Revealing LIM Domain Transcriptional Complexes that establish and maintain Beta Cell Mass

胰岛含有维持葡萄糖稳态所需的胰岛素分泌β细胞。β细胞活性或存活的功能障碍导致糖尿病，这是一种影响数百万美国人的疾病，预计人数将大大增加。这造成了巨大的经济和医疗负担。改善糖尿病结局的未来策略将包括基于细胞的疗法，其中产生功能性β细胞以补充糖尿病进展期间丢失的那些细胞。成功将需要增加我们对在发育期间和成人中分别建立和维持β细胞所需的复杂转录程序的理解。 我的实验室和其他实验室先前证明了Islet-1转录因子对胰岛细胞的增殖和分化是重要的。 发展和功能。此外，在β细胞发育的晚期阶段期间的Islet-1活性需要相互作用的转录辅助调节因子Ldb 1。然而，很少有人知道的比较靶基因和这些因素所控制的途径。Ldb 1介导的复合物的复杂性也似乎大于简单地通过胰岛-1。例如，我们最近发表的数据表明，Ldb 1/Islet-1复合物非常大，还含有SSBP 3，这是Ldb 1复合物体外活性和稳定性所需的共调节因子。这表明SSBP 3是β细胞发育和功能的新参与者。三个互补的目的将定义Ldb 1复合物在胰岛发育和成年β细胞中的比较作用。目的1将利用条件性Ldb 1基因敲除模型来测试胰腺内分泌祖细胞及其他细胞的功能。我们将研究Ldb 1如何影响胰腺标志物的表达，细胞增殖和存活，内分泌细胞的特性和胰岛功能。目标2将采用全基因组的下一代测序方法来评估内分泌祖细胞中由Ldb 1控制的基因。结果将与胰岛-1以及Pdx 1和Ngn 3进行比较，这是胰岛发育中的两个关键因素。目的3将检查新的胰腺调节因子SSBP 3在胰岛发育期间和成人β细胞功能中的体内功能，与已知的Ldb 1和Islet-1作用相比。该提议将检验我们的中心假设，即在整个胰腺器官发生和成人β细胞功能中需要多个Ldb 1复合物。我广泛 研究转录因子复合物的经验和我们现成的体外和体内试剂，使我的实验室特别适合执行这些目标。该提案报告的结果将有助于开发新的分子靶点和基于细胞的治疗方法来对抗糖尿病。

Pancreatic islets of Langerhans contain insulin-secreting β-cells required for maintaining glucose homeostasis. Dysfunction in β-cell activity or survival results in diabetes mellitus, a disease affecting millions of Americans with numbers expected to greatly increase. This is creating an enormous economic and health care burden. A future strategy for improving diabetic outcomes will include cell-based therapies wherein functional β-cells are generated to replenish those lost during diabetes progression. Success will require increasing our understanding of the complex transcriptional programs required for establishing and maintaining β-cells during development and in adults, respectively. My lab and others previously demonstrated that the Islet-1 transcription factor is important for islet cell development and function. Furthermore, Islet-1 activity during late phases of β-cell development requires the interacting transcriptional co-regulator, Ldb1. However, little is known of the comparative target genes and pathways governed by these factors. The complexity of Ldb1-mediated complexes also appears greater than simply through Islet-1. For example, our recently published data suggests that Ldb1/Islet-1 complexes are very large, also containing SSBP3, a co-regulator required for Ldb1 complex activity and stability in vitro. This suggests that SSBP3 is a new player in β-cell development and function. Three complementary Aims will define comparative roles of Ldb1 complexes during islet development, and in adult β-cells. Aim 1 will utilize conditional Ldb1 knockout models to test function in pancreatic endocrine progenitor cells and beyond. We will examine how Ldb1 impacts pancreas marker expression, cell proliferation and survival, endocrine cell identity, and islet function. Aim 2 will employ genome-wide next generation sequencing approaches to assess genes controlled by Ldb1 in endocrine progenitors. Results will be compared to Islet-1, as well as Pdx1 and Ngn3, two critical factors in developing islets. Aim 3 will examine the in vivo function of the novel pancreas regulator, SSBP3, during islet development and in adult β-cell function, as compared with known Ldb1 and Islet-1 roles. This proposal will test our central hypothesis that multiple Ldb1 complexes are required throughout pancreatic organogenesis and in adult β-cell function. My extensive experience studying transcription factor complexes and our readily available in vitro and in vivo reagents, make my lab uniquely suited to executing these Aims. Results reported from this proposal will benefit efforts in developing new molecular targets and cell-based therapies to combat diabetes.