Production of biologically active human interferon-α in transgenic rice

Abstract

Interferon-α (IFN-α) is a principle cytokine that plays a key regulatory role in mammalian immune systems. The recombinant DNA of IFN-α is composed of the signal sequence region for rice 10 kDa prolamin cDNA, the amino-terminal region of β-glucuronidase DNA, and the mature polypeptide region of human IFN-αDNA, and is expected to produce a biologically active form of IFN-α. This chimerical DNA for coding IFN-α under the control of a cauliflower mosaic virus 35S promoter and a 5′-intron of rice cytosolic superoxide dismutase gene (sodcC1), was transformed into dwarf rice by an Agrobacterium-mediated system. Three lines of transgenic rice plant expressing various levels of IFN-α polypeptide were finally generated. The expression level of the recombinant polypeptide in each line was analyzed by an IFN-α antiviral activity assay and enzyme immunoassay. Higher expression of IFN-α was achieved in developing seed endosperm in two of transgenic rice lines. The replacement of the native signal peptide of IFN-α with the prolamin signal peptide was effective for transporting the IFN-α polypeptide into the ER-derived protein body of developing seed endosperm. These results suggest that rice can be used to produce many biologically active mammalian proteins that accumulate in target organelles such as protein bodies.