THE TRANSCRIPTIONAL ENHANCER ELEMENT, KAPPA-B, REGULATES PROMOTER ACTIVITY OF THE HUMAN NEUROTROPIC VIRUS, JCV, IN CELLS DERIVED FROM THE CNS

Studies on the regulation of the human neurotropic virus (JCV) promoter, have been focused primarily on the 98 bp tandem repeat sequence which confers glial-specificity to viral gene expression. We demonstrate that a distinct regulatory element outside of the 98 bp region, which spans a stretch of 10 nucleotides (nt) (5'-GGGAATTTCC-3') increases transcriptional activity of JCV late (JCV(L)) and early (JCV(E)) promoters in glial cells. Sequence analysis of this motif reveals extensive homology to the kappaB sequence of HIV-1 (5'-GGGACTTTCC-3'). A DNA fragment corresponding to the 10 nt sequence of JCV exhibits transcriptional activity when placed upstream of the test promoter in glial cells. The induction mediated by this regulatory motif is moderately enhanced in response to phorbol 12-myristate 13-acetate (PMA) in glial cells. Band-shift and UV-crosslinking experiments suggest that glial cells constitutively produce proteins that specifically interact with the JCV kappaB, but not the HIV-1 kappaB motif. Treatment of cells with PMA results in formation of new complexes that are sensitive to the kappaB sequences derived from the JCV and HIV-1 genomes. These results suggest that the kappaB sequence located in the JCV genome may play a role in transcriptional regulation of JCV gene expression by interacting with inducible and uninducible nuclear proteins from glial cells.