A splice variant of E2-2 basic helix-loop-helix protein represses the brain-specific fibroblast growth factor 1 promoter through the binding to an imperfect E-box.

摘要: We previously demonstrated that acis-element (−489 to −467) in the brain-specific fibroblast growth factor (FGF)-1 promoter (FGF-1.B) binds multiple nuclear factors, and this binding enhances transcriptional activity of promoter. Here we report isolation three cDNA clones, VL1, VL2 VL3, from a human brain stem expression library using four tandem repeats 26-base pair sequence (−492 as probe. These clones represent variant bHLH protein E2–2/SEF2–1 having 12 additional nucleotides encoding amino acids RSRS. The glutathione S-transferase (GST) fusion proteins VLl, VL2, VL3 immunologically react with anti-E2–2 antibody anti-GST-VL2 antibody. Electrophoretic mobility shift assay methylation interference revealed GST specifically bind an imperfect E-box (GACCTG) present sequence. Transient full-length E2–2 without RSRS U1240MG glioblastoma cells resulted repression FGF-1.B activity. further showed significant (>40 fold) by (lacking acid RSRS) when E47 reporter construct, containing hexameric site, was used. In contrast, has no effect on either FGF-1 or results suggest relative abundance two splice variants could be important determinant for FGF-1.