scholarly journals Influence of the Vitamin D-binding Protein on the Serum Concentration of 1,25-Dihydroxyvitamin D3

1981 ◽  
Vol 67 (3) ◽  
pp. 589-596 ◽  
Author(s):  
Roger Bouillon ◽  
Frans A. Van Assche ◽  
Hugo Van Baelen ◽  
Walter Heyns ◽  
Pieter De Moor
Keyword(s):  
Vitamin D ◽  
Serum Concentration ◽  
Binding Protein ◽  
Vitamin D Binding Protein ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3

Effects of vitamin D-binding protein on bone resorption stimulated by 1,25 dihydroxyvitamin D3

1990 ◽  
Vol 47 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Socorro Vargas ◽  
Roger Bouillon ◽  
Hugo Van Baelen ◽  
Lawrence G. Raisz
Keyword(s):  
Vitamin D ◽  
Bone Resorption ◽  
Binding Protein ◽  
Vitamin D Binding Protein ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3

Vitamin D metabolism in osteoporotic women during treatment with estrogen, an anabolic steroid, or calcitonin

1990 ◽  
Vol 122 (6) ◽  
pp. 715-721 ◽  
Author(s):  
Dorthe Hartwell ◽  
Christian Hassager ◽  
Kirsten Overgaard ◽  
Bente Juel Riis ◽  
Jan Pødenphant ◽  
...  
Keyword(s):  
Vitamin D ◽  
Serum Concentration ◽  
Binding Protein ◽  
Total Serum ◽  
Vitamin D Metabolites ◽  
Nandrolone Decanoate ◽  
Vitamin D Binding Protein ◽  
Double Blind ◽  
Vitamin D Metabolism ◽  
Norethisterone Acetate

Abstract. We assessed the effects of a continuous oral combination of estradiol and norethisterone acetate, nandrolone decanoate, or salmon calcitonin on the vitamin D endocrine system. One hundred and nineteen postmenopausal women, aged 55-75 years, with at least one osteoporotic fracture, were randomly allocated to one year of treatment with estradiol and norethisterone acetate, nandrolone decanoate, or calcitonin, all drugs with a beneficial effect on bone. All three trials were double-blind and placebo-controlled; 104 women (87%) completed the study. We measured the total serum concentration of 1,25-dihydroxyvitamin D (1,25(OH)2D) and vitamin D-binding protein, and estimated the free 1,25(OH)2D index and the "24-hydroxylase activity" initially, and at 6 and 12 months. Furthermore, the 24-h urinary excretions of calcium, phosphate, and adenosine 3'-5'-cyclic monophosphate were assessed initially and at 12 months. The serum concentration of vitamin D-binding protein and 1,25(OH)2D increased transiently during estradiol and norethisterone acetate treatment and vitamin D-binding protein decreased transiently during nandrolone decanoate treatment. None of the other parameters were significantly affected by any of the three treatments. The risk of type II errors was below 10 per cent for all vitamin D measurements. We conclude that the vitamin D metabolites are unlikely to be of major importance for the mechanism by which these drugs exert their positive skeletal effects.

scholarly journals Cellular Expression Levels of the Vitamin D Receptor Are Critical to Its Transcriptional Regulation by the Pituitary Transcription Factor Pit-1

2007 ◽  
Vol 21 (7) ◽  
pp. 1513-1525 ◽  
Author(s):  
Samuel Seoane ◽  
Isabel Ben ◽  
Viviana Centeno ◽  
Roman Perez-Fernandez
Keyword(s):  
Vitamin D ◽  
Transcription Factor ◽  
Transcriptional Regulation ◽  
Vitamin D Receptor ◽  
Binding Protein ◽  
Target Cells ◽  
Dihydroxyvitamin D3 ◽  
Expression Levels ◽  
1,25 Dihydroxyvitamin D3 ◽  
Mcf 7

Abstract The biological role of 1,25-dihydroxyvitamin D3 has generally been related to calcium homeostasis, but this hormone also has fundamental effects on processes of cellular proliferation and differentiation. The genomic actions of 1,25-dihydroxyvitamin D3 are mediated by the vitamin D receptor (VDR) present in target cells. However, VDR transcriptional regulation is not well understood, probably attributable to the complexity of the VDR gene and its promoter. In the present study, it is demonstrated that administration of the pituitary transcription factor Pit-1 (originally found in the pituitary gland but also present in other nonpituitary cell types and tissues) to the MCF-7 (human breast adenocarcinoma) cell line induces a significant increase in VDR mRNA and protein levels. Conversely, Pit-1-targeted small interference RNA markedly reduced expression of VDR in MCF-7 cells. Reporter gene assays demonstrated that the effect of Pit-1 is mediated by its binding to a region located between −254 and −246 bp from the VDR transcription start site. Selective mutations of this site completely abolished VDR transcription. Chromatin immunoprecipitation analysis showed that binding of Pit-1 to the VDR promoter leads additionally to recruitment of cAMP response element-binding protein binding protein, acetylated histone H4, and RNA polymerase II. Surprisingly, Pit-1 binding also recruits VDR protein to the VDR promoter. Using several cell lines with different levels of VDR expression, it was demonstrated that up-regulation of VDR transcription by Pit-1 is dependent on the presence of VDR protein, suggesting that transcriptional expression of VDR in a given cell type is dependent on, among other factors, its own expression levels.

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