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1.
Nature ; 629(8014): 1133-1141, 2024 May.
Article in English | MEDLINE | ID: mdl-38750368

ABSTRACT

The N-methyl-D-aspartate (NMDA) receptor is a glutamate-activated cation channel that is critical to many processes in the brain. Genome-wide association studies suggest that glutamatergic neurotransmission and NMDA receptor-mediated synaptic plasticity are important for body weight homeostasis1. Here we report the engineering and preclinical development of a bimodal molecule that integrates NMDA receptor antagonism with glucagon-like peptide-1 (GLP-1) receptor agonism to effectively reverse obesity, hyperglycaemia and dyslipidaemia in rodent models of metabolic disease. GLP-1-directed delivery of the NMDA receptor antagonist MK-801 affects neuroplasticity in the hypothalamus and brainstem. Importantly, targeting of MK-801 to GLP-1 receptor-expressing brain regions circumvents adverse physiological and behavioural effects associated with MK-801 monotherapy. In summary, our approach demonstrates the feasibility of using peptide-mediated targeting to achieve cell-specific ionotropic receptor modulation and highlights the therapeutic potential of unimolecular mixed GLP-1 receptor agonism and NMDA receptor antagonism for safe and effective obesity treatment.


Subject(s)
Dizocilpine Maleate , Glucagon-Like Peptide 1 , Glucagon-Like Peptide-1 Receptor , Obesity , Receptors, N-Methyl-D-Aspartate , Receptors, N-Methyl-D-Aspartate/metabolism , Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors , Animals , Obesity/drug therapy , Obesity/metabolism , Glucagon-Like Peptide-1 Receptor/agonists , Glucagon-Like Peptide-1 Receptor/metabolism , Dizocilpine Maleate/pharmacology , Male , Rats , Humans , Glucagon-Like Peptide 1/metabolism , Mice , Neuronal Plasticity/drug effects , Hypothalamus/metabolism , Hypothalamus/drug effects , Hyperglycemia/drug therapy , Hyperglycemia/metabolism , Dyslipidemias/drug therapy , Dyslipidemias/metabolism , Disease Models, Animal , Brain Stem/metabolism , Brain Stem/drug effects , Female
2.
Mol Metab ; 83: 101915, 2024 May.
Article in English | MEDLINE | ID: mdl-38492844

ABSTRACT

OBJECTIVE: The glucose-dependent insulinotropic polypeptide (GIP) decreases body weight via central GIP receptor (GIPR) signaling, but the underlying mechanisms remain largely unknown. Here, we assessed whether GIP regulates body weight and glucose control via GIPR signaling in cells that express the leptin receptor (Lepr). METHODS: Hypothalamic, hindbrain, and pancreatic co-expression of Gipr and Lepr was assessed using single cell RNAseq analysis. Mice with deletion of Gipr in Lepr cells were generated and metabolically characterized for alterations in diet-induced obesity (DIO), glucose control and leptin sensitivity. Long-acting single- and dual-agonists at GIPR and GLP-1R were further used to assess drug effects on energy and glucose metabolism in DIO wildtype (WT) and Lepr-Gipr knock-out (KO) mice. RESULTS: Gipr and Lepr show strong co-expression in the pancreas, but not in the hypothalamus and hindbrain. DIO Lepr-Gipr KO mice are indistinguishable from WT controls related to body weight, food intake and diet-induced leptin resistance. Acyl-GIP and the GIPR:GLP-1R co-agonist MAR709 remain fully efficacious to decrease body weight and food intake in DIO Lepr-Gipr KO mice. Consistent with the demonstration that Gipr and Lepr highly co-localize in the endocrine pancreas, including the ß-cells, we find the superior glycemic effect of GIPR:GLP-1R co-agonism over single GLP-1R agonism to vanish in Lepr-Gipr KO mice. CONCLUSIONS: GIPR signaling in cells/neurons that express the leptin receptor is not implicated in the control of body weight or food intake, but is of crucial importance for the superior glycemic effects of GIPR:GLP-1R co-agonism relative to single GLP-1R agonism.


Subject(s)
Body Weight , Eating , Gastric Inhibitory Polypeptide , Mice, Knockout , Obesity , Receptors, Gastrointestinal Hormone , Receptors, Leptin , Animals , Male , Mice , Gastric Inhibitory Polypeptide/metabolism , Glucagon-Like Peptide 1/metabolism , Glucagon-Like Peptide-1 Receptor/metabolism , Glucagon-Like Peptide-1 Receptor/genetics , Glucose/metabolism , Leptin/metabolism , Mice, Inbred C57BL , Obesity/metabolism , Receptors, Gastrointestinal Hormone/metabolism , Receptors, Gastrointestinal Hormone/genetics , Receptors, Leptin/metabolism , Receptors, Leptin/genetics , Signal Transduction
3.
J Endocrinol ; 261(2)2024 May 01.
Article in English | MEDLINE | ID: mdl-38451873

ABSTRACT

The glucagon-like peptide 1 receptor (GLP-1R) is a class B G protein-coupled receptor (GPCR) that emerged as a pharmacologic target in cardiometabolic disease, including diabetes and obesity, over 30 years ago. The subsequent widespread clinical use of GLP-1R agonists, including exenatide, liraglutide, and semaglutide, has made the GLP-1R a preeminent model for understanding basic GPCR biology, including the emergent field of biased agonism. Recent data demonstrate that the dual GLP-1R/glucose dependent insulinotropic polypeptide receptor (GIPR) agonist tirzepatide exhibits a biased signaling profile characterized by preferential Gαs activation over ß-arrestin recruitment, which appears to contribute to its insulinotropic and body-weight reducing effects in preclinical models. This constitutes a major finding in which nuanced, mechanistic receptor signaling dynamics in vitro mediate real-world clinical differentiation within a drug class. Because of the striking bench-top-to-bed side relevance of this biased signaling phenomenon, we have undertaken a review of the emerging data detailing biased agonism at the GLP-1R. In this review, we introduce the core concept of biased agonism followed by a detailed consideration of the key mechanisms, including ligand-mediated bias, receptor-mediated bias, and systems/cell-type bias. Current industry programs are largely, if not entirely, focused on developing biased ligands, and so we have dedicated a section of the review to a brief meta-analysis of compounds reported to drive biased signaling, with a consideration of the structural determinants of receptor-ligand interactions. In this work, we aim to assess the current knowledge regarding signaling bias at the GLP-1R and how these ideas might be leveraged in future optimization.


Subject(s)
Liraglutide , Receptors, G-Protein-Coupled , Ligands , Liraglutide/pharmacology , Exenatide/pharmacology , Signal Transduction , Glucagon-Like Peptide-1 Receptor/agonists
4.
Nat Metab ; 5(12): 2075-2085, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37946085

ABSTRACT

The development of single-molecule co-agonists for the glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) is considered a breakthrough in the treatment of obesity and type 2 diabetes. But although GIPR-GLP-1R co-agonism decreases body weight with superior efficacy relative to GLP-1R agonism alone in preclinical1-3 and clinical studies4,5, the role of GIP in regulating energy metabolism remains enigmatic. Increasing evidence suggests that long-acting GIPR agonists act in the brain to decrease body weight through the inhibition of food intake3,6-8; however, the mechanisms and neuronal populations through which GIP affects metabolism remain to be identified. Here, we report that long-acting GIPR agonists and GIPR-GLP-1R co-agonists decrease body weight and food intake via inhibitory GABAergic neurons. We show that acyl-GIP decreases body weight and food intake in male diet-induced obese wild-type mice, but not in mice with deletion of Gipr in Vgat(also known as Slc32a1)-expressing GABAergic neurons (Vgat-Gipr knockout). Whereas the GIPR-GLP-1R co-agonist MAR709 leads, in male diet-induced obese wild-type mice, to greater weight loss and further inhibition of food intake relative to a pharmacokinetically matched acyl-GLP-1 control, this superiority over GLP-1 vanishes in Vgat-Gipr knockout mice. Our data demonstrate that long-acting GIPR agonists crucially depend on GIPR signaling in inhibitory GABAergic neurons to decrease body weight and food intake.


Subject(s)
Diabetes Mellitus, Type 2 , Male , Mice , Animals , Diabetes Mellitus, Type 2/metabolism , Gastric Inhibitory Polypeptide/metabolism , Obesity/metabolism , Glucagon-Like Peptide 1/metabolism , Receptors, G-Protein-Coupled , Glucose , GABAergic Neurons/metabolism , Eating
5.
Cell Metab ; 35(9): 1519-1529, 2023 09 05.
Article in English | MEDLINE | ID: mdl-37591245

ABSTRACT

The incretin system is an essential metabolic axis that regulates postprandial metabolism. The two incretin peptides that enable this effect are the glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide 1 (GLP-1), which have cognate receptors (GIPR and GLP-1R) on islet ß cells as well as in other tissues. Pharmacologic engagement of the GLP-1R is a proven strategy for treating hyperglycemia in diabetes and reducing body weight. Tirzepatide is the first monomeric peptide with dual activity at both incretin receptors now available for clinical use, and in clinical trials it has shown unprecedented effects to reduce blood glucose and body weight. Here, we discuss the foundational science that led to the development of monomeric multi-incretin receptor agonists, culminating in the development of tirzepatide. We also look to the future of this field and comment on how the concept of multi-receptor agonists will continue to progress for the treatment of metabolic disease.


Subject(s)
Diabetes Mellitus , Hyperglycemia , Humans , Incretins/therapeutic use , Diabetes Mellitus/drug therapy , Weight Loss , Body Weight , Receptors, G-Protein-Coupled
6.
Cardiovasc Diabetol ; 22(1): 217, 2023 08 17.
Article in English | MEDLINE | ID: mdl-37592302

ABSTRACT

BACKGROUND: Agonism at the receptor for the glucose-dependent insulinotropic polypeptide (GIPR) is a key component of the novel unimolecular GIPR:GLP-1R co-agonists, which are among the most promising drugs in clinical development for the treatment of obesity and type 2 diabetes. The therapeutic effect of chronic GIPR agonism to treat dyslipidemia and thus to reduce the cardiovascular disease risk independently of body weight loss has not been explored yet. METHODS: After 8 weeks on western diet, LDL receptor knockout (LDLR-/-) male mice were treated with daily subcutaneous injections of long-acting acylated GIP analog (acyl-GIP; 10nmol/kg body weight) for 28 days. Body weight, food intake, whole-body composition were monitored throughout the study. Fasting blood glucose and intraperitoneal glucose tolerance test (ipGTT) were determined on day 21 of the study. Circulating lipid levels, lipoprotein profiles and atherosclerotic lesion size was assessed at the end of the study. Acyl-GIP effects on fat depots were determined by histology and transcriptomics. RESULTS: Herein we found that treatment with acyl-GIP reduced dyslipidemia and atherogenesis in male LDLR-/- mice. Acyl-GIP administration resulted in smaller adipocytes within the inguinal fat depot and RNAseq analysis of the latter revealed that acyl-GIP may improve dyslipidemia by directly modulating lipid metabolism in this fat depot. CONCLUSIONS: This study identified an unanticipated efficacy of chronic GIPR agonism to improve dyslipidemia and cardiovascular disease independently of body weight loss, indicating that treatment with acyl-GIP may be a novel approach to alleviate cardiometabolic disease.


Subject(s)
Atherosclerosis , Cardiovascular Diseases , Diabetes Mellitus, Type 2 , Dyslipidemias , Male , Animals , Mice , Diabetes Mellitus, Type 2/drug therapy , Atherosclerosis/drug therapy , Atherosclerosis/genetics , Atherosclerosis/prevention & control , Dyslipidemias/drug therapy , Body Weight , Weight Loss
7.
Nat Metab ; 5(6): 945-954, 2023 06.
Article in English | MEDLINE | ID: mdl-37277609

ABSTRACT

The incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) mediate insulin responses that are proportionate to nutrient intake to facilitate glucose tolerance1. The GLP-1 receptor (GLP-1R) is an established drug target for the treatment of diabetes and obesity2, whereas the therapeutic potential of the GIP receptor (GIPR) is a subject of debate. Tirzepatide is an agonist at both the GIPR and GLP-1R and is a highly effective treatment for type 2 diabetes and obesity3,4. However, although tirzepatide activates GIPR in cell lines and mouse models, it is not clear whether or how dual agonism contributes to its therapeutic benefit. Islet beta cells express both the GLP-1R and the GIPR, and insulin secretion is an established mechanism by which incretin agonists improve glycemic control5. Here, we show that in mouse islets, tirzepatide stimulates insulin secretion predominantly through the GLP-1R, owing to reduced potency at the mouse GIPR. However, in human islets, antagonizing GIPR activity consistently decreases the insulin response to tirzepatide. Moreover, tirzepatide enhances glucagon secretion and somatostatin secretion in human islets. These data demonstrate that tirzepatide stimulates islet hormone secretion from human islets through both incretin receptors.


Subject(s)
Gastric Inhibitory Polypeptide , Hypoglycemic Agents , Incretins , Islets of Langerhans , Gastric Inhibitory Polypeptide/pharmacology , Humans , Animals , Mice , Glucagon-Like Peptide Receptors/agonists , Islets of Langerhans/drug effects , Incretins/pharmacology , Insulin/metabolism , Hypoglycemic Agents/pharmacology , Cells, Cultured
8.
Diabetologia ; 66(8): 1378-1394, 2023 08.
Article in English | MEDLINE | ID: mdl-37367959

ABSTRACT

The peptide hormone glucagon, discovered in late 1922, is secreted from pancreatic alpha cells and is an essential regulator of metabolic homeostasis. This review summarises experiences since the discovery of glucagon regarding basic and clinical aspects of this hormone and speculations on the future directions for glucagon biology and glucagon-based therapies. The review was based on the international glucagon conference, entitled 'A hundred years with glucagon and a hundred more', held in Copenhagen, Denmark, in November 2022. The scientific and therapeutic focus of glucagon biology has mainly been related to its role in diabetes. In type 1 diabetes, the glucose-raising properties of glucagon have been leveraged to therapeutically restore hypoglycaemia. The hyperglucagonaemia evident in type 2 diabetes has been proposed to contribute to hyperglycaemia, raising questions regarding underlying mechanism and the importance of this in the pathogenesis of diabetes. Mimicry experiments of glucagon signalling have fuelled the development of several pharmacological compounds including glucagon receptor (GCGR) antagonists, GCGR agonists and, more recently, dual and triple receptor agonists combining glucagon and incretin hormone receptor agonism. From these studies and from earlier observations in extreme cases of either glucagon deficiency or excess secretion, the physiological role of glucagon has expanded to also involve hepatic protein and lipid metabolism. The interplay between the pancreas and the liver, known as the liver-alpha cell axis, reflects the importance of glucagon for glucose, amino acid and lipid metabolism. In individuals with diabetes and fatty liver diseases, glucagon's hepatic actions may be partly impaired resulting in elevated levels of glucagonotropic amino acids, dyslipidaemia and hyperglucagonaemia, reflecting a new, so far largely unexplored pathophysiological phenomenon termed 'glucagon resistance'. Importantly, the hyperglucagonaemia as part of glucagon resistance may result in increased hepatic glucose production and hyperglycaemia. Emerging glucagon-based therapies show a beneficial impact on weight loss and fatty liver diseases and this has sparked a renewed interest in glucagon biology to enable further pharmacological pursuits.


Subject(s)
Diabetes Mellitus, Type 2 , Hyperglycemia , Non-alcoholic Fatty Liver Disease , Humans , Glucagon/metabolism , Diabetes Mellitus, Type 2/metabolism , Glucose/metabolism , Hyperglycemia/metabolism , Amino Acids
10.
Mol Metab ; 66: 101638, 2022 12.
Article in English | MEDLINE | ID: mdl-36400403

ABSTRACT

OBJECTIVE: Glucose-dependent insulinotropic polypeptide (GIP) is one of the two major incretin factors that regulate metabolic homeostasis. Genetic ablation of its receptor (GIPR) in mice confers protection against diet-induced obesity (DIO), while GIPR neutralizing antibodies produce additive weight reduction when combined with GLP-1R agonists in preclinical models and clinical trials. Conversely, GIPR agonists have been shown to promote weight loss in rodents, while dual GLP-1R/GIPR agonists have proven superior to GLP-1R monoagonists for weight reduction in clinical trials. We sought to develop a long-acting, specific GIPR peptide antagonist as a tool compound suitable for investigating GIPR pharmacology in both rodent and human systems. METHODS: We report a structure-activity relationship of GIPR peptide antagonists based on the human and mouse GIP sequences with fatty acid-based protraction. We assessed these compounds in vitro, in vivo in DIO mice, and ex vivo in islets from human donors. RESULTS: We report the discovery of a GIP(5-31) palmitoylated analogue, [Nα-Ac, L14, R18, E21] hGIP(5-31)-K11 (γE-C16), which potently inhibits in vitro GIP-mediated cAMP generation at both the hGIPR and mGIPR. In vivo, this peptide effectively blocks GIP-mediated reductions in glycemia in response to exogenous and endogenous GIP and displays a circulating pharmacokinetic profile amenable for once-daily dosing in rodents. Co-administration with the GLP-1R agonist semaglutide and this GIPR peptide antagonist potentiates weight loss compared to semaglutide alone. Finally, this antagonist inhibits GIP- but not GLP-1-stimulated insulin secretion in intact human islets. CONCLUSIONS: Our work demonstrates the discovery of a potent, specific, and long-acting GIPR peptide antagonist that effectively blocks GIP action in vitro, ex vivo in human islets, and in vivo in mice while producing additive weight-loss when combined with a GLP-1R agonist in DIO mice.


Subject(s)
Glucagon-Like Peptide-1 Receptor , Receptors, Gastrointestinal Hormone , Rodentia , Animals , Humans , Mice , Gastric Inhibitory Polypeptide/antagonists & inhibitors , Gastric Inhibitory Polypeptide/metabolism , Glucagon-Like Peptide 1/metabolism , Glucagon-Like Peptide-1 Receptor/metabolism , Mice, Obese , Peptides/pharmacology , Peptides/chemistry , Rodentia/metabolism , Weight Loss , Receptors, Gastrointestinal Hormone/antagonists & inhibitors
11.
Cell Metab ; 34(11): 1824-1842.e9, 2022 11 01.
Article in English | MEDLINE | ID: mdl-36243006

ABSTRACT

During mammalian energy homeostasis, the glucagon receptor (Gcgr) plays a key role in regulating both glucose and lipid metabolisms. However, the mechanisms by which these distinct signaling arms are differentially regulated remain poorly understood. Using a Cy5-glucagon agonist, we show that the endosomal protein Vps37a uncouples glucose production from lipid usage downstream of Gcgr signaling by altering intracellular receptor localization. Hepatocyte-specific knockdown of Vps37a causes an accumulation of Gcgr in endosomes, resulting in overactivation of the cAMP/PKA/p-Creb signaling pathway to gluconeogenesis without affecting ß-oxidation. Shifting the receptor back to the plasma membrane rescues the differential signaling and highlights the importance of the spatiotemporal localization of Gcgr for its metabolic effects. Importantly, since Vps37a knockdown in animals fed with a high-fat diet leads to hyperglycemia, although its overexpression reduces blood glucose levels, these data reveal a contribution of endosomal signaling to metabolic diseases that could be exploited for treatments of type 2 diabetes.


Subject(s)
Diabetes Mellitus, Type 2 , Receptors, Glucagon , Animals , Mice , Diabetes Mellitus, Type 2/metabolism , Endosomes/metabolism , Glucagon/metabolism , Glucose/metabolism , Lipids , Liver/metabolism , Mammals/metabolism , Mice, Inbred C57BL , Receptors, Glucagon/metabolism , Endosomal Sorting Complexes Required for Transport/metabolism
12.
Nat Metab ; 4(8): 1071-1083, 2022 08.
Article in English | MEDLINE | ID: mdl-35995995

ABSTRACT

Dual agonists activating the peroxisome proliferator-activated receptors alpha and gamma (PPARɑ/ɣ) have beneficial effects on glucose and lipid metabolism in patients with type 2 diabetes, but their development was discontinued due to potential adverse effects. Here we report the design and preclinical evaluation of a molecule that covalently links the PPARɑ/ɣ dual-agonist tesaglitazar to a GLP-1 receptor agonist (GLP-1RA) to allow for GLP-1R-dependent cellular delivery of tesaglitazar. GLP-1RA/tesaglitazar does not differ from the pharmacokinetically matched GLP-1RA in GLP-1R signalling, but shows GLP-1R-dependent PPARɣ-retinoic acid receptor heterodimerization and enhanced improvements of body weight, food intake and glucose metabolism relative to the GLP-1RA or tesaglitazar alone in obese male mice. The conjugate fails to affect body weight and glucose metabolism in GLP-1R knockout mice and shows preserved effects in obese mice at subthreshold doses for the GLP-1RA and tesaglitazar. Liquid chromatography-mass spectrometry-based proteomics identified PPAR regulated proteins in the hypothalamus that are acutely upregulated by GLP-1RA/tesaglitazar. Our data show that GLP-1RA/tesaglitazar improves glucose control with superior efficacy to the GLP-1RA or tesaglitazar alone and suggest that this conjugate might hold therapeutic value to acutely treat hyperglycaemia and insulin resistance.


Subject(s)
Diabetes Mellitus, Type 2 , PPAR alpha , Alkanesulfonates , Animals , Body Weight , Diabetes Mellitus, Type 2/drug therapy , Glucagon-Like Peptide 1/therapeutic use , Glucagon-Like Peptide-1 Receptor , Glucose , Male , Mice , Obesity/drug therapy , Obesity/metabolism , PPAR alpha/agonists , PPAR alpha/therapeutic use , Phenylpropionates
13.
Mol Metab ; 63: 101533, 2022 09.
Article in English | MEDLINE | ID: mdl-35809773

ABSTRACT

OBJECTIVE: Pharmacological strategies that engage multiple mechanisms-of-action have demonstrated synergistic benefits for metabolic disease in preclinical models. One approach, concurrent activation of the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon (Gcg) receptors (i.e. triagonism), combines the anorectic and insulinotropic activities of GLP-1 and GIP with the energy expenditure effect of glucagon. While the efficacy of triagonism in preclinical models is known, the relative contribution of GcgR activation remains unassessed. This work aims to addresses that central question. METHODS: Herein, we detail the design of unimolecular peptide triagonists with an empirically optimized receptor potency ratio. These optimized peptide triagonists employ a protraction strategy permitting once-weekly human dosing. Additionally, we assess the effects of these peptides on weight-reduction, food intake, glucose control, and energy expenditure in an established DIO mouse model compared to clinically relevant GLP-1R agonists (e.g. semaglutide) and dual GLP-1R/GIPR agonists (e.g. tirzepatide). RESULTS: Optimized triagonists normalize body weight in DIO mice and enhance energy expenditure in a manner superior to that of GLP-1R mono-agonists and GLP-1R/GIPR co-agonists. CONCLUSIONS: These pre-clinical data suggest unimolecular poly-pharmacology as an effective means to target multiple mechanisms contributing to obesity and further implicate GcgR activation as the differentiating factor between incretin receptor mono- or dual-agonists and triagonists.


Subject(s)
Gastric Inhibitory Polypeptide , Glucagon , Animals , Body Weight , Gastric Inhibitory Polypeptide/metabolism , Glucagon/metabolism , Glucagon-Like Peptide 1/metabolism , Humans , Mice , Mice, Obese , Peptides/pharmacology , Receptors, Glucagon/metabolism
14.
Diabetes ; 71(10): 2123-2135, 2022 10 01.
Article in English | MEDLINE | ID: mdl-35877180

ABSTRACT

Long-term glucagon receptor (GCGR) agonism is associated with hyperglycemia and glucose intolerance, while acute GCGR agonism enhances whole-body insulin sensitivity and hepatic AKTSer473 phosphorylation. These divergent effects establish a critical gap in knowledge surrounding GCGR action. mTOR complex 2 (mTORC2) is composed of seven proteins, including RICTOR, which dictates substrate binding and allows for targeting of AKTSer473. We used a liver-specific Rictor knockout mouse (RictorΔLiver) to investigate whether mTORC2 is necessary for insulin receptor (INSR) and GCGR cross talk. RictorΔLiver mice were characterized by impaired AKT signaling and glucose intolerance. Intriguingly, RictorΔLiver mice were also resistant to GCGR-stimulated hyperglycemia. Consistent with our prior report, GCGR agonism increased glucose infusion rate and suppressed hepatic glucose production during hyperinsulinemic-euglycemic clamp of control animals. However, these benefits to insulin sensitivity were ablated in RictorΔLiver mice. We observed diminished AKTSer473 and GSK3α/ßSer21/9 phosphorylation in RictorΔLiver mice, whereas phosphorylation of AKTThr308 was unaltered in livers from clamped mice. These signaling effects were replicated in primary hepatocytes isolated from RictorΔLiver and littermate control mice, confirming cell-autonomous cross talk between GCGR and INSR pathways. In summary, our study reveals the necessity of RICTOR, and thus mTORC2, in GCGR-mediated enhancement of liver and whole-body insulin action.


Subject(s)
Glucose Intolerance , Hyperglycemia , Insulin Resistance , Animals , Glucose/metabolism , Glucose Intolerance/metabolism , Homeostasis , Hyperglycemia/metabolism , Insulin/metabolism , Insulin/pharmacology , Insulin, Regular, Human , Liver/metabolism , Mechanistic Target of Rapamycin Complex 2/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Proto-Oncogene Proteins c-akt/metabolism , Rapamycin-Insensitive Companion of mTOR Protein , Receptor, Insulin/metabolism , Receptors, Glucagon/metabolism , TOR Serine-Threonine Kinases/metabolism
15.
Cell Metab ; 34(1): 3-4, 2022 01 04.
Article in English | MEDLINE | ID: mdl-34986336

ABSTRACT

In this issue, Bossart et al. report the in vivo receptor occupancy, body weight lowering effects in monkeys, and first-in-human results of SAR441255, a balanced GLP-1R/GIPR/GcgR triagonist. Following single doses to humans, SAR441255 shows positive acute glucoregulatory effects and an acceptable safety profile on gastrointestinal tolerability and cardiovascular hemodynamics.


Subject(s)
Glucagon , Receptors, Gastrointestinal Hormone , Glucagon-Like Peptide 1 , Glucagon-Like Peptide-1 Receptor , Humans , Receptors, Glucagon
16.
Front Endocrinol (Lausanne) ; 12: 693958, 2021.
Article in English | MEDLINE | ID: mdl-34484114

ABSTRACT

Optimization of peptides for therapeutic purposes often includes chemical conjugation or modification with substituents that serve to broaden pharmacology or improve pharmacokinetics. We report a convenient and rapid procedure for one-pot, site-specific conjugation of two cysteine-containing peptides that utilizes a bivalent linker comprising maleimide and iodoacetyl functional groups. Following maleimide-mediated peptide conjugation the linker was converted from an unstable thiosuccinimide to a stable thioether bond suitable for biological study by mild aqueous hydrolysis. The procedure is exemplified by peptide-peptide, peptide-small molecule, and peptide-fatty acid conjugations. The method provides a facile approach to search for enhanced biological outcomes through additive and sustained peptide pharmacology unencumbered by the prospect of chemical rearrangement in the course of biological study.


Subject(s)
Cysteine/chemistry , Polymers/chemical synthesis , Proglucagon/chemistry , Amino Acid Sequence , Animals , Cells, Cultured , Cricetinae , Cysteine/analogs & derivatives , Glucagon-Like Peptide-1 Receptor/agonists , Glucagon-Like Peptide-1 Receptor/metabolism , Humans , Maleimides/chemistry , Organic Chemistry Phenomena , Peptides/chemical synthesis , Peptides/chemistry , Polymers/chemistry
17.
J Med Chem ; 64(8): 4697-4708, 2021 04 22.
Article in English | MEDLINE | ID: mdl-33821647

ABSTRACT

Antagonism of glucagon's biological action is a proven strategy for decreasing glucose in diabetic animals and patients. To achieve full, potent, and selective suppression, we chemically optimized N-terminally truncated glucagon fragments for the identification and establishment of the minimum sequence peptide, [Glu9]glucagon(6-29) amide (11) as a full antagonist in cellular signaling and receptor binding (IC50 = 36 nM). Substitution of Phe6 with l-3-phenyllactic acid (Pla) produced [Pla6, Glu9]glucagon(6-29) amide (21), resulting in a 3-fold improvement in receptor binding (IC50 = 12 nM) and enhanced antagonist potency. Further substitution of Glu9 and Asn28 with aspartic acid yielded [Pla6, Asp28]glucagon amide (26), which demonstrated a further increase in inhibitory potency (IC50 = 9 nM), and improved aqueous solubility. Peptide 26 and a palmitoylated analogue, [Pla6, Lys10(γGluγGlu-C16), Asp28]glucagon(6-29) amide (31), displayed sustained duration in vivo action that successfully reversed glucagon-induced glucose elevation in mice.


Subject(s)
Glucagon/chemistry , Peptides/metabolism , Receptors, Glucagon/metabolism , Amides/chemistry , Amino Acid Sequence , Animals , Blood Glucose/analysis , Cyclic AMP/metabolism , Glucagon/administration & dosage , Glucagon-Like Peptide-1 Receptor/antagonists & inhibitors , Glucagon-Like Peptide-1 Receptor/metabolism , HEK293 Cells , Half-Life , Humans , Injections, Subcutaneous , Male , Mice , Mice, Inbred C57BL , Peptides/administration & dosage , Peptides/chemistry , Protein Binding , Receptors, Glucagon/antagonists & inhibitors , Solubility , Structure-Activity Relationship
18.
Nat Commun ; 12(1): 1041, 2021 02 15.
Article in English | MEDLINE | ID: mdl-33589633

ABSTRACT

Growing evidence supports that pharmacological application of growth differentiation factor 15 (GDF15) suppresses appetite but also promotes sickness-like behaviors in rodents via GDNF family receptor α-like (GFRAL)-dependent mechanisms. Conversely, the endogenous regulation of GDF15 and its physiological effects on energy homeostasis and behavior remain elusive. Here we show, in four independent human studies that prolonged endurance exercise increases circulating GDF15 to levels otherwise only observed in pathophysiological conditions. This exercise-induced increase can be recapitulated in mice and is accompanied by increased Gdf15 expression in the liver, skeletal muscle, and heart muscle. However, whereas pharmacological GDF15 inhibits appetite and suppresses voluntary running activity via GFRAL, the physiological induction of GDF15 by exercise does not. In summary, exercise-induced circulating GDF15 correlates with the duration of endurance exercise. Yet, higher GDF15 levels after exercise are not sufficient to evoke canonical pharmacological GDF15 effects on appetite or responsible for diminishing exercise motivation.


Subject(s)
Appetite Regulation/physiology , Exercise/physiology , Feeding Behavior/physiology , Glial Cell Line-Derived Neurotrophic Factor Receptors/genetics , Growth Differentiation Factor 15/genetics , Physical Endurance/physiology , Adult , Animals , Creatine Kinase/blood , Creatine Kinase/genetics , Gene Expression Regulation , Glial Cell Line-Derived Neurotrophic Factor Receptors/deficiency , Growth Differentiation Factor 15/blood , Growth Differentiation Factor 15/metabolism , Humans , Interleukin-10/blood , Interleukin-10/genetics , Interleukin-6/administration & dosage , Leptin/blood , Leptin/genetics , Liver/drug effects , Liver/metabolism , Male , Mice , Mice, Knockout , Motivation/physiology , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Myocardium/metabolism , Physical Conditioning, Animal , Time Factors
19.
Mol Metab ; 49: 101181, 2021 07.
Article in English | MEDLINE | ID: mdl-33556643

ABSTRACT

OBJECTIVE: We assessed the spatiotemporal GLP-1 and GIP receptor signaling, trafficking, and recycling dynamics of GIPR mono-agonists, GLP-1R mono-agonists including semaglutide, and GLP-1/GIP dual-agonists MAR709 and tirzepatide. METHODS: Receptor G protein recruitment and internalization/trafficking dynamics were assessed using bioluminescence resonance energy transfer (BRET)-based technology and live-cell HILO microscopy. RESULTS: Relative to native and acylated GLP-1 agonists, MAR709 and tirzepatide showed preserved maximal cAMP production despite partial Gαs recruitment paralleled by diminished ligand-induced receptor internalization at both target receptors. Despite MAR709's lower internalization rate, GLP-1R co-localization with Rab11-associated recycling endosomes was not different between MAR709 and GLP-1R specific mono-agonists. CONCLUSIONS: Our data indicated that MAR709 and tirzepatide induce unique spatiotemporal GLP-1 and GIP receptor signaling, trafficking, and recycling dynamics relative to native peptides, semaglutide, and matched mono-agonist controls. These findings support the hypothesis that the structure of GLP-1/GIP dual-agonists confer a biased agonism that, in addition to its influence on intracellular signaling, uniquely modulates receptor trafficking.


Subject(s)
Glucagon-Like Peptide 1/analogs & derivatives , Glucagon-Like Peptide 1/metabolism , Receptors, Gastrointestinal Hormone/metabolism , Signal Transduction/drug effects , Gastric Inhibitory Polypeptide/pharmacology , HEK293 Cells , Humans , Ligands , Peptides/pharmacology
20.
Cell Metab ; 33(4): 833-844.e5, 2021 04 06.
Article in English | MEDLINE | ID: mdl-33571454

ABSTRACT

Uncertainty exists as to whether the glucose-dependent insulinotropic polypeptide receptor (GIPR) should be activated or inhibited for the treatment of obesity. Gipr was recently demonstrated in hypothalamic feeding centers, but the physiological relevance of CNS Gipr remains unknown. Here we show that HFD-fed CNS-Gipr KO mice and humanized (h)GIPR knockin mice with CNS-hGIPR deletion show decreased body weight and improved glucose metabolism. In DIO mice, acute central and peripheral administration of acyl-GIP increases cFos neuronal activity in hypothalamic feeding centers, and this coincides with decreased body weight and food intake and improved glucose handling. Chronic central and peripheral administration of acyl-GIP lowers body weight and food intake in wild-type mice, but shows blunted/absent efficacy in CNS-Gipr KO mice. Also, the superior metabolic effect of GLP-1/GIP co-agonism relative to GLP-1 is extinguished in CNS-Gipr KO mice. Our data hence establish a key role of CNS Gipr for control of energy metabolism.


Subject(s)
Body Weight/drug effects , Eating/drug effects , Gastric Inhibitory Polypeptide/pharmacology , Receptors, Gastrointestinal Hormone/metabolism , Signal Transduction/drug effects , Animals , Central Nervous System/metabolism , Diet, High-Fat , Gastric Inhibitory Polypeptide/chemistry , Glucagon-Like Peptide 1/pharmacology , Humans , Hypothalamus/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Obesity/metabolism , Obesity/pathology , Obesity/prevention & control , Proto-Oncogene Proteins c-fos/metabolism , Receptors, Gastrointestinal Hormone/deficiency , Receptors, Gastrointestinal Hormone/genetics
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