Vitamin D Receptor Protein Research Articles

Vitamin D receptor and 1α-hydroxylase are highly expressed in lungs of mice infected with H9N2 avian influenza viruses

The H9N2 avian influenza viruses infect poultry worldwide, and can potentially cause a human pandemic without adaptation. Vitamin D3 (D3) is increasingly being recognized for its extra-skeletal roles, such as the inflammatory and immune responses to infection. The aim of this study was to analyze the changes in vitamin D metabolizing enzymes and vitamin D receptor (VDR) in the lung tissues of mice infected with H9N2. The mice were intranasally inoculated with the appropriate dose of the virus, and various clinical indices were measured on days 3, 7, 14 and 21 post-infection. H9N2 infection significantly increased the expression levels of 1α-hydroxylase mRNA and protein, which is the activating enzyme of 25-hydroxyvitamin D (25(OH)D3), but had no significant effect on the 25(OH)D3 inactivating enzyme 24-hydroxylase, indicating that inactive D3 might be converted to its active form in the H9N2-infected lungs. Furthermore, a significant increase was also observed in the VDR mRNA and protein levels, suggesting enhanced responsiveness of the lung tissues to 1, 25(OH)2D3 post H9N2 infection. In addition, daily 25(OH)D3 injection from day 2–14 post-infection did not affect the clinical signs, virus replication and cytokine (IL-1β and TNF-α) production in the lungs of the infected mice. Given that the biological effects of D3 rely on its activation, and the binding of 1, 25(OH)2D3 to VDR in specific tissues, our findings provide novel insights into the possible role of vitamin D in the development and progression of influenza.

Cholecalciferol Mediates Apoptosis in Siha Cervical Cancer Line via Autocrine Mechanisms

Cervical cancer disproportionately affects low-resource countries and is a significant health burden in South Africa. Pre-clinical studies have demonstrated numerous anti-cancer actions of vitamin D metabolites. Here, the anti-cancer action of the vitamin D precursor, cholecalciferol, was investigated in a high-grade cervical cancer cell line, SiHa. SiHa cell cultures were treated with a range of cholecalciferol doses (26 nM, 104 nM, 260 nM and 2600 nM) for 72 hours. Cell count and viability were assessed by crystal violet and trypan blue assays, respectively. Apoptotic cell death was investigated by flow cytometry, which measured mitochondrial membrane potential (∆Ψm), phosphatidylserine (PS) externalisation, effector caspase activation and the expression of DNA damage markers. Additionally, brightfield microscopy and transmission electron microscopy (TEM) were respectively used to characterise morphological and ultrastructural features of apoptosis. Expression of the vitamin D metabolising system (VDMS) – consisting of cholecalciferol activating (CYP2R1 and CYP27A1), calcidiol activating (CYP27B1) and calcidiol inactivating (CYP24A1) enzymes, and the vitamin D receptor (VDR) – was assessed by qPCR and Western blots. Data were analysed using a one-way ANOVA and Bonferroni post-hoc tests and p < 0.05 was considered statistically significant. Significant decreases in cell count (p = 0.011) and cell viability (p < 0.0001) were identified in SiHa cells treated with 2600 nM cholecalciferol. Furthermore, biochemical markers at 2600 nM treatment were significant for apoptosis, and included decreased ∆Ψm (p = 0.0145); increased PS externalisation (p = 0.0439); terminal caspase activation (p = 0.0025); and nuclear damage (p = 0.004). Moreover, biochemical apoptosis was corroborated by classical apoptotic features observed by brightfield microscopy and TEM. Additionally, a significant increase in CYP2R1 gene (p < 0.0001) and protein (p = 0.021) expression, and a converse significant decrease in CYP27B1 gene (p = 0.003) and protein expression (p = 0.031) were observed at 2600 nM cholecalciferol treatment. Furthermore, significant increases in VDR gene (p = 0.033) and protein (p = 0.04) expression, and CYP24A1 gene (p < 0.0001) and protein (p = 0.0274) expression were observed at 2600 nM cholecalciferol. In summary, high-dose cholecalciferol treatment of SiHa cervical cancer cells inhibits cell growth, induces apoptosis, and furthermore, upregulates CYP2R1 and VDR expression. Taken together, these findings suggest that autocrine activation of cholecalciferol to calcidiol may mediate VDR signalling of cell growth inhibition, and apoptosis in SiHa experimental cultures.

Redefining the targets of the vitamin D receptor (VDR) utilizing a novel VDR reporter mouse.

Abstract The vitamin D receptor (VDR) is a ligand-activated nuclear protein that regulates gene transcription. Vitamin D target cells are identified by the expression of VDR. Kidney and colon epithelial cells constitutively express high levels of the VDR. Immune cells also express the VDR; however, at significantly lower levels. Western blots show very low expression of the VDR in spleen, and lymph nodes. Gene expression studies in macrophage, B cells and T cells showed that activation for 24–48 hours increased the VDR mRNA levels. We have developed transgenic mice that express Cre recombinase within the VDR locus (VDRcre) and crossed these with a reporter line (Tdtomatofl/fl). Cre expression in the VDR locus results in a VDR +/− mice. The frequencies of immune cells were similar between VDR−/− and VDR +/− mice. The VDRcre expressing offspring had pink skin. Kidneys, small intestine and colon were also distinctly pink suggesting high expression of the Tdtomato-VDR reporter. Splenic T cells, activated with CD3e antibody showed upregulation of VDR mRNA and protein. Regardless of activation status, naive, effector or memory T cells had similar and high levels of the VDR reporter. VDR expression was detected at various stages of T cell thymic development with a 80% in the CD4-CD8- cells and 90% of CD4+CD8+ cells, 84% CD4+ and 88% CD8+ thymocytes. High expression of the VDR reporter in multiple T cell types and precursors suggests that the VDR is expressed throughout the life of a T cell. Future work will identify immune cells negative for the VDR reporter and the kinetics of VDR expression following activation in various cell types.

Association of Vitamin D receptor gene variations with Gastric cancer risk in Kashmiri population.

Vitamin D receptor (VDR) mediates cellular processes like cell cycle arrest and apoptosis which effect cancer susceptibility. VDR single nucleotide polymorphisms (SNPs) have a significant influence on functioning of VDR protein and subsequently contribute to the risk of cancer occurrence and progression. The present case-control study was carried out between 2016 and 2020 to investigate the association of VDR BsmI/ApaITaqI SNPs with Gastric Cancer (GC) risk in ethnic Kashmiri population not only for establishing a molecular marker for GC but also to facilitate the outcomes of personalized medicine in future. The polymorphisms of BsmI and ApaI of the VDR gene were evaluated using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism followed by Di-Deoxy Sanger sequencing in 143 GC cases and 150 controls. The mean age (in years) was 53.5 ± 7.92 and 51.2 ± 8.25 and mean Body mass index was 22.68 ± 4.27kg/m2 and 23.81 ± 3.71kg/m2 for cases and controls respectively. The mean CEA levels of GC cases was 40.2 ± 10.9ng/ml. Genotypic distribution of VDR BsmI differed significantly between GC cases and controls (GG vs GA + AA; adjusted P = 0.014) and followed dominant mode of inheritence. Stratification of VDR BsmI revealed that frequency of variant genotype (GA + AA) was significantly higher in Preobese GC cases (P = 0.001), GC patients consuming < 5 cups of salt tea/day (P < 0.0001) and with no family history of gastrointestinal cancer (P = 0.014) compared to healthy controls. ATC haplotype associated with high GC risk. In conclusion, our study suggests that VDR BsmI SNP has a significant association with increased risk of GC especially in preobese population and BsmI/ApaITaqI SNPs significantly decreased the overall survival in GC patients of Kashmiri population.

Association between vitamin D and ovarian cancer development in BRCA1 mutation carriers.

Objective: Women with inherited mutations in BRCA1 gene have a high (40–70%) genetic risk of developing ovarian cancer. Epidemiological studies suggest an inverse correlation between serum vitamin D (VD) levels and the risk of ovarian cancer, but there is a lack of data from BRCA1 mutation (BRCA1mut) carriers. Therefore, we investigated VD levels and actions in cancer free women with BRCA1 mutations.Materials and Methods: Blood, ovary and fallopian tube samples were collected from healthy pre-menopausal women with BRCA1mut and without BRCA1 mutations (BRCAwt). Serum calcifediol (major circulating form of VD) concentrations were measured by electrochemiluminescence immunoassay. Immunohistochemistry was performed on paraffin-embedded ovarian and fallopian tube sections to determine vitamin D receptor (VDR) expression. Ovarian surface epithelial cells (OSEs) from BRCA1mut carriers were cultured with or without calcitriol supplementation for 72 hrs. VDR protein levels, cell proliferation and cell viability were analyzed.Results: BRCA1mut women had lower serum calcifediol levels compared to BRCAwt women (p = 0.003). VDR protein expression was evident in ovarian and the fallopian tube epithelium of BRCAwt patients, but was reduced in BRCA1mut women. Calcitriol (biologically active VD) supplementation elevated VDR expression in cultured BRCA1mut OSEs (p = 0.005) and decreased cell proliferation rates in a dose-dependent manner without inducing apoptosis.Conclusions: VD biosynthesis and signaling via VDR in the ovarian and fallopian tube epithelium are impaired in BRCA1mut women. VD treatment may limit BRCA1mut epithelial cell proliferation without affecting cell viability, providing a rationale for exploring the potential for VD in ovarian cancer prevention in BRCA1mut carriers.

A single bout of high-intensity exercise modulates the expression of vitamin D receptor and vitamin D-metabolising enzymes in horse skeletal muscle.

The expressions of vitamin D receptor (VDR) and vitamin D-metabolising enzymes (CYP27B1 and CYP24A1) in skeletal muscle have been reported. However, the regulation of this vitamin D system in horse skeletal muscle after high-intensity exercise has not yet been elucidated. To investigate the effect of high-intensity exercise on the expression of vitamin D system-related proteins in horse skeletal muscle and its associations with skeletal muscle stem cell (SMSC) activity and serum 25(OH)D level. Longitudinal study. Six healthy ponies (5 geldings, 1 mare; age 6.3±2.2years) were studied. Serum and muscle samples were taken from the jugular vein and gluteus medius respectively. Samples were collected at pre-exercise, post-exercise, 1 and 3weeks after a single bout of high-intensity exercise. Protein expression levels of VDR, CYP27B1, CYP24A1, OxPhos and Pax7 (SMSC marker) were determined using immunohistochemical analysis. Oxidative capacity and intramuscular glycogen content were evaluated using histochemical analysis. Blood biochemistry was analysed for lactate concentration and creatine kinase (CK), and 25(OH)D activity. High-intensity exercise significantly upregulated Pax7 and VDR protein expression, which correlated with significantly increased blood lactate and serum CK levels immediately post-exercise. Serum 25(OH)D2 level correlated with CYP27B1 protein expression in skeletal muscle, and it reduced significantly immediately post-exercise and at 1 and 3weeks post-exercise. However, CYP24A1 protein expression was unchanged throughout study periods. The healthy ponies could not represent a fit population of racehorses and eventers. The rapid increase in Pax7 and VDR protein expression along with serum CK level after high-intensity exercise demonstrated an association between SMSC activity and activation of the vitamin D system in response to muscle injury in horses. Moreover, a decrease in CYP27B1 protein expression, correlated with a reduction in serum 25(OH)D2 , may indicate a compromised vitamin D metabolism after high-intensity exercise.

Vitamin D receptor knockdown attenuates the antiproliferative, pro‑apoptotic and anti‑invasive effect of vitamin D by activating the Wnt/β‑catenin signaling pathway in papillary thyroid cancer.

Vitamin D and the vitamin D receptor (VDR) complex have been reported to inhibit the growth of several types of tumor; however, their function in papillary thyroid cancer (PCT) remains unknown. In addition, the Wnt/β-catenin signaling pathway was discovered to serve a critical role in the pathology of PCT. Therefore, the present study aimed to determine the role of the VDR and its association with Wnt/β-catenin signaling in vitamin D-treated PTC cells. VDR expression was detected in human PTC cells (including MDA-T120, MDA-T85, SNU-790 and IHH4 cells) and thyroid follicular cells (Nthy-ori 3–1 cells). SNU-790 and IHH4 cells were infected with KD-VDR or negative control (KD-NC) lentiviruses, treated with 1,25(OH)2D3 (the active form of vitamin D), and subsequently referred to as the KD-VDR&vitD and KD-NC&vitD groups, respectively. Additionally, PTC cells infected with KD-NC and not treated with 1,25(OH)2D3 were used as the normal control and referred to as the KD-NC group. VDR mRNA and protein expression levels were increased in MDA-T120, SNU-790 and MDA-T85 cells compared to Nthy-ori 3-1 cells, whereas in IHH4 cells, VDR mRNA and protein expression levels were similar to Nthy-ori 3-1 cells. In SNU-790 and IHH4 cells, cell proliferation and invasion were decreased in the KD-NC&vitD group compared with the KD-NC group, but increased in the KD-VDR&vitD group compared with the KD-NC&vitD group. Cell apoptosis was increased in the KD-NC&vitD group compared with the KD-NC group, and decreased in the KD-VDR&vitD group compared with the KD-NC&vitD group. Furthermore, the expression levels of Wnt family member 3 and catenin β1 were decreased in the KD-NC&vitD group compared with the KD-NC group, but increased in the KD-VDR&vitD group compared with the KD-NC&vitD group. In conclusion, the present study revealed that VDR-KD attenuated the antiproliferative, pro-apoptotic and anti-invasive effects of vitamin D in PTC by activating the Wnt/β-catenin signaling pathway.

Placenta expression of vitamin D and related genes in pregnant women with gestational diabetes mellitus

Objectives and MethodsA total of 41 GDM and 40 normal glucose tolerance subjects were recruited. Through detecting the level of Serum vitamin D with electrochemical luminescence and vitamin D receptor (VDR) with Enzyme-linked immunosorbent assay (ELISA) in maternal and cord blood, the expression leves of CYP24A1, CYP27B1, VDR protein and mRNA in placenta and umbilical cord with western blotting and RT-PCR, and the DNA methylation levels of CYP24A1 and CYP27B1 gene in placenta with methylation-specific PCR (MSP) and direct bisulfite sequencing (BSP) analysis to explore the potential role of the vitamin D and its related genes in gestational diabetes mellitus (GDM). ResultsSerum vitamin D concentrations were significantly higher in normal pregnant than women with GDM in maternal blood (P < 0.01) and cord blood (P = 0.014). Compared to the control group, the expression levels of CYP24A1 protein (P < 0.01) and mRNA (P = 0.021) and VDR protein (P = 0.026) and mRNA (P = 0.023) in the GDM group were significantly higher in placenta and umbilical cord tissues (P = 0.015, P < 0.01, P = 0.028, P < 0.01, respectively), while that of CYP27B1 protein (P < 0.01) and mRNA (P = 0.042) was significantly lower (P = 0.022, P = 0.032, respectively). Moreover, partial DNA methylation of CYP24A1 and CYP27B1 genes was observed in both GDM and control groups. ConclusionsVitamin D deficiency participates in the pathogenesis of GDM, and changes in the expression of genes related to the vitamin D metabolic pathway are closely related to vitamin D levels in the pregnancy and fetus. However, DNA methylation of CYP24A1 and CYP27B1 might not be involved in the pathogenesis of GDM.

Vitamin D receptor is overexpressed in the duodenum of patients with irritable bowel syndrome.

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, and bile acids are thought to be associated with the pathogenesis of IBS. Bile acid receptors are expressed on intestinal epithelial cells. However, no study has assessed bile acid receptor proteins in IBS. Therefore, we examined the intestinal mucosal expression of bile acid receptors in patients with IBS. Intestinal biopsies were performed in patients with IBS and controls. Mast cells, vitamin D receptor (VDR), and somatostatin were stained with specific antibodies. Levels of VDR, farnesoid X receptor (FXR), takeda-G-protein-receptor-5 (TGR5), claudins, and transient-receptor-potential-cation-channel-subfamily-V-member 6 (TRPV6) were assessed by western blotting. 3Mast cell counts in the second part of the duodenum were significantly higher in patients with IBS than in controls. VDR protein levels were significantly elevated in the duodenum and terminal ileum of patients with IBS compared with controls, although this difference was not seen in the cecum or rectum. FXR and TGR5 protein levels did not differ in any part of the intestine. VDR-positive cryptal epithelia in IBS were distributed not only at basal crypt but also along the upper part of the basal crypt epithelial cells. In contrast, the pattern of gut somatostatin-positive cells, claudins, and TRPV6 levels did not differ. The number of mast cells in the duodenum was significantly increased, and the protein expression levels of VDR, but not those of FXR or TGR5, were elevated in the duodenal epithelial crypt in patients with IBS.

Investigating the Role of Methylation in Silencing of VDR Gene Expression in Normal Cells during Hematopoiesis and in Their Leukemic Counterparts.

(1) Background: Vitamin D receptor (VDR) is present in multiple types of blood cells, and its ligand, 1,25-dihydroxyvitamin D (1,25D), is important for the proper functioning of the immune system. Activity of VDR is higher in hematopoietic stem and progenitor cells than in fully differentiated blood cells of mice and humans. In some human acute myeloid leukemia (AML) blasts, the expression of the VDR gene is also high. The mechanism of silencing the VDR gene expression during differentiation of blood cells has been addressed in this work. (2) Methods: The cells have been obtained using fluorescence activated sorting from murine tissues and from human umbilical cord blood (UCB). Then, the expression of the VDR gene and transcriptional activity of the VDR protein has been tested in real-time polymerase chain reaction (PCR). Eventually, the methylation of VDR promoter regions was tested using bisulfite sequencing. (3) Results: The CpG islands in VDR promoters were not methylated in the cells studied both in mice and in humans. The use of hypomethylating agents had no effect toward expression of human VDR transcripts, but it increased expression of the VDR-target gene, CYP24A1. (4) Conclusions: The expression of the VDR gene and transcriptional activity of the VDR protein varies at successive stages of hematopoietic differentiation in humans and mice, and in blasts from AML patients. The experiments presented in this case indicate that methylation of the promoter region of the VDR gene is not the major mechanism responsible for these differences.

Is there any association between a vitamin D receptor gene polymorphism (FokI) and pemphigus vulgaris

Background Pemphigus vulgaris (PV) is an autoimmune bullous disease of the skin and mucous membranes caused by activation and proliferation of T cells, production of Th2 cytokine profile and pathogenic antibodies. Vitamin D is a probable immunodeviator to Th2, which its actions are mediated through the vitamin D receptor (VDR). FokI is the only single nucleotide polymorphism (SNP) leading to VDR protein with a different structure and function. For the first time, we focused on FokI VDR SNP to evaluate its potential role in the genetic susceptibility to PV, particularly in the Iranian population that has a high prevalence of pemphigus.Methods In this case-control study, DNA samples of 122 PV patients and 233 healthy controls were extracted, and FokI genotyping was performed using the PCR-RFLP method.Results The mean allele frequencies of F and f alleles in the PV and control groups were 75% and 25%, and 78% and 22%, respectively, showing no significant difference. The genotype frequencies for FF, Ff, and ff genotypes in the case group were 57.4%, 35.2%, and 7.4%, respectively. In the control group, the frequencies were 60%, 36%, and 4%, respectively. Statistical analysis showed no significant difference between the two groups.Conclusion The present study concluded the frequencies of F and f alleles as approximately 77% and 23% in the gene pool of the Iranian population. Additionally, it showed no association between the FokI alleles and PV in this population.

The vitamin D receptor Taq I polymorphism is associated with reduced VDR and increased PDIA3 protein levels in human intestinal fibroblasts

The synonymous single nucleotide polymorphism (SNP) rs731236, located in the vitamin D receptor (VDR) gene (Taq I) has been associated with both decreased levels of the protein in peripheral blood mononuclear cells and a fibrosis-related complication in Crohn´s disease (CD). Interactions between VDR and a protein-disulfide isomerase-associated 3 (PDIA3) in the regulation of extracellular matrix have been reported and we aim to analyze the relevance of the VDR genotypes and the effects of Vitamin D (VD) in the expression of VDR, PDIA3 and proliferation of intestinal fibroblasts. Human intestinal fibroblasts were isolated from the non-affected surgical resections of colorectal patients and classified according to the VDR genotype. In some cases, cells were transfected with specific PDIA3 siRNA. Basal and VD-stimulated expression of VDR, PDIA3 and Collagen 1A1 (COL1A1) as well as fibroblast migration/proliferation were analyzed. Our data show that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited lower VDR protein levels and higher proliferation than cells homozygous for the T allele. VD increased VDR and attenuated the accelerated proliferation of CC fibroblasts. The diminished VDR level detected in CC cells was associated with increased levels of both PDIA3 and COL1A1 expression and the transient silencing of PDIA3 significantly reduced COL1A1 expression. We conclude that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited: reduced VDR protein levels, increased proliferation and increased PDIA3/COL1A1 expression. Treatment with VD increased VDR and attenuated proliferation of these cells.

Structural insights on vitamin D receptor and screening of new potent agonist molecules: structure and ligand-based approach

Vitamin D deficiency is one of the common clinical symptoms of severe chronic kidney disease (CKD) patients. Vitamin D receptor (VDR) is a part of the nuclear receptor family exerts vitamin D activation to maintain calcium/phosphorous homeostasis and bone metabolism. The reduction of VDR activity leads to vitamin D deficiency. In this study, we found three potent agonists for VDR protein on the structure and ligand-based screening methods. In the structure-based method, 792 compounds were screened. A 5-point pharmacophore (one hydrogen bond acceptor, two hydrophobic and aromatic rings (AHHRR)) was developed and used to obtain a predictive 3 D-Quantitative structure-activity relationship (QSAR), model. The acquire R2 and Q2 values are 0.8676 and 0.8523 respectively. Further, E-pharmacophore based screening, molecular docking (binding affinity), Molecular Mechanics-Generalized Born Surface Area (binding free energy), chemical reactivity (Density Functional Theory (DFT) study) and molecular dynamics (protein-ligand stability) analysis were done. Hence, the computational investigations demonstrate that the identified ligands such as TCM_1875, TCM_1874, and TCM_2868 showed promising agonist effect on VDR protein. Further validation and experiments need to be done to confirm the potency of the identified compounds shortly. Communicated by Ramaswamy H. Sarma

Regulation of vitamin D system in skeletal muscle and resident myogenic stem cell during development, maturation, and ageing

Skeletal muscle exhibits enormous plasticity throughout life, however, less is known regarding how the stages of growth regulate its local vitamin D system. Herein, we investigated serum 25(OH)D3 and Ca2+ levels along with the vitamin D system in skeletal muscle and resident myogenic stem cells of male C57BL/6 mice during development, maturation, and ageing. Compared with development, significant increases in vitamin D receptor (VDR) protein expression in mature and aged muscles were associated with increased serum 25(OH)D3 and centronucleated fibres, respectively. The substantial increase in VDR protein expression in aged muscle was also related to reduced downstream mTOR signalling protein expression which was more pronounced in fast-glycolytic compared to slow-oxidative muscles. Intriguingly, serum Ca2+ and vitamin D-metabolising enzyme (CYP27B1 and CYP24A1) levels in skeletal muscle were not different across age. In primary cell culture, nuclear VDR protein was expressed in undifferentiated skeletal muscle stem cells (SMSC) after 1α,25(OH)2D3 treatment. Additionally, a diminished response to 1α,25(OH)2D3 was observed with age as there was a rapid commitment of SMSC towards differentiation under growth-stimulating conditions. Collectively, understanding the local vitamin D system in skeletal muscle could help develop effective interventions for vitamin D supplementation to improve skeletal muscle mass and function during ageing.

Vitamin D regulation of HAS2, hyaluronan synthesis and metabolism in triple negative breast cancer cells

The vitamin D receptor (VDR) and its ligand 1,25(OH)2D3 (1,25D) exert anti-tumor effects, but considerable heterogeneity has been reported in different model systems. In general, cell lines derived from aggressive tumor subtypes such as Triple Negative Breast Cancer (TNBC) express low levels of VDR and are less sensitive to 1,25D than those derived from more differentiated tumor types. We have previously reported that 1,25D inhibits hyaluronic acid synthase 2 (HAS2) expression and hyaluronic acid (HA) synthesis in murine TNBC cells. Here we confirmed the inhibitory effect of 1,25D on HA synthesis in human Hs578T cells representative of the mesenchymal/stem-like (MSL) subtype of TNBC. Because HA synthesis requires the production of hexoses for incorporation into HA, we predicted that the high HA production characteristic of Hs578T cells would require sustained metabolic changes through the hexosamine biosynthetic pathway (HBP). We thus examined metabolic gene expression in Hs578T cell variants sorted for High (HAHigh) and Low (HALow) HA production, and the ability of 1,25D to reverse these adaptive changes. HAHigh populations exhibited elevated HA production, smaller size, increased proliferation and higher motility than HALow populations. Despite their more aggressive phenotype, HAHigh populations retained expression of VDR protein at levels comparable to that of parental Hs578T cells and HALow subclones. Treatment with 1,25D decreased production of HA in both HAHigh and HALow populations. We also found that multiple metabolic enzymes were aberrantly expressed in HAHigh cells, especially those involved in glutamine and glucose metabolism. Notably, Glutaminase (GLS), a known oncogene for breast cancer, was strongly upregulated in HAHigh vs. HALow cells and its expression was significantly reduced by 1,25D (100 nM, 24 h). Consistent with this finding, Seahorse extracellular flux analysis indicated that respiration in HAHigh cells was significantly more dependent on exogenous glutamine than HALow cells, however, acute 1,25D exposure did not alter metabolic flux. In contrast to GLS, the glutamate transporter SLC1A7 was significantly reduced in HAHigh cells compared to HALow cells and its expression was enhanced by 1,25D. These findings support the concept that 1,25D can reverse the metabolic gene expression changes associated with HA production in cancer cells with aggressive phenotypes.

Dystrobrevin alpha gene is a direct target of the vitamin D receptor in muscle

The biologically active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (VD3), exerts its tissue-specific actions through binding to its intracellular vitamin D receptor (VDR) which functions as a heterodimer with retinoid X receptor (RXR) to recognize vitamin D response elements (VDRE) and activate target genes. Upregulation of VDR in murine skeletal muscle cells occurs concomitantly with transcriptional regulation of key myogenic factors upon VD3 administration, reinforcing the notion that VD3 exerts beneficial effects on muscle. Herein we elucidated the regulatory role of VD3/VDR axis on the expression of dystrobrevin alpha (DTNA), a member of dystrophin-associated protein complex (DAPC). In C2C12 cells, Dtna and VDR gene and protein expression were upregulated by 1-50 nM of VD3 during all stages of myogenic differentiation. In the dystrophic-derived H2K-mdx52 cells, upregulation of DTNA by VD3 occurred upon co-transfection of VDR and RXR expression vectors. Silencing of MyoD1, an E-box binding myogenic transcription factor, did not alter the VD3-mediated Dtna induction, but Vdr silencing abolished this effect. We also demonstrated that VD3 administration enhanced the muscle-specific Dtna promoter activity in presence of VDR/RXR only. Through site-directed mutagenesis and chromatin immunoprecipitation assays, we have validated a VDRE site in Dtna promoter in myogenic cells. We have thus proved that the positive regulation of Dtna by VD3 observed during in vitro murine myogenic differentiation is VDR mediated and specific. The current study reveals a novel mechanism of VDR-mediated regulation for Dtna, which may be positively explored in treatments aiming to stabilize the DAPC in musculoskeletal diseases.

Nutraceuticals Derived From Pomegranate Selectively Enhance Vitamin D Receptor Signaling to Amplify Key Vitamin D Target Genes

The active vitamin D hormone, 1,25‐dihydroxyvitamin D (1,25D), mediates its biological effects by binding to the nuclear vitamin D receptor (VDR) and promoting heterodimerization with retinoid X receptors (RXRs). Various nutraceuticals, including resveratrol and curcumin, have been postulated to interact with the vitamin D signaling pathway. More recently, health benefits attributed to pomegranate have been associated with its high content of polyphenols, specifically ellagitannins, which are metabolized by the gut microbiota to produce Urolithin A (UA). In this study, we investigated the ability of UA to modulate 1,25D signaling via transcription and qPCR assays. We hypothesized that 1,25D in combination with urolithin will stimulate VDR activity more than 1,25D alone, increasing transcription of 1,25D target genes. The increased activation of anti‐oxidation genes by 1,25D and UA could help combat reactive oxygen species and attenuate cellular “aging”. Our results indicate that there is a significant increase in VDR transcriptional activity when HEK‐293 kidney cells are treated with UA in conjunction with 1,25D at several 1,25D andUA concentrations. A similar effect was also observed using three structurally‐distinct 1,25D response elements. The potentiation of VDR activity via UA retains receptor‐selectivity since UA did not promote further activation of other receptor‐ligand complexes including estrogen‐ER, rexinoid‐RXR and TO‐LXR. Finally, amplification of serotonin production in brain cells was greatest with a combined cocktail of 1,25D/UA/resveratrol via qPCR (TPH2 gene) and ELISA (5‐HT). In order to probe the molecular mechanism of UA amplification in VDR activity, we tested VDR‐RXR heterodimerization and observed no effect of UA. However, UA activates AMP‐kinase, and we found potential AMP kinase phosphorylation consensus sites in the VDR protein sequence. Collectively, our novel results position gut microbiota‐derived UA as a putative VDR modulator, suggesting that the influences of 1,25D and UA converging on VDR may potentially mediate anti‐aging and promote longevity.Support or Funding InformationFinancial support/grant sponsor: National Institutes of Health; grant numbers: DK033351 and CA140285

Diminished Vitamin D Receptor Protein Levels in Crohn's Disease Fibroblasts: Effects of Vitamin D.

Vitamin D (VD) deficiency has been associated to Crohn’s disease (CD) pathogenesis, and the exogenous administration of VD improves the course of the disease, but the mechanistic basis of these observations remains unknown. Vitamin D receptor (VDR) mediates most of the biological functions of this hormone, and we aim to analyze here the expression of VDR in intestinal tissue, epithelial cells, and fibroblasts from CD patients. The effects of VD on a fibroblast wound healing assay and murine intestinal fibrosis are also analyzed. Our data show diminished VDR protein levels in surgical resections and epithelial cells from CD patients. In intestinal fibroblasts isolated from damaged tissue of CD patients, we detected enhanced migration and decreased VDR expression compared with both fibroblasts from non-damaged tissue of the same CD patient or control fibroblasts. Treatment with VD increased VDR protein levels, avoided the accelerated migration in CD fibroblasts, and prevented murine intestinal fibrosis induced by the heterotopic transplant model. In conclusion, our study demonstrates diminished VDR protein levels associated with enhanced migration in intestinal fibroblasts from damaged tissue of CD patients. In these cells, VD accumulates VDR and normalizes migration, which supports that CD patients would benefit from the VD anti-fibrotic therapeutic value that we demonstrate in a murine experimental model.

Characterization of VDR and CYP27B1 expression in the endometrium during the menstrual cycle before embryo transfer: implications for endometrial receptivity

BackgroundMolecular analyses of vitamin D in a typical cycling endometrium has received minimal research attention in the reproductive field. This study was designed to assess how expression of the endometrial vitamin D receptor (VDR) and CYP27B1, a vitamin D metabolizing enzyme, change during the menstrual cycle in women of reproductive age. In addition, this study explores the association between expression of vitamin D-VDR system and endometrial receptivity during the implantation window.MethodsSixteen patients underwent standardized in vitro fertilization (IVF) treatment and freeze-all techniques. Before embryo transfer, total serum 25(OH) D levels were determined through blood samples and VDR, CYP27B1, HOXA10, and CYP19 expression were determined through endometrial samples. Endometrial receptivity was also assessed using an electron microscope.ResultsWe found that VDR protein expression was significantly lower throughout the endometrial secretory phase compared to the proliferative phase, while CYP27B1 expression remained constant during the menstrual cycle. During the implantation window, ultrastructural evaluation showed that higher serum vitamin D levels were associated with more mature pinopodes; VDR and HOXA10 protein expression were substantially elevated in pregnant women compared to non-pregnant women; and VDR protein levels were positively correlated with HOXA10 levels. In addition, serum vitamin D levels were positively correlated with VDR and HOXA10 protein levels in the endometrium.ConclusionsWomen with increased VDR expression in the endometrium, especially during the implantation window of the menstrual cycle, were significantly more likely to be pregnant than women with decreased expression. Our results support the hypothesis that the Vitamin D-VDR system performs a role during the development of endometrial receptivity.

Vitamin D receptor and monocyte chemoattractant protein-1 expressions in peripheral blood mononuclear cells in patients with systemic lupus erythemaotsus

To detect the expressions of vitamin D receptor (VDR) in peripheral blood monocytes (PBMCs) and its association with monocyte chemoattractant protein-1 (MCP-1) in patients with systemic lupus erythemaotsus (SLE). We examined the expressions of VDR and MCP-1 mRNAs in the PBMCs in 60 SLE patients and 28 healthy individuals using real- time quantitative PCR. We also detected the expression of VDR protein in the PBMCs using Western blotting and peripheral blood MCP-1 level using ELISA for these participants. The correlation of VDR and MCP-1 expressions with the disease activity index of SLE (SLEDAI) of the patients were analyzed. The expressions of VDR mRNA and protein in the PBMCs were significantly lower in patients with SLE than in the healthy individuals (P < 0.01), and that in the patients with active disease was lower than in remission (P < 0.05). The MCP-1 mRNA expression in the PBMCs and its serum levels were significantly increased in SLE patients as compared with the healthy individuals (P < 0.01), and the increase was significantly more obvious in the patients with active disease than in those in remission (P < 0.01). Pearson correlation analysis showed that VDR mRNA in the PBMCs was negatively correlated with SLEDAI (r=-0.417, P=0.001); negative correlations were also found between VDR mRNA and MCP-1 mRNA(r=-0.554, P=0.000) and between VDR protein expression and serum MCP-1 level (r=-0.400, P=0.028). The down-regulation of VDR expression in the PBMC is negatively correlated with the disease activity of SLE. VDR may play an important role in the pathogenesis of SLE by affecting the expression of MCP-1.