Roles of Stat1, Stat2, and interferon regulatory factor-9 (IRF-9) in interferon tau regulation of IRF-1. Academic Article uri icon


  • Interferon tau (IFNtau) is the pregnancy recognition signal produced by the conceptus trophectoderm and acts in a paracine manner on the ovine endometrium to increase expression of IFN-stimulated genes primarily in the stroma and deep glandular epithelium, including IFN regulatory factor-1 (IRF-1). The roles of Stat1, Stat2, and IRF-9 in IFNtau regulation of IRF-1 expression were determined using human stromal fibroblasts lacking specific IFN signaling components or complemented with specific Stat1 mutants. In parental (2fTGH) cells treated with IFNtau, Stat1alpha/beta was tyrosine phosphorylated by 15 min, and IRF-1 mRNA and protein increased from 0 to 6 h, was maximal at 6 h, and decreased to 24 h. In contrast, IFNtau did not affect IRF-1 expression in Stat1- and Stat2-deficient cells or in Stat1-deficient cells complemented with Stat1 Y701Q or Stat1 R602L mutants. In Stat1-deficient cells complemented with the Stat1 S727A mutant, Stat1alpha, or Stat1beta and treated with IFNtau, IRF-1 increased from 0 to 6 h, was maximal at 6 h, and decreased thereafter. In IRF-9-deficient cells stimulated with IFNtau, IRF-1 increased from 0 to 6 h but did not exhibit the sharp decline from 6 to 12 h observed in other cells. Collectively, results indicate that IFNtau effect on IRF-1 expression is primarily regulated by tyrosine-phosphorylated Stat1alpha or Stat1beta dimers, whereas the decline of IRF-1 after 6 h of IFNtau treatment is regulated by IRF-9.

published proceedings

  • Biol Reprod

author list (cited authors)

  • Stewart, M. D., Choi, Y., Johnson, G. A., Yu-Lee, L., Bazer, F. W., & Spencer, T. E.

citation count

  • 36

complete list of authors

  • Stewart, M David||Choi, Youngsok||Johnson, Greg A||Yu-Lee, Li-yuan||Bazer, Fuller W||Spencer, Thomas E

publication date

  • February 2002