Priming affects the activity of a specific region of the promoter of the human beta interferon gene.

Abstract

Treatment of Daudi or HeLa cells with human interferon (IFN) alpha 8 before induction with either poly(I)-poly(C) or Sendai virus resulted in an 8- to 100-fold increase in IFN production. The extent of priming in Daudi cells paralleled the increase in the intracellular content of IFN-beta mRNA. IFN-alpha mRNA remained undetectable in poly(I)-poly(C)-treated Daudi cells either before or after priming. An IFN-resistant clone of Daudi cells was found to produce 4- to 20-fold more IFN after priming, indicating that priming was unrelated to the phenotype of IFN sensitivity. IFN treatment of either Daudi or HeLa cells transfected with the human IFN-beta promoter (-282 to -37) linked to the chloramphenicol acetyltransferase (CAT) gene resulted in an increase in CAT activity after induction with poly(I)-poly(C) or Sendai virus. A synthetic double-stranded oligonucleotide corresponding to an authentic 30-base-pair (bp) region of the human IFN-beta promoter between positions -91 and -62 was found to confer virus inducibility upon the reporter CAT gene in HeLa cells. IFN treatment of HeLa cells transfected with this 30-bp region of the IFN-beta promoter in either the correct or reversed orientation also increased CAT activity upon subsequent induction. IFN treatment alone had no detectable effect on the activity of either the 30-bp region or the complete human IFN promoter.

Mice devoid of interferon regulatory factor 1 (IRF-1) show normal expression of type I interferon genes.

“…Also in agreement with Matsuyama et al (1993), the reduced IFN gene expression observed in poly(I)-poly(C)induced IRF-10/0 cells was overcome by pre-treating, i.e. priming the cells with type I IFN (Stewart et al, 1971;Raj and Pitha, 1981;Enoch et al, 1986;Dron et al, 1990) (Figure 7). To determine whether the restoration of full inducibility of MEFs by priming with IFN involved protein synthesis, the effect of cycloheximide was determined.…”

“…IRF-1o/o MEFs in cell culture, while responding normally to NDV induction, show diminished expression of IFN-ax and IFN-3 mRNA after poly(I).poly(C) induction (Matsuyama et al, 1993;this paper). Priming with type I IFN, which acts at the transcriptional level (Dron et al, 1990), increases the expression in both normal and mutant cells, bringing them to about the same level. An important conclusion of this finding is that even in MEFs a direct interaction of IRF-I with the IFN promoter is not essential.…”

Deficient signaling in mice devoid of double-stranded RNA-dependent protein kinase.

“…In cells stimulated with TNF-a, NF-c1B was activated to the same extent in wildtype, heterozygous and knockout cells (lanes 10-12). Interestingly, when the MEFs were pretreated (primed; Stewart 1986; Dron et al, 1990) with type I or type II IFN, the activation of NF-kcB in Pkro/o was restored to about half the wild-type level ( Figure 4B).…”

Promotion of TRAIL/Apo2L‐induced apoptosis by low‐dose interferon‐β in human malignant melanoma cells

“…IFN‐β pretreatment sensitizes human melanoma cells to TRAIL‐induced apoptosis (Chawla‐Sarkar, Leaman, Jacobs, & Borden, ; Micali et al, ). Previously, it has been demonstrated that the pretreatment with small amounts of IFN‐β promotes the double‐stranded RNA‐ or virus‐induced cytokine productions, as well as IFN‐β in human fibroblasts (Dron, Lacasa, & Tovey, ; Sano et al, ). This priming effect is characteristic of type 1 IFNs.…”