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PubMed2024

The association between vitamin D receptor gene polymorphism FokI and type 2 diabetic kidney disease and its molecular mechanism: a case control study.

BACKGROUND: The role of the vitamin D receptor single nucleotide polymorphism FOKI (VDR-FOKI) (rs2228570) in genetic susceptibility to type 2 diabetic kidney disease (T2DKD) remains uncertain. This study investigated the relationship between VDR-FOKI and T2DKD within the Chinese Plateau Han population and analyzed the underlying mechanisms. METHODS: A total of 316 subjects were enrolled, including 44 healthy adults, 114 individuals with type 2 diabetes mellitus (T2DM), and 158 patients with T2DKD. According to the 2023 American Diabetes Association Diabetes Guidelines, patients with T2DKD were categorized into low-medium-risk and high-risk groups based on estimates of glomerular filtration rate and urinary albumin-to-creatinine ratio. The VDR-FokI genotypes of all participants were identified using the Taqman probe and classified as homozygous mutant genotypes (C/C or FF), heterozygous mutant genotypes (C/T or Ff), and homozygous wild genotypes (T/T or ff). Plasma levels of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase activity (SOD) were assessed in T2DKD patients with FF and ff genotypes. Additionally, the levels of plasma VDR, GPX4, and P53 were determined using ELISA, while the relative expressions of VDR mRNA, GPX4 mRNA, and TP53 mRNA in whole blood were measured by RT-qPCR. RESULTS: The T2DM patients with the ff genotype exhibited a 2.93-fold increased likelihood of developing T2DKD compared to those with the FF genotype (ORadjusted = 2.93; 95% CI: 1.142-7.513). Additionally, they were 2.01 times more likely to develop T2DKD than individuals with the FF and Ff genotypes (ORadjusted = 2.01; 95% CI: 1.008-4.006). However, no significant differences in VDR-FokI genotype distribution were observed between the healthy control group and the T2DM group, as well as between the low-medium-risk and high-risk groups of T2DKD. Furthermore, T2DKD patients with the ff genotype had significantly higher plasma levels of MDA compared to those with the FF genotype. In contrast, plasma GSH and SOD content was significantly lower in the ff genotype patients (P < 0.05). Additionally, the GPX4 concentration in ff genotype patients was significantly lower than in FF genotype patients [14.88 (11.32,22.39) vs. 12.76 (8.55,13.75), P = 0.037]. Nevertheless, no statistically significant difference was observed in the expression of VDRmRNA, GPX4mRNA, TP53mRNA, plasma VDR, and plasma P53. CONCLUSIONS: The ff genotype of VDR-FokI is a risk factor for T2DKD, and the potential mechanism may be related to ferroptosis. However, It is not associated with T2DM or the progression of T2DKD.

Humans↗

PubMed2026

Evaluating Associations Between Ankylosing Spondylitis, Torque Teno Virus and Polymorphisms in Interleukin 6 and Vitamin D Receptor Genes.

The etiology of ankylosing spondylitis (AS) is complex and not yet fully understood. Interleukin-6 (IL-6), vitamin D and the vitamin D receptor (VDR) play an important role in modulating immune response, and Torque teno virus is considered a marker of immune status. This case-control study aimed to investigate the predisposition to AS. A total of 85 patients with AS and 100 clinically healthy individuals were included. VDR polymorphisms (rs2228570, rs1544410, rs7975232, rs731236) were genotyped using the PCR-RFLP technique, while for the IL-6 -174 G>C (rs1800795) polymorphism the tetra-primer ARMS-PCR technique was used. The presence of TTV was detected using the hemi-nested PCR technique. Our findings indicate a statistically significant association between TTV and AS (p = 0.035). C allele of both rs1800795 polymorphism in main groups (p = 0.027) and rs731236 polymorphism in women subgroups (p = 0.036) may be linked to an increased susceptibility to AS. However, none of these associations reach statistical significance after Bonferroni correction. Furthermore, within female subgroups, a significant association was found between the T allele of rs1544410 polymorphism and AS (p = 0.000038, corrected p = 0.00076). A significant association was also observed between the TT genotype of rs2228570 polymorphism, TTV and AS (p = 0.029). Haplotype analysis revealed that certain VDR haplotypes may confer either a protective effect against AS or an increased risk of developing the condition. Notably, rs1544410 polymorphism or a linked polymorphism may influence AS susceptibility. In conclusion, our data suggest that TTV and VDR polymorphisms may be associated with an increased risk of developing AS, indicating that these markers could potentially be used in the future for earlier diagnosis and more targeted treatment of the disease.

Torque teno virus↗

PubMed2003

Regulation of the bone-specific osteocalcin gene by p300 requires Runx2/Cbfa1 and the vitamin D3 receptor but not p300 intrinsic histone acetyltransferase activity.

p300 is a multifunctional transcriptional coactivator that serves as an adapter for several transcription factors including nuclear steroid hormone receptors. p300 possesses an intrinsic histone acetyltransferase (HAT) activity that may be critical for promoting steroid-dependent transcriptional activation. In osteoblastic cells, transcription of the bone-specific osteocalcin (OC) gene is principally regulated by the Runx2/Cbfa1 transcription factor and is stimulated in response to vitamin D(3) via the vitamin D(3) receptor complex. Therefore, we addressed p300 control of basal and vitamin D(3)-enhanced activity of the OC promoter. We find that transient overexpression of p300 results in a significant dose-dependent increase of both basal and vitamin D(3)-stimulated OC gene activity. This stimulatory effect requires intact Runx2/Cbfa1 binding sites and the vitamin D-responsive element. In addition, by coimmunoprecipitation, we show that the endogenous Runx2/Cbfa1 and p300 proteins are components of the same complexes within osteoblastic cells under physiological concentrations. We also demonstrate by chromatin immunoprecipitation assays that p300, Runx2/Cbfa1, and 1alpha,25-dihydroxyvitamin D(3) receptor interact with the OC promoter in intact osteoblastic cells expressing this gene. The effect of p300 on the OC promoter is independent of its intrinsic HAT activity, as a HAT-deficient p300 mutant protein up-regulates expression and cooperates with P/CAF to the same extent as the wild-type p300. On the basis of these results, we propose that p300 interacts with key transcriptional regulators of the OC gene and bridges distal and proximal OC promoter sequences to facilitate responsiveness to vitamin D(3).

Acetyltransferases↗

PubMed2024

In vivo vitamin D target genes interconnect key signaling pathways of innate immunity.

The vitamin D3 metabolite 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), its nuclear receptor VDR (vitamin D receptor) and hundreds of their target genes are not only key regulators of calcium homeostasis, but also important modulators of the immune system. Innate immune cells like monocytes use VDR for efficient differentiation and are very responsive to vitamin D. So far, most information on the gene regulatory function of vitamin D and its physiological impact had been obtained from in vitro studies using supraphysiological doses of 1,25(OH)2D3. Therefore, medical experiments like the study VitDHiD (NCT03537027), where 25 healthy individuals were supplemented once with a vitamin D3 bolus (80,000 IU), provide important insight into the response to vitamin D under in vivo conditions. In this study, we inspected 452 in vivo vitamin D target genes from peripheral blood mononuclear cells (PBMCs) detected in VitDHiD and found 61 of them involved in eight major KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways of innate immunity. Under in vivo conditions in healthy individuals vitamin D either silences five pathways of innate immunity, stabilizes two and increases one, so that acute inflammation is suppressed and the release of cytokines is kept under control. A ranking of the 61 target genes by inducibility, basal expression and multiple involvements in the pathways highlighted the genes NFKBIA (NFκB inhibitor alpha), NFKBIZ, FOSL2 (FOS like 2, AP1 transcription factor subunit), JDP2 (Jun dimerization protein 2), PIK3R1 (phosphoinositide-3-kinase regulatory subunit 1), CLEC7A (C-type lectin domain containing 7A), DUSP6 (dual specificity phosphatase 6), NCF2 (neutrophil cytosolic factor 2), PLCB1 (phospholipase C beta 1), PLCG2 and TNFAIP3 (TNF alpha induced protein 3). In conclusion, vitamin D's in vivo effect on innate immunity in healthy adults is mediated by the interconnection of the pathways of neutrophil extracellular trap formation, Toll-like receptor, chemokine and phagosome signaling, NOD-like receptor, C-type lectin receptor, apoptosis and interleukin 17 through a limited set of proteins encoded by key target genes.

Humans↗

PubMed2026

Genome-wide chromatin profiling reveals a nonlimiting role for RXR in macrophage-like cells stimulated with multiple nuclear receptor agonists.

Retinoid X receptor (RXR) is an obligate heterodimerization partner for many nuclear receptors. In the absence of ligands, RXR occupies thousands of genomic regions, with its binding landscape predominantly determined by cell identity. In the presence of agonists of RXR or its partners, RXR occupancy is changed at a subset of binding regions. The characteristics of these ligand-responsive binding regions remain largely unexplored. We used ChIP-seq to profile RXR occupancy in PMA-differentiated THP-1 cells treated with agonists of RXR or partner receptors, including RARα, VDR, PPARδ, PPARγ, LXRs, and TR, or a "cocktail" containing multiple agonists. The RXR agonist LG268 produced a stronger increase in RXR occupancy than any of the six partner-receptor agonists or their combination. The relevance of ligand-induced RXR peaks was confirmed by the analyses of motif enrichment and RXR occupancy at regulatory elements of target genes. RXR binding was investigated in more detail in cells treated with the VDR agonist, calcitriol. Calcitriol markedly enhanced VDR binding, but the corresponding increase in RXR occupancy was less pronounced. We found that both ligand-induced and unresponsive RXR peaks were involved in gene regulation, and only a small subset (∼3%) of calcitriol-regulated genes exhibited decreases in both RXR binding and mRNA levels in response to combined agonist treatment. These results support a model in which RXR functions as a nonlimiting module in a macrophage-like cell type, and interference between pathways is minimally attributable to RXR sequestration.

Humans↗

PubMed2025

Transcriptomic profile induced by calcitriol in CaSki human cervical cancer cell line.

The vitamin D endocrine system, primarily mediated by its main metabolite calcitriol and the vitamin D receptor (VDR), plays a critical role in numerous human physiological processes, ranging from calcium metabolism to the prevention of various tumors, including cervical cancer. In this study, we comprehensively investigated the genomic regulatory effects of calcitriol in a cervical cancer model. We examined the transcriptional changes induced by calcitriol in CaSki cells, a cervical cell line harboring multiple copies of HPV16, the primary causal agent of cervical cancer. Our microarray findings, revealed that calcitriol regulated over 1000 protein-coding genes, exhibiting a predominantly repressive effect on the CaSki cell transcriptome by suppressing twice as many genes as it induced. Calcitriol decreased EPHA2 and RARA expression while inducing KLK6 and CYP4F3 expression in CaSki cells, as validated by qPCR and Western blot. Functional analysis demonstrated that calcitriol effectively inhibited key processes involved in cancer progression, including cell proliferation and migration. This was further supported by the significant downregulation of MMP7 and MMP13 mRNA levels. Our microarray results also showed that, in addition to its effects on protein-coding genes, calcitriol significantly regulates non-coding RNAs, altering the expression of approximately 400 non-coding RNAs, including 111 microRNA precursors and 29 mature microRNAs, of which 17 were upregulated and 12 downregulated. Notably, among these calcitriol-regulated microRNAs are some involved in cervical cancer biology, such as miR-6129, miR-382, miR-655, miR-211, miR-590, miR-130a, miR-301a, and miR-1252. Collectively, these findings suggest that calcitriol exhibits a significant antitumor effect in this advanced cervical cancer model by blocking critical processes for tumor progression, underscoring the importance of maintaining adequate vitamin D nutritional status.

Humans↗

PubMed1979

Interaction of 1 alpha, 24-dihydroxyvitamin D3 with the chick intestinal 1 alpha, 25-dihydroxyvitamin D3 receptor system.

The interaction of 1 alpha, 24-dihydroxyvitamin D3 with the 1 alpha, 25-dihydroxyvitamin D3 receptor system was studied in chick intestinal mucosa. The competitive receptor binding assay indicated that 1 alpha, 24-dihydroxyvitamin D3 bound to a cytosol 1 alpha, 25-dihydroxyvitamin D3 receptor with a relatively high affinity compared with other vitamin D3 analogs. The R-isomer of 1 alpha, 24-dihydroxyvitamin D3 revealed higher affinity for the receptor than the S-isomer. In the reconstituted cytosol-chromatin system, bith 1 alpha, 24(R)-dihydroxy[3H]-vitamin D3 and 1 alpha, 24(S)-dihydroxy-[3H]-vitamin D3 specifically associated with chromatin via a temperature-dependent process. The association of 1 alpha, 24-dihydroxy-[3H]-vitamin D3 with chromatin was reduced in the presence of competing unlabeled 1 alpha, 25-dihydroxyvitamin D3. Furthermore, the chromatin-associated 1 alpha, 24-dihydroxy-[3H]-vitamin D3 was dissociated by a high concentration of KCl, likewise 1 alpha, 25-dihydroxy-[3H]-vitamin D3. From these results, it is strongly indicated that 1 alpha, 24-dihydroxyvitaim D3 is recognized by cytosol 1 alpha, 25-dihydroxyvitamin D3 receptor as an analog of 1 alpha, 25-dihydroxyvitamin D3 and associates with chromatin by the same mechanism as 1 alpha, 25-dihydroxyvitamin D3.

Animals↗