Signaling in digestive epithelial development and homeostasis

消化上皮发育和稳态中的信号传导

• 批准号: 9128613
• 负责人: Ramesh A Shivdasani
• 金额: $ 36.11万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9128613
• 关键词: Address; Affect; Award; BHLH Protein; Behavior; Binding; Binding Sites; Biogenesis; Blood Platelets; Cell Cycle; Cell Differentiation process; Cell Lineage; Cells; Chromatin; Colorectal Cancer; Cues; DNA; Dependency; Development; Digestive Physiology; Disease; Elements; Engineering; Enterocytes; Epigenetic Process; Epithelial; Epithelium; Factor Analysis; Foundations; Gastrointestinal tract structure; Gene Targeting; Generations; Genes; Genetic; Genetic Enhancer Element; Genetic study; Grant; Health; Histones; Homeostasis; Hormones; Human Pathology; Inflammatory; Inflammatory Bowel Diseases; Intestinal Diseases; Intestines; Laboratories; Lateral; Light; Malignant - descriptor; Malignant Neoplasms; Methods; Molecular; Molecular Genetics; Mucinous; Mucus-Secreting Cell; Mus; Nature; Notch and Wnt Signaling Pathway; Nucleosomes; Paneth Cells; Pathway interactions; Physiological; Population; Process; Proteins; Regenerative Medicine; Regulatory Element; Role; Sampling; Secretory Cell; Signal Pathway; Signal Transduction; Small Intestines; Specimen; Stem cells; T cell factor 4; TF gene; Testing; Therapeutic; Tissues; To specify; Villus; base; chromatin immunoprecipitation; clinical application; common treatment; crypt cell; epigenome; epigenomics; genome-wide; human disease; improved; in vivo; innovation; intestinal crypt; mouse model; notch protein; novel strategies; progenitor; programs; research study; stem; stem cell biology; therapeutic target; transcription factor

DESCRIPTION (provided by applicant): Intestinal disorders such as inflammatory bowel disease (IBD) and cancer frequently reflect dysregulated activity of crypt stem and progenitor cells. Relationships among these cells are presently coming into focus but it remains unclear how the key cell populations regulate lineage-specific genes to choose among alternative enterocyte and secretory cell fates. Intestinal crypt homeostasis most notably requires Notch and Wnt signaling, among other pathways. The two canonical signals cooperate to promote cell replication, but whereas Wnt signaling promotes intestinal secretory cell differentiation, Notch signaling favors enterocyte differentiation at the expense of secretory cells; the basis for these differences is unknown. Notch inhibits expression of transcription factor Atoh1 (Math1), whose activity or absence seems sufficient to allocate cell lineages by the evolutionarily conserved process of lateral inhibition. Manipulation of GI signaling pathways for clinical application will require a deeper appreciation of underlying principles and mechanisms to identify therapeutic targets that will least disrupt normal digestive physiology. This proposal applies innovative methods to isolate mouse intestinal crypt progenitors and to study in fresh detail the epigenetic and transcriptional basis of cell fate decisions. In Specific Aim 1 we will identify lineage- restricted enhancer elements and genome-wide binding sites for Atoh1 in purified secretory progenitors, with the view to determine mechanisms for its potent ability to specify the full secretory lineage. We will analyze Atoh1 occupancy at cis-elements with respect to nucleosome-histone dynamics in the transition from stem cells to committed progenitors. We will define Atoh1 target genes and investigate the roles of such genes in human pathology specimens showing aberrant secretory differentiation, including IBD samples and mucinous/signet-ring colorectal cancer. To explain the multi-faceted relationship of Wnt and Notch signaling in gut epithelial progenitors, we will test the hypothesis that Atoh1 steers the Wnt-effector transcription factor Tcf4 away from cis-elements of proliferative genes and toward those of a Wnt- dependent secretory cell program. In Specific Aim 2 we propose to isolate the earliest stem-cell progeny, bipotential progenitors able to differentiate into secretory cells or enterocytes. We will study the epigenetic basis and Atoh1 dependencies for their subsequent commitment to a single fate. We will test the hypothesis that Atoh1 controls histone marks and nucleosome dynamics not only to activate secretory cis- elements but also to repress enterocyte genes. Using genetic mouse models and up-to-date approaches in epigenomic and transcription factor analysis, we propose experiments that will give clear answers and test specific predictions and hypotheses. These studies collectively address fundamental questions, explore developmental signaling and regulatory mechanisms in molecular detail in vivo, test specific and cogent hypotheses, and will contribute toward improved understanding and treatment of common GI disorders.

描述（由申请人提供）：肠道疾病（例如炎症性肠病（IBD）和癌症）经常反映出隐型茎和祖细胞的活性失调。这些细胞之间的关系目前正处于焦点，但尚不清楚关键细胞种群如何调节谱系特异性基因在替代肠球菌和分泌细胞命运中选择。肠道隐窝稳态最值得注意的是，以及其他途径以及其他途径。两个规范信号合作以促进细胞复制，但是Wnt信号传导促进肠道分泌细胞的分化，Notch信号传导偏向于肠细胞的分化，以牺牲分泌细胞为代价。这些差异的基础是未知的。 Notch抑制转录因子ATOH1（MATH1）的表达，其活性或缺失似乎足以通过进化保守的侧向抑制过程分配细胞谱系。对临床应用的GI信号传导途径的操纵将需要更深入地了解基本原理和机制，以鉴定会破坏正常消化生理学的治疗靶标。该建议采用创新方法来分离小鼠肠道隐窝祖细胞，并详细研究细胞命运决策的表观遗传和转录基础。在特定的目标1中，我们将确定纯化的分泌祖细胞中ATOH1的谱系限制增强子元素和全基因组结合位点，以确定其有能力指定完整分泌谱系的机制。我们将在从干细胞到忠实的祖细胞的过渡中分析顺式元素的ATOH1占用率。我们将定义ATOH1靶基因，并研究此类基因在人类病理标本中的作用，显示异常分泌分化，包括IBD样品和粘液/标志环结直肠癌。为了解释肠道上皮祖细胞中Wnt和Notch信号传导的多面关系，我们将测试以下假设：ATOH1引导Wnt-Peffector转录因子TCF4 TCF4从增殖基因的顺式元素和Wnt依赖的分泌细胞程序的顺式元素中。在特定的目标2中，我们建议将能够分化为分泌细胞或肠细胞的最早的双胞胎祖细胞分离出最早的干细胞后代。我们将研究表观遗传基础和ATOH1依赖性，以便其随后对单一命运的承诺。我们将检验以下假设：ATOH1控制组蛋白标记和核小体动力学不仅激活分泌元件，还可以抑制肠上皮细胞基因。使用遗传小鼠模型和表观基因组和转录因子分析中的最新方法，我们提出了实验，这些实验将提供清晰的答案并检验特定的预测和假设。这些研究共同解决了基本问题，在体内探索发育信号传导和调节机制，在体内，检验特定和可言的假设，并将有助于改善对常见GI疾病的理解和治疗。