Molecular Cloning of the Human Platelet-Derived Growth Factor Receptor beta (PDGFR-beta) Promoter and Drug Targeting of the G-Quadruplex-Forming Region To Repress PDGFR-beta Expression

作者：Qin Yong; Fortin Jessica S; Tye Denise; Gleason Guzman Mary; Brooks Tracy A; Hurley Laurence H^*

来源：Biochemistry, 2010, 49(19): 4208-4219.

DOI：10.1021/bi100330w

To understand the mechanisms controlling platelet-derived growth factor receptor beta (PDGFR-beta) expression in malignancies, we have cloned and characterized the first functional promoter of the human PDGFR-beta gene, which has been confirmed by luciferase reporter gene assays. The transcription initiation sites were mapped by primer extension. Promoter deletion experiments demonstrate that the proximal, highly GC-rich region (positions -165 to -139) of the human PDGFR-beta promoter is crucial for basal promoter activity. This region is sensitive to SI nuclease and likely to assume a non-B-form DNA secondary structure within the supercoiled plasmid. The G-rich strand in this region contains a series of runs of three or more guanines that can form multiple different G-quadruplex structures, which have been subsequently assessed by circular dichroism. A Taq polymerase stop assay has shown that three different G-quadruplex-interactive drugs can each selectively stabilize different G-quadruplex structures of the human PDGFR-beta promoter. However, in transfection experiments, only telomestatin significantly reduced the human PDGFR-beta basal promoter activity relative to the control. Furthermore, the PDGFR-beta mRNA level in Daoy cells was significantly decreased after treatment with 1 mu M telomestatin for 24 h. Therefore, we propose that ligand-mediated stabilization of specific G-quadruplex structures in the human PDGFR-beta promoter can modulate its transcription.

• 出版日期2010-5-18