The molecular mechanisms of intestinal homeostasis.

肠道稳态的分子机制。

• 批准号: 8989986
• 负责人: RHEINALLT MELFYN JONES
• 金额: $ 33.93万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-20 至 2017-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8989986
• 关键词: Address; Adult; Bacteria; Biochemical; Biology; Cell Proliferation; Cells; Chemical Exposure; Cultured Cells; Cysteine; Data; Development; Disease; Drosophila genus; Employee Strikes; Enterocytes; Epithelial; Epithelial Cells; Event; Foundations; Generations; Genetic; Germ-Free; Goals; Healed; Health; Helper-Inducer T-Lymphocyte; Homeostasis; Hospitalization; Hydrogen Peroxide; Immune System Diseases; Injury; Intestinal Diseases; Intestines; Investigation; Knock-out; Knockout Mice; Knowledge; Lactobacillus; Mammals; Mediating; Methods; Mission; Modeling; Molecular; Morbidity - disease rate; Mus; NADPH Oxidase; Natural regeneration; Nox enzyme; Outcome; Physiological; Physiology; Prevention; Preventive Intervention; Probiotics; Proteins; Public Health; Radiation; Reactive Oxygen Species; Recovery; Regulator Genes; Reporting; Research; Role; Signal Transduction; Signaling Molecule; Source; Stem cells; Testing; Therapeutic; Therapeutic Intervention; Transducers; United States National Institutes of Health; Work; Wound Healing; base; cell type; commensal microbes; developmental disease; fly; gastrointestinal epithelium; genetic regulatory protein; healing; innovation; intestinal epithelium; intestinal homeostasis; member; microbial; microbiota; mortality; mouse model; novel therapeutics; oxidation; pathogen; response; sensor; therapy development; wound

DESCRIPTION (provided by applicant): There is a critical gap in our knowledge regarding the molecular mechanisms that control signaling events during intestinal homeostasis. This gap represents a barrier to scientific progress because, until it is addressed, an explanation for diseases resulting from developmental disorders in the gut will continue to be beyond our understanding. Furthermore, this gap in the knowledge hinders progress in the development of therapies to promote recovery of the intestine following injury or damage. Our long-term goal is to identify molecular mechanisms involved in epithelial homeostasis. The objective of this proposal is to identify roles for physiological ROS generation from gut- specific NADPH oxidases (Nox enzymes) in normal gut development. Based on our preliminary data, our central hypothesis is that ROS generated by Nox1 in the intestinal epithelia functions to stimulate host gene regulatory events within the intestinal stem cell (ISC) microenvironment. In addition, we have discovered that colonization of the metazoan gut with specific strains of symbiotic bacteria induces the generation of ROS within enterocytes. Thus, we also hypothesize that contact of specific members of the microbiota (and candidate probiotic agents) with intestinal cells induces NADPH oxidases to generate ROS which then act as transducers of bacterial signals into host gene regulatory events that influence homeostasis in the metazoan gut. The rationale for this hypothesis is based on established reports that ROS, especially H2O2 function as signaling molecules to modulate protein activity through the oxidation of sensor cysteine residues within regulatory proteins. In our preliminary data, we show that both intestinal-specific Nox1- null mice, and Drosophila with diminished Nox1 levels have altered intestinal physiology. Importantly, we also show that lactobacilli, which are commonly employed as candidate probiotic agents, are potent inducers of Nox1 cellular ROS generation in intestinal epithelial cells, and are potent inducers of cell proliferation by a Nox1-dependent mechanism. Based on these compelling preliminary data generated by our research group, the central hypothesis will be tested in three specific aims: 1) Identify the function of NADPH oxidases in intestinal epithelium development and homeostasis, 2) Identify the function of NADPH oxidases in intestinal epithelium regeneration following injury, and 3) Identify the influence of bacterial-induced and NADPH oxidase- dependent ROS generation on intestinal healing following injury. Our approach will employ an intestinal epithelial cell-specific deficient nox1 (B6.Nox1¿IEC) mouse, and a highly innovative genetically tractable Drosophila model whose biology can be manipulated to a far greater extent than mammalian models. Also, there is striking conservation in the molecular mechanisms of intestinal development between Drosophila and mammals. The outcomes of these investigations will have a positive impact on public health because of direct implications to idiopathic intestinal and systemic immune and developmental disorders and provides a springboard to the development of preventative interventions for these conditions.

描述（由申请人提供）：在我们的知识中，关于在肠道稳态期间控制信号传导事件的分子机制，存在关键的差距。这一差距是科学进步的障碍，因为在解决这一问题之前，对肠道发育障碍引起的疾病的解释将继续超出我们的理解。此外，这种知识上的差距阻碍了促进损伤或损害后肠道恢复的疗法的发展。我们的长期目标是确定参与上皮内环境稳定的分子机制。本提案的目的是确定正常肠道发育中肠道特异性NADPH氧化酶（Nox酶）的生理ROS生成作用。基于我们的初步数据，我们的中心假设是，肠上皮细胞中的Nox 1产生的ROS的功能，以刺激肠道干细胞（ISC）微环境内的宿主基因调控事件。此外，我们还发现，共生细菌的特定菌株在后生动物肠道的定植诱导肠上皮细胞内ROS的产生。因此，我们还假设微生物群的特定成员（和候选益生菌剂）与肠细胞的接触诱导NADPH氧化酶产生ROS，然后作为细菌信号的转换器进入宿主基因调控事件，影响后生动物肠道中的稳态。这一假设的基本原理是基于已建立的报告，即ROS，特别是H2 O2作为信号分子，通过氧化调节蛋白内的传感器半胱氨酸残基来调节蛋白质活性。在我们的初步数据中，我们表明，肠道特异性Nox 1缺失小鼠和Nox 1水平降低的果蝇都改变了肠道生理学。重要的是，我们还表明，乳酸杆菌，这是常用的候选益生菌剂，是有效的诱导剂的Nox 1细胞活性氧产生在肠上皮细胞，是有效的诱导剂的细胞增殖的Nox 1依赖性机制。基于我们的研究小组产生的这些令人信服的初步数据，中心假设将在三个具体目标中进行测试：1）鉴定NADPH氧化酶在肠上皮发育和稳态中的功能，2）鉴定NADPH氧化酶在损伤后肠上皮再生中的功能，和3）鉴定细菌诱导的和NADPH氧化酶依赖性ROS产生对损伤后肠愈合的影响。我们的方法将采用肠上皮细胞特异性缺陷型nox 1（B6.Nox1 <$IEC）小鼠和高度创新的遗传学上易于处理的果蝇模型，其生物学可以在比哺乳动物模型更大的程度上进行操纵。同时，果蝇和哺乳动物在肠道发育的分子机制上也存在着惊人的保守性。这些调查的结果将对公共卫生产生积极影响，因为它直接影响到特发性肠道和全身免疫和发育障碍，并为这些疾病的预防干预措施的发展提供了一个跳板。