Replication-Uncoupled Histone Deposition during Adenovirus DNA Replication

Department of Infection Biology, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
Journal of Virology (Impact Factor: 4.65). 04/2012; 86(12):6701-11. DOI: 10.1128/JVI.00380-12
Source: PubMed

ABSTRACT In infected cells, the chromatin structure of the adenovirus genome DNA plays critical roles in its genome functions. Previously, we reported that in early phases of infection, incoming viral DNA is associated with both viral core protein VII and cellular histones. Here we show that in late phases of infection, newly synthesized viral DNA is also associated with histones. We also found that the knockdown of CAF-1, a histone chaperone that functions in the replication-coupled deposition of histones, does not affect the level of histone H3 bound on viral chromatin, although CAF-1 is accumulated at viral DNA replication foci together with PCNA. Chromatin immunoprecipitation assays using epitope-tagged histone H3 demonstrated that histone variant H3.3, which is deposited onto the cellular genome in a replication-independent manner, is selectively associated with both incoming and newly synthesized viral DNAs. Microscopic analyses indicated that histones but not USF1, a transcription factor that regulates viral late gene expression, are excluded from viral DNA replication foci and that this is achieved by the oligomerization of the DNA binding protein (DBP). Taken together, these results suggest that histone deposition onto newly synthesized viral DNA is most likely uncoupled with viral DNA replication, and a possible role of DBP oligomerization in this replication-uncoupled histone deposition is discussed.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: DNA tumor viruses including members of the polyomavirus, adenovirus, papillomavirus, and herpes virus families are presently the subject of intense interest with respect to the role that epigenetics plays in control of the virus life cycle and the transformation of a normal cell to a cancer cell. To date, these studies have primarily focused on the role of histone modification, nucleosome location, and DNA methylation in regulating the biological consequences of infection. Using a wide variety of strategies and techniques ranging from simple ChIP to ChIP-chip and ChIP-seq to identify histone modifications, nuclease digestion to genome wide next generation sequencing to identify nucleosome location, and bisulfite treatment to MeDIP to identify DNA methylation sites, the epigenetic regulation of these viruses is slowly becoming better understood. While the viruses may differ in significant ways from each other and cellular chromatin, the role of epigenetics appears to be relatively similar. Within the viral genome nucleosomes are organized for the expression of appropriate genes with relevant histone modifications particularly histone acetylation. DNA methylation occurs as part of the typical gene silencing during latent infection by herpesviruses. In the simple tumor viruses like the polyomaviruses, adenoviruses, and papillomaviruses, transformation of the cell occurs via integration of the virus genome such that the virus's normal regulation is disrupted. This results in the unregulated expression of critical viral genes capable of redirecting cellular gene expression. The redirected cellular expression is a consequence of either indirect epigenetic regulation where cellular signaling or transcriptional dysregulation occurs or direct epigenetic regulation where epigenetic cofactors such as histone deacetylases are targeted. In the more complex herpersviruses transformation is a consequence of the expression of the viral latency proteins and RNAs which again can have either a direct or indirect effect on epigenetic regulation of cellular expression. Nevertheless, many questions still remain with respect to the specific mechanisms underlying epigenetic regulation of the viruses and transformation.
    Methods in molecular biology (Clifton, N.J.) 01/2015; 1238:569-96. DOI:10.1007/978-1-4939-1804-1_30 · 1.29 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: During infection by human adenovirus (HAdV), the proteins encoded by the early region 1A (E1A) gene bind and appropriate components of the cellular transcriptional machinery to activate viral early genes transcription. Previously, we identified roles for the hBre1 and the hPaf1 complexes in E1A mediated transcriptional activation of HAdV early genes. Here we show that E1A binds hBre1 directly and that this complex targets the hPaf1 complex via the Rtf1 subunit. Depletion of hPaf1 reduces E1A dependent activation of transcription from the E2e, E3 and E4 viral transcription units, and this does not result from a reduced ability of RNA polymerase II to be recruited to the promoter proximal regions of these genes. In contrast, depletion of hPaf1 reduces the occupancy of RNA polymerase II across these transcription units. This is accompanied by a reduction in H3K36 trimethylation, a histone post-translational modification associated with efficient transcriptional elongation, and a reduction in full length transcripts from these genes. Together, these results indicate that E1A uses hBre1 to recruit the hPaf1 complex in order to optimally activate viral early transcription by enhancing transcriptional elongation. This work provides the mechanism by which the hPaf1 complex contributes to E1A dependent activation of early gene transcription. The work also demonstrates that E1A induces gene expression by stimulating transcriptional elongation in addition to its better characterized effects on transcriptional initiation.
    Journal of Virology 03/2014; 88(10). DOI:10.1128/JVI.03518-13 · 4.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Adenovirus (Ad) vectors are currently the most commonly used platform for therapeutic gene delivery in human gene therapy clinical trials. Although these vectors are effective, many researchers seek to further improve the safety and efficacy of Ad-based vectors through detailed characterization of basic Ad biology relevant to its function as a vector system. Most Ad vectors are deleted of key, or all, viral protein coding sequences, which functions to not only prevent virus replication but also increase the cloning capacity of the vector for foreign DNA. However, radical modifications to the genome size significantly decreases virion stability, suggesting that the virus genome plays a role in maintaining the physical stability of the Ad virion. Indeed, a similar relationship between genome size and virion stability has been noted for many viruses. This review discusses the impact of the genome size on Ad virion stability and emphasizes the need to consider this aspect of virus biology in Ad-based vector design.
    Viruses 09/2014; 6(9):3563-3583. DOI:10.3390/v6093563 · 3.28 Impact Factor


Available from