Tilapia IFP35 is differently induced by three subgroups of type I IFNs via the JAK-STAT signaling.

Interferons (IFNs) trigger effective antiviral responses by activating the expression of a series of interferon-stimulated genes (ISGs), and interferon-induced protein 35 (IFP35) has been identified as a typical ISG in mammals and fish. Nevertheless, it is required to compare distinct responses of IFP35 to different subgroups of type I IFNs in fish. Here, we cloned IFP35 gene (named as On-IFP35) from tilapia, and syntenic analysis showed that On-IFP35 gene was found in a locus conserved in cartilaginous and bony fishes. Expression analyses showed that On-IFP35 was detectable in all organs/tissues tested except for spleen, and was highly induced after poly (I:C) treatment in vivo and in vitro. In addition, the expression of On-IFP35 was differently induced by three subgroups of type I IFNs, and these induction effect depended on the JAK-STAT signaling. Consistently, luciferase activity analysis revealed that the promoter of On-IFP35 was differently activated by three subgroups of type I IFNs via a ISRE site. The present results thus contribute to better understanding of the transcriptional regulation of fish IFP35 in type I IFN response.