Function of Nkx homeobox genes in enteroendocrine cell differentiation

Nkx同源盒基因在肠内分泌细胞分化中的功能

• 批准号: 7678231
• 负责人: Tracy R. Ediger
• 金额: $ 5.72万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7678231
• 关键词: Acids; Antral; Biliary; Cell Count; Cell Differentiation process; Cell Lineage; Cells; Childhood; Complex; D Cells; Development; Diffuse; Digestion; Disease; Endocrine; Endocrine Glands; Engineering; Enteroendocrine Cell; Epithelial; Epithelium; Family; G Cells; Gastric Emptying; Gastrins; Gastroenterology; Genes; Genetic; Growth; Homeobox Genes; Homeodomain Proteins; Homologous Gene; Immunohistochemistry; In Situ Hybridization; Individual; Islets of Langerhans; Joints; Knockout Mice; Laboratories; Lead; Light; Link; Malignant Neoplasms; Messenger RNA; Methods; Molecular; Mus; Neuraxis; Pancreas; Pathway interactions; Phenotype; Physiological; Play; Production; Property; Proteins; RNA; Research; Research Personnel; Reverse Transcriptase Polymerase Chain Reaction; Role; Siblings; Signal Pathway; Signal Transduction; Somatostatin; Specific qualifier value; Stomach; Tamoxifen; Techniques; Testing; To specify; Tracer; Training; Work; career; cell motility; cell type; gastrointestinal epithelium; gut endocrine cell; homeodomain; homologous recombination; member; peptide hormone; public health relevance; recombinase; repaired; transcription factor

DESCRIPTION (provided by applicant): The diffuse endocrine cells of the gut epithelium comprise the largest endocrine organ in the body and serve vital physiologic functions such as gastric emptying and motility, pancreatic and biliary secretion, and growth and repair of gut epithelium. Gastrin, a peptide hormone secreted by G cells of the antral stomach, induces acid secretion and is a key determinant of stomach pH. Little is known about gut endocrine differentiation, particularly in the stomach, although transcriptional and signaling pathways are beginning to come in focus. The homeodomain protein Nkx6.3 controls terminal differentiation of G cells as well as somatostatin-producing D cells in the stomach antrum; gastrin and somatostatin levels are respectively elevated and reduced in Nkx6.3-null mice. Although the close homolog Nkx6.2 overlaps in expression with Nkx6.3, a function for Nkx6.2 has not been established in the stomach. The aims of this proposal are to characterize the individual and joint functions of Nxk6.2 and Nkx6.3 in gastric endocrine cell differentiation and to define the lineage pathway through which Nkx6.3 specifies G cells. A central hypothesis is that G and D cells differentiate from a common precursor and that alternative cell fates in this endocrine lineage are determined by the amount of Nkx6.3, with high levels promoting G-cell differentiation. I will also examine if Nkx6.2 has similar endocrine cell-specifying properties and might compensate for Nkx6.3 when necessary. Accomplishment of these aims will require a breadth of techniques, including RNA in situ hybridization, immunohistochemistry, quantitative RT-PCR, and creation and analysis of a targeted mouse line expressing tamoxifen-inducible Cre recombinase from the endogenous Nkx6.3 locus. Thus, the proposed studies will not only shed light on molecular mechanisms of gastric endocrine cell specification but also expose me to a range of new experimental approaches and laboratory methods. Taken together, these studies will help define the differentiation pathways for gastric epithelial endocrine cells and extend my training for a research career in academic pediatric gastroenterology. PUBLIC HEALTH RELEVANCE: Cell lineage specification and differentiation occur through complex transcription factor cascades, and some gut transcription factors are linked to cancer and other disease; likewise, dysregulation of gut endocrine cells may lead to disorders of acid secretion, motility or digestion. Nkx6.3 seems to act in the final specification steps for G cells, which signal acid production in the stomach. This work will trace the pathway through which Nkx6.3 specifies G cells and also determine if the sibling factor Nkx6.2 has similar functions and/or compensate for absence of Nkx6.3.

描述（由申请人提供）：肠上皮的弥漫性内分泌细胞构成体内最大的内分泌器官，并发挥重要的生理功能，例如胃排空和蠕动、胰腺和胆汁分泌以及肠上皮的生长和修复。胃泌素是胃窦 G 细胞分泌的一种肽激素，可诱导胃酸分泌，是胃 pH 值的关键决定因素。尽管转录和信号传导途径开始成为人们关注的焦点，但人们对肠道内分泌分化（尤其是胃的内分泌分化）知之甚少。同源结构域蛋白 Nkx6.3 控制胃窦中 G 细胞以及产生生长抑素的 D 细胞的终末分化； Nkx6.3缺失小鼠中胃泌素和生长抑素水平分别升高和降低。尽管密切同源的Nkx6.2在表达上与Nkx6.3重叠，但Nkx6.2的功能尚未在胃中建立。该提案的目的是表征 Nxk6.2 和 Nkx6.3 在胃内分泌细胞分化中的个体和联合功能，并定义 Nkx6.3 指定 G 细胞的谱系途径。一个中心假设是，G 细胞和 D 细胞由共同的前体细胞分化而来，并且该内分泌谱系中的替代细胞命运由 Nkx6.3 的量决定，高水平的 Nkx6.3 会促进 G 细胞分化。我还将检查 Nkx6.2 是否具有类似的内分泌细胞特异性特性，并在必要时可能补偿 Nkx6.3。实现这些目标需要广泛的技术，包括 RNA 原位杂交、免疫组织化学、定量 RT-PCR，以及从内源性 Nkx6.3 基因座表达他莫昔芬诱导型 Cre 重组酶的靶向小鼠系的创建和分析。因此，拟议的研究不仅将揭示胃内分泌细胞规范的分子机制，而且使我接触到一系列新的实验方法和实验室方法。总而言之，这些研究将有助于确定胃上皮内分泌细胞的分化途径，并扩展我在学术儿科胃肠病学研究生涯中的培训。公共卫生相关性：细胞谱系规范和分化是通过复杂的转录因子级联发生的，一些肠道转录因子与癌症和其他疾病有关；同样，肠道内分泌细胞失调可能导致胃酸分泌、蠕动或消化紊乱。 Nkx6.3 似乎在 G 细胞的最终规范步骤中发挥作用，G 细胞发出胃酸产生的信号。这项工作将追踪 Nkx6.3 指定 G 细胞的途径，并确定兄弟因子 Nkx6.2 是否具有类似的功能和/或补偿 Nkx6.3 的缺失。