Human Neurotropic Virus Research Articles

A nuclear protein derived from brain cells stimulates transcription of the human neurotropic virus promoter, JCVE, in vitro.

The 98-base pair enhancer/promoter sequence is critical for cell type-specific transcription of the human neurotropic viral promoter, JCVE, in glial cells. Transcriptionally active extracts were prepared from glial cells and used to identify cis- and trans-acting regulatory elements that are involved in the glial-specific activation of the JCVE promoter. Results indicate that multiple regulatory sequences within the 98-base pair repeat specifically bind to nuclear proteins present in glial cells and positively regulate viral early RNA synthesis. The central region of the repeat, designated domain-B, interacts with a 45-kDa nuclear protein present in brain cells. This brain-specific protein was purified by conventional and DNA affinity chromatography. Complementation of the highly purified protein with HeLa extract significantly increased JCVE promoter activity. Thus, association of the novel glial-origin transcription factor with its target sequence increases transcription of the JCVE promoter in a non-glial context.

Regulation of a human neurotropic virus promoter, JCVE: identification of a novel activator domain located upstream from the 98 bp enhancer promoter region

Transcription of the human neurotropic virus promoter, JCVE, and its regulation in glial cells are controlled by the 98 bp tandem repeats positioned between the viral early and late genes. Here, we show that a region, designated domain-D, located upstream from the 98 bp repeats functions as a transcriptional activator and increases JCVE promoter activity. Using the reporter SV40E promoter fused to the bacterial chloramphenicol acetyltransferase (CAT) gene, we demonstrate that domain-D stimulates the basal SV40E promoter activity in glial and to a lesser degree in HeLa cells. Results from gel mobility-shift assays indicate that domain-D interacts with proteins derived from glial and HeLa extracts and results in the formation of specific DNA-protein complexes. Through UV cross-linking assays, we demonstrate that these complexes have similar electrophoretic mobilities which comigrate with the 43-50 Kd proteins derived from glial and HeLa cells. These findings, together with our previous observations, imply that the JCVE control region is composed of multiple common and specific activator domains that may account for the increased expression of the promoter in glial cells. The possible role of the D-binding protein in transcription of the JCVE promoter is discussed.