Poster: Regulation of gene expression

Abs # 779: Analysis of the regulation of human Interleukin-10 transgene expression in plants

Presenter:	Menassa, Rima , menassar@agr.gc.ca
Authors	Menassa, Rima  (A)   Chen, Ling  (A)   Zhang, Yun  (A)
Affiliations:	(A): Agriculture and Agri-Food Canada

During the past few years, a wide variety of recombinant proteins have been expressed in plants. Some proteins such as the reporter proteins GUS and GFP accumulate to high levels in plants, while others accumulate to very low levels. Inherent properties of these proteins, as well as the subcellular localisation affect their accumulation levels. However, protein turnover is probably the most important factor in determining overall levels. The human interleukin-10 protein (IL-10) a labile protein with a half-life in vivo of 30 minutes. Furthermore, IL-10 requires post-translational modifications and assembly, and is a good representative of other therapeutic proteins. We have expressed IL-10 in tobacco by targeting it to the apoplast, ER, chloroplasts and mitochondria. We have also used different promoters, translation enhancers, 3'UTRs and protein fusions to enhance accumulation levels of this protein. All these approaches have resulted in the generation of stable transgenic tobacco lines with a variable accumulation of IL-10 of 0.0001% to 0.01% total soluble protein (TSP). However, for production and purification from plant tissues to be economic, levels close to 1% TSP are required. The purpose of this study is to develop an understanding of the regulation of recombinant protein expression in plants, particularly identifying the step that limits the accumulation of recombinant proteins.