Sustained Heterologous Transgene Expression in Mammalian and Avian Cell Lines

Chromosomal position effects are the cause of variegation of transgene expression relating to the eukaryotic genome environment. These effects modify heterologous transgene expression, presumably due to dominant epigenetic marks that cause variegated or gradual silencing of transgene expression. As a solution, chromosomal insulators have arisen as a way to protect transgene expression against repressive marks (position effects), allowing homogeneous and consistent expression. Sustainable expression enables us to gain insight into in vivo protein function and protein stability, or to study position effects. Here, we show that the chicken cHS4 beta-globin insulator is able to protect transgene expression in cell lines, demonstrating its potential as a tool to improve the heterologous expression of any desired transgene. In addition, we show that green fluorescent protein (GFP) can be used as a reporter protein in the study of chromosomal position effects.