Mechanisms of Beta Cell Failure

描述(由申请人提供)：这项工作的目标是了解胰腺细胞失败的原因，并着眼于识别可用作药物靶点的遗传、生化和细胞通路，以预防和逆转这种疾病过程。在其十年的生命中，这笔赠款支持了最初的观察，确定了由转录因子FoxO1 THA协调的动态平衡循环，将荷尔蒙和营养信号整合到基因表达程序中，以保护细胞功能 和世系稳定。上一个资金周期的信号成就表明，长期以来被认为是继发于细胞凋亡损失的？细胞衰竭，是由于？细胞分化为表达神经生成素3的内分泌前体细胞，并部分转化为其他激素产生的细胞。在提供的支持这些研究继续进行的初步数据中，他指出，缺乏FoxO1、3a和4的小鼠或分化的？细胞发生MODY，HNF4a、HNF1a和PD1调控的转录网络显著异常。对不同突变体的转录组分析提出了一种模式，在该模式中，FoxO控制分化的？细胞的代谢灵活性，并在成熟的？细胞中获得葡萄糖能力。特派在三个相互关联的目标中寻求对这项工作的持续支持。在目标1中，PI将使用遗传学、药理学和发育工具来研究？细胞去分化的可逆性和预防。为此，PI将使用一个强大的胰岛素抵抗糖尿病模型，该模型是专门为帮助这项工作而开发的。在支持Aim 2的初步数据中，PI显示，细胞内Foxo1、3a和4的三个基因敲除会损害胰岛素的分泌，导致线粒体功能障碍，损害细胞内小泡的形成和运输，减少钙信号和支链氨基酸代谢，并增加脂质氧化。PI建议测试FoxO调节细胞代谢灵活性的假设，即在葡萄糖和非葡萄糖分泌剂之间选择作为胰岛素分泌所需的线粒体ATP合成的能量来源的能力。在im 3中，FoxO缺陷的胰腺祖细胞与分化的胰腺前体细胞的比较转录组分析？细胞显示，葡萄糖摄取和代谢所需的基因在前者中受到影响，但在后者中不受影响。PI假设这个基因集在成熟的细胞中受FoxO的特异性调控，并赋予细胞葡萄糖能力，即正确感知细胞成熟所需的葡萄糖的能力。PI建议结合发育和表观遗传分析以及候选基因方法来了解FoxO控制细胞成熟的机制。

DESCRIPTION (provided by applicant): Goal of this work is to understand why pancreatic ?-cells fail with an eye toward identifying genetic, biochemical, and cellular pathways that can be exploited asdrug targets to prevent and reverse this disease process. During its ten-year life, this grant has suppoted original observations identifying a homeostatic loop orchestrated by transcription factor FoxO1 tha integrates hormonal and nutrient signals into a gene expression program to preserve ?-cell function and lineage stability. Signal achievements of the last funding cycle have been the demonstration tht ?-cell failure, long held to be secondary to loss of ?-cells to apoptosis, is due to ?-cell dediffeentiation into endocrine progenitor-like cells that express Neurogenin3, and their partial conversion into oter hormone-producing cells. In preliminary data presented to support a continuation of these studies, he PI shows that mice lacking FoxO1, 3a, and 4 in pancreatic progenitors or differentiated ?-cells devlop MODY, with striking abnormalities of the transcriptional networks regulated by Hnf4a, Hnf1a, and Pd1. Transcriptome analyses of the different mutants suggest a model in which FoxO control metabolic flexibility in differentiated ?-cells, and acquisition of glucose competence in maturing ?-cells. Te PI seeks continuing support for this work in three interrelated aims. In Aim 1 the PI will investigatethe reversibility and prevention of ?-cell dedifferentiation, using genetic, pharmacological, and developmental tools. To this end, the PI will use a robust model of insulin-resistant diabetes, speifically developed to aid this work. In preliminary data to support Aim 2, the PI shows that triple knockoutof Foxo1, 3a, and 4 in ?-cells impair insulin secretion, results in mitochondrial dysfunction, impaire formation and trafficking of intracellular vesicles, reduced Ca signaling and branched chain amino cid metabolism, and increased lipid oxidation. The PI proposes to test the hypothesis that FoxO regulat the ?-cell's metabolic flexibility, i.e. the ability to select between glucose and non-glucose secretagogues as energy sources for mitochondrial ATP synthesis required for insulin secretion. In im 3, comparative transcriptome analyses of FoxO-deficient pancreatic progenitors vs. differentiated ? cells reveal that genes required for glucose uptake and metabolism are affected in the former, but ot in the latter. The PI hypothesizes that this gene set is specifically regulated by FoxO in maturing ?-ells, and bestows on ?-cells glucose competence, i.e. the ability to properly sense glucose that is requied for ?-cell maturation. The PI proposes to use a combination of developmental and epigenetic analyse coupled with candidate gene approaches to understand the mechanism by which FoxO control ?-cell maturation.