In Vivo Characterization of Stress-Responsive Promoters in the Normal and Inflamed Murine Gastrointestinal Tract

Research in synthetic biology has led to the generation of various biological systems using specific promoter sequences for the activation of gene expression in response to particular environmental or chemical stimuli. Those systems will likely be key in the development of synthetic therapeutic organisms requiring a precise spatiotemporal control of their activation in patients suffering from the targeted medical syndromes. Thus far, however, all of the studies describing those biological systems have been performed in vitro, and additional information on their behavior in animal disease models is needed to confirm their utility for potential therapeutic applications. Using the well-known probiotic E. coli Nissle strain carrying promoter-fluorescent protein reporter constructs, we conducted the first comprehensive in vivo study of low-oxygen, oxidative stress and nitrosative stress-responsive promoters in the gastrointestinal tract of healthy mice and murine IBD (Inflammatory Bowel Disease) models. Our data are providing valuable insights into the kinetics, fine localization, and level of those promoters’ activities along the mouse GI tract and how they differ between a normal and inflamed gut. In parallel, our studies are providing important information regarding the environmental stresses synthetic therapeutic organisms would face in the context of IBD, a knowledge that will play a critical role in engineering more efficient microbial therapeutic agents.