Molecular mechanism of CHOP dependent cell death induced by extracellular stresses

细胞外应激诱导CHOP依赖性细胞死亡的分子机制

基本信息

批准号：
16590057
负责人：
HAYASHI Hidetoshi
金额：
$ 2.3万
依托单位：
Nagoya City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16590057/
关键词：
TRB3 CHOP ATF4 p300 endoplasmic reticulum stress apoptosis diabetes neurodegenerative diseases ネガティブ・フィードバック Akt

项目摘要

The endoplasmic reticulum(ER) stress is induced by the accumulation of misfolding or malfolding proteins in ER caused by genetic mutation or abnormal modification of proteins. Recently, it is clarified that the ER stress-induced apoptosis cause the neurodegenerative diseases and the diabetes. Applicants are advancing the study of analysis on transcription factor CHOP to which are induced at the ER stress, and are related of apoptosis. Here we have shown that the TRB3, one of the human homologs of a Drosophila kinase like molecule Tribbles, is induced by ER stress and its promoter is activated via ER stress-induced transcription factors, CHOP and ATF4. TRB3 proteins suppress the transcriptional activities of CHOP and ATF4, suggesting CHOP(probably also ATF4)signaling is strictly regulated by TRB3 via a negative feedback mechanism.In addition, overexpression of TRB3 enhances the ER stress-induced cell death, while the knockdown of TRB3 by a siRNA method decreased the cell death. We have … More also observed the association between TRB3 and CHOP by the immunoprecipitaion-Western blot methods. Inhibitory effect of TRB3 on the transcriptional activity of CHOP is Independent of protein degradation. Moreover, the expression of TRB3 did not influence the dimer formation and DNA binding activities of CHOP. However, TRB3 associated with CHOP through its transcriptional domain and this domain is overlapped with a p300 binding domain. Overexpression of TRB3 remarkably inhibited the formation of p300-CHOP complex. These results suggest that TRB3 may function as an antagonist to replace the p300 from CHOP, and control its transcriptional effect. Moreover, transactivational activity of ATF4 is also suppressed by TRB3 probably by the decrease in its stability and by the dissociation of p300 from ATF4.It is well known that some products necessary for cell survival are the downstream targets of ATF4, suggesting that the downregulation of ATF4 by TRB3 may greatly contribute the apoptosis according to the ER stress. Less

内质网(ER)应激是由基因突变或蛋白质异常修饰引起的错误折叠或畸形折叠蛋白在ER中的积累而引起的，最近，申请人阐明了ER应激诱导的细胞凋亡导致神经退行性疾病和糖尿病。正在推进对转录因子 CHOP 的分析研究，该转录因子在 ER 应激下被诱导，并且与细胞凋亡相关。在这里，我们证明了 TRB3（果蝇的人类同源物之一）。激酶样分子 Tribbles 是由 ER 应激诱导的，其启动子是通过 ER 应激诱导的转录因子 CHOP 和 ATF4 激活的，TRB3 蛋白抑制 CHOP 和 ATF4 的转录活性，表明 CHOP（可能也是 ATF4）信号传导受到严格调控。 TRB3通过负反馈机制。此外，TRB3的过表达增强了ER应激诱导的细胞死亡，而通过siRNA方法敲低TRB3则减少了细胞死亡。我们还通过免疫沉淀-Western印迹方法观察到TRB3和CHOP之间的关联，TRB3对CHOP转录活性的抑制作用与蛋白质降解无关。然而，TRB3 通过其转录结构域与 CHOP 相关，并且该结构域与 p300 结合结构域重叠，TRB3 的过表达单独抑制了 CHOP 的形成。这些结果表明，TRB3 可能作为拮抗剂取代 CHOP 的 p300，并控制其转录作用。此外，TRB3 的反式激活活性也可能受到 TRB3 稳定性降低和解离的抑制。众所周知，细胞生存所必需的一些产物是ATF4的下游靶标，这表明TRB3对ATF4的下调可能极大地促进细胞凋亡根据 ER 压力较小。