The osteocalcin and collagen type I (alpha 1) promoters share common basal regulatory units.
Sequential activation of osteoblast-specific genes occurs during cell development. Regulation of these genes is through the cooperation between basal, hormone-responsive, and growth factor-responsive transcriptional control elements. The active hormone, 1,25-dihydroxyvitamin D3 plays an important role in the regulation of osteocalcin and other osteoblast-expressed genes. As well as containing a vitamin D response element, the upstream region of the osteocalcin promoter also has potent basal activity in the osteoblast-like ROS17/2.8 cell line. The present study identifies a short DNA sequence that contributes to basal promoter activity. This osteocalcin cis-acting response element (OSCARE-1) has two basal regulatory elements: a G/C-rich element and an adjacent reverse CCAAT element. Homologous sequences have been characterized as negative and positive basal regulatory elements, respectively, in the promoter of the collagen type I (alpha 1) gene. In electrophoretic mobility-shift assays, this collagen regulatory unit and OSCARE-1 produce similar banding patterns and bind common ROS17/2.8 nuclear proteins. Mutations of the G/C element in the collagen promoter showed that it functions as an inhibitory element in NIH-3T3 cells. Introduction of the same mutations into the G/C element of the OSCARE-1 unit exposed a similar repressive activity in NIH-3T3 cells, which correlated with an altered electrophoretic mobility-shift assay banding pattern. We have shown a similarity between a basal regulatory unit in the distal osteocalcin promoter and a unit in the proximal collagen type I (alpha 1) promoter. The fact that similar units are present in other osteoblast-specific promoters suggests that OSCARE-1-like units may be a common regulator of osteoblast-expressed genes.
Goldberg
D
D
Bone and Mineral Research Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, NSW, Australia.
Gardiner
E
E
Morrison
N
N
Eisman
J
J
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003094:Collagen / Q000235:genetics*; D000090602:Collagen Type I, alpha 1 Chain; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015675:Osteocalcin / Q000235:genetics*; D017354:Point Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
C000716127:COL1A1 protein, human; D000090602:Collagen Type I, alpha 1 Chain; D015675:Osteocalcin; D003094:Collagen