Redox-signaling in intestinal stem cells

Conventionally, reactive oxygen species (ROS) are primarily viewed as harmful byproducts of cellular metabolism. However, it is now recognized that some ROS, particularly hydrogen peroxide (H₂O₂), play a crucial role as signaling molecules, essential for maintaining health.

These oxidative signals activate adaptive responses and guide key cell fate decisions. H₂O₂ exerts its signaling function through the reversible oxidative modification of receptors, transcription factors and other regulatory proteins. Our research focuses on understanding the molecular mechanisms that allow enzymatically generated ROS to act specifically as a signaling molecule. Specifically, ROS generated by the NADPH-oxidase 1 (NOX1), an enzyme which is highly expressed by intestinal epithelial stem cells, and responsible for maintenance of the rapid turnover of the epithelial cell layer.

We recently discovered that NOX1 contributes to stem cell proliferation via redox regulation of the EGFR receptor. Directly activating the receptor in the absence of ligand binding essential for maintaining cell proliferation in response to various signaling cues from the local environment, including from the intestinal microbiota and immune system. Our current work focuses on establishing the functional importance of redox signaling in the intestine and the dynamic regulation of NOX1 expression. Especially in relation to inflammatory bowel disease which development during early life is associated with NOX1 loss-of-function mutations, highlighting the importance of physiological levels of ROS generation for intestinal homeostasis.

To identify novel inducers of both proliferation and ROS generation we use a primary intestinal stem cell cultures from both mouse and human maintained as self-organizing organoids to screen microbial metabolite libraries. Aiding both to our basic understanding of how intestinal epithelial renewal is maintained and the contribution of ROS generation. We envision that these findings will contribute to the development of innovative strategies using microbial metabolites for supplementary treatment of diseases where the intestinal barrier is compromised such as in inflammatory bowel disease. In addition, we aim to delineate the NOX1-dependent redox regulated proteins and pathways that promote colonic epithelial stem cells proliferation. We do this by studying the extend of cysteine oxidation using novel mass spectrometry methods which enables us to determine the modification status on thousands of proteins in parallel. The analysis of these datasets is a challenge, for which we develop analysis tools in parallel to get a functional understanding of modified cysteine residues in the molecular architecture of the proteins structure.