Development and Application of Metabolomics Techniques to Improve Understanding of Glucose and Fatty Acid Metabolism in ß-cells and their Role in Insulin Secretion.

Metabolomics;Glucose Stimulated Insulin Secretion;Chemistry;Science;Chemistry

El Azzouny, MahmoudHakansson, Kristina I. ;

University of Michigan

关键词: Metabolomics;    Glucose Stimulated Insulin Secretion;    Chemistry;    Science;    Chemistry;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107168/mazzouny_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The primary function of pancreatic beta cells is to secrete insulin in response to glucose metabolism.Decline in beta cell function contributes to the development of type 2 diabetes (T2D). Diabetic patients suffer from low levels of insulin and high levels of glucose and fatty acid in their blood.However, in pre-diabetes, before the decline in beta cell function and the development of T2D has occurred, beta cells secrete higher levels of insulin in blood.The mechanism of insulin secretion and hyperinsulemia are not yet fully understood. Metabolomics, a method first described in 1998, is a modern tool devised to monitor the dynamics of metabolites in biological samples. This technique provides valuable information which may aid understanding of how beta cells secrete insulin in response to different nutrients.This dissertation is focused on the use of metabolomics techniques to study insulin secretion in a beta cell line (INS-1 cells). We developed and optimized an analytical platform that allowed us to monitor glucose and fatty acid metabolism inside beta cells. We used stable-isotope labeled metabolic tracers that enabled us to probe nutrient flux in several pathways involved in insulin secretion.Using the developed platform we were able to better understand the mechanism(s) by which glucose can stimulate insulin secretion. Important pathways involved in insulin secretion were probed using labeled glucose and pharmacological agents.We applied metabolomics to understand why acute exposure to high fatty acid and glucose lead to the potentiation of insulin secretion. We showed that in beta cells, fatty acids increase glucose oxidation, while themselves being minimally oxidized. Using pharmacological agents and siRNA techniques, we showed a novel role for the free fatty acid receptor (FFAR1/GPR40) in controlling fatty acid and glucose metabolism.Finally, we tried to understand the mechanism of action of a new pharmacological agent (AICAR), which mimics starvation conditions within a cell.We showed that AMPK activation by AICAR treatment lead to beneficial effects on beta cells by reducing lipid mediators that are known to reduce apoptosis. However, as AICAR is a purine analog, we showed that it blocked pathways involved in nucleic acid synthesis.