Defining GATA4’s Molecular Function in Gastric Cell Biology

摘要 胃壁细胞(PC)通过分泌酸进行消化和保护，在胃肠道功能中起关键作用。 通过合成影响其他类型细胞发育的生长因子，包括 产酶主细胞。尽管长期以来人们对PC生物学和胃酸的定义感兴趣 分泌物可以追溯到19世纪，个人电脑的研究一直具有挑战性。PC功能障碍，包括酸中毒 高分泌或低分泌，是一系列与高度社会经济相关的人类疾病的基础。 负担包括慢性胃炎、药物相关性消化性溃疡、幽门螺杆菌相关性消化性溃疡 疾病和癌症。例如，美国每年有400多万人罹患消化性溃疡 每10个人中就有1人至少经历一次溃疡，而胃癌是第三大致癌原因 全球范围内的相关死亡。考虑到个人电脑在维持胃健康方面的重要作用，这是令人惊讶的 对调节和维持正常PC的分子程序的全面理解 分化和功能，从而PC健康和整个胃上皮细胞健康是不完整的。我们的 发现转录因子GATA4结合到的调节区-增强子和启动子- 被定义为在PC中唯一表达的81%的基因组揭示了PC知识差距， 这意味着GATA4是PC生物学的一个重要的主要调节因子。这项提案的目标是测试 中心假设GATA4是维持成熟胃上皮细胞动态平衡所必需的 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 使用条件鼠标模型删除PC中的GATA4的GATA4对PC功能的机制贡献 以及一套形态和分子研究工具。目标2中的研究，使用GATA4条件 我们实验室独一无二的敲入模型，可以在PC中过度表达GATA4，并伴随着胃损伤， 将提供证据来确定GATA4丢失在多大程度上是PC功能障碍和 下游化生。我们还将研究GATA4启动子超甲基化在PC中的作用 功能障碍和化生。最后，《目标3》中的研究将把小鼠的研究成果应用于人类个人电脑生物学 使用人胃类器官来确定GATA4在PC中的作用程度是进化的 保守的。总体而言，我们希望我们的研究能够阐明GATA4依赖的分子通路 维持PC的功能和健康，当中断时，会导致PC功能障碍和胃病。 发现了基本的细胞和分子机制，在这种情况下，那些支持正常胃的机制 上皮细胞动态平衡，可以为应用于未来的临床应用提供必要的知识 胃病包括胃炎、消化性溃疡、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.