Evidence for the activation of 1α-hydroxyvitamin D2 by 25-hydroxyvitamin D-24-hydroxylase:: Delineation of pathways involving 1α,24-dihydroxyvitamin D2 and 1α,25-dihydroxyvitamin D2
Evidence for the activation of 1α-hydroxyvitamin D2 by 25-hydroxyvitamin D-24-hydroxylase:: Delineation of pathways involving 1α,24-dihydroxyvitamin D2 and 1α,25-dihydroxyvitamin D2
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DOI：
10.1016/j.bbalip.2006.01.004
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发表时间：
2006-02-01
影响因子：
4.8
通讯作者：
Jones, G
中科院分区：
文献类型：
--
作者：
Masuda, S;Strugnell, SA;Jones, G
虽然目前的理论认为维生素D前药需要肝酶的侧链激活，但最近的数据表明羟基化也可能发生在肝外。我们使用角化细胞和重组人酶来测试25-羟基维生素D-24-羟化酶（CYP24A1）是否能够在体外激活和失活模型前药1 α -羟基维生素D （lot(OH)D-2）。经CYP24A1 （V79-CYP24A1）稳定转染的哺乳动物细胞将la(OH)D转化为一系列代谢产物，类似于在鼠瘤角质形成细胞和人类细胞系HPK1A-ras中观察到的代谢产物，证实了CYP24A1在代谢中的核心作用。1 α (OH)D的产物包括活性代谢物1 α，24-二羟维生素D-2 (1 α,24（OH)(2)D-2）和1 α，25-二羟维生素D（批号，25 (OH)2D2）；两者的形成表明存在不同的激活途径。一种新的水溶性代谢物，鉴定为26-羧基-1 α，24(OH)(2)D-2，是由CYP24A1通过连续的24-羟基化，26-羟基化和C-26进一步氧化合成的lot(OH)D-2的最终降解产物。这种酸在Cyp24a1缺失小鼠的角质形成细胞中不存在。与1 α，25(OH)(2)D-2和1 α，25(OH)(2)D-2和1 α，25(OH)(2)D-3相比，lot(OH)D和1 α，24(OH)(2)D-2的清除率较慢，这表明24羟基化代谢物在改变1 α (OH)D-2的生物活性谱中发挥了作用。我们的研究结果表明，CYP24A1可以在体外激活和灭活皮肤和其他靶细胞中的维生素D前药，为局部给药治疗银屑病等增生性疾病提供了可能。(c) 2006 Elsevier B.V.版权所有
While current dogma argues that vitamin D prodrugs require side-chain activation by liver enzymes, recent data suggest that hydroxylation may also occur extrahepatically. We used keratinocytes and recombinant human enzyme to test if the 25-hydroxyvitamin D-24-hydroxylase (CYP24A1) is capable of target cell activation and inactivation of a model prodrug, 1 alpha-hydroxyvitamin D, (lot(OH)D-2) in vitro. Mammalian cells stably transfected with CYP24A1 (V79-CYP24A1) converted la(OH)D, to a series of metabolites similar to those observed in murme keratinocytes and the human cell line HPK1A-ras, confirming the central role of CYP24A1 in metabolism. Products of 1 alpha(OH)D, included the active metabolites 1 alpha,24-dihydroxyvitamin D-2 (1 alpha,24(OH)(2)D-2) and 1 alpha,25-dihydroxyvitamin D, (lot,25 (OH)2D2); the formation of both indicating the existence of distinct activation pathways. A novel water-soluble metabolite, identified as 26-carboxy-1 alpha,24(OH)(2)D-2, was the presumed terminal degradation product of lot(OH)D-2 synthesized by CYP24A1 via successive 24-hydroxylation, 26-hydroxylation and further oxidation at C-26. This acid was absent in keratinocytes from Cyp24a1 null mice. Slower clearance rates of lot(OH)D, and 1 alpha,24(OH)(2)D-2 relative to 1 alpha,25(OH)(2)D-2 and 1 alpha,25(OH)(2)D-3 were noted, arguing for a role of 24-hydroxylated metabolites in the altered biological activity profile of 1 alpha(OH)D-2. Our findings suggest that CYP24A1 can activate and inactivate vitamin D prodrugs in skin and other target cells in vitro, offering the potential for treatment of hyperproliferative disorders such as psoriasis by topical administration of these prodrugs. (c) 2006 Elsevier B.V. All rights reserved.