Hormonal regulation of 25-hydroxyvitamin D3-lα-hydroxylase and 24-hydroxylase gene transcription in opossum kidney cells
Hormonal regulation of 25-hydroxyvitamin D3-lα-hydroxylase and 24-hydroxylase gene transcription in opossum kidney cells
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DOI：
10.1016/s0003-9861(02)00636-7
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发表时间：
2003-01-15
影响因子：
3.9
通讯作者：
Boltz, MA
中科院分区：
文献类型：
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作者：
Armbrecht, HJ;Hodam, TL;Boltz, MA
在肾脏中，25-羟基维生素D-3（25（OH）D）通过25（OH）D-3- 1 α-羟化酶转化为1，25-二羟基维生素D-3（1，25（OH）2D），该酶含有末端细胞色素P450（CYP 1 α）（系统名称：CYP 27 B1）。同样，肾脏也通过24-羟化酶产生24，25-二羟基维生素D-3和1，24，25-三羟基维生素D-3，该酶的末端细胞色素P450是CYP 24。本研究的目的是表征甲状旁腺激素（PTH）和1，25（OH）2D在肾脏中对CYP 1 α和CYP 24基因的转录调控。将启动子-报告基因构建体转染到负鼠肾（OK）细胞中，所述负鼠肾（OK）细胞是具有内源性PTH和1，25（OH）2D受体的肾近端小管细胞系。PTH和毛喉素通过cAMP依赖性途径刺激CYP 1 α启动子活性，该途径通过CREB（cAMP依赖性反应元件结合蛋白）的磷酸化起作用。这种刺激并不需要新的蛋白质合成，但可能是由短寿命的蛋白质调制。1，25（OH）2D适度抑制基础和毛喉素刺激的CYP 1 α启动子活性。PTH和毛喉素对CYP 1 α启动子活性的刺激可以解释这些激素对肾脏CYP 1 α mRNA水平的影响。1，25（OH）2D和PTH均能提高转染细胞中CYP 24启动子的活性，但二者之间无相互作用。1，25（OH）2D和PTH对启动子活性的适度影响及其缺乏相互作用不能解释这些激素对肾脏CYP 24 mRNA水平的影响。这表明肾脏中可能存在重要的CYP 24 mRNA转录后调节。(C)2002 Elsevier Science（美国）。All rights reserved.
In the kidney, 25-hydroxyvitamin D-3 (25(OH)D) is converted to 1,25-dihydroxyvitamin D-3 (1,25(OH)2D) by the 25(OH)D-3-1alpha-hydroxylase enzyme, which contains a terminal cytochrome P450 (CYP1alpha) (systematic name: CYP27B1). Likewise, the kidney also produces 24,25-dihydroxyvitamin D-3 and 1,24,25-trihydroxyvitamin D-3 via a 24-hydroxylase whose terminal cytochrome P450 is CYP24. The purpose of this study was to characterize the transcriptional regulation of the CYP1alpha and CYP24 genes by parathyroid hormone (PTH) and 1,25(OH)2D in the kidney. Promoter-reporter gene constructs were transfected into opossum kidney (OK) cells, a renal proximal tubular cell line with endogenous PTH and 1,25(OH)2D receptors. PTH and forskolin stimulated CYP1alpha promoter activity via a cAMP-dependent pathway acting through the phosphorylation of CREB (cAMP-dependent response element-binding protein). This stimulation did not require new protein synthesis but may be modulated by short-lived proteins. 1,25(OH)2D modestly inhibited basal and forskolin-stimulated CYP1alpha promoter activity. The stimulation of CYP1alpha promoter activity by PTH and forskolin can account for the effect of these hormones on renal CYP1alpha mRNA levels. CYP24 promoter activity in transfected cells was increased by both 1,25(OH)2D and PTH, but there was no interaction between the two. The modest effects of 1,25(OH)2D and PTH on promoter activity and their lack of interaction do not account for the effects of these hormones on renal CYP24 mRNA levels. This suggests that there may be important posttranscriptional regulation of CYP24 mRNA in the kidney. (C) 2002 Elsevier Science (USA). All rights reserved.