Structural Insights to Insulin Receptor Ligand Interactions

摘要 胰岛素治疗可以显著改善糖尿病患者的健康状况，并且通常每天服用。 长效胰岛素和餐时速效胰岛素。尽管取得了相当大的成功，但一些重要的 挑战依然存在，包括本提案中提到的三个主要限制因素。首先，即使是最好的 临床上可获得的速效胰岛素太慢且持续太长时间而不能提供对血清葡萄糖的严格控制 在生理范围内，导致实质性偏离该范围和慢性高血糖症 或急性低血糖并发症。其次，目前可用的胰岛素需要持续冷藏，以避免 聚集，而不需要冷链递送的治疗性胰岛素将提供相当大的 优点，特别是用于长期胰岛素泵和在电力被消耗的情况下， 不可靠第三，因为胰岛素刺激两种信号，一种对代谢控制有利 (Akt途径）和一种治疗上涉及促有丝分裂生长（Erk途径）， 开发优先刺激Akt途径的类似物。这项提案需要一种生物化学和 以结构为基础的方法，以获得对这些问题中的每一个的机械见解，包括冷冻EM结构 受体-配体复合物的测定，辅之以多种方法，包括细胞信号传导 和小鼠葡萄糖反应性研究。目的1集中在两个人源化变异的锥蜗牛毒液 胰岛素，其缺乏使天然胰岛素二聚体化的残基，并且固有地对皮下胰岛素作用缓慢， 注射，并已被工程化以提供快速反应、短作用持续时间和高效力。目的2 重点是使胰岛素抵抗聚集/纤维化的方法，包括跟踪 令人惊讶的发现是，一种人源化的毒液胰岛素对聚集具有高度抗性。Aim 3探索 一些受体配体引起偏向性信号传导的显著特性，该信号传导强调Akt或 Erk途径，并提供了解这些影响的结构基础的潜力。实现这些目标 将提供基本的机制见解，并为开发改进的治疗方法提供信息。

ABSTRACT Insulin treatment dramatically improves the health of people with diabetes, and is usually administered as a daily long-acting insulin and a prandial fast-acting insulin. Despite considerable success, a number of important challenges remain, including three major limitations that are addressed in this proposal. First, even the best clinically-available fast-acting insulins are too slow and last too long to provide tight control of serum glucose within the physiological range, resulting in substantial excursions outside of this range and chronic hyperglycemia or acute hypoglycemic complications. Second, currently available insulins require continual refrigeration to avoid aggregation, whereas therapeutic insulins that do not require cold-chain delivery would offer considerable advantages, especially for use in long-term insulin pumps and in circumstances where electrical power is unreliable. Third, because insulin stimulates two signals, one therapeutically advantageous for metabolic control (Akt pathway) and one therapeutically concerning for mitogenic growth (Erk pathway), there is interest in developing analogs that preferentially stimulate the Akt pathway. This proposal takes a biochemical and structure-based approach to gain mechanistic insight to each of these concerns, including cryo-EM structure determination of receptor-ligand complexes complemented by a variety of approaches, including cell signaling and mouse glucose-responsiveness studies. Aim 1 focusses on two humanized variants of cone snail venom insulins, which lack residues that make native insulin dimeric and inherently slow acting upon subcutaneous injection, and have been engineered to provide fast response, short duration of action, and high potency. Aim 2 focusses on approaches to render insulins resistant to aggregation/fibrillation, including following up on the surprising finding that one of the humanized venom insulins is highly resistant to aggregation. Aim 3 explores the remarkable property of some receptor ligands to elicit biased signaling that emphasizes either the Akt or the Erk pathways, and offers potential to understand the structural basis for these effects. Completion of these aims will provide fundamental mechanistic insights and inform efforts to develop improved therapeutics.