Adenovirus replication is coupled with the dynamic properties of the PML nuclear structure.

Abstract

Wild-type PML and at least four other novel proteins are localized within discrete nuclear structures known as PODs. We demonstrate here that during adenovirus infection, immediate early viral proteins from the E1 and E4 transcription units associate with the POD, which in turn undergoes a dramatic morphological change. During this process, the auto-antigen Sp-100 and NDP55 but not PML, relocate from the POD to the viral inclusion bodies, the sites of adenovirus DNA replication and late RNA transcription. The E4-ORF3 11-kD protein alone will induce this reorganization and reciprocally, viruses carrying mutations in the E4-domain fail to do so. These same viral mutants are defective in viral replication as well as the accumulation of late viral mRNAs and host cell transcription shutoff. We show that interferon (INF) treatment enhances the expression of PML, reduces or blocks PODs reorganization, and inhibits BrdU incorporation into viral inclusion bodies. In addition, cell lines engineered to overexpress PML prevent PODs from viral-induced reorganization and block or severely delay adenovirns replication. These results suggest that viral replication relies on components of the POD and that the structure is a target of early viral proteins.

SUMO modification of E1B-55K oncoprotein regulates isoform-specific binding to the tumour suppressor protein PML

“…Representative results of IF analysis is shown in Figure 4A. As expected, PML is relocalized in virus-infected cells (Figures 4Ab, Ae, Ah, and Ak) by E4orf3 in so-called track-like structures (Carvalho et al, 1995;PuvionDutilleul et al, 1995;Doucas et al, 1996), whereas E1B-55K shows a more complex localization pattern (Ornelles and Shenk, 1991). However, a subpopulation of about 30% of infected HepaRG cells exhibit small nuclear accumulations of the viral protein (Figure 4Aa).…”

“…These results furthermore highlight that E1B-55K function synergistically involves proper localization, functional protein interaction domains and posttranslational modification as the intrinsic PML-binding capability in total cell lysates per se is not enough to achieve a specific subcellular localization (Figures 1 and 4). This hypothesis in summary might also explain the involvement of SUMOylation in nuclear localization of E1B-55K, the relocalization of E1B-55K on expression of E4orf6 and the transient colocalization of E1B-55K with PML during very early stages of infection (Younghusband, 1985;Ornelles and Shenk, 1991;Carvalho et al, 1995;Doucas et al, 1996;Ko¨nig et al, 1999;Lethbridge et al, 2003;Endter et al, 2005). The observation that multiple cellular pathways are extensively regulated by posttranslational modification through different SUMO isoforms despite only low amounts of detectable modified effector proteins currently represents one of the most inapprehensible questions perceptively termed the SUMO enigma (Hay, 2005).…”

“…Over the last years, it has become evident that cellular PML bodies facilitate various functions in cell metabolism including cell differentiation (Salomoni, 2009) (Carvalho et al, 1995;Puvion-Dutilleul et al, 1995;Doucas et al, 1996). Furthermore, PML bodies are proposed to mediate a general intracellular barrier for viral infections (Everett, 2001;Everett and ChelbiAlix, 2007;Tavalai and Stamminger, 2008).…”

“…Viral infection alters the affinity of E1B-55K for specific PML isoforms Previously published data illustrate that the adenoviral protein E4orf3 is necessary and sufficient to disrupt cellular PML bodies during adenoviral infection (Carvalho et al, 1995;Puvion-Dutilleul et al, 1995;Doucas et al, 1996). As the E4orf3-mediated PML relocalization seems to be conserved among human adenoviruses (Stracker et al, 2005), it has been proposed that this might be a general mechanism to counteract the antiviral capabilities of PML bodies (Ullman et al, 2007;Ullman and Hearing, 2008).…”

The adenovirus type 5 E1B-55K oncoprotein is a highly active shuttle protein and shuttling is independent of E4orf6, p53 and Mdm2

“…Although, it was proposed that a complex of E4orf6 and E1B-55K mediates viral RNA transport in which E4orf6 confers nuclear import and export (Dobbelstein et al, 1997), the detailed mechanism by which these adenovirus proteins promote nucleo-cytoplasmic RNA transport is not completely understood. Recent studies indicate that E4orf6, and in particular E4orf3, initiate the nuclear reorganization of cellular and viral factors that might also indirectly favour this process (Carvalho et al, 1995;Doucas et al, 1996). At late times of infection E1B-55K and E4orf6 are localized within and at the periphery of nuclear viral inclusions, believed to be the sites of viral transcription and/or replication (Ornelles and Shenk, 1991).…”