Interferon-γ-mediated inhibition of cyclin A gene transcription is independent of Individual cis-acting elements in the cyclin a promoter

Nicholas E.S. Sibinga, Hong Wang, Mark A. Perrella, Wilson O. Endege, Cam Patterson, Masao Yoshizumi, Edgar Haber, Mu En Lee

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Interferons (IFNs) affect cellular functions by altering gene expression. The eukaryotic cell cycle is governed in part by the periodic transcription of cyclin genes, whose protein products associate with and positively regulate the cyclin-dependent kinases. To understand better the growth inhibitory effect of IFN-γ on vascular smooth muscle cells (VSMCs), we compared the expression and activity of G1 and S phase cyclins in control and IFN-γ-treated VSMCs. IFN-γ treatment did not inhibit the G1 cyclins but did decrease cyclin A protein, mRNA, and associated kinase activity by 85, 90, and 90%, respectively. Nuclear run-on and mRNA stability determinations indicated that this decrease was the result of transcriptional inhibition. To investigate the molecular basis of this inhibition, we examined protein-DNA interactions involving the cyclin A promoter. Electromobility shift assays showed little change with IFN-y treatment in the binding of nuclear proteins to isolated γ, N-F-Y, and CDE elements. In vivo genomic footprinting indicated that IFN-γ treatment changed the occupancy of chromosomal NF-Y and CDE sites slightly and did not affect occupancy of the ATF site. In a previous study of transforming growth factor-β1-mediated inhibition of the cyclin A promoter, we mapped the inhibitory effect to the ATF site; in the present study of IFN-γ treatment, functional analysis by transient transfection showed that inhibition of the cyclin A promoter persisted despite mutation of the ATF, NF-Y, or CDE elements. We hypothesize that FN-γ inhibits cyclin A transcription by modifying co-activators or general transcription factors within the complex that drives transcription of the cyclin A gene.

Original languageEnglish (US)
Pages (from-to)12139-12146
Number of pages8
JournalJournal of Biological Chemistry
Issue number17
StatePublished - Apr 23 1999
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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