Molecular Mechanisms of Intestinal Metal Ion Transport During Iron-Deficiency

缺铁期间肠道金属离子转运的分子机制

• 批准号: 7636746
• 负责人: James F. Collins
• 金额: $ 26.85万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7636746
• 关键词: ATP phosphohydrolase; Address; Age; Anemia; Anemia due to Chronic Disorder; Animal Model; Apical; Cell Culture Techniques; Cells; Ceruloplasmin; Copper; Data; Development; Dietary Copper; Dietary Iron; Disease; Duodenum; Enterocytes; Epithelial; Epithelial Cells; Epithelium; Genes; Genetic; Goals; Hemochromatosis; Homeostasis; Human; Human Pathology; In Transferrin; In Vitro; Intestinal Absorption; Intestines; Investigation; Ion Transport; Ions; Iron; Knockout Mice; Learning; Link; Literature; Liver; Malnutrition; Mediating; Membrane; Menkes Kinky Hair Syndrome; Metals; Modeling; Molecular; Mucous Membrane; Mutation; Patients; Physiological; Physiological Processes; Play; Post-Transcriptional Regulation; Process; Proteins; Rattus; Regulation; Reporting; Rodent Model; Role; SLC11A2 gene; Serum; Small Interfering RNA; Small Intestines; Staging; Suggestion; Techniques; Testing; Trace Elements; Transcriptional Regulation; Vesicle; absorption; apical membrane; base; basolateral membrane; brush border membrane; deprivation; design; divalent metal; hypocupremia; in vitro Model; in vivo; in vivo Model; intestinal epithelium; jejunum; metal transporting protein 1; novel; postnatal; response

DESCRIPTION (provided by applicant): The overall control of iron homeostasis occurs at the transport step in the epithelium of the proximal small bowel, where absorption is precisely regulated to match body iron losses. Importantly, perturbations in intestinal iron transport are associated with several important disease states in humans, including anemia of chronic disease and hemochromatosis. Intestinal copper transport is enhanced in rats during iron-deficiency, and this is likely a physiological response related to the role of dietary copper in various aspects of overall body iron homeostasis. Interestingly, the Menkes copper ATPase (Atpya) is strongly induced in the duodenal mucosa of iron-deprived rats at different postnatal ages along with Divalent Metal Transporter i (Dmti), which can transport iron and copper. Thus, the overall goals of this proposal are i) to determine the roles that Dmti and Atpya play in the induction of copper transport during iron-deprivation, 2) to decipher the molecular mechanisms of induction of Dmti and Atpya during iron-deprivation and 3) to determine the effect that copper has on molecular mechanisms of trans-epithelial iron transport in the intestine. This will be accomplished by utilizing cell culture and rodent models of intestinal iron transport. Specific AIM i will test the hypothesis that induction of Dmti and Atpya is responsible for increased transepithelial copper transport seen during iron-deprivation. Iron and copper transport studies and siRNA knockdowns will be performed in our in vitro model of the intestinal epithelium, the IEC-6 cells. Once the transporter(s) involved in the induction of copper transport during iron-deficiency have been identified, we will perform complementary studies in in vivo models of iron-deficiency, including wild-type, iron-deficient rats, Belgrade (i.e. Dmti-deficient) rats and Atpya knockout mice. Specific AIM 2, will test the hypothesis that Dmti and Atpya are regulated by distinct molecular mechanisms during iron-deficiency. Iron-dependent, post- transcriptional regulation of Dmti will be examined (mediated by the 3' IRE) and transcriptional regulation of Atpya in IEC-6 cells will be studied. Finally, specific AIM 3 will test the hypothesis that increased copper transport during iron deficiency functions to enhance copper-dependent aspects of intestinal iron absorption. To accomplish this goal, iron transport studies will be performed in membrane vesicles isolated from iron-deficient rats deprived of dietary copper, and hephaestin activity in enterocytes and ceruloplasmin activity in serum will be determined. Overall, these studies will allow further definition of the copper- dependent processes that are involved in enhancing intestinal iron absorption during states of iron- deficiency. A detailed understanding of these relationships is critical, as intestinal iron transport controls overall body iron homeostasis. Moreover, this proposed investigation is novel, as studies addressing the impact of increased enterocyte and liver copper levels during iron-deficiency have not been reported to date.

描述（由申请人提供）：铁体内平衡的总体控制发生在近端小肠上皮的运输步骤上，该步骤的吸收受到精确调节以匹配人体铁损失。重要的是，肠道铁运输的扰动与人类的几种重要疾病状态有关，包括慢性疾病和血色素沉着症的贫血。在铁缺乏期间，大鼠的肠道铜运输增强了，这可能是与饮食铜在整体人体铁稳态各个方面的作用有关的生理反应。有趣的是，Menkes铜ATPase（Atpya）在不同后年龄的铁剥落大鼠的十二指肠粘膜以及二价金属转运蛋白I（DMTI）中被强烈诱导，该大鼠可以运输铁和铜。 Thus, the overall goals of this proposal are i) to determine the roles that Dmti and Atpya play in the induction of copper transport during iron-deprivation, 2) to decipher the molecular mechanisms of induction of Dmti and Atpya during iron-deprivation and 3) to determine the effect that copper has on molecular mechanisms of trans-epithelial iron transport in the intestine.这将通过利用细胞培养和肠道铁的啮齿动物模型来实现。具体目的我将检验以下假设：DMTI和ATPYA的诱导是导致铁剥离过程中看到的旋转铜转运的增加。铁和铜转运研究以及siRNA敲低将在我们的肠上皮体外模型，即IEC-6细胞中进行。一旦确定了在铁缺乏期间涉及铜转运的转运蛋白，我们将对铁缺陷的体内模型进行互补研究，包括野生型，缺乏铁缺乏的大鼠，贝尔格莱德，贝尔格莱（I.E. DMTI缺乏症）大鼠和Atpya淘汰小鼠。具体目标2将检验以下假设：DMTI和ATPYA在铁缺陷期间受到不同分子机制的调节。将研究DMTI的铁依赖性，转录后调节（由3'ire介导），并研究IEC-6细胞中ATPYA的转录调控。最后，特定的目标3将检验以下假设：在铁缺乏功能过程中增加铜转运以增强肠道吸收的铜依赖性方面。为了实现这一目标，将在从缺乏饮食铜的铁缺陷的大鼠中分离出的膜囊泡中进行铁运输研究，并确定肠肠细胞中的hephaestin活性和血清中的Ceruloplasmin活性。总体而言，这些研究将允许进一​​步定义铜依赖性过程，这些过程在铁缺乏状态下增强肠道吸收。对这些关系的详细理解至关重要，因为肠铁运输控制着整体人体铁稳态。此外，这项拟议的研究是新颖的，因为迄今尚未报道涉及肠肠细胞和肝脏铜水平增加的影响的研究。