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Drug inhibitors of RNA polymerase II transcription
Abstract:
Transcription by RNA polymerase II occurs after formation of a transcription complex. This complex is assembled in stages by the interaction of transcription factors with the template and/or with each other. We report on the ability of six drugs to inhibit the assembly of the RNA polymerase II transcription complex. Assembly of the complex on the adenovirus major late promoter requires several transcription factors. The normal assembly process requires that the DNA first interact with TFIIA, then with TFIID, and finally with at least four additional transcription factors (one of which is RNA polymerase II). We observed that streptolydigin (10 micrograms/ml) inhibits association of ILA and IID, and at higher concentrations (100 micrograms/ml) inhibits that IIA/IID complex from binding to DNA. Streptovaricin (100 micrograms/ml) appears to inhibit the IIA/IID interaction with DNA and prevents reinitiation (at 500 micrograms/ml). Adriamycin (1 microgram/ml) inhibits the interaction of TFIID with the IIA/DNA complex and inhibits an additional event immediately prior to, or during, elongation. Daunorubicin may be an elongation inhibitor. Heparin at 10 micrograms/ml inhibits further assembly after the IIA/IID/DNA complex has formed, and at 100 micrograms/ml also inhibits a late event in the assembly process and blocks reinitiation. Rifamycin AF/013 (100 micrograms/ml) inhibits the early events necessary to form the IIA/IID/DNA complex and (at 10 micrograms/ml) an assembly event following formation of the IIA/IID/DNA complex. Therefore, these compounds should be useful as probes for further examination of the assembly process.
Insights
Six drugs were tested for their ability to inhibit RNA polymerase II transcription complex assembly. Several compounds, including streptolydigin and adriamycin, were found to disrupt specific stages of this crucial molecular process.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Transcription by RNA polymerase II is a fundamental biological process.
- This process involves the sequential assembly of a transcription complex mediated by transcription factors.
- Understanding transcription complex assembly is key to deciphering gene regulation.
Purpose of the Study:
- To investigate the inhibitory effects of six drugs on RNA polymerase II transcription complex assembly.
- To identify specific stages of transcription complex assembly that can be targeted by small molecules.
- To evaluate the potential of these drugs as research tools for studying transcription.
Main Methods:
- Assessing the impact of various drug concentrations on the assembly of the transcription complex on the adenovirus major late promoter.
- Monitoring the interactions between transcription factors (TFIIA, TFIID) and DNA during complex formation.
- Observing the effects of drugs on transcription initiation and elongation phases.
Main Results:
- Streptolydigin inhibited TFIIA/TFIID association and subsequent DNA binding.
- Streptovaricin and heparin interfered with TFIIA/TFIID/DNA complex formation and reinitiation.
- Adriamycin and Rifamycin AF/013 disrupted TFIID binding and other early/late assembly events, while daunorubicin potentially affected elongation.
Conclusions:
- Several tested drugs effectively inhibit distinct steps in RNA polymerase II transcription complex assembly.
- These inhibitory compounds serve as valuable molecular probes for dissecting the intricate process of transcription initiation.
- Further research using these drugs can elucidate the mechanisms governing transcription factor interactions and complex formation.