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Larsen AT, Melander SA, Sonne N, Bredtoft E, Al-Rubai M, Karsdal MA, Henriksen K. Dual amylin and calcitonin receptor agonist treatment improves insulin sensitivity and increases muscle-specific glucose uptake independent of weight loss. Biomed Pharmacother 2023; 164:114969. [PMID: 37269811 DOI: 10.1016/j.biopha.2023.114969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/05/2023] Open
Abstract
Dual amylin and calcitonin receptor agonists (DACRAs) are known to induce significant weight loss as well as improve glucose tolerance, glucose control, and insulin action in rats. However, to what extent DACRAs affect insulin sensitivity beyond that induced by weight loss and if DACRAs affect glucose turnover including tissue-specific glucose uptake is still unknown. Hyperinsulinemic glucose clamp studies were carried out in pre-diabetic ZDSD and diabetic ZDF rats treated with either the DACRA KBP or the long-acting DACRA KBP-A for 12 days. The glucose rate of disappearance was assessed using 3-3H glucose and tissue-specific glucose uptake was evaluated using 14C-2-deoxy-D-glucose (14C-2DG). In diabetic ZDF rats, KBP treatment significantly reduced fasting blood glucose and improved insulin sensitivity independent of weight loss. Furthermore, KBP increased the rate of glucose clearance, likely by increasing glucose storage, but without altering the endogenous glucose production. This was confirmed in pre-diabetic ZDSD rats. Direct assessment of tissue-specific glucose uptake showed, that both KBP and KBP-A significantly increased glucose uptake in muscles. In summary, KBP treatment significantly improved insulin sensitivity in diabetic rats and markedly increased glucose uptake in muscles. Importantly, in addition to their well-established weight loss potential, the KBPs have an insulin-sensitizing effect independent of weight loss, highlighting DACRAs as promising agents for the treatment of type 2 diabetes and obesity.
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Affiliation(s)
| | | | | | | | | | - Morten A Karsdal
- Nordic Bioscience, 2730 Herlev, Denmark; KeyBioscience AG, Stans, Switzerland
| | - Kim Henriksen
- Nordic Bioscience, 2730 Herlev, Denmark; KeyBioscience AG, Stans, Switzerland
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2
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Kotliar IB, Lorenzen E, Schwenk JM, Hay DL, Sakmar TP. Elucidating the Interactome of G Protein-Coupled Receptors and Receptor Activity-Modifying Proteins. Pharmacol Rev 2023; 75:1-34. [PMID: 36757898 PMCID: PMC9832379 DOI: 10.1124/pharmrev.120.000180] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 09/27/2022] [Indexed: 12/13/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are known to interact with several other classes of integral membrane proteins that modulate their biology and pharmacology. However, the extent of these interactions and the mechanisms of their effects are not well understood. For example, one class of GPCR-interacting proteins, receptor activity-modifying proteins (RAMPs), comprise three related and ubiquitously expressed single-transmembrane span proteins. The RAMP family was discovered more than two decades ago, and since then GPCR-RAMP interactions and their functional consequences on receptor trafficking and ligand selectivity have been documented for several secretin (class B) GPCRs, most notably the calcitonin receptor-like receptor. Recent bioinformatics and multiplexed experimental studies suggest that GPCR-RAMP interactions might be much more widespread than previously anticipated. Recently, cryo-electron microscopy has provided high-resolution structures of GPCR-RAMP-ligand complexes, and drugs have been developed that target GPCR-RAMP complexes. In this review, we provide a summary of recent advances in techniques that allow the discovery of GPCR-RAMP interactions and their functional consequences and highlight prospects for future advances. We also provide an up-to-date list of reported GPCR-RAMP interactions based on a review of the current literature. SIGNIFICANCE STATEMENT: Receptor activity-modifying proteins (RAMPs) have emerged as modulators of many aspects of G protein-coupled receptor (GPCR)biology and pharmacology. The application of new methodologies to study membrane protein-protein interactions suggests that RAMPs interact with many more GPCRs than had been previously known. These findings, especially when combined with structural studies of membrane protein complexes, have significant implications for advancing GPCR-targeted drug discovery and the understanding of GPCR pharmacology, biology, and regulation.
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Affiliation(s)
- Ilana B Kotliar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York (I.B.K., E.L., T.P.S.); Tri-Institutional PhD Program in Chemical Biology, New York, New York (I.B.K.); Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Solna, Sweden (J.M.S.); Department of Pharmacology and Toxicology, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin, New Zealand (D.L.H.); and Department of Neurobiology, Care Sciences and Society (NVS), Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Solna, Sweden (T.P.S.)
| | - Emily Lorenzen
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York (I.B.K., E.L., T.P.S.); Tri-Institutional PhD Program in Chemical Biology, New York, New York (I.B.K.); Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Solna, Sweden (J.M.S.); Department of Pharmacology and Toxicology, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin, New Zealand (D.L.H.); and Department of Neurobiology, Care Sciences and Society (NVS), Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Solna, Sweden (T.P.S.)
| | - Jochen M Schwenk
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York (I.B.K., E.L., T.P.S.); Tri-Institutional PhD Program in Chemical Biology, New York, New York (I.B.K.); Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Solna, Sweden (J.M.S.); Department of Pharmacology and Toxicology, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin, New Zealand (D.L.H.); and Department of Neurobiology, Care Sciences and Society (NVS), Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Solna, Sweden (T.P.S.)
| | - Debbie L Hay
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York (I.B.K., E.L., T.P.S.); Tri-Institutional PhD Program in Chemical Biology, New York, New York (I.B.K.); Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Solna, Sweden (J.M.S.); Department of Pharmacology and Toxicology, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin, New Zealand (D.L.H.); and Department of Neurobiology, Care Sciences and Society (NVS), Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Solna, Sweden (T.P.S.)
| | - Thomas P Sakmar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York (I.B.K., E.L., T.P.S.); Tri-Institutional PhD Program in Chemical Biology, New York, New York (I.B.K.); Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Solna, Sweden (J.M.S.); Department of Pharmacology and Toxicology, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin, New Zealand (D.L.H.); and Department of Neurobiology, Care Sciences and Society (NVS), Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Solna, Sweden (T.P.S.)
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3
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Does receptor balance matter? – Comparing the efficacies of the dual amylin and calcitonin receptor agonists cagrilintide and KBP-336 on metabolic parameters in preclinical models. Biomed Pharmacother 2022; 156:113842. [DOI: 10.1016/j.biopha.2022.113842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 11/22/2022] Open
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4
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The Impact of Exposure Profile on the Efficacy of Dual Amylin and Calcitonin Receptor Agonist Therapy. Biomedicines 2022; 10:biomedicines10102365. [DOI: 10.3390/biomedicines10102365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/13/2022] [Accepted: 09/17/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Dual Amylin and Calcitonin Receptor Agonists (DACRAs) are treatment candidates for obesity and type 2 diabetes. Recently, a once-weekly DACRA (KBP-A) showed promise, potentially due to its different exposure profile compared to daily DACRA (KBP). Parathyroid hormone, a G-protein-coupled receptor (GPCR) class B agonist, is an example of the exposure profile being critical to the effect. Since KBP and KBP-A also activate GPCR class B, we compared the effects of injection to continuous infusion of short-acting KBP and long-acting KBP-A in obese and diabetic rats to shed light on the role of exposure profiles. Methods: To explore the metabolic benefits of dose optimization, the following dosing profiles were compared in High Fat Diet (HFD)-fed Sprague–Dawley rats and diabetic Zucker Diabetic Fatty (ZDF) rats: (1) KBP dosed once-daily by injection or by continuous infusion in HFD and ZDF rats; (2) KBP injected once-daily and KBP-A injected once every 3rd day (Q3D) in HFD rats; (3) KBP-A injected Q3D or by infusion in ZDF rats. Results: KBP and KBP-A, delivered by either injection or infusion, resulted in similar weight and food intake reductions in HFD rats. In ZDF rats, injection of KBP improved glucose control significantly compared to infusion, while delivery of KBP-A by injection and continuous infusion was comparable in terms of glucose control. Conclusion: different dosing profiles of KBP and KBP-A had no impact on metabolic benefits in HFD rats. In diabetic ZDF rats, KBP by injection instead of infusion was superior, while for KBP-A the effects were similar.
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Cao J, Belousoff MJ, Liang YL, Johnson RM, Josephs TM, Fletcher MM, Christopoulos A, Hay DL, Danev R, Wootten D, Sexton PM. A structural basis for amylin receptor phenotype. Science 2022; 375:eabm9609. [PMID: 35324283 DOI: 10.1126/science.abm9609] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Amylin receptors (AMYRs) are heterodimers of the calcitonin (CT) receptor (CTR) and one of three receptor activity-modifying proteins (RAMPs), AMY1R, AMY2R, and AMY3R. Selective AMYR agonists and dual AMYR/CTR agonists are being developed as obesity treatments; however, the molecular basis for peptide binding and selectivity is unknown. We determined the structure and dynamics of active AMYRs with amylin, AMY1R with salmon CT (sCT), AMY2R with sCT or human CT (hCT), and CTR with amylin, sCT, or hCT. The conformation of amylin-bound complexes was similar for all AMYRs, constrained by the RAMP, and an ordered midpeptide motif that we call the bypass motif. The CT-bound AMYR complexes were distinct, overlapping the CT-bound CTR complexes. Our findings indicate that activation of AMYRs by CT-based peptides is distinct from their activation by amylin-based peptides. This has important implications for the development of AMYR therapeutics.
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Affiliation(s)
- Jianjun Cao
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Matthew J Belousoff
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Yi-Lynn Liang
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Rachel M Johnson
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Tracy M Josephs
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Madeleine M Fletcher
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Debbie L Hay
- Department of Pharmacology and Toxicology, University of Otago, Dunedin 9054, New Zealand
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, N415, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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6
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Arrigoni S, Le Foll C, Cabak A, Lundh S, Raun K, John LM, Lutz TA. A selective role for receptor activity-modifying proteins in subchronic action of the amylin selective receptor agonist NN1213 compared with salmon calcitonin on body weight and food intake in male mice. Eur J Neurosci 2021; 54:4863-4876. [PMID: 34189795 PMCID: PMC8457108 DOI: 10.1111/ejn.15376] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/19/2022]
Abstract
The role of receptor activity‐modifying proteins (RAMPs) in modulating the pharmacological effects of an amylin receptor selective agonist (NN1213) or the dual amylin–calcitonin receptor agonist (DACRA), salmon calcitonin (sCT), was tested in three RAMP KO mouse models, RAMP1, RAMP3 and RAMP1/3 KO. Male wild‐type (WT) and knockout (KO) littermate mice were fed a 45% high‐fat diet for 20 weeks prior to the 3‐week treatment period. A decrease in body weight after NN1213 was observed in all WT mice, whereas sCT had no effect. The absence of RAMP1 had no significant effect on NN1213 efficacy, and sCT was still inactive. However, the absence of RAMP3 impeded NN1213 efficacy but improved sCT efficacy. Similar results were observed in RAMP1/3 KO suggesting that the amylin receptor 3 (AMY3 = CTR + RAMP3) is necessary for NN1213's maximal action on body weight and food intake and that the lack of AMY3 allowed sCT to be active. These results suggest that the chronic use of DACRA such as sCT can have unfavourable effect on body weight loss in mice (which differs from the situation in rats), whereas the use of the amylin receptor selective agonist does not. AMY3 seems to play a crucial role in modulating the action of these two compounds, but in opposite directions. The assessment of a long‐term effect of amylin and DACRA in different rodent models is necessary to understand potential physiological beneficial and unfavourable effects on weight loss before its transition to clinical trials.
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Affiliation(s)
- Soraya Arrigoni
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Andrea Cabak
- Global Research, Novo Nordisk AS, Måløv, Denmark
| | - Sofia Lundh
- Global Research, Novo Nordisk AS, Måløv, Denmark
| | - Kirsten Raun
- Global Research, Novo Nordisk AS, Måløv, Denmark
| | - Linu M John
- Global Research, Novo Nordisk AS, Måløv, Denmark
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
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7
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Andreassen KV, Larsen AT, Sonne N, Mohamed KE, Karsdal MA, Henriksen K. KBP-066A, a long-acting dual amylin and calcitonin receptor agonist, induces weight loss and improves glycemic control in obese and diabetic rats. Mol Metab 2021; 53:101282. [PMID: 34214708 PMCID: PMC8313742 DOI: 10.1016/j.molmet.2021.101282] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/22/2021] [Accepted: 06/22/2021] [Indexed: 11/17/2022] Open
Abstract
Objective Dual amylin and calcitonin receptor agonists (DACRAs) are novel therapeutic agents that not only improve insulin sensitivity but also work as an adjunct to established T2DM therapies. DACRAs are currently administered once daily, though it is unknown whether DACRAs with increased plasma half-life can be developed as a once-weekly therapy. Methods The in vitro potencies of the KBP-066A and KBP-066 (non-acylated) were assessed using reporter assays. Acylation functionality was investigated by a combination of pharmacokinetics and acute food intake in rats. in vivo efficacies were investigated head-to-head in obese (HFD) and T2D (ZDF) models. Results In in vitro, KBP-066A activated the CTR and AMY-R potently, with no off-target activity. Acylation functionality was confirmed by acute tests, as KBP-066A demonstrated a prolonged PK and PD response compared to KBP-066. Both compounds induced potent and dose-dependent weight loss in the HFD rat model. In ZDF rats, fasting blood glucose/fasting insulin levels (tAUC) were reduced by 39%/50% and 36%/47% for KBP-066 and KBP-066A, respectively. This effect resulted in a 31% and 46% vehicle-corrected reduction in HbA1c at the end of the study for KBP-066 and KBP-066A, respectively. Conclusions Here, we present pre-clinical data on an acylated DACRA, KBP-066A. The in vivo efficacy of KBP-066A is significantly improved compared to its non-acylated variant regarding weight loss and glycemic control in obese (HFD) and obese diabetic rats (ZDF). This compendium of pre-clinical studies highlights KBP-066A as a promising, once-weekly therapeutic agent for treating T2DM and obesity. DACRAs are promising once daily therapeutic candidates for metabolic diseases. We here present a novel DACRA called KBP-066A optimized for weekly delivery. KBP-066A potently reduced appetite and body weight in obese rats. More importantly, KBP-066A was superior to the corresponding daily DACRA in terms of glucose control. KBP-066A is a novel promising therapy for metabolic diseases.
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Affiliation(s)
| | - A T Larsen
- Nordic Bioscience A/S, Herlev, DK-2730, Denmark
| | - N Sonne
- Nordic Bioscience A/S, Herlev, DK-2730, Denmark
| | - K E Mohamed
- Nordic Bioscience A/S, Herlev, DK-2730, Denmark
| | - M A Karsdal
- Nordic Bioscience A/S, Herlev, DK-2730, Denmark; KeyBioscience AG, Stans, Switzerland
| | - K Henriksen
- Nordic Bioscience A/S, Herlev, DK-2730, Denmark; KeyBioscience AG, Stans, Switzerland.
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8
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Fletcher MM, Keov P, Truong TT, Mennen G, Hick CA, Zhao P, Furness SGB, Kruse T, Clausen TR, Wootten D, Sexton PM. AM833 Is a Novel Agonist of Calcitonin Family G Protein-Coupled Receptors: Pharmacological Comparison with Six Selective and Nonselective Agonists. J Pharmacol Exp Ther 2021; 377:417-440. [PMID: 33727283 DOI: 10.1124/jpet.121.000567] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/11/2021] [Indexed: 07/25/2024] Open
Abstract
Obesity and associated comorbidities are a major health burden, and novel therapeutics to help treat obesity are urgently needed. There is increasing evidence that targeting the amylin receptors (AMYRs), heterodimers of the calcitonin G protein-coupled receptor (CTR) and receptor activity-modifying proteins, improves weight control and has the potential to act additively with other treatments such as glucagon-like peptide-1 receptor agonists. Recent data indicate that AMYR agonists, which can also independently activate the CTR, may have improved efficacy for treating obesity, even though selective activation of CTRs is not efficacious. AM833 (cagrilintide) is a novel lipidated amylin analog that is undergoing clinical trials as a nonselective AMYR and CTR agonist. In the current study, we have investigated the pharmacology of AM833 across 25 endpoints and compared this peptide with AMYR selective and nonselective lipidated analogs (AM1213 and AM1784), and the clinically used peptide agonists pramlintide (AMYR selective) and salmon CT (nonselective). We also profiled human CT and rat amylin as prototypical selective agonists of CTR and AMYRs, respectively. Our results demonstrate that AM833 has a unique pharmacological profile across diverse measures of receptor binding, activation, and regulation. SIGNIFICANCE STATEMENT: AM833 is a novel nonselective agonist of calcitonin family receptors that has demonstrated efficacy for the treatment of obesity in phase 2 clinical trials. This study demonstrates that AM833 has a unique pharmacological profile across diverse measures of receptor binding, activation, and regulation when compared with other selective and nonselective calcitonin receptor and amylin receptor agonists. The present data provide mechanistic insight into the actions of AM833.
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Affiliation(s)
- Madeleine M Fletcher
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Peter Keov
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Tin T Truong
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Grace Mennen
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Caroline A Hick
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Peishen Zhao
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Sebastian G B Furness
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Thomas Kruse
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Trine R Clausen
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
| | - Patrick M Sexton
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (M.M.F., P.K., T.T.T., G.M., C.A.H., P.Z., S.G.B.F., D.W., P.M.S.); Research and Development, Novo Nordisk, Denmark (T.K., T.R.C.); and ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia (D.W., P.M.S.)
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Giansanti M, De Gabrieli A, Prete SP, Ottone T, Divona MD, Karimi T, Ciccarone F, Voso MT, Graziani G, Faraoni I. Poly(ADP-Ribose) Polymerase Inhibitors for Arsenic Trioxide-Resistant Acute Promyelocytic Leukemia: Synergistic In Vitro Antitumor Effects with Hypomethylating Agents or High-Dose Vitamin C. J Pharmacol Exp Ther 2021; 377:385-397. [PMID: 33820831 DOI: 10.1124/jpet.121.000537] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/29/2021] [Indexed: 11/22/2022] Open
Abstract
Arsenic trioxide (ATO) is an anticancer agent used for the treatment ofacute promyelocytic leukemia (APL). However, 5%-10% of patients fail to respond or experience disease relapse. Based on poly(ADP-ribose) polymerase (PARP) 1 involvement in the processing of DNA demethylation, here we have tested the in vitro susceptibility of ATO-resistant clones (derived from the human APL cell line NB4) to PARP inhibitors (PARPi) in combination with hypomethylating agents (azacitidine and decitabine) or high-dose vitamin C (ascorbate), which induces 5-hydroxymethylcytosine (5hmC)-mediated DNA demethylation. ATO-sensitive and -resistant APL cell clones were generated and initially analyzed for their susceptibility to five clinically used PARPi (olaparib, niraparib, rucaparib, veliparib, and talazoparib). The obtained PARPi IC50 values were far below (olaparib and niraparib), within the range (talazoparib), or above (rucaparib and veliparib) the C max reported in patients, likely as a result of differences in the mechanisms of their cytotoxic activity. ATO-resistant APL cells were also susceptible to clinically relevant concentrations of azacitidine and decitabine and to high-dose ascorbate. Interestingly, the combination of these agents with olaparib, niraparib, or talazoparib resulted in synergistic antitumor activity. In combination with ascorbate, PARPi increased the ascorbate-mediated induction of 5hmC, which likely resulted in stalled DNA repair and cytotoxicity. Talazoparib was the most effective PARPi in synergizing with ascorbate, in accordance with its marked ability to trap PARP1 at damaged DNA. These findings suggest that ATO and PARPi have nonoverlapping resistance mechanisms and support further investigation on PARPi combination with hypomethylating agents or high-dose ascorbate for relapsed/ATO-refractory APL, especially in frail patients. SIGNIFICANCE STATEMENT: This study found that poly(ADP-ribose) inhibitors (PARPi) show activity as single agents against human acute promyelocytic leukemia cells resistant to arsenic trioxide at clinically relevant concentrations. Furthermore, PARPi enhance the in vitro efficacy of azacitidine, decitabine, and high-dose vitamin C, all agents that alter DNA methylation. In combination with vitamin C, PARPi increase the levels of 5-hydroxymethylcytosine, likely as a result of altered processing of the oxidized intermediates associated with DNA demethylation.
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Affiliation(s)
- Manuela Giansanti
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Antonio De Gabrieli
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Salvatore Pasquale Prete
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Tiziana Ottone
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Maria Domenica Divona
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Terry Karimi
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Fabio Ciccarone
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Maria Teresa Voso
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Grazia Graziani
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
| | - Isabella Faraoni
- Pharmacology Section, Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy (M.G., A.D.G., S.P.P., T.K., G.G., I.F.); Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy (M.G.); Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy (T.O., M.D., M.T.V.); Unit of Neuro-Oncohematology, Santa Lucia Foundation-IRCCS, Rome, Italy (T.O., M.T.V.); and IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy (F.C.)
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Klockars A, Levine AS, Head MA, Perez-Leighton CE, Kotz CM, Olszewski PK. Impact of Gut and Metabolic Hormones on Feeding Reward. Compr Physiol 2021; 11:1425-1447. [PMID: 33577129 DOI: 10.1002/cphy.c190042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ingestion of food activates a cascade of endocrine responses (thereby reflecting a contemporaneous feeding status) that include the release of hormones from the gastrointestinal (GI) tract, such as cholecystokinin (CCK), glucagonlike peptide YY (PYY), peptide PP, and oleoylethanolamide, as well as suppression of ghrelin secretion. The pancreas and adipose tissue, on the other hand, release hormones that serve as a measure of the current metabolic state or the long-term energy stores, that is, insulin, leptin, and adiponectin. It is well known and intuitively understandable that these hormones target either directly (by crossing the blood-brain barrier) or indirectly (e.g., via vagal input) the "homeostatic" brainstem-hypothalamic pathways involved in the regulation of appetite. The current article focuses on yet another target of the metabolic and GI hormones that is critical in inducing changes in food intake, namely, the reward system. We discuss the physiological basis of this functional interaction, its importance in the control of appetite, and the impact that disruption of this crosstalk has on energy intake in select physiological and pathophysiological states. We conclude that metabolic and GI hormones have a capacity to strengthen or weaken a response of the reward system to a given food, and thus, they are fundamental in ensuring that feeding reward is plastic and dependent on the energy status of the organism. © 2021 American Physiological Society. Compr Physiol 11:1425-1447, 2021.
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Affiliation(s)
- Anica Klockars
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand
| | - Allen S Levine
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA
| | - Mitchell A Head
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand
| | | | - Catherine M Kotz
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA.,Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, USA
| | - Pawel K Olszewski
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand.,Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA.,Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, Minnesota, USA
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11
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Mono and dual agonists of the amylin, calcitonin, and CGRP receptors and their potential in metabolic diseases. Mol Metab 2020; 46:101109. [PMID: 33166741 PMCID: PMC8085567 DOI: 10.1016/j.molmet.2020.101109] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Therapies for metabolic diseases are numerous, yet improving insulin sensitivity beyond that induced by weight loss remains challenging. Therefore, search continues for novel treatment candidates that can stimulate insulin sensitivity and increase weight loss efficacy in combination with current treatment options. Calcitonin gene-related peptide (CGRP) and amylin belong to the same peptide family and have been explored as treatments for metabolic diseases. However, their full potential remains controversial. SCOPE OF REVIEW In this article, we introduce this rather complex peptide family and its corresponding receptors. We discuss the physiology of the peptides with a focus on metabolism and insulin sensitivity. We also thoroughly review the pharmacological potential of amylin, calcitonin, CGRP, and peptide derivatives as treatments for metabolic diseases, emphasizing their ability to increase insulin sensitivity based on preclinical and clinical studies. MAJOR CONCLUSIONS Amylin receptor agonists and dual amylin and calcitonin receptor agonists are relevant treatment candidates, especially because they increase insulin sensitivity while also assisting weight loss, and their unique mode of action complements incretin-based therapies. However, CGRP and its derivatives seem to have only modest if any metabolic effects and are no longer of interest as therapies for metabolic diseases.
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12
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Boccia L, Gamakharia S, Coester B, Whiting L, Lutz TA, Le Foll C. Amylin brain circuitry. Peptides 2020; 132:170366. [PMID: 32634450 DOI: 10.1016/j.peptides.2020.170366] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 12/14/2022]
Abstract
Amylin is a peptide hormone that is mainly known to be produced by pancreatic β-cells in response to a meal but amylin is also produced by brain cells in discrete brain areas albeit in a lesser amount. Amylin receptor (AMY) is composed of the calcitonin core-receptor (CTR) and one of the 3 receptor activity modifying protein (RAMP), thus forming AMY1-3; RAMP enhances amylin binding properties to the CTR. However, amylin receptor agonist such as salmon calcitonin is able to bind CTR alone. Peripheral amylin's main binding site is located in the area postrema (AP) which then propagate the signal to the nucleus of the solitary tract and lateral parabrachial nucleus (LPBN) and it is then transmitted to the forebrain areas such as central amygdala and bed nucleus of the stria terminalis. Amylin's activation of these different brain areas mediates eating and other metabolic pathways controlling energy expenditure and glucose homeostasis. Peripheral amylin can also bind in the arcuate nucleus of the hypothalamus where it acts independently of the AP to activate POMC and NPY neurons. Amylin activation of NPY neurons has been shown to be transmitted to LPBN neurons to act on eating while amylin POMC signaling affects energy expenditure and locomotor activity. While a large amount of experiments have already been conducted, future studies will have to further investigate how amylin is taken up by forebrain areas and deepen our understanding of amylin action on peripheral metabolism.
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Affiliation(s)
- Lavinia Boccia
- Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland
| | - Salome Gamakharia
- Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland
| | - Bernd Coester
- Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland
| | - Lynda Whiting
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Parkville, Australia
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland
| | - Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, CH-8057, Zurich, Switzerland.
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13
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Molecular interaction of an antagonistic amylin analog with the extracellular domain of receptor activity-modifying protein 2 assessed by fluorescence polarization. Biophys Chem 2020; 267:106477. [PMID: 33137565 DOI: 10.1016/j.bpc.2020.106477] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
The peptide hormone amylin receptor is a complex of the calcitonin receptor (CTR) and an accessory protein called receptor activity-modifying proteins (RAMPs). The soluble extracellular domain (ECD) of CTR is an important binding site of peptide hormone calcitonin. RAMPs also have an ECD and the association of CTR ECD with RAMP ECD enhances the affinity of peptide hormone amylin. However, the mechanism of how RAMP ECD association enhances amylin affinity remains elusive. Here, we report evidence supporting direct molecular interaction between an antagonistic amylin analog AC413 and RAMP2 ECD. We measured FITC-labeled peptide affinity for purified receptor ECD using fluorescence polarization (FP). We first found that RAMP2 ECD addition to maltose-binding protein (MBP)-tagged CTR ECD and an engineered MBP-tagged RAMP2 ECD-CTR ECD fusion protein (MBP-RAMP2-CTR ECD fusion) enhanced AC413 affinity. This suggests that these recombinant ECD systems represent functional amylin receptors. Interestingly, AC413 C-terminal residue Tyr25 (Y25) to Pro mutation eliminated its selective affinity for the MBP-RAMP2-CTR ECD fusion suggesting the critical role of the AC413 C-terminal residue in amylin receptor selectivity. Our structural model of the RAMP2 ECD:CTR ECD complex predicted molecular interaction of AC413 C-terminal residue Y25 with RAMP2 Glu101 (E101). Our FP peptide-binding assay showed that the RAMP2 E101A mutation of MBP-RAMP2-CTR ECD fusion decreased AC413 affinity by 7-fold, while the affinity of AC413 with the Y25P mutation was minimally changed. Consistently, AC413 binding affinity for the MBP-free RAMP2-CTR ECD fusion protein was also markedly decreased by the RAMP2 E101A mutation, while the affinity of AC413 with the Y25P mutation was moderately decreased. Together, our results support the molecular interaction between the AC413 C-terminal residue Y25 and RAMP2 E101 expanding our understanding of how the accessory protein RAMP2 enhances affinity of peptide hormone amylin for its receptor.
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