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Meyer MB, Lee SM, Cichanski SR, Cobice DF, Pike JW. Spatial detection and consequences of nonrenal calcitriol production as assessed by targeted mass spectrometry imaging. JCI Insight 2024; 9:e181763. [PMID: 38916957 PMCID: PMC11383599 DOI: 10.1172/jci.insight.181763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/20/2024] [Indexed: 06/27/2024] Open
Abstract
The immune benefits of vitamin D3 supplementation beyond calcium and phosphate maintenance are highly clinically debated. Kidney expression of CYP27B1 is the source of endocrine, circulating 1,25(OH)2D3 (active form of vitamin D) that maintains serum calcium and phosphate. 1,25(OH)2D3 may also be made by the CYP27B1 enzyme in nonrenal cells, like immune cells, in a process driven by cellular availability of 25(OH)D3 and inflammation. Due to the endocrine nature of 1,25(OH)2D3 in circulation, it is difficult to discern between these 2 sources. We recently created a regulatory deletion model of Cyp27b1 (M1/M21-DIKO) where mice have normal inflammatory-regulated Cyp27b1 expression in nonrenal tissues (unlike global Cyp27b1-KO) but no expression within the kidney. Here, utilizing on-tissue chemical derivatization and matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI), we investigated the distribution of 1,25(OH)2D3 and 25(OH)D3 in the kidney, liver, spleen, and thymus. MALDI-MSI demonstrated increased 1,25(OH)2D3 in nonrenal tissues such as the spleen after vitamin D3 supplementation in M1/M21-DIKO mice. Additionally, from this, we found increased Il4 and decreased Tnfa in the spleen after vitamin D3 supplementation. Taken together, these data demonstrate nonrenal production of 1,25(OH)2D3 in vivo and provide a consequence of vitamin D3 supplementation and nonrenal 1,25(OH)2D3 production in cytokine changes.
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Affiliation(s)
- Mark B Meyer
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Seong Min Lee
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Shannon R Cichanski
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Diego F Cobice
- Mass Spectrometry Centre, Biomedical Sciences Research Institute (BMSRI), School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Jeong SP, Sharma N, An SSA. Role of Calcitriol and Vitamin D Receptor ( VDR) Gene Polymorphisms in Alzheimer's Disease. Int J Mol Sci 2024; 25:4806. [PMID: 38732025 PMCID: PMC11084202 DOI: 10.3390/ijms25094806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 02/21/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024] Open
Abstract
Alzheimer's disease (AD) is characterized by amyloid beta (Aβ) buildup and neuronal degeneration. An association between low serum vitamin D levels and an increased risk of AD has been reported in several epidemiological studies. Calcitriol (1,25-dihydroxycholecalciferol) is the active form of vitamin D, and is generated in the kidney and many other tissues/organs, including the brain. It is a steroid hormone that regulates important functions like calcium/phosphorous levels, bone mineralization, and immunomodulation, indicating its broader systemic significance. In addition, calcitriol confers neuroprotection by mitigating oxidative stress and neuroinflammation, promoting the clearance of Aβ, myelin formation, neurogenesis, neurotransmission, and autophagy. The receptors to which calcitriol binds (vitamin D receptors; VDRs) to exert its effects are distributed over many organs and tissues, representing other significant roles of calcitriol beyond sustaining bone health. The biological effects of calcitriol are manifested through genomic (classical) and non-genomic actions through different pathways. The first is a slow genomic effect involving nuclear VDR directly affecting gene transcription. The association of AD with VDR gene polymorphisms relies on the changes in vitamin D consumption, which lowers VDR expression, protein stability, and binding affinity. It leads to the altered expression of genes involved in the neuroprotective effects of calcitriol. This review summarizes the neuroprotective mechanism of calcitriol and the role of VDR polymorphisms in AD, and might help develop potential therapeutic strategies and markers for AD in the future.
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Affiliation(s)
| | - Niti Sharma
- Bionano Research Institute, Gachon University, 1342 Seongnam-daero, Sujung-gu, Seongnam-si 461-701, Republic of Korea
| | - Seong Soo A. An
- Bionano Research Institute, Gachon University, 1342 Seongnam-daero, Sujung-gu, Seongnam-si 461-701, Republic of Korea
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Donati S, Palmini G, Aurilia C, Falsetti I, Marini F, Giusti F, Iantomasi T, Brandi ML. Calcifediol: Mechanisms of Action. Nutrients 2023; 15:4409. [PMID: 37892484 PMCID: PMC10610216 DOI: 10.3390/nu15204409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/11/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
Due to its essential role in calcium and phosphate homeostasis, the secosteroid hormone calcitriol has received growing attention over the last few years. Calcitriol, like other steroid hormones, may function through both genomic and non-genomic mechanisms. In the traditional function, the interaction between the biologically active form of vitamin D and the vitamin D receptor (VDR) affects the transcription of thousands of genes by binding to repeated sequences present in their promoter region, named vitamin D-responsive elements (VDREs). Non-transcriptional effects, on the other hand, occur quickly and are unaffected by inhibitors of transcription and protein synthesis. Recently, calcifediol, the immediate precursor metabolite of calcitriol, has also been shown to bind to the VDR with weaker affinity than calcitriol, thus exerting gene-regulatory properties. Moreover, calcifediol may also trigger rapid non-genomic responses through its interaction with specific membrane vitamin D receptors. Membrane-associated VDR (mVDR) and protein disulfide isomerase family A member 3 (Pdia3) are the best-studied candidates for mediating these rapid responses to vitamin D metabolites. This paper provides an overview of the calcifediol-related mechanisms of action, which may help to better understand the vitamin D endocrine system and to identify new therapeutic targets that could be important for treating diseases closely associated with vitamin D deficiency.
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Affiliation(s)
- Simone Donati
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Gaia Palmini
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Cinzia Aurilia
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Irene Falsetti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Francesca Marini
- Fondazione Italiana Ricerca Sulle Malattie dell’Osso (FIRMO Onlus), 50129 Florence, Italy;
| | - Francesca Giusti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Teresa Iantomasi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy; (S.D.); (G.P.); (C.A.); (I.F.); (F.G.); (T.I.)
| | - Maria Luisa Brandi
- Fondazione Italiana Ricerca Sulle Malattie dell’Osso (FIRMO Onlus), 50129 Florence, Italy;
- Donatello Bone Clinic, Villa Donatello Hospital, 50019 Sesto Fiorentino, Italy
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Hanel A, Veldhuizen C, Carlberg C. Gene-Regulatory Potential of 25-Hydroxyvitamin D3 and D2. Front Nutr 2022; 9:910601. [PMID: 35911100 PMCID: PMC9330572 DOI: 10.3389/fnut.2022.910601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Human peripheral blood mononuclear cells (PBMCs) represent a highly responsive primary tissue that is composed of innate and adaptive immune cells. In this study, we compared modulation of the transcriptome of PBMCs by the vitamin D metabolites 25-hydroxyvitamin D3 (25(OH)D3), 25(OH)D2 and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). Saturating concentrations of 1,25(OH)2D3, 25(OH)D3 and 25(OH)D2 resulted after 24 h stimulation in a comparable number and identity of target genes, but below 250 nM 25(OH)D3 and 25(OH)D2 were largely insufficient to affect the transcriptome. The average EC50 values of 206 common target genes were 322 nM for 25(OH)D3 and 295 nM for 25(OH)D2 being some 600-fold higher than 0.48 nM for 1,25(OH)2D3. The type of target gene, such as primary/secondary, direct/indirect or up-/down-regulated, had no significant effect on vitamin D metabolite sensitivity, but individual genes could be classified into high, mid and lower responders. Since the 1α-hydroxylase CYP27B1 is very low expressed in PBMCs and early (4 and 8 h) transcriptome responses to 25(OH)D3 and 25(OH)D2 were as prominent as to 1,25(OH)2D3, both vitamin D metabolites may directly control gene expression. In conclusion, at supra-physiological concentrations 25(OH)D3 and 25(OH)D2 are equally potent in modulating the transcriptome of PBMCs possibly by directly activating the vitamin D receptor.
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Affiliation(s)
- Andrea Hanel
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | | | - Carsten Carlberg
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
- Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland
- *Correspondence: Carsten Carlberg
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Transcriptome-Wide Profile of 25-Hydroxyvitamin D 3 in Primary Immune Cells from Human Peripheral Blood. Nutrients 2021; 13:nu13114100. [PMID: 34836354 PMCID: PMC8624141 DOI: 10.3390/nu13114100] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/13/2021] [Accepted: 11/14/2021] [Indexed: 12/13/2022] Open
Abstract
Vitamin D3 is an essential micronutrient mediating pleiotropic effects in multiple tissues and cell types via its metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), which activates the transcription factor vitamin D receptor. In this study, we used peripheral blood mononuclear cells (PBMCs) obtained from five healthy adults and investigated transcriptome-wide, whether the precursor of 1,25(OH)2D3, 25-hydroxyvitamin D3 (25(OH)D3), has gene regulatory potential on its own. Applying thresholds of >2 in fold change of gene expression and <0.05 as a false discovery rate, in this ex vivo approach the maximal physiological concentration of 25(OH)D3 (250 nM (nmol/L)) none of the study participants had a significant effect on their PBMC transcriptome. In contrast, 1000 and 10,000 nM 25(OH)D3 regulated 398 and 477 genes, respectively, which is comparable to the 625 genes responding to 10 nM 1,25(OH)2D3. The majority of these genes displayed specificity to the tested individuals, but not to the vitamin D metabolite. Interestingly, the genes MYLIP (myosin regulatory light chain interacting protein) and ABCG1 (ATP binding cassette subfamily G member 1) showed to be specific targets of 10,000 nM 25(OH)D3. In conclusion, 100- and 1000-fold higher 25(OH)D3 concentrations than the reference 10 nM 1,25(OH)2D3 are able to affect the transcriptome of PBMCs with a profile comparable to that of 1,25(OH)2D3.
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Tuckey RC, Cheng CYS, Slominski AT. The serum vitamin D metabolome: What we know and what is still to discover. J Steroid Biochem Mol Biol 2019; 186:4-21. [PMID: 30205156 PMCID: PMC6342654 DOI: 10.1016/j.jsbmb.2018.09.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 09/04/2018] [Accepted: 09/04/2018] [Indexed: 01/08/2023]
Abstract
Vitamin D, referring to the two forms, D2 from the diet and D3 primarily derived from phototransformation in the skin, is a prohormone important in human health. The most hormonally active form, 1α,25-dihydroxyvitamin D (1α,25(OH)2D), formed from vitamin D via 25-hydroxyvitamin D (25(OH)D), is not only important for regulating calcium metabolism, but has many pleiotropic effects including regulation of the immune system and has anti-cancer properties. The major circulating form of vitamin D is 25(OH)D and both D2 and D3 forms are routinely measured by LC/MS/MS to assess vitamin D status, due to their relatively long half-lives and much higher concentrations compared to 1α,25(OH)2D. Inactivation of both 25(OH)D and 1α,25(OH)2D is catalyzed by CYP24A1 and 25-hydroxyvitamin D3 3-epimerase. Initial products from these enzymes acting on 25(OH)D3 are 24R,25(OH)2D3 and 3-epi-25(OH)D3, respectively, and both of these can also be measured routinely in some clinical laboratories to further document vitamin D status. With advances in LC/MS/MS and its increased availability, and with the help of studies with recombinant vitamin D-metabolizing enzymes, many other vitamin D metabolites have now been detected and in some cases quantitated, in human serum. CYP11A1 which catalyzes the first step in steroidogenesis, has been found to also act on vitamins D3 and D2 hydroxylating both at C20, but with some secondary metabolites produced by subsequent hydroxylations at other positions on the side chain. The major vitamin D3 metabolite, 20S-hydroxyvitamin D3 (20S(OH)D3), shows biological activity, often similar to 1α,25(OH)2D3 but without calcemic effects. Using standards produced enzymatically by purified CYP11A1 and characterized by NMR, many of these new metabolites have been detected in human serum, with semi-quantitative measurement of 20S(OH)D3 indicating it is present at comparable concentrations to 24R,25(OH)2D3 and 3-epi-25(OH)D3. Recently, vitamin D-related hydroxylumisterols derived from lumisterol3, a previtamin D3 photoproduct, have also been measured in human serum and displayed biological activity in initial in vitro studies. With the current extensive knowledge on the reactions and pathways of metabolism of vitamin D, especially those catalyzed by CYP24A1, CYP27A1, CYP27B1, CYP3A4 and CYP11A1, it is likely that many other of the resulting hydroxyvitamin D metabolites will be measured in human serum in the future, some contributing to a more detailed understanding of vitamin D status in health and disease.
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Affiliation(s)
- Robert C Tuckey
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia.
| | - Chloe Y S Cheng
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
| | - Andrzej T Slominski
- Department of Dermatology, University of Alabama at Birmingham, AL, 35294, USA; Comprehensive Cancer Center Cancer Chemoprevention Program, University of Alabama at Birmingham, AL, 35294, USA; VA Medical Center, Birmingham, AL, 35294, USA
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7
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Abstract
Hypercalcemia 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.
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Affiliation(s)
- Peter J Tebben
- Divisions of Endocrinology (P.J.T., R.K.) and Nephrology and Hypertension (R.K.), and Departments of Pediatric and Adolescent Medicine (P.J.T.), Internal Medicine (P.J.T., R.K.), Laboratory Medicine and Pathology (R.J.S.), and Biochemistry in Molecular Biology (R.K.), Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Ravinder J Singh
- Divisions of Endocrinology (P.J.T., R.K.) and Nephrology and Hypertension (R.K.), and Departments of Pediatric and Adolescent Medicine (P.J.T.), Internal Medicine (P.J.T., R.K.), Laboratory Medicine and Pathology (R.J.S.), and Biochemistry in Molecular Biology (R.K.), Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Rajiv Kumar
- Divisions of Endocrinology (P.J.T., R.K.) and Nephrology and Hypertension (R.K.), and Departments of Pediatric and Adolescent Medicine (P.J.T.), Internal Medicine (P.J.T., R.K.), Laboratory Medicine and Pathology (R.J.S.), and Biochemistry in Molecular Biology (R.K.), Mayo Clinic College of Medicine, Rochester, Minnesota 55905
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Chiellini G, Grzywacz P, Plum LA, Barycki R, Clagett-Dame M, DeLuca HF. Synthesis and biological properties of 2-methylene-19-nor-25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactones--weak agonists. Bioorg Med Chem 2008; 16:8563-73. [PMID: 18722130 DOI: 10.1016/j.bmc.2008.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 01/25/2023]
Abstract
In a continuing effort to explore the 2-methylene-1alpha-hydroxy-19-norvitamin D(3) class of pharmacologically important vitamin D compounds, two novel 2-methylene-19-nor-25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactones, GC-3 and HLV, were synthesized and biologically tested. Based on reports of similarly structured molecules, it was hypothesized that these compounds might act as antagonists, at least in vitro. The pathway designed to synthesize these compounds was based on two key steps: first, the Lythgoe-type Wittig-Horner coupling of Windaus-Grundmann-type ketone 18, with phosphine oxide 15, followed, later in the synthesis, by the Zn-mediated Reformatsky-type allylation of aldehyde 20 with methylbromomethylacrylate 8. Our biological data show that neither compound has antagonistic activity but acts as weak agonists in vitro and in vivo.
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Affiliation(s)
- Grazia Chiellini
- Department of Biochemistry, College of Agriculture and Life Sciences, 433 Babcock Drive, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
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Affiliation(s)
- M J Beckman
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706, USA
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Bishop JE, Collins ED, Okamura WH, Norman AW. Profile of ligand specificity of the vitamin D binding protein for 1 alpha,25-dihydroxyvitamin D3 and its analogs. J Bone Miner Res 1994; 9:1277-88. [PMID: 7976510 DOI: 10.1002/jbmr.5650090818] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The profile of structural preference for the ligand binding domain of the human vitamin D binding protein (DBP) was determined by steroid competition assay of 71 analogs of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]. The following categories of structural modification were evaluated [values represent fold change; R = reduction, I = increase in binding to the DBP from the reference 1 alpha, 25(OH)2D3]: (1) deletion in the A ring of the 1 alpha-hydroxyl-(20-1600I); (2) conversion of the triene system to the previtamin form (6-40R); (3) addition of substituents to carbon 11 of the C ring (4-14R); (4) inversion of the C/D ring junction (8-20R); (5) unsaturation of the D ring (16-ene; 4-140R); (6) replacement of hydrogen with deuterium atoms (no effect); alteration of the side chain by (7) adding or deleting carbon atoms (5-12R); (8) addition of fluorines (0.2-10R); (9) presence of unsaturation (22-ene, 0-5R; 23-ene, 3R-10I; 23-yne, 5-20R); (10) addition of hydroxyls (2-100R); and (11) addition of an aromatic ring (0-20I). Thus the DBP ligand binding domain could tolerate only modest changes to the structure of 1 alpha,25(OH)2D3 without a reduction in binding of the analog. The increases in binding seen in the aromatic side chain and with a triple bond at carbon-23 may be indicative of a preferred conformation of the flexible 1 alpha, 25(OH)2D3 side chain. In addition, a comparison was made of the DBP ligand binding domain with that of the human HL-60 cell 1 alpha, 25(OH)2D3 nuclear receptor. Both ligand binding domains could equivalently accommodate to the presence of (1) a side-chain cyclopropyl group, (2) 22-ene or 23-yne, (3) lengthening the side chain by two carbons, (4) presence of four to six fluorine atoms, (5) substitution of an oxygen for carbon 22, and (6) presence of a 22-[m-(dimethylhydroxymethyl)phenyl] aromatic group in the side chain. The DPB could tolerate better than the HL-60 cell receptor the presence of a 22-(p-hydroxyphenyl) aromatic group in the side chain and the absence of the 1 alpha-hydroxyl. In contrast, the HL-60 cell receptor could tolerate better than the DBP the following structural modifications: presence of a 16-ene, or 16-ene plus 23-yne unsaturation, and presence of an 11 beta-hydroxyl.
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Affiliation(s)
- J E Bishop
- Department of Biochemistry, University of California, Riverside
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Norman AW. The avian as an animal model for the study of the vitamin D endocrine system. THE JOURNAL OF EXPERIMENTAL ZOOLOGY. SUPPLEMENT : PUBLISHED UNDER AUSPICES OF THE AMERICAN SOCIETY OF ZOOLOGISTS AND THE DIVISION OF COMPARATIVE PHYSIOLOGY AND BIOCHEMISTRY 1990; 4:37-45. [PMID: 1974802 DOI: 10.1002/jez.1402560408] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This paper presents a summary of experimental studies which utilized the White Leghorn cockerel, Gallus domesticus, as a suitable avian model for a detailed analysis of the mode of action of the seco-steroid vitamin D. It is now apparent that there exists a complex endocrine system which coordinates the metabolism of the parent vitamin D into a family of over 30 metabolites; the principal metabolites are 1,25(OH)2D3 and 24R,25(OH)2D3, which together orchestrate the spectrum of biological responses attributable to vitamin D. Key advances in elucidation of the scope of vitamin D endocrine system include the tissue distribution of both its steroid receptor and its gene-induced product, a 28,000 dalton calcium binding protein, termed calbindin-D28k. To date no less than 23 tissues have been found to have specific 1,25(OH)2D3 receptors; of these at least 10 were identified in avian studies. Similarly, nine avian tissues have been found to express the vitamin D-induced calcium binding protein, calbindin-D28k. These observations collectively demonstrate both the broad scope of the vitamin D endocrine system and the appropriateness of using avians as valid models for vitamin D endocrine research which has applicability and validity for mammals, including man.
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Affiliation(s)
- A W Norman
- Division of Biomedical Sciences, University of California, Riverside 92521
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Vanham G, Van Baelen H, Tan BK, Bouillon R. The effect of vitamin D analogs and of vitamin D-binding protein on lymphocyte proliferation. JOURNAL OF STEROID BIOCHEMISTRY 1988; 29:381-6. [PMID: 3374126 DOI: 10.1016/0022-4731(88)90246-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In the absence of vitamin D-binding protein (DBP), 1,25-(OH)2D3 at 10(-12) M significantly inhibited the [3H]thymidine incorporation in human lymphocytes during mixed lymphocyte cultures (MLC) or after phyto-hemaglutinin (PHA) stimulation. In the presence of a physiological concentration of DBP (5 x 10(-6) M), the concentration of 1,25-(OH)2D3 required for inhibition was 10(-10) M (for PHA-cultures) and 10(-9) M (for MLC). Several vitamin D analogs were compared for their inhibitory action on PHA stimulation. In the absence of DBP, the concentration necessary for 50% inhibition of [3H]thymidine incorporation ranged from 10(-12) M [1,25-(OH)2D3 and 24,24-F2-1,25-(OH)2D3], over 10(-10) M [1,24R, 25-(OH)3D3; 1,25S, 26-(OH)3D3 and 26,27-F6-1,25-(OH)2D3] and 10(-8) M [25 OHD3 and 24,25-(OH)2D3] to 10(-6) M [calcitriol-lactone]. This rank order correlates with the binding affinity of the various analogs to the cytoplasmic 1,25-(OH)2D3-receptor. DBP counteracted the inhibitory effect of all analogs and the degree of counteraction was directly proportional to the binding affinity between DBP and the vitamin D analog. DBP thus decreased the in vitro inhibitory action of 1,25-(OH)2D3 and its analogs on lymphocyte proliferation. Of all analogs tested, only 1,25-(OH)2D3 had a significant effect at a physiological concentration.
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Affiliation(s)
- G Vanham
- Laboratorium voor Experimentele Geneeskunde en Endocrinologie, Onderwijs en Navorsing, Leuven, Belgium
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Ikekawa N. Structures and biological activities of vitamin D metabolites and their analogs. Med Res Rev 1987; 7:333-66. [PMID: 3306217 DOI: 10.1002/med.2610070304] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Wilhelm F, Norman AW. Biochemical characterization of positive cooperativity in the binding of 1 alpha, 25-dihydroxyvitamin D3 to its chick intestinal chromatin receptor. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39216-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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