Regulation of Transcription from the Human Muscle Phosphofructokinase P2 Promoter by the Sp1 Transcription Factor

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Abstract
The human muscle phosphofructokinase (HPFKM) p2 promoter contains sequence elements that are similar to the Sp1 transcription factor binding site consensus sequence. DNase I footprinting identified four regions of the HPFKM p2 promoter that bound purified Sp1. Gel retardation analysis using HeLa S3 nuclear extracts and purified Sp1 protein demonstrated that each of the four recognition elements bound the Sp1 transcription factor. The function of the HPFKM p2 promoter elements was examined in transient transfection assays using these binding sites cloned into a minimal promoter element. In Drosophila Schneider line-2 cells, each of these regulatory regions trans-activated transcription from a minimal promoter element in response to exogenously expressed Sp1. In addition, transcription from the HPFKM p2 promoter was shown to be trans-activated by exogenously expressed Sp1 in Drosophila Schneider line-2 cells. Deletion analysis of the HPFKM p2 promoter demonstrated that the promoter region between -66 and +16 was sufficient to confer sp1 responsiveness. This promoter region includes one of the regulatory elements footprinted by the purified Sp1 transcription factor and mediates the majority of the transcriptional activity from the HPFKM p2 promoter in the human cervical carcinoma cell line HeLa S3. This demonstrates that the HPFKM p2 promoter contains four functional Sp1 binding sites that may contribute to the level of transcription from this promoter in a variety of cell types.