INSIGHTS INTO VZV TRANSCRIPTIONAL CONTROL: THE USF-BINDING PROMOTER ELEMENT IN VZV GENE 4 IS REQUIRED FOR EFFICIENT ACTIVITY IN THE CONTEXT OF THE GENOME

*Paul R. Kinchington(1,2), Karen Fite(1), Eric Michael(3) & Marvin Sommer(2)
(1) Departments of Ophthalmology, (2)Molecular Genetics and Biochemistry,
(3) Department of Anesthesiology & Critical Care, University of Pittsburgh, Pittsburgh PA and (4) Department of Pediatric Infectious Diseases, University of Stanford, Stanford, CA

To gain insight into how VZV genes are regulated, we have examined the promoter driving expression of VZV gene 4, which encodes an immediate early gene that gives rise to a regulatory protein with post transcriptional activities. Using transient transfection-VZV superinfection studies, we previously identified a cis element in the gene 4 promoter which, when altered, compromised promoter activation by VZV co-infection. The element bound the cellular transcription cofactors USF and AP-1. We now show that the cis element plays a role in the efficient activation of the gene 4 promoter in the context of the VZV genome. Using cosmids, infectious recombinant VZV were
derived that contained, in either orientation, a hybrid gene 4 promoter-CAT gene and one in which the USF element was altered by mutagenesis. CAT assays from parallel infections using equivalent infectious virus indicated that CAT expression from the mutated gene 4 promoter was 18-32% of the activity of the wild-type promoter. These data validate a role for USF in obtaining efficient expression of gene 4. As USF-like elements are present upstream of at least 12 additional VZV genes, these results strongly suggest a role for the cellular USF transcription factors in VZV gene expression.

Corresponding Author: Paul R. Kinchington, Ph.D. Associate Professor, Departments of Ophthalmology, Molecular Genetics and Biochemistry, University of Pittsburgh, 203 Lothrop Street, Pittsburgh PA 15213, USA