Microbial regulation of DNA repair in intestinal epithelial cells

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BACKGROUND The intestine contains an abundant colony of microorganisms and intestinal epithelial cells (IEC) that are critical for regulating the interaction of these microbes with the host. IEC express numerous pattern recognition receptors (PRR) that allow them to sense and respond to microbes. This is critical since microbes can produce products that damage DNA and IEC are very susceptible to accumulating mutations because they divide frequently and must reproduce their DNA each time. While numerous protective DNA repair pathways operate within IEC, the basic question of how these repair mechanisms are regulated by intestinal microbial products remains unanswered despite the fact that the existence of such regulatory pathways could have important consequences for fundamental intestinal physiology. OBJECTIVE AND AIMS The overall objective of the proposed program is to characterize the role of intestinal microbiota in regulating DNA repair in host cells. We will accomplish this by addressing three aims. Aim 1. Determine if the activation of different PRR on IEC regulates DNA repair mechanisms. We will focus our work on the Toll-like receptors (TLR) category of PRR. We will expose IEC to microbial molecules known to activate different TLR and evaluate how this changes DNA repair protein expression and the efficiency of each DNA repair pathway. Aim 2. Determine how microbial metabolic products alter DNA repair and induce DNA damage. The byproducts of microbial metabolism exert many effects on IEC yet their influence on IEC DNA repair is unknown. We will examine the activity of different DNA repair pathways in IEC when exposed to specific microbial metabolites and determine if the IEC become more or less susceptible to the development of mutations that could alter their function. Aim 3. Determine how diet regulates microbiota-induced DNA damage in the intestine. Diet plays a significant role in determining what metabolites are produced by intestinal microbiota. However, little is known about what dietary factors regulate the generation of microbial products that directly target DNA or the efficiency of IEC DNA repair. We will use cell culture and mouse experiments to evaluate if different nutrients directly alter production of these compounds or alter the ability of microbes to regulate DNA repair. IMPACT DNA repair is a fundamental biological process that is especially important in rapidly dividing IEC. The proposed project will establish a necessary framework for future research by our team and by others since it will generate a fundamental understanding of how specific microbial species and dietary components can influence the lynchpin cell type regulating intestinal physiology. This project will also expose student trainees in my group to exciting new techniques and collaborations that will help them develop both skills and relationships that will benefit their future scientific careers.