Identification of a novel silencer that regulates the myelin basic proteingene in neural cells

The myelin basic protein gene produces two families of proteins, the golli proteins and the 'classic' myelin basic proteins from three transcription s tart sites (tsp). The golli proteins are expressed from the first tsp, and little is known about genetic elements that control its activity. We have e xamined elements that may regulate the expression of the golli products pro duced from this promoter in neural cell lines with constructs containing up stream portions of the first tsp by transient transfection assays. Three pu tative regulatory elements were identified, among them a 345 bp novel silen cer region, termed the golli silencer region (GSR), which was characterized in detail. This silencer was responsible for a significant (approx. 60%) i nhibition of luciferase expression in PC12 cells. It was orientation-depend ent and a double dose of this GSR completely abolished expression of the lu ciferase reporter activity. Transfections with deleted constructs identifie d three critical sites that bind at least two repressor proteins. We postul ate that the silencer activity is the result of synergistic interactions be tween these repressor proteins and might involve the formation of a high-or dered protein-DNA structure. (C) 2000 Elsevier Science B.V. All rights rese rved.