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Hu X, Liu W, Yan Y, Liu H, Huang Q, Xiao Y, Gong Z, Du J. Vitamin D protects against diabetic nephropathy: Evidence-based effectiveness and mechanism. Eur J Pharmacol 2018; 845:91-98. [PMID: 30287151 DOI: 10.1016/j.ejphar.2018.09.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/06/2018] [Accepted: 09/27/2018] [Indexed: 02/08/2023]
Abstract
Vitamin D has been suggested to harbor multiple biological activities, among them the potential of vitamin D in the protection of diabetic nephropathy (DN) has attracted special attention. Both animal studies and clinical trials have documented an inverse correlation between low vitamin D levels and DN risk, and supplementation with vitamin D or its active derivatives has been demonstrated to improve endothelial cell injury, reduce proteinuria, attenuate renal fibrosis, and resultantly retard DN progression. Vitamin D exerts its pharmacological effects primarily via vitamin D receptor, whose activation inhibits the renin-angiotensin system, a key culprit for DN under hyperglycemia. The anti-DN benefit of vitamin D can be enhanced when administrated in combination with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers. Mechanistic studies reveal that pathways relevant to inflammation participate in the pathogenesis of DN, however, consumption of vitamin D-related products negatively regulates inflammatory response at multiple levels, indicated by inhibiting macrophage infiltration, nuclear factor-kappa B (NF-κB) activation, and production of such inflammatory mediators as transforming growth factor-β(TGF-β), monocyte chemoattractant protein 1(MCP-1), and regulated upon activation normal T cell expressed and secreted protein(RANTES). The robust anti-inflammatory property of vitamin D-related products allows them with a promising renoprotective therapeutic option for DN. This review summarizes new advances in our understanding of vitamin D-related products in the DN management.
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Affiliation(s)
- Xiaofang Hu
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Wanli Liu
- National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; Department of Nursing, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Yuanliang Yan
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Hengdao Liu
- Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 410013, Henan, China
| | - Qiong Huang
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Yi Xiao
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China
| | - Zhicheng Gong
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China.
| | - Jie Du
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, Hunan, China; National Clinical Research Center for Geriatric Disorders (XIANGYA), Xiangya Hospital, Central South University, Changsha 410008, Hunan, China.
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Kumar R, Tebben PJ, Thompson JR. Vitamin D and the kidney. Arch Biochem Biophys 2012; 523:77-86. [PMID: 22426203 PMCID: PMC3361542 DOI: 10.1016/j.abb.2012.03.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 03/01/2012] [Accepted: 03/02/2012] [Indexed: 12/22/2022]
Abstract
The kidney is essential for the maintenance of normal calcium and phosphorus homeostasis. Calcium and inorganic phosphorus are filtered at the glomerulus, and are reabsorbed from tubular segments by transporters and channels which are regulated by 1α,25-dihydroxyvitamin (1α,25(OH)(2)D) and parathyroid hormone (PTH). The kidney is the major site of the synthesis of 1α,25(OH)(2)D under physiologic conditions, and is one of the sites of 24,25-dihydroxyvitamin D (24,25(OH)(2)D) synthesis. The activity of the 25(OH)D-1α-hydroxylase, the mixed function oxidase responsible for the synthesis of 1α,25(OH)(2)D, is regulated by PTH, 1α,25(OH)(2)D, fibroblast growth factor 23 (FGF23), inorganic phosphorus and other growth factors. Additionally, the vitamin D receptor which binds to, and mediates the activity of 1α,25(OH)(2)D, is widely distributed in the kidney. Thus, the kidney, by regulating multiple transport and synthetic processes is indispensible in the maintenance of mineral homeostasis in physiological states.
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Affiliation(s)
- Rajiv Kumar
- Division of Nephrology and Hypertension, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Where is the vitamin D receptor? Arch Biochem Biophys 2012; 523:123-33. [PMID: 22503810 DOI: 10.1016/j.abb.2012.04.001] [Citation(s) in RCA: 394] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/30/2012] [Accepted: 04/01/2012] [Indexed: 02/08/2023]
Abstract
The vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and plays a central role in the biological actions of vitamin D. VDR regulates the expression of numerous genes involved in calcium/phosphate homeostasis, cellular proliferation and differentiation, and immune response, largely in a ligand-dependent manner. To understand the global function of the vitamin D system in physiopathological processes, great effort has been devoted to the detection of VDR in various tissues and cells, many of which have been identified as vitamin D targets. This review focuses on the tissue- and cell type-specific distribution of VDR throughout the body.
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Abstract
The kidney is the major, if not sole, site for the production of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), the biologically active form of vitamin D that can stimulate calcium reabsorption in the kidney and may provide renoprotective benefits. The biological effects of 1,25(OH)2D3 are mediated through a nuclear hormone receptor, known as the vitamin D receptor (VDR). It is well accepted that the VDR is present in the distal renal convoluted tubule cells; however, whether VDR is present in other kidney cell types is uncertain. Using a highly specific and sensitive anti-VDR antibody, we determined its distribution in the mouse kidney by immunohistochemistry. Our results show that the VDR is not only present in the distal but is also found in the proximal tubules, but at 24-fold lower levels. The VDR was also found in the macula densa of the juxtaglomerular apparatus, glomerular parietal epithelial cells, and podocytes. In contrast, the VDR is either very low or absent in interstitial fibroblasts, glomerular mesangial cells, and juxtaglomerular cells. Thus, identification of VDR in the proximal tubule, macula densa, and podocytes suggests that 1,25(OH)2D3 plays a direct role in these cells under normal conditions.
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Wang Y, Becklund BR, DeLuca HF. Identification of a highly specific and versatile vitamin D receptor antibody. Arch Biochem Biophys 2009; 494:166-77. [PMID: 19951695 DOI: 10.1016/j.abb.2009.11.029] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 11/24/2009] [Accepted: 11/25/2009] [Indexed: 12/31/2022]
Abstract
The active form of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) is critical for regulation of serum calcium and phosphorus levels and for proper maintenance of bone mineralization and neuromuscular function. Biological effects of 1,25(OH)2D3 are mediated through a nuclear steroid hormone receptor, known as the vitamin D receptor (VDR). The discovery of VDR in a number of different cell and tissue types, suggests that the physiological role of vitamin D may extend beyond the regulation of calcium homeostasis and bone function. Unfortunately, identification of tissues expressing VDR has been controversial due to low abundance of the receptor and quality of the antibodies used. Therefore, we elected to characterize a panel of commercially available VDR antibodies in order to identify antibodies with high specificity and sensitivity. To address these objectives, we have used multiple immunoassays to determine VDR expression in tissues from several organs from multiple species employing tissues from VDR knockout mice as critical negative controls. Many of the antibodies tested showed nonspecific binding that can account for divergent reports. However, one antibody, identified as D-6, is highly specific and extremely sensitive. The specificity, sensitivity, and versatility of this antibody make it the preferred antibody for identifying VDR expression in target tissues using immunological methods.
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Affiliation(s)
- Yongji Wang
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706-1544, USA
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Xue Y, Fleet JC. Intestinal vitamin D receptor is required for normal calcium and bone metabolism in mice. Gastroenterology 2009; 136:1317-27, e1-2. [PMID: 19254681 PMCID: PMC2695717 DOI: 10.1053/j.gastro.2008.12.051] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 11/25/2008] [Accepted: 12/11/2008] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Vitamin D receptor (VDR)-knockout mice develop severe hypocalcemia and rickets, accompanied by disruption of active intestinal calcium absorption. To specifically study the effects of VDR in intestinal calcium absorption, we investigated whether restoration of intestinal VDR is sufficient to recover the phenotype of VDR-knockout mice. METHODS We generated mice with intestine-specific transgenic expression of human VDR and crossed them to VDR knockout mice. The intestine, kidney, and bone phenotypes of the VDR- knockout mice with intestine-specific expression of human VDR (knockout/transgenic [KO/TG]) were analyzed. RESULTS Transgenic expression of VDR in the intestine of VDR-knockout mice normalized duodenal vitamin D-regulated calcium absorption as well as vitamin D-regulated calcium binding protein D9k and TRPV6 gene expression in the duodenum and proximal colon. As a result, animal growth and the serum levels of calcium and parathyroid hormone were normalized in KO/TG mice. Other phenotypes were revealed when calcium metabolism was normalized in KO/TG mice: serum 1,25 dihydroxyvitamin D levels were higher in KO/TG mice than normal mice owing to reduced renal expression of the vitamin D-degrading enzyme CYP24, urinary calcium excretion was higher and associated with lower renal calcium binding protein D9k and calcium binding protein D28k than normal mice, and bone density and volume increased in KO/TG compared with normal mice owing to increased mineral apposition rate and osteoblast number. CONCLUSIONS Intestinal VDR and vitamin D-regulated intestinal calcium absorption are critical for controlling whole-body calcium metabolism in growing mice. Normalizing intestinal calcium absorption and metabolism reveals essential roles for VDR in control of bone formation and renal control of serum 1,25(OH)2D and urinary calcium excretion.
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Affiliation(s)
- Yingben Xue
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907-2059
| | - James C. Fleet
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907-2059,Center for Gene-Environment Interactions, Purdue University, West Lafayette, IN 47907-2059,Corresponding author: James C. Fleet, Ph.D., Purdue University, 700 West State St., West Lafayette, IN 47906-2059, (O) 1-765-494-0302, (F) 1-765-494-0906, E-mail address:
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7
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Abstract
Vitamin D deficiency has been widely reported in all age groups in recent years. Rickets has never been eradicated in developed countries, and it most commonly affects children from recent immigrant groups. There is much evidence that current vitamin D guidelines for the neonatal period, 5-10 microg (200-400 IU)/day, prevent rickets at the typical calcium intakes in developed countries. The annual incidence of vitamin D-deficiency rickets in developed countries ranges between 2.9 and 7.5 cases per 100,000 children. The prevalence of vitamin D deficiency in mothers and their neonates is remarkable, and the results of one study suggest that third-trimester 25-hydroxyvitamin D (25(OH)D) is associated with fetal bone mineral accrual that may affect prepubertal bone mass accumulation. Beyond infancy, the evidence indicates that 5 microg (200 IU)/day of vitamin D has little effect on vitamin D status as measured by the serum 25(OH)D concentration. Two randomized clinical trials show that higher vitamin D intake improves one-year gain in bone density in adolescent girls. The functions of vitamin D extend beyond bone to include immune system regulation and anti-proliferative effects on cells. Early life vitamin D inadequacy is implicated in the risk of bone disease, autoimmune disease, and certain cancers later in life; however, long-term interventional studies do not exist to validate the widespread implementation of greater vitamin D consumption. Here we review the available data concerning vitamin D status and health effects of vitamin D in pregnancy through to and including adolescence.
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Affiliation(s)
- Samantha Kimball
- Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
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Yamagata M, Kimoto A, Michigami T, Nakayama M, Ozono K. Hydroxylases involved in vitamin D metabolism are differentially expressed in murine embryonic kidney: application of whole mount in situ hybridization. Endocrinology 2001; 142:3223-30. [PMID: 11416045 DOI: 10.1210/endo.142.7.8122] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this study we examined the expression of 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase) and 25-hydroxyvitamin D-24-hydroxylase (24-hydroxylase) by RT-PCR and whole mount in situ hybridization using organ culture of kidney taken from mouse embryo. First, the kidneys of mouse embryo at 11.5-17.5 days gestation were cultured in the presence or absence of forskolin and 1,25-dihydroxyvitamin D(3) [1alpha,25-(OH)(2)D(3)]. Forskolin and 1alpha,25-(OH)(2)D(3) induced the expression of 1alpha-hydroxylase and 24-hydroxylase, respectively, in a dose- and time-dependent manner. In the absence of stimulants, the expression of 1alpha-hydroxylase and 24-hydroxylase was detected from days 13.5-17.5 gestation. The expression of vitamin D receptor and megalin was detected from days 13.5 and 11.5, respectively. Next, signals for the expression of either 1alpha-hydroxylase or 24-hydroxylase were detected by whole mount in situ hybridization in kidney explants taken from embryo at 15.5 days gestation after the appropriate stimulation. However, the localization of signals differed between the two enzymes; 1alpha-hydroxylase messenger RNA was expressed in the inner area of the kidney explants, whereas 24-hydroxylase messenger RNA was expressed in the surface area. The expression of both hydroxylases was restricted to the epithelium of developing renal tubules. The pattern of megalin expression was similar to that of 1alpha-hydroxylase expression. To confirm the difference in distribution of 1alpha-hydroxylase and 24-hydroxylase transcripts, the explants were hybridized with probes for both 1alpha-hydroxylase and 24-hydroxylase using double labeling techniques after simultaneous stimulation with forskolin and 1alpha,25-(OH)(2)D(3), resulting in the detection at different locations of positive signals for the two enzymes. These results suggest that the expression of 1alpha-hydroxylase is induced in a distinct epithelium of renal tubules from that of 24-hydroxylase even at the early stage of kidney development before glomerulogenesis.
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Affiliation(s)
- M Yamagata
- Department of Environmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan
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Ritchie G, Kerstan D, Dai LJ, Kang HS, Canaff L, Hendy GN, Quamme GA. 1,25(OH)(2)D(3) stimulates Mg2+ uptake into MDCT cells: modulation by extracellular Ca2+ and Mg2+. Am J Physiol Renal Physiol 2001; 280:F868-78. [PMID: 11292630 DOI: 10.1152/ajprenal.2001.280.5.f868] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The distal convoluted tubule plays a significant role in renal magnesium conservation. Although the cells of the distal convoluted tubule possess the vitamin D receptor, little is known about the effects of 1alpha,25-dihydroxyvitamin D [1,25(OH)(2)D(3)] on magnesium transport. In this study, we examined the effect of 1,25(OH)(2)D(3) on distal cellular magnesium uptake and the modulation of this response by extracellular Ca2+ and Mg2+ in an immortalized mouse distal convoluted tubule (MDCT) cell line. MDCT cells possess the divalent cation-sensing receptor (CaSR) that responds to elevation of extracellular Ca2+ and Mg2+ concentrations to diminish peptide hormone-stimulated Mg2+ uptake. Mg2+ uptake rates were determined by microfluorescence in Mg2+ -depleted MDCT cells. Treatment of MDCT cells with 1,25(OH)(2)D(3) for 16-24 h stimulated basal Mg2+ uptake in a concentration-dependent manner from basal levels of 164 +/- 5 to 210 +/- 11 nM/s, representing a 28 +/- 3% change. Pretreatment with actinomycin D or cycloheximide abolished 1,25(OH)(2)D(3)-stimulated(.)Mg2+ uptake (154 +/- 18 nM/s), suggesting that 1,25(OH)(2)D(3) stimulates Mg2+ uptake through gene activation and protein synthesis. Elevation of extracellular Ca2+ inhibited 1,25(OH)(2)D(3)-stimulated Mg2+ uptake (143 +/- 5 nM/s). Preincubation of the cells with an antibody to the CaSR prevented the inhibition by elevated extracellular Ca2+ of 1,25(OH)(2)D(3)-stimulated Mg2+ uptake (202 +/- 8 nM/s). Treatment with an antisense CaSR mRNA oligodeoxynucleotide also abolished the effects of extracellular Ca2+ on 1,25(OH)(2)D(3)-responsive Mg2+ entry. This showed that elevated extracellular calcium modulates 1,25(OH)(2)D-mediated responses through the CaSR. In summary, 1,25(OH)(2)D(3) stimulated Mg2+ uptake in MDCT cells, and this is dependent on de novo protein synthesis. Elevation of extracellular Ca2+, acting via the CaSR, inhibited 1,25(OH)(2)D(3)-stimulated Mg2+ entry. These data indicate that 1,25(OH)(2)D(3) has important effects on the control of magnesium entry in MDCT cells and these responses can be modulated by extracellular divalent cations.
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Affiliation(s)
- G Ritchie
- Department of Medicine, University Hospital, University of British Columbia, Vancouver, British Columbia V6T 1Z3
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Dai LJ, Ritchie G, Kerstan D, Kang HS, Cole DE, Quamme GA. Magnesium transport in the renal distal convoluted tubule. Physiol Rev 2001; 81:51-84. [PMID: 11152754 DOI: 10.1152/physrev.2001.81.1.51] [Citation(s) in RCA: 250] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The distal tubule reabsorbs approximately 10% of the filtered Mg(2+), but this is 70-80% of that delivered from the loop of Henle. Because there is little Mg(2+) reabsorption beyond the distal tubule, this segment plays an important role in determining the final urinary excretion. The distal convoluted segment (DCT) is characterized by a negative luminal voltage and high intercellular resistance so that Mg(2+) reabsorption is transcellular and active. This review discusses recent evidence for selective and sensitive control of Mg(2+) transport in the DCT and emphasizes the importance of this control in normal and abnormal renal Mg(2+) conservation. Normally, Mg(2+) absorption is load dependent in the distal tubule, whether delivery is altered by increasing luminal Mg(2+) concentration or increasing the flow rate into the DCT. With the use of microfluorescent studies with an established mouse distal convoluted tubule (MDCT) cell line, it was shown that Mg(2+) uptake was concentration and voltage dependent. Peptide hormones such as parathyroid hormone, calcitonin, glucagon, and arginine vasopressin enhance Mg(2+) absorption in the distal tubule and stimulate Mg(2+) uptake into MDCT cells. Prostaglandin E(2) and isoproterenol increase Mg(2+) entry into MDCT cells. The current evidence indicates that cAMP-dependent protein kinase A, phospholipase C, and protein kinase C signaling pathways are involved in these responses. Steroid hormones have significant effects on distal Mg(2+) transport. Aldosterone does not alter basal Mg(2+) uptake but potentiates hormone-stimulated Mg(2+) entry in MDCT cells by increasing hormone-mediated cAMP formation. 1,25-Dihydroxyvitamin D(3), on the other hand, stimulates basal Mg(2+) uptake. Elevation of plasma Mg(2+) or Ca(2+) inhibits hormone-stimulated cAMP accumulation and Mg(2+) uptake in MDCT cells through activation of extracellular Ca(2+)/Mg(2+)-sensing mechanisms. Mg(2+) restriction selectively increases Mg(2+) uptake with no effect on Ca(2+) absorption. This intrinsic cellular adaptation provides the sensitive and selective control of distal Mg(2+) transport. The distally acting diuretics amiloride and chlorothiazide stimulate Mg(2+) uptake in MDCT cells acting through changes in membrane voltage. A number of familial and acquired disorders have been described that emphasize the diversity of cellular controls affecting renal Mg(2+) balance. Although it is clear that many influences affect Mg(2+) transport within the DCT, the transport processes have not been identified.
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Affiliation(s)
- L J Dai
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Lee YF, Young WJ, Lin WJ, Shyr CR, Chang C. Differential regulation of direct repeat 3 vitamin D3 and direct repeat 4 thyroid hormone signaling pathways by the human TR4 orphan receptor. J Biol Chem 1999; 274:16198-205. [PMID: 10347174 DOI: 10.1074/jbc.274.23.16198] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In situ hybridization analysis demonstrated that abundant testicular orphan receptor (TR4) transcripts were detected in kidney, intestine, and bone, which are vitamin D3 target organs. Cell transfection studies also demonstrated that the expression of the vitamin D3 target gene, 25-hydroxyvitamin D3 24-hydroxylase, can be repressed by TR4 through high affinity binding (Kd = 1.32 nM) to the direct repeat 3 vitamin D3 receptor response element (DR3VDRE). This TR4-mediated repression of DR3VDRE is in contrast to our earlier report that TR4 could induce thyroid hormone target genes containing a direct repeat 4 thyroid hormone response element (DR4T3RE). Electrophoretic mobility shift assay using several TR4 monoclonal antibodies when combined with either TR4-DR3VDRE or TR4-DR4T3RE showed a distinct supershifted pattern, and proteolytic analysis further demonstrated distinct digested peptides with either TR4-DR3VDRE or TR4-DR4T3RE. These results may therefore suggest that TR4 can adapt to different conformations once bound to DR3VDRE or DR4T3RE. The consequence of these different conformations of TR4-DR3VDRE and TR4-DR4T3RE may allow each of them to recruit different coregulators. The differential repression of TR4-mediated DR3VDRE and DR4T3RE transactivation by the receptor interacting protein 140, a TR4 coregulator, further strengthens our hypothesis that the specificity of gene regulation by TR4 can be modulated by protein-DNA and protein-protein interactions.
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Affiliation(s)
- Y F Lee
- George Whipple Laboratory for Cancer Research, Department of Pathology, Urology, Radiation Oncology, and The Cancer Center, University of Rochester Medical Center, Rochester, New York 14642, USA
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Veenstra TD, Prüfer K, Koenigsberger C, Brimijoin SW, Grande JP, Kumar R. 1,25-Dihydroxyvitamin D3 receptors in the central nervous system of the rat embryo. Brain Res 1998; 804:193-205. [PMID: 9757035 DOI: 10.1016/s0006-8993(98)00565-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have mapped areas within the central nervous system (CNS) of the developing fetal rat which immunostain for the 1,25-dihydroxyvitamin D3 receptor (VDR). The VDR was detected from days 12 to 21 of gestation throughout the CNS; immunostaining was particularly intense in the neuroepithelium and within the differentiating fields of various areas of the brain. Cells within the spinal cord, dorsal root, and other ganglia exhibited positive staining for the VDR. The intensity of staining for the VDR diminished or disappeared in the neuroepithelium throughout the CNS during the later days of development, while in the differentiating fields single VDR immunoreactive cells were observed. The presence of the VDR in the CNS was confirmed by in situ hybridization and RNA-based polymerase chain reaction methods with di-deoxy sequencing of the resultant DNA product. These results support the hypothesis that 1, 25-dihydroxyvitamin D3, through interactions with the VDR, may play a role in the development of the CNS.
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Affiliation(s)
- T D Veenstra
- Nephrology Research Unit, Mayo Clinic/Foundation, Rochester, MN 55905, USA
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Mangat H, Peterson LN, Burns KD. Hypercalcemia stimulates expression of intrarenal phospholipase A2 and prostaglandin H synthase-2 in rats. Role of angiotensin II AT1 receptors. J Clin Invest 1997; 100:1941-50. [PMID: 9329957 PMCID: PMC508383 DOI: 10.1172/jci119725] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In chronic hypercalcemia, inhibition of thick ascending limb sodium chloride reabsorption is mediated by elevated intrarenal PGE2. The mechanisms and source of elevated PGE2 in hypercalcemia are not known. We determined the effect of hypercalcemia on intrarenal expression of cytosolic phospholipase A2 (cPLA2), prostaglandin H synthase-1 (PGHS-1), and prostaglandin H synthase-2 (PGHS-2), enzymes important in prostaglandin production. In rats fed dihydrotachysterol to induce hypercalcemia, Western blot analysis revealed significant upregulation of both cPLA2 and PGHS-2 in the kidney cortex and the inner and outer medulla. Immunofluorescence localized intrarenal cPLA2 and PGHS-2 to interstitial cells of the inner and outer medulla, and to macula densa and cortical thick ascending limbs in both control and hypercalcemic rats. Hypercalcemia had no effect on intrarenal expression of PGHS-1. To determine if AT1 angiotensin II receptor activation was involved in the stimulation of cPLA2 and PGHS-2 in hypercalcemia, we treated rats with the AT1 receptor antagonist, losartan. Losartan abolished the polydipsia associated with hypercalcemia, prevented the increase in cPLA2 protein in all regions of the kidney, and diminished PGHS-2 expression in the inner medulla. In addition, losartan completely prevented the increase in urinary PGE2 excretion in hypercalcemic rats. Intrarenal levels of angiotensin II were unchanged in hypercalcemia. These data indicate that hypercalcemia stimulates intrarenal cPLA2 and PGHS-2 protein expression. Our results further support a role for angiotensin II, acting on AT1 receptors, in mediating this stimulation.
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Affiliation(s)
- H Mangat
- Department of Physiology, University of Ottawa and Ottawa General Hospital, Ottawa, Ontario, Canada K1H 8M5
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14
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Sugawara A, Sanno N, Takahashi N, Osamura RY, Abe K. Retinoid X receptors in the kidney: their protein expression and functional significance. Endocrinology 1997; 138:3175-80. [PMID: 9231765 DOI: 10.1210/endo.138.8.5351] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Retinoid X receptors (RXRs) heterodimerize with 1,25-dihydroxyvitamin D3 (VD) receptor (VDR), and play important roles in VD-regulated transactivation. VD acts on many tissues including kidney for the regulation of calcium homeostasis. In the kidney, the expression of VDR in the tubular cells has been well studied. In contrast, little is known about the localization and the functional significance of RXRs there. In order to elucidate these questions, we first performed immunohistochemical analyses of rat kidney using isoform-specific antimouse RXR antibodies we have previously reported. Interestingly, all RXR isoforms, predominantly RXR alpha, mainly localized to the proximal and the distal tubules, but not to the glomeruli. The serial section staining using anti-VDR antibody showed the colocalization of RXR alpha and VDR in those tubular cells. In order to elucidate the functional significance of endogenous receptors in the tubular cells, we next performed transient transfection studies using the tubular-cell derived Madin-Darby bovine kidney cells, which express both endogenous VDR and RXR. We transfected a reporter plasmid containing direct repeat 3 (DR3) sequence, to which only RXR/VDR heterodimer can bind, and found that VD and 9-cis retinoic acid, as well as VD and RXR selective agonist LG100153, had an additive effect for the DR3 transactivation. Taken together, we speculate that endogenous RXRs co-localize with VDR, and coregulate VD-dependent genes in the tubular cells of the kidney as RXR/VDR heterodimer.
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Affiliation(s)
- A Sugawara
- The 2nd Department of Internal Medicine, Tohoku University School of Medicine, Aoba-ku, Sendai, Japan
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Barsony J, Renyi I, McKoy W. Subcellular distribution of normal and mutant vitamin D receptors in living cells. Studies with a novel fluorescent ligand. J Biol Chem 1997; 272:5774-82. [PMID: 9038191 DOI: 10.1074/jbc.272.9.5774] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To understand the subcellular localization of the vitamin D receptor (VDR) and to measure VDR content in single cells, we recently developed a fluorescent labeled ligand, 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY)-calcitriol. This tagged hormone has intact biological activity, high affinity and specific binding to the receptor, and enhanced fluorescent emission upon receptor binding. Using BODIPY-calcitriol, here we monitored the subcellular distribution of VDR in living cultured cells by microscopy. Time course studies showed that an equilibrium between the cytoplasmic and nuclear hormone binding developed within 5 min and was maintained thereafter. We found a substantial proportion of VDR residing in the cytoplasm, colocalized with endoplasmic reticulum, the Golgi complex, and microtubules. Confocal microscopy clarified the presence of VDR within discrete regions of the nucleus and along the nuclear envelope. There was no VDR in the plasma membrane. Low affinity BODIPY-calcitriol binding sites were in the mitochondria. Mutations in the VDR gene selectively and specifically altered BODIPY-calcitriol distribution. Defects in the hormone binding region of VDR prevented both nuclear and cytoplasmic hormone binding. Defects in the DNA binding region decreased the nuclear retention of VDR and prevented localization to nuclear foci. These results with BODIPY-calcitriol reveal cytoplasmic VDR localization in living cells and open the possibility of studying the three-dimensional architecture of intranuclear target sites.
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Affiliation(s)
- J Barsony
- Laboratory of Cell Biochemistry and Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
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