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

朗格汉斯人的胰岛含有分泌胰岛素的β细胞，这是维持血糖稳态所必需的。β细胞活动或存活功能障碍会导致糖尿病，这是一种影响数以百万计的美国人的疾病，预计人数将大幅增加。这造成了巨大的经济和医疗负担。未来改善糖尿病预后的策略将包括基于细胞的治疗，在这种治疗中，产生功能性β细胞来补充糖尿病进展过程中丢失的细胞。成功将需要增加我们对复杂转录程序的理解，这些程序分别在发育期间和成人中建立和维持β细胞。我的实验室和其他人以前证明了胰岛-1转录因子对胰岛细胞很重要 发展和功能。此外，在β细胞发育的后期阶段，胰岛-1的活动需要相互作用的转录共调控因子LDB1。然而，对受这些因素控制的相对靶基因和途径知之甚少。LDB1介导的复合体的复杂性似乎也比简单地通过Islet-1更大。例如，我们最近发表的数据表明LDB1/Islet-1复合体非常大，也含有SSBP3，这是LDB1复合体在体外活性和稳定性所需的辅助调节因子。这表明SSBP3在β细胞的发育和功能中是一个新的参与者。三个互补的目标将确定LDB1复合体在胰岛发育过程中和成年β细胞中的比较作用。目标1将利用条件性LDB1基因敲除模型来测试胰腺内分泌祖细胞及其以外的功能。我们将研究LDB1如何影响胰腺标记物的表达、细胞增殖和存活、内分泌细胞特性和胰岛功能。AIM 2将使用全基因组下一代测序方法来评估内分泌前体细胞中由LDB1控制的基因。结果将与胰岛-1以及Pdx1和Ngn3进行比较，Pdx1和Ngn3是形成胰岛的两个关键因素。目的3将检测新的胰腺调节因子SSBP3在胰岛发育过程中的体内功能以及在成人β细胞功能中的作用，并与已知的LDB1和ISLET-1的作用进行比较。这一建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LDB1复合体。我的广博 研究转录因子复合体和我们在体外和体内随时可用的试剂的经验，使我的实验室唯一适合执行这些目标。这项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疗法来对抗糖尿病。

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.