Glucocorticoid regulation of human BMP-6 transcription

Addition of dexamethasone (Dex) to human mesenchymal stem cells (hMSCs) resulted in a 16-fold increase in human bone morphogenetic protein-6 (hBMP-6) mRNA levels 24 h after treatment. Evaluation of luciferase expression after transfection of HeLa cells with hBMP-6 promoter/luciferase reporter constructs indicated that the hBMP-6 promoter activity was contained in a 268-bp region (-1051 to -784 where +1 is the translation start site) over 600 bases 5' to that previously published. It further showed that the promoter activity is regulated by glucocorticoid treatment. Analysis of RNA from hMSCs and HeLa cells by primer extension, RNase protection, and 5' RACE further narrowed the location of the transcription start site to an 84-bp region (-940 to -857). To determine whether this start site was regulated in hMSCs, hBMP-6 mRNA levels in control and Dex-treated cells were quantitated by RT-PCR using one primer set in the translated region of the gene and one located just 3' of the 84-bp region. Both primer sets showed hBMP-6 mRNA levels approximately 16- to 22-fold higher in the Dex-treated cells, demonstrating that hBMP-6 transcription is being regulated by glucocorticoids in the pluripotent hMSCs at the upstream transcription start site.