Expression of Milk Protein-Cat Chimeric Genes in Transfected Bovine and Mouse Mammary Epithelial Cells

Abstract

Expression of foreign genes in mammary epithelial cells using milk protein gene promoters was investigated. About 0.5–1.0 kb of the 5′-flanking sequences of bovine αs1-, β-, κ-caseins and a-lactalbumin genes were fused to the CAT gene. The chimeric genes were transfected into a mouse mammary epithelial cell line, HC11, and primary bovine mammary epithelial cells (BMEC) by the calcium phosphate-precipitation method. The HC11 cells transfected with the casein-CAT chimeric genes showed strong CAT activity, whereas very weak or almost no activity was detected in the transfected BMEC. Expression of the casein-CAT chimeric genes in transfected HC11 cells was strongly affected by FBS concentration of the culture medium, though the effect of FBS concentration on the expression of a SV40-CAT chimeric gene was rather weak.