Promoter-Targeted Histone Acetylation of Chromatinized Parvoviral Genome Is Essential for the Progress of Infection

Abstract

The association of host histones with parvoviral DNA is poorly understood. We analyzed the chromatinization and histone acetylation of canine parvovirus DNA during infection by confocal imaging and in situ proximity ligation assay combined with chromatin immunoprecipitation and high-throughput sequencing. We found that during late infection, parvovirus replication bodies were rich in histones bearing modifications characteristic of transcriptionally active chromatin, i.e., histone H3 lysine 27 acetylation (H3K27ac). H3K27ac, in particular, was located in close proximity to the viral DNA-binding protein NS1. Importantly, our results show for the first time that in the chromatinized parvoviral genome, the two viral promoters in particular were rich in H3K27ac. Histone acetyltransferase (HAT) inhibitors efficiently interfered with the expression of viral proteins and infection progress. Altogether, our data suggest that the acetylation of histones on parvoviral DNA is essential for viral gene expression and the completion of the viral life cycle. IMPORTANCEViral DNA introduced into cell nuclei is exposed to cellular responses to foreign DNA, including chromatinization and epigenetic silencing, both of which determine the outcome of infection. How the incoming parvovirus resists cellular epigenetic downregulation of its genes is not understood. Here, the critical role of epigenetic modifications in the regulation of parvovirus infection was demonstrated. We showed for the first time that a successful parvovirus infection is characterized by the deposition of nucleosomes with active histone acetylation on the viral promoter areas. The results provide new insights into the regulation of parvoviral gene expression, which is an important aspect of the development of parvovirus-based virotherapy. N uclear chromatin is composed of DNA and histone proteins (1). The histone proteins assemble DNA into nucleosomes, the composition and spacing of which contribute to higher-order chromatin packing. The chromatin is organized into regions of less-condensed actively transcribed chromatin (euchromatin) and highly condensed transcriptionally repressed chromatin (heterochromatin). Epigenetic modifications of histone proteins have been shown to correlate with the spatial distribution of active and repressed chromatin (2, 3). The acetylation of lysine 9 or 27 of histone H3 (H3K9ac and H3K27ac, respectively) and trimethylation of lysine 4 (H3K4me3) correlate with transcriptional activity, while repressed chromatin is characterized by, e.g., trimethylation or dimethylation of the same H3 lysine residues (H3K9me3 and H3K27me3 as well as H3K9me2 and H3K27me2) (4-8).Foreign DNA introduced into mammalian cells can be recognized as a threat by the host cell. The cellular responses to the foreign DNA, such as viral DNA, include the chromatinization of the entering DNA, leading to its transcriptional silencing (9-11). How viruses resist cellular chromatinization and silencing is known for only a few viruses (9, 12, 13). These include h...

Molecular Characterization and Evolutionary Analyses of Carnivore Protoparvovirus 1 NS1 Gene

“…There are also limited studies on the NS1 protein, based only on evaluations of its functions [66,67,68] and on the potential location of its functional domains [10,22,23]. Changes in specific residues of NS1 CPV sequence [27] or affecting functional domains in others Carnivore protoparvovirus 1 such as mink enteritis parvovirus [69] were hypothesized as potentially affecting the functions of this protein.…”

The Involvement of Histone H3 Acetylation in Bovine Herpesvirus 1 Replication in MDBK Cells

“…During HSV-1 productive infection, the viral genomes are associated with histones immediately after injection into the nucleus, and viral proteins ICP0 and VP16 are required to enhance histone acetylation on the viral genome to enable efficient viral gene expression [ 18 , 40 ]. During canine parvovirus infection, cellular histones are associated with viral DNA, and histone acetylation on parvoviral DNA is essential for viral gene expression [ 20 ]. BoHV-1 tegument protein VP22 associates with histones and thereby decreased histone H4 acetylation in infected cells or VP22 transfected cells [ 22 ].…”

“…For example, during HSV-1 productive infection histone H3 associates with viral DNA at the IE(immediate early) promoters, thereby recruiting the chromatin remodeling factors into viral replication compartments [ 16 , 17 , 18 , 19 ], which facilitates viral gene expression and DNA replication. The acetylation of histones on parvoviral DNA is essential for viral gene expression and completion of the viral life cycle [ 20 ]. Histone acetylation is essential for influenza A virus infection, since the inhibition of histone acetylation by histone acetyltransferase (HAT) inhibitors can attenuate its infection [ 21 ].…”

Polycomb Repressive Complex 2 Enacts Wnt Signaling in Intestinal Homeostasis and Contributes to the Instigation of Stemness in Diseases Entailing Epithelial Hyperplasia or Neoplasia

“…Analyses were performed essentially as described in (see Supporting Information materials and methods for detailed descriptions of data analyses)…”