In vivo occupancy of the vitamin D responsive element in the osteocalcin gene supports vitamin D-dependent transcriptional upregulation in intact cells.
The steroid hormone vitamin D is a principal mediator of skeletal homeostasis. 1,25-Dihydroxyvitamin D3 treatment of ROS 17/2.8 osteoblast-like cells results in a ligand-dependent increase in transcription of the bone-specific osteocalcin gene. This transcriptional upregulation requires the positive cis-acting vitamin D responsive element (VDRE). We have used the ligation-mediated polymerase chain reaction to demonstrate that protein occupancy of the VDRE within the intact cell correlates with increased synthesis of osteocalcin transcripts. These protein-DNA contacts were not present in the absence of vitamin D or in osteosarcoma cells (ROS 24.1) lacking the vitamin D receptor. Our results establish in intact cells the requirement for both ligand- and receptor-dependent occupancy of the VDRE for vitamin D responsive enhancement of osteocalcin gene transcription.
Breen
E C
EC
Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01655.
van Wijnen
A J
AJ
Lian
J B
JB
Stein
G S
GS
Stein
J L
JL
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002117:Calcitriol / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D015675:Osteocalcin / Q000235:genetics*; D012516:Osteosarcoma; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D018167:Receptors, Calcitriol / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D015675:Osteocalcin; D002117:Calcitriol