Fully Human Monoclonal Antibodies Antagonizing the Glucagon Receptor Improve Glucose Homeostasis in Mice and Monkeys

Yan, Hai; Gu, Wei; Yang, Jie; Bi, Vivian; Shen, Yuqing; Lee, Eunkyung; Winters, Katherine A.; Komorowski, Renée; Zhang, Cheng; Patel, Jennifer; Caughey, Dorothy; Elliott, Gary; Lau, Yvonne; Wang, Jin; Li, Yuesheng; Boone, T.; Lindberg, Richard A.; Hu, Sylvia; Véniant, Murielle M.

doi:10.1124/jpet.108.147009

Cited by 115 publications

(112 citation statements)

References 41 publications

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“…S1A). The binding and inhibitory characteristics of two of the most potent antibodies, mAb7 and mAb23, were compared with a recently described inhibitory antibody that improves glycemic control in animal models of diabetes (7,8), herein termed mAb1. All three antibodies inhibited glucagon-induced gene expression in primary human hepatocytes (Fig.…”

Section: Antagonist and Inverse Agonist Antibodies Targeting The Gcgrmentioning

confidence: 99%

“…Several GCGR antagonists that improve glycemic control in animal models of diabetes and diabetic patients have been described (3)(4)(5)(6)(7)(8). Although biochemical studies of glucagon and GCGR mutants have facilitated the mapping of some elements that contribute to glucagon binding (4,(9)(10)(11)(12), the molecular mechanisms of GCGR activation and inhibition remain largely unknown because there are currently no high-resolution structures of GCGR.…”

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confidence: 99%

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Molecular basis for negative regulation of the glucagon receptor

Koth¹,

Murray²,

Mukund³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

123

179

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Members of the class B family of G protein-coupled receptors (GPCRs) bind peptide hormones and have causal roles in many diseases, ranging from diabetes and osteoporosis to anxiety. Although peptide, small-molecule, and antibody inhibitors of these GPCRs have been identified, structure-based descriptions of receptor antagonism are scarce. Here we report the mechanisms of glucagon receptor inhibition by blocking antibodies targeting the receptor's extracellular domain (ECD). These studies uncovered a role for the ECD as an intrinsic negative regulator of receptor activity. The crystal structure of the ECD in complex with the Fab fragment of one antibody, mAb1, reveals that this antibody inhibits glucagon receptor by occluding a surface extending across the entire hormone-binding cleft. A second antibody, mAb23, blocks glucagon binding and inhibits basal receptor activity, indicating that it is an inverse agonist and that the ECD can negatively regulate receptor activity independent of ligand binding. Biochemical analyses of receptor mutants in the context of a high-resolution ECD structure show that this previously unrecognized inhibitory activity of the ECD involves an interaction with the third extracellular loop of the receptor and suggest that glucagon-mediated structural changes in the ECD accompany receptor activation. These studies have implications for the design of drugs to treat class B GPCR-related diseases, including the potential for developing novel allosteric regulators that target the ECDs of these receptors.T he glucagon receptor (GCGR) is a member of the class B G protein-coupled receptor (GPCR) family (1) that mediates the activity of glucagon, a pancreatic islet-derived peptide hormone that plays a central role in the pathophysiology of diabetes (2). Several GCGR antagonists that improve glycemic control in animal models of diabetes and diabetic patients have been described (3-8). Although biochemical studies of glucagon and GCGR mutants have facilitated the mapping of some elements that contribute to glucagon binding (4, 9-12), the molecular mechanisms of GCGR activation and inhibition remain largely unknown because there are currently no high-resolution structures of GCGR. The current model for activation class B GPCRs proposes a tethering mechanism whereby the C-terminal half of the peptide ligand first binds a large extracellular domain (ECD), thereby enabling a high-affinity interaction of the N-terminal half of the ligand with a cleft formed by the transmembrane α-helical bundle (13,14), termed the juxtamembrane (JM) domain. This interaction induces a structural change in the transmembrane and intracellular face of the receptor that enables G protein coupling, likely similar to that described for the activated form of the β-adrenergic receptor (15). Recent structural studies of several class B GPCR ECDs and ECD-ligand complexes support this model (16)(17)(18)(19)(20)(21). Glucagon likely interacts with GCGR in a similar fashion to the interaction of other peptide ligands with class B GPC...

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Section: Antagonist and Inverse Agonist Antibodies Targeting The Gcgrmentioning

confidence: 99%

mentioning

confidence: 99%

Molecular basis for negative regulation of the glucagon receptor

Koth¹,

Murray²,

Mukund³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

123

179

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“…Consistently, the inhibition of GCGR by ASOs significantly reduced the circulating levels of triacylgycerol, NEFA and glucose in db/db mice [13]. Furthermore, the use of GCGR neutralising antibody improved glycaemic control in obese or diabetic mouse models [14,15].…”

Section: Introductionmentioning

confidence: 63%

“…Given the much greater muscle mass compared with that of liver and kidneys, the ectopic production of GCGR in the muscle thus provides effective 'decoy receptors'. However, unlike the robust hyperglucagonaemia observed in the Gcgr −/− mice [10] or the mice receiving therapeutic intervention by GCGR antagonistic strategies [13,15], Mck/Gcgr mice displayed a relatively mild increase in glucagon levels. Furthermore, elevated glucagon levels were associated with increased insulin levels in Mck/Gcgr mice, allowing the maintenance of an appropriate glucagonto-insulin ratio, which is critical in maintaining glycaemic stability, particularly in extremes of glucose influx or efflux [6,30].…”

Section: Discussionmentioning

confidence: 82%

Ectopic expression of glucagon receptor in skeletal muscles improves glucose homeostasis in a mouse model of diabetes

et al. 2012

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Aims/hypothesis Excessive secretion of glucagon partially contributes to the development of diabetic hyperglycaemia. However, complete blocking of glucagon action will lead to adverse effects, since glucagon exerts certain beneficial effects via its receptor in many organs. We aimed to study the effects of a 'decoy receptor' for circulating glucagon on modulating beta cell function and glucose homeostasis in mice by over-producing the glucagon receptor (GCGR) in skeletal muscles. Methods We generated transgenic mice in which the expression of Gcgr is driven by the muscle specific creatine kinase (Mck) promoter, and assessed the effects of glucagon on the modulation of glucose homeostasis under conditions of extremes of glucose influx or efflux.Results Mck/Gcgr mice showed increased circulating levels of glucagon and insulin, resulting in an unchanged ratio of glucagon-to-insulin. The levels of hepatic glucose-6-phosphatase (G6PC) and fructose-1,6-bisphosphatase (F1,6P2ase) were significantly decreased, whereas the phosphorylation level of pancreatic cAMP-response-element-binding-protein (CREB) was significantly increased in these transgenic mice. Under basal conditions, the mice displayed normal blood glucose levels and unchanged glucose tolerance and insulin sensitivity when compared with their age-matched wild-type (WT) littermates. However, following multiple lowdose streptozotocin injections, Mck/Gcgr mice exhibited a delay in the onset of hyperglycaemia compared with the WT controls. This was associated with preserved beta cell mass and beta cell secretory capacity in response to glucose challenge.A. Maharaj and L. Zhu contributed equally to this study. Electronic supplementary material The online version of this article

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“…It was originally shown by Peter Flatt in 1979 that administration of glucagon antibodies modulated glucose levels 56 -another first for a student -and more recently administration of glucagon receptor blocking antibodies to nondiabetic monkeys reduced blood glucose level in a dose dependent manner. 57 The antibody was also given in higher doses to ob/ob mice and was successful in suppressing their hyperglycaemia. 58 Early clinical trials in patients with type 2 diabetes mellitus show promise.…”

Section: Novel Drugs That Target the Glucagon Pathway And Alpha Cell mentioning

confidence: 99%

Alpha cell function in type 1 diabetes

Hughes

Narendran

2014

Br J Diabetes

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Our understanding of the pathogenesis of type 1 diabetes mellitus has traditionally revolved around the insulin deficiency that follows pancreatic beta cell loss. However, there is an increasing appreciation of defects in other glucoregulatory cells in type 1 diabetes mellitus. Oversecretion of glucagon from pancreatic alpha cells is characteristic of type 1 diabetes mellitus, and modulating these glucagon levels reduces hyperglycaemia. This article reviews alpha cell function in type 1 diabetes mellitus. We examine how its function is controlled and compromised, and review studies that target alpha cell function. Finally, we explore potential approaches to modulating alpha cell function in type 1 diabetes mellitus. Br J Diabetes Vasc Dis 2014;14:45-51

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Fully Human Monoclonal Antibodies Antagonizing the Glucagon Receptor Improve Glucose Homeostasis in Mice and Monkeys

Cited by 115 publications

References 41 publications

Molecular basis for negative regulation of the glucagon receptor

Molecular basis for negative regulation of the glucagon receptor

Ectopic expression of glucagon receptor in skeletal muscles improves glucose homeostasis in a mouse model of diabetes

Alpha cell function in type 1 diabetes

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