Steroid hormones are central regulators of a variety of biological processes. According to the free hormone hypothesis, steroids enter target cells by passive diffusion. However, recently we demonstrated that 25(OH) vitamin D(3) complexed to its plasma carrier, the vitamin D-binding protein, enters renal proximal tubules by receptor-mediated endocytosis. Knockout mice lacking the endocytic rece...

The 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) receptor mediates many of the actions of 1,25(OH)2D3 in cells of target tissues. Abnormalities in vitamin D receptor concentration and regulation exist in tissues of subjects with chronic renal failure and end-stage renal disease. There is evidence that inhibitors of vitamin D receptor-1,25(OH)2D3 binding and 1,25(OH)2D3 action are present in dialysat...

The report by Dr Chen and colleagues, published in this issue of Circulation, “Cardiomyocyte-Specific Deletion of the Vitamin D Receptor Gene Results In Cardiac Hypertrophy,” is important and timely.1 This study extends and supports other studies that have demonstrated that vitamin D and the vitamin D receptor (VDR) signaling system possess antihypertrophic activity in the heart. The study also...

background: scleroderma is a chronic connective tissue disease of unknown etiology. vitamin d and parathyroid hormone (pth) that play particular functions in calcium and phosphate homeostasis may be involved in the etiology of this disorder. klotho, the co-receptor of the fibroblast growth factor 23 (fgf-23), can interfere with calcium and phosphate metabolism. the purpose of this study was to ...

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] increases intestinal calcium absorption through events that include binding of 1,25(OH)2D3 to the intracellular vitamin D receptor. In vitro studies using mammalian cell cultures reveal an increase in vitamin D receptor content after exposure to 1,25(OH)2D3. To test the hypothesis that 1,25(OH)2D3 increases enterocyte vitamin D receptor content in vivo, ma...

BACKGROUND Cardiovascular disease is the leading cause of death among those with diabetes mellitus. Vitamin D deficiency is associated with an increased risk of cardiovascular disease in this population. To determine the mechanism by which vitamin D deficiency mediates accelerated cardiovascular disease in patients with diabetes mellitus, we investigated the effects of active vitamin D on macro...