Cell Cycle Control Of Beta Cell Mass

描述（由申请人提供）：了解调节β细胞群的分子机制对促进β细胞再生和治疗糖尿病具有重要意义。这项资助支持的研究已经确定了β细胞复制在生长，生理扩张和再生过程中调节β细胞质量的重要性。 在过去的资助周期中，我们已经表明，细胞周期蛋白D2不仅在建立β细胞群中起着关键作用，而且在适应胰岛素抵抗中也起着关键作用。我们确定了代谢变化如何通过调节p27细胞丰度的机制来调节β细胞群。最近，我们已经表明，β细胞复制的年龄依赖性能力随着年龄的增长而下降，并受到polycomb基因的调控，该基因通过表观遗传机制控制细胞周期调节因子p16 Ink 4a的水平。在接下来的五年里，我们建议设计表观遗传策略，可以增强成年人的β细胞复制，测试再生损伤模型中β细胞复制的要求，并开发新的成像工具来可视化生长，发育和再生过程中的β细胞复制。我们建议研究：目的1、体内β细胞内Ezh 2水平升高是否能抑制p16 Ink 4a，促进β细胞复制，增强成年小鼠β细胞再生;在目标2中，通过产生和分析β细胞中缺乏Brg 1的小鼠并进行基因组-在目的3中，评估将细胞周期蛋白D2引入细胞周期蛋白D2缺失小鼠的β细胞中是否足以促进β细胞生长和再生;在目的4中，提出监测胰腺发育期间细胞周期动力学的时空模式，出生后生长和再生使用一种新的转基因小鼠系统与荧光传感器。 这些研究将使用无效小鼠突变体、β细胞特异性诱导型转基因小鼠和培养的胰岛，使用在实验室中完全实施的方法进行。该提议的主要总体优势在于，我们已经产生或获得了本文所述的所有小鼠，并评估了它们的育种性能，并进行了杂交以验证我们产生所需基因型的能力。

DESCRIPTION (provided by applicant): Understanding the molecular mechanisms that regulate beta cell mass have important ramifications for fostering beta cell regeneration and the treatment of diabetes. Studies supported by this grant have established the importance of beta cell replication in regulating beta cell mass during growth, physiological expansion and regeneration. During the past funding cycle, we have shown that cyclin D2 plays a key role not only in establishing beta cell mass but also in adapting to insulin resistance. We established how metabolic changes lead to modulation of beta cell mass by mechanisms that regulate the cellular abundance of p27. Recently, we have shown that the age-dependent capacity of beta cells to replicate declines with age and is regulated by polycomb genes that control the levels of cell cycle regulator, p16Ink4a by epigenetic mechanisms. In the next five years we propose to design epigenetic strategies that can enhance beta cell replication in adults, test the requirements of beta cell replication in injury models of regeneration and develop new imaging tools to visualize beta cell replication during growth, development and regeneration. We propose to study: Aim 1, whether increased Ezh2 levels in beta cells in vivo can inhibit p16Ink4a, promote beta cell replication and enhance beta cell regeneration in adult mice; in Aim 2, study the mechanism by which Brg1 regulates beta cell replication in vivo by generating and analyzing mice that lack Brg1 in beta cells and carry out genome-wide analysis of Brg1 targets on cell cycle regulators in beta cells; in Aim 3, assess whether introduction of cyclin D2 into beta cells of cyclin D2 null mice is sufficient for beta cell growth and regeneration; in Aim 4, propose to monitor the spatiotemporal patterns of cell-cycle dynamics during pancreas development, growth in postnatal period and regeneration using a novel transgenic mouse system with fluorescent sensors. These studies will be carried out using null mouse mutants, beta cell-specific inducible transgenic mice, and cultured islet, using methods that are fully implemented in the laboratory. A major overall strength of this proposal is that we have already generated or obtained all the mice described here as well as assessed their breeding performance, and have carried out intercrosses to verify our ability to generate desired genotypes.