Harnessing the Adaptive ER Stress Response in Myocardial Ischemia

项目摘要 心肌缺血导致内质网应激和潜在致命性的内质网蛋白错误折叠。适应性内质网应激 Response可恢复ER蛋白折叠并促进心肌细胞存活。如果此过程不足以恢复ER 蛋白质折叠，随之而来的不适应内质网应激反应导致心肌细胞死亡。在低氧环境中生存 在肿瘤环境中，癌细胞已经进化出一种夸大的适应性内质网应激反应，介导 部分是由转录因子ATF6激活的，它被内质网应激激活。与癌细胞相比，正常细胞 有相对较少的ATF6和弱的适应性内质网应激反应。我们的初步数据显示，ATF6 基因缺失增加了心肌梗死小鼠的心肌梗死面积，降低了其功能。这个 这项研究的目的是研究ATF6在心脏中发挥作用的分子机制。 这将揭示基于以下因素开发缺血性心脏病新疗法所需的新信息 利用心脏的适应性内质网应激反应。在我们之前的研究中，我们惊讶地发现 这种被激活的ATF6被迅速降解；这种在激活时降解的特性表明，对 ATF6的水平及其调节的基因必须具有功能意义；然而，这种意义具有 没有经过检查。我们的假设如下：1-内源性ATF6适应性地减少细胞凋亡和 缺血时的心肌梗死范围，可促进缺血后心肌恢复。2-ATF6在以下情况下降级 激活是因为短期的ATF6激活是适应性的，而长期的ATF6激活是非适应性的。3- 用小分子激活剂激活内源性ATF6是适应性的，因为它是可逆的，所以我们可以 调整剂量和时间以最大限度地适应和最大限度地减少ATF6激活的不良适应影响以优化 治疗潜力。这三个假设将通过以下相应的具体目标加以解决： 1-在心肌梗塞模型中评估内源性ATF6缺失对心脏结构和功能的影响 使用ATF6基因敲除(KO)小鼠的心力衰竭。2-使用AAV9介导的ATF6基因转移 向ATF6 KO小鼠展示一系列降解后的活动特性，然后评估这些形式的影响 ATF6对心力衰竭心肌梗死模型心脏结构和功能的影响3-确定小说的效果 小分子激活剂对内源性ATF6活性和内质网应激信号的影响 心肌细胞，然后和在小鼠体内。

Project Summary Myocardial ischemia causes ER stress and potentially lethal ER protein misfolding. The adaptive ER stress response restores ER protein folding and fosters myocyte survival. If this process is not sufficient to restore ER protein folding, the ensuing maladaptive ER stress response leads to myocyte death. To survive the hypoxic environment in tumors, cancer cells have evolved an exaggerated adaptive ER stress response, mediated partly by the transcription factor, ATF6, which is activated by ER stress. Compared to cancer cells, normal cells have relatively little ATF6 and a weak adaptive ER stress response. Our preliminary data showed that ATF6 deletion increased infarct size and decreased function in mouse hearts subjected to myocardial infarction. The objective of the proposed research is to examine the molecular mechanism of ATF6 function in the heart, which will reveal new information needed to develop novel therapies for ischemic heart disease based on harnessing the adaptive ER stress response in the heart. In our previous studies, we were surprised to find that activated ATF6 is rapidly degraded; this degraded-when-active property suggests that strict regulation of the level of ATF6 and the genes it regulates, must have functional significance; however, this significance has not been examined. Our hypotheses are as follows: 1- Endogenous ATF6 adaptively decreases apoptosis and infarct size upon ischemia, which improves post-ischemia myocardial recovery. 2- ATF6 is degraded when active because short-term ATF6 activation is adaptive, while long-term ATF6 activation is maladaptive. 3- Activation of endogenous ATF6 with small molecule activators is adaptive, and because it is reversible, we can regulate dose and time to maximize adaptive and minimize maladaptive effects of ATF6 activation to optimize therapeutic potential. These three hypotheses will be addressed by the following corresponding Specific Aims: 1- To assess the effects of endogenous ATF6 deletion on cardiac structure and function in an MI model of heart failure using ATF6 knockout (KO) mice. 2- To use AAV9-mediated gene transfer of forms of ATF6 that exhibit a range of degraded-when-active properties into ATF6 KO mice, then assess the effects of these forms of ATF6 on cardiac structure and function in an MI model of heart failure. 3- To determine the effects of novel small molecule activators of endogenous ATF6 on the viability and on ER stress signaling, initially in isolated cardiac myocytes and then and in mice, in vivo.