Wavelength-dependent induction of CYP24A1-mRNA after UVB-triggered calcitriol synthesis in cultured human keratinocytes
Wavelength-dependent induction of CYP24A1-mRNA after UVB-triggered calcitriol synthesis in cultured human keratinocytes
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DOI：
10.1038/sj.jid.5700493
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发表时间：
2007-01-01
影响因子：
6.5
通讯作者：
Meurer, Michael
中科院分区：
文献类型：
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作者：
Baer, Michael;Domaschke, Doerte;Meurer, Michael
我们实验室早期的研究表明，UVB照射培养的人角质形成细胞可诱导7-脱氢胆固醇（7-DHC）转化为具有激素活性的1 α，25-二羟基维生素D-3（骨化三醇）。在本研究中，我们利用实时PCR技术研究了uvb触发的骨化三醇生产对维生素D-3羟化酶分解代谢25-羟基维生素D-3-24-羟化酶（CYP24A1）、活性维生素D-3-25-羟化酶（CYP27A1）和25-羟基维生素D-3-1 - α -羟化酶（CYP27B1）基因表达的影响。我们的研究结果表明，在添加7-DHC的培养的人角质形成细胞中，CYP24A1-mRNA具有明显的波长依赖性诱导作用，这与HPLC和放射免疫分析法检测到的在300 nm左右产生骨化三醇时的最佳光谱相似。由于实时PCR的高灵敏度，我们提供了波长依赖性诱导CYP24A1-mRNA的证据，即使在7- dhc缺陷的角质形成细胞中也是如此。有趣的是，我们在未辐照的角质形成细胞中发现了强烈但短暂的CYP24A1-mRNA诱导，随后加速了细胞增殖。相比之下，UVB和骨化三醇对CYP27A1和CYP27B1基因表达无影响。我们从这些实验中得出结论，维生素D-3羟化酶的组成基因表达，而分解代谢酶CYP24A1则明显受到中波紫外线、骨化三醇和细胞增殖的调节。如果在蛋白质水平上得到证实，这些发现可能对健康和疾病中表皮维生素D-3代谢及其被UVB调节产生影响。
Earlier investigations in our laboratory have demonstrated that UVB irradiation of cultured human keratinocytes induces the conversion of 7-dehydrocholesterol (7-DHC) to hormonally active 1 alpha,25-dihydroxyvitamin D-3 (calcitriol). In the research presented here, we have investigated the influence of UVB-triggered calcitriol production on gene expression of the vitamin D-3 hydroxylating enzymes catabolic 25-hydroxyvitamin-D-3-24-hydroxylase (CYP24A1), active vitamin-D-3-25-hydroxylase (CYP27A1), and 25-hydroxyvitamin-D-3-1 alpha-hydroxylase (CYP27B1) using real-time PCR. Our results demonstrate a marked and wavelength-dependent induction of CYP24A1-mRNA in cultured human keratinocytes supplemented with 7-DHC, which parallels the spectral optimum at about 300 nm of calcitriol production as detected by HPLC and radioimmunoassay. Owing to the high sensitivity of real-time PCR, we provide evidence of a wavelength-dependent induction of CYP24A1-mRNA even in 7-DHC-deficient keratinocytes. Interestingly, we have found a strong but transient induction of CYP24A1-mRNA in non-irradiated keratinocytes, followed by accelerated cell proliferation. In contrast, UVB and calcitriol had no effect on gene expression of CYP27A1 and CYP27B1. We conclude from these experiments a constitutive gene expression of the vitamin D-3 hydroxylases, whereas the catabolic enzyme CYP24A1 is markedly regulated by UVB, calcitriol, and perhaps cell proliferation. If confirmed at protein level, these findings could have an impact on epidermal vitamin D-3 metabolism and its modulation by UVB in health and disease.