Mechanistic insights into copper metabolism

说明（申请人提供）：铜是维持生命的重要金属离子。铜代谢中的饮食和遗传疾病以及与铜相关的退行性疾病提供了惊人的证据，表明最佳铜代谢是一个关键的生物过程。铜的吸收和分布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仍有很大的空白。特别是，含铜酶如铁氧化酶、超氧化物歧化酶3、赖氨酸氧化酶、酪氨酸酶和多巴胺β -羟化酶如何在分泌途径上组装铜辅助因子尚不清楚。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、癌症和神经疾病。一项成功鉴定参与铜利用的新基因的尝试表明，在真核生物中保守的细胞内钾质子反转运蛋白是铜代谢的关键分子因子。几项研究表明，钾转运到细胞分泌途径的管腔，促进铜掺入铁氧化酶。这一令人兴奋的研究进展为更好地理解功能性铁氧化酶和其他金属蛋白的生物合成机制开辟了新的途径。使用纯化的氧化铁酶、哺乳动物细胞和小鼠模型的多学科方法将被用来追求以下具体目标：(1)使用一种缺失分泌途径钾转运蛋白的小鼠品系来表征钾在铜和铁代谢中的作用；(2)获得氧化铁酶钾催化铜金属化的机理；(3)明确钾转运体的作用模式和金属响应调控；(4)测定饲粮中钾对铜、铁吸收和分布的影响。本研究具有重要的创新意义，因为它(1)描述了一个参与重要金属离子、铜、铁和钾代谢的新分子因子；(2)发现细胞内主要阳离子钾的新功能；(3)对……有了更好的认识

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.