Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Analysis of vitamin D response element binding protein target genes reveals a role for vitamin D in osteoblast mTOR signaling

ABSTRACT: Heterogeneous nuclear ribonucleoprotein (hnRNP) C1/C2 plays a pivotal role in vitamin D receptor (VDR) signaling by acting as a vitamin D response element (VDRE)-binding protein (VDRE-BP). Transcriptional regulation by active 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) involves occupancy of VDRE by VDRE-BP or 1,25(OH)2D3 bound-VDR. This relationship is disrupted by over-expression of VDRE-BP and can cause a form of human hereditary vitamin D-resistant rickets (HVDRR). DNA array analyses using B-cells from an HVDRR patient and matched control defined a sub-cluster of genes where 1,25(OH)2D3-regulated transcription was abrogated by over-expression of VDRE-BP. Amongst these, the DNA-damage-inducible transcript 4 (DDIT4), an inhibitor of mammalian target of rapamycin (mTOR) signaling, was also induced by 1,25(OH)2D3 in human osteoblasts. Chromatin immunoprecipitation using 1,25(OH)2D3-treated osteoblasts confirmed that liganded VDR and VDRE-BP compete for binding to the proximal promoter of the DDIT4 gene in a similar fashion to other known 1,25(OH)2D3-target genes. Treatment of osteoblasts with 1,25(OH)2D3 induced DDIT4 expression and suppressed phosphorylated S6K1T389 protein (a downstream target of mTOR). The functional importance of this for 1,25(OH)2D3 responses in osteoblasts was underlined by the fact that siRNA knockdown of DDIT4 expression suppressed antiproliferative and cell growth responses to 1,25(OH)2D3. These data confirm that VDRE-BP is required for normal 1,25(OH)2D3-mediated transcription and cell function in osteoblasts. Conversely over-expression of VDRE-BP exerts a dominant-negative effect on transcription of 1,25(OH)2D3-target genes. Characterization of VDRE-BP action in 1,25(OH)2D3-treated osteoblasts highlights an entirely novel role for vitamin D as a regulator of mTOR – a known ‘master regulator’ of cell function. We performed gene expression microarray analysis in HVDRR EBV-transformed B-cells and control cells in the presence or absence of vitamin D.

ORGANISM(S): Homo sapiens

SUBMITTER: Thomas Lisse

PROVIDER: E-GEOD-22523 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

ACCESS DATA

Similar Datasets

Project description:We investigated how the biologically active form of vitamin D (1,25(OH)2D3) inhibits the epithelial-to-mesenchymal transition (EMT), a critical step in the development of a migratory phenotype in epithelial tumor cells, as well as migration in general, using osteosarcoma (OS) as a model. We looked at how 1,25(OH)2D3 affected pre- and post-EMT migratory states in non-metastatic MG63 and metastatic LM7 OS cell models. In scratch and Boyden chamber assays, 1,25(OH)2D3 inhibited cell migration and invasion, but LM7 cells responded significantly less than MG63 cells (50 vs 26 percent decrease, respectively). 1,25(OH)2D3 inhibited the expression of EMT-inducing genes (e.g., SNAI2) and extracellular contact regulatory genes in MG63 cells but not in LM7 cells (e.g., CD44, MMP3). In comparison to MG63 cells, LM7 cells had significantly lower baseline VDR transcript levels but higher SNAI2 transcript levels. Furthermore, ATAC-seq analysis revealed that 1,25(OH)2D3 epigenetically repressed SNAI2 in MG63 cells, implying that LM7 cells may be constitutively induced to undergo EMT via VDR de-repression mediated by increased SNAI2 levels. Both cell lines appeared to activate an antioxidative pathway involving SOD2 upregulation and concurrent reactive oxygen species (ROS) reduction (e.g., H2O2). ATAC-seq analysis revealed that 1,25(OH)2D3 does not epigenetically regulate SOD2 in MG63 cells, implying a previously unknown indirect link promoting anti-EMT and anti-metastatic oxidation states in both OS cell lines. We studied the fate and migration of mouse hair follicle stem cell progenitor cells after wounding with or without the Vdr because cutaneous wounding and metastasis involve similar signaling factors that regulate cell migration. Conditional loss of Vdr in epithelial progenitor cells promoted cell migration and wound healing in comparison to control animals, indicating that Vdr signaling inhibits cell migration in general. Our findings show that vitamin D signaling inhibits cell migration both in vivo and in vitro, and that inhibiting reactive oxygen species (ROS) in both pre-EMT and post-EMT OS cells is a possible vitamin D mechanism and therapeutic strategy for preventing the onset and progression of OS. MG63 human osteosarcoma cell line treated with vehicle (ethanol) or 1,25(OH)D (10nM) for 24 and 48 hours.

Dataset Information

Analysis of vitamin D response element binding protein target genes reveals a role for vitamin D in osteoblast mTOR signaling

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets