Regulation of brain-specific transcription of the mouse myelin basic protein gene: function of the NFI-binding site in the distal promoter.

We investigated brain-specific transcription elements in the distal region (-253 to -54) of the mouse myelin basic protein (MBP) promoter by in vitro transcription using mouse brain nuclear extracts. Using deletion and base substitution mutants, we identified one tissue-specific transcription element at the downstream core of the NFI-site between -115 and -111. Foot-printing assay demonstrated that three transcription factors bind around this element; NFI-related (-130 to -111), M1 (-110 to -97) and Sp1 (-92 to -84). NFI-related factor(s) in brain extracts consisted of a characteristic population which was different from that in other tissues. Methylation interference experiments revealed that this factor(s) interacted with the NFI-downstream core in a brain-specific manner. We suggest the existence of a brain-specific NFI-related factor(s).