Physiological and Pathological Aspects of Intestinal Vitamin B2 Absorption

肠道维生素 B2 吸收的生理和病理方面

• 批准号: 9215519
• 负责人: HAMID M SAID
• 金额: --
• 依托单位: VETERANS HEALTH ADMINISTRATION
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9215519
• 关键词: Acyl CoA Dehydrogenases; Affect; Alcoholism; Alcohols; Anti-Inflammatory Agents; Anti-inflammatory; Antioxidants; Apical; Biological; Carbohydrates; Cells; Cellular biology; Chronic; Clinical; Colon; Disease; Docking; Enterocytes; Epigenetic Process; Epithelial Cells; Event; Exposure to; Fazio-Londe Syndrome; Folic Acid; Functional disorder; Funding; Gene Silencing; Genes; Genetic Transcription; Grant; Health; Homeostasis; Homology Modeling; Human; In Vitro; Inborn Genetic Diseases; Infection; Inflammatory; Inflammatory Bowel Diseases; Injury; Intestinal Absorption; Intestines; Investigation; Ischemia; Knockout Mice; Laboratories; Lead; Ligands; Lipids; Maintenance; Mammals; Mediating; Metabolic; Metabolism; MicroRNAs; Micronutrients; Molecular; Mutation; Oxidation-Reduction; Pathologic; Patients; Physiological; Physiology; Play; Post-Transcriptional Regulation; Process; Property; Proteins; Publishing; Regulation; Riboflavin; Role; Salmonella enterica; Salmonella infections; Serotyping; Small Interfering RNA; Small Intestines; Source; Testing; Tissues; Vitamin B6; Vitamins; Work; absorption; acyl-CoA dehydrogenase; alcohol effect; alcohol exposure; amino acid metabolism; base; cytokine; design; enteric pathogen; feeding; immune function; in vivo; intestinal homeostasis; mouse model; negative affect; novel; public health relevance; uptake

 DESCRIPTION (provided by applicant): The long-term objectives of this renewal application continue to focus on investigating the cell/molecular physiology and pathophysiology of the intestinal vitamin B2 (riboflavin; RF) uptake process and of the factors that affect and interfere with the event. RF is essential for normal human health due to the key roles it plays in biological oxidation-reduction reactions involving lipid, carbohydrate and amino acid metabolism, and in the conversion of vitamin B6 and folate into their active forms. Recent findings have uncovered additional roles for RF in normal immune function, as an anti-inflammatory and anti-oxidant agent, and in the maintenance of normal intestinal homeostasis. Humans (mammals) cannot synthesize RF, and thus, must obtain the vitamin from exogenous sources via intestinal absorption. Studies from our laboratory and others have characterized different aspects of intestinal RF absorption and shown the process is specific and carrier-mediated; also all the three recently cloned RFVTs (RFVT-1, -2 & -3; products of the SLC52A1, SLC52A2 & SLC52A3 genes, respectively) are expressed in the intestine. In studies performed during the current funding period, we used an in vitro gene-silencing (siRNA) approach to show that the apically expressed RFVT-3 plays a major role in intestinal RF uptake. In new preliminary studies aimed at establishing the role of RFVT-3 in intestinal RF absorption in native intestine in vivo, we generated a conditional (intestinal-specific) SLC52A3 knockout (KO) mouse model and plan to use it to confirm and extend our in vitro findings. In other new preliminary studies, we have identified (via homology modeling/ligand docking analyses) putative structural features in the RFVT-3 protein that may be important for its function, obtained evidence implicating microRNAs (miRNAs) in post-transcriptional regulation of intestinal RF uptake, and have identified several potential interactig partners with RFVT-3 in intestinal epithelial cells. We also obtained evidence showing that infection of intestinal epithelial cells with S. Typhimurium, and exposure to pro-inflammatory cytokines and to bacterial LPS significantly lead to inhibition in intestinal RF uptake. Finally, w obtained new preliminary evidence suggesting possible involvement of epigenetic mechanism(s) in the inhibitory effect of chronic alcohol feeding on intestinal/colonic RF uptake that we observed during the current funding period. Based on our published studies and new preliminary findings, our working hypotheses in this proposal are that: 1) the RFVT-3 plays an important role in RF absorption in native intestine in vivo; that the transporter is post-transcriptionally regulated by microRNA; and that it has interacting partner(s) that may influence its physiology/cell biology; 2) Salmonella infection, and exposure to pro-inflammatory cytokines and to bacterial LPS inhibits intestinal RF uptake; and 3) the inhibitory effect of chronic alcohol exposure on SLC52A3 transcription in the intestine is mediated, at least in part, via epigenetic/molecular mechanism(s). Three specific aims are proposed to test these hypotheses and will utilize state-of-the-art in vivo and in vitro physiological, cellular, and molecular approaches. Results of these studies should continue to provide novel and valuable information regarding the cell/molecular physiology and pathophysiology of intestinal RF uptake and of external factors that affect and interfere with the process. This should ultimately assist us in th designing of effective strategies to optimize RF body homeostasis, especially in conditions associated with RF deficiency and sub-optimal levels.

 描述（由申请人提供）： 该更新应用的长期目标继续侧重于研究肠道维生素 B2（核黄素；RF）摄取过程的细胞/分子生理学和病理生理学，以及影响和干扰 RF 对正常事件至关重要的因素。 RF 在涉及脂质、碳水化合物和氨基酸代谢的生物氧化还原反应以及维生素 B6 和叶酸转化为其活性形式方面发挥着关键作用，因此对人类健康具有重要作用。最近的研究发现，RF 还具有其他作用。在正常的免疫功能中，作为抗炎剂和抗氧化剂，以及在维持正常的肠道稳态中，人类（哺乳动物）不能合成 RF，因此，必须通过我们的肠道吸收从外源获取维生素。实验室和其他人已经表征了肠道 RF 吸收的不同方面，并表明该过程是特异性的且由载体介导；还有最近克隆的所有三个 RFVT（RFVT-1、-2 和 -3；SLC52A1 的产物） SLC52A2 和 SLC52A3 基因分别在肠道中表达，在当前资助期间进行的研究中，我们使用体外基因沉默 (siRNA) 方法表明顶部表达的 RFVT-3 在肠道 RF 中发挥重要作用。在旨在确定 RFVT-3 在体内天然肠道中肠道 RF 吸收中的作用的新初步研究中，我们生成了条件性（肠道特异性）SLC52A3。敲除（KO）小鼠模型，并计划用它来证实和扩展我们的体外研究结果。在其他新的初步研究中，我们已经（通过同源建模/配体对接分析）鉴定了 RFVT-3 蛋白中可能的假定结构特征。其功能很重要，获得的证据表明 microRNA (miRNA) 参与肠道 RF 摄取的转录后调节，并且已经确定了肠上皮细胞中与 RFVT-3 的几种潜在相互作用伙伴。我们还获得了表明感染的证据。鼠伤寒沙门氏菌对肠上皮细胞的影响，以及暴露于促炎细胞因子和细菌 LPS 显着导致肠道 RF 摄取的抑制。最后，我们获得了新的初步证据，表明表观遗传机制可能参与了抑制作用。我们在当前资助期间观察到的慢性酒精喂养对肠道/结肠 RF 吸收的影响 根据我们发表的研究和新的初步发现，我们在本提案中的工作假设是：1) RFVT-3 在 RF 中发挥重要作用。体内天然肠道吸收；转运蛋白受到 microRNA 的转录后调节；并且它具有可能影响其生理/生物细胞的相互作用伙伴；2) 沙门氏菌感染，以及接触促炎细胞因子和细菌LPS抑制肠道RF摄取；3）慢性酒精的抑制作用； 肠道中 SLC52A3 转录的暴露至少部分是通过表观遗传/分子机制介导的，提出了三个具体目标来测试这些假设，并将利用最先进的体内和体外生理学、这些研究的结果应继续提供有关肠道射频吸收的细胞/分子生理学和病理生理学以及影响和干扰该过程的外部因素的新颖且有价值的信息。设计有效的策略来优化 RF 身体稳态，特别是在 RF 缺乏和次优水平相关的情况下。