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Isolation of genomic DNA sequences that bind vitamin D receptor complexes
N J Koszewski1, S Kiessling, H H Malluche
1Division of Nephrology, Bone and Mineral Metabolism, University of Kentucky Medical Center, Lexington 40536-0298, USA. njhosz0@pop.uky.edu
Biochemical and Biophysical Research Communications
|April 27, 2001
Summary
Researchers identified novel genomic binding sites for the vitamin D receptor (VDR). This discovery aids in understanding how VDR regulates genes, advancing research on vitamin D signaling pathways.
Area of Science:
- Molecular Biology
- Genetics
- Endocrinology
Background:
- Vitamin D signaling relies on the vitamin D receptor (VDR) binding to DNA.
- VDR typically forms heterodimers with retinoid X receptor alpha (RXRα) to bind vitamin D response elements (VDREs).
- Recent evidence suggests VDR may recognize diverse binding sites, including those for homodimers.
Purpose of the Study:
- To investigate the flexibility of VDR binding sites within genomic DNA.
- To identify novel DNA sequences recognized by VDR.
- To characterize the functional activity of newly identified VDR binding sites.
Main Methods:
- Utilized immunoselection and PCR amplification to screen for VDR genomic binding sites.
- Analyzed isolated DNA fragments for VDR complex formation with recombinant human VDR (rhVDR) and rhRXRα.
- Assessed functional activity using luciferase reporter assays and DNaseI footprinting.
Main Results:
- Successfully isolated four unique DNA fragments that bind VDR.
- Demonstrated that these fragments form specific VDR complexes, alone or with rhRXRα.
- Two fragments showed hormone-dependent repression of gene activity and specific binding over DR+3 half-site sequences.
Conclusions:
- Specific, functional VDR binding sites can be isolated from genomic DNA.
- This method facilitates the discovery of genes regulated by VDR.
- Findings expand understanding of VDR's recognition capabilities and gene regulation.