Defining GATA4’s Molecular Function in Gastric Cell Biology

总结 胃壁细胞（PC）通过分泌酸来消化和保护胃肠道功能， 以及合成影响其他细胞类型发育的生长因子， 产酶主细胞尽管人们对PC生物学和胃酸的定义一直很感兴趣， 自19世纪以来，PC的研究一直是一个挑战。PC功能障碍，包括酸 分泌过多或分泌不足是一系列与高社会经济地位相关的人类疾病的基础。 负担包括慢性胃炎、药物相关消化性溃疡疾病、幽门螺杆菌相关消化性溃疡 疾病和癌症。例如，消化性溃疡疾病每年影响美国400多万人 每10个人中就有1人至少经历过一次溃疡，胃癌是第三大癌症原因 全球相关死亡考虑到PC在维持健康胃中的重要作用， 全面了解调节和维持正常PC的分子程序， 分化和功能，从而PC健康和整体胃上皮细胞健康是不完整的。我们 发现转录因子GATA 4结合到调节区-增强子和启动子-的 81%的基因集被定义为在PC中唯一表达，这揭示了PC知识的差距， 暗示GATA 4是PC生物学的关键主要调节器。本提案的目的是测试 中心假设GATA 4是维持成熟胃上皮稳态所必需的， 直接控制定义PC功能的基因表达程序。目标1中的研究将定义 使用条件性小鼠模型删除PC中的GATA 4，探讨GATA 4对PC功能的作用机制 以及一套形态学和分子学的研究工具目标2中的研究，使用Gata 4条件 在我们实验室中唯一可用的敲入模型，在PC中过表达GATA 4， 将提供证据，以确定GATA 4丢失在多大程度上是PC功能障碍所必需的， 下游化生。我们还将研究GATA 4启动子高甲基化对PC的作用。 功能障碍和化生。最后，目标3中的研究将把小鼠的发现应用于人类PC生物学 使用人类胃类器官来确定PC中GATA 4功能的进化程度 保守的总的来说，我们希望我们的研究能够阐明GATA 4依赖的分子途径， 维持PC功能和健康，并且当被破坏时，引起PC功能障碍和胃病。 发现基本的细胞和分子机制，在这种情况下，这些基础正常胃 上皮细胞稳态，可以提供先决条件的知识，适用于未来的临床应用， 胃疾病，包括胃炎、消化性溃疡病、化生和癌症。

SUMMARY Gastric parietal cells (PCs) play a critical role in GI function by secreting acid for digestion and protection against infection and by synthesizing growth factors that influence the development of other cell types including zymogenic chief cells. Although there has been longstanding interest in defining PC biology and gastric acid secretion dating back to the 1800s, PCs have been challenging to study. PC dysfunction, including acid hypersecretion or hyposecretion, underlies a range of human diseases associated with a high socioeconomic burden including chronic gastritis, drug-related peptic ulcer disease, Helicobacter pylori related peptic ulcer disease, and cancer. For example, peptic ulcer disease affects more than 4 million people in the US each year with 1 in 10 persons experiencing an ulcer at least once, and gastric cancer is the third leading cause of cancer related deaths worldwide. Given the essential role for PCs in maintaining a healthy stomach, it is surprising that a comprehensive understanding of the molecular programs that regulate and maintain normal PC differentiation and function, and thereby PC health and overall gastric epithelial cell health, is incomplete. Our finding that the transcription factor GATA4 binds to the regulatory regions—enhancers and promoters—of 81% of gene set defined as being uniquely expressed in PCs sheds light on the PC knowledge gap, implicating GATA4 as a crucial principal regulator of PC biology. The goal of this proposal is to test the central hypothesis that GATA4 is required to maintain homeostasis of the mature gastric epithelium by directly controlling the gene expression program defining PC function. Studies in Aim 1 will define the mechanistic contribution of GATA4 to PC function using a conditional mouse model to delete GATA4 in PCs and a suite of morphological and molecular investigative tools. Studies in Aim 2, using a Gata4 conditional knock-in model uniquely available in our lab to overexpress GATA4 in PCs in conjunction with gastric injury, will provide evidence to determine the extent to which GATA4 loss is necessary for PC dysfunction and downstream metaplasia. We will also examine the contribution of GATA4 promoter hypermethylation to PC dysfunction and metaplasia. Finally, studies in Aim 3 will apply findings from the mouse to human PC biology using human gastric organoids to determine the extent to which GATA4 function in PCs is evolutionarily conserved. Overall, we expect our studies to elucidate GATA4-dependent molecular pathways essential to maintain PC function and health and that, when disrupted, cause PC dysfunction and gastric disease. Discoveries of fundamental cellular and molecular mechanisms, in this case those underpinning normal gastric epithelial cell homeostasis, can provide prerequisite knowledge to apply to future clinical applications for gastric diseases including gastritis, peptic ulcer disease, metaplasia, and cancer.