Fusion Expression And Activity Of The SCT And Ogp Test

Osteoporosis is a disease of bone metabolic disorder, the incidence of which increases sharply in old people. Calcitonin (CT) is a peptide hormone containing 32 amino acid that can restrain the activity of osteoclasts and stimulate the activity of osteoblasts. The activity of Salmon calcitonin is most remarkable among all kinds of CT. Osteogenic Growth Peptide (OOP) is a peptide hormone with 14 amino acid. It is an autocrine mitogen for osteoblastic and firbroblastic cells. It also stimulates alkaline phosphatase (ALP) activity and matrix mineralization. These two peptides have a clinical role in osteoporosis therapy, however, the source of nature sCT and OOP is rare and the cost of chemical synthesis is relatively expensive. We have obtained sCT+OGP (salmon Calcitonin + Osteogenic Growth Peptide) fusion protein in pichia yeast, and proved its activity of inhibiting osteoclasts as well as stimulating osteoblasts. We hope the protein be useful in the therapy of osteoporosis.Six sCT and OGP DNA segments were chemically synthesized and ligated in a certain proportion into a yeast vector pPIC9. The fusion gene of sCT+OGP was obtained, which was confirmed by sequence analysising. The recombinant plasmid was transformed into pichia pastoris GS115. Finally, we got one stable lineage of expressing protein. The primarily purified fusion protein can increase the proliferation of osteoblastic and fibroblastic cells, stimulate the ALP activity and decrease the level of serum calcium by the experiments in vitro and in vivo. Our study provides a basis for further research of the clinical application in osteoporosis therapy with sCT and OGP fusion protein.