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Glucagon Resistance and Decreased Susceptibility to Diabetes in a Model of Chronic Hyperglucagonemia.

Citation
Kramer, N. B., et al. “Glucagon Resistance And Decreased Susceptibility To Diabetes In A Model Of Chronic Hyperglucagonemia.”. Diabetes, pp. 477-491.
Center University of Michigan
Author Nadejda Bozadjieva Kramer, Camila Lubaczeuski, Manuel Blandino-Rosano, Grant Barker, George K Gittes, Alejandro Caicedo, Ernesto Bernal-Mizrachi
Abstract

Elevation of glucagon levels and increase in α-cell mass are associated with states of hyperglycemia in diabetes. Our previous studies have highlighted the role of nutrient signaling via mTOR complex 1 (mTORC1) regulation that controls glucagon secretion and α-cell mass. In the current studies we investigated the effects of activation of nutrient signaling by conditional deletion of the mTORC1 inhibitor, TSC2, in α-cells (αTSC2). We showed that activation of mTORC1 signaling is sufficient to induce chronic hyperglucagonemia as a result of α-cell proliferation, cell size, and mass expansion. Hyperglucagonemia in αTSC2 was associated with an increase in glucagon content and enhanced glucagon secretion. This model allowed us to identify the effects of chronic hyperglucagonemia on glucose homeostasis by inducing insulin secretion and resistance to glucagon in the liver. Liver glucagon resistance in αTSC2 mice was characterized by reduced expression of the glucagon receptor (GCGR), PEPCK, and genes involved in amino acid metabolism and urea production. Glucagon resistance in αTSC2 mice was associated with improved glucose levels in streptozotocin-induced β-cell destruction and high-fat diet-induced glucose intolerance. These studies demonstrate that chronic hyperglucagonemia can improve glucose homeostasis by inducing glucagon resistance in the liver.

Year of Publication
2021
Journal
Diabetes
Volume
70
Issue
2
Number of Pages
477-491
Date Published
02/2021
ISSN Number
1939-327X
DOI
10.2337/db20-0440
Alternate Journal
Diabetes
PMID
33239450
PMCID
PMC7881862
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