Dynamic organization of splicing factors in adenovirus-infected cells

Abstract

Adenovirus infection affects the nuclear distribution of host splicing factors. Late phase-infected cells contain discrete clusters of small nuclear ribonucleoproteins (snRNPs) that are separate from centers containing the viral 72-kilodalton DNA-binding protein (72K protein). In the present study, we demonstrate that these snRNP clusters also contain splicing factors from the SR protein family. We show that a previously described monoclonal antibody, 3C5, detects SR proteins. Furthermore, we demonstrate that late region 3 transcription occurs at a maximal rate in infected cultures in which greater than 90% of the cells contain the snRNP clusters, indicating that such cells are actively transcribing their late genes. During the onset of the late phase, the intranuclear distribution of splicing factors is very different from that seen after the late phase is established. When late viral transcription commences, cells with snRNP clusters are less prevalent than in cultures that are maintaining maximum levels of late transcription. Instead, a cell type which shows snRNPs, concentrated in foci that also contain the viral 72K DNA-binding protein is detected. This cell type disappears from cultures by 18 to 20 h after a high-multiplicity infection. These results suggest a dynamic organization of splicing factors in infected cells that can be correlated to the status of viral gene expression. Our work also provides an explanation for the differing results that have been published concerning the organization of splicing factors in the adenovirus-infected cell nucleus (L. F. Jiménez-García and D. L. Spector, Cell 73:47-59, 1993). During the present study we observed that a monoclonal antibody against the SC-35 protein, which was used by Jiménez-García and Spector to study the localization of the SC-35 splicing factor in adenovirusinfected cells, cross-reacts with the adenovirus 72K DNA-binding protein and is thus unsuitable for this type of study.

Morphological, Biochemical, and Functional Study of Viral Replication Compartments Isolated from Adenovirus-Infected Cells

“…The RNA-Seq analysis of viral late mRNA in RCf indicates that the production of the different species of fiber mRNA is established at adenovirus RC. These findings are in agreement with previous reports that have shown both introns and exons from the MLTU are present in PRZ and in IG, suggesting that splicing occurs in both compartments (31,32,37,38,41,42,74,77,78,88,102,113). However, the data presented here suggest either that IG are coisolated in the RCf or that all IG components required for complete splicing of viral late mRNA are coopted to adenovirus RC ( Fig.…”

“…Like other DNA viruses that replicate in the nucleus, upon infection of the cell, adenovirus (Ad) DNA is delivered into the cell nucleus, where it localizes to PML NB by an uncharacterized mechanism (27). Components of the PML NB, together with those of nucleoli, Cajal bodies, IG, and other nuclear domains that regulate RNA biogenesis, are recruited to RC, where the adenoviral genome is replicated and expressed (27)(28)(29)(30)(31)(32). Components of the DNA repair machinery, signal transduction factors, tumor suppressor proteins, and innate immune response proteins also are recruited to these sites (22)(23)(24)(33)(34)(35)(36).…”

Functional inactivation of the SR family of splicing factors during a vaccinia virus infection

“…Quantitative data of splicing efficiencies derived from three independent experiments are shown at the bottom. scientific report enlarged nuclear speckles (data not shown), as has been observed in late adenovirus-infected cells (Bridge et al, 1995). It is also possible that VH1 does not function as a IIIa splicing enhancer regulator because it de-phosphorylates additional splicing factors required for spliceosome assembly and/or splicing in HeLa-NE.…”

Dilated cardiomyopathy caused by tissue-specific ablation of SC35 in the heart

“…Strikingly, SR protein function and regulation have been shown to be cellular targets for three different viruses. Adenoviral infection was found to induce massive reorganization of the cellular splicing machinery (Jimenez-Garcia and Spector, 1993;Bridge et al, 1995). It was later shown that the virus E4-ORF4 protein interacts with the cellular phosphatase 2A as well as a subset of SR proteins, thereby inducing SR protein dephosphorylation (Kanopka et al, 1998;Estmer Nilsson et al, 2001).…”