Regulation of gene expression occurs at the level of transcription, processing, transport, and mRNA translation. The primary goal of this section is to investigate the transcriptional and translational control mechanisms responsible for regulated gene expression. To identify components required for transcription of genes by RNA polymerase II, stable intermediate complexes formed during assembly of specific transcription complexes are being purified and characterized using plasmids containing multiple repeats of the Adenovirus 2 major late promoter or specific promoter elements. These have been constructed to purify proteins which recognize and bind to specific DNA sequences which regulate gene activity. These constructs have been applied towards the purification of specific transcription factors, as well as the generation of cellular extracts specifically deficient in single transcription components, for functional studies. A mouse model of B-thalassemia resulting from deletion of the entire Beta-major globin gene has been studied to determine the mechanism of the compensatory increase in Beta-minor globin gene expression. Compensation occurs almost entirely at the translational level, rather than by increased transcription and/or processing of Beta-minor globin mRNA. Alteration of the activity of the initiation factor eIF-4F is strongly suggested. During infection by adenoviruses and influenza viruses, activation of host cell ds-RNA dependent eIF-2 Alpha kinase is prevented by VA1 RNA and an unknown, but functionally similar influenza gene product. The mechanisms by which certain cell lines escape viral takeover of their translational machinery is being investigated. To understand the regulation of translation factors which participate in virus-host interactions, the genes for subunits of eIF-2 and eIF-2B are being identified and sequenced.
