Analysis of cis-acting sequences from the myelin oligodendrocyte glycoprotein promoter

Myelin oligodendrocyte glycoprotein (MOG), a minor component of the myelin sheath, appears to be implicated in the late events of CNS myelinogenesis. To investigate the transcriptional regulation of MOG, 657 bp of the 5'-flanking sequence of the murine MOG gene, previously shown to induce the highest level of transcription in an oligodendroglial cell line, was analyzed by in vitro footprinting and electrophoretic mobility shift assays. This region contains at least three sites that contact nuclear proteins in vitro. Each region described in this study binds specific nuclear proteins and enhances transcription in the OLN-93 glial cell line. More specifically, a region located at position -93 to -73 bp, which displays 100% homology in mouse and human MOG promoters, presents distinct binding affinities between brain and liver nuclear proteins. The results obtained by supershift assay and site-directed mutagenesis reveal that this region contains an essential positive element (TGACGTGG) related to the cyclic AMP-responsive element CREB-1 and are additional evidence for the involvement of the cyclic AMP transduction pathway in oligodendrocyte development.