Identification of a novel nuclear factorâkappaB sequence involved in expression of urokinaseâtype plasminogen activator receptor
2000
Wang, Yao | Dang, Jinjun | Wang, Heng | Allgayer, Heike | Murrell, George A. C. | Boyd, Douglas
We have previously defined the promoter of human urokinaseâtype plasminogen activator receptor (uPAR) gene in a 188âbp fragment between bases −141 and +47 relative to the translation start site. Here, we report that a novel nuclear factorâkappaB (NFâκB)âlike sequence (5′âGGGAGGAGTCâ3′) at −45 is located in the uPAR promoter and one of the two DNaseâIâprotected regions, region I between bases −51 and −30. This NFâκBâlike motif differs at positions 7–9 from the decameric consensus sequences of NFâκB (5′âGGGRNNYYCCâ3′ where R indicates A or G, Y indicates C or T, and N indicates any nucleotide) and at positions 1 and 7–9 from the κBâlike motifs (5′âHGGARNYYCCâ3′ where H indicates A, C, or T, R indicates A or G, Y indicates C or T, and N indicates any nucleotide). Nuclear extracts from HCT116 cells contain proteins that specifically bind to the NFâκBâlike site at position −45. Mutation of the NFâκBâlike motif decreased the binding of transcription factor NFâκB and reduced the uPAR promoter activity in comparison with the wildâtype sequences. Coâtransfection with a dominant negative IâκB kinaseâ2 expression vector reduced uPAR promoter activity by 65–75%. These results demonstrate that a previously uncharacterized NFâκB motif is required for uPAR promoter activity.
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