A central dinucleotide within vitamin D response elements modulates DNA binding and transactivation by the vitamin D receptor in cellular response to natural and synthetic ligands
Graduate School of Biomedical Sciences; Department of Internal Medicine; Department of Cell Biology
Life Sciences | Medicine and Health Sciences
There is considerable divergence in the sequences of steroid receptor response elements, including the vitamin D response elements (VDREs). Two major VDRE-containing and thus 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3))-regulated genes are the two non-collagenous, osteoblast-derived bone matrix proteins osteocalcin and osteopontin. We observed a stronger induction of osteopontin than osteocalcin mRNA expression by 1,25-(OH)(2)D(3). Subsequently, we have shown that vitamin D receptor/retinoid X receptor alpha (VDR/RXRalpha) heterodimers bind more tightly to the osteopontin VDRE than to the osteocalcin VDRE. Studies using point mutants revealed that the internal dinucleotide at positions 3 and 4 of the proximal steroid half-element are most important for modulating the strength of receptor binding. In addition, studies with VDRE-driven luciferase reporter gene constructs revealed that the central dinucleotide influences the transactivation potential of VDR/RXRalpha with the same order of magnitude as that observed in the DNA binding studies. The synthetic vitamin D analog KH1060 is a more potent stimulator of transcription and inducer of VDRE binding of VDR/RXR in the presence of nuclear factors isolated from ROS 17/2.8 osteoblast-like cells than the natural ligand 1,25-(OH)(2)D(3). Interestingly, however, KH1060 is comparable or even less potent than 1,25-(OH)(2)D(3) in stimulating VDRE binding of in vitro synthesized VDR/RXRalpha. Thus, the extent of 1,25-(OH)(2)D(3)- and KH1060-dependent binding of VDR/RXRalpha is specified by a central dinucleotide in the VDRE, and the ligand-induced effects on DNA binding are in part controlled by the cellular context of nuclear proteins.
DOI of Published Version
J Biol Chem. 2002 Apr 26;277(17):14539-46. Epub 2002 Feb 7. Link to article on publisher's site
The Journal of biological chemistry
van den Bemd GC, Jhamai M, Staal A, Van Wijnen AJ, Lian JB, Stein GS, Pols HA, van Leeuwen JP. (2002). A central dinucleotide within vitamin D response elements modulates DNA binding and transactivation by the vitamin D receptor in cellular response to natural and synthetic ligands. GSBS Student Publications. https://doi.org/10.1074/jbc.M111224200. Retrieved from https://escholarship.umassmed.edu/gsbs_sp/1278