IDENTIFICATION OF A SEQUENCE-SPECIFIC SINGLE-STRANDED-DNA BINDING-PROTEIN THAT SUPPRESSES TRANSCRIPTION OF THE MOUSE MYELIN BASIC-PROTEIN GENE

The myelin basic protein (MBP) gene is expressed only in oligodendrocy tes and Schwann cells, and expression follows a tightly regulated deve lopmental time course. Cell type- and developmental stage-specific exp ression of the MBP gene appears to be regulated by a series of cis-act ing elements located upstream of the transcription start site. The pro ximal element of the MBP regulatory region (MB1), located between nucl eotides -14 and -50, is one of several elements participating in the p rogrammed expression of MBP. In this report, we describe the molecular cloning and characterization of myelin gene expression factor-2 (Myef -2), a protein isolated from mouse brain that binds specifically to si ngle-stranded DNA derived from the MB1 element and represses transcrip tion of the MBP gene in transient transfection assay. Myef-2 mRNA is d evelopmentally regulated in mouse brain; its peak expression occurs at postnatal day 7, prior to the onset of MBP expression, The developmen tal pattern of Myef-2 mRNA expression coincides with that previously d escribed for SCIP, a POU domain transcription factor that also repress es myelin basic protein expression. The myef-2 gene maps to mouse chro mosome 2. The relevance of these findings for regulation of MBP gene e xpression and oligodendrocyte differentiation is discussed.