The Sp1 and CBF/NF-Y transcription factors cooperatively regulate the mouse pro-alpha3(V) collagen gene (Col5a3) in osteoblastic cells.

The purpose of this study was to clarify the mechanism responsible for the transcriptional regulation of the mouse Col5a3 gene in osteoblastic cells. Transient transfection into rat osteosarcoma ROS17/2.8 cells demonstrated that a region from nucleotides 337 to 1 was involved in the transcriptional activity of the Col5a3 gene. An electrophoretic mobility shift assay showed that Sp1/Sp3 and CBF/NF-Y bound to a GC-rich domain (194/186) and a CCAAT box (134/130) in the Col5a3 gene, respectively. Introduction of mutations or deletion into a GC-rich domain, the CCAAT box, or both elements decreased the transcription activity. Overexpression of Sp1 increases the transcription activity and interferes with Sp family binding to the GC-rich domain to decrease promoter activity. Therefore, the transcription of the mouse Col5a3 gene is cooperatively regulated by Sp1 and CBF/NF-Y in osteoblastic cells.