Role of endoplasmic reticulum calcium in beta cell mitochondrial dysfunction, senescence, and onset of type 1 diabetes

项目摘要/摘要 1型糖尿病(T1D)的特征是自身免疫介导的产生胰岛素的β细胞被破坏 胰腺会导致严重的高血糖。最近的证据表明，β细胞本身扮演着一个复杂的角色 通过激活细胞衰老在T1D发病中的作用，这与分泌 趋化因子和促炎细胞因子(SASP)可能起到放大免疫细胞募集的作用， 使β细胞更容易受到免疫攻击。而衰老与线粒体有关 在其他类型的细胞中，导致β细胞衰老和SASP的分子通路在很大程度上是 未知，因此迫切需要确定推动新型T1D开发的潜在机制 预防疗法。钙(Ca~(2+))在β细胞功能中起着至关重要的作用，调节参与 胰岛素的产生和分泌。这些任务的保真度取决于钙存储的维护， 在细胞和细胞器水平上都有组织。内质网(ER)起主导作用 细胞内钙离子储存，内质网钙离子通过肌浆网钙离子活性维持 ATPase 2b(SERCA2)泵。我们以前已经证明，在模型中β细胞SerCA2的表达降低 导致胰岛素分泌减少，内质网应激，并增加β细胞死亡。我的初步数据显示 延长了这些观察结果，并将SERCA2活性的丧失与线粒体功能和 关键衰老标志物的表达增加。在此背景下，我假设ER的损失 Ca~(2+)通过减少SERCA~(2+)促进β细胞衰老，并通过线粒体功能障碍促进SASP细胞衰老 推动T1D发展。我将通过两个具体目标来检验这一假设。在目标1中，我将澄清 内质网钙离子丢失对胰岛β细胞衰老、SASP和线粒体功能的影响在目标2中，我将定义 SERCA2激活和/或衰老处理(消除衰老细胞)是否能减弱T1D 发病时，β细胞线粒体功能障碍、衰老和SASP。这个项目的完成有可能 明确β细胞内质网钙离子和线粒体健康在T1D和T1D发育过程中的新调节作用 可能为预防T1D提供新的范例。有了F31博士前奖学金，我将有权 完成我的研究战略，同时专注于我的培训计划，包括4个主要目标：1) 建立对糖尿病研究中的技术和概念的详细和基础的理解，2)建立 较强的活细胞成像和单细胞核糖核酸测序分析技能，3)开发和培养 指导技能，以及4)通过书面和口头的科学交流提高我的批判性思维能力。 我的培训计划将得到经验丰富的教师和提供的合作研究环境的支持 印第安纳大学糖尿病和新陈代谢疾病中心和赫尔曼·B·威尔斯中心 医学院。总而言之，这一全面的研究战略和培训计划将使我 在T1D研究领域产生持久影响的轨迹。

PROJECT SUMMARY / ABSTRACT Type 1 diabetes (T1D) is characterized by autoimmune-mediated destruction of the insulin producing β cells of the pancreas causing severe hyperglycemia. Recent evidence suggests that the β cell itself plays a complex role in T1D pathogenesis through activation of cellular senescence, which is associated with secretion of chemokines and proinflammatory cytokines (SASP) that may act to amplify recruitment of immune cells, making the β cells more vulnerable to immune attack. While senescence has been linked with mitochondrial dysfunction in other cell types, the molecular pathways leading to β cell senescence and SASP are largely unknown, leaving a critical need to determine underlying mechanisms to propel the development of novel T1D prevention therapeutics. Calcium (Ca2+) plays a vital role in β cell function, regulating key steps involved in the production and secretion of insulin. The fidelity of these tasks depends on the maintenance of Ca2+ stores, organized at both the cellular and organelle level. The endoplasmic reticulum (ER) serves as a dominant intracellular Ca2+ store, and ER Ca2+ is maintained through activity of the sarco-endoplasmic reticulum Ca2+ ATPase 2b (SERCA2) pump. We have shown previously that β cell SERCA2 expression is reduced in models of T1D, leading to diminished insulin secretion, ER stress, and increased β cell death. My preliminary data has extended these observations and linked loss of SERCA2 activity with decreased mitochondrial function and increased expression of key senescence markers. Against this background, I hypothesize that loss of ER Ca2+ via reduced SERCA2, accelerates β cell senescence and SASP via mitochondrial dysfunction driving the development of T1D. I will test this hypothesis through two specific aims. In Aim 1, I will elucidate the role of ER Ca2+ loss on islet β cell senescence, SASP, and mitochondrial function. In Aim 2, I will define whether SERCA2 activation and/or senolytic treatments, which eliminate senescent cells, can attenuate T1D onset, β cell mitochondrial dysfunction, senescence, and SASP. Completion of this project has the potential to define a novel regulatory role for β cell ER Ca2+ and mitochondrial health during the development of T1D and may inform new paradigms of T1D prevention. With this F31 Predoctoral Fellowship, I will be empowered to complete my research strategy, while also focusing on my training plan, which includes 4 main objectives: 1) Build a detailed and foundational understanding of techniques and concepts in diabetes research, 2) Build strong technical skills in live cell imaging and single cell RNA sequencing analysis, 3) Develop and cultivate mentoring skills, and 4) Enhance my critical thinking skills through written and oral scientific communication. My training plan will be supported by the experienced faculty and collaborative research environment provided by the Center for Diabetes and Metabolic Diseases and Herman B. Wells Center at the Indiana University School of Medicine. In summary, this comprehensive research strategy and training plan will set me on a trajectory to make a lasting impact in the field of T1D research.