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Huang A, Binmahfouz L, Hancock DP, Anderson PH, Ward DT, Conigrave AD. Calcium-Sensing Receptors Control CYP27B1-Luciferase Expression: Transcriptional and Posttranscriptional Mechanisms. J Endocr Soc 2021; 5:bvab057. [PMID: 34337274 PMCID: PMC8317635 DOI: 10.1210/jendso/bvab057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Indexed: 12/19/2022] Open
Abstract
25-hydroxyvitamin D 1α-hydroxylase (encoded by CYP27B1), which catalyzes the synthesis of 1,25-dihydroxyvitamin D3, is subject to negative or positive modulation by extracellular Ca2+ (Ca2+o) depending on the tissue. However, the Ca2+ sensors and underlying mechanisms are unidentified. We tested whether calcium-sensing receptors (CaSRs) mediate Ca2+o-dependent control of 1α-hydroxylase using HEK-293 cells stably expressing the CaSR (HEK-CaSR cells). In HEK-CaSR cells, but not control HEK-293 cells, cotransfected with reporter genes for CYP27B1-Photinus pyralis (firefly) luciferase and control Renilla luciferase, an increase in Ca2+o from 0.5mM to 3.0mM induced a 2- to 3-fold increase in firefly luciferase activity as well as mRNA and protein levels. Surprisingly, firefly luciferase was specifically suppressed at Ca2+o ≥ 5.0mM, demonstrating biphasic Ca2+o control. Both phases were mediated by CaSRs as revealed by positive and negative modulators. However, Ca2+o induced simple monotonic increases in firefly luciferase and endogenous CYP27B1 mRNA levels, indicating that the inhibitory effect of high Ca2+o was posttranscriptional. Studies with inhibitors and the CaSR C-terminal mutant T888A identified roles for protein kinase C (PKC), phosphorylation of T888, and extracellular regulated protein kinase (ERK)1/2 in high Ca2+o-dependent suppression of firefly luciferase. Blockade of both PKC and ERK1/2 abolished Ca2+o-stimulated firefly luciferase, demonstrating that either PKC or ERK1/2 is sufficient to stimulate the CYP27B1 promoter. A key CCAAT box (−74 bp to −68 bp), which is regulated downstream of PKC and ERK1/2, was required for both basal transcription and Ca2+o-mediated transcriptional upregulation. The CaSR mediates Ca2+o-dependent transcriptional upregulation of 1α-hydroxylase and an additional CaSR-mediated mechanism is identified by which Ca2+o can promote luciferase and possibly 1α-hydroxylase breakdown.
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Affiliation(s)
- Alice Huang
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
| | - Lenah Binmahfouz
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Dale P Hancock
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
| | - Paul H Anderson
- Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, SA, 5001, Australia
| | - Donald T Ward
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Arthur D Conigrave
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
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2
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Martinelli RP, Rodriguez JM, Daurelio LD, Esteban L. In silico identification of novel transcription factors associated with CYP27B1 transcriptional regulation in LPS-challenged mononuclear phagocytes. J Steroid Biochem Mol Biol 2020; 199:105590. [PMID: 32001361 DOI: 10.1016/j.jsbmb.2020.105590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 12/13/2019] [Accepted: 01/13/2020] [Indexed: 01/08/2023]
Abstract
Renal and extrarenal production of the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), is catalyzed by CYP27B1, an enzyme also called 1-α-hydroxylase. The overproduction of 1,25(OH)2D has been described in granulomatous diseases. High circulating concentrations of 1,25(OH)2D can lead to hypercalcemia. The aim of this work was to characterize the transcriptional regulation of CYP27B1 in human mononuclear phagocytes exposed to LPS due to its relevance to understanding the hypercalcemia and ectopic calcifications associated with chronic inflammatory diseases such as tuberculosis and other granulomatous diseases. The human CYP27B1 promoter analysis identified binding sites for published TF, SNPs, novel putative TFBS and conserved sites compared to mice. Then, using microarray data, a meta-analysis was performed to obtain a global view of the gene expression in LPS-challenged dendritic cells, monocytes and macrophages. Finally, two experiments, GSE40885 and time series GSE19765, were analyzed in-depth using differential expression analysis which permitted the identification of TF co-expressed with CYP27B1. This work allowed us to formulate a CYP27B1 transcriptional regulation model for LPS-challenged monocytes/macrophages. The importance of two TF families, NFKB and CEBPB, was confirmed. Data also suggests that PLAGL2 and STAT4 which are novel TF could participate in the CYP27B1 transcriptional regulation in cells exposed to LPS. These TF, in turn, would be interacting with regions that present polymorphisms in the general population which might explain the pathological phenotypes associated with altered vitamin D metabolism.
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Affiliation(s)
- Romina P Martinelli
- Departamento de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Cátedra de Genética Humana, Facultad de Medicina, Universidad Abierta Interamericana, Rosario, Santa Fe, Argentina.
| | - Julia M Rodriguez
- Departamento de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Lucas D Daurelio
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Laboratorio de Investigaciones en Fisiología y Biología Molecular Vegetal (LIFiBVe), Cátedra de Fisiología Vegetal, Facultad de Ciencias Agrarias, Universidad Nacional del Litoral, Esperanza, Santa Fe, Argentina.
| | - Luis Esteban
- Departamento de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina.
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3
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Wilkens MR, Elfers K, Schmicke M, Breves G, Muscher-Banse AS. Dietary nitrogen and calcium modulate CYP27B1 expression in young goats. Domest Anim Endocrinol 2018; 64:70-76. [PMID: 29754009 DOI: 10.1016/j.domaniend.2018.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 03/05/2018] [Accepted: 03/27/2018] [Indexed: 11/28/2022]
Abstract
In livestock, feeding a reduced nitrogen (N) diet is favored for economic and ecological reasons. Ruminants cope more easily with a reduced N diet than monogastric species. However, changes in mineral homeostasis such as a reduction in 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) concentrations, calcium (Ca), and IGF1 levels were observed in goats kept on a reduced N diet. The decrease in 1,25-(OH)2D3 occurred even during a simultaneous reduction in dietary N and Ca, whereas a solitary Ca reduction stimulated 1,25-(OH)2D3 synthesis. The aim of the present study was to examine the effects of N- and/or Ca-reduced diets on the expression of 24-hydroxylase (CYP24A1), 1-alpha-hydroxylase (CYP27B1), vitamin D receptor (VDR), retinoid X receptor alpha (RXRα), IGF1 receptor (IGF1R), Klotho, and fibroblast growth factor receptor 1c (FGFR1c) in kidneys of young goats. Four groups were kept on a control diet, an N-reduced diet, a Ca-reduced diet or an N- and a Ca-reduced diet. Renal expression of CYP24A1 was not affected, whereas CYP27B1 expression was significantly diminished in the N-reduced diet fed goats (P < 0.05) and significantly elevated with the Ca reduction (P < 0.001). The VDR expression was not modified, whereas RXRα (P < 0.05) and Klotho expression (P < 0.001) were stimulated during Ca reduction. The IGF1R (P < 0.05) and FGFR1c (P < 0.05) expression were enhanced with the N reduction. From these data, it can be concluded that the downregulation of renal CYP27B1 expression observed with dietary N reduction is probably mediated by a complex interaction between the somatotropic axis and the Klotho/FGF signaling pathway in young goats.
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MESH Headings
- 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/genetics
- 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/metabolism
- Animal Feed/analysis
- Animal Nutritional Physiological Phenomena
- Animals
- Calcitriol/blood
- Calcium, Dietary/administration & dosage
- Calcium, Dietary/pharmacology
- Diet/veterinary
- Gene Expression Regulation/drug effects
- Glucuronidase/genetics
- Glucuronidase/metabolism
- Goats/physiology
- Kidney/enzymology
- Kidney/metabolism
- Klotho Proteins
- Male
- Nitrogen/administration & dosage
- Receptor, Fibroblast Growth Factor, Type 1/genetics
- Receptor, Fibroblast Growth Factor, Type 1/metabolism
- Receptors, Calcitriol/genetics
- Receptors, Calcitriol/metabolism
- Receptors, Somatomedin/genetics
- Receptors, Somatomedin/metabolism
- Retinoid X Receptor alpha/genetics
- Retinoid X Receptor alpha/metabolism
- Vitamin D3 24-Hydroxylase/genetics
- Vitamin D3 24-Hydroxylase/metabolism
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Affiliation(s)
- M R Wilkens
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, D-30173 Hannover, Germany
| | - K Elfers
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, D-30173 Hannover, Germany
| | - M Schmicke
- Clinic for Cattle, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173 Hannover, Germany
| | - G Breves
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, D-30173 Hannover, Germany
| | - A S Muscher-Banse
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, D-30173 Hannover, Germany.
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4
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Bikle DD, Patzek S, Wang Y. Physiologic and pathophysiologic roles of extra renal CYP27b1: Case report and review. Bone Rep 2018; 8:255-267. [PMID: 29963603 PMCID: PMC6021194 DOI: 10.1016/j.bonr.2018.02.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 02/23/2018] [Indexed: 01/13/2023] Open
Abstract
Although the kidney was initially thought to be the sole organ responsible for the production of 1,25(OH)2D via the enzyme CYP27b1, it is now appreciated that the expression of CYP27b1 in tissues other than the kidney is wide spread. However, the kidney is the major source for circulating 1,25(OH)2D. Only in certain granulomatous diseases such as sarcoidosis does the extra renal tissue produce sufficient 1,25(OH)2D to contribute to the circulating levels, generally associated with hypercalcemia, as illustrated by the case report preceding the review. Therefore the expression of CYP27b1 outside the kidney under normal circumstances begs the question why, and in particular whether the extra renal production of 1,25(OH)2D has physiologic importance. In this chapter this question will be discussed. First we discuss the sites for extra renal 1,25(OH)2D production. This is followed by a discussion of the regulation of CYP27b1 expression and activity in extra renal tissues, pointing out that such regulation is tissue specific and different from that of CYP27b1 in the kidney. Finally the physiologic significance of extra renal 1,25(OH)2D3 production is examined, with special focus on the role of CYP27b1 in regulation of cellular proliferation and differentiation, hormone secretion, and immune function. At this point the data do not clearly demonstrate an essential role for CYP27b1 expression in any tissue outside the kidney, but several examples pointing in this direction are provided. With the availability of the mouse enabling tissue specific deletion of CYP27b1, the role of extra renal CYP27b1 expression in normal and pathologic states can now be addressed definitively.
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Affiliation(s)
- Daniel D Bikle
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Sophie Patzek
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Yongmei Wang
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
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5
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Abstract
PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.
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Affiliation(s)
- Syed Jalal Khundmiri
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
| | - Rebecca D. Murray
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
| | - Eleanor Lederer
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
- Robley Rex VA Medical Center, University of Louisville, Louisville, Kentucky, USA
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6
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Chanakul A, Zhang MYH, Louw A, Armbrecht HJ, Miller WL, Portale AA, Perwad F. FGF-23 regulates CYP27B1 transcription in the kidney and in extra-renal tissues. PLoS One 2013; 8:e72816. [PMID: 24019880 PMCID: PMC3760837 DOI: 10.1371/journal.pone.0072816] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 07/21/2013] [Indexed: 12/18/2022] Open
Abstract
The mitochondrial enzyme 25-hydroxyvitamin D 1α-hydroxylase, which is encoded by the CYP27B1 gene, converts 25OHD to the biological active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D). Renal 1α-hydroxylase activity is the principal determinant of the circulating 1,25(OH)2D concentration and enzyme activity is tightly regulated by several factors. Fibroblast growth factor-23 (FGF-23) decreases serum 1,25(OH)2D concentrations by suppressing CYP27B1 mRNA abundance in mice. In extra-renal tissues, 1α-hydroxylase is responsible for local 1,25(OH)2D synthesis, which has important paracrine actions, but whether FGF-23 regulates CYP27B1 gene expression in extra-renal tissues is unknown. We sought to determine whether FGF-23 regulates CYP27B1 transcription in the kidney and whether extra-renal tissues are target sites for FGF-23-induced suppression of CYP27B1. In HEK293 cells transfected with the human CYP27B1 promoter, FGF-23 suppressed promoter activity by 70%, and the suppressive effect was blocked by CI-1040, a specific inhibitor of extracellular signal regulated kinase 1/2. To examine CYP27B1 transcriptional activity in vivo, we crossed fgf-23 null mice with mice bearing the CYP27B1 promoter-driven luciferase transgene (1α-Luc). In the kidney of FGF-23 null/1α-Luc mice, CYP27B1 promoter activity was increased by 3-fold compared to that in wild-type/1α-Luc mice. Intraperitoneal injection of FGF-23 suppressed renal CYP27B1 promoter activity and protein expression by 26% and 60% respectively, and the suppressive effect was blocked by PD0325901, an ERK1/2 inhibitor. These findings provide evidence that FGF-23 suppresses CYP27B1 transcription in the kidney. Furthermore, we demonstrate that in FGF-23 null/1α-Luc mice, CYP27B1 promoter activity and mRNA abundance are increased in several extra-renal sites. In the heart of FGF-23 null/1α-Luc mice, CYP27B1 promoter activity and mRNA were 2- and 5-fold higher, respectively, than in control mice. We also observed a 3- to 10-fold increase in CYP27B1 mRNA abundance in the lung, spleen, aorta and testis of FGF-23 null/1α-Luc mice. Thus, we have identified novel extra-renal target sites for FGF-23-mediated regulation of CYP27B1.
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Affiliation(s)
- Ankanee Chanakul
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Martin Y. H. Zhang
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Andrew Louw
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Harvey J. Armbrecht
- Geriatric Research, Education, and Clinical Center, St. Louis Veterans Affairs Medical Center, St. Louis, Missouri, United States of America
| | - Walter L. Miller
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Anthony A. Portale
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
| | - Farzana Perwad
- Department of Pediatrics, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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7
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Kozai M, Yamamoto H, Ishiguro M, Harada N, Masuda M, Kagawa T, Takei Y, Otani A, Nakahashi O, Ikeda S, Taketani Y, Takeyama KI, Kato S, Takeda E. Thyroid hormones decrease plasma 1α,25-dihydroxyvitamin D levels through transcriptional repression of the renal 25-hydroxyvitamin D3 1α-hydroxylase gene (CYP27B1). Endocrinology 2013; 154:609-22. [PMID: 23307792 DOI: 10.1210/en.2012-1647] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The primary determinant of circulating 1α,25-dihydroxyvitamin D (1,25[OH](2)D) levels is the activity of 25-hydroxyvitamin D-1α-hydroxylase (cytochrome P450 27B1 [CYP27B1]) in the kidney. Hyperthyroid patients have been reported to have low levels of plasma 1,25(OH)(2)D. However, the detailed mechanism of thyroid hormone action on vitamin D metabolism is still poorly understood. The present study determined whether renal CYP27B1 gene expression was negatively regulated by thyroid hormones. T(3)-induced hyperthyroid mice showed marked decreases in plasma 1,25(OH)(2)D levels and in renal expression of CYP27B1 mRNA but no changes in plasma concentrations of calcium, PTH, or fibroblast growth factor-23. In addition, we observed that T(3) administration significantly decreased plasma 1,25(OH)(2)D and renal CYP27B1 mRNA levels that were increased by low-calcium or low-phosphorus diets and induced hypocalcemia in mice fed a low-calcium diet. Promoter analysis revealed that T(3) decreases the basal transcriptional activity of the CYP27B1 gene through thyroid hormone receptors (TRα and TRβ1) and the retinoid X receptor α (RXRα) in renal proximal tubular cells. Interestingly, we identified an everted repeat negative thyroid hormone response element (1α-nTRE) overlapping the sterol regulatory element (1α-SRE) and the TATA-box -50 to -20 base pairs from the human CYP27B1 gene transcription start site. Finally, we established that CYP27B1 gene transcription is positively regulated by SRE-binding proteins and that a T(3)-bound TRβ1/RXRα heterodimer inhibits SRE-binding protein-1c-induced transcriptional activity through the 1α-nTRE. These results suggest that transcriptional repression of the CYP27B1 gene by T(3)-bound TRs/RXRα, acting through the 1α-nTRE, results in decreased renal CYP27B1 expression and plasma 1,25(OH)(2)D levels.
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Affiliation(s)
- Mina Kozai
- Department of Clinical Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima City, 770-8503, Japan
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8
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Anderson PH, Turner AG, Morris HA. Vitamin D actions to regulate calcium and skeletal homeostasis. Clin Biochem 2012; 45:880-6. [PMID: 22414785 DOI: 10.1016/j.clinbiochem.2012.02.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/22/2022]
Abstract
The endocrine action of plasma 1,25-dihydroxyvitamin D plays a key role in the regulation of plasma calcium and phosphate homeostasis with activities on the intestine, kidney and bone. A current, controversial question is whether vitamin D exerts direct actions on bone cells to regulate bone mineral homeostasis. Results from clinical, rodent model and in vitro studies on human bone cells provide an impressive body of data to support this proposal particularly at the level of serum 25-hydroxyvitamin D status. Each of the major bone cell types is capable of metabolising vitamin D to the active metabolite, 1,25-dihydroxyvitamin D. Thus under conditions when bone tissue synthesis of 1,25-dihydroxyvitamin D is optimal, vitamin D activity enhances bone mineral status. Dietary calcium and phosphate intakes are the critical environmental cues together with vitamin D status to determine whether 1,25-dihydroxyvitamin D exerts an anabolic or catabolic action on bone mineral status.
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Affiliation(s)
- Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, and Chemical Pathology Directorate, SA Pathology, Frome Road, Adelaide 5000 SA, Australia
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9
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Anderson PH, Atkins GJ, Turner AG, Kogawa M, Findlay DM, Morris HA. Vitamin D metabolism within bone cells: effects on bone structure and strength. Mol Cell Endocrinol 2011; 347:42-7. [PMID: 21664230 DOI: 10.1016/j.mce.2011.05.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/04/2011] [Accepted: 05/09/2011] [Indexed: 11/16/2022]
Abstract
The endocrine activity of 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) contributes to maintaining plasma calcium and phosphate homeostasis through actions on the intestine, kidney and bone. A significant body of evidence has been published over the last 10 years indicating that all major bone cells have the capacity to metabolise 25-hydroxyvitamin D (25(OH)D(3)) to 1,25(OH)(2)D(3), which in turn exerts autocrine/paracrine actions to regulate bone cell proliferation and maturation as well as bone mineralisation and resorption. In vivo and in vitro studies indicate that these autocrine/paracrine activities of 1,25(OH)(2)D(3) in bone tissue contribute to maintaining bone mineral homeostasis and enhancing skeletal health.
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Affiliation(s)
- Paul H Anderson
- Endocrine Bone Research Laboratory, Chemical Pathology, SA Pathology, Adelaide, SA 5000, Australia
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10
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White JH. Regulation of intracrine production of 1,25-dihydroxyvitamin D and its role in innate immune defense against infection. Arch Biochem Biophys 2011; 523:58-63. [PMID: 22107948 DOI: 10.1016/j.abb.2011.11.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 11/03/2011] [Indexed: 12/31/2022]
Abstract
Vitamin D was discovered as the cure for nutritional rickets. Classically, hormonal 1,25-dihydroxyvitamin D (1,25D), produced in the kidney by CYP27B1-catalyzed 1α-hydroxylation from its circulating 25-hydroxy precursor, has been considered to function as a critical endocrine regulator of calcium homeostasis. However, our appreciation of vitamin D metabolism and physiological function has evolved dramatically in recent years. First, vitamin D is now recognized as a pleiotropic regulator of human physiology, with emerging roles in cancer chemoprevention, cardio-protection, and, in particular, regulation of immune system functions. Moreover, CYP27B1 is very widely expressed, and evidence is rapidly accumulating that local CYP27B1-catalyzed production of 1,25D, controlled by tissue-specific signals, is critical for its physiological actions. Nowhere is this more apparent than in the innate immune system, where recent studies have shown that CYP27B1 expression is under control of several immune signaling pathways, and that signaling by 1,25D in macrophages and dendritic cells is critical for innate immune responses to infection. This review will describe our current knowledge of the signaling pathways that lead to 1,25D production in the immune system and the downstream signaling events it controls in response to pathogen recognition.
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Affiliation(s)
- John H White
- Department of Physiology, McIntyre Bldg., Rm. 1112, 3655 Drummond St., Montreal, Qc, Canada H3G 1Y6.
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11
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Abstract
Fundamental to understanding the way in which perturbations in the vitamin D endocrine system can affect human health is an appreciation of the steps involved in the production of the well-recognized active hormonal form, 1,25-dihydroxyvitamin D(3). Thus this paper focuses first on the nature and regulation of the two enzymes responsible for the production of 1,25-dihydroxyvitamin D(3), the 25-hydroxylase in the liver and the 1α-hydroxylase in the kidney. The most important regulators of the 1α-hydroxylase in the kidney are 1,25-dihydroxyvitamin D(3) itself, parathyroid hormone and FGF23. The extent and importance of extra-renal, 1,25-dihydroxyvitamin D(3) synthesis is then considered. Finally the features of the 24R-hydroxylase, which produces 24R,25-dihydroxyvitamin D(3) in the kidney and is induced by and inactivated, 1,25-dihydroxyvitamin D(3)in target cells are described.
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Affiliation(s)
- Helen L Henry
- Department of Biochemistry, University of California, Riverside, CA 92521, USA.
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12
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Clifton-Bligh RJ, Nguyen TV, Au A, Bullock M, Cameron I, Cumming R, Chen JS, March LM, Seibel MJ, Sambrook PN. Contribution of a common variant in the promoter of the 1-α-hydroxylase gene (CYP27B1) to fracture risk in the elderly. Calcif Tissue Int 2011; 88:109-16. [PMID: 21107545 PMCID: PMC3030947 DOI: 10.1007/s00223-010-9434-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 09/22/2010] [Indexed: 01/01/2023]
Abstract
CYP27B1 encodes mitochondrial 1α-hydroxylase, which converts 25-hydroxyvitamin D to its active 1,25-dihydroxylated metabolite. We tested the hypothesis that common variants in the CYP27B1 promoter are associated with fracture risk. The study was designed as a population-based genetic association study, which involved 153 men and 596 women aged 65-101 years, who had been followed for 2.2 years (range 0.1-5.5) between 1999 and 2006. During the follow-up period, the incidence of fragility fractures was ascertained. Bone ultrasound attenuation (BUA) was measured in all individuals, as were serum 25-hydroxyvitamin D and PTH concentrations; 86% subjects had vitamin D insufficiency. Genotypes were determined for the -1260C>A (rs10877012) and +2838T>C (rs4646536) CYP27B1 polymorphisms. A reporter gene assay was used to assess functional expression of the -1260C>A CYP27B1 variants. The association between genotypes and fracture risk was analyzed by Cox's proportional hazards model. We found that genotypic distribution of CYP27B1 -1260 and CYP27B1 +2838 polymorphisms was consistent with the Hardy-Weinberg equilibrium law. The two polymorphisms were in high linkage disequilibrium, with D' = 0.96 and r² = 0.94. Each C allele of the CYP27B1 -1260 polymorphism was associated with increased risk of fracture (hazard ratio = 1.34, 95% CI 1.03-1.73), after adjustment for age, sex, number of falls, and BUA. In transient transfection studies, a reporter gene downstream of the -1260(A)-containing promoter was more highly expressed than that containing the C allele. These data suggest that a common but functional variation within the CYP27B1 promoter gene is associated with fracture risk in the elderly.
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Affiliation(s)
- Roderick J Clifton-Bligh
- Northern Metabolic Bone Research Unit, Royal North Shore Hospital, St. Leonards, NSW, Australia.
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13
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Turner AG, Dwivedi PP, Anderson PH, May BK, Morris HA. Regulation of the 5'-flanking region of the human CYP27B1 gene in osteoblast cells. Mol Cell Endocrinol 2009; 311:55-61. [PMID: 19524013 DOI: 10.1016/j.mce.2009.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 04/20/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
Abstract
Synthesis of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) is catalysed by the enzyme 25-hydroxyvitamin D(3)-1alpha-hydroxylase (CYP27B1). Regulation of CYP27B1 gene expression is poorly understood, particularly in non-renal tissues including bone where 1,25(OH)(2)D(3) is hypothesised to serve autocrine/paracrine roles. Transient transfection of ROS 17/2.8 osteoblast-like cells with reporter gene constructs containing deletions of the 5'-flanking region of the human CYP27B1 gene revealed a proximal promoter, enhancer region and strong upstream repressive region. Putative CCAAT and GC boxes, as well as Ets protein binding sites were shown to contribute to promoter and enhancer activities respectively in common with kidney and prostate cells. Inhibition of basal expression was largely attributed to a palindrome 5'-GTCTCAGAC-3' (-1015/-1007bp) that contains two putative canonical Smad binding elements. We conclude that repression of CYP27B1 gene expression may be a common event but the novel inhibitory elements we have identified may be unique to osteoblasts.
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Affiliation(s)
- A G Turner
- Department of Medicine, Austin Health, University of Melbourne, Australia.
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14
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15
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Zhong Y, Armbrecht HJ, Christakos S. Calcitonin, a regulator of the 25-hydroxyvitamin D3 1alpha-hydroxylase gene. J Biol Chem 2009; 284:11059-69. [PMID: 19261615 DOI: 10.1074/jbc.m806561200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Although parathyroid hormone (PTH) induces 25-hydroxyvitamin D(3) (25(OH)D(3)) 1alpha-hydroxylase (1alpha(OH)ase) under hypocalcemic conditions, previous studies showed that calcitonin, not PTH, has an important role in the maintenance of serum 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) under normocalcemic conditions. In this study we report that 1alpha(OH)ase transcription is strongly induced by calcitonin in kidney cells and indicate mechanisms that underlie this regulation. The transcription factor C/EBPbeta is up-regulated by calcitonin in kidney cells and results in a significant enhancement of calcitonin induction of 1alpha(OH)ase transcription and protein expression. Mutation constructs of the 1alpha(OH)ase promoter demonstrate the importance of the C/EBPbeta binding site at -79/-73 for activation of the 1alpha(OH)ase promoter by calcitonin. The SWI/SNF chromatin remodeling complex was found to cooperate with calcitonin in the regulation of 1alpha(OH)ase. Chromatin immunoprecipitation analysis showed that calcitonin recruits C/EBPbeta to the 1alpha(OH)ase promoter, and Re-chromatin immunoprecipitation analysis (sequential chromatin immunoprecipitations using different antibodies) showed that C/EBPbeta and BRG1, an ATPase that is a component of the SWI/SNF complex, bind simultaneously to the 1alpha(OH)ase promoter. These findings are the first to address the dynamics between calcitonin, C/EBPbeta, and SWI/SNF in the regulation of 1alpha(OH)ase and provide a mechanism, for the first time, for calcitonin induction of 1alpha(OH)ase. Because plasma calcitonin as well as 1,25(OH)(2)D(3) have been reported to be increased during pregnancy and lactation and in early development, these findings suggest a mechanism that may account, at least in part, for the increase in plasma 1,25(OH)(2)D(3) during these times of increased calcium requirement.
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Affiliation(s)
- Yan Zhong
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA
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16
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van Etten E, Stoffels K, Gysemans C, Mathieu C, Overbergh L. Regulation of vitamin D homeostasis: implications for the immune system. Nutr Rev 2009; 66:S125-34. [PMID: 18844839 DOI: 10.1111/j.1753-4887.2008.00096.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Vitamin D homeostasis in the immune system is the focus of this review. The production of both the activating (25- and 1alpha-hydroxylase) and the metabolizing (24-hydroxylase) enzymes by cells of the immune system itself, indicates that 1,25(OH)(2)D(3) can be produced locally in immune reaction sites. Moreover, the strict regulation of these enzymes by immune signals is highly suggestive for an autocrine/paracrine role in the immune system, and opens new treatment possibilities.
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Affiliation(s)
- Evelyne van Etten
- The Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Katholieke Universiteit Leuven , Leuven, Belgium
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17
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Solomon SS, Majumdar G, Martinez-Hernandez A, Raghow R. A critical role of Sp1 transcription factor in regulating gene expression in response to insulin and other hormones. Life Sci 2008; 83:305-12. [PMID: 18664368 DOI: 10.1016/j.lfs.2008.06.024] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 06/16/2008] [Accepted: 06/19/2008] [Indexed: 02/02/2023]
Abstract
Specificity protein 1 (Sp1) belongs to a family of ubiquitously expressed, C(2)H(2)-type zinc finger-containing DNA binding proteins that activate or repress transcription of many genes in response to physiological and pathological stimuli. There is emerging evidence to indicate that in addition to functioning as 'housekeeping' transcription factors, members of Sp family may be key mediators of gene expression induced by insulin and other hormones. The founding member of the family, Sp1, by virtue of its multi-domain organization, potential for posttranslational modifications and interactions with numerous transcription factors, represents an ideal mediator of nuclear signaling in response to hormones. Insulin regulates the sub-cellular localization, stability and trans-activation potential of Sp1 by dynamically modulating its post-translational modification by O-linked beta-N-acetylglucosamine (O-GlcNAc) or phosphate residues. We briefly review the recent literature demonstrating that an involvement of Sp-family of transcription factors in the regulation of differential gene expression in response to hormones is more common than previously appreciated and may represent a key regulatory mechanism.
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Affiliation(s)
- Solomon S Solomon
- Research Service, VA Medical Center, 1030 Jefferson Avenue, Memphis, TN 38104, USA.
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18
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Bajwa A, Forster MN, Maiti A, Woolbright BL, Beckman MJ. Specific regulation of CYP27B1 and VDR in proximal versus distal renal cells. Arch Biochem Biophys 2008; 477:33-42. [PMID: 18593564 DOI: 10.1016/j.abb.2008.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 06/11/2008] [Accepted: 06/12/2008] [Indexed: 11/20/2022]
Abstract
In this study, we utilized murine renal proximal (MPCT-G) and distal (DKC-8) tubular epithelial cell lines to compare the gene expressions and promoter activities of 1,25(OH)(2)D(3) receptor (VDR) and 25-hydroxyvitamin D-1alpha-hydroxylase (CYP27B1) in response to 50 nM of parathyroid hormone (PTH) and changes in extracellular calcium (Ca(2+)) concentration. In MPCT-G cells, VDR gene expression was suppressed by PTH, whereas CYP27B1 gene expression was elevated in response to PTH. In DKC-8 cells, treatment of PTH significantly increased the relative gene expression of VDR by 6.5-fold while CYP27B1 gene expression was unchanged. High Ca(2+) exposure stimulated VDR gene expression and repressed CYP27B1 gene expression in both dose and time-dependent fashion in MPCT-G but not DKC-8 cells. The analysis of promoter activities and VDR protein levels corresponded with the gene expression data. We conclude that PTH-mediated decrease in VDR and increase in renal CYP27B1 is proximal cell-specific.
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MESH Headings
- 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/genetics
- 25-Hydroxyvitamin D3 1-alpha-Hydroxylase/metabolism
- Animals
- Blotting, Western
- Cell Line
- Immunohistochemistry
- Kidney Tubules, Distal/cytology
- Kidney Tubules, Distal/enzymology
- Kidney Tubules, Distal/metabolism
- Kidney Tubules, Proximal/cytology
- Kidney Tubules, Proximal/enzymology
- Kidney Tubules, Proximal/metabolism
- Mice
- Promoter Regions, Genetic
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Receptors, Calcitriol/metabolism
- Receptors, Calcium-Sensing/metabolism
- Steroid Hydroxylases/metabolism
- Vitamin D3 24-Hydroxylase
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Affiliation(s)
- Amandeep Bajwa
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298-0614, USA
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19
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Bezerra CNA, Girardi ACC, Carraro-Lacroix LR, Rebouças NA. Mechanisms underlying the long-term regulation of NHE3 by parathyroid hormone. Am J Physiol Renal Physiol 2008; 294:F1232-7. [DOI: 10.1152/ajprenal.00025.2007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The activity of the Na+/H+ exchanger NHE3 is regulated by a number of factors including parathyroid hormone (PTH). In the current study, we used a renal epithelial cell line, the opossum kidney (OKP) cell, to elucidate the mechanisms underlying the long-term effects of PTH on NHE3 transport activity and expression. We observed that NHE3 activity was reduced 6 h after addition of PTH, and this reduction persisted almost unaltered after 24 h. The decrease in activity was associated with diminished NHE3 cell surface expression at 6, 16, and 24 h after PTH addition, total cellular NHE3 protein at 16 and 24 h, and NHE3 mRNA abundance at 24 h. The lower levels of NHE3 mRNA were associated to a small, but significant, decrease in mRNA stability. Additionally, by analyzing the rat NHE3 gene promoter activity in OKP cells, we verified that the regulatory region spanning the segment −152 to +55 was mildly reduced under the influence of PTH. This effect was completely abolished by the presence of the PKA inhibitor KT 5720. In conclusion, long-term exposure to PTH results in reduction of NHE3 mRNA levels due to a PKA-dependent inhibitory effect on the NHE3 promoter and a small reduction of mRNA half-life, and decrease in the total amount of protein which is preceded by endocytosis of the apical surface NHE3. The decreased NHE3 expression is likely to be responsible for the reduction of sodium, bicarbonate, and fluid reabsorption in the proximal tubule consistently perceived in experimental models of PTH disorders.
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20
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Anderson PH, Hendrix I, Sawyer RK, Zarrinkalam R, Manavis J, Sarvestani GT, May BK, Morris HA. Co-expression of CYP27B1 enzyme with the 1.5kb CYP27B1 promoter-luciferase transgene in the mouse. Mol Cell Endocrinol 2008; 285:1-9. [PMID: 18313834 DOI: 10.1016/j.mce.2007.12.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 11/16/2007] [Accepted: 12/20/2007] [Indexed: 01/22/2023]
Abstract
The renal enzyme 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1), responsible for the synthesis of circulating. 1,25-dihydroxyvitamin D (1,25D), is also expressed in a number of non-renal tissues. The regulation of CYP27B1 expression by the short flanking promoter outside the kidney is, however, largely unknown. We have used a transgenic mice expressing the 1.5kb promoter of the human CYP27B1 gene fused to the firefly luciferase gene in order to investigate tissue-specific CYP27B1 expression. These transgenic animals demonstrated co-localised luciferase and endogenous CYP27B1 expression in kidney proximal convoluted tubular cells. Strong co-expression of luciferase and CYP27B1 also occurred in neurons and Purkinje cells of the cerebellum and in Leydig and Sertoli cells of the testes. Other tissues to exhibit CYP27B1-promoter directed luciferase activity included lung, prostate, trabecular bone and jejunum as well as the choroid epithelium. The tissue specific changes in luciferase activity were age-related. These findings demonstrate that the proximal 1.5kb 5' flanking region of the CYP27B1 gene directs the expression of CYP27B1 in a number of known and novel tissues in a specific manner.
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Affiliation(s)
- Paul H Anderson
- Endocrine Research Laboratory, Hanson Institute, Frome Road, Adelaide 5000, SA, Australia.
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21
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Maiti A, Hait NC, Beckman MJ. Extracellular Calcium-sensing Receptor Activation Induces Vitamin D Receptor Levels in Proximal Kidney HK-2G Cells by a Mechanism That Requires Phosphorylation of p38α MAPK. J Biol Chem 2008; 283:175-183. [DOI: 10.1074/jbc.m707269200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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22
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Turner AG, Dwivedi PP, May BK, Morris HA. Regulation of the CYP27B1 5'-flanking region by transforming growth factor-beta in ROS 17/2.8 osteoblast-like cells. J Steroid Biochem Mol Biol 2007; 103:322-5. [PMID: 17207990 DOI: 10.1016/j.jsbmb.2006.12.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Indexed: 11/16/2022]
Abstract
The biologically active form of vitamin D, 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), regulates osteoblast proliferation and differentiation. Production of 1,25(OH)(2)D(3) is catalysed by the enzyme 25-hydroxyvitamin D(3)-1alpha-hydroxylase (CYP27B1). Though highly expressed in the kidney, the CYP27B1 gene is also expressed in non-renal tissues including bone. It is hypothesised that local production of 1,25(OH)(2)D(3) by osteoblasts plays an autocrine or paracrine role. The aim of this study was to investigate what factors regulate expression of the CYP27B1 gene in osteoblast cells. ROS 17/2.8 osteoblast cells were transiently transfected with plasmid constructs containing the 5'-flanking sequence of the human CYP27B1 gene fused to a luciferase reporter gene. Cells were treated with either parathyroid hormone (PTH), 1,25(OH)(2)D(3), transforming growth factor-beta (TGF-beta) or insulin-like growth factor-1 (IGF-1) and luciferase activity was measured 24h later. The results showed that 1,25(OH)(2)D(3) did not alter expression of the reporter construct, however treatment with PTH, IGF-1 and TGF-beta decreased expression by 18, 53 and 58% respectively. The repressive action of TGF-beta was isolated to the region between -531 and -305bp. These data suggest that expression of the 5'-flanking region for the CYP27B1 gene in osteoblast cells may be regulated differently to that previously described in kidney cells.
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Affiliation(s)
- Andrew G Turner
- School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide 5000, Australia.
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23
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Dwivedi PP, Anderson PH, Tilley WD, May BK, Morris HA. Role of oncoprotein growth factor independent-1 (GFI1) in repression of 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1): a comparative analysis in human prostate cancer and kidney cells. J Steroid Biochem Mol Biol 2007; 103:742-6. [PMID: 17207994 DOI: 10.1016/j.jsbmb.2006.12.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1,25-Dihydroxyvitamin D (1,25D) inhibits growth of prostate cancer cells and has been proposed to play a protective role in prostate cancer. However, 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1), the enzyme responsible for the cellular synthesis of 1,25D, is repressed in prostate cancer cells. Recently, we have identified a role for the transcription factor, Growth Factor Independent-1 (GFI1) in the repression of the CYP27B1 gene in human prostate cancer cell lines. GFI1 is known to form a large protein complex with co-repressors that recruit histone deacetylases. We have proposed a model for the molecular repression of CYP27B1 gene expression. The formation of such a repressive complex on the inhibitory domain of the CYP27B1 gene in prostate cancer cells could lead to the silencing of gene expression either by inactivating nearby enhancer or proximal promoter domains and lead to cancer progression by reducing local production of 1,25D. These studies demonstrate that GFI1 may play a significant role in the down regulation of endogenous production of 1,25D in prostate cancer cells and could provide a novel insight to future diagnosis and treatment.
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Anderson PH, Sawyer RK, May BK, O'Loughlin PD, Morris HA. 25-Hydroxyvitamin D requirement for maintaining skeletal health utilising a Sprague-Dawley rat model. J Steroid Biochem Mol Biol 2007; 103:592-5. [PMID: 17267207 DOI: 10.1016/j.jsbmb.2006.12.086] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study the role of vitamin D to optimise bone architecture, we have developed an animal model to investigate the effects of frank vitamin D-deficiency as well as graded depletion of circulating 25-hydroxyvitamin D(3) (25D) levels on the skeleton. Rats fed on dietary vitamin D levels from 0 to 500 ng/day achieved diet-dependent circulating levels of 25D ranging from 11 to 115 nmol/L. Levels of serum 1,25-dihydroxyvitamin D(3) (1,25D) increased as dietary vitamin D increased between 0 and 200 ng/day at which point a maximum level was achieved and retained with higher vitamin D intakes. The renal levels of 25-hydroxyvitamin D-1alpha-hydroxylase (CYP27B1) mRNA were highest in animal groups fed on vitamin D between 0 and 300 ng/day. In contrast, renal 25-hydroxyvitamin D 24-hydroxylase (CYP24) mRNA levels increased as dietary vitamin D increased achieving maximum levels in animals receiving 500 ng vitamin D/day. This animal model of vitamin D depletion is suitable to provide invaluable information on the serum levels of 25D and dietary calcium intake necessary for optimal bone structure. Such information is essential for developing nutritional recommendations to reduce the incidence of osteoporotic hip fractures.
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Affiliation(s)
- P H Anderson
- Endocrine Bone Research Laboratory, Hanson Institute, Institute of Medical and Veterinary Science, Frome Road, Adelaide, SA 5000, Australia
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25
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Stoffels K, Overbergh L, Giulietti A, Verlinden L, Bouillon R, Mathieu C. Immune regulation of 25-hydroxyvitamin-D3-1alpha-hydroxylase in human monocytes. J Bone Miner Res 2006; 21:37-47. [PMID: 16355272 DOI: 10.1359/jbmr.050908] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 08/31/2005] [Accepted: 09/13/2005] [Indexed: 01/09/2023]
Abstract
UNLABELLED Monocytes express 1alpha-hydroxylase, the enzyme responsible for final hydroxylation of vitamin D3, in response to IFNgamma and CD14/TLR4 activation. Cross-talk between the JAK-STAT, the NF-kappaB, and the p38 MAPK pathways is necessary, and direct binding of C/EBPbeta to its recognition sites in the promoter of the 1alpha-hydroxylase gene is a prerequisite. INTRODUCTION The activated form of vitamin D3, 1,25(OH)2D3, known for its action in bone and mineral homeostasis, has important immunomodulatory effects. 1,25(OH)2D3 modulates the immune system through specific nuclear receptors, whereas macrophages produce 1,25(OH)2D3. In monocytes, the expression of 1alpha-hydroxylase, the enzyme responsible for final hydroxylation of vitamin D3, is regulated by immune stimuli. The aim of this study was to elucidate the intracellular pathways through which interferon (IFN)gamma and Toll-like receptor (TLR) modulation regulate expression of 1alpha-hydroxylase in monocytes/macrophages. MATERIALS AND METHODS Monocytes were isolated from peripheral blood mononuclear cells (PBMCs) and stimulated with IFNgamma (12.5 U/ml) and/or lipopolysaccharide (LPS; 100 ng/ml) for 48 h. The following inhibitors were used: janus kinase (JAK) inhibitor AG490 (50 microM), NF-kappaB inhibitor sulfasalazine (0.25 mM), p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 (5 microM). 1alpha-hydroxylase mRNA expression was monitored by qRT-PCR. Phosphorylation of transcription factors was studied by Western blotting. Transfection of mutated or deletion promoter constructs, cloned in the pGL3-luciferase reporter plasmid, were performed in the RAW264.7 cell line. Cells were stimulated with IFNgamma (100 U/ml) and LPS (100 microg/ml), and promoter activity was studied. Binding of signal transducer and activator of transcription (STAT)1alpha, NF-kappaB, and C/EBPbeta to their respective binding sites in the promoter was analyzed by gel shift assays. RESULTS 1alpha-hydroxylase mRNA expression in monocytes is synergistically induced by IFNgamma and CD14/TLR4 ligation and paralleled by 1,25(OH)2D3 production. This induction requires the JAK-STAT, NF-kappaB, and p38 MAPK pathways. Each of them is essential, because blocking individual pathways is sufficient to block 1alpha-hydroxylase expression (JAK inhibitor, 60% inhibition, p < 0.01; NF-kappaB inhibitor, 70% inhibition, p < 0.05; p38 MAPK inhibitor, 95% inhibition, p < 0.005). In addition, we show the involvement of the p38 MAPK pathway in phosphorylation of C/EBPbeta. Direct binding of C/EBPbeta to its recognition sites in the 1alpha-hydroxylase promoter is necessary to enable its immune-stimulated upregulation. CONCLUSION IFNgamma and CD14/TLR4 binding regulate expression of 1alpha-hydroxylase in monocytes in a synergistic way. Combined activation of the JAK-STAT, p38 MAPK, and NF-kappaB pathways is necessary, with C/EBPbeta most probably being the essential transcription factor controlling immune-mediated transcription.
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Affiliation(s)
- Katinka Stoffels
- Laboratory for Experimental Medicine and Endocrinology (LEGENDO), University Hospital Gasthuisberg, Catholic University of Leuven, Leuven, Belgium
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26
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Anderson PH, O'Loughlin PD, May BK, Morris HA. Modulation of CYP27B1 and CYP24 mRNA expression in bone is independent of circulating 1,25(OH)2D3 levels. Bone 2005; 36:654-62. [PMID: 15781002 DOI: 10.1016/j.bone.2005.01.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Revised: 01/10/2005] [Accepted: 01/24/2005] [Indexed: 11/23/2022]
Abstract
Circulating levels of 1,25-dihydroxyvitamin D (1,25D) are determined by bioactivation catalyzed by the renal 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1) and degradation through the action of the renal 25-hydroxyvitamin D 24-hydroxylase (CYP24). CYP27B1 and CYP24 are also present in bone cells, but little is known of their physiological role. The purpose of this study was to determine the changes that occur with aging on the expression of CYP27B1 and CYP24 mRNA in whole kidney and femora of female Sprague-Dawley rats. Real-time RT-PCR was used to measure CYP27B1, CYP24 and vitamin D receptor (VDR) mRNA levels in the kidneys and bones of animals aged between 3 weeks and 2 years. Circulating 1,25D levels decreased exponentially with age which was correlated with both reduced kidney CYP27B1 mRNA (R(2) = 0.72) and increased CYP24 mRNA levels (R(2) = 0.71). In the bone, CYP27B1 mRNA levels were maintained at their highest level throughout the ages of 3 to 15 weeks before decreasing in adult animals (P < 0.05). Bone CYP24 mRNA levels were positively correlated with bone CYP27B1 mRNA and not circulating 1,25D levels (R(2) = 0.74). Levels of bone CYP27B1 mRNA were positively correlated with distal femoral epiphyseal trabecular number (Tb.N) (R(2) = 0.74) and negatively with the trabecular thickness (Tb.Th) (R(2) = 0.56) in animals aged between 12 weeks and 2 years. These findings indicate that the regulation of CYP27B1 and CYP24 mRNA expression in the bone is unique from that in the kidney. The synthesis of 1,25D in bone tissue regulates bone CYP24 expression and is associated with bone mineralization suggesting that vitamin D metabolism has an autocrine or paracrine function.
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Affiliation(s)
- Paul H Anderson
- Endocrine Bone Research Laboratory, Hanson Institute, Adelaide, SA, Australia.
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27
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Omdahl JL, Bobrovnikova EV, Annalora A, Chen P, Serda R. Expression, structure-function, and molecular modeling of vitamin D P450s. J Cell Biochem 2003; 88:356-62. [PMID: 12520537 DOI: 10.1002/jcb.10366] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although vitamin D(3) is a natural product of a sunlight-mediated process in the skin, the secosteroid's biological function is dependent upon specific cytochrome P450 enzymes that mediate the parent vitamin's bioactivation and inactivation. Cytochrome P450C1 (CYP27B1) is the regulatory rate-limiting enzyme that directs the bioactivation process through introduction of a C-1alpha hydroxyl group. The resultant 1,25-dihydroxyvitamin D(3) (1,25D) is the biologically active secosteroid hormone that directs the multitude of vitamin D-dependent actions involved with calcium homeostasis, cellular differentiation and growth, and the immune response. The circulating and cellular level of 1,25D is regulated through a coordinated process involving the hormone's synthesis and degradation. Central to the degradation and turnover of 1,25D is the regulatory multi-catalytic cytochrome P450C24 (CYP24) enzyme that directs the introduction of C-24R groups onto targeted 25-hydroxy substrates. Discussed in this article is the action of the rat CYP24 to catalyze the side-chain oxidation and cleavage of 25-hydroxylated vitamin D metabolites. Expression and characterization of purified recombinant rat CYP24 is discussed in light of mutations directed at the enzyme's active site.
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Affiliation(s)
- J L Omdahl
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131-5221, USA.
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