Down-regulation by nuclear factor κB of human 25-hydroxyvitamin D3 1α-hydroxylase promoter
Down-regulation by nuclear factor κB of human 25-hydroxyvitamin D3 1α-hydroxylase promoter
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DOI：
10.1210/me.2002-0441
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发表时间：
2004-10-01
影响因子：
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通讯作者：
Jakob, F
中科院分区：
文献类型：
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作者：
Ebert, R;Jovanovic, M;Jakob, F
1，25-（OH）（2）维生素D-3对钙稳态和细胞分化很重要。肝源性25（OH）维生素D-3活化的关键酶是25-羟基维生素D-3 1 α-羟化酶。它主要在肾脏中表达，但也在外周组织中表达。将1 α-羟化酶启动子的1413-bp片段克隆到荧光素酶载体pGL 2basic和pGL 3basic中。序列分析表明，与已发表的序列相比，在5个对照组中发现了4个碱基的交换和3个碱基的缺失。计算机模拟启动子分析揭示了17个推定的核因子（NF）kappaB位点，其中10个在EMSA实验中被发现与NF kappaB结合。NF κ B p50和p65亚基的共转染导致全长构建体以及一系列5 ′-缺失构建体的启动子活性显著降低。最远的3 '-定位NF κ B反应元件的删除几乎取消NF κ B反应。用NF κ B抑制剂柳氮磺胺吡啶处理人胚肾293细胞，导致1 α-羟化酶mRNA的产生增强。通过NF κ B信号转导下调1 α-羟化酶启动子可能有助于炎症相关骨质减少/骨质疏松症的发病机制。
1,25-(OH)(2) vitamin D-3 is important for calcium homeostasis and cell differentiation. The key enzyme for the activation of liver-derived 25( OH) vitamin D-3 is 25- hydroxyvitamin D-3 1alpha-hydroxylase. It is expressed mainly in the kidney but also in peripheral tissues. A 1413-bp fragment of the 1alpha-hydroxylase promoter was cloned into luciferase vectors pGL2basic and pGL3basic. Sequence analyses revealed four base exchanges and three base deletions compared with the published sequence which were identically found in five control persons. In silico promoter analyses revealed 17 putative nuclear factor (NF)kappaB sites, 10 of which were found to bind NFkappaB in EMSA experiments. Cotransfection of NFkappaB p50 and p65 subunits resulted in dramatic reduction of the promoter activity of the full-length construct as well as a series of 5'-deletion constructs. Deletion of the farmost 3'-situated NFkappaB-responsive element almost abolished NFkappaB responsiveness. Treatment of human embryonic kidney 293 cells with sulfasalazine, a NFkappaB inhibitor, resulted in enhanced 1alpha-hydroxylase mRNA production. Down-regulation of 1alpha-hydroxylase promoter through NFkappaB signaling may contribute to the pathogenesis of inflammation-associated osteopenia/osteoporosis.