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Molecular cloning and functional characterization of porcine IFN-β promoter stimulator 1 (IPS-1)

Wang, Dang, Fang, Liurong, Li, Tingting, Luo, Rui, Xie, Lilan, Jiang, Yunbo, Chen, Huanchun, Xiao, Shaobo
Veterinary immunology and immunopathology 2008 v.125 no.3-4 pp. 344-353
swine, immune system, interferons, receptors, immunity, immune response, biochemical pathways, cell physiology, signal transduction, molecular genetics, molecular cloning, complementary DNA, open reading frames, amino acid sequences, DNA-binding domains, messenger RNA, tissue distribution, species differences, phylogeny
The IFN-β promoter stimulator 1 (IPS-1), also known as MAVS/VISA/Cardif, is an adaptor molecule for the retinoic-acid-inducible protein I (RIG-I) or melanoma-differentiation-associated gene 5 (MDA5) that recognizes intracellular double-stranded RNA (dsRNA) and triggers a signal for producing type I IFN. In the present study, porcine IPS-1 cDNA was cloned, using RT-PCR coupled with rapid amplification of cDNA ends (RACE)-PCR, from porcine peripheral blood mononuclear cells. The open reading frame of porcine IPS-1 consists of 1575bp encoding 524 amino acids. The putative porcine IPS-1 protein contains a N-terminal CARD-like domain, a central proline-rich domain, a C-terminal transmembrane domain, and exhibits similarity to mouse, rat, monkey, human and cattle counterparts, ranging from 59% to 79%. Semi-quantitative RT-PCR showed that porcine IPS-1 mRNA was widely expressed in different tissues. Porcine kidney (PK-15) cells transfected with a DNA construct encoding porcine IPS-1 produced type I IFN, and activated IRF3 and NF-κB. Deletion mutant analyses further revealed that both the CARD-like domain and transmembrane domain are essential for these functions. In addition, poly(I:C)-induced porcine IFN-β promoter activation in PK-15 cells was significantly reduced by siRNA targeting IPS-1, indicating that IPS-1 is an important immunoregulator in the porcine innate immune system. The availability of porcine IPS-1 and establishment of its function in the type I IFN signaling pathway provides a useful molecule for defining its role during the course of pig infectious diseases.