Transcriptional regulation of mitochondrial metabolism in human intestinal stem cells

PROJECT SUMMARY Dr. Joseph Burclaff, PhD is mentored by Dr. Scott Magness, PhD at the University of North Carolina at Chapel Hill. UNC receives the 6th highest federal research funding of any American university and is home to the NIDDK-sponsored Center for Gastrointestinal Biology and Disease with a vibrant research community. The CGIBD and Dr. Burclaff’s home department of Biomedical Engineering provide supportive environments for young investigators. Dr. Burclaff proposes an innovative cross-disciplinary research plan bridging human in vitro genetic engineering, in vivo mouse work, functional metabolic studies, inflammatory signals, and transcription factor analysis, all within the frameworks of homeostasis and inflammatory bowel disease (IBD). Dynamic regulation of mitochondrial metabolism is essential for healthy intestinal stem cell (ISC) activity, with mitochondrial dysfunction known to drive inflammatory signaling and aberrant cell fates able to initiate experimental colitis. IBD is marked by decreased mitochondria, increased proinflammatory signaling, and altered ISC cycling, and mitochondrial and pro-inflammatory signaling are even seen in non-inflamed tissue from IBD patients, implicating mitochondrial dysfunction as an early event in IBD development or even predisposing the intestinal epithelium for inflammation. Few transcription factors (TFs) are known to regulate mitochondrial dynamics in ISCs. My work with primary human ISCs genetically engineered to knockout or induce overexpression of the TF SOX9 show that SOX9 strongly represses mitochondrial activity, slows cell cycle, and increases proinflammatory gene expression in ISCs. The specific effects of SOX9 on mitochondria and whether SOX9 regulates inflammatory signaling and ISC activity directly or by acting through mitochondria are unknown. This proposal will determine how SOX9 regulates mitochondria and proinflammatory signaling in human ISCs and in mice. As SOX9 often acts through other TFs, and SOX9 appears to regulate mitochondria without affecting previously implicated mitochondrial-related TFs in these ISCs, candidate TFs identified using this primary human intestinal platform will be tested for their ability to regulate mitochondria and ISC activity independently or as a TF network. Cutting-edge cellular engineering strategies will further test direct downstream targets of these TFs to determine mechanisms by which this novel network regulates mitochondria in the human intestinal epithelium. To establish an independent research area in this field, Dr. Burclaff requires mentored time to become fluent in metabolism and metabolomics, TF interactions with each other and downstream genomic targets, and IBD development. To achieve this, Dr. Burclaff will be co-mentored by Dr. Costas Lyssiotis at the University of Michigan, a field expert in metabolism and metabolomic analysis in gastrointestinal tissues and disease states. Dr. Burclaff also assembled a committee of field experts in metabolism, chromatin and TF analysis, and IBD to help guide him through this project and in his transition to establish an independent research program to train the next generation of researchers and to study regulatory mechanisms of ISCs that affect human health.