Nuclear Organization of Gene Expression in Adenovirus Infected Cells

Sammanfattning: Adenovirus infected cells provide a good model system for studying nuclear organization during RNA production and transport. This thesis is focused on the dynamic organization of splicing factors during the late phase of Adenovirus infection in HeLa cells, the nuclear localization of viral RNA, and the pathway used for viral RNA transport to the cytoplasm.Splicing factors are relocalized from interchromatin granule clusters to sites of transcription in Adenovirus infected cells at intermediate times of infection. Later, splicing factors and viral RNA accumulate posttranscriptionally in interchromatin granule clusters. The release of the splicing factors from transcription sites was energy dependent or preceded by energy requiring mechanisms. Our data indicated that phosphorylation events inhibited by staurosporine, and 3' cleavage of the transcript are two possible mechanisms involved prior to the release of the RNP complex from transcription sites.A viral protein derived from orf6 of early region 4, 34K, is important for the nuclear stability and transport of late viral mRNA derived from the major late transcription unit. A viral mutant lacking this region is defective for posttranscriptional accumulation of viral mRNA in interchromatin granule clusters, and for the accumulation of viral RNA in the cytoplasm. These results suggest that posttranscriptional accumulation of viral RNA in interchromatin granule clusters may contribute to the maturation of the RNP complex or sorting of RNAs and proteins, to prepare the final RNP complex for transport to the cytoplasm.A previous model suggested that adenoviral late mRNA is transported to the cytoplasm by utilizing the CRM-1 pathway. This pathway can be blocked by the drug leptomycin B. The data presented in paper IV suggests that this model might not be applicable, since leptomycin B did not inhibit adenoviral late gene expression.