Molecular Approaches to Influence Epigenetic Effectors of Transient and Stable Transgene Expression in Mammalian Cells

Abstract

Transient and stable transgene expression in mammalian cells is influenced by epigenetic factors such as histone modifications and DNA methylation. Here we demonstrate the feasibility of using molecular approaches to overcome the potentially negative effects of these factors. Chinese hamster ovary cells (CHO) were co-transfected with the CELO adenovirus Gam1 gene and either the enhanced green fluorescent protein (EGFP) gene or the IgG heavy and light chain genes. In both cases the expression of the reporter protein was increased in the presence of Gam1. Transient expression of Gam1 in YIGG2 cells, a stable CHO cell line that carries a silenced enhanced yellow fluorescent protein (EYFP) gene, resulted in higher expression of this reporter protein. Lastly, targeting of the adenovirus E1A mRNA in HEK293 cells for degradation by RNAi resulted in a two-fold increase in the transient expression of a co-transfected reporter gene. These results demonstrate that epigenetic factors do play a role in stable and transient transgene expression and that molecular approaches can be developed to relieve the negative effects of these factors on recombinant protein expression in mammalian cells.