Novel Regulators of Beta Cell Proliferation and Function

β细胞增殖和功能的新型调节剂

• 批准号: 10513301
• 负责人: Vijay K Yechoor
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2025-09-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10513301
• 关键词: Address; Adult; Age; Aging; American; Apoptosis; Beta Cell; Cell Differentiation process; Cell Maintenance; Cell Maturation; Cell Proliferation; Cell physiology; Cells; Cessation of life; Compensation; Data; Diabetes Mellitus; Embryo; Endocrine; Enhancers; Failure; Functional disorder; General Population; Genes; Genetic; Genetic Transcription; Glucose; Glucose Intolerance; Goals; High Fat Diet; Human; Impairment; Incidence; Insulin; Insulin Resistance; Knowledge; Mediating; Metabolic; Metabolic stress; Molecular; Molecular Target; Morbidity - disease rate; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nuclear; Nuclear Translocation; Obesity; Pancreas; Pathway interactions; Phenotype; Phosphorylation; Phosphotransferases; Predisposition; Process; Proliferating; Regulation; Reporting; Rest; Role; System; Testing; Transcriptional Activation; Transcriptional Regulation; Translating; Veterans; beta cell replacement; cell replacement therapy; cell type; cofactor; diabetes mellitus therapy; diabetes risk; druggable target; experimental study; functional decline; gain of function; improved; in vivo; induced pluripotent stem cell; insulin secretion; islet; islet stem cells; loss of function; military veteran; mortality; mouse model; mutant; novel; novel therapeutics; overexpression; preservation; prevent; progenitor; response; stress state; transcription factor; translational therapeutics

Diabetes is one of the leading causes of morbidity and mortality in the veteran population. The Veteran population are particularly susceptible for diabetes, with a staggering 70% of Veterans at risk for diabetes. 25% of all Veterans have diabetes, similar to that seen in older Americans from the general population. A failure to increase the β-cell proliferation and functional β-cell mass in response to increasing metabolic demand from insulin resistance associated with obesity and aging, underlies most causes of adult onset diabetes in veterans. It is, therefore, imperative to identify pathways that regulate functional β-cell mass that could be leveraged for treating β-cell failure and diabetes. Our data demonstrate that Tead1, a critical transcriptional effector of the mammalian Hippo pathway, is robustly expressed in mouse and human islets and has a non- redundant role in regulating β-cell proliferation and function. The mammalian Hippo-Tead1 pathway consists of a core kinase cascade, culminating with Lats1&2, inhibitory kinases, that phosphorylate coactivators, Yap and Taz, preventing their nuclear translocation and co-activation of Tead1-mediated transcription regulating cell proliferation and apoptosis. The premise for this proposal rests on our preliminary data that strongly suggest that Tead1 is the switch regulating the proliferation restriction, while promoting mature function in adult β-cells. Recent reports have found some contrasting results, wherein, (a) Yap-Tead1 act as an enhancer in many β- cell maturation genes in human embryonic pancreatic progenitors, (b) Yap has also been shown to inhibit endocrinogenesis in mice, and acquisition of mature function during differentiation of human iPS cells (hIPSCs), but (d) sufficient to induce proliferation in human islets, ex vivo. Preliminary data shows that β-cell specific Tead1 deletion leads to diabetes and glucose intolerance. Tead1-null islets display a decrease in expression of mature β-cell markers and a loss of glucose stimulated insulin secretion. Furthermore, our data indicates that embryonic Tead1 deletion in β-cells also led to profound diabetes suggesting that Tead1 is required in the endocrine progenitors for normal differentiation. To comprehensively test the regulation of β-cell differentiation, proliferation and function by the Hippo-tead1 pathway, we hypothesize that Tead1 regulates β-cell proliferation and acquisition of mature function via context-dependent co-factor specific, transcriptional regulation of a network of proliferation and mature-phenotype defining genes. The broad goal is to mechanistically delineate key pathways regulating functional β-cell mass that can be harnessed to promote human β-cell proliferation with preserved function, through genetic loss- and gain-of- function studies using in vivo mouse models and ex vivo mouse and human islets and human iPSCs. We will specifically 1. To test if enhancing Yap activity in adult β-cells in vivo is sufficient for β-cell proliferation and maintenance of mature function via co-activation of Tead1, in GOF studies (overexpressing constitutively nuclear phospho-mutant YapS112A specifically in adult mouse β-cells using a Tet-On system) in inducing proliferation and expansion of β-cells under high fat diet induced insulin resistant stat, identifying direct targets of Tead1 in β-cells under basal and proliferating states and delineate Tead1 dependent and independent Yap targets in β-cells. 2. Test if mammalian Hippo-Tead1 pathway is required for human β- cell differentiation and proliferation by assessing if Yap/Taz-Tead1 regulates iPSC differentiation into pancreatic progenitors and β-cells and identify the molecular targets of Tead1 in this process. We will also test if modulation of Tead1 activity improves β-cell function and proliferation in isolated human islets and if this regulatory role is impaired in diabetes. Collectively the proposed studies will critically address how the Hippo- Tead1 pathway regulates β-cell function and proliferation in human β-cells. With the significant rise in incidence of diabetes in veterans, there is an urgent need to develop novel therapies to reverse declining functional β-cell mass and successful completion of the proposed experiments will address this critical need.

糖尿病是导致退伍军人发病率和死亡率的主要原因之一。老兵 人群特别容易患糖尿病，令人震惊的是70%的退伍军人有患糖尿病的风险。25% 所有退伍军人中患有糖尿病的人，与普通人群中的老年美国人相似。一次失败 增加β细胞增殖和功能性β细胞质量，以应对来自 与肥胖和衰老相关的胰岛素抵抗是导致成人糖尿病的主要原因 退伍军人。因此，当务之急是确定调节功能性β细胞团的途径，这可能是 用于治疗β细胞衰竭和糖尿病。我们的数据表明，Tead1，一个关键的转录 哺乳动物河马途径的效应器，在小鼠和人的胰岛中强势表达，并具有非 在调节β-细胞增殖和功能中的多余作用。哺乳动物河马-Tead1途径包括 核心激酶级联，最终与Lats1和2，抑制性激酶，磷酸化辅活化子，YAP和 TAZ，阻止它们的核移位和Tead1介导的转录调节细胞的共激活 增殖和凋亡。这一提议的前提是我们的初步数据，这些数据强烈表明 在成年β细胞中，Tead1是调控增殖抑制、促进成熟功能的开关。 最近的报告发现了一些相反的结果，其中：(A)YAP-Tead1在许多β- 人类胚胎胰腺祖细胞中的细胞成熟基因，(B)YAP也被证明抑制 小鼠内分泌与人iPS细胞分化过程中成熟功能的获得 (Hipscs)，但(D)足以在体外诱导人胰岛的增殖。初步数据显示，β-CELL 特定的Tead1基因缺失会导致糖尿病和葡萄糖耐量减低。团队1-空的小岛显示减少 成熟的β细胞标志物的表达和葡萄糖的丧失刺激了胰岛素的分泌。此外，我们的数据 提示β细胞中胚胎Tead1的缺失也会导致严重的糖尿病，这表明Tead1是 内分泌前体细胞正常分化所必需的。全面检测β-细胞的调控 通过河马Tead1通路的分化、增殖和功能，我们假设Tead1调节 β-细胞的增殖和成熟功能的获得通过上下文依赖的辅助因子特异性， 增殖和成熟表型定义基因网络的转录调控。这个 广泛的目标是机械地描绘调节功能性β的关键通路-细胞团可以 被利用来促进人类β细胞的增殖，并保留功能，通过遗传损失和获得 使用体内小鼠模型和体外小鼠、人胰岛和人ipscs进行功能研究。我们会 具体地说，1.检测体内增强成人β细胞的YAP活性是否足以促进β细胞的增殖 在GOF研究中，通过共激活Tead1来维持成熟的功能(过度表达 使用Tet-On系统在成年小鼠β细胞中特异性地构建核磷酸突变体YapS112A)。 高脂饮食诱导β细胞增殖扩增诱导胰岛素抵抗状态，鉴定 在基础状态和增殖状态下的β细胞中Tead1的直接靶点并描绘Tead1依赖和 β-细胞中的独立YAP靶点。2.检测人类β是否需要哺乳动物河马-Tead1途径- 通过评估YAP/Taz-Tead1是否调节IPSC分化为 并确定Tead1在这一过程中的分子靶点。我们还将测试 如果Tead1活性的调节改善了分离的人胰岛的β细胞功能和增殖，如果这是 糖尿病患者的调节作用受损。总的来说，拟议的研究将批判性地解决河马如何- Tead1通路调节β细胞的功能和人β细胞的增殖。随着发病率的显著上升 退伍军人的糖尿病，迫切需要开发新的治疗方法来逆转功能下降的β细胞 拟议实验的大规模和成功完成将满足这一关键需求。