Functional domains of the transcription factor USF2: Atypical nuclear localization signals and context-dependent transcriptional activation domains

Xu Luo, Michèle Sawadogo

Research output: Contribution to journalArticle

113 Citations (Scopus)

Abstract

USF is a family of basic helix-loop-helix transcription factors that recognizes DNA-binding sites similar to those of the Myc oncoproteins. Here, various functional domains in the mouse USF2 protein were identified and characterized. Indirect immunofluorescence studies with transiently transfected cells revealed that both the basic region and the highly conserved USF-specific region (USR) are involved in the nuclear localization of USF2. Cotransfection assays with deletion mutants containing the DNA- binding domain of either USF2 or GAL4 identified two distinct transcriptional activation domains in USF2, the USR and the exon 5-encoded region. Activity of the exon 5 activation domain was detectable in both assay systems. Within USF2, however, its potency varied with the conformation induced by the surrounding regions, especially that encoded by alternatively spliced exon 4. In contrast, the USR activated transcription only in its natural context upstream of the USF2 basic region and only with reporter constructs containing the adenovirus major late minimal promoter but not the E1b minimal promoter. However, insertion of an initiator element downstream of the TATA box rescued the activity of the USR on E1b-driven reporters. The USR therefore represents a new type of activation domain whose function depends very strongly on the core promoter context.

Original languageEnglish (US)
Pages (from-to)1367-1375
Number of pages9
JournalMolecular and cellular biology
Volume16
Issue number4
DOIs
StatePublished - Apr 1996

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Nuclear Localization Signals
Transcriptional Activation
Exons
Transcription Factors
Basic Helix-Loop-Helix Transcription Factors
TATA Box
Oncogene Proteins
DNA
Indirect Fluorescent Antibody Technique
Adenoviridae
Binding Sites

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

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title = "Functional domains of the transcription factor USF2: Atypical nuclear localization signals and context-dependent transcriptional activation domains",
abstract = "USF is a family of basic helix-loop-helix transcription factors that recognizes DNA-binding sites similar to those of the Myc oncoproteins. Here, various functional domains in the mouse USF2 protein were identified and characterized. Indirect immunofluorescence studies with transiently transfected cells revealed that both the basic region and the highly conserved USF-specific region (USR) are involved in the nuclear localization of USF2. Cotransfection assays with deletion mutants containing the DNA- binding domain of either USF2 or GAL4 identified two distinct transcriptional activation domains in USF2, the USR and the exon 5-encoded region. Activity of the exon 5 activation domain was detectable in both assay systems. Within USF2, however, its potency varied with the conformation induced by the surrounding regions, especially that encoded by alternatively spliced exon 4. In contrast, the USR activated transcription only in its natural context upstream of the USF2 basic region and only with reporter constructs containing the adenovirus major late minimal promoter but not the E1b minimal promoter. However, insertion of an initiator element downstream of the TATA box rescued the activity of the USR on E1b-driven reporters. The USR therefore represents a new type of activation domain whose function depends very strongly on the core promoter context.",
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