Project description:Mutations of the lamin A/C gene (LMNA) cause a variety of diseases including dilated cardiomyopathy (DCM). LMNA-related DCM often leads to severe heart failure, but the underlying pathophysiology is unknown. Here we show that vitamin D receptor (VDR) signaling is critically involved in LMNA-related DCM. We established iPS cells from DCM patients with an LMNA mutation and found that the iPS cell-derived cardiomyocytes (iPSCMs) showed remarkable DNA damage and reduced contractility compared with the isogenic control. Screening of a chemical library revealed that vitamin D2 reduced DNA damage of the mutant iPSCMs. RNA sequencing analysis showed that expression levels of putative downstream genes of VDR including DNA repair factors were downregulated in the mutant iPSCMs, which were upregulated by vitamin D2. Protein-protein interaction screening revealed that the binding of VDR to mutant LMNA was more robust than to wild-type LMNA, resulting in attenuated VDR signaling in the mutant iPSCMs. Vitamin D2 administration reduced DNA damage and improved cardiac function in pressure overload-induced heart failure mice. These results indicate that impaired DNA repair caused by reduced transcriptional activity of VDR induces cardiac dysfunction of LMNA-related DCM and suggest that VDR signaling is a potential therapeutic target for patients with DCM and heart failure.
Project description:Vitamin D deficiency and mutations in Vitamin D Receptor (VDR) are associated with liver disease and obesity, but the functions of vitamin D signaling in metabolism are poorly understood. Though vitamin D signaling is best known for its functions in mineral homeostasis and skeleton calcification in terrestrial vertebrates, this is unlikely to be the evolutionary function of vitamin D signaling. We utilize tissue-specific genetic modulation of Vdr signaling to investigate the function of the vitamin D endocrine system in zebrafish. We find that hepatocyte Vdr regulates organismal response to nutritional cues and coordinates hepatic and organismal energy metabolism by balancing energy storage and tissue growth.
Project description:Complex autoimmune diseases have proven difficult to dissect down to their causative genetic mechanisms. As a result, epidemiological data from different human association studies are often merged to arrive at a working hypothesis. In one of such examples, lack of sun exposure and consequent lower serum vitamin D3 levels has been proposed to increase risk of autoimmunity, attributing vitamin D3 an immune regulatory role. However, conclusive evidence demonstrating its efficacy in treating autoimmune diseases is missing. In this study, we have used a forward genetics approach to positionally identify polymorphic nucleotides controlling T cell-dependent inflammatory diseases using congenic mouse strains. Here, we identify the vitamin D3 receptor (Vdr) as a driver of inflammation. Congenic mice carrying a polymorphic Vdr allele overexpressed the receptor selectively in activated T cells, thereby escaping systemic calcaemic side effects that often constitute a confounding factor in the study of immunomodulation by vitamin D3. Mice overexpressing Vdr in T cells developed more severe collagen-induced arthritis (CIA) and exhibited an enhanced antigen-specific CD4+ T cell response. Deficiency of vitamin D3 completely protected mice from CIA by limiting the activation of antigen-specific T cell responses, and arthritis susceptibility was restored by re-administration of vitamin D3. We demonstrate that vitamin D3 signalling specifically through Vdr predominantly acts to enhance T cell proliferation, thereby contributing to inflammation. In conclusion, our results demonstrate that genetically determined expression of VDR codetermines the pro-inflammatory behaviour of activated T cells. Furthermore, our data suggest that the anti-inflammatory properties of vitamin D3 might be limited by high expression of VDR at the site of inflammation.
Project description:We investigated the genomic activity of vitamin D in primary prostate epithelial cells (PrE) through vitamin D receptor (VDR)-ChIP-sequencing. PrE cells treated with 50 nM 1,25D showed nuclear localization the VDR within 1 hr, persisting until 4 hr, and a 2 hr treatment was selected for ChIP-seq. Rigorous testing of the ChIP conditions and VDR antibody were performed. Nearly 5,000 VDR binding sites were identified.
Project description:Identification of primary target genes of vitamin D receptor (VDR) in an immune-related cellular model (THP-1 cells) to study, in conjunction with VDR binding data from ChIP-seq, the genome-wide mechanisms of transcriptional regulation by VDR.
Project description:Identification of primary target genes of vitamin D receptor (VDR) in an immune-related cellular model (THP-1 cells) to study, in conjunction with VDR binding data from ChIP-seq, the genome-wide mechanisms of transcriptional regulation by VDR. THP-1 cells were treated 4 h either with 0.1% ethanol (vehicle, control) or 1?,25(OH)2D3 (1,25D)
Project description:Vitamin D3 metabolites are capable of controlling gene expression in mammalian cells through two independent pathways: vitamin D receptor (VDR) and sterol regulatory element-binding protein (SREBP) pathways. In the present study, we dissect the complex biological activity of vitamin D by designing synthetic vitamin D3 analogs specific for VDR or SREBP pathway, i.e., a VDR activator that lacks SREBP inhibitory activity, or an SREBP inhibitor devoid of VDR activity.