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.

Transcription factor IIA of wheat and human function similarly with plant and animal viral promoters

“…All compounds were of ultrapure quality and were obtained as described previously (11,35). HeLa cell nuclear extracts and fractions C, D, DB, DE, F, and FS, as well as wheat germ nuclear extracts and fractions F, K, KD, and KB were prepared as described (refs.…”

“…HeLa nuclear extracts, prepared from 2.4 x 10 cells, were fractionated by chromatography on phosphocellulose (11,25). TFIIA was further purified as described (ref.…”

“…Reactions contained 300 uM CTP and UTP, 20 .M GTP, 400 ytM ATP, and 5.0 4Ci a-32P-GTP. Transcription reactions were processed and analyzed by denaturing (urea) polyacrylamide gel electrophoresis (PAGE) and autoradiography as described (11,13,35). 32P-labelled fragments from an Msp I restriction digest of pBR322 DNA were used as size markers (New England Biolabs).…”

“…Reconstituted in vitro transcription systems using purified proteins and/or altered templates have facilitated delineation of the steps in assembly of DNA:protein transcription complexes. These steps include interactions between proteins, proteins and DNA, and also conformational transitions (4)(5)(6)(7)(8)(9)(10)(11). The observations that TFs from widely divergent species are functionally similar in heterologous systems (12)(13)(14)(15)(16) suggest that the basic mechanisms affecting transcriptional gene regulation may be common to all eucaryotes.…”

Transcription and Translation Inhibitors in Cancer Treatment

“…At the second step of the transcription process, Pol II inhibitors block the formation of the Pol II-transcription factor complexes. The study of these inhibitors dates back to the late 80's and is still a subject of study today (Logan et al, 1989;Sharma et al, 2019) (Figure 1). The last step that can be acted upon at transcription level is the elongation step.…”