Developing proinsulin misfolding inhibitors for beta cell protection and diabetes treatment

摘要 胰腺β细胞的功能障碍和死亡是所有类型糖尿病的关键特征。最近有 表明胰岛素原错误折叠的增加发生在糖尿病发作之前， 在糖尿病中，包括内质网（ER）应激在内的事件导致β细胞功能障碍和死亡。那里 目前没有抑制胰岛素原错误折叠的干预手段。在初步研究中，我们 发现了一种小分子（命名为PTTD），可保护β细胞免受高浓度内质网应激诱导的死亡。 吞吐量屏幕。我们发现PTTD抑制了ER应激诱导的所有三种细胞的激活， ER应激下β细胞中未折叠蛋白反应（UPR）途径的分支（IRE 1、PERK和ATF 6）。 然后我们观察到PTTD消除了错误折叠的胰岛素原的积累，同时增加了成熟的胰岛素。 β细胞中胰岛素产生和PTTD抑制细胞中纯化的胰岛素蛋白的错误折叠/聚集， 免费生化分析。重要的是，在体内动物研究中，PTTD显著改善高血糖症 在多个小鼠糖尿病模型的β细胞衰竭。这些令人兴奋的结果表明， 通过PTTD的胰岛素原错误折叠保护β细胞并改善糖尿病。在这个应用程序中，我们将使用PTTD 作为起始分子开发作为一流的胰岛素原错误折叠抑制剂的有效类似物。实现 为此，我们将使用一种方法，将迭代和平行的药物化学与体外和体内 疗效和DMPK研究具有特定目的。在目标1中，我们将改进和优化我们的先导化合物， PTTD，通过基于药物化学的构效关系研究。在目标2中，具有以下结构的化合物： 将使用标准化的ADMET对提高的效价进行理化表征和分析 和体内PK测定。在目标3中，我们将在两个孔中评估先导PTTD类似物的体内功效。 建立了胰岛素原错误折叠和进行性β细胞丢失的糖尿病模型。这项工作的完成将 不仅将PTTD及其类似物鉴定为β细胞胰岛素原错误折叠的一流化学抑制剂， 保护，而且还建立了抑制胰岛素原错误折叠作为一个新的治疗方向， 糖尿病，这将作为一个基础，并提供一个先导化合物，可能会指导进一步发展， 胰岛素原折叠疗法。

Abstract The dysfunction and death of pancreatic β cells are key features in all types of diabetes. It was recently shown that increased proinsulin misfolding occurs well before the onset of diabetes and is responsible for events, including endoplasmic reticulum (ER) stress, leading to β-cell dysfunction and death in diabetes. There is currently no interventional means that suppresses proinsulin misfolding. In our preliminary studies, we identified a small molecule (named as PTTD) that protects β-cells from ER stress-induced death in a high- throughput screen. We discovered that PTTD suppressed the ER stress-induced activation of all three branches (IRE1, PERK, and ATF6) of unfolded protein response (UPR) pathways in β-cells under ER stress. We then observed that PTTD eliminated the accumulation of misfolded proinsulin while increasing mature insulin production in β-cells and that PTTD suppressed purified insulin protein misfolding/aggregation in cell- free biochemical assays. Importantly, in in vivo animal studies, PTTD significantly ameliorated hyperglycemia in multiple mouse diabetes models of β-cell failure. These exciting results demonstrate that suppression of proinsulin misfolding by PTTD protects β-cells and ameliorates diabetes. In this application, we will use PTTD as the starting molecule to develop potent analogs as first-in-class proinsulin misfolding inhibitors. To achieve this, we will use an approach that integrates iterative and parallel medicinal chemistry with in vitro and in vivo efficacy and DMPK studies with specific aims. In Aim 1, we will improve and optimize our lead compound, PTTD, through medicinal chemistry-based structure-activity relationship studies. In Aim 2, compounds with improved potency will be characterized physicochemically and pharmacologically using standardized ADMET and in vivo PK assays. In Aim 3, we will evaluate the in vivo efficacy of lead PTTD analogs in two well- established diabetes models of proinsulin misfolding and progressive β cell loss. Completion of this work will not only identify PTTD and its analogs as first-in-class chemical suppressors of proinsulin misfolding for β-cell protection, but also establish the suppression of proinsulin misfolding as a new therapeutic direction for diabetes, which will serve as a foundation and provide a lead compound that may guide further development of proinsulin folding therapeutics.