Cloning of the structural sequences of human growth hormone gene family into plasmids and its utilization in transient expression systems

Abstract

The structural sequences of human growth hormone(hGH), human chorionic somatomammotropin(hCS)-A, hCS-B genes were isolated from a partial human genomic DNA library of pBR322. The cloned genes were identified by the restriction and Southern blot hybridization analysis. A block of highly repeated sequences was contained in the 3'-flanking sequences of hGH gene but not in the hCS-A and hCS-B genes. The structural sequences of hGH gene was fused with mouse metallothionein-I(MT-I) promoter and the expression plasmid DNA was introduced into mouse L cells by transfection. hGH was transiently expressed in the transfected mouse L cells under the control of the mouse MT-I promoter. The secreted hGH in the medium was steadily accumulated during at least 10 days after transfection. When the MT-I prow' ‘er was induced by cadmium, the level of hGH was increased by several folds. Our results demonstrate that the plasmid vector containing the structural portion of the growth hormone gene can be used in transient expression systems for regulation studies.