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25‐hydroxyvitamin D 3 1alpha‐hydroxylase splice variants in human skin
Author(s) -
Seifert M.,
Tilgen W.,
Reichrath J.
Publication year - 2006
Publication title -
experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 96
eISSN - 1600-0625
pISSN - 0906-6705
DOI - 10.1111/j.1600-0625.2006.00439p.x
Subject(s) - cyp24a1 , vitamin d and neurology , calcitriol , biology , autocrine signalling , alternative splicing , cyp17a1 , paracrine signalling , microbiology and biotechnology , hacat , human skin , vitamin , enzyme , messenger rna , endocrinology , medicine , cell culture , calcitriol receptor , gene , biochemistry , genetics , receptor
1,25‐Dihydroxyvitamin D 3 [1,25(OH) 2 D 3 ], the biologically active metabolite of vitamin D, has been shown to regulate the growth of various cell types, including human keratinocytes. There are two principal enzymes involved in the formation of circulating 1,25(OH) 2 D 3 from vitamin D, the hepatic microsomal or mitochondrial vitamin D 25‐hydroxylase (25‐OHase) and the renal mitochondrial enzyme 1α‐hydroxylase (1α‐OHase) for vitamin D and 25(OH)D 3 , respectively. 25‐hydroxyvitamin D 3 −1α‐hydroxylase (1α‐hydroxylase) catalyses the synthesis of the active form of vitamin D, 1,25‐dihydroxyvitamin D 3 , in the kidney. Recently, extrarenal activity of 1α‐OHase has been reported in various cell types including macrophages, keratinocytes, prostate and colon cancer cells. Local production of calcitriol has been postulated to play an autocrine or paracrine role in vitamin D‐mediated growth control. Previously, we reported mRNA splice variants of the gene encoding the P 450 cytochrome 25‐hydroxyvitamin D 3 ‐1‐hydroxylase in human melanoma cell lines. As already described for other cytochrome P 450 genes, alternative splicing can play a role in regulating the enzyme level and may cause tissue‐specific variations in healthy cells. Using nested touchdown reverse transcription‐PCR (RT‐PCR) and Western blot analysis, we identified CYP27B1 splice variants in cultured normal human melanocytes and keratinocytes (HaCaT) after treatment with UV‐B (10–50 mJ/cm 2 ). Using real‐time RT‐PCR, we quantified the expression of CYP27B1. We identified several splice variants and a clear influence of UV‐B treatment on the expression pattern of CYP27B1 in HaCaT cells.