Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1992 Aug 15;89(16):7340–7344. doi: 10.1073/pnas.89.16.7340

Dual role of the nucleolar transcription factor UBF: trans-activator and antirepressor.

A Kuhn 1, I Grummt 1
PMCID: PMC49705  PMID: 1502143

Abstract

In a reconstituted system consisting of partially purified RNA polymerase I (pol I) and the initiation factors TIF-IA, TIF-IB, and TIF-IC, the nucleolar factor UBF (upstream binding factor) stimulates transcription from the rRNA-encoding DNA (rDNA) promoter at least 50-fold. This activation is not observed at high template concentrations or in the presence of highly purified pol I. Template commitment experiments suggest that UBF activates transcription by relieving inhibition exerted by a negative-acting factor(s) in the polymerase fraction that competes for TIF-IB binding to the rDNA promoter and prevents the formation of preinitiation complexes. Using purified histone H1 bound to DNA as a model for the repressed state of the rDNA promoter, we show that UBF counteracts H1-mediated repression of pol I transcription. The implications of these findings are discussed with respect to the protein-protein and protein-DNA interactions at the rDNA promoter and the possible involvement of UBF in control of ribosomal gene transcription.

Full text

PDF
7340

Images in this article

7341Image
on p.7341
7341Image
on p.7341
7342Image
on p.7342
7342Image
on p.7342
7343Image
on p.7343

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bell S. P., Learned R. M., Jantzen H. M., Tjian R. Functional cooperativity between transcription factors UBF1 and SL1 mediates human ribosomal RNA synthesis. Science. 1988 Sep 2;241(4870):1192–1197. doi: 10.1126/science.3413483. [DOI] [PubMed] [Google Scholar]
  2. Clos J., Buttgereit D., Grummt I. A purified transcription factor (TIF-IB) binds to essential sequences of the mouse rDNA promoter. Proc Natl Acad Sci U S A. 1986 Feb;83(3):604–608. doi: 10.1073/pnas.83.3.604. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Croston G. E., Kerrigan L. A., Lira L. M., Marshak D. R., Kadonaga J. T. Sequence-specific antirepression of histone H1-mediated inhibition of basal RNA polymerase II transcription. Science. 1991 Feb 8;251(4994):643–649. doi: 10.1126/science.1899487. [DOI] [PubMed] [Google Scholar]
  4. Gokal P. K., Mahajan P. B., Thompson E. A. Hormonal regulation of transcription of rDNA. Formation of initiated complexes by RNA polymerase I in vitro. J Biol Chem. 1990 Sep 25;265(27):16234–16243. [PubMed] [Google Scholar]
  5. Jantzen H. M., Admon A., Bell S. P., Tjian R. Nucleolar transcription factor hUBF contains a DNA-binding motif with homology to HMG proteins. Nature. 1990 Apr 26;344(6269):830–836. doi: 10.1038/344830a0. [DOI] [PubMed] [Google Scholar]
  6. Learned R. M., Learned T. K., Haltiner M. M., Tjian R. T. Human rRNA transcription is modulated by the coordinate binding of two factors to an upstream control element. Cell. 1986 Jun 20;45(6):847–857. doi: 10.1016/0092-8674(86)90559-3. [DOI] [PubMed] [Google Scholar]
  7. McStay B., Hu C. H., Pikaard C. S., Reeder R. H. xUBF and Rib 1 are both required for formation of a stable polymerase I promoter complex in X. laevis. EMBO J. 1991 Aug;10(8):2297–2303. doi: 10.1002/j.1460-2075.1991.tb07766.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Reeder R. H. Regulatory elements of the generic ribosomal gene. Curr Opin Cell Biol. 1989 Jun;1(3):466–474. doi: 10.1016/0955-0674(89)90007-0. [DOI] [PubMed] [Google Scholar]
  9. Schnapp A., Clos J., Hädelt W., Schreck R., Cvekl A., Grummt I. Isolation and functional characterization of TIF-IB, a factor that confers promoter specificity to mouse RNA polymerase I. Nucleic Acids Res. 1990 Mar 25;18(6):1385–1393. doi: 10.1093/nar/18.6.1385. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Schnapp A., Grummt I. Transcription complex formation at the mouse rDNA promoter involves the stepwise association of four transcription factors and RNA polymerase I. J Biol Chem. 1991 Dec 25;266(36):24588–24595. [PubMed] [Google Scholar]
  11. Schnapp A., Pfleiderer C., Rosenbauer H., Grummt I. A growth-dependent transcription initiation factor (TIF-IA) interacting with RNA polymerase I regulates mouse ribosomal RNA synthesis. EMBO J. 1990 Sep;9(9):2857–2863. doi: 10.1002/j.1460-2075.1990.tb07475.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Smith S. D., Oriahi E., Lowe D., Yang-Yen H. F., O'Mahony D., Rose K., Chen K., Rothblum L. I. Characterization of factors that direct transcription of rat ribosomal DNA. Mol Cell Biol. 1990 Jun;10(6):3105–3116. doi: 10.1128/mcb.10.6.3105. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Wandelt C., Grummt I. Formation of stable preinitiation complexes is a prerequisite for ribosomal DNA transcription in vitro. Nucleic Acids Res. 1983 Jun 11;11(11):3795–3809. doi: 10.1093/nar/11.11.3795. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES