| First Author | Bozadjieva Kramer N | Year | 2021 |
| Journal | Diabetes | Volume | 70 |
| Issue | 2 | Pages | 477-491 |
| PubMed ID | 33239450 | Mgi Jnum | J:307110 |
| Mgi Id | MGI:6712890 | Doi | 10.2337/db20-0440 |
| Citation | Bozadjieva Kramer N, et al. (2021) Glucagon Resistance and Decreased Susceptibility to Diabetes in a Model of Chronic Hyperglucagonemia. Diabetes 70(2):477-491 |
| abstractText | Elevation of glucagon levels and increase in alpha-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 alpha-cell mass. In the current studies we investigated the effects of activation of nutrient signaling by conditional deletion of the mTORC1 inhibitor, TSC2, in alpha-cells (alphaTSC2(KO)). We showed that activation of mTORC1 signaling is sufficient to induce chronic hyperglucagonemia as a result of alpha-cell proliferation, cell size, and mass expansion. Hyperglucagonemia in alphaTSC2(KO) 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 alphaTSC2(KO) 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 alphaTSC2(KO) mice was associated with improved glucose levels in streptozotocin-induced beta-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. |
