Impact of Adenovirus E4-ORF3 Oligomerization and Protein Localization on Cellular Gene Expression

Abstract

The Adenovirus E4-ORF3 protein facilitates virus replication through the relocalization of cellular proteins into nuclear inclusions termed tracks. This sequestration event disrupts antiviral properties associated with target proteins. Relocalization of Mre11-Rad50-Nbs1 proteins prevents the DNA damage response from inhibiting Ad replication. Relocalization of PML and Daxx impedes the interferon-mediated antiviral response. Several E4-ORF3 targets regulate gene expression, linking E4-ORF3 to transcriptional control. Furthermore, E4-ORF3 was shown to promote the formation of heterochromatin, down-regulating p53-dependent gene expression. Here, we characterize how E4-ORF3 alters cellular gene expression. Using an inducible, E4-ORF3-expressing cell line, we performed microarray experiments to highlight cellular gene expression changes influenced by E4-ORF3 expression, identifying over four hundred target genes. Enrichment analysis of these genes suggests that E4-ORF3 influences factors involved in signal transduction and cellular defense, among others. The expression of mutant E4-ORF3 proteins revealed that nuclear track formation is necessary to induce these expression changes. Through the generation of knockdown cells, we demonstrate that the observed expression changes may be independent of Daxx and TRIM33 suggesting that an additional factor(s) may be responsible. The ability of E4-ORF3 to manipulate cellular gene expression through the sequestration of cellular proteins implicates a novel role for E4-ORF3 in transcriptional regulation.

Alterations of Nuclear Architecture and Epigenetic Signatures during African Swine Fever Virus Infection

“…Most probably, this close vicinity also occurs with γH2AX foci, although, because of its pan-nuclear distribution, this juxtaposition to PML-NBs could not be easily recognized in ASFV-infected cells (data not shown). The observed p-p53 and pATR accumulations corroborate the increased expression levels of ATR-related factors reported in ASFV infection [ 6 ], enhancing the proximity and functional crosstalk between activated DDR factors and PML-NBs thus interfering with the interferon-mediated antiviral responses, as described for other viral infections [ 40 , 42 , 43 ].…”

Transcriptome sequencing and development of an expression microarray platform for liver infection in adenovirus type 5-infected Syrian golden hamsters

“…A very recent study used microarray technology to examine cellular transcription in response to induction of the Ad2-coded E4orf3 protein in cells stably transfected with the gene for E4orf3 ( Vink et al, 2015 ). E4orf3 functions in Ad replication by causing cellular proteins to re-localize into filamentous nuclear inclusions termed “tracks”.…”

Adenovirus 5 E1A Interacts with E4orf3 To Regulate Viral Chromatin Organization

“…Cell and virus culture. IMR-90 (ATCC CCL-186), A549-E1A289R, U2OS-HA-E4orf3 (41), and HT1080 (ATCC CCL-121) cells were grown in Dulbecco's modified Eagle's medium (DMEM; HyClone) supplemented with 10% fetal bovine serum (Seradigm) and streptomycin and penicillin (HyClone). All virus infections were carried out in serum-free media for 1 h, after which saved complete medium was added without removal of the infection media.…”

“…Induction of HA-E4orf3 expression in U2OS-HA-E4orf3 cells was carried out by addition of 2 g/ml of doxycycline to the growth media for at least 16 h or as indicated in the figure legends. U2OS-HA-E4orf3 cells, when induced, express levels of E4orf3 similar to those of HAdV5-infected cells at 24 h after infection (41). A549-E1A289R cells were generated by transduction with a retrovirus expressing HAdV5 E1A289R and selection with G418.…”