Liver-specific disruption of the murine glucagon receptor produces α-cell hyperplasia: evidence for a circulating α-cell growth factor.

Longuet C, Robledo AM, Dean ED, Dai C, Ali S, McGuinness I, de Chavez V, Vuguin PM, Charron MJ, Powers AC, Drucker DJ
Diabetes. 2013 62 (4): 1196-205

PMID: 23160527 · PMCID: PMC3609565 · DOI:10.2337/db11-1605

Glucagon is a critical regulator of glucose homeostasis; however, mechanisms regulating glucagon action and α-cell function and number are incompletely understood. To elucidate the role of the hepatic glucagon receptor (Gcgr) in glucagon action, we generated mice with hepatocyte-specific deletion of the glucagon receptor. Gcgr(Hep)(-/-) mice exhibited reductions in fasting blood glucose and improvements in insulin sensitivity and glucose tolerance compared with wild-type controls, similar in magnitude to changes observed in Gcgr(-/-) mice. Despite preservation of islet Gcgr signaling, Gcgr(Hep)(-/-) mice developed hyperglucagonemia and α-cell hyperplasia. To investigate mechanisms by which signaling through the Gcgr regulates α-cell mass, wild-type islets were transplanted into Gcgr(-/-) or Gcgr(Hep)(-/-) mice. Wild-type islets beneath the renal capsule of Gcgr(-/-) or Gcgr(Hep)(-/-) mice exhibited an increased rate of α-cell proliferation and expansion of α-cell area, consistent with changes exhibited by endogenous α-cells in Gcgr(-/-) and Gcgr(Hep)(-/-) pancreata. These results suggest that a circulating factor generated after disruption of hepatic Gcgr signaling can increase α-cell proliferation independent of direct pancreatic input. Identification of novel factors regulating α-cell proliferation and mass may facilitate the generation and expansion of α-cells for transdifferentiation into β-cells and the treatment of diabetes.

MeSH Terms (18)

Animals Blood Glucose Female Glucagon Glucagon-Secreting Cells Glucose Hepatocytes Hyperplasia Insulin Resistance Intercellular Signaling Peptides and Proteins Islets of Langerhans Liver Male Mice Mice, Inbred C57BL Mice, Knockout Receptors, Glucagon Signal Transduction

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