Transcriptional repression is epigenetically marked by H3K9 methylation during SV40 replication

Abstract

Background: We have recently shown that T-antigen binding to Site I results in the replication-dependent introduction of H3K9me1 into SV40 chromatin late in infection. Since H3K9me2 and H3K9me3 are also present late in infection, we determined whether their presence was also related to the status of ongoing transcription and replication. Transcription was either inhibited with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidizole (DRB) or stimulated with sodium butyrate and the effects on histone modifications early and late in infection determined. The role of DNA replication was determined by concomitant inhibition of replication with aphidicolin.

Nucleosome positioning in the regulatory region of SV40 chromatin correlates with the activation and repression of early and late transcription during infection

“…This mutant is characterized by a deletion of T-antigen binding Site I and as a consequence does not repress early transcription like the wild-type virus (DiMaio and Nathans, 1980, 1982). We have used this mutant virus extensively to characterize various aspects of chromatin structure with and without repression of early transcription (Balakrishnan and Milavetz, 2006; Kallestad et al, 2014, 2013; Kube and Milavetz, 1989, 1996; Milavetz et al, 2012). …”

“…Since early transcription can occur as early as 30 min post-infection in our system (Balakrishnan and Milavetz, 2006; Kallestad et al, 2014), we analyzed minichromosomes isolated at this time by NGS. A bedgraph of the results of an analysis of chromatin obtained at 30 min post-infection digested with micrococcal nuclease is shown in Fig.…”

“…Both the wild-type 776 and mutant cs1085 SV40 viruses were gifts from Dr. Daniel Nathans. The conditions utilized for cell culture have been described previously (Kallestad et al, 2014, 2013; Milavetz et al, 2012). …”

“…The procedures used for the preparation of minichromosomes have been described previously (Kallestad et al, 2014, 2013; Milavetz et al, 2012). Briefly, sub-confluent monolayers of cells were infected with 50 PFU per cell of SV40 virus prepared by low multiplicity of infection for 48 h at which time the nuclei were prepared.…”

Epigenetics in Schistosomes: What We Know and What We Need Know

“…Histone methylation has been shown to play a role in both transcriptional activation and repression (Wang et al, 2001; Jeong et al, 2011; Kallestad et al, 2014; Figure 2B). Histone demethylation is mediated by two classes of demethylase: the Jumonji family and the flavin-dependent lysine-specific demethylase1 (KDM1/LSD1) and 2 (KDM2/LSD2) (Pedersen and Helin, 2010).…”