GSBS Student Publications

Title

Vitamin D-responsive protein-DNA interactions at multiple promoter regulatory elements that contribute to the level of rat osteocalcin gene expression

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Medicine, Diabetes Division; Department of Cell Biology

Date

7-1-1992

Document Type

Article

Medical Subject Headings

Animals; Base Sequence; DNA-Binding Proteins; *Gene Expression Regulation; Macromolecular Substances; Molecular Sequence Data; Osteocalcin; Osteosarcoma; *Promoter Regions (Genetics); Rats; Receptors, Calcitriol; Receptors, Steroid; Regulatory Sequences, Nucleic Acid; TATA Box; Tumor Cells, Cultured; Vitamin D

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The observation that vitamin D-mediated enhancement of osteocalcin (OC) gene expression is dependent on and reciprocally related to the level of basal gene expression suggests that an interaction of the vitamin D responsive element (VDRE) with basal regulatory elements of the OC gene promoter contributes to both basal and vitamin D-enhanced transcription. Protein-DNA interactions at the VDRE of the rat OC gene (nucleotides -466 to -437) are reflected by direct sequence-specific and antibody-sensitive binding of the endogenous vitamin D receptor present in ROS 17/2.8 osteosarcoma nuclear protein extracts. In addition, a vitamin D-responsive increase in OC gene transcription is accompanied by enhanced non-vitamin D receptor-mediated protein-DNA interactions in the "TATA" box region (nucleotides -44 to +23), which also contains a potential glucocorticoid responsive element. Evidence for proximity of the VDRE with the basal regulatory elements is provided by two features of nuclear architecture. (i) Nuclear matrix attachment elements in the rat OC gene promoter that bind nuclear matrix proteins with sequence specificity may impose structural constraints on promoter conformation. (ii) Limited micrococcal nuclease digestion and Southern blot analysis indicate that three nucleosomes can be accommodated in the sequence spanning the OC gene VDRE, the OC/CCAAT box (nucleotides -99 to -76), and the TATA/glucocorticoid responsive element, and thereby the potential distance between the VDRE and the basal regulatory elements can be reduced. A model is presented for the contribution of both the VDRE and proximal promoter elements to the enhancement of OC gene transcription in response to vitamin D. The vitamin D receptor plus accessory proteins may function cooperatively with basal regulatory factors to modulate the extent to which the OC gene is transcribed.

Rights and Permissions

Citation: Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):6119-23.

Related Resources

Link to article in PubMed

Journal Title

Proceedings of the National Academy of Sciences of the United States of America

PubMed ID

1321435