Tumor necrosis factor alpha signaling pathway and apoptosis in pancreatic beta cells.
Tumor necrosis factor alpha signaling pathway and apoptosis in pancreatic beta cells.
复制标题
肿瘤坏死因子α信号通路和胰腺β细胞凋亡。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
A. Kanatsuka
中科院分区：
文献类型：
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作者：
N. Ishizuka;K. Yagui;Y. Tokuyama;K. Yamada;Y. Suzuki;J. Miyazaki;N. Hashimoto;H. Makino;Y. Saito;A. Kanatsuka
Cytokines induce apoptosis in pancreatic beta cells, but the exact mechanisms and sequence of events are not clear. Here, we investigate a role for tumor necrosis factor alpha (TNF-alpha) in the apoptosis of beta cells. Using the ribonuclease (RNase) protection assay and the reverse transcriptase-polymerase chain reaction (RT-PCR) method, we confirmed that TNF receptor 1 (TNFR1), TNFR1-associated death domain protein (TRADD), Fas receptor-associated intracellular protein with death domain (FADD), and FADD-like interleukin-1beta-converting enzyme (FLICE) were expressed in the pancreatic beta cell line, MIN6 cells. Fluorescent microscopic examination using Hoechst 33342 dye (Sigma, St Louis, MO) demonstrated that TNF-alpha induced time- and dose-dependent apoptotic nuclear changes in these beta cells. In situ end-labeling (ISEL) DNA analysis revealed that 10 nmol/L TNF-alpha generated new 3'-OH DNA strand breaks. Moreover, qualitative assessment of the induced DNA damage on agarose gels showed that 10 nmol/L TNF-alpha produced characteristic apoptotic patterns of DNA fragments formed by internucleosomal hydrolysis of static chromatin. In addition, C2-ceramides and natural ceramides dispersed in a solvent mixture of ethanol and dodecane induced characteristic features of apoptosis in MIN6 cells, mimicking TNF-induced DNA damage. We also determined endosomal ceramide production after TNF-alpha (10 nmol/L) treatment in MIN6 cells using the diacylglycerol kinase assay. These results suggest that TNF-alpha can cause apoptosis in pancreatic beta cells through TNFR1-linked apoptotic factors, TRADD, FADD, and FLICE, and TNF-induced ceramide production may be involved in the pathways.
