Seed-Specific Expression of Apolipoprotein A-IMilano Dimer in Engineered Rice Lines

Abstract

Apolipoprotein A-I_Milano (ApoA-I_M) has been shown to significantly reduce coronary atherosclerotic plaques. However, the preparation of cost-effective pharmaceutical formulations of ApoA-I_M is limited by the high cost and difficulty of purifying the protein and producing the highly effective dimeric form. The aim of this study was to create an expression cassette that specifically drives the expression of dimeric ApoA-I_M in the protein bodies of rice seeds. The ApoA-I_M protein under control of the 13 kDa prolamin promoter is expressed exclusively in its dimeric form within the seeds, and immunocytochemical and immunogold analyses confirmed its expression in different caryopsis tissue such as seed coat, aleurone cell and endosperm, particularly in amyloplast and storage vacuoles. A plant-based ApoA-I_M production system offered numerous advantages over current production systems, including the direct production of the most therapeutically effective dimeric ApoA-I_M forms, long-term protein storage in seeds, and ease of protein production by simply growing plants. Therefore, seeds had the potential to serve as a cost-effective source of therapeutic ApoA-I_M.