Zhao Sheng, Yang Ya-Nan, Song Jian-Guo
Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
J Cell Physiol. 2004 Apr;199(1):47-56. doi: 10.1002/jcp.10453.
We investigated the ceramide-induced apoptosis and potential mechanism in A-431 cells. Ceramide treatment causes the round up and the death of A-431 cells that is associated with p38 activation and can be observed in 10 h. Short-time ceramide treatment-induced cell death is not associated with the typical apoptotic phenotypes, such as the translocation of phosphatidylserine (PS) from inner layer to outer layer of the plasma membrane, loss of mitochondrial membrane potential, DNA fragmentation, caspase activation, and PARP or PKC-delta degradation. SB202190, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, but not caspase inhibitor, blocks the cell death induced by short-time ceramide treatment (within 12 h). Whereas neither inhibition of p38 MAP kinase nor inhibition of caspases blocks cell death induced by prolonged ceramide treatment. Moreover, incubation of cells with ceramide for a long time (over 12 h) results in the reduction of proportion of S phase accompanied with typical apoptotic cell death phenotypes that are different from the cell death induced by short-time ceramide treatment. Our data demonstrated that ceramide-induced apoptotic cell death involves both caspase-dependent and caspase-independent signaling pathways. The caspase-independent cell death that occurred in relatively early stage of ceramide treatment is mediated via p38 MAP kinase, which can progress into a stage that is associated with changes of cell cycle events and involves both caspase-dependent and -independent mechanisms.
我们研究了神经酰胺诱导A-431细胞凋亡及其潜在机制。神经酰胺处理导致A-431细胞变圆并死亡，这与p38激活相关，且在10小时内即可观察到。短时间神经酰胺处理诱导的细胞死亡与典型的凋亡表型无关，如磷脂酰丝氨酸（PS）从质膜内层向外层的易位、线粒体膜电位丧失、DNA片段化、半胱天冬酶激活以及PARP或PKC-δ降解。p38丝裂原活化蛋白（MAP）激酶的特异性抑制剂SB202190可阻断短时间神经酰胺处理（12小时内）诱导的细胞死亡，但半胱天冬酶抑制剂则不能。然而，抑制p38 MAP激酶或抑制半胱天冬酶均不能阻断长时间神经酰胺处理诱导的细胞死亡。此外，长时间（超过12小时）用神经酰胺孵育细胞会导致S期比例降低，并伴有典型的凋亡细胞死亡表型，这与短时间神经酰胺处理诱导的细胞死亡不同。我们的数据表明，神经酰胺诱导的凋亡细胞死亡涉及半胱天冬酶依赖性和非依赖性信号通路。在神经酰胺处理相对早期发生的非半胱天冬酶依赖性细胞死亡是通过p38 MAP激酶介导的，其可进展到一个与细胞周期事件变化相关的阶段，且涉及半胱天冬酶依赖性和非依赖性机制。
