Related Experiment Video
Updated: Aug 2, 2026

Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
Published on: March 2, 2014
Repression of virus-induced interferon A promoters by homeodomain transcription factor Ptx1
S Lopez1, M L Island, J Drouin
1Laboratoire de Régulation de la Transcription et Maladies Génétiques, CNRS, UPR 2228, UFR Biomédicale des Saints-Pères, Université René Descartes, 75270 Paris Cedex 06, France. Sebastien.Navarro@biomedicale.univ-paris5.fr
Abstract:
Interferon A (IFN-A) genes are differentially expressed after virus induction. The differential expression of individual IFN-A genes is modulated by substitutions in the proximal positive virus responsive element A (VRE-A) of their promoters and by the presence or absence of a distal negative regulatory element (DNRE). The functional feature of the DNRE is to specifically act by repression of VRE-A activity. With the use of the yeast one-hybrid system, we describe here the identification of a specific DNRE-binding protein, the pituitary homeobox 1 (Ptx1 or Pitx1). Ptx1 is detectable in different cell types that differentially express IFN-A genes, and the endogenous Ptx1 protein binds specifically to the DNRE. Upon virus induction, Ptx1 negatively regulates the transcription of DNRE-containing IFN-A promoters, and the C-terminal region, as well as the homeodomain of the Ptx1 protein, is required for this repression. After virus induction, the expression of the Ptx1 antisense RNA leads to a significant increase of endogenous IFN-A gene transcription and is able to modify the pattern of differential expression of individual IFN-A genes. These studies suggest that Ptx1 contributes to the differential transcriptional strength of the promoters of different IFN-A genes and that these genes may provide new targets for transcriptional regulation by a homeodomain transcription factor.
Related Concept Videos
RNA Polymerase II Accessory Proteins
Co-activators and Co-repressors
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Inhibitors of Viral Protein Synthesis
Inhibitors Of Virion Release
Inhibitors of Virion Maturation and Assembly

