Knock-in Vector for Expression of Insulin-like Growth Factor 1 on the Bovine β-casein Gene Locus

Abstract

The production of therapeutic protein and improve of productivity of the domestic animal from transgenic animal is the major technology of biotechnology. Lactoferrin has its highest content in the colostrum, and is known as the antiviral substance. Insulin like growth factor1 is known to play an important role in the growth of the animal. The objective of this study is construction of knock-in vector that insulin like growth factor1 gene is inserted into the β-casein gene locus for expression of bovine insulin like growth factor1 (bIGF1) on the bovine β-casein gene. The knock-in vector consists of 5’ arm region (1.02 kb), insulin like growth factor 1 cDNA, CMV-EGFP, and 3’ arm region (1.83 kb). To express bIGF1 gene as transgene, the F2A sequence was fused to the 5’ terminal of bIGF1 gene and inserted into exon 7 of the β-casein gene. As a result, the knock-in vector is confirmed that the amino acids are synthesized without termination from the β-casein exon 7 region to the bIGF1 gene. These knock-in vectors may help to create transgenic dairy cattle expressing bovine IGF1 protein in the mammary gland via the expression system of the bovine β-casein gene.