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Histone hyperacetylation during SV40 transcription is regulated by p300 and RNA polymerase II translocation

Lata Balakrishnan1, Barry Milavetz

  • 1Department of Biochemistry and Molecular Biology, University of North Dakota, Grand Forks, ND 58203, USA.

Journal of Molecular Biology
|July 31, 2007
PubMed

Insights

RNA polymerase II (RNAPII) translocation inhibitors and p300 siRNA affect histone modifications in simian virus 40 minichromosomes. Histone acetylation/deacetylation depends on p300 and an unknown histone deacetylase during RNAPII translocation.

Area of Science:

  • Molecular Biology
  • Epigenetics
  • Biochemistry

Background:

  • Simian virus 40 (SV40) minichromosomes are a model for studying eukaryotic transcription.
  • RNA polymerase II (RNAPII) plays a central role in gene expression.
  • Histone modifications, such as acetylation, regulate chromatin structure and gene accessibility.

Purpose of the Study:

  • To investigate the impact of RNAPII translocation inhibitors and p300 targeting on histone modifications in transcribing SV40 minichromosomes.
  • To elucidate the roles of p300 and associated factors in regulating histone acetylation and deacetylation during transcription.

Main Methods:

  • Treatment of SV40 minichromosomes with alpha amanitin and 5,6-dichloro-1-beta-D-ribobenzimidazole (DRB) as RNAPII inhibitors.
  • Utilizing small interfering RNA (siRNA) targeting the p300 protein.
  • Assessing the occupancy of RNAPII, p300, and histone modifications (hyperacetylated and unmodified H3/H4) using chromatin analysis.

Main Results:

  • Alpha amanitin treatment reduced RNAPII promoter occupancy, caused p300 loss, and increased unmodified histones.
  • DRB treatment showed minimal effect on RNAPII/p300 but increased unmodified histones.
  • p300 siRNA significantly decreased late transcription, p300, and hyperacetylated histones.

Conclusions:

  • Histone hyperacetylation and deacetylation in transcribing SV40 minichromosomes are dependent on p300.
  • An unknown histone deacetylase associated with the RNAPII complex coordinates histone modification during translocation.

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