Role of Circadian Misalignment in Beta-cell Failure in Type 2 Diabetes

项目摘要/摘要 胰腺β细胞衰竭是2型糖尿病(T2 DM)的一个显著特征，因此保存 β-细胞健康已被确定为成功预防和治疗发展的关键障碍 2型糖尿病的治疗策略。β细胞衰竭的主要特征包括胰岛素分泌功能障碍，转录缺失 Identity/β细胞去分化和β细胞丢失，越来越多的证据表明内质网受损 (Er)蛋白质调控是这一过程的关键驱动因素。最近的证据表明，环境压力条件 造成日常禁食/进食昼夜节律紊乱(即昼夜节律紊乱，CD)导致血糖 不耐受、高血糖，并促进T2 DM的β细胞衰竭。然而，潜在的分子机制 β细胞功能和内质网蛋白平衡的昼夜节律调控仍不清楚。在这方面，我们的初步研究 确定CD介导的正常禁食/进食周期的取消是β的有效生理诱因- 细胞功能衰竭，这一过程是通过β-细胞表达/活性的丧失而分子介导的 昼夜节律转录因子D-box结合PAR bZIP转录因子(DBP)。因此，关键目标是 这项提议是为了检验这一假设，即DBP是β细胞昼夜节律功能的重要调节因子 调节胰岛素分泌和ER蛋白稳定的转录本的节律性激活，而DBP的丢失 β细胞对昼夜节律紊乱和饮食诱导的肥胖的反应，促进β细胞的表达 2型糖尿病患者功能减退。为了解决这一问题，特定目标1将利用新的条件遗传损失和获得- 建立DBP小鼠模型以建立昼夜节律性DBP表达与 β细胞功能、内质网蛋白平衡和转录特性的调节。此外，我们还将审查 DBP是否利用病毒功能的得失来调节β细胞的功能和在人β细胞中的转录 将人类干细胞来源的β细胞移植到免疫缺陷小鼠体内的同时技术。 特殊目标2将利用β细胞特异的DBP荧光素酶报告鼠和系统生物学多组学方法 (RNAseq ScATAC Seq)以1)确定肥胖扰乱昼夜节律的分子机制 DBP表达和相应的β细胞昼夜节律时钟功能，以及2)测试旨在 在肥胖患者中恢复β细胞生物钟的正常功能，作为预防T2 DM患者β细胞衰竭的手段。已被占用 总之，拟议研究的成功完成将揭示新的分子机制，通过这些机制，β- 细胞整合并对营养供应的昼夜变化做出反应，并将提供潜在的治疗 2型糖尿病的防治目标。

PROJECT SUMMARY/ABSTRACT Pancreatic β-cell failure in a distinctive feature of Type 2 diabetes mellitus (T2DM) and therefore preservation of β-cell health has been identified as a critical barrier for the development of successful preventative and treatment strategies in T2DM. Primary features of β-cell failure include insulin secretory dysfunction, loss of transcriptional identity/β-cell dedifferentiation, and β-cell loss, with growing evidence pointing to impaired endoplasmic reticulum (ER) proteostasis as a key driver of this process. Recent evidence suggests that environmental stress conditions that produce disruptions of daily fasting/feeding circadian cycles (i.e. circadian disruption, CD) lead to glucose intolerance, hyperglycemia, and promote β-cell failure in T2DM. However, the molecular mechanisms underlying circadian control of β-cell function and ER proteostasis remain unknown. In this regard, our preliminary studies determined that CD-mediated abrogation of normal fasting/feeding cycles is a potent physiological inducer of β- cell functional failure, and this process is molecularly mediated through loss of β-cell expression/activity of circadian transcription factor D-box binding PAR bZIP transcription factor (Dbp). Therefore, the key objective of the proposal is to test the hypothesis that Dbp is an important regulator of β-cell circadian function through rhythmic activation of transcripts regulating insulin secretion and ER proteostasis, whereas loss of Dbp expression, as occurs in β-cells in response to circadian disruption and diet-induced obesity, promotes β-cell functional decline in T2DM. To address this, Specific Aim 1 will utilize novel conditional genetic loss and gain-of- function Dbp mouse models to establish a causative relationship between circadian Dbp expression and the regulation of β-cell function, ER proteostasis, and transcriptional identity. In addition, we will also examine whether Dbp regulates β-cell function and transcription in human β-cells utilizing viral gain/loss of function techniques concurrent with transplantation of human stem cell-derived β-cells into immunodeficient mice. Specific Aim 2 will utilize β-cell-specific Dbp luciferase reporter mice and systems biology multiomics approaches (RNAseq + scATAC seq) to 1) identify molecular mechanisms by which obesity disrupts circadian regulation of Dbp expression and corresponding β-cell circadian clock function, and 2) test novel strategies designed to restore normal functionality of β-cell circadian clocks in obesity as means to prevent β-cell failure in T2DM. Taken together, successful completion of proposed studies will uncover novel molecular mechanisms through which β- cells integrate and respond to circadian changes in nutritional availability and will provide potential therapeutic targets for prevention and treatment of T2DM.