The integrity and function of the epithelial lining of the gastrointestinal tract, and thus human health, depend upon appropriate cellular proliferation and apoptosis, as part of the response to injury or inflammation. These processes are normally tightly regulated by an array of signaling pathways driven by cell surface receptors and their cognate ligands;aberrations in this control contribute to numerous disease states from ulceration to tumorigenesis. This project is focused on understanding the roles played by tumor necrosis factor (TNF) and its receptors (TNFR1 &TNFR2) in coordinating proliferation and apoptosis during intestinal epithelial injury and inflammation. Our studies to date have described novel mechanisms of TNFR activation and downstream signal transduction in intestinal epithelial cells, including TNF-stimulated cell survival responses such as Raf-1 regulation of nuclear factor- (NF-) :B and Src-mediated transactivation of epidermal growth factor receptor (EGFR) &ErbB2. Because these receptor systems have been linked to both pathogenesis and therapeutics, defining the mechanisms of TNFR signal transduction and the role of EGFR transactivation in the gastrointestinal tract is important to understand the clinical implications, and potential applications, of these responses. Our published results from the current funding period, combined with our Preliminary Data included in this proposal, demonstrate that TNFR1 processing, TNFR2 expression, and transactivation of EGFR/ErbB2 help to maintain an intact intestinal epithelial monolayer by reducing apoptosis and promoting proliferation. Therefore, studies described in this application will test the hypothesis that during acute injury and chronic inflammation, TNF stimulates TNFR processing and signal transduction, including transactivation of EGFR/ErbB2, to promote epithelial cell monolayer integrity and health of the host.
The Specific Aims are to: (1) Define the role of TNFR interactions and processing in intestinal epithelial cell response to injury in vitro and in vivo, (2) Determine the role of TNFR1 downstream anti-apoptotic signal transduction pathways in colon epithelium following acute and recurrent injury, and (3) Determine the effects of EGFR/ErbB2 on injury and repair mechanisms in acute and chronic inflammation in the colon. The proposed studies will significantly enhance our understanding of the roles and mechanisms of action of TNF-induced signaling on intestinal epithelial health, with implications for a number of human gastrointestinal disorders.
These studies are designed to increase the understanding of repair mechanisms of the gastrointestinal tract following injury and during inflammation. They have important relevance to the treatment and prevention of a number of human gastrointestinal disorders including inflammatory bowel disease.
|Miguel, Jennifer C; Maxwell, Adrienne A; Hsieh, Jonathan J et al. (2016) Epidermal growth factor suppresses intestinal epithelial cell shedding through a MAPK-dependent pathway. J Cell Sci :|
|Zhao, Gang; Liu, Liping; Peek Jr, Richard M et al. (2016) Activation of Epidermal Growth Factor Receptor in Macrophages Mediates Feedback Inhibition of M2 Polarization and Gastrointestinal Tumor Cell Growth. J Biol Chem 291:20462-72|
|Li, Ran; Zhang, Yufeng; Polk, D Brent et al. (2016) Preserving viability of Lactobacillus rhamnosus GG in vitro and in vivo by a new encapsulation system. J Control Release 230:79-87|
|Wang, Y; Liu, L; Moore, D J et al. (2016) An LGG-derived protein promotes IgA production through upregulation of APRIL expression in intestinal epithelial cells. Mucosal Immunol :|
|Yan, F; Liu, L; Cao, H et al. (2016) Neonatal colonization of mice with LGG promotes intestinal development and decreases susceptibility to colitis in adulthood. Mucosal Immunol :|
|Punit, Shivesh; DubÃ©, Philip E; Liu, Cambrian Y et al. (2015) Tumor Necrosis Factor Receptor 2 Restricts the Pathogenicity of CD8(+) T Cells in Mice With Colitis. Gastroenterology 149:993-1005.e2|
|Liu, Cambrian Y; DubÃ©, Philip E; Girish, Nandini et al. (2015) Optical reconstruction of murine colorectal mucosa at cellular resolution. Am J Physiol Gastrointest Liver Physiol 308:G721-35|
|DubÃ©, Philip E; Punit, Shivesh; Polk, D Brent (2015) Redeeming an old foe: protective as well as pathophysiological roles for tumor necrosis factor in inflammatory bowel disease. Am J Physiol Gastrointest Liver Physiol 308:G161-70|
|Frey, Mark R; Brent Polk, D (2014) ErbB receptors and their growth factor ligands in pediatric intestinal inflammation. Pediatr Res 75:127-32|
|Lu, Ning; Wang, Lihong; Cao, Hailong et al. (2014) Activation of the epidermal growth factor receptor in macrophages regulates cytokine production and experimental colitis. J Immunol 192:1013-23|
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