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: 7587761
• 负责人: James F. Collins
• 金额: $ 0.95万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 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/7587761
• 关键词: ATP phosphohydrolase; Address; Age; Anemia; Anemia due to Chronic Disorder; Animal Model; Apical; Cells; Ceruloplasmin; Chronic Disease; Copper; Cultured Cells; 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; Play; Post-Transcriptional Regulation; Process; Proteins; Rattus; Regulation; Reporting; Research Personnel; Rodent Model; Role; Serum; Small Interfering RNA; Small Intestines; Staging; Techniques; Testing; Time; Trace Elements; Transcriptional Regulation; Vesicle; absorption; apical membrane; base; basolateral membrane; brush border membrane; deprivation; design; dietary control; divalent metal; hypocupremia; in vitro Model; in vivo; intestinal epithelium; jejunum; metal transporting protein 1; novel; postnatal; programs; response

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, includinganemia 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 ofthis proposal are i) to determine the roles that Dmti and Atpyaplay in the induction of copper transport duringiron-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 AIMi 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 ofthe intestinal epithelium, the IEC-6 cells. Oncethe transporter(s) involved in the induction of copper transport during iron-deficiency have been identified,we willperform complementary studies in in vivomodels of iron-deficiency, includingwild-type, iron-deficientrats, Belgrade (i.e. Dmti-deficient)rats and Atpya knockout mice. SpecificAIM 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, specificAIM 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 ofiron- deficiency. A detailed understandingof 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.

铁稳态的总体控制发生在近端小细胞上皮的运输步骤中。 肠道，其吸收受到精确调节以匹配体内铁的损失。重要的是，扰动 肠道铁转运与人类的几种重要疾病状态有关，包括贫血 慢性疾病和血色素沉着症。缺铁期间大鼠的肠道铜转运增强， 这可能是与膳食铜在整体的各个方面的作用相关的生理反应 体内铁稳态。有趣的是，Menkes 铜 ATP 酶 (Atpya) 在十二指肠中被强烈诱导。 不同出生后年龄缺铁大鼠的粘膜以及二价金属转运蛋白 i (Dmti)， 可以运输铁和铜。因此，本提案的总体目标是 i) 确定角色 Dmti 和 Atpya 在缺铁期间诱导铜转运，2) 破译 缺铁期间诱导 Dmti 和 Atpya 的分子机制，以及 3) 确定 铜对肠道跨上皮铁转运分子机制的影响。这将 通过利用肠道铁转运的细胞培养和啮齿动物模型来实现。具体AIMi将 检验 Dmti 和 Atpya 的诱导导致跨上皮铜增加的假设 缺铁期间出现的运输。铁和铜转运研究以及 siRNA 敲除研究将 在我们的肠上皮细胞 IEC-6 细胞体外模型中进行。一旦运输者 已确定参与缺铁期间诱导铜转运的物质，我们将进行 缺铁体内模型的补充研究，包括野生型、缺铁大鼠，贝尔格莱德 （即 Dmti 缺陷）大鼠和 Atpya 敲除小鼠。 SpecificAIM 2，将检验 Dmti 和 Atpya 在缺铁期间受到不同分子机制的调节。铁依赖性、缺铁后 将检查 Dmti 的转录调控（由 3' IRE 介导）和转录调控 将研究 Atpya 在 IEC-6 电池中的作用。最后，specificAIM 3 将检验增加铜的假设 缺铁期间的转运功能可增强肠道铁的铜依赖性 吸收。为了实现这一目标，将在分离的膜囊泡中进行铁转运研究 来自缺乏膳食铜的缺铁大鼠，以及肠细胞和铜蓝蛋白中的铁黄蛋白活性 将测定血清中的活性。总的来说，这些研究将进一步定义铜 铁状态下参与增强肠道铁吸收的依赖过程 不足。详细了解这些关系至关重要，因为肠道铁转运控制 整体体内铁稳态。此外，这项拟议的调查是新颖的，因为研究涉及 迄今为止，尚未有缺铁期间肠上皮细胞和肝铜水平增加的影响的报道。