scholarly journals Vitamin D Receptor in Osteoblasts Is a Negative Regulator of Bone Mass Control

Endocrinology ◽  
2013 ◽  
Vol 154 (3) ◽  
pp. 1008-1020 ◽  
Author(s):  
Yoko Yamamoto ◽  
Tatsuya Yoshizawa ◽  
Toru Fukuda ◽  
Yuko Shirode-Fukuda ◽  
Taiyong Yu ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Mass ◽  
Vitamin D Receptor ◽  
Calcium Absorption ◽  
Mineral Metabolism ◽  
Direct Action ◽  
Active Form ◽  
Negative Regulator ◽  
Collagen Promoter ◽  
Mass Increase

Abstract The physiological and beneficial actions of vitamin D in bone health have been experimentally and clinically proven in mammals. The active form of vitamin D [1α,25(OH)2D3] binds and activates its specific nuclear receptor, the vitamin D receptor (VDR). Activated VDR prevents the release of calcium from its storage in bone to serum by stimulating intestinal calcium absorption and renal reabsorption. However, the direct action of VDR in bone tissue is poorly understood because serum Ca2+ homeostasis is maintained through tightly regulated ion transport by the kidney, intestine, and bone. In addition, conventional genetic approaches using VDR knockout (VDR-KO, VDR−/−) mice could not identify VDR action in bone because of the animals' systemic defects in calcium metabolism. In this study, we report that systemic VDR heterozygous KO (VDR+/L−) mice generated with the Cre/loxP system as well as conventional VDR heterozygotes (VDR+/−) showed increased bone mass in radiological assessments. Because mineral metabolism parameters were unaltered in both types of mice, these bone phenotypes imply that skeletal VDR plays a role in bone mass regulation. To confirm this assumption, osteoblast-specific VDR-KO (VDRΔOb/ΔOb) mice were generated with 2.3 kb α1(I)-collagen promoter-Cre transgenic mice. They showed a bone mass increase without any dysregulation of mineral metabolism. Although bone formation parameters were not affected in bone histomorphometry, bone resorption was obviously reduced in VDRΔOb/ΔOb mice because of decreased expression of receptor activator of nuclear factor kappa-B ligand (an essential molecule in osteoclastogenesis) in VDRΔOb/ΔOb osteoblasts. These findings establish that VDR in osteoblasts is a negative regulator of bone mass control.

Vitamin D receptor polymorphisms and bone mass indices in post menarcheal indian adolescent girls

2013 ◽  
Author(s):  
Sunil Kumar Kota ◽  
Lalit Kumar Meher ◽  
Sruti Jammula ◽  
Kirtikumar D Modi
Keyword(s):  
Vitamin D ◽  
Bone Mass ◽  
Adolescent Girls ◽  
Vitamin D Receptor

scholarly journals Vitamin D-Mediated Hypercalcemia: Mechanisms, Diagnosis, and Treatment

2016 ◽  
Vol 37 (5) ◽  
pp. 521-547 ◽  
Author(s):  
Peter J. Tebben ◽  
Ravinder J. Singh ◽  
Rajiv Kumar
Keyword(s):  
Vitamin D ◽  
Vitamin D Receptor ◽  
Active Form ◽  
Elevated Serum ◽  
Diagnosis And Treatment ◽  
Vitamin D Metabolites ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Stone Formers ◽  
25 Hydroxyvitamin D

AbstractHypercalcemia occurs in up to 4% of the population in association with malignancy, primary hyperparathyroidism, ingestion of excessive calcium and/or vitamin D, ectopic production of 1,25-dihydroxyvitamin D [1,25(OH)2D], and impaired degradation of 1,25(OH)2D. The ingestion of excessive amounts of vitamin D3 (or vitamin D2) results in hypercalcemia and hypercalciuria due to the formation of supraphysiological amounts of 25-hydroxyvitamin D [25(OH)D] that bind to the vitamin D receptor, albeit with lower affinity than the active form of the vitamin, 1,25(OH)2D, and the formation of 5,6-trans 25(OH)D, which binds to the vitamin D receptor more tightly than 25(OH)D. In patients with granulomatous disease such as sarcoidosis or tuberculosis and tumors such as lymphomas, hypercalcemia occurs as a result of the activity of ectopic 25(OH)D-1-hydroxylase (CYP27B1) expressed in macrophages or tumor cells and the formation of excessive amounts of 1,25(OH)2D. Recent work has identified a novel cause of non-PTH-mediated hypercalcemia that occurs when the degradation of 1,25(OH)2D is impaired as a result of mutations of the 1,25(OH)2D-24-hydroxylase cytochrome P450 (CYP24A1). Patients with biallelic and, in some instances, monoallelic mutations of the CYP24A1 gene have elevated serum calcium concentrations associated with elevated serum 1,25(OH)2D, suppressed PTH concentrations, hypercalciuria, nephrocalcinosis, nephrolithiasis, and on occasion, reduced bone density. Of interest, first-time calcium renal stone formers have elevated 1,25(OH)2D and evidence of impaired 24-hydroxylase-mediated 1,25(OH)2D degradation. We will describe the biochemical processes associated with the synthesis and degradation of various vitamin D metabolites, the clinical features of the vitamin D-mediated hypercalcemia, their biochemical diagnosis, and treatment.

Is BsmI vitamin-D receptor gene polymorphism associated with combined bone mass in spine and proximal femur in icelandic women?

1996 ◽  
Vol 6 (S1) ◽  
pp. 157-157
Author(s):  
G. Sigurdsson ◽  
D. N. Magnúsdóttir ◽  
J. O. Kristinsson ◽  
K. Kristjánsson ◽  
I. Olaisson
Keyword(s):  
Vitamin D ◽  
Gene Polymorphism ◽  
Bone Mass ◽  
Vitamin D Receptor ◽  
Proximal Femur ◽  
Receptor Gene ◽  
Vitamin D Receptor Gene ◽  
Receptor Gene Polymorphism

scholarly journals The Role of Vitamin D and Vitamin D Receptor in Immunity toLeishmania majorInfection

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
James P. Whitcomb ◽  
Mary DeAgostino ◽  
Mark Ballentine ◽  
Jun Fu ◽  
Martin Tenniswood ◽  
...  
Keyword(s):  
Vitamin D ◽  
Immune Responses ◽  
Vitamin D Receptor ◽  
Leishmania Major ◽  
Active Form ◽  
Wild Type ◽  
Vitamin D Signaling ◽  
Deficient Mice ◽  
Th 1

Vitamin D signaling modulates a variety of immune responses. Here, we assessed the role of vitamin D in immunity to experimental leishmaniasis infection in vitamin D receptor-deficient mice (VDRKO). We observed that VDRKO mice on a genetically resistant background have decreasedLeishmania major-induced lesion development compared to wild-type (WT) mice; additionally, parasite loads in infected dermis were significantly lower at the height of infection. Enzymatic depletion of the active form of vitamin D mimics the ablation of VDR resulting in an increased resistance toL. major. Conversely, VDRKO or vitamin D-deficient mice on the susceptible Th2-biased background had no change in susceptibility. These studies indicate vitamin D deficiency, either through the ablation of VDR or elimination of its ligand, 1,25D3, leads to an increase resistance toL. majorinfection but only in a host that is predisposed for Th-1 immune responses.

Vitamin D and atopic dermatitis

2021 ◽  
pp. 26-36
Author(s):  
Mariya Aleksandrovna Bochkareva ◽  
Svetlana Viktorovna Bulgakova ◽  
Anula Viktorovna Melikova
Keyword(s):  
Vitamin D ◽  
Atopic Dermatitis ◽  
Mineral Metabolism ◽  
Active Form ◽  
Allergic Diseases ◽  
The Body ◽  
Biological Processes ◽  
Skeletal System ◽  
Rapid Spread ◽  
Global Health Problem

Allergic diseases, in particular, atopic dermatitis, are becoming a global health problem due to the rapid spread, both as an independent disease and as a predictor of the development of bronchial asthma. Discovery of all the processes of the pathogenesis of atopic dermatitis will provide great opportunities for the prevention and treatment of this disease. In this regard, special attention is paid to vitamin D, which becomes more and more popular all over the world every year. In addition to the known and studied consequences of vitamin D deficiency for skeletal system health and mineral metabolism, recent studies have shown that calcitriol, the active form of vitamin D, is involved in many biological processes in the body, including the regulation of the immune system. The discovery of the vitamin D receptor on various cells of the body opens up new prospects for studying the course of various diseases, such as diabetes mellitus, vascular atherosclerosis, obesity, autoimmune diseases, oncology and allergies. The review will be devoted to this problem. 38 foreign and 2 domestic sources are cited.

scholarly journals Novel vitamin D analogs that modulate leukemic cell growth and differentiation with little effect on either intestinal calcium absorption or bone mobilization

Blood ◽  
1989 ◽  
Vol 74 (1) ◽  
pp. 82-93 ◽  
Author(s):  
JY Zhou ◽  
AW Norman ◽  
M Lubbert ◽  
ED Collins ◽  
MR Uskokovic ◽  
...  
Keyword(s):  
Vitamin D ◽  
Mechanism Of Action ◽  
Vitamin D3 ◽  
Clonal Growth ◽  
Calcium Absorption ◽  
Active Form ◽  
Intestinal Calcium Absorption ◽  
Leukemic Cells ◽  
Binding Studies ◽  
Vitamin D Analogs

Abstract Induction of terminal differentiation of leukemic and preleukemic cells is a therapeutic approach to leukemia and preleukemia. The 1 alpha, 25- dihydroxyvitamin D3 [1,25(OH)2D3], the hormonally active form of vitamin D3, can induce differentiation and inhibit proliferation of leukemia cells, but concentrations required to achieve these effects cause life-threatening hypercalcemia. Seven new analogs of 1,25(OH)2D3 were discovered to be either equivalent or more potent than 1,25(OH)2D3 as assessed by: (a) inhibition of clonal proliferation of HL-60, EM-2, U937, and patients' myeloid leukemic cells: and (b) induction of differentiation of HL-60 promyelocytes. Furthermore, these analogs stimulated clonal growth of normal human myeloid stem cells. The most potent analog, 1,25-dihydroxy-16ene-23yne-vitamin D3, was about fourfold more potent than 1,25(OH)2D3. This analog decreased clonal growth and expression of c-myc oncogene in HL-60 cells by 50% within ten hours of exposure. Effects on calcium metabolism of these novel analogs in vivo was assessed by intestinal calcium absorption (ICA) and bone calcium mobilization (BCM). Each of the analogs mediated markedly less (10 to 200-fold) ICA and BCM as compared with 1,25(OH)2D3. To gain insight into the possible mechanism of action of these new analogs, receptor binding studies were done with 1,25(OH)2–16ene-23yne-D3 and showed that it competed only about 60% as effectively as 1,25(OH)2D3 for 1,25(OH)2D3 receptors present in HL-60 cells and 98% as effective as 1,25(OH)2D3 for receptors present in chick intestinal cells. In summary, we have discovered seven novel vitamin D analogs that are more potent than the physiologic 1,25(OH)2D3 as measured by a variety of hematopoietic assays. In contrast, these compounds appear to have the potential to be markedly less toxic (induction of hypercalcemia). These novel vitamin D compounds may be superior to 1,25(OH)2D3 in a number of clinical situations including leukemia/preleukemia; they will provide a tool to dissect the mechanism of action of vitamin D seco-steroids in promoting cellular differentiation.

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