Tissue Specific Expression of Human Calcitonin Gene in Potato Tubers by an Organ Specific Promoter

To increase the production level of heterologous proteins in plants, strategies such as choice of strongerpromoters, optimization of codon usage and specific localization of foreign proteins are of major concern.Calcitonin (CT), a 32 amino acid polypeptide is a powerful and specific inhibitor of bone resorption and isused to treat several human diseases. Calcitonin activity is not species-specific which make it possible toproduce in various animal sources, however, antibody formation in the prolonged application of animal CTleads to gradual decrease or loss of activity. That is why the long term treatment of human patients with CTrequires homologous calcitonin. In this study, a human calcitonin (hCT) gene, driven by two different promoters (granule bound starch synthase I and Cauliflower mosaic virus 35S) was expressed in potato plants, using Agrobacterium-mediated transformation. Molecular analysis, including PCR, RT-PCR, Northerndot blot hybridizations showed that hCT could be successfully transcribed in transgenic potato plants. Theimmunoassay results showed that tissue specific expression in potato, led to almost five-fold more hCTaccumulation when compared to the constitutively expression in all plant tissues.