Chen Ku-Chung, Kao Pei-Hsiu, Lin Shinne-Ren, Chang Long-Sen
Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
J Cell Biochem. 2009 Jan 1;106(1):93-102. doi: 10.1002/jcb.21979.
The aim of the present study is to elucidate the signaling pathway involved in death of human neuroblastoma SK-N-SH cells induced by Naja naja atra phospholipase A(2) (PLA(2)). Upon exposure to PLA(2), p38 MAPK activation, ERK inactivation, ROS generation, increase in intracellular Ca(2+) concentration, and upregulation of Fas and FasL were found in SK-N-SH cells. SB202190 (p38MAPK inhibitor) suppressed upregulation of Fas and FasL. N-Acetylcysteine (ROS scavenger) and BAPTA-AM (Ca(2+) chelator) abrogated p38 MAPK activation and upregulation of Fas and FasL expression, but restored phosphorylation of ERK. Activated ERK was found to attenuate p38 MAPK-mediated upregulation of Fas and FasL. Deprivation of catalytic activity could not diminish PLA(2)-induced cell death and Fas/FasL upregulation. Moreover, the cytotoxicity of arachidonic acid and lysophosphatidylcholine was not related to the expression of Fas and FasL. Taken together, our results indicate that PLA(2)-induced cell death is, in part, elicited by upregulation of Fas and FasL, which is regulated by Ca(2+)- and ROS-evoked p38 MAPK activation, and suggest that non-catalytic PLA(2) plays a role for the signaling pathway.
本研究的目的是阐明眼镜蛇毒磷脂酶A2（PLA2）诱导人神经母细胞瘤SK-N-SH细胞死亡所涉及的信号通路。将SK-N-SH细胞暴露于PLA2后，发现细胞中p38丝裂原活化蛋白激酶（MAPK）激活、细胞外调节蛋白激酶（ERK）失活、活性氧（ROS）生成、细胞内钙离子（Ca2+）浓度升高以及Fas和Fas配体（FasL）上调。SB202190（p38 MAPK抑制剂）抑制了Fas和FasL的上调。N-乙酰半胱氨酸（ROS清除剂）和1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸四乙酰甲酯（BAPTA-AM，Ca2+螯合剂）消除了p38 MAPK激活以及Fas和FasL表达的上调，但恢复了ERK磷酸化。发现活化的ERK可减弱p38 MAPK介导的Fas和FasL上调。催化活性的缺失并不能减少PLA2诱导的细胞死亡以及Fas/FasL上调。此外，花生四烯酸和溶血磷脂酰胆碱的细胞毒性与Fas和FasL的表达无关。综上所述，我们的结果表明，PLA2诱导细胞死亡部分是由Fas和FasL上调引发的，而Fas和FasL上调由Ca2+和ROS诱发的p38 MAPK激活所调节，并提示非催化性PLA2在该信号通路中发挥作用。
