNP或SNP加PMA诱导的CPP32样蛋白酶激活以及由此导致的凋亡诱导。DB-cAMP还可阻断PMA诱导的JNK激活。总体而言，这些发现表明NO存在细胞死亡途径的特定上调或下调调节机制，其中（1）p38激酶是NO诱导凋亡的介导因子，（2）蛋白激酶C（PKC）作用于JNK的作用点和/或上游，并提供信号增强NO诱导的CPP32样蛋白酶激活，（3）蛋白激酶A（PKA）位于JNK或CPP32样蛋白酶的上游，以保护HL-60细胞免受NO或NO加PMA诱导的凋亡性细胞死亡。
