title: Molecular cloning, characterization, and promoter analysis of the human 25-hydroxyvitamin D3-1alpha-hydroxylase gene.
abstract: The human 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-OHase) gene has been cloned. It contained nine exons and eight introns spanning approximately 6.5 kb and a 1.4-kb 5'-flanking region. The 5'-flanking region contains consensus or highly conserved sequences for TATA, Pu, and CCAAT boxes, four cAMP response elements, two activator protein-1 (AP-1) response elements, two AP-2 response elements, three specific protein-1 (Sp1) response elements, and four NF-kappaB binding sites, but no vitamin D response element. By using luciferase reporter gene constructs of truncated forms of the 1alpha-OHase promoter transfected into a modified pig kidney cell line, AOK-B50, we identified regulatory regions of the 1.4-kb 1alpha-OHase promoter for parathyroid hormone 1-34 [PTH(1-34)], forskolin, and 1,25-hydroxyvitamin D3 [1,25(OH)2D3]. The 1.4-kb 1alpha-OHase promoter (AN1) modestly (1.7-fold) induced luciferase activity, whereas 1,100- (AN2), 827- (AN3), 672- (AN4), 463-(AN5), and 363-bp (AN6)-truncated promoters greatly stimulated luciferase activity by 494-fold, 18.4-fold, 55.3-fold, 643-fold, and 56.4-fold, respectively. PTH(1-34) and forskolin stimulated the activity of all constructs to varying degrees with significantly greater responsiveness for both compounds on AN2 and AN5. 1,25(OH)2D3 suppressed PTH(1-34)-induced activity on AN2 and AN5 constructs by 58% and 52%, respectively, but had no effect on the other constructs. These studies characterize the regulatory regions of the human 1alpha-OHase gene and provide insight into the physiologic basis for regulation of the expression of this gene by PTH and 1,25(OH)2D3.
authors.affiliation: Vitamin D, Skin and Bone Research Laboratory, Endocrinology, Nutrition, and Diabetes Section, Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA.
authors.forename: X F
authors.initials: XF
authors.lastname: Kong
authors.forename: X H
authors.initials: XH
authors.lastname: Zhu
authors.forename: Y L
authors.initials: YL
authors.lastname: Pei
authors.forename: D M
authors.initials: DM
authors.lastname: Jackson
authors.forename: M F
authors.initials: MF
authors.lastname: Holick
mesh_terms: D001483:Base Sequence; D053493:Cholestanetriol 26-Monooxygenase; D003001:Cloning, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D013250:Steroid Hydroxylases; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase