The cell cycle regulatory factor TAF1 stimulates ribosomal DNA transcription by binding to the activator UBF

Curr Biol. 2002 Dec 23;12(24):2142-6. doi: 10.1016/s0960-9822(02)01389-1.

Abstract

Control of ribosome biogenesis is a potential mechanism for the regulation of cell size during growth, and a key step in regulating ribosome production is ribosomal RNA synthesis by RNA polymerase I (Pol I). In humans, Pol I transcription requires the upstream binding factor UBF and the selectivity factor SL1 to assemble coordinately on the promoter. UBF is an HMG box-containing factor that binds to the rDNA promoter and activates Pol I transcription through its acidic carboxy-terminal tail. Using UBF (284-670) as bait in a yeast two-hybrid screen, we have identified an interaction between UBF and TAF1, a factor involved in the transcription of cell cycle and growth regulatory genes. Coimmunoprecipitation and protein-protein interaction assays confirmed that TAF1 binds to UBF. Confocal microscopy showed that TAF1 colocalizes with UBF in Hela cells, and cell fractionation experiments provided further evidence that a portion of TAF1 is localized in the nucleolus, the organelle devoted to ribosomal DNA transcription. Cotransfection and in vitro transcription assays showed that TAF1 stimulates Pol I transcription in a dosage-dependent manner. Thus, TAF1 may be involved in the coordinate expression of Pol I- and Pol II-transcribed genes required for protein biosynthesis and cell cycle progression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Cycle / physiology
  • Cell-Free System
  • Cells, Cultured
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / metabolism*
  • DNA, Ribosomal / genetics*
  • DNA, Ribosomal / metabolism
  • DNA-Binding Proteins
  • HeLa Cells
  • Histone Acetyltransferases
  • Histone Chaperones
  • Humans
  • Mutation
  • Pol1 Transcription Initiation Complex Proteins / genetics
  • Pol1 Transcription Initiation Complex Proteins / metabolism*
  • RNA Polymerase I / genetics
  • RNA Polymerase I / metabolism
  • RNA Polymerase II / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • TATA-Binding Protein Associated Factors / genetics
  • TATA-Binding Protein Associated Factors / metabolism
  • Transcription Factor TFIID / genetics
  • Transcription Factor TFIID / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic / physiology
  • Transfection
  • Two-Hybrid System Techniques

Substances

  • Chromosomal Proteins, Non-Histone
  • DNA, Ribosomal
  • DNA-Binding Proteins
  • Histone Chaperones
  • Pol1 Transcription Initiation Complex Proteins
  • Recombinant Proteins
  • SET protein, human
  • TATA-Binding Protein Associated Factors
  • Transcription Factor TFIID
  • Transcription Factors
  • transcription factor UBF
  • Histone Acetyltransferases
  • TATA-binding protein associated factor 250 kDa
  • RNA Polymerase II
  • RNA Polymerase I