Characterization of murine interferon-alpha 12 (MuIFN-α12): Biological activities and gene expression

Interferon alpha (IFN-α) belongs to the type I interferon family and consists of multiple subtypes in many species. In the mouse, there are at least 14 IFN-α genes and 3 IFN-α pseudogenes, the most recently identified of which are murine interferon-alpha 12 (MuIFN-α12), MuIFN-α13 and MuIFN-α14. To further study the biological activities of MuIFN-α12, we have produced a recombinant MuIFN-α12 (rMuIFN-α12) protein using COS-1 cells. rMuIFN-α12 was found to inhibit the growth of murine myeloid leukemia JCS cells. Flow cytofluorometric analysis with propidium iodide staining showed that the growth inhibitory activity of rMuIFN-α12 may be caused by the induction of apoptosis. Flow cytofluorometric analysis also revealed that rMuIFN-α12 was able to up-regulate the expression of MHC-I on both JCS cells and primary macrophages. Functional studies indicated that a MuIFN-α12 transgene could induce an anti-viral state in L929 cells against Influenza A virus. Moreover, expression of MuIFN-α12 was not detectable by RT-PCR in untreated, Influenza A virus infected, polyI:polyC induced L929 cells, or in a wide range of normal murine tissues. Taken together, this data shows that MuIFN-α12 is a protein with all the biological traits of a type I IFN.