Mechanistic insights into copper metabolism

描述(申请人提供)：铜是维持生命的重要金属离子。铜代谢的饮食和遗传障碍以及与铜有关的退行性疾病提供了强有力的证据，表明最佳的铜代谢是一个关键的生物学过程。铜吸收和分布的机制一直是一个活跃的研究问题；然而，我们对铜原蛋白的生物合成的理解存在很大差距。特别是，含铜的酶，如亚铁酸铁酶、超氧化物歧化酶3、赖氨酰氧化酶、酪氨酸酶和多巴胺β-羟基酶是如何在分泌途径中组装铜辅助因子(S)的，目前还不清楚。这是一个重要的问题，因为这些酶的功能缺陷会导致严重的疾病，包括缺铁性贫血、心血管疾病、癌症和神经性疾病。对铜利用相关新基因的成功鉴定表明，真核生物中保守的细胞内钾-质子逆向转运蛋白是铜代谢的关键分子因子。一些研究表明，钾转运到细胞分泌途径的管腔中，促进了铜与氧化铁酶的结合。这一令人兴奋的研究进展开辟了新的途径，通过它可以更好地了解功能性铁氧合酶和可能还有其他金属蛋白的生物合成机制。利用纯化的铁氧酶、哺乳动物细胞和小鼠模型的多学科方法将被用来追求下列特定目标：(1)利用一个分泌途径钾转运体缺失的小鼠品系来表征钾在铜和铁的代谢中的作用；(2)对钾促进的铜金属化铁氧酶的作用有深入的了解；(3)确定钾转运体的作用模式和金属响应调控；以及(4)确定饮食中钾对铜和铁的吸收和分配的影响。这项拟议的研究具有重大意义和创新性，因为它(1)表征了一种涉及重要金属离子、铜、铁和钾的新陈代谢的新分子因子；(2)发现了钾(一种主要的细胞内阳离子)的新功能作用；(3)更深入地了解了 营养金属离子之间的相互作用；以及(4)将导致促进铜、铁和钾的吸收和分配的方法的发展。该项目的成果应该对从机制上深入了解金属代谢、金属蛋白的生物合成以及抗击各种与金属离子有关的疾病产生广泛影响，如正常生长发育缺陷、贫血以及代谢和退行性疾病。 与公共健康相关：铜是一种维持生命至关重要的矿物质，但如果放错地方或积累过多，它是有毒的。饮食中的铜水平和参与铜代谢的分子因素已被认为是治疗的靶点。该项目旨在获得对铜在体内的吸收和利用的机械性见解，以提高我们抗击各种与金属有关的人类疾病的能力，如贫血、代谢和退行性疾病以及癌症。

DESCRIPTION (provided by applicant): Copper is a vital metal ion for sustaining life. Dietary and genetic disorders in copper metabolism and copper-implicated degenerative diseases provide striking evidence that optimal copper metabolism is a critical biological process. The mechanism underlying copper uptake and distribution has been an active research question; however, there are significant gaps in our understanding of the biosynthesis of cuproproteins. In particular, it is not known how copper-containing enzymes, such as ferroxidases, superoxide dismutase 3, lysyl oxidase, tyrosinase, and dopamine beta-hydroxylase, assemble copper cofactor(s) at the secretory pathway. This is an important problem because functional defects of these enzymes lead to serious disorders, including iron-deficiency anemia, cardiovascular disorders, cancer, and neuronal diseases. A successful attempt for identification of new genes involved in copper utilization revealed that an intracellular potassium-proton antiporter conserved in eukaryotes is a critical molecular factor for copper metabolism. Several lines of study indicate that potassium transport into the lumen of the cellular secretory pathway facilitates copper incorporation into ferroxidases. This exciting research progress has opened new avenues by which the mechanisms underlying the biosynthesis of functional ferroxidases and possibly other metalloproteins are better understood. Multi-disciplinary approaches using purified ferroxidases, mammalian cells, and mouse models will be employed to pursue the following specific aims: (1) Characterize the roles for potassium in copper and iron metabolism using a mouse strain where a secretory pathway potassium transporter is deleted; (2) Gain mechanistic insights into potassium-facilitated copper metallation of ferroxidases; (3) Define the modes of action and metal-responsive regulation of the potassium transporter; and (4) Determine the effects of potassium in the diet on copper and iron absorption and distribution. This proposed research is significant and innovative in that it (1) characterizes a new molecular factor involved in the metabolism of vital metal ions, copper, iron, and potassium; (2) discovers a novel functional role for potassium, a major intracellular cation; (3) gains better insights into the interactions among nutritional metal ions; and (4) would lead to the development of methods that facilitate absorption and distribution of copper, iron, and potassium. The outcomes of this project should have broad impacts on gaining mechanistic insights into metal metabolism, biosynthesis of metalloproteins, and combating various metal ion-related disorders, such as defects in normal growth and development, anemia, and metabolic and degenerative diseases. PUBLIC HEALTH RELEVANCE: Copper is a mineral vital for sustaining life, yet it is toxic when misplaced or accumulated in excess. Copper levels in the diet and molecular factors involved in copper metabolism have been proposed as a therapeutic target. This project aims to gain mechanistic insights into copper absorption and utilization in the body to enhance our ability to combat various metal-related human diseases, such as anemia, metabolic and degenerative diseases, and cancer.