Intersection of signaling pathways and transcription factors regulating islet development

糖尿病是一项巨大的卫生保健负担，对这种疾病及其相关并发症的管理费用很高。人类多能干细胞（PSC），包括胚胎干细胞（ES）和诱导多能干细胞（iPS），为人类疾病的研究和治疗提供了巨大的潜力。啮齿动物模型在理解胰腺发育和生成糖尿病模型方面也至关重要。在这里，我们建议使用这两个互补系统来研究人类胰腺的发育和功能，重点关注通过胰岛素分泌调节血糖的β细胞。虽然啮齿类动物的研究取得了巨大的进步，但人类和老鼠并不相同，重要的是要确定胰腺生物学的差异，因为这些差异可能会影响糖尿病的治疗。例如，转录因子GATA6或GATA4的杂合突变已被证明可导致人类胰腺发育不全，其中GATA6的突变是这种遗传疾病最常见的原因（约50%）。与人类表型相反，GATA6或GATA4杂合的小鼠没有胰腺表型。GATA4和GATA6的复合突变确实模拟了人类疾病，这表明在胰腺发育过程中，GATA家族成员总体上是保守的，但人类对这些基因的剂量更为敏感。在啮齿类动物模型中，视黄酸（RA）信号是胰腺发育的关键介质，也是从人类psc生成β细胞的定向分化方案所需的信号输入。RA也是已知的GATA6和GATA4表达的调节因子。我们将在小鼠和人类PSC模型系统中研究RA和GATA4/6之间的相互作用。具体来说，将使用GATA家族成员中的突变体以及两种系统中的显性负RXR构建体，评估它们对胰腺规格和内分泌细胞发育的影响及其差异。最后，我们将研究5 ' GATA6增强子的单核苷酸多态性，在初步数据中，我们证明了它调节人类PSC系统中GATA6的表达和胰腺发育。这些研究将有助于确定人类和小鼠β细胞之间的发育和功能差异，这些差异不仅有可能直接影响罕见遗传形式糖尿病的治疗，而且还揭示了具有1型和2型糖尿病管理意义的独特人类β细胞生物学。

Diabetes is an immense healthcare burden, with great costs for management of this disease and its associated complications. Human pluripotent stem cells (PSC)s, including embryonic stem (ES) cells and induced pluripotent stem (iPS) cells offer great potential for the study and treatment of human disease. Rodent models have also been critical in understanding pancreas development and generating models of diabetes. Here, we propose to use both complementary systems to study human pancreatic development and function, with a focus on the beta cell, which regulates blood glucose via insulin secretion. While rodent studies have produced tremendous advancements, human and mice are not the same and it is important to define differences in pancreas biology as these could impact the treatment of diabetes. For example, heterozygous mutations in the transcription factors GATA6 or GATA4 have been shown to cause pancreas agenesis in humans, with mutations in GATA6 being the most common cause of this genetic disease (~50%). In contrast to the human phenotype, mice heterozygous for either GATA6 or GATA4 have no pancreatic phenotype. Compound mutations of GATA4 and GATA6 do mimic the human disease suggesting an overall conservation in GATA family members in pancreas development but with humans being much more sensitive to dosage of these genes. Retinoic Acid (RA) signaling is a critical mediator of pancreas development both in rodent models and is a required signaling input in directed differentiation protocols generating beta cells from human PSCs. RA is also a known regulator of GATA6 and GATA4 expression. We will examine the interplay between RA and GATA4/6 in both the mouse and human PSC model systems. Specifically, will use mutants in GATA family members as well as dominant negative RXR constructs in both systems, assessing conservation and differences in their impact on pancreas specification and endocrine cell development. Lastly, we will study a single nucleotide polymorphism in the 5’ GATA6 enhancer, which in preliminary data we demonstrate regulates GATA6 expression and pancreas development in the human PSC system. These studies will help define the developmental and functional differences between human and mice beta cells that have the potential to directly impact the treatment of not only rare genetic forms of diabetes but also reveal unique human beta cell biology with implications in the management of both type 1 and type 2 diabetes.