Glucagon receptor agonism and treatment withdrawal effect on liver transcriptomes of diet-induced obese mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE269328 | GEO | 2025/12/30
REPOSITORIES: GEO
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Project description:Glucagon, an essential regulator of glucose and lipid metabolism, also promotes weight loss, in part through potentiation of fibroblast-growth factor 21 (FGF21) secretion. However, FGF21 is only a partial mediator of metabolic actions ensuing from GcgR-activation, prompting us to search for additional pathways. Intriguingly, chronic GcgR agonism increases plasma bile acid levels. We hypothesized that GcgR agonism regulates energy metabolism, at least in part, through farnesoid X receptor (FXR). To test this hypothesis, we studied whole body and liver-specific FXR knockout (FXR∆liver) mice. Chronic GcgR agonist (IUB288) administration in diet-induced obese (DIO) Gcgr, Fgf21 and Fxr whole body or liver-specific knockout (∆liver) mice failed to reduce body weight (BW) when compared to wildtype (WT) mice. IUB288 increased energy expenditure and respiration in DIO WT mice, but not FXR∆liver mice. GcgR agonism increased [14C]-palmitate oxidation in hepatocytes isolated from WT mice in a dose-dependent manner, an effect blunted in hepatocytes from FXR∆liver mice. Our data clearly demonstrate that control of whole body energy expenditure by GcgR agonism requires intact FXR signaling in the liver. This heretofore-unappreciated aspect of glucagon biology has implications for the use of GcgR agonism in the therapy of metabolic disorders.
2019-08-16 | GSE135881 | GEO
Project description:Glucagon and glucagon-like peptide-1 (GLP-1) are hormones involved in energy homeostasis. GLP-1 receptor (GLP-1R) agonism reduces food intake and delays gastric emptying, and glucagon receptor (GCGR) agonism increases energy expenditure by thermogenesis. BI 456906 is a subcutaneous, once-weekly injectable dual GLP-1R/GCGR agonist in development for the treatment of obesity or non-alcoholic steatohepatitis. Here we show that BI 456906 is a potent dual agonist with an extended half-life in human plasma. Key GLP-1R-mediated mechanisms of reduced food intake, delayed gastric emptying and improved glucose tolerance were confirmed in GLP-1R knockout mice. GCGR activity was confirmed by reduced plasma amino acids, increased hepatic expression of nicotinamide N-methyltransferase and increased energy expenditure. BI 456906 produced greater bodyweight reductions than maximally efficacious semaglutide doses and modulated gene expression, including genes involved in amino acid metabolism. BI 456906 is a potent dual agonist that produces bodyweight-lowering effects through both GLP-1R and GCGR agonism.
2022-12-09 | GSE211105 | GEO
Project description:Early drivers of Type 2 diabetes mellitus (T2D) include ectopic fat accumulation, especially in the liver, that significantly impairs insulin sensitivity. In a T2D setting, GLP-1R/GCGR dual agonists have been shown to reduce glycaemia, body weight and hepatic steatosis. We utilized cotadutide, a well characterized GLP-1R/GCGR dual-agonist, to demonstrate improved insulin sensitivity during hyperinsulinemic euglycemic clamp following sub-chronic dosing in male, diet-induced obese mice. Cotadutide or GCGR monoagonist treatment resulted in specific increased brown adipose tissue (BAT) insulin-stimulated glucose uptake, while GLP-1R monoagonist only showed a weak effect. BAT from cotadutide treated mice had induction of UCP-1 protein, increased mitochondrial area and a transcriptomic profile of increased fat oxidation and mitochondrial activity. Thus, GLP-1R/GCGR dual agonism provides multimodal efficacy to decrease hepatic steatosis and consequently improve insulin sensitivity, in concert with recovery of endogenous β-cell function and reduced insulin demand. This substantiates GLP-1R/GCGR dual-agonism as a novel and effective T2D treatment.
2025-03-06 | GSE284233 | GEO
Project description:Early drivers of Type 2 diabetes mellitus (T2D) include ectopic fat accumulation, especially in the liver, that significantly impairs insulin sensitivity. In a T2D setting, GLP-1R/GCGR dual agonists have been shown to reduce glycaemia, body weight and hepatic steatosis. We utilized cotadutide, a well characterized GLP-1R/GCGR dual-agonist, to demonstrate improved insulin sensitivity during hyperinsulinemic euglycemic clamp following sub-chronic dosing in male, diet-induced obese mice. Phosphoproteomic analyses of insulin stimulated liver from cotadutide treated diet-induced obese (DIO) mice identified novel phosphorylation sites on key insulin signalling pathway proteins associated with improved insulin sensitivity. Cotadutide or GCGR monoagonist treatment also resulted in specific increased brown adipose tissue (BAT) insulin-stimulated glucose uptake, while GLP-1R monoagonist only showed a weak effect. BAT from cotadutide treated mice had induction of UCP-1 protein, increased mitochondrial area and a transcriptomic profile of increased fat oxidation and mitochondrial activity. Finally, the cotadutide-induced improvement in insulin sensitivity was associated with reduced insulin secretion from isolated pancreatic islet β-cells indicating reduced insulin secretory demand. Thus, GLP-1R/GCGR dual agonism provides multimodal efficacy to decrease hepatic steatosis and consequently improve insulin sensitivity, in concert with recovery of endogenous β-cell function and reduced insulin demand. This substantiates GLP-1R/GCGR dual-agonism as a novel and effective T2D treatment
2025-03-28 | PXD057744 | Pride
Project description:Tirzepatide, a glucose-dependent insulinotropic polypeptide/glucagon-like peptide 1 receptor (GIPR/GLP-1R) agonist, has, in clinical trials, demonstrated greater reductions in glucose, body weight and triglyceride levels compared with selective GLP-1R agonists in people with type 2 diabetes (T2D). However, cellular mechanisms by which GIPR agonism may contribute to these improved efficacy outcomes have not been fully defined. Using human adipocyte and mouse models, we investigated how long-acting GIPR agonists regulate fasted and fed adipocyte functions in the presence and absence of insulin to model post-prandial and post-absorptive states. Transcriptional profiling of human adipocytes demonstrated differential gene, pathway, and upstream regulation by GIP indicative of modulation of both carbohydrate and lipid metabolism. In functional assays, GIPR agonism enhanced insulin signaling, augmented glucose uptake, and increased the conversion of glucose to glycerol in a cooperative manner with insulin. GIPR agonists increased lipolysis in the absence of insulin, an effect that was fully suppressed when co-administered with insulin. In diet-induced obese mice treated with a long-acting GIPR agonist, circulating triglyceride levels were reduced during oral lipid challenge and lipoprotein-derived fatty acid uptake into adipose tissue was increased. Our findings support a model for long-acting GIPR agonists to modulate both fasted and fed adipose tissue function differentially, by cooperating with insulin to augment glucose and lipid clearance in the fed state, while enhancing lipid release when insulin levels are reduced in the fasted state. This novel paradigm illustrates key mechanisms by which GIPR/GLP-1R agonists such as tirzepatide likely regulate adipocyte function to enhance weight loss as well as improve glucose and lipid metabolism in T2D.
2025-03-28 | GSE262677 | GEO
Project description:Glucagon and insulin are counter-regulatory pancreatic hormones that precisely control blood glucose homeostasis1. Type 2 diabetes mellitus (T2DM) is characterized by inappropriately elevated blood glucagon2-5 levels as well as insufficient glucose stimulated insulin secretion (GSIS) by pancreatic ß-cells6. Early in the pathogenesis of T2DM, hyperglucagonemia is observable antecedent to ß-cell dysfunction7-9; and in mice, liver-specific activation of glucagon receptor-dependent signaling results in impaired GSIS10. However, the mechanistic relationship between hyperglucagonemia, hepatic glucagon action, and ß-cell dysfunction remains poorly understood. Here we show that glucagon action stimulates hepatic production of the neuropeptide kisspeptin1, which acts in an endocrine manner on ß-cells to suppress GSIS. In vivo glucagon administration acutely stimulates hepatic kisspeptin1 production, and kisspeptin1 is increased in livers from humans with T2DM and from mouse models of diabetes mellitus. Synthetic kisspeptin1 potently suppresses GSIS in vivo and in vitro from normal isolated islets, which express the kisspeptin1 receptor Kiss1R. Administration of a Kiss1R antagonist in diabetic Leprdb/db mice potently augments GSIS and reduces glycemia. Our observations indicate in the pathogenesis of T2DM an endocrine mechanism sequentially linking hyperglucagonemia via hepatic kisspeptin1 production to impaired insulin secretion. In addition, our findings suggest Kiss1R antagonism as a therapeutic avenue to improve ß-cell function in T2DM. Total RNA from L-Δprkar1a KO mice compared to control D-glucose mice
2014-04-01 | E-GEOD-48815 | biostudies-arrayexpress
Project description:In the setting of obesity and insulin resistance, glycemia is controlled in part by beta cell compensation and subsequent hyperinsulinemia. Weight loss improves glycemia and decreases hyperinsulinemia, whereas weight cycling worsens glycemic control. The mechanisms responsible for weight cycling-induced deterioration in glucose homeostasis are poorly understood. Thus, we aimed to pinpoint the main regulatory junctions at which weight cycling alters glucose homeostasis in mice. Using in vivo and ex vivo procedures we show that despite having worsened glucose tolerance, weight-cycled mice do not manifest impaired whole-body insulin action. Instead, weight cycling reduces insulin secretory capacity in vivo during clamped hyperglycemia and ex vivo in perifused islets. Islets from weight-cycled mice have reduced expression of drivers of b-cell identity (Mafa, Pdx1, Nkx6.1, Ucn3) and lower islet insulin content, compared to those from obese mice, suggesting inadequate transcriptional and posttranscriptional response to repeated nutrient overload. Collectively, these data support a model in which pancreatic plasticity is challenged in the face of large fluctuations in body weight resulting in a mismatch between glycemia and insulin secretion in mice.
2022-11-09 | GSE202697 | GEO
Project description:Glucagon receptor (GCGR) is a potential target for diabetes therapy. Several emerging GCGR antagonism-based therapies are under pre-clinical and clinical development. However, the GCGR antagonism as well as GCGR deficient animal accompanied with α-cell hyperplasia and hyperglucagonemia, which may limit the application of GCGR antagonism. To better understand the physiological changes in the α cells during the GCGR disruption, we performed the single cell sequencing of α cells isolated from control and gcgr-/- zebrafish. We found that α cells in gcgr-/- zebrafish dramatically increased glucagon (both gcga and gcgb) expression, we also found that several transcriptional factors that regulate glucagon expression were also increased. Based on the sequencing data, we further experimentally confirmed that gcgr-/- up-regulated glucagon mRNA level by in situ hybridization, and the gcgr-/- increased glucagon promoter activity indicated by reporter line Tg(gcga: GFP). Moreover, our results also revealed that α cells increased glucagon granule population and glucagon level in gcgr-/- zebrafish. These data suggested that hyperglucagonemia in the organism of GCGR antagonism not only contributed by the α-cell hyperplasia but also contributed by the increased glucagon expression and secretion from α cells. Our study provided more comprehensive understanding of physiological changes of α-cell during the GCGR disruption.
2022-10-26 | GSE179894 | GEO
Project description:Glucagon is secreted from pancreatic α-cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma by high-resolution-proteomics, we identified several glucagon variants among which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 was secreted in obese subjects before and as well after gastric bypass surgery with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β-cells demonstrated that PG 1-61 dose-dependently increased levels of cAMP, through the glucagon receptor, and increased insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. As a consequence, PG 1-61 increased blood glucose and plasma insulin and decreased plasma levels of amino acids in vivo. Glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion.
2017-10-20 | PXD005677 | Pride
Project description:Objective: Activation of the liver glucagon receptor (GCGR) promotes amino acid catabolism, which provides substrate for glucose production. Inhibition of the receptor downregulates hepatic amino acid catabolism, leading to increases in circulating amino acid levels. Amino acids serve as a potent growth factor for pancreatic alpha cells, where glucagon is produced. Thus, GCGR inhibition-induced hyperaminoacidemia causes alpha cell hyperplasia. This liver-alpha cell feedback loop, mediated by glucagon and amino acids, has been demonstrated across species, including humans. This study was designed to delineate hepatic signaling molecules that lie downstream of GCGR and mediate the liver-alpha cell loop. Methods: We used AAV8-shRNA to knock down GCGR signaling molecules, the G-coupled protein GNAS and two GNAS downstream effectors, PKA and EPAC2 (RAPGEF4), in the liver of diet-induced obese (DIO) mice. We monitored plasma amino acid and blood glucose levels and conducted pancreas histology to derive alpha and beta cell mass. We performed liver RNA-sequencing to assess expression of glucose and amino acid metabolism genes. To examine the contribution of PKA in changes associated with GCGR inhibition, we knocked down PRKAR1A, a major inhibitory subunit of PKA, to activate PKA in liver of mice administered with GCGR blocking or control antibody. Results: Comparable suppression of hepatic amino acid catabolism gene expressions, increases in plasma amino acid levels and alpha cell hyperplasia were observed in mice with hepatic knockdown of GCGR, GNAS, and PKA. Hepatic EPAC2 knockdown did not affect amino acid metabolism or alpha cell mass in mice. Mice with hepatic PKA activation alone developed hypoaminoacidemia, hypoglucagonemia and reduced alpha cell mass. Administering GCGR blocking antibody to the mice did not alter the abnormalities. Conclusions: Hepatic PKA activation in mice fully overrides the effect of GCGR inhibition on amino acids and alpha cells. In the liver, GCGR signals through PKA to control amino acid metabolism and pancreatic alpha cell mass. Hepatic PKA plays a critical role in the liver-alpha cell loop, mediated by circulating glucagon and amino acids.
2025-05-30 | GSE268864 | GEO