Hypocalcemic effect of recombinant Saccharomyces cerevisiae expressing salmon calcitonin / 解放军医学杂志

ABSTRACT

Objective To investigate the effect of gavaged yAGA2-sCT, a recombinant Saccharomyces cerevisiae which expressed salmon calcitonin on its surface, on serum calcium concentration of rats. Methods The sCT gene was artificially synthesized in advance and cloned into the pYD1 vector, a kind of surface displaying plasmid, to yield pYD1-sCT. The recombinant plasmid pYD1-sCT was transformed into S. cerevisiae EBY100 by LiAC method and achieved yAGA2-sCT. The sCT protein, which was expressed on the surface of recombinant S. cerevisiae yAGA2-sCT, was indirectly labeled with FITC. Labeled yeast was immediately detected under the fluorescent microscope. Before being gavaged to rats, recombinant yeast was frozen and vacuum-dried. Lyophilized yeast yAGA2-sCT was administered to rats in dosage of 0.1g/kg, 0.5g/kg and 5.0g/kg, respectively, with 6 rats in each group. Positive drug group (200mU/kg calcitonin via hypodermic injection) and two conditional control groups (being gavaged 5g/kg yAGA2-sCT and 30?g/kg calcitonin, respectively) were acted as controls. The serum was collected from canthus venous plexus and the calcium concentration was immediately measured by automatic biochemical analyzer. Results The sCT protein was successfully expressed on the surface of recombinant yAGA2-sCT, and FITC-labeled yAGA2-sCT was observed under the fluorescent microscope. The recombinant S. cerevisiae yAGA2-sCT was able to reduce the serum calcium concentration of rats in a dose-dependent manner. In the three subgroups, the hypocalcemic effect of high-dosage subgroup, with 5g/kg lyophilized yAGA2-sCT, was the highest (P