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Analysis of ASK1 and ASK2 as stress signaling intermediates.

分析 ASK1 和 ASK2 作为应激信号中间体。

基本信息

批准号：
10470396
负责人：
ICHIJO Hidenori
金额：
$ 8万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10470396/
关键词：
ASK1 JNK P38 Apoptosis p38 MAPキナーゼ Traf Daxx

项目摘要

Although the molecular mechanisms of execution phase of apoptosis has extensively been studied, very little is known about the induction phase or signal transduction of apoptosis. Here we investigated the molecular mechanisms of apoptosis through identifying the regulatory mechanisms of ASK1. Based on our previous findings that thioredoxin (Trx) and TRAF2 acts on ASK1 as an inhibitor and activator, respectively, we analyzed the relationship of these molecules on the ASK1 molecule. TRAF2 induced the dissociation of Trx from ASK1 in a reactive oxygen species (ROS)-dependent manner. We found that prior dissociation of Trx from ASK1 is required for TRAF2 binding to ASK1 and thereby activation of ASK1, and TRAF2 bound to ASK1 induced oligomerization of ASK1 and autophosphorylation. In addition, phosphorylation of Bcl-2 by JNK was found to be important for the ASK1-induced apoptosis. Moreover, expression of constitutively active ASK1 was found to induce neurite outgrowth in PC12 cells. We found that p38 and to a lesser extent JNK, but not ERK, were activated by the expression of active ASK1. By the treatment with a p38 inhibitor SB203580, ASK1-induced neurite outgrowth was strongly inhibited, suggesting that the activation of p38 is required for the neurite-inducing activity of ASK1. We also observed that ASK1 induced expression of several neuron-specific proteins and phophorylation of neurofilament proteins, confirming that PC12 cells differentiated into mature neuronal cells by ASK1. Moreover, ASK1-expressing PC12 cells could survive in a serum-starved condition. Therefore, ASK1 appears to mediate signals leading to both differentiation and survival in PC12 cells. Together with the previous reports indicating that ASK1 functions as a pro-apoptotic signaling intermediate, these results suggest that ASK1 has much broader range of biological activities in a cell-type specific manner than we expected before.

虽然细胞凋亡的执行阶段的分子机制已被广泛研究，但对细胞凋亡的诱导阶段或信号转导知之甚少。在此，我们通过确定ASK 1的调控机制来研究细胞凋亡的分子机制。基于我们先前的发现，硫氧还蛋白（Trx）和TRAF 2分别作为抑制剂和激活剂作用于ASK 1，我们分析了这些分子对ASK 1分子的关系。TRAF 2以活性氧（ROS）依赖的方式诱导Trx从ASK 1解离。我们发现，TRAF 2与ASK 1的结合需要Trx从ASK 1上预先解离，从而激活ASK 1，TRAF 2与ASK 1结合诱导ASK 1的寡聚化和自磷酸化。另外，JNK对Bcl-2的磷酸化在ASK 1诱导的细胞凋亡中起重要作用。此外，组成型活性ASK 1的表达被发现诱导PC 12细胞中的神经突生长。我们发现，p38和在较小程度上JNK，但不是ERK，被激活的活性ASK 1的表达。通过用p38抑制剂SB 203580处理，ASK 1诱导的神经突生长被强烈抑制，这表明p38的激活是ASK 1的神经突诱导活性所必需的。我们还观察到ASK 1诱导几种神经元特异性蛋白的表达和神经丝蛋白的磷酸化，证实了PC 12细胞通过ASK 1分化为成熟的神经元细胞。此外，表达ASK 1的PC 12细胞可以在血清饥饿条件下存活。因此，ASK 1似乎介导导致PC 12细胞分化和存活的信号。加上之前的报告表明ASK 1作为促细胞凋亡信号中间体发挥作用，这些结果表明ASK 1以细胞类型特异性方式具有比我们之前预期的更广泛的生物活性。