Epigenomics of the regenerating and aging beta-cell

描述(申请人提供)：糖尿病是一种终生慢性疾病，2007年全球估计有1.8亿患者。在过去的十年里，尽管肥胖和外周胰岛素抵抗是导致糖尿病前期的因素，但很明显，胰腺细胞衰竭是导致向显性糖尿病过渡的最终事件。(-细胞衰竭在这里被定义为功能丧失，即葡萄糖刺激的胰岛素分泌，以及(-细胞质量不足，要么是由于细胞凋亡增加，要么是因为未能对代谢需求做出反应而增殖)。虽然有几种药物被用来减少胰岛素抵抗和增加胰岛素分泌，但没有一种药物能解决这种问题。事实上，目前还没有人知道可以允许这种药物开发的好靶点。在人类和啮齿动物中，随着年龄的增长，(-细胞)的增殖潜力都急剧下降。这种变化背后的表观遗传事件只被部分探索过。我们假设，充分了解与(-细胞的再生能力相关的表观遗传变化可以用来使衰老的(-细胞增殖。 具体地说，我们将通过超高通量测序技术来确定激活和抑制染色质标记以及从年轻和老年小鼠分离的(-细胞)的表达谱。我们还将研究最近分裂的(-细胞进入不应期时发生的表观遗传学变化。其次，我们利用在AIM 1中获得的年轻(-细胞)的表观遗传学特征，在旨在逆转人类(-细胞的衰老表型的条件的低通量筛选中。第三，我们将评估泛素连接酶适配器PCIF1，被证明是染色质修饰物BMI1的重要调节因子，作为逆转老年人类(-细胞)表观遗传表型的靶标。 综上所述，我们将利用全基因组方法和计算生物学工具来改变我们关于表观基因组如何反映(-细胞的老化及其增殖潜力的丧失的知识。这些数据将用于两个目的：指导旨在恢复人类胰岛活力的干预措施的开发，以及评估如何操纵它们的表观基因组以促进(-细胞)复制。因此，我们的建议有可能改变未来的糖尿病研究和治疗。 公共卫生相关性：如果我们能够开发药物来刺激胰腺中的胰岛素分泌细胞--β细胞的增殖，那么I型和II型糖尿病患者的健康状况都会得到改善。同样，如果我们在移植前能够在体外扩增β细胞团，那么更多的I型糖尿病患者可以接受胰岛移植。虽然幼儿的β细胞具有很高的增殖能力，但随着年龄的增长，这种能力会急剧下降。我们假设，表观遗传变化是导致增殖能力下降的原因。因此，我们将确定年轻和老年β细胞的表观基因组，确定它们的差异，并将其作为工具来研究可以逆转人类β细胞衰老表型的治疗方法。如果成功，这种新的方法将为糖尿病创新治疗的开发带来巨大的希望。

DESCRIPTION (provided by applicant): Diabetes mellitus is a lifelong chronic disease with worldwide prevalence estimated at 180 million patients in 2007. Over the past decade, it has become clear that failure of the pancreatic (-cell is the final event causing the transition to overt diabetes, even though obesity and peripheral insulin resistance are the factors leading to pre-diabetes. (-cell failure here is defined as loss of both function, i.e. glucose stimulated insulin secretion, and inadequate (-cell mass, either by increased apoptosis or a failure to proliferate in response to metabolic demand. While several drugs are in use to reduce insulin resistance and increase insulin secretion, none exist that address (-cell expansion and regeneration. In fact, at present, no good targets are known that would allow such drug development. There is a dramatic decline in the proliferative potential of the (-cell with age, both in humans and in rodents. The epigenetic events that underlie this change have been only partially explored. We hypothesize that a full understanding of the epigenetic changes that correlate with the regenerative capacity of the (-cell can be utilized to enable aged (-cells to proliferate. Specifically, we will determine both activating and repressing chromatin marks as well as expression profiles of (-cells isolated from young and aged mice by ultra-high throughput sequencing technology. We will also investigate the epigenetic changes that occur when a recently divided (-cell enters a refractory period. Secondly, we utilize the epigenetic profile of the young (-cell obtained in AIM 1 in a low-throughput screen of conditions aimed at reversing the aged phenotype of human (-cells. Third, we will evaluate the ubiquitin ligase adaptor PCIF1, shown to be an important regulator of the chromatin modifier BMI1, as a target for reversal of the epigenetic phenotype of the aged human (-cell. In summary, we will utilize genome-wide approaches and computational biology tools to transform our knowledge of how the epigenome reflects the aging of the (-cell and its loss of proliferative potential. These data will serve two purposes: to guide the development of interventions that aim to rejuvenate human islets, and to evaluate how their epigenome can be manipulated to favor (-cell replication. Therefore, our proposal has the potential to transform diabetes research and treatment in the future. PUBLIC HEALTH RELEVANCE: Health outcomes for both type I and type II diabetics could be improved if we could develop drugs to stimulate the proliferation of the beta-cell, the insulin producing cell in the pancreas. Likewise, more type I diabetics could be treated with islet transplantation if we could expand beta-cell mass in vitro before transplantation. While beta-cells in young children have very high proliferative capacity, this declines dramatically as we age. We hypothesize that epigenetic changes are responsible for this decline in proliferative capacity. Therefore, we will determine the epigenome of both young and aged beta-cells, define their differences, and use these as a tool to investigate treatments that can reverse the aged phenotype of the human beta-cell. If successful, this novel approach holds great promise for the development of innovative treatments for diabetes.