Enhancer of human polyoma JC virus contains nuclear factor I-binding sequences; analysis using mouse brain nuclear extracts.

Neurotrophic human JC virus carries a 98 bp duplicate enhancer responsible for tissue-specific gene expression. DNase I footprinting studies using mouse brain nuclear extracts revealed weak (pseudo NFI motif) and strong (NFI motif) nuclear factor I-binding sequences just upstream (at 229) and in the middle (at 156 and 58) of the enhancer, respectively. In vitro transcription driven in brain extracts demonstrated that the NFI motif is a possible transcription control element. Together with previous observations (Khalili, K., Rappaport, J. and Khoury, G. (1988) EMBO J. 7, 1205-1210 (20], the NFI motif is suggested to play an important role in early gene expression of JCV.