Analysis of transcription control elements of the mouse myelin basic protein gene in HeLa cell extracts: demonstration of a strong NFI-binding motif in the upstream region.

Promoter elements of the mouse myelin basic protein (MBP) gene were analyzed by in vitro transcription using HeLa cell extracts. We demonstrated the MBTE (MBP transcription element), GC-box core and TATA-box elements, at -130, -93 and -34, respectively. The TATA-box was indispensable for the promoter function. The GC-box was suggested to function co-operatively with far upstream sequences including the MBTE. The MBTE was crucial to direct maximal transcription, and also functioned with a heterologous promoter irrespective of its orientation. We identified a ubiquitous binding factor which interacted specifically with the MBTE and activated transcription. Intensive foot-printing studies demonstrated that the MBTE had a NFI-binding sequence. The MBTE was considered to be one of the strongest NFI-binding motif among known cellular genes. Interestingly, similar strong NFI-binding motifs were suggested to be present in the enhancer of JC virus whose gene is expressed like the MBP gene, in the nervous system.