维生素 D（钙化醇）代谢
中文名称
通路描述
维生素 D3（VD3，胆钙化醇）是一种类固醇激素，主要参与调节肠道钙吸收和骨代谢。它来自饮食，并在皮肤中通过 7-脱氢胆固醇的光解产生，释放入血液循环。极少数食物（如鱼类、暴露在阳光下的蘑菇和肝油）是维生素 D 的天然来源。世界上少数国家通过人工强化少数食物来补充维生素 D。维生素 D 的代谢产物与血浆蛋白维生素 D 结合蛋白（GC）结合在循环中（参见 Delanghe 等 2015 年，Chun 2012 年）。维生素 D 经过两次后续羟基化形成维生素的活性形式，即 1,25-二羟基维生素 D（1,25(OH)2D）。第一次羟基化发生在肝脏，随后转运到肾脏进行第二次羟基化。1,25(OH)2D 通过与核维生素 D 受体（Neme 等 2017 年）结合发挥作用，据估计有 2000 多个基因直接或间接受其调节，这些基因涉及钙稳态、免疫反应、细胞生长、分化和凋亡（Hossein-nezhad 等 2013 年，Hossein-nezhad 和 Holick 2013 年）。1,25(OH)2D 的失活是通过 C23/C24 氧化催化，由细胞色素 CYP24A1 酶介导（Christakos 等 2016 年）。
英文描述
Vitamin D (calciferol) metabolism Vitamin D3 (VD3, cholecalciferol) is a steroid hormone that principally plays roles in regulating intestinal calcium absorption and in bone metabolism. It is obtained from the diet and produced in the skin by photolysis of 7-dehydrocholesterol and released into the bloodstream. Very few foods (eg. oily fish, mushrooms exposed to sunlight and cod liver oil) are natural sources of vitamin D. A small number of countries in the world artificially fortify a few foods with vitamin D. The metabolites of vitamin D are carried in the circulation bound to a plasma protein called vitamin D binding protein (GC) (for review see Delanghe et al. 2015, Chun 2012). Vitamin D undergoes two subsequent hydroxylations to form the active form of the vitamin, 1-alpha, 25-dihydroxyvitamin D (1,25(OH)2D). The first hydroxylation takes place in the liver followed by subsequent transport to the kidney where the second hydroxylation takes place. 1,25(OH)2D acts by binding to nuclear vitamin D receptors (Neme et al. 2017) and it has been estimated that upwards of 2000 genes are directly or indirectly regulated which are involved in calcium homeostasis, immune responses, cellular growth, differentiation and apoptosis (Hossein-nezhad et al. 2013, Hossein-nezhad & Holick 2013). Inactivation of 1,25(OH)2D occurs via C23/C24 oxidation catalysed by cytochrome CYP24A1 enzyme (Christakos et al. 2016).
所含基因
13 个基因