title: Lack of glucagon receptor signaling and its implications beyond glucose homeostasis.
abstract: Glucagon action is transduced by a G protein-coupled receptor located in liver, kidney, intestinal smooth muscle, brain, adipose tissue, heart, pancreatic β-cells, and placenta. Genetically modified animal models have provided important clues about the role of glucagon and its receptor (Gcgr) beyond glucose control. The PubMed database was searched for articles published between 1995 and 2014 using the key terms glucagon, glucagon receptor, signaling, and animal models. Lack of Gcgr signaling has been associated with: i) hypoglycemic pregnancies, altered placentation, poor fetal growth, and increased fetal-neonatal death; ii) pancreatic glucagon cell hyperplasia and hyperglucagonemia; iii) altered body composition, energy state, and protection from diet-induced obesity; iv) impaired hepatocyte survival; v) altered glucose, lipid, and hormonal milieu; vi) altered metabolic response to prolonged fasting and exercise; vii) reduced gastric emptying and increased intestinal length; viii) altered retinal function; and ix) prevention of the development of diabetes in insulin-deficient mice. Similar phenotypic findings were observed in the hepatocyte-specific deletion of Gcgr. Glucagon action has been involved in the modulation of sweet taste responsiveness, inotropic and chronotropic effects in the heart, satiety, glomerular filtration rate, secretion of insulin, cortisol, ghrelin, GH, glucagon, and somatostatin, and hypothalamic signaling to suppress hepatic glucose production. Glucagon (α) cells under certain conditions can transdifferentiate into insulin (β) cells. These findings suggest that glucagon signaling plays an important role in multiple organs. Thus, treatment options designed to block Gcgr activation in diabetics may have implications beyond glucose homeostasis.
authors.affiliation: Departments of BiochemistryObstetrics and Gynecology and Women's HealthMedicineAlbert Einstein College of Medicine, 1300 Morris Park Avenue, F312, Bronx, New York 10461, USADepartment of PediatricsHofstra School of Medicine, Cohen Children's Medical Center, 1991 Marcus Avenue, Lake Success, New York 11402, USA Departments of BiochemistryObstetrics and Gynecology and Women's HealthMedicineAlbert Einstein College of Medicine, 1300 Morris Park Avenue, F312, Bronx, New York 10461, USADepartment of PediatricsHofstra School of Medicine, Cohen Children's Medical Center, 1991 Marcus Avenue, Lake Success, New York 11402, USA Departments of BiochemistryObstetrics and Gynecology and Women's HealthMedicineAlbert Einstein College of Medicine, 1300 Morris Park Avenue, F312, Bronx, New York 10461, USADepartment of PediatricsHofstra School of Medicine, Cohen Children's Medical Center, 1991 Marcus Avenue, Lake Success, New York 11402, USA pvuguin@nshs.edu maureen.charron@einstein.yu.edu.
authors.forename: Maureen J
authors.initials: MJ
authors.lastname: Charron
authors.affiliation: Departments of BiochemistryObstetrics and Gynecology and Women's HealthMedicineAlbert Einstein College of Medicine, 1300 Morris Park Avenue, F312, Bronx, New York 10461, USADepartment of PediatricsHofstra School of Medicine, Cohen Children's Medical Center, 1991 Marcus Avenue, Lake Success, New York 11402, USA pvuguin@nshs.edu maureen.charron@einstein.yu.edu.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Vuguin
mesh_terms: D000818:Animals; D005260:Female; D047109:Fetal Development / Q000235:genetics; D005934:Glucagon / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis / Q000235:genetics*; D006801:Humans; D051379:Mice; D023421:Models, Animal; D010179:Pancreas / Q000166:cytology / Q000196:embryology; D011247:Pregnancy; D011255:Pregnancy Maintenance / Q000235:genetics; D018027:Receptors, Glucagon / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D018027:Receptors, Glucagon; D005934:Glucagon; D005947:Glucose
keywords: glucagon cells; pancreas