Benefits and harms of activating ATF6 in beta cells

摘要 胰岛β细胞胰岛素的产生是决定糖尿病抵抗或易感性的关键。 内质网应激是β细胞功能障碍和衰竭的原因之一，不仅在T2D，而且在T1D和某些形式的 单基因糖尿病。许多已发表的报道表明，ATF6通路是内质网应激的三个主要途径之一 反应通路在细胞对应激的适应中起着重要的作用。特别是，ATF6是已知的驾驶 有益的影响包括增加内质网的能力，细胞在面对压力时的存活，以及最近的证据 来自我们小组和其他几个人的研究表明，ATF6参与了胰岛素对β细胞的补偿性增殖 需求。由于这些原因，atf6的激活被认为是一种潜在的β细胞治疗方法。 这可能会提高β细胞的质量和胰岛素的生产能力。我们开发了两个新颖的、令人兴奋的工具 这使我们能够在时间上精确地激活β细胞中的ATF6，无论是在体外还是在活体小鼠体内。首字母 然而，实验表明，当我们在很长一段时间内不加区别地激活ATF6时，我们 观察有益和有害的混合影响，在某些方面让人想起糖毒性β细胞衰竭。 具体地说，我们确实观察到了β细胞增殖和存活增加的证据，但在体内激活了ATF6 连续服用14天会导致由于β细胞功能障碍而导致的直白的葡萄糖耐量减低。值得注意的是，如果 我们允许ATF6关闭，β细胞功能逐渐恢复正常。分子和形态初步研究 数据表明，在体内慢性持续激活ATF6在许多方面模仿了慢性β细胞应激在 T2D，与老鼠和人类的观察相似。因此，这种模式代表了一个巨大的 研究慢性激活一种内质网应激反应后β细胞衰竭的直接原因的机会 途径(ATF6)，以及一个独特而令人兴奋的机会来了解体内的恢复过程，如果应激 通路的激活能够关闭。在这个项目中，我们将探索ATF6后β细胞衰竭的原因 激活，通过深入的分子、形态和组织动态平衡实验。我们将确定 当ATF6被允许关闭时，用于恢复β细胞的细胞和分子基础。最后，我们将注意力转向 ATF6激活的益处和危害的分子机制，并试图确定在 哪些有益的反应可以与有害的反应分开，看看是否有可能在 未来利用ATF6在糖尿病治疗或预防中具有安全的治疗潜力。如果成功，这将是 该项目将为β细胞应激诱导的糖尿病，体内恢复过程带来重要的新见解 ATF6诱导的β细胞功能障碍，ATF6驱动益处和伤害的分子机制，以及 是否有可能为了未来的治疗利益而将利与害分开。

ABSTRACT Pancreatic beta cell insulin production is the critical lynchpin that determines diabetes resistance or susceptibility. ER stress is one cause of beta cell dysfunction and failure, not only in T2D but also in T1D and some forms of monogenic diabetes. Many published reports show that the ATF6 pathway, one of three principal ER stress response pathways, plays important roles in cellular adaptation to stress. In particular, ATF6 is known to drive beneficial effects including increased ER capacity, cell survival in the face of stress, and more recently evidence from our group and several others implicate ATF6 in beta cell compensatory proliferation in response to insulin demand. For these reasons, activation of ATF6 has been proposed as a potential beta cell therapeutic approach that might improve beta cell mass and insulin production capacity. We have developed two novel, exciting tools that allow us to activate ATF6 in beta cells with temporal precision, either ex vivo or in vivo in live mice. Initial experiments, however, show that when we indiscriminately activate ATF6 for an extended period of time we observe a mix of beneficial and harmful effects, in some ways reminiscent of glucotoxic beta cell failure. Specifically, we do observe evidence of increased beta cell proliferation and survival, but activating ATF6 in vivo continuously for a 14-day period leads to frank glucose intolerance due to beta cell dysfunction. Remarkably, if we allow ATF6 to turn off, beta cell function gradually returns to normal. Molecular and morphological preliminary data suggest that in vivo chronic continuous ATF6 activation mimics, in many ways, chronic beta cell stress in T2D, with similarities to mouse and human observations. As such, this model represents a tremendous opportunity to study the proximate causes of beta cell failure after chronic activation of one ER stress response pathway (ATF6), as well as a unique and exciting chance to understand the in vivo recovery process if that stress pathway activation is able to shut off. In this project we will explore the causes of beta cell failure after ATF6 activation, with in-depth molecular, morphological and tissue homeostasis experiments. We will determine the cellular and molecular bases for beta cell recovery when ATF6 is allowed to turn off. Finally, we turn our attention to the molecular mechanisms driving benefits and harms of ATF6 activation and seek to identify conditions in which beneficial responses can be separated from harmful responses, to see whether it may be possible in the future to harness ATF6 for safe therapeutic potential in diabetes treatment or prevention. If successful, this project will lead to important new insight into beta cell stress-induced diabetes, the in vivo recovery process after ATF6-induced beta cell dysfunction, the molecular mechanisms by which ATF6 drives benefits and harms, and whether it may be possible to separate benefit from harm for future therapeutic benefit.