Secretion Expression Of HIGF-I By Bombyx Mori Silkglands Bioreactor And Its Bioactivity

Insulin-like growth factor-I (hIGF-I) has the effct of promoting growth. In order tosecrete the expressed Insulin-like growth factor-I (hIGF-I) in silk gland of transgenicsilkworms into the sericin layer of the cocoon. In our previous studies, a hIGF-I genecontrolled by the sericin promoter with the signaling peptide DNA sequence of fibroinheavy chain、a neomycin resistance gene (neo) under the control of a immediate earlygene (ie-1) of baculovirus were used to construct transgenic vectorpiggyA3GFP-serHS-IGF-I-ie-neo. In this studies, the transgenic vectorpiggyA3GFP-serHS-IGF-I-ie-neo was introduced into the eggs of silkworm bysperm-mediated method. Transgenic silkworms were obtained by screening with G418,fluorescence observation, and further confirmed by PCR and Dot blotting. And werereared to the G8generation. The degummed solution of the transgenic silkworm cocoonof G8generation was precipitated by adjusting pH to isoelectric point, and the contentof the hIGF-I estimated by ELISA was approximately162.7ng/g.To analyze the biological activity of the sericin extract from transgenic hIGF-Isilkworm cocoons, type I diabetes mice (TIDM) were induced by the injection ofstreptozotocin. TIDM mice were orally administered the sericin extract from thecocoons of the transgenic silkworms (300μL,containing hIGF-I25.42ng).6days later,the blood glucose levels were significantly reduced. Compared with model group, thenon-transgenic group, the wight of the mice in orally administered with the sericinextract from the cocoons of the transgenic silkworms group were improved7days later.Routine blood indices and blood biochemistry indices were measured with ahematological analyzer and an automatic biochemical analyzer respectively, the resultsshowed that routine blood indices and blood biochemistry indices of the mice in orallyadministered with the sericin extract from the cocoons of the transgenic silkwormsgroup were normal, suggesting that the sericin extract from the cocoons of the transgenic hIGF-I gene silkworms can be used as a novel oral therapeutic drug of type Idiabetes.