Original Research ARTICLE
Transcription and replication result in distinct epigenetic marks following repression of early gene expression
- 1Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
- 2Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
Simian virus 40 (SV40) early transcription is repressed when the product of early transcription, T-antigen, binds to its cognate regulatory sequence, Site I, in the promoter of the SV40 minichromosome. Because SV40 minichromosomes undergo replication and transcription potentially repression could occur during active transcription or during DNA replication. Since repression is frequently epigenetically marked by the introduction of specific forms of methylated histone H3, we characterized the methylation of H3 tails during transcription and replication in wild-type SV40 minichromosomes and mutant minichromosomes which did not repress T-antigen expression. While repressed minichromosomes following replication were clearly marked with H3K9me1 and H3K4me1, minichromosomes repressed during early transcription were not similarly marked. Instead repression of early transcription was marked by a significant reduction in the level of H3K9me2. The replication dependent introduction of H3K9me1 and H3K4me1 into wild-type SV40 minichromosomes was also observed when replication was inhibited with aphidicolin. The results indicate that the histone modifications associated with repression can differ significantly depending upon whether the chromatin being repressed is undergoing transcription or replication.
Keywords: simian virus 40, viral epigenetics, H3K9, H3K4, transcription, replication
Citation: Kallestad L, Woods E, Christensen K, Gefroh A, Balakrishnan L and Milavetz B (2013) Transcription and replication result in distinct epigenetic marks following repression of early gene expression. Front. Genet. 4:140. doi: 10.3389/fgene.2013.00140
Received: 30 April 2013; Paper pending published: 22 May 2013;
Accepted: 04 July 2013; Published online: 30 July 2013.
Edited by:Silvia Carolina Galvan, Universidad Nacional Autonoma de Mexico, Mexico
Reviewed by:Silvio Zaina, University of Guanajuato, Mexico
James DeCaprio, Dana-Farber Cancer Institute, USA
Copyright: © 2013 Kallestad, Woods, Christensen, Gefroh, Balakrishnan and Milavetz. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Barry Milavetz, Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, 501 North Columbia Road, Grand Forks, ND 58203, USA e-mail: email@example.com