New insights from our studies and others indicate that the gastric mucosa may sense overall energy balance and control metabolic rate through fine-tuning the production of two counteracting hormones: ghrelin and nesfatin-1, in X/A like cells. Ghrelin, a 28-amino acid gastric peptide hormone, was originally identified as an orexigenic factor, and is the only known circulating hormone able to initiate food intake. X/A like cells has been discovered to also secrete the anorexigenic hormone nesfatin-1. Our data indicate that the balance of ghrelin and nesfatin-1 secretion regulates nutrient intake. Our studies also indicate that the mechanistic target of rapamycin (mTOR) signaling pathway in the gastric mucosa plays a critical role in the coordination of nutrient availability, ingestive behavior and metabolic activity. Based on these observations, we hypothesize that mTOR signaling regulates fuel sensing via gastric X/A like endocrine cells. This signaling pathway coordinates overall energy balance by differential regulation of the orexigenic hormone ghrelin and the anorexigenic hormone nesfatin-1. We propose 3 specific aims to investigate the function of the gastric mTOR pathway in the production of these peptides and thus their effects on appetite control and energy expenditure.
Aim 1 is designed to test the hypothesis that organismal fuel status affects phosphorylation of mTOR in gastric X/A like cells, and that mTOR signaling differentially regulates ghrelin and nesfatin-1 production.
Aim 2 will first examine the alternative AMPK-HDAC5-mTOR signaling pathway in the regulation of ghrelin and nesfatin-1. We will then test the hypothesis that S6K1 and 4EBP1 are mTOR downstream molecules regulating the reciprocal translation of ghrelin and nesfatin-1.
Aim 3 will demonstrate that gastric mTOR signaling affects food intake, energy expenditure and body weight in mice vial acyl-ghrelin and nesfatin-1. Completion of this proposal will advance our understanding of the interaction between gastric X/A like cells and nutrient intake. These findings suggest a completely new therapeutic approach directed at gastric sites.

Public Health Relevance

The gastric hormones ghrelin and nesfatin-1 are important for the regulation of food intake and energy balance. This proposal will investigate the function of the mechanistic target of rapamycin in affecting ghrelin and nesfatin-1 production and appetite control. The information generated from this project will provide new insights relevant to treatment strategies for obesity and its related metabolic diseases such as diabetes and fatty liver.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Gastrointestinal Mucosal Pathobiology Study Section (GMPB)
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Maruvada, Padma
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University of Michigan Ann Arbor
Schools of Medicine
Ann Arbor
United States
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He, Rui; Yin, Yue; Yin, Wenzhen et al. (2018) Prevention of pancreatic acinar cell carcinoma by Roux-en-Y Gastric Bypass Surgery. Nat Commun 9:4183