Studies on the isolation of factors activating insulin-like growth factor II(IGF-II)

Insulin-like growth factor Ⅱ(IGF-Ⅱ) is a fetal growth factor which is known to act on fetal development and differentiation. Although IGF-Ⅱ is structurally related to insulin and IGF-Ⅰ, its physiological function is not fully understood. The genomic structure of the IGF-Ⅱ gene spans about 35 kb which includes nine exoms and four promoters. High levels of IGF-ⅡmRNAs have been reported in many tumors and tumor cell lines. They arise from the promoters associated with exons 5 and 6 that are expressed in fetal liver. We espressed IGF-Ⅱ and HBV-X in E.coli in the form of fusion protein with β-galactosidase, and isolated each proteins as pure form. The CAT assay using the deletion mutants of human IGF-Ⅱ promoter 4 showed that there are several regulatory elements within promoter 4. We also treated HBV-X and okadaic acid, tumor promoter, to the cells transfected with deletion mutants of hIGF-Ⅱ promoter 4. HBV-X and okadaic acid both played a role in the transcriptional stimulation of human IGF-Ⅱ promoter 4. The active site(s) in HBV-X protein was also characterized through in vitro mutagenesis and deletion mutation.과기처에서 시행한 특정연구개발사업의 연구보고