Human JC Virus Nuclear Factor 1 Binding Motifs and Large Tumor Antigen Region Required for Transactivation of Late Promoter

Publisher Website
Google Scholar
Abstract
The nuclear factor 1 (NF‐1) motifs, NF‐1 II/III, in the two 98‐bp repeats of the transcription‐regulatory region of JC virus (JCV), have a critical role in brain‐specific transcription from the JCV early promoter‐enhancer. In this study, the role of these motifs in transactivation of the JCV late promoter‐enhancer (JCVL) was examined in differentiating glial P19 embryonal carcinoma cells. The expression of papovaviral large tumor antigen (T‐Ag) in the glial cells was shown by double immunofluorescence assays. By using site‐directed mutagenesis and in vivo assays, the two wild‐type NF‐1 II/III sites, but not the third site, were found to be essential for the transactivation of JCVL by JCV T‐Ag. In vitro transcription assays confirmed this specific transactivation and the transactivation was abolished by T‐Ag antibody. In electrophoretic mobility shift assays, expression of JCV T‐Ag increased the binding of a factor(s) to the 98‐bp repeat. T‐Ag antibody abolished the increase of binding. Binding assays with oligonucleotides of NF‐1 II/III motifs showed that the increased binding specifically required the wild‐type NF‐1 II/III sequences and confirmed the requirement of T‐Ag. To determine the region of T‐Ag necessary for transactivation of JCVL, the coding sequences were mutated. The amino‐terminal region of JCV Ag in amino acids 1–437 was essentially required for efficient transactivation. These results indicated that transactivation of JCVL and increased binding require a factor(s) found specifically in glial cells, the JCV NF‐1 II/III sites, and the T‐Ag amino‐terminal region.

This publication has 0 references indexed in Scilit: