To clone and identify the proteins involved in regulating the transcription of hTERT and study the role of genes in both hTERT transcription and telomerase activity. Methods The full cDNA of COUP-TFII was cloned from HeLa cDNA library by hTERT promoter-based yeast one-hybrid assay and then in-frame inserted into His-tag fusion expression vector pEK318. The His-tag COUP-TFII fusion proteins were purified by Ni-NTA chromatography. The interaction of COUP-TFII with hTERT promoter in vitro was identified by electrophoretic mobility shift assay and Footprint. The role of COUP-TFII in both hTERT transcription and telomerase activity were probed through Luciferase reporter assay

Northern blot

and TRAP-PCR ELISA. Results COUP-TFII could firmly bind to the downstream E-box and the other two binding sites in hTERT promoter. Luciferase reporter assay indicated COUP-TFII could suppress hTERT promoter activity and stable introduction of COUP-TFII into HeLa cells also decreased both endogenous hTERT transcription and telomerase activity. Conclusion The human COUP-TFII can firmly bind to hTERT promoter

and inhibit telomerase activity through decreasing hTERT transcription. It will greatly facilitate understanding of telomerase regulation in normal and cancer cells