History of the discovery of vitamin D and its active metabolites.
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ABSTRACT:
SUBMITTER: Deluca HF
PROVIDER: S-EPMC3899558 | biostudies-other | 2014 Jan
REPOSITORIES: biostudies-other
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Project description:Prolonged exposure of the skin to UV radiation causes previtamin D3, the initial photoproduct formed by opening of the B ring of 7-dehydrocholesterol, to undergo a second photochemical reaction where the B-ring is reformed giving lumisterol3 (L3), a stereoisomer of 7-dehydrocholesterol. L3 was believed to be an inactive photoproduct of excessive UV radiation whose formation prevents excessive vitamin D production. Recently, we reported that L3 is present in serum and that CYP11A1 can act on L3 producing monohydroxy- and dihydroxy-metabolites which inhibit skin cell proliferation similarly to 1α,25-dihydroxyvitamin D3. In this study we tested the ability of human CYP27A1 to hydroxylate L3. L3 was metabolized by purified CYP27A1 to 3 major products identified as 25-hydroxyL3, (25R)-27-hydroxyL3 and (25S)-27-hydroxyL3, by NMR. These three products were also seen when mouse liver mitochondria containing CYP27A1 were incubated with L3. The requirement for CYP27A1 for their formation by mitochondria was confirmed by the inhibition of their synthesis by 5β-cholestane-3α,7α,12α-triol, an intermediate in bile acid synthesis which serves as an efficient competitive substrate for CYP27A1. CYP27A1 displayed a high kcat for the metabolism of L3 (76 mol product/min/mol CYP27A1) and a catalytic efficiency (kcat/Km) that was 260-fold higher than that for vitamin D3. The CYP27A1-derived hydroxy-derivatives inhibited the proliferation of cultured human melanoma cells and colony formation with IC50 values in the nM range. Thus, L3 is metabolized efficiently by CYP27A1 with hydroxylation at C25 or C27 producing metabolites potent in their ability to inhibit melanoma cell proliferation, supporting that L3 is a prohormone which can be activated by CYP-dependent hydroxylations.
| S-EPMC5992068 | biostudies-literature
Project description:BackgroundVitamin D deficiency is associated with active Crohn's disease (CD). However, it remains unclear if lower 25-hydroxyvitamin D [25(OH)D] concentration is the cause, or consequence, of intestinal inflammation. Existing literature has focused on circulating 25(OH)D rather than the active metabolite 1,25(OH)2D, or its breakdown product, 24,25(OH)2D. We aimed to characterise vitamin D metabolism in a cohort of patients with active and inactive CD.MethodsFifty-four patients with CD and not on corticosteroids or vitamin D supplements, were enrolled in a 6-month prospective cohort study. Sera were collected on enrolment and at 6 months and tested for 25(OH)D, 1,25(OH)2D, 24,25(OH)2D using liquid chromatography tandem mass spectroscopy as well as vitamin-D-binding protein.ResultsThere were no differences in 25(OH)D or 1,25(OH)2D levels between participants with active versus inactive disease. Levels of 24,25(OH)2D were significantly lower in those with active compared with inactive disease (mean 3.9 versus 6.0 µmol/l; p = 0.007) and therefore the ratio of 25(OH)D:24,25(OH)2D was higher (mean 17.3 versus 11.1; p = 0.001). In those patients with active disease who achieved remission, there was a mean increase in 25(OH)D of 32.3 nmol/l (i.e. to a level in the sufficient range) and 24,25(OH)2D of 2.1 µmol/l. These increases were not seen in patients with persistently active or inactive disease.ConclusionLevels of 24,25(OH)2D, but not 25(OH)D, were lower in patients with active CD, and spontaneously increased with resolution of underlying inflammation. The utility of 24,25(OH)2D as a biomarker of disease activity and vitamin D status in CD warrants further exploration.
| S-EPMC6661794 | biostudies-literature
Project description:Vitamin D status, assessed by serum concentration of 25(OH)D, is the prime candidate marker for many disease-association studies, but the interplay between the subsequent 1,25-dihydroxyvitamin D (1,25(OH)2D) and 24,25-dihydroxyvitamin D (24,25(OH)2D) metabolites is unclear. In this study, we conducted an analysis from a large cohort of healthy, physically fit, young army recruits (n = 940). We found a significant, inverse relationship between serum 25(OH)D and 1,25(OH)2D:24,25(OH)2D vitamin D metabolite ratio (VMR) (r2Exp = 0.582, p < 0.0001), and demonstrated a significant association with increasing PTH concentration (p < 0.001). Circannual rhythms were evident for all vitamin D metabolites and VMRs except for 1,25(OH)2D when fitted to Cosinor curves. We estimated 1,25(OH)2D:24,25(OH)2D VMR of ≥35 to be the threshold value for vitamin D insufficiency, and ≥51 to be predictive of vitamin D deficiency. Our three-dimensional model provides mechanistic insight into the vitamin D-PTH endocrine system, and further substantiates the role of 24,25(OH)2D in human physiology. The model sets a new paradigm for vitamin D treatment strategy, and may help the establishment of vitamin D-adjusted PTH reference intervals. The study was approved by the UK Ministry of Defence research ethics committee (MODREC 165/Gen/10 and 692/MoDREC/15). ClinicalTrials.gov Identifier NCT02416895.
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Project description:The story of rickets leading to the discovery of vitamin D is an extraordinary tale, spread over many centuries and involving some remarkable characters with much speculation and a few mysteries, before reaching an exciting climax. It would be wrong to credit a single person as discovering rickets or being the first to describe its features, for reasons that will be set out here. Yet the emergence of the term 'rickets' is as important as the discovery of vitamin D itself and the possible causes of its deficiency. It permitted identification of a hitherto ill-defined disease entity, typically occurring in infants and children. It also provided a way for deciding if features of diseases that had been described earlier in the history of medicine could be seen as the symptoms and signs of related conditions.
| S-EPMC3899557 | biostudies-other
Project description:Assay variability has been cited as an obstacle to establishing optimal vitamin D exposure. As part of the Vitamin D Standardization Program (VDSP) effort to standardize the measurement of total 25-hydroxyvitamin D [25(OH)D], the value assignment of total 25(OH)D in 50 single-donor serum samples was performed using two isotope-dilution LC with tandem MS methods. Both methods are recognized as reference measurement procedures (RMPs) by the Joint Committee for Traceability in Laboratory Medicine. These samples and their assigned values serve as the foundation for several aspects of the VDSP. To our knowledge, this is the first time that two RMPs have been used to assign 25(OH)D values to such a large number of serum samples.
| S-EPMC5601309 | biostudies-literature
Project description:BackgroundProteinuria has been associated with progression of renal disease and increased morbidity and mortality in dogs and people. In people, proteinuria also has been associated with hypovitaminosis D. Little is known about the relationship between vitamin D metabolism and proteinuria in dogs.ObjectivesTo further elucidate vitamin D status in dogs with protein-losing nephropathy (PLN) and minimal to no azotemia. We hypothesized that vitamin D metabolites would be lower in dogs with PLN compared to healthy dogs.AnimalsTwenty-three client-owned adult dogs with PLN and 10 healthy control dogs.MethodsSerum 25-hydroxyvitamin D (25[OH]D), 1,25-dihydroxyvitamin D (1,25[OH]2 D), 24,25-dihydroxyvitamin D (24,25[OH]2 D), serum vitamin D binding protein (VDBP), and urine 25(OH)D concentrations were measured.ResultsCompared to healthy dogs, dogs with PLN had lower concentrations of all vitamin D metabolites (P < .01). Correlations (rho; 95% confidence interval [CI]) in dogs with PLN are reported. Serum 25(OH)D and 24,25(OH)2 D concentrations were positively correlated with albumin (r = 0.47; 0.07-0.74), and 24,25(OH)2 D was negatively correlated with urine protein-to-creatinine ratio (UPC; r = -0.54; -0.78 to -0.16). Urine 25(OH)D-to-creatinine ratio was negatively correlated with serum albumin concentration (r = -0.77; -0.91 to -0.50) and positively correlated with UPC (r = 0.79; 0.53-0.91). Serum VDBP concentration was positively correlated with serum albumin concentration (r = 0.53; 0.05-0.81).Conclusions and clinical importanceDogs with PLN have decreased serum concentrations of vitamin D metabolites. Urine 25(OH)D-to-creatinine ratio and UPC are correlated in PLN dogs. Future studies are needed to assess additional management strategies for dogs with PLN.
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Project description:Studies have shown that vitamin D can enhance glucose-stimulated insulin secretion (GSIS) and change the expression of genes in pancreatic β-cells. Still the mechanisms linking vitamin D and GSIS are unknown. We used an established β-cell line, INS1E. INS1E cells were pre-treated with 10 nM 1,25(OH)2vitamin D or 10 nM 25(OH)vitamin D for 72 hours and stimulated with 22 mM glucose for 60 minutes. RNA was extracted for gene expression analysis.
2020-02-19 | GSE145460 | GEO