Abstract
Fibroblast growth factor 1 (FGF1) is one of the 22 members in the fibroblast growth factor family. FGF1 plays an important role in many biological processes such as cell differentiation, wound healing, and tissue growth. The FGF1 gene spans over 120 kilobase pairs and encodes four different transcripts, namely FGF-1.A, -1.B, -1.C, -1.D, which were driven by four different tissue specific promoters, respectively. It has been reported that FGF-1.B is the major transcript expressed in brain. Two positively regulatory elements, RR1 and RR2, were identified to be crucial for the promoter activity. Further evidences suggested that the DNA-protein interaction in RR2 region requires at least the 18-bp sequence located between positions -484 to -467. However, the transcription factors bound on the 18-bp have not been identified. Here, using the bioinformatics tools, we found an 18-base pair binding candidate, RFX1. Using chromatin immunoprecipitation assay (ChIP) and electrophoretic mobility shift assay (EMSA), we confirmed that RFX1 bound the 18-base pair in vivo and in vitro. When transiently overexpressing the RFX1 in U-1240 MG glioblastoma cells, we found that RFX1 elevated FGF-1.B promoter activity in a dose dependent manner. In addition, knocking down of RFX1 by RNA interference negatively regulated the promoter activity. These results demonstrated that RFX1 plays an important role in the transcription regulation of FGF-1.B.