title: Widely used enhancer of eukaryotic expression vectors is strongly and differentially regulated in fibroblast, myoblast, and teratocarcinoma cell lines.
abstract: The expression of transgenes in eukaryotic cells is a powerful approach in cell biology. In most cases, it is based on the activity of strong and constitutive viral cis-acting elements in eukaryotic expression vectors. Here we show that a widely used such element derived from an early gene of human cytomegalovirus is strongly and differentially regulated in mouse cell lines. We analyzed cytomegalovirus promoter-driven expression of stably transfected transgenes in growing, confluent, and differentiating mouse 3T3 fibroblasts, C2C12 myoblasts, and P19 teratocarcinoma cells. In the fibroblasts, transgene expression was strongly downregulated in confluent cultures and was upregulated in growing or confluent cultures by phorbol ester. In contrast, no downregulation by confluency, nor upregulation by phorbol ester, was detected in C2C12 cells. In addition, while marked upregulation was detected in differentiating myotubes, transgene expression was downregulated when differentiating teratocarcinoma cells assumed a neuronal phenotype. These results demonstrate the existence of drastic differences in the regulation of transgene expression in different types of cell lines, indicating that when studying transgene function in cells that are not growing exponentially, viral promoter-driven expression should not be taken for granted.
authors.affiliation: Friedrich Miescher Institute, Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Wiederkehr
authors.forename: P
authors.initials: P
authors.lastname: Caroni
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D003587:Cytomegalovirus / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005347:Fibroblasts / Q000821:virology; D015967:Gene Expression Regulation, Viral; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D051379:Mice; D018482:Muscle, Skeletal / Q000821:virology; D018243:Teratocarcinoma / Q000821:virology