Abstract
A critical challenge for mammalian cell engineering is the unexpected response of transgenes to native transcriptional regulation pathways. One transgene can show different levels of expression at different genomic sites, in different cell types, and under different growth conditions. Collisions between transcription and DNA replication, heterochromatin encroachment, and viral defense have been linked to transgene silencing. In this study, we identify fatty acid metabolism as another mediator of transgene behavior. Adipocyte secretome-induced lipogenesis in epithelial breast cancer cells was accompanied by the loss of expression from a Tet-TA regulated pCMV-AmCyan reporter transgene. Transcription profiling showed activation of lipid droplet biosynthesis, and repression of loci across the genome, consistent with the idea that lipogenesis affects the availability of substrates and cofactors for global chromatin remodeling. Preinduction of pCMV prevented full silencing during lipogenesis. Our results provide new insights into the influence of shifting metabolic states on transgene behavior.