Orthogonal control of mean and variability of endogenous genes in a human cell line

Abstract Stochastic fluctuations at the transcriptional level contribute to isogenic cell-to-cell heterogeneity in mammalian cell populations. However, we still have no clear understanding of repercussions this heterogeneity, given lack tools independently control mean expression and variability a gene. Here, engineer synthetic circuit modulate transgenes endogenous human genes. The circuit, Tunable Noise Rheostat (TuNR), consists cascade two inducible activators, where output variance can be modulated by orthogonal small molecule inputs. In fashion, different combinations inputs achieve same but with population variability. With TuNR, low basal expression, over 1000-fold transgene product, up 7-fold induction gene NGFR . Importantly, for level, are able establish varying degrees within an population, thereby decoupling noise from its mean. TuNR is therefore modular tool that used cells enable direct interrogation implications