Upregulation of a spliced variant of human interferon regulatory factor 3 through binding of the transcription factor Sp1 to the promoter

Zhu,Liang‑Hua; Qiu,Ling‑Zhi; Ren,Wei; Zhou,Guo‑Ping

doi:10.3892/br.2013.198

Upregulation of a spliced variant of human interferon regulatory factor 3 through binding of the transcription factor Sp1 to the promoter

Authors:
- Liang‑Hua Zhu
- Ling‑Zhi Qiu
- Wei Ren
- Guo‑Ping Zhou
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Affiliations: Department of Pediatrics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
Published online on: November 6, 2013 https://doi.org/10.3892/br.2013.198
Pages: 142-146

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Abstract

Interferon regulatory factor 3 (IRF‑3) plays an important role in host defense against viral and bacterial infection. IRF‑3 includes a variety of spliced variants, which may regulate the transcription of IRF‑3. We previously identified two novel IRF‑3 spliced variants, Int2V1 and Int2V2, starting from intron 2 of the wild‑type of IRF‑3. However, the mechanism through which the IRF‑3 spliced variants regulate transcription has not been elucidated. In this study, we demonstrated that the transcription factor Sp1 upregulates the basal transcriptional activity of IRF‑3 Int2V1. By transient transfection analysis, we demonstrated that the overexpression of Sp1 led to positive regulation, whereas knocking down of the endogenous Sp1 resulted in repression of IRF‑3 promoter activity. Electrophoretic gel mobility shift assays and chromatin immunoprecipitation assays demonstrated that Sp1 interacted with the IRF‑3 promoter in vitro and in vivo. These results suggested that Sp1 positively regulated the transcription of a spliced variant of IRF‑3 through directly binding to the Sp1 consensus binding site.

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