Journal Article

Disruption of transcription in vitro and gene expression in vivo by DNA adducts derived from a benzo[a]pyrene diol epoxide located in heterologous sequences.

A P Butler, D G Johnson, A P Kumar, S Narayan, S H Wilson and M C MacLeod

in Carcinogenesis

Volume 18, issue 2, pages 239-244
Published in print February 1997 | ISSN: 0143-3334
Published online February 1997 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/18.2.239
Disruption of transcription in vitro and gene expression in vivo by DNA adducts derived from a benzo[a]pyrene diol epoxide located in heterologous sequences.

More Like This

Show all results sharing this subject:

  • Clinical Cytogenetics and Molecular Genetics

GO

Show Summary Details

Preview

Previous studies indicated a high affinity of the transcription factor Sp1 for DNA adducts derived from benzo[a]pyrene diol epoxide (BPDE) in sequences that are not normal binding sites for Sp1. We tested for functional effects of this phenomenon in three systems in which transcription is Sp1-dependent. In an in vitro, Sp1-dependent transcription system addition of heterologous plasmid DNA containing BPDE adducts abolished production of a specific run-off transcript. This inhibition was not seen with unmodified plasmid DNA, and could be overcome by addition of purified Sp1 protein. In SL2 insect cells, high-level expression of an Sp1-dependent reporter gene, which was dependent on co-transfection of an Sp1 expression vector, was inhibited >95% by co-transfection of heterologous DNA containing BPDE adducts. This inhibition could be partially overcome by increasing the amount of the Sp1 expression vector in the transfections. In human C33A cells, expression of a transfected reporter gene driven by a GC box containing fragment of the human E2F1 promoter was enhanced by co-transfection of an Sp1 expression plasmid. Expression was inhibited 3-6-fold by co-transfection of heterologous DNA containing BPDE-DNA adducts. A similar inhibition was seen in human SAOS-2 cells, which lack functional p53 protein. These data are consistent with functionally significant sequestration of the Sp1 transcription factor by BPDE-DNA adducts in all three systems. Altered availability of transcription factors such as Sp1 in carcinogen-treated cells may disrupt patterns of gene expression.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.