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Chen SD, Chuang YC, Lin TK, Yang JL. Alternative role of glucagon-like Peptide-1 receptor agonists in neurodegenerative diseases. Eur J Pharmacol 2022; 938:175439. [PMID: 36470445 DOI: 10.1016/j.ejphar.2022.175439] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 11/02/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022]
Abstract
Aging is a crucial risk factor for common neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). Limited options are available for the treatment of age-related, multiple pathogenic mechanism-contributed diseases that usually advance to irreversible conditions with severe neurological deficits and result in a heavy socioeconomic burden on patients, families, and society. A therapy that decelerates disease progression and reduces the socioeconomic burden stemming from these diseases is required. Glucagon-like peptide-1 receptor (GLP-1R) is an important class of medication for type 2 diabetes mellitus (T2DM). Through pancreatic effects, GLP-1R agonists can stimulate insulin secretion, increase β-cell proliferation, reduce β-cell apoptosis, and inhibit glucagon secretion in patients with T2DM. Currently, seven clinically approved GLP-1R agonists are used for T2DM: exenatide, liraglutide, lixisenatide, extended-release exenatide, albiglutide, dulaglutide, and semaglutide. Besides the pancreas, GLP-1Rs are also expressed in organs, such as the gastrointestinal tract, heart, lung, kidney, and brain, indicating their potential use in diseases other than T2DM. Emerging evidence reveals that GLP-1R agonists possess pleiotropic effects that enrich neurogenesis, diminish apoptosis, preclude neurons from oxidative stress, and reduce neuroinflammation in various neurological conditions. These favorable effects may also be employed in neurodegenerative diseases. Herein, we reviewed the recent progress, both in preclinical studies and clinical trials, regarding these clinically used GLP-1R agonists in aging-related neurodegenerative diseases, mainly AD and PD. We stress the pleiotropic characteristics of GLP-1R agonists as repurposing drugs to target multiple pathological mechanisms and for use in the future for these devastating neurodegenerative conditions.
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Affiliation(s)
- Shang-Der Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan; Institute for Translation Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan.
| | - Yao-Chung Chuang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan; Institute for Translation Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan; College of Medicine, Chang Gung University, Taoyuan City, 33302, Taiwan; Department of Neurology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, 80708, Taiwan.
| | - Tsu-Kung Lin
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan; College of Medicine, Chang Gung University, Taoyuan City, 33302, Taiwan; Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan.
| | - Jenq-Lin Yang
- Institute for Translation Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City, 83301, Taiwan.
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Assessing sequence-based protein-protein interaction predictors for use in therapeutic peptide engineering. Sci Rep 2022; 12:9610. [PMID: 35688894 PMCID: PMC9187631 DOI: 10.1038/s41598-022-13227-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 04/25/2022] [Indexed: 12/01/2022] Open
Abstract
Engineering peptides to achieve a desired therapeutic effect through the inhibition of a specific target activity or protein interaction is a non-trivial task. Few of the existing in silico peptide design algorithms generate target-specific peptides. Instead, many methods produce peptides that achieve a desired effect through an unknown mechanism. In contrast with resource-intensive high-throughput experiments, in silico screening is a cost-effective alternative that can prune the space of candidates when engineering target-specific peptides. Using a set of FDA-approved peptides we curated specifically for this task, we assess the applicability of several sequence-based protein–protein interaction predictors as a screening tool within the context of peptide therapeutic engineering. We show that similarity-based protein–protein interaction predictors are more suitable for this purpose than the state-of-the-art deep learning methods publicly available at the time of writing. We also show that this approach is mostly useful when designing new peptides against targets for which naturally-occurring interactors are already known, and that deploying it for de novo peptide engineering tasks may require gathering additional target-specific training data. Taken together, this work offers evidence that supports the use of similarity-based protein–protein interaction predictors for peptide therapeutic engineering, especially peptide analogs.
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3
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Winquist RJ, Gribkoff VK. Cardiovascular effects of GLP-1 receptor agonism. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 94:213-254. [PMID: 35659373 DOI: 10.1016/bs.apha.2022.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) receptor agonists are extensively used in type 2 diabetic patients for the effective control of hyperglycemia. It is now clear from outcomes trials that this class of drugs offers important additional benefits to these patients due to reducing the risk of developing major adverse cardiac events (MACE). This risk reduction is, in part, due to effective glycemic control in patients; however, the various outcomes trials, further validated by subsequent meta-analysis of the outcomes trials, suggest that the risk reduction in MACE is also dependent on glycemic-independent mechanisms operant in cardiovascular tissues. These glycemic-independent mechanisms are likely mediated by GLP-1 receptors found throughout the cardiovascular system and by the complex signaling cascades triggered by the binding of agonists to the G-protein coupled receptors. This heterogeneity of signaling pathways underlying different downstream effects of GLP-1 agonists, and the discovery of biased agonists favoring specific signaling pathways, may have import in the future treatment of MACE in these patients. We review the evidence supporting the glycemic-independent evidence for risk reduction of MACE by the GLP-1 receptor agonists and highlight the putative mechanisms underlying these benefits. We also comment on the different signaling pathways which appear important for mediating these effects.
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Affiliation(s)
| | - Valentin K Gribkoff
- Section on Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States; TheraStat LLC, Weston, MA, United States
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Siddiqui R, Maciver SK, Khan NA. Gut microbiome-immune system interaction in reptiles. J Appl Microbiol 2022; 132:2558-2571. [PMID: 34984778 DOI: 10.1111/jam.15438] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/12/2021] [Accepted: 12/31/2021] [Indexed: 12/17/2022]
Abstract
Reptiles are ectothermic amniotes in a world dominated by endotherms. Reptiles originated more than 300 million years ago and they often dwell in polluted environments which may expose them to pathogenic micro-organisms, radiation and/or heavy metals. Reptiles also possess greater longevity and may live much longer than similar-sized land mammals, for example, turtles, tortoises, crocodiles and tuatara are long-lived reptiles living up to 100 years or more. Many recent studies have emphasized the pivotal role of the gut microbiome on its host; thus, we postulated that reptilian gut microbiome and/or its metabolites and the interplay with their robust immune system may contribute to their longevity and overall hardiness. Herein, we discuss the composition of the reptilian gut microbiome, immune system-gut microbiome cross-talk, antimicrobial peptides, reptilian resistance to infectious diseases and cancer, ageing, as well the current knowledge of the genome and epigenome of these remarkable species. Preliminary studies have demonstrated that microbial gut flora of reptiles such as crocodiles, tortoises, water monitor lizard and python exhibit remarkable anticancer and antibacterial properties, as well as comprise novel gut bacterial metabolites and antimicrobial peptides. The underlying mechanisms between the gut microbiome and the immune system may hold clues to developing new therapies overall for health, and possible extrapolation to exploit the ancient defence systems of reptiles for Homo sapiens benefit.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- College of Arts and Sciences, American University of Sharjah, Sharjah, United Arab Emirates
| | - Sutherland K Maciver
- Centre for Discovery Brain Science, Edinburgh Medical School, Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Naveed Ahmed Khan
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
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5
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Stability and Safety of Inhibitor Cystine Knot Peptide, GTx1-15, from the Tarantula Spider Grammostola rosea. Toxins (Basel) 2021; 13:toxins13090621. [PMID: 34564625 PMCID: PMC8473062 DOI: 10.3390/toxins13090621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/29/2021] [Accepted: 09/01/2021] [Indexed: 12/19/2022] Open
Abstract
Inhibitor cystine knot (ICK) peptides are knotted peptides with three intramolecular disulfide bonds that affect several types of ion channels. Some are proteolytically stable and are promising scaffolds for drug development. GTx1-15 is an ICK peptide that inhibits the voltage-dependent calcium channel Cav3.1 and the voltage-dependent sodium channels Nav1.3 and Nav1.7. As a model molecule to develop an ICK peptide drug, we investigated several important pharmaceutical characteristics of GTx1-15. The stability of GTx1-15 in rat and human blood plasma was examined, and no GTx1-15 degradation was observed in either rat or human blood plasma for 24 h in vitro. GTx1-15 in blood circulation was detected for several hours after intravenous and intramuscular administration, indicating high stability in plasma. The thermal stability of GTx1-15 as examined by high thermal incubation and protein thermal shift assays indicated that GTx1-15 possesses high heat stability. The cytotoxicity and immunogenicity of GTx1-15 were examined using the human monocytic leukemia cell line THP-1. GTx1-15 showed no cytotoxicity or immunogenicity even at high concentrations. These results indicate that GTx1-15 itself is suitable for peptide drug development and as a peptide library scaffold.
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Abstract
Context: Heloderma bites are rare and generally mild, but a few cases can be life threatening. Methods: Description of Heloderma bite was searched in medical literature. Discussion: We present a synthesis of clinical and biomedical effects of envenomation by Heloderma sp. based on 22 well identified cases described in medical literature. Three life-threatening syndromes, concomitant or not, may be involved: (a) angioedema which can lead to respiratory tract obstruction, (b) significant fluid losses due to diarrhea, vomiting and sweating, associated with hypokalemia and sometimes metabolic acidosis, and (c) atrioventricular conduction disorders simulating cardiac ischemia. Conclusion: Heloderma bite are quite rare and generally mild. However, few severe cases may require emergency resuscitation. There is no antivenom, and the treatment is only symptomatic and supportive.
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Affiliation(s)
- Jean-Philippe Chippaux
- CRT, Institut Pasteur, Paris, France.,MERIT, IRD, Université Paris 5, Sorbonne Paris Cité, Paris, France
| | - Karim Amri
- Snakebite institute of Latin America, Belize, USA
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7
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Zhou W, Shao W, Zhang Y, Liu D, Liu M, Jin T. Glucagon-like peptide-1 receptor mediates the beneficial effect of liraglutide in an acute lung injury mouse model involving the thioredoxin-interacting protein. Am J Physiol Endocrinol Metab 2020; 319:E568-E578. [PMID: 32723174 PMCID: PMC7839242 DOI: 10.1152/ajpendo.00292.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Repurposing clinically used drugs is among the important strategies in drug discovery. Glucagon-like peptide-1 (GLP-1) and its diabetes-based drugs, such as liraglutide, possess a spectrum of extra-pancreatic functions, while GLP-1 receptor (GLP-1R) is most abundantly expressed in the lung. Recent studies have suggested that GLP-1-based drugs exert beneficial effects in chronic, as well as acute, lung injury rodent models. Here, we show that liraglutide pretreatment reduced LPS induced acute lung injury in mice. It significantly reduced lung injury score, wet/dry lung weight ratio, bronchoalveolar lavage fluid immune cell count and protein concentration, and cell apoptosis in the lung, and it was associated with reduced lung inflammatory cytokine and chemokine gene expression. Importantly, these effects were virtually absent in GLP-1R-/- mice. A well-known function of GLP-1 and GLP-based drugs in pancreatic β-cells is the attenuation of high-glucose stimulated expression of thioredoxin-interacting protein (TxNIP), a key component of inflammasome. LPS-challenged lungs showed elevated TxNIP mRNA and protein expression, which was attenuated by liraglutide treatment in a GLP-1R-dependent manner. Hence, our observations suggest that GLP-1R is essential in mediating beneficial effects of liraglutide in acute lung injury, with the inflammasome component TxNIP as a potential target.
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Affiliation(s)
- Wenyong Zhou
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Thoracic Surgery, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Weijuan Shao
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Yu Zhang
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Dinghui Liu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Cardiology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Mingyao Liu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Tianru Jin
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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8
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Abstract
BACKGROUND Heloderma bites are rare and generally mild, but a few cases can be life threatening. CASE REPORT We report a case of Heloderma suspectum envenomation in a healthy 39-year-old herpetologist. The patient rapidly developed tongue and lip swelling associated with stridor. On arrival at ICU, he was hypotensive, and in shock with atrial fibrillation requiring electrical cardioversion. Blood tests showed hypokalemia (2 mmol·L-1), associated with moderate low blood electrolytes which were corrected rapidly. In addition, he presented hematological abnormalities (INR = 1.34 and fibrinogen levels at 80 mg·dL-1) without active bleeding. All clinical and biological signs normalized without specific intervention and was discharged 4 days post-bite. The patient discharged 3 days after hospital presentation and fully recovered in 2 months. DISCUSSION/CONCLUSION The case presented here showed the three severe complications described after Heloderma bite: a) angioedema, b) fluid loss associated with hypokalemia and metabolic acidosis, and c) cardiac disorders simulating ischemia.
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Affiliation(s)
- Karim Amri
- Snakebite Institute of Latin America, Belize
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9
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Lee JY, Park T, Hong E, Amatya R, Park KA, Park YH, Min KA, Jin M, Lee S, Hwang S, Roh GS, Shin MC. Genetic engineering of novel super long-acting Exendin-4 chimeric protein for effective treatment of metabolic and cognitive complications of obesity. Biomaterials 2020; 257:120250. [PMID: 32736262 DOI: 10.1016/j.biomaterials.2020.120250] [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: 02/01/2020] [Revised: 06/21/2020] [Accepted: 07/17/2020] [Indexed: 02/08/2023]
Abstract
A common bottleneck challenge for many therapeutic proteins lies in their short plasma half-lives, which often makes the treatment far less compliant or even disables achieving sufficient therapeutic efficacy. To address this problem, we introduce a novel drug delivery strategy based on the genetic fusion of an albumin binding domain (ABD) and an anti-neonatal Fc receptor (FcRn) affibody (AFF) to therapeutic proteins. This ABD-AFF fusion strategy can provide a synergistic effect on extending the plasma residence time by, on one hand, preventing the rapid glomerular filtration via ABD-mediated albumin binding and, on the other hand, increasing the efficiency of FcRn-mediated recycling by AFF-mediated high-affinity binding to the FcRn. In this research, we explored the feasibility of applying the ABD-AFF fusion strategy to exendin-4 (EX), a clinically available anti-diabetic peptide possessing a short plasma half-life. The EX-ABD-AFF produced from the E. coli displayed a remarkably (241-fold) longer plasma half-life than the SUMO tagged-EX (SUMO-EX) (0.7 h) in mice. Furthermore, in high-fat diet (HFD)-fed obese mice model, the EX-ABD-AFF could provide significant hypoglycemic effects for over 12 days, accompanied by a reduction of body weight. In the long-term study, the EX-ABD-AFF could significantly reverse the obesity-related metabolic complications (hyperglycemia, hyperlipidemia, and hepatic steatosis) and, moreover, improve cognitive deficits. Overall, this study demonstrated that the ABD-AFF fusion could be an effective strategy to greatly increase the plasma half-lives of therapeutic proteins and thus markedly improve their druggability.
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Affiliation(s)
- Jong Youl Lee
- Department of Anatomy and Convergence Medical Science, Bio Anti-Aging Medical Research Center, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Taehoon Park
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju Daero, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Eunmi Hong
- New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation (DGMIF), Daegu, 41061, Republic of Korea
| | - Reeju Amatya
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju Daero, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Kyung-Ah Park
- Department of Anatomy and Convergence Medical Science, Bio Anti-Aging Medical Research Center, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju, Gyeongnam, 52727, Republic of Korea
| | - Young-Hoon Park
- New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation (DGMIF), Daegu, 41061, Republic of Korea
| | - Kyoung Ah Min
- College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Gyeongnam, 50834, Republic of Korea
| | - Minki Jin
- College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Gyeongnam, 50834, Republic of Korea
| | - Sumi Lee
- College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Gyeongnam, 50834, Republic of Korea
| | - Seungmi Hwang
- College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Gyeongnam, 50834, Republic of Korea
| | - Gu Seob Roh
- Department of Anatomy and Convergence Medical Science, Bio Anti-Aging Medical Research Center, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju, Gyeongnam, 52727, Republic of Korea.
| | - Meong Cheol Shin
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju Daero, Jinju, Gyeongnam, 52828, Republic of Korea.
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10
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Clough TJ, Baxan N, Coakley EJ, Rivas C, Zhao L, Leclerc I, Martinez-Sanchez A, Rutter GA, Long NJ. Synthesis and in vivo behaviour of an exendin-4-based MRI probe capable of β-cell-dependent contrast enhancement in the pancreas. Dalton Trans 2020; 49:4732-4740. [PMID: 32207493 PMCID: PMC7116436 DOI: 10.1039/d0dt00332h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Global rates of diabetes mellitus are increasing, and treatment of the disease consumes a growing proportion of healthcare spending across the world. Pancreatic β-cells, responsible for insulin production, decline in mass in type 1 and, to a more limited degree, in type 2 diabetes. However, the extent and rate of loss in both diseases differs between patients resulting in the need for the development of novel diagnostic tools, which could quantitatively assess changes in mass of β-cells over time and potentially lead to earlier diagnosis and improved treatments. Exendin-4, a potent analogue of glucagon-like-peptide 1 (GLP-1), binds to the receptor GLP-1R, whose expression is enriched in β-cells. GLP-1R has thus been used in the past as a means of targeting probes for a wide variety of imaging modalities to the endocrine pancreas. However, exendin-4 conjugates designed specifically for MRI contrast agents are an under-explored area. In the present work, the synthesis and characterization of an exendin-4-dota(ga)-Gd(iii) complex, GdEx, is reported, along with its in vivo behaviour in healthy and in β-cell-depleted C57BL/6J mice. Compared to the ubiquitous probe, [Gd(dota)]-, GdEx shows selective uptake by the pancreas with a marked decrease in accumulation observed after the loss of β-cells elicited by deleting the microRNA processing enzyme, DICER. These results open up pathways towards the development of other targeted MRI contrast agents based on similar chemistry methodology.
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Affiliation(s)
- Thomas J Clough
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London, W12 0BZ, UK.
| | - Nicoleta Baxan
- Biological Imaging Centre, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Emma J Coakley
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London, W12 0BZ, UK.
| | - Charlotte Rivas
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London, W12 0BZ, UK.
| | - Lan Zhao
- Biological Imaging Centre, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK and National Heart and Lung Institute, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Aida Martinez-Sanchez
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK. and Lee Kong Chain School of Medicine, Nan Yang Technological University, 11 Mandalay Road, 308232 Singapore
| | - Nicholas J Long
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London, W12 0BZ, UK.
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11
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Qiao Y, Yu G, Kratch KC, Wang XA, Wang WW, Leeuwon SZ, Xu S, Morse JS, Liu WR. Expressed Protein Ligation without Intein. J Am Chem Soc 2020; 142:7047-7054. [PMID: 32212692 DOI: 10.1021/jacs.0c00252] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Proteins with a functionalized C-terminus such as a C-terminal thioester are key to the synthesis of larger proteins via expressed protein ligation. They are usually made by recombinant fusion to intein. Although powerful, the intein fusion approach suffers from premature hydrolysis and low compatibility with denatured conditions. To totally bypass the involvement of an enzyme for expressed protein ligation, here we showed that a cysteine in a recombinant protein was chemically activated by a small molecule cyanylating reagent at its N-side amide for undergoing nucleophilic acyl substitution with amines including a number of l- and d-amino acids and hydrazine. The afforded protein hydrazides could be used further for expressed protein ligation. We demonstrated the versatility of this activated cysteine-directed protein ligation (ACPL) approach with the successful synthesis of ubiquitin conjugates, ubiquitin-like protein conjugates, histone H2A with a C-terminal posttranslational modification, RNase H that actively hydrolyzed RNA, and exenatide that is a commercial therapeutic peptide. The technique, which is exceedingly simple but highly useful, expands to a great extent the synthetic capacity of protein chemistry and will therefore make a large avenue of new research possible.
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Affiliation(s)
- Yuchen Qiao
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Ge Yu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Kaci C Kratch
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Xiaoyan Aria Wang
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Wesley Wei Wang
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Sunshine Z Leeuwon
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Shiqing Xu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Jared S Morse
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Wenshe Ray Liu
- The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.,Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77843, United States.,Molecular & Cellular Medicine Department, College of Medicine, Texas A&M University, College Station, Texas 77843, United States
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12
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Sheehy DF, Quinnell SP, Vegas AJ. Targeting Type 1 Diabetes: Selective Approaches for New Therapies. Biochemistry 2019; 58:214-233. [PMID: 30608114 DOI: 10.1021/acs.biochem.8b01118] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The clinical onset of type 1 diabetes is characterized by the destruction of the insulin-producing β cells of the pancreas and is caused by autoantigen-induced inflammation (insulitis) of the islets of Langerhans. The current standard of care for type 1 diabetes mellitus patients allows for management of the disease with exogenous insulin, but patients eventually succumb to many chronic complications such as limb amputation, blindness, and kidney failure. New therapeutic approaches now on the horizon are looking beyond glycemic management and are evaluating new strategies from protecting and regenerating endogenous islets to treating the underlying autoimmunity through selective modulation of key immune cell populations. Currently, there are no effective treatments for the autoimmunity that causes the disease, and strategies that aim to delay or prevent the onset of the disease will play an important role in the future of diabetes research. In this review, we summarize many of the key efforts underway that utilize molecular approaches to selectively modulate this disease and look at new therapeutic paradigms that can transform clinical treatment.
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Affiliation(s)
- Daniel F Sheehy
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Sean P Quinnell
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Arturo J Vegas
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
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13
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Irwin DM. Viral Insulin/IGF-1-Like Peptides: Novel Regulators of Physiology and Pathophysiology? Endocrinology 2018; 159:3659-3660. [PMID: 30304404 DOI: 10.1210/en.2018-00856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 11/19/2022]
Affiliation(s)
- David M Irwin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Center, University of Toronto, Toronto, Ontario, Canada
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14
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Pathak NM, Millar PJB, Pathak V, Flatt PR, Gault VA. Beneficial metabolic effects of dietary epigallocatechin gallate alone and in combination with exendin-4 in high fat diabetic mice. Mol Cell Endocrinol 2018; 460:200-208. [PMID: 28754350 DOI: 10.1016/j.mce.2017.07.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/24/2017] [Accepted: 07/24/2017] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Significant attempts are being made to generate multifunctional, hybrid or peptide combinations as novel therapeutic strategies for type 2 diabetes, however this presents key challenges including design and pharmaceutical development. In this study, we evaluated metabolic properties of oral nutritional supplement epigallocatechin gallate (EGCG) in combination with GLP-1 agonist exendin-4 in a mouse model of dietary-induced diabetes and obesity. METHODS EGCG, exendin-4 or combination of both were administered twice-daily over 28 days to high fat (HF) mice on background of low-dose streptozotocin. Energy intake, body weight, fat mass, glucose tolerance, insulin sensitivity, lipid profile, biochemical and hormone markers, and islet histology were examined. RESULTS All treatment groups exhibited significantly reduced body weight, fat mass, circulating glucose and insulin concentrations, and HbA1c levels which were independent of changes in energy intake. Similarly, there was marked improvement in glycaemic control, glucose-stimulated insulin release, insulin sensitivity, total cholesterol and triglycerides, with most prominent effects observed following combination therapy. Circulating corticosterone concentrations and 11beta-hydroxysteroid dehydrogenase type1 (11β-HSD1) staining (in pancreas) were beneficially decreased without changes in circulating interleukin 6 (IL-6), alanine transaminase (ALT) and glutathione reductase. Combination therapy resulted in increased islet area and number, beta cell area, and pancreatic insulin content. Generally, metabolic effects were much more pronounced in mice which received combination therapy. CONCLUSIONS EGCG alone and particularly in combination with exendin-4 exerts positive metabolic properties in HF mice. EGCG may be useful dietary adjunct alongside GLP-1 mimetics in treatment of diabetes and related disorders.
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Affiliation(s)
- Nupur M Pathak
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Paul J B Millar
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Varun Pathak
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Peter R Flatt
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Victor A Gault
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, United Kingdom.
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15
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Pennington MW, Czerwinski A, Norton RS. Peptide therapeutics from venom: Current status and potential. Bioorg Med Chem 2017; 26:2738-2758. [PMID: 28988749 DOI: 10.1016/j.bmc.2017.09.029] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 12/19/2022]
Abstract
Peptides are recognized as being highly selective, potent and relatively safe as potential therapeutics. Peptides isolated from the venom of different animals satisfy most of these criteria with the possible exception of safety, but when isolated as single compounds and used at appropriate concentrations, venom-derived peptides can become useful drugs. Although the number of venom-derived peptides that have successfully progressed to the clinic is currently limited, the prospects for venom-derived peptides look very optimistic. As proteomic and transcriptomic approaches continue to identify new sequences, the potential of venom-derived peptides to find applications as therapeutics, cosmetics and insecticides grows accordingly.
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Affiliation(s)
| | - Andrzej Czerwinski
- Peptides International, Inc., 11621 Electron Drive, Louisville, KY 40299, USA
| | - Raymond S Norton
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, 3052, Australia
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16
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Odegard PS, Setter SM, Iltz JL. Update in the Pharmacologic Treatment of Diabetes Mellitus. DIABETES EDUCATOR 2016; 32:693-712. [PMID: 16971704 DOI: 10.1177/0145721706294003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
There are now more than 20 million people in America with diabetes mellitus (DM), and the prevalence of this illness continues to increase especially in those with type 2 DM. Over the past decade, research in the area of DM treatment has focused on pharmacologic approaches to modifying glucose metabolism as well as on lifestyle interventions to prevent and manage DM. Pharmacologic research has been guided by an improved understanding of the human physiology of glucose metabolism, allowing for development of new hormonal drug therapies and improved insulin formulations. As a result, there are several new pharmacologic treatments now available or on the horizon for DM. In this article, the authors review the first of the new hormonal therapies for DM, with a focus on information that will be useful for diabetes educators including the medication actions, side effects, patient counseling points, monitoring, and place in therapy in comparison to existing DM treatments. This series on new therapies has been divided into 3 parts, with this first part devoted to an update on the new incretin mimetic and amylin analog agents recently approved for use in DM. Subsequent parts in this series will focus on the new insulin products and oral therapies available or soon to be available. Cases will be used to assist with understanding the type of patient who will benefit from each of these new therapies.
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Affiliation(s)
- Peggy Soule Odegard
- The School of Pharmacy, University of Washington, Seattle, and Evergreen Senior Health Specialists, Kirkland, Washington (Dr Odegard)
| | - Stephen M Setter
- The College of Pharmacy, Washington State University, Spokane (Dr Setter, Dr Iltz)
| | - Jason L Iltz
- The College of Pharmacy, Washington State University, Spokane (Dr Setter, Dr Iltz)
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17
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Yoo BK, Triller DM, Yoo DJ. Formulary Forum: Exenatide: A New Option for the Treatment of Type 2 Diabetes. Ann Pharmacother 2016; 40:1777-84. [PMID: 16985091 DOI: 10.1345/aph.1h060] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Objective: To evaluate available literature characterizing the pharmacology, pharmacokinetics, drug interactions, efficacy, and safety of exenatide in patients with type 2 diabetes. Data Sources: A PubMed database search (1966–May 2006) was conducted, using exenatide as the search term. The manufacturer's prescribing information was also used. Study Selection and Data Extraction: English-language articles were selected and data were extracted with a focus on clinical outcomes associated with the treatment of patients with type 2 diabetes. Data Synthesis: Exenatide exerts a glucoregulatory effect by various mechanisms including secretion of glucose-dependent insulin, suppression of inappropriately high glucagon levels in patients with type 2 diabetes, delayed gastric emptying, and reduction of food intake. In placebo-controlled clinical studies, plasma exenatide concentrations appeared to exhibit dose-proportional kinetics, reaching peak plasma levels between 2 and 3 hours after a single subcutaneous injection. Exenatide's elimination half-life ranged from 3.3 to 4.0 hours, and the time to reach maximum concentration was about 2 hours. Interactions between exenatide and agents such as digoxin and lisinopril were not considered significant. In Phase III trials, exenatide demonstrated significant reduction of hemoglobin A1c levels from baseline and compared with placebo after 30 weeks of treatment in patients unable to achieve optimal glycemic control with metformin, a sulfonylurea, or oral combination therapy (0.4–0.9%). Patients' weight decreased with exenatide (0.9–2.8 kg), but adverse gastrointestinal (GI) events were common. Exenatide combined with thiazolidonediones, D-phenylalanine derivatives, meglitinides, or alpha glucosidase inhibitors has not been studied. Conclusions: Clinical trials have demonstrated that exenatide improves glycemic control when added to sulfonylureas and metformin, and it may be an alternative to insulin glargine in patients requiring additional therapy. Hypoglycemia has been encountered in clinical trials of exenatide, especially upon initiation of therapy with sulfonylureas (not with metformin); close patient monitoring is therefore recommended. Further studies should assess the impact of exenatide on clinical outcomes such as micro- and macrovascular disease.
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Affiliation(s)
- Bong Kyu Yoo
- Department of Pharmacy Practice, College of Pharmacy, Yeungnam University, Kyungsan, Kyungbuk, Korea.
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18
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Park EJ, Lim SM, Lee KC, Na DH. Exendins and exendin analogs for diabetic therapy: a patent review (2012-2015). Expert Opin Ther Pat 2016; 26:833-42. [DOI: 10.1080/13543776.2016.1192130] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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19
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Irwin DM. Evolution of receptors for peptides similar to glucagon. Gen Comp Endocrinol 2014; 209:50-60. [PMID: 24650782 DOI: 10.1016/j.ygcen.2014.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/24/2014] [Accepted: 03/05/2014] [Indexed: 12/25/2022]
Abstract
The genes encoding the peptide precursors for glucagon (GCG), glucose-dependent insulinotropic peptide (GIP), and ortholog of exendin belong to the same family as shown by sequence similarity. The peptides similar to glucagon encoded by these genes signal through a closely related subfamily of G-protein coupled receptors. A total of five types of genes for receptors for these peptides have been identified, three for the products of GCG (GCGR, GLP1R, and GLP2R) and one each for the products of GIP (GIPR) and the ortholog of exendin (Grlr). Phylogenetic and genomic neighborhood analyses clearly show that these genes originated very early in vertebrate evolution and all were present in the common ancestor of tetrapods and bony fish. Despite their ancient origins, some of these genes are dispensable, with the Glp1r, Gipr, and Grlr being lost on the lineages leading to bony fish, birds, and mammals, respectively. The loss of the genes for these receptors may have been driving forces in the evolution of new functions for these peptides similar to glucagon.
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Affiliation(s)
- David M Irwin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ont. M5S 1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, Ont. M5S 1A8, Canada.
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20
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Mo GX, Bai XW, Li ZJ, Yan XW, He XQ, Rong MQ. A Novel Insulinotropic Peptide from the Skin Secretions of Amolops loloensis Frog. NATURAL PRODUCTS AND BIOPROSPECTING 2014; 4:309-13. [PMID: 25294221 PMCID: PMC4199949 DOI: 10.1007/s13659-014-0037-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/21/2014] [Indexed: 05/12/2023]
Abstract
Various kinds of biologically active peptides have previously been isolated from the skin secretions of Amolops loloensis frog, such as antimicrobial peptides, bradykinin-like peptides and algesic peptides. A novel insulinotropic peptide named amolopin was identified in A. loloensis frog's skin secretion. Its primary structure sequence was determined by Edman degradation as: FLPIVGKSLSGLSGKL-NH2. BLAST search indicates that the amino acid sequence of amolopin is quite different from other known insulin secretagogues, including mastoparan, exendins and α-latrotoxin, nor does it like incretins (e.g. glucagons like peptide-1 and glucose-dependent insulinotropic ploypeptide) either. However, amolopin shows certain structural similarity with amphibian antimicrobial temporins and vespid chemotactic peptides isolated from Vespa magnifica. Amolopin can stimulate insulin release in INS-1 cells in a dose-dependent manner. Primary investigation on its action mechanisms reveals that amolopin does not increase the influx of Ca(2+). In conclusion, a novel 16-amino acid peptide with insulin-releasing activity is initially discovered from the skin secretion of A. loloensis frog. Further work is necessary to evaluate its potential as novel anti-diabetic candidate.
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Affiliation(s)
- Guo-Xiang Mo
- School of Biological Sciences, Nanjing Agriculture University, Nanjing, 210095 Jiangshu China
| | - Xue-Wei Bai
- School of Biological Sciences, Nanjing Agriculture University, Nanjing, 210095 Jiangshu China
| | - Zong-Jie Li
- School of Biological Sciences, Nanjing Agriculture University, Nanjing, 210095 Jiangshu China
| | - Xiu-Wen Yan
- School of Biological Sciences, Nanjing Agriculture University, Nanjing, 210095 Jiangshu China
| | - Xiao-Qing He
- Kunming Institue of Zoology, Chinese Academy of Sciences, Kunming, 650223 Yunnan China
| | - Ming-Qiang Rong
- Kunming Institue of Zoology, Chinese Academy of Sciences, Kunming, 650223 Yunnan China
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21
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Levy OE, Jodka CM, Ren SS, Mamedova L, Sharma A, Samant M, D’Souza LJ, Soares CJ, Yuskin DR, Jin LJ, Parkes DG, Tatarkiewicz K, Ghosh SS. Novel exenatide analogs with peptidic albumin binding domains: potent anti-diabetic agents with extended duration of action. PLoS One 2014; 9:e87704. [PMID: 24503632 PMCID: PMC3913652 DOI: 10.1371/journal.pone.0087704] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/01/2014] [Indexed: 11/19/2022] Open
Abstract
The design, synthesis and pharmacology of novel long-acting exenatide analogs for the treatment of metabolic diseases are described. These molecules display enhanced pharmacokinetic profile and potent glucoregulatory and weight lowering actions compared to native exenatide. [Leu(14)]exenatide-ABD is an 88 residue peptide amide incorporating an Albumin Binding Domain (ABD) scaffold. [Leu(14)]exenatide-ABP is a 53 residue peptide incorporating a short Albumin Binding Peptide (ABP). [Leu(14)]exenatide-ABD and [Leu(14)]exenatide-ABP exhibited nanomolar functional GLP-1 receptor potency and were metabolically stable in vitro in human plasma and in a pancreatic digestive enzyme mixture. Both molecules displayed picomolar and nanomolar binding association with albumin across multiple species and circulating half lives of 16 and 11 hours, respectively, post a single IV dose in rats. Unlike exenatide, both molecules elicited robust glucose lowering when injected 1 day prior to an oral glucose tolerance test, indicative of their extended duration of action. [Leu(14)]exenatide-ABD was compared to exenatide in a Lep (ob/ob) mouse model of diabetes. Twice-weekly subcutaneously dosed [Leu(14)]exenatide-ABD displayed superior glucose lowering and weight loss in diabetic mice when compared to continuously infused exenatide at the same total weekly dose. A single oral administration of each molecule via an enteric coated capsule to cynomolgus monkeys showed superior pharmacokinetics for [Leu(14)]exenatide-ABD as compared to [Leu(14)]exenatide-ABP with detectable exposure longer than 14 days. These studies support the potential use of these novel long acting exenatide analogs with different routes of administration for the treatment of type 2 diabetes.
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Affiliation(s)
- Odile E. Levy
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Carolyn M. Jodka
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Shijun Steven Ren
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Lala Mamedova
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Abhinandini Sharma
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Manoj Samant
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | | | | | - Diane R. Yuskin
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - Li Jenny Jin
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | - David G. Parkes
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
| | | | - Soumitra S. Ghosh
- Amylin Pharmaceuticals LLC, San Diego, California, United States of America
- * E-mail:
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22
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Bhavsar S, Mudaliar S, Cherrington A. Evolution of exenatide as a diabetes therapeutic. Curr Diabetes Rev 2013; 9:161-93. [PMID: 23256660 PMCID: PMC3664512 DOI: 10.2174/1573399811309020007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 12/18/2022]
Abstract
Type 2 diabetes (T2DM) is a disease of epidemic proportion associated with significant morbidity and excess mortality. Optimal glucose control reduces the risk of microvascular and possibly macrovascular complications due to diabetes. However, glycemic control is rarely optimal and several therapeutic interventions for the treatment of diabetes cause hypoglycemia and weight gain; some may exacerbate cardiovascular risk. Exenatide (synthetic exendin-4) is a glucagon- like peptide-1 receptor (GLP-1R) agonist developed as a first-in-class diabetes therapy. This review presents an overview of the evolution of exenatide as a T2DM treatment, beginning with the seminal preclinical discoveries and continuing through to clinical pharmacology investigations and phase 3 clinical trials. In patients with T2DM, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, and enhanced satiety. In controlled phase 3 clinical trials ranging from 12 to 52 weeks, 10-mcg exenatide twice daily (ExBID) reduced mean HbA1c by -0.8% to -1.7% as monotherapy or in combination with metformin (MET), sulfonylureas (SFU), and/or thiazolidinediones (TZD); with mean weight losses of -1.2 kg to -8.0 kg. In controlled phase 3 trials ranging from 24 to 30 weeks, a 2-mg once-weekly exenatide formulation (ExQW) reduced mean HbA1c by -1.3% to -1.9%, with mean weight reductions of -2.3 to -3.7 kg. Exenatide was generally well-tolerated. The most common side effects were gastrointestinal in nature, mild, and transient. Nausea was the most prevalent adverse event. The incidence of hypoglycemia was generally low. By building upon early observations exenatide was successfully developed into an effective diabetes therapy.
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Affiliation(s)
- Sunil Bhavsar
- Amylin Pharmaceuticals, Inc., San Diego CA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
| | - Sunder Mudaliar
- VA San Diego Healthcare System and University of California at San Diego, San Diego CA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
| | - Alan Cherrington
- Vanderbilt University, Nashville TN, USA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
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23
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Wu Y, Wang L, Lin C, Lin Y, Zhou M, Chen L, Connolly B, Zhang Y, Chen T, Shaw C. Vasorelaxin: a novel arterial smooth muscle-relaxing eicosapeptide from the skin secretion of the Chinese piebald odorous frog (Odorrana schmackeri). PLoS One 2013; 8:e55739. [PMID: 23405205 PMCID: PMC3566010 DOI: 10.1371/journal.pone.0055739] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 12/29/2012] [Indexed: 11/19/2022] Open
Abstract
The defensive skin secretions of amphibians are a rich resource for the discovery of novel, bioactive peptides. Here we report the identification of a novel vascular smooth muscle-relaxing peptide, named vasorelaxin, from the skin secretion of the Chinese piebald odorous frog, Odorrana schmackeri. Vasorelaxin consists of 20 amino acid residues, SRVVKCSGFRPGSPDSREFC, with a disulfide-bridge between Cys-6 and Cys-20. The structure of its biosynthetic precursor was deduced from cloned skin cDNA and consists of 67 amino acid residues encoding a single copy of vasorelaxin (vasorelaxin, accession number: HE860494). Synthetic vasorelaxin caused a profound relaxation of rat arterial smooth muscle with an EC50 of 6.76 nM.
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Affiliation(s)
- Yuxin Wu
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Lei Wang
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Chen Lin
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Yan Lin
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Mei Zhou
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Liang Chen
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Brian Connolly
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Yingqi Zhang
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
- Tangshan Gongren Hospital, No.27, Wenhua Road, Tangshan City, Hebei Province, China
- * E-mail: (YZ); (CS)
| | - Tianbao Chen
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
| | - Chris Shaw
- Natural Drug Discovery Group, School of Pharmacy, Queen’s University, Belfast, Northern Ireland, United Kingdom
- * E-mail: (YZ); (CS)
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Parkes DG, Mace KF, Trautmann ME. Discovery and development of exenatide: the first antidiabetic agent to leverage the multiple benefits of the incretin hormone, GLP-1. Expert Opin Drug Discov 2012; 8:219-44. [PMID: 23231438 DOI: 10.1517/17460441.2013.741580] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
INTRODUCTION The GLP-1 receptor agonist exenatide is synthetic exendin-4, a peptide originally isolated from the salivary secretions of the Gila monster. Exenatide was developed as a first-in-class diabetes therapy, with immediate- and extended-release formulations. In preclinical diabetes models, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, reduced body weight, enhanced satiety, and preserved pancreatic β-cell function. In clinical trials, both exenatide formulations reduced hyperglycemia in patients with type 2 diabetes mellitus (T2DM) and were associated with weight loss. AREAS COVERED This article reviews the development of exenatide from its discovery and preclinical investigations, to the elucidation of its pharmacological mechanisms of action in mammalian systems. The article also presents the pharmacokinetic profiling and toxicology studies of exenatide, as well as its validation in clinical trials. EXPERT OPINION GLP-1 receptor agonists represent a new paradigm for the treatment of patients with T2DM. By leveraging incretin physiology, a natural regulatory system that coordinates oral nutrient intake with mechanisms of metabolic control, these agents address multiple core defects in the pathophysiology of T2DM. Studies have identified unique benefits including improvements in glycemic control and weight, and the potential for beneficial effects on the cardiometabolic system without the increased risk of hypoglycemia associated with insulin therapy. Peptide hormone therapeutics can offer significant advantages over small molecule drug targets when it comes to specificity, potency, and more predictable side effects. As exemplified by exenatide, injectable peptides can be important drugs for the treatment of chronic diseases, such as T2DM.
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Affiliation(s)
- David G Parkes
- Amylin Pharmaceuticals, Inc., 9360 Towne Centre Drive, San Diego, CA 92121, USA.
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25
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Ma C, Wang H, Wu Y, Zhou M, Lowe G, Wang L, Zhang Y, Chen T, Shaw C. Helokinestatin-7 peptides from the venoms of Heloderma lizards. Peptides 2012; 35:300-5. [PMID: 22504015 DOI: 10.1016/j.peptides.2012.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/12/2012] [Accepted: 03/12/2012] [Indexed: 10/28/2022]
Abstract
Helokinestatins 1-6 constitute a family of bradykinin antagonist peptides originally isolated from the venoms of the Gila Monster, Heloderma suspectum and the Mexican beaded lizard, Heloderma horridum. Here we report the identification, isolation and preliminary pharmacological characterization of two novel tridecapeptides, named helokinestatin-7S (FDDDSTELILEPR - 1550 Da) and helokinestatin-7H (FDDDSRKLILEPR - 1604 Da), whose primary structures were predicted from cDNAs cloned from venom libraries of respective Heloderma lizards. Computed molecular masses of putative helokinestatin-7 peptides were used as tools to locate these peptides in archived LC/MS fractions from respective venoms and sequences were confirmed by MS/MS fragmentation. A synthetic replicate of helokinestatin-7H was found to antagonize the relaxation effect of bradykinin on rat arterial smooth muscle but to have no measurable effects alone. In contrast, synthetic helokinestatin-7S was found to directly contract this preparation. Studies on related natural peptides with subtle differences in primary structure can provide the tools for structure/activity studies in pharmacological investigations directed toward unraveling the molecular basis of venom toxicity and for the evaluation of potential therapeutic leads.
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Affiliation(s)
- Chengbang Ma
- Natural Drug Discovery Group, School of Pharmacy, Queen's University Belfast, Belfast, Northern Ireland, UK
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26
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The development of Byetta (exenatide) from the venom of the Gila monster as an anti-diabetic agent. Toxicon 2012; 59:464-71. [DOI: 10.1016/j.toxicon.2010.12.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Accepted: 12/21/2010] [Indexed: 12/19/2022]
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27
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Irwin DM. Origin and convergent evolution of exendin genes. Gen Comp Endocrinol 2012; 175:27-33. [PMID: 22137915 DOI: 10.1016/j.ygcen.2011.11.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 10/15/2022]
Abstract
Exendins are secretin hormone-like peptides that are components of the toxins from two venomous lizards, Heloderma suspectum (Gila monster) and Heloderma horridium (Mexican bearded lizard). Exendins-1 and -2 are vasoactive intestinal peptide (VIP)-like, both in sequence and function, while exendins-3 and -4 are glucagon-like peptide-1 (GLP-1)-like. The evolutionary origin of these peptides, and the genes that encode them, has been unclear. Recently, genes orthologous to exendin have been identified in reptiles, birds and amphibians. Analysis of the orthologous sequences demonstrates that the Heloderma exendins diversified by gene duplication from a common exendin ancestor on the Heloderma lineage after divergence from other reptiles, including the anole lizard and Burmese python. In addition, the exendin toxin peptide sequences, but not their pro or signal peptides, have evolved very rapidly on the Heloderma lineage, likely as they adapted to their new function as toxins. Exendins-1 and -2 not only evolved rapidly but their sequences have evolved convergently upon that of VIP, resulting in a doubling of its identity with VIP, while exendins-3 and -4 have retained an ancestral property of being more GLP-1-like sequences. These results suggest that the ancestral role of exendin, which is potentially still retained in some species, had greater similarity with proglucagon-derived peptides or GIP.
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Affiliation(s)
- David M Irwin
- Department of Laboratory Medicine and Pathobiology, 1 King's College Circle, University of Toronto, Toronto, Ont, Canada M5S 1A8.
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Wang S, Yu J, Li W, Li F. Structural study of an active analog of EX-4 in solution and micelle associated states. Biopolymers 2011; 96:348-57. [PMID: 21072854 DOI: 10.1002/bip.21566] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Of many drug candidates designed for treatment of type II diabetes, an exendin-4 (EX-4) analog from the substitutions of both beta-Asp for Glu3 and Tyrfor Glnl3 of EX-4 was found to have a prolongation in biological half life, an increase in cell proliferation and a remarkable improvement in reducing blood glucose with respect to EX-4. In this study, we applied CD and NMR approaches to characterize the structures of this active EX-4 analog in water, trifluoroethanol (TFE) aqueous solution, and dodecylphosphocholine (DPC) micelles and compared the results of the EX-4 analog with those of EX-4. Both EX-4 peptides adopt alpha-helix structures with the N-termini disordered and the C-terminal parts folded as hydrophobic clusters in these media. However, the analog has a longer helical extension in the N-terminal part than EX-4. The increasing helical turns may favor affinity for extracellular domain of glucagon-like peptide-1 receptor and accurate positioning of the crucial N-terminal residues in the transmembrane domains of the receptor. The analog has a stronger propensity to aggregate than the native EX-4, which is attributed to more coiled-coil interaction in the analog than in its native type. We also probed the association of EX-4 and its analog to DPC micelles and observed micelle-induced insertion of both peptides with their N- and C-termini as well as the central parts embedded in micelles and the residues near Asp9 and the residues around Trp25-Ser32 more water exposed. A single-step ligand-receptor binding model was suggested based on the analysis of these results.
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Affiliation(s)
- Shuo Wang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
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29
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Akahoshi M, Song CH, Piliponsky AM, Metz M, Guzzetta A, Abrink M, Schlenner SM, Feyerabend TB, Rodewald HR, Pejler G, Tsai M, Galli SJ. Mast cell chymase reduces the toxicity of Gila monster venom, scorpion venom, and vasoactive intestinal polypeptide in mice. J Clin Invest 2011; 121:4180-91. [PMID: 21926462 DOI: 10.1172/jci46139] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 08/03/2011] [Indexed: 12/22/2022] Open
Abstract
Mast cell degranulation is important in the pathogenesis of anaphylaxis and allergic disorders. Many animal venoms contain components that can induce mast cell degranulation, and this has been thought to contribute to the pathology and mortality caused by envenomation. However, we recently reported evidence that mast cells can enhance the resistance of mice to the venoms of certain snakes and that mouse mast cell-derived carboxypeptidase A3 (CPA3) can contribute to this effect. Here, we investigated whether mast cells can enhance resistance to the venom of the Gila monster, a toxic component of that venom (helodermin), and the structurally similar mammalian peptide, vasoactive intestinal polypeptide (VIP). Using 2 types of mast cell-deficient mice, as well as mice selectively lacking CPA3 activity or the chymase mouse mast cell protease-4 (MCPT4), we found that mast cells and MCPT4, which can degrade helodermin, can enhance host resistance to the toxicity of Gila monster venom. Mast cells and MCPT4 also can limit the toxicity associated with high concentrations of VIP and can reduce the morbidity and mortality induced by venoms from 2 species of scorpions. Our findings support the notion that mast cells can enhance innate defense by degradation of diverse animal toxins and that release of MCPT4, in addition to CPA3, can contribute to this mast cell function.
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Affiliation(s)
- Mitsuteru Akahoshi
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305-5324, USA
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30
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Ma C, Yang M, Zhou M, Wu Y, Wang L, Chen T, Ding A, Shaw C. The natriuretic peptide/helokinestatin precursor from Mexican beaded lizard (Heloderma horridum) venom: Amino acid sequence deduced from cloned cDNA and identification of two novel encoded helokinestatins. Peptides 2011; 32:1166-71. [PMID: 21439339 DOI: 10.1016/j.peptides.2011.03.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 03/10/2011] [Accepted: 03/10/2011] [Indexed: 11/19/2022]
Abstract
Natriuretic peptides are common components of reptile venoms and molecular cloning of their biosynthetic precursors has revealed that in snakes, they co-encode bradykinin-potentiating peptides and in venomous lizards, some co-encode bradykinin inhibitory peptides such as the helokinestatins. The common natriuretic peptide/helokinestatin precursor of the Gila Monster, Heloderma suspectum, encodes five helokinestatins of differing primary structures. Here we report the molecular cloning of a natriuretic peptide/helokinestatin precursor cDNA from a venom-derived cDNA library of the Mexican beaded lizard (Heloderma horridum). Deduction of the primary structure of the encoded precursor protein from this cloned cDNA template revealed that it consisted of 196 amino acid residues encoding a single natriuretic peptide and five helokinestatins. While the natriuretic peptide was of identical primary structure to its Gila Monster (H. suspectum) homolog, the encoded helokinestatins were not, with this region of the common precursor displaying some significant differences to its H. suspectum homolog. The helokinestatin-encoding region contained a single copy of helokinestatin-1, 2 copies of helokinestatin-3 and single copies of 2 novel peptides, (Phe)(5)-helokinestatin-2 (VPPAFVPLVPR) and helokinestatin-6 (GPPFNPPPFVDYEPR). All predicted peptides were found in reverse phase HPLC fractions of the same venom. Synthetic replicates of both novel helokinestatins were found to antagonize the relaxing effect of bradykinin on rat tail artery smooth muscle. Thus lizard venom continues to provide a source of novel biologically active peptides.
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Affiliation(s)
- Chengbang Ma
- Molecular Therapeutics Research, School of Pharmacy, Queen's University, Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
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31
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Kwok HF, Ivanyi C, Morris A, Shaw C. Proteomic and Genomic Studies on Lizard Venoms in the Last Decade. PROTEOMICS INSIGHTS 2010. [DOI: 10.4137/pri.s3693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Traditionally man has looked to nature to provide cures for diseases. This approach still exists today in the form of ‘bio-prospecting’ for therapeutically-active compounds in venoms. For example, the venoms of many reptiles offer a spectacular laboratory of bioactive molecules, including peptides and proteins. In the last 10–15 years, there have been a number of major proteomic and genomic research breakthroughs on lizard venoms. In this current review, the key findings from these proteomic and genomic studies will be critically discussed and suggestions will be offered for future focused investigations. It is our intention that this article will not only provide a comprehensive picture of the state of current knowledge of the components of lizard venoms, but also engender awareness in readers of the need to protect and conserve such uniquely precious natural resources for several reasons, including the potential benefit of humankind.
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Affiliation(s)
- Hang Fai Kwok
- Molecular Therapeutics Research, School of Pharmacy, Queen's University Belfast, Northern Ireland BT9 7BL, U.K
| | - Craig Ivanyi
- Arizona-Sonora Desert Museum, 2021 North Kinney Road, Tucson, Arizona 85743 U.S.A
| | - Andrew Morris
- School of Pharmacy, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Malaysia
| | - Chris Shaw
- Molecular Therapeutics Research, School of Pharmacy, Queen's University Belfast, Northern Ireland BT9 7BL, U.K
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32
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Liu B, Dong Q, Wang M, Shi L, Wu Y, Yu X, Shi Y, Shan Y, Jiang C, Zhang X, Gu T, Chen Y, Kong W. Preparation, Characterization, and Pharmacodynamics of Exenatide-Loaded Poly(DL-lactic-co-glycolic acid) Microspheres. Chem Pharm Bull (Tokyo) 2010; 58:1474-9. [DOI: 10.1248/cpb.58.1474] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Bin Liu
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
- State Key Laboratory of Supramolecular Structure and Material, Jilin University
- Jilin Product Quality Supervision Inspection
| | - Qingguang Dong
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Mengshu Wang
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Lin Shi
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Yongge Wu
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
- State Key Laboratory of Supramolecular Structure and Material, Jilin University
| | - Xianghui Yu
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
- State Key Laboratory of Supramolecular Structure and Material, Jilin University
| | - Yanyu Shi
- Jilin Product Quality Supervision Inspection
| | - Yaming Shan
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Chunlai Jiang
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Xizhen Zhang
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Tiejun Gu
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Yan Chen
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
| | - Wei Kong
- The State Engineering Laboratory of AIDS Vaccine, Jilin University
- State Key Laboratory of Supramolecular Structure and Material, Jilin University
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Abstract
The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are essential components in the regulation of blood glucose levels in mammals. These two incretins are produced by evolutionarily related genes and these hormones show similarity in sequence as both are glucagon-like sequences. Genes for these hormones have been identified in a number of diverse vertebrate species indicating that they originated prior to the earliest divergences of vertebrate species. However, analysis of functional and sequence data suggest that each of these hormones acquired incretin activity independently, and only since the divergence of tetrapods from fish. Not only are the hormones related, but so are their receptors. Like the hormones, the incretin action of the receptors is not a product of a shared common ancestral history, as the receptors for GLP-1 and GIP are not most closely related. Further study of the physiological functions of GLP-1 and GIP in additional vertebrates is required to better understand the origin of incretin action.
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Affiliation(s)
- David M Irwin
- Department of Laboratory Medicine and Pathobiology, Banting and Best Diabetes Centre, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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34
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Hellström PM. Glucagon-like peptide-1 gastrointestinal regulatory role in metabolism and motility. VITAMINS AND HORMONES 2010; 84:319-29. [PMID: 21094906 DOI: 10.1016/b978-0-12-381517-0.00012-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Gastrointestinal (GI) motility, primarily gastric emptying, balances the hormonal output that takes place after food intake in order to maintain stable blood sugar. The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), work together to reduce postprandial hyperglycemia by glucose-dependent insulin secretion and inhibition of glucagon release, as well as inhibition of GI motility and gastric emptying. GLP-1 is considered the more effective of the two incretins due to its additional inhibitory effects on GI motility. It is observed that patients on treatment with GLP-1 analogues or exenatide achieve a considerable weight loss during treatment. This is of benefit to improve insulin resistance in type 2 diabetes. Furthermore, weight loss per se is of considerable benefit in an even longer health perspective. The weight loss is considered to be due to the inhibition of GI motility. This effect has been studied in animal experimentation, and from there taken to involve studies on GI motility in healthy volunteers and patients with irritable bowel syndrome (IBS). Evolving to a phase II study in IBS, the GLP-1 analogue (ROSE-010) was recently shown to be effective for treatment of acute pain attacks in IBS. Taken together, data speak in favor of GI motility as a central component not only in metabolic disorders but also in IBS, be it due to a direct relaxing effect on GI smooth muscle or a slow emptying of gastric contents resulting in a less outspoken nutritional demand on hormonal regulatory functions in the GI tract.
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Affiliation(s)
- Per M Hellström
- Department of Medical Sciences, Gastroenterology Unit, Uppsala University Hospital, Uppsala, Sweden
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35
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Verspohl E. Novel therapeutics for type 2 diabetes: Incretin hormone mimetics (glucagon-like peptide-1 receptor agonists) and dipeptidyl peptidase-4 inhibitors. Pharmacol Ther 2009; 124:113-38. [DOI: 10.1016/j.pharmthera.2009.06.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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36
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Bhushan R, Elkind-Hirsch KE, Bhushan M, Butler WJ, Duncan K, Marrioneaux O. Improved glycemic control and reduction of cardiometabolic risk factors in subjects with type 2 diabetes and metabolic syndrome treated with exenatide in a clinical practice setting. Diabetes Technol Ther 2009; 11:353-9. [PMID: 19459763 DOI: 10.1089/dia.2008.0090] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) with the presence of metabolic syndrome (MetS) carries increased risk for cardiovascular disease. Adjunctive exenatide treatment in patients with T2DM is associated with improvements in glycemic control coupled with progressive weight reduction. We evaluated exenatide use on glycosylated hemoglobin A1c (HbA(1c)) and cardiometabolic risk factors in patients with T2DM and MetS in a single clinical practice setting. METHODS A retrospective analysis of clinical data extracted from the records of 176 adult patients with T2DM and MetS (106 women, 70 men) who received exenatide along with existing therapeutic regimes from 2005 to 2007 was performed. HbA(1c), lipid profiles, blood pressure, and anthropometric measures were evaluated at baseline and after 16 (+/-4) weeks of exenatide therapy. RESULTS Mean HbA(1c) was significantly reduced from baseline in 16 weeks (P < 0.001), with 68% of patients achieving HbA(1c) <7%. Total, high-density lipoprotein-, and low-density lipoprotein-cholesterol levels decreased significantly. This decline was not attributable to changes in lipid-lowering agents. Significant reductions were also noted in body mass index, mean body weight, and abdominal girth (AG) with the addition of exenatide. Additional analyses showed 76% of subjects lost weight. Lessening of AG was much more pronounced in female compared with male subjects with diabetes (P < 0.032). No consistent changes in blood pressure were observed. CONCLUSIONS We found that addition of exenatide to an existing treatment regimen in patients with T2DM and MetS resulted in significant reductions in HbA(1c) along with decline in lipids, AG, and body weight. This indicates improvement in these patients' metabolic profiles.
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Affiliation(s)
- Rajat Bhushan
- Metabolic Center of Louisiana Research Foundation, Baton Rouge, Louisiana 70808, USA.
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37
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Prabha L, Govindappa N, Adhikary L, Melarkode R, Sastry K. Identification of the dipeptidyl aminopeptidase responsible for N-terminal clipping of recombinant Exendin-4 precursor expressed in Pichia pastoris. Protein Expr Purif 2009; 64:155-61. [DOI: 10.1016/j.pep.2008.10.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 10/30/2008] [Accepted: 10/30/2008] [Indexed: 11/29/2022]
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38
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Kwok HF, Chen T, Ivanyi C, Shaw C. DNA in Amphibian and Reptile Venom Permits Access to Genomes without Specimen Sacrifice. GENOMICS INSIGHTS 2008. [DOI: 10.4137/gei.s1039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Amphibian defensive skin secretions and reptile venoms are rich sources of bioactive peptides with potential pharmacological/pharmaceutical applications. As amphibian and reptile populations are in rapid global decline, our research group has been developing analytical methods that permit generation of robust molecular data from non-invasive skin secretion samples and venom samples. While previously we have demonstrated that parallel proteome and venom gland transcriptome analyses can be performed on such samples, here we report the presence of DNA that facilitates the more widely-used applications of gene sequencing, such as molecular phylogenetics, in a non-invasive manner that circumvents specimen sacrifice. From this “surrogate” tissue, we acquired partial 12S and 16S rRNA gene sequences that are presented for illustration purposes. Thus from a single sample of amphibian skin secretion and reptile venom, robust and complementary proteome, transcriptome and genome data can be generated for applications in diverse scientific disciplines.
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Affiliation(s)
- Hang Fai Kwok
- Molecular Therapeutics Research, School of Pharmacy, Medical Biology Centre, Queen's University Belfast, BT9 7BL Northern Ireland, U.K
- School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, U.K
| | - Tianbao Chen
- Molecular Therapeutics Research, School of Pharmacy, Medical Biology Centre, Queen's University Belfast, BT9 7BL Northern Ireland, U.K
| | - Craig Ivanyi
- The Arizona-Sonora Desert Museum, Kinney Road, Tucson, Arizona 85743-8918, U.S.A
| | - Chris Shaw
- Molecular Therapeutics Research, School of Pharmacy, Medical Biology Centre, Queen's University Belfast, BT9 7BL Northern Ireland, U.K
- School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, U.K
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39
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Rothkopf MM, Bilof ML, Haverstick LP, Nusbaum MJ. Synergistic weight loss and diabetes resolution with exenatide administration after laparoscopic gastric banding. Surg Obes Relat Dis 2008; 5:128-31. [PMID: 18996762 DOI: 10.1016/j.soard.2008.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 08/15/2008] [Accepted: 09/02/2008] [Indexed: 02/05/2023]
Affiliation(s)
- Michael M Rothkopf
- The Metabolic Medicine & Weight Control Center, Morristown, New Jersey, USA
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40
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Ban K, Noyan-Ashraf MH, Hoefer J, Bolz SS, Drucker DJ, Husain M. Cardioprotective and vasodilatory actions of glucagon-like peptide 1 receptor are mediated through both glucagon-like peptide 1 receptor-dependent and -independent pathways. Circulation 2008; 117:2340-50. [PMID: 18427132 DOI: 10.1161/circulationaha.107.739938] [Citation(s) in RCA: 783] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The glucagon-like peptide 1 receptor (GLP-1R) is believed to mediate glucoregulatory and cardiovascular effects of the incretin hormone GLP-1(7-36) (GLP-1), which is rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to GLP-1(9-36), a truncated metabolite generally thought to be inactive. Novel drugs for the treatment of diabetes include analogues of GLP-1 and inhibitors of DPP-4; however, the cardiovascular effects of distinct GLP-1 peptides have received limited attention. METHODS AND RESULTS Here, we show that endothelium and cardiac and vascular myocytes express a functional GLP-1R as GLP-1 administration increased glucose uptake, cAMP and cGMP release, left ventricular developed pressure, and coronary flow in isolated mouse hearts. GLP-1 also increased functional recovery and cardiomyocyte viability after ischemia-reperfusion injury of isolated hearts and dilated preconstricted arteries from wild-type mice. Unexpectedly, many of these actions of GLP-1 were preserved in Glp1r(-/-) mice. Furthermore, GLP-1(9-36) administration during reperfusion reduced ischemic damage after ischemia-reperfusion and increased cGMP release, vasodilatation, and coronary flow in wild-type and Glp1r(-/-) mice, with modest effects on glucose uptake. Studies using a DPP-4-resistant GLP-1R agonist and inhibitors of DPP-4 and nitric oxide synthase showed that the effects of GLP-1(7-36) were partly mediated by GLP-1(9-36) through a nitric oxide synthase-requiring mechanism that is independent of the known GLP-1R. CONCLUSIONS These data describe cardioprotective actions of GLP-1(7-36) mediated through the known GLP-1R and novel cardiac and vascular actions of GLP-1(7-36) and its metabolite GLP-1(9-36) independent of the known GLP-1R. Our data suggest that the extent to which GLP-1 is metabolized to GLP-1(9-36) may have functional implications in the cardiovascular system.
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Affiliation(s)
- Kiwon Ban
- Heart and Stroke Richard Lewar Centre of Excellence for Cardiovascular Research, University of Toronto, Ontario, Canada M5G-1C4
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41
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Li L. Is Glucagon-like peptide-1, an agent treating diabetes, a new hope for Alzheimer's disease? Neurosci Bull 2007; 23:58-65. [PMID: 17592527 PMCID: PMC5550570 DOI: 10.1007/s12264-007-0009-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) has been endorsed as a promising and attractive agent in the treatment of type 2 diabetes mellitus (T2DM). Both Alzheimer's disease (AD) and T2DM share some common pathophysiologic hallmarks, such as amyloid beta (Abeta), phosphoralation of tau protein, and glycogen synthase kinase-3. GLP-1 possesses neurotropic properties and can reduce amyloid protein levels in the brain. Based on extensive studies during the past decades, the understanding on AD leads us to believe that the primary targets in AD are the Abeta and tau protein. Combine these findings, GLP-1 is probably a promising agent in the therapy of AD. This review was focused on the biochemistry and physiology of GLP-1, communities between T2DM and AD, new progresses of GLP-1 in treating T2MD and improving some pathologic hallmarks of AD.
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Affiliation(s)
- Lin Li
- Gerontology Institute, Shanxi Medical University, Taiyuan 030001, China.
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42
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Scott KA, Moran TH. The GLP-1 agonist exendin-4 reduces food intake in nonhuman primates through changes in meal size. Am J Physiol Regul Integr Comp Physiol 2007; 293:R983-7. [PMID: 17581835 DOI: 10.1152/ajpregu.00323.2007] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exendin-4 (Ex4), a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist, has been shown to reduce food intake and suppress gastric emptying in rodents and humans. In this study we investigated the effects of peripheral administration of Ex4 on food intake and meal patterns in adult male rhesus macaques. Rhesus macaques (n = 4) that had been trained to lever press for food pellets were injected intramuscularly 15 min before the start of their 6-h daily feeding period. Ex4 was given at doses of 0.10, 0.32, 0.56, 1.0, and 3.0 microg/kg. Ex4 suppressed food intake in a dose-dependent manner, with the 3.0 microg/kg dose completely preventing feeding during the 6-h period and the 0.10 microg/kg dose suppressing intake by 17%. Doses of 0.32, 0.56, 1.0, and 3.0 microg/kg caused significant reductions in cumulative intake at all six hourly time points. Ex4 inhibited food intake through a specific effect on meal size. Meal size was significantly reduced in a dose-dependent manner with significant reductions at the 0.32 and 1.0 microg/kg doses (P < 0.05). Day 2 and 3 intakes returned to baseline levels with no compensation for Ex4-induced feeding suppression. Administration of doses of 0.32 and 0.56 microg/kg Ex4 over 5 consecutive days led to sustained reductions in intake with no evidence of compensation. Again, these reductions were due to specific effects on meal size. These results demonstrate that activation of GLP-1 pathways has potent effects on the controls of meal size and overall food intake in a nonhuman primate model.
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Affiliation(s)
- Karen A Scott
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
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43
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Chen J, Bai G, Yang Y, Geng P, Cao Y, Zhu Y. Identifying glucagon-like peptide-1 mimetics using a novel functional reporter gene high-throughput screening assay. Peptides 2007; 28:928-34. [PMID: 17267075 DOI: 10.1016/j.peptides.2006.12.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Revised: 12/04/2006] [Accepted: 12/04/2006] [Indexed: 11/25/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) stimulates insulin and inhibits glucagon secretion and therefore could potentially be used to treat diabetes type II. However, its therapeutic use is limited by its short half-life in vivo, due mainly to enzymatic degradation by dipeptidyl peptidase IV (DPP-IV). Developing GLP-1 analogs with greater bioactivity is therefore an important step toward using them therapeutically. Accordingly, we aimed to identify GLP-1 mimetic peptides by creating a high-throughput screening (HTS) assay of a phage displayed (PhD) peptide library. This assay was functionally based using the GLP-1 receptor (GLP-1R) gene. Rat GLP-1R cDNA was transfected into CHO/enhanced green fluorescent protein (EGFP) cells by lipofection. The resulting stable, recombinant cell line functionally expressed the GLP-1R and a cAMP-responsive EGFP reporter gene, to monitor receptor activation, and was used to screen a PhD dodecapeptide library. After four rounds of selection, 10 positive clones were selected based on functional evaluation and sequenced. Three sequences were obtained, corresponding to three different domains of GLP-1 (Group 1: 22-34; Group 2: 18-29; and Group 3: 6-17). The Group 3 peptide had the highest bioactivity, was synthesized, and designated KS-12. Importantly, KS-12 activated GLP-1R in vitro and reduced blood glucose levels in a dose-dependent manner when administered to Chinese Kunming mice. Although KS-12 was not as effective as GLP-1, it was significantly resistant to DPP-IV both in vitro and in vivo. Thus, this study provides a novel way to screen DPP-IV resistant agonist peptides of GLP-1 from a PhD peptide library using the functional reporter gene HTS assay.
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Affiliation(s)
- Jiaqi Chen
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 30071, China
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44
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Iltz JL, Baker DE, Setter SM, Keith Campbell R. Exenatide: an incretin mimetic for the treatment of type 2 diabetes mellitus. Clin Ther 2006; 28:652-65. [PMID: 16861088 DOI: 10.1016/j.clinthera.2006.05.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2006] [Indexed: 11/16/2022]
Abstract
BACKGROUND Exenatide is a subcutaneously injected incretin mimetic. It is indicated as adjunctive therapy to improve glycemic control in patients with type 2 diabetes mellitus (T2DM) who are already receiving therapy with metformin, a sulfonylurea, or both but continue to have suboptimal glycemic control. OBJECTIVE This article reviews available information on the clinical pharmacology, comparative efficacy, tolerability, drug interactions, contraindications and precautions, dosage and administration, availability and storage, and cost of exenatide. METHODS MEDLINE (1966-April 2006) and Web of Science (1995-April 2006) were searched for original research and review articles published in the English language. The search terms used were exenatide, exendin-4, glucagon-Like peptide-1, GLP-1, and incretin mimetic. The reference lists of identified articles were also consulted, as was selected information from the package insert for exenatide. All relevant comparative efficacy studies that were available in published form were included in the review. RESULTS Naturally occurring incretins, such as glucagon-like peptide-1 (GLP-1), exhibit insulinotropic properties after release into the circulation from the gut. As a GLP-1 agonist, exenatide improves glucose homeostasis by mimicking the actions of naturally occurring GLP-1. It improves glycemic control by reducing fasting and postprandial glucose concentrations through a combination of known mechanisms, including glucose-dependent insulin secretion, restoration of first-phase insulin response, regulation of glucagon secretion, delaying gastric emptying, and decreasing food intake. Three Phase III comparative efficacy trials were identified that enrolled a total of 1,446 patients who received exenatide 5 pg SC BID, exenatide 10 mug SC BID, or placebo for 30 weeks in addition to their existing therapy with metformin, sulfonylurea, or both. In these trials, the addition of exenatide was associated with significant reductions in glycosylated hemoglobin (HbA(1c)) values (P < 0.001-P < 0.002), greater proportions of patients achieving an HbA(1c) <or=7%, significant decreases in fasting plasma glucose concentrations (P < 0.001-P < 0.005), and a dose-dependent progressive weight loss compared with placebo. Nausea (43.5%) was the most commonly reported adverse event in the combined exenatide groups. Other adverse events occurring in >10% of patients receiving exenatide were hypoglycemia (19.6%), diarrhea (12.8%), and vomiting (12.8%). CONCLUSIONS During clinical trials, exenatide added to existing metformin and/or sulfonylurea therapy in patients with T2DM reduced fasting and postprandial glucose concentrations, with improvements in HbA(1c) and modest weight loss. The main adverse effect associated with exenatide therapy was nausea.
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Affiliation(s)
- Jason L Iltz
- Department of Pharmacotherapy, College of Pharmacy, Washington State University, Spokane, 99210-1495, USA.
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Chen T, Kwok H, Ivanyi C, Shaw C. Isolation and cloning of exendin precursor cDNAs from single samples of venom from the Mexican beaded lizard (Heloderma horridum) and the Gila monster (Heloderma suspectum). Toxicon 2006; 47:288-95. [PMID: 16386282 DOI: 10.1016/j.toxicon.2005.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 11/03/2005] [Accepted: 11/04/2005] [Indexed: 11/25/2022]
Abstract
Reptile venoms are complex cocktails of bioactive molecules, including peptides. While the drug discovery potential of most species remains unrealized, many are endangered and afforded protection under international treaties. In this study, we describe how potential clinically important bioactive peptides and their corresponding mRNAs can be structurally characterized from single, small samples of reptile venom. The potential type-2 diabetes therapeutics, exendin-3 and exendin-4, from the Mexican beaded lizard (Heloderma horridum) and the Gila monster (Heloderma suspectum), respectively, have been characterized at both protein and nucleic acid levels to illustrate the efficacy of the technique and its contribution to biodiversity conservation.
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Affiliation(s)
- Tianbao Chen
- School of Pharmacy, Queen's University, 97 Lisburn Road, Belfast BT9 7BL, UK
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Beinborn M, Worrall CI, McBride EW, Kopin AS. A human glucagon-like peptide-1 receptor polymorphism results in reduced agonist responsiveness. ACTA ACUST UNITED AC 2005; 130:1-6. [PMID: 15975668 DOI: 10.1016/j.regpep.2005.05.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 04/27/2005] [Accepted: 05/03/2005] [Indexed: 11/18/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) and its cognate receptor play an important physiological role in maintaining blood glucose homeostasis. A GLP-1 receptor (GLP-1R) polymorphism in which threonine 149 is substituted with a methionine residue has been recently identified in a patient with type 2 diabetes but was not found in non-diabetic control subjects. We have functionally assessed the recombinant GLP-1R variant after transient expression in COS-7 and HEK 293 cells. Compared to the wild type receptor, the variant GLP-1R showed (i) similar expression levels, (ii) 60-and 5-fold reduced binding affinities, respectively, for two GLP-1R full agonists, GLP-1 and exendin-4, and (iii) markedly decreased potencies of these peptides in triggering cAMP-mediated signaling (despite conserved efficacies). In contrast to full agonists, the efficacy of the primary GLP-1 metabolite/GLP-1R partial agonist, GLP-1 (9-36) amide, was essentially abolished by the T149M substitution. By hydropathy analysis, the polymorphism localizes to transmembrane domain 1, suggesting this receptor segment as a novel determinant of agonist affinity/efficacy. These findings reveal that naturally occurring sequence variability of the GLP-1R within the human population can result in substantial loss-of-function. A genetic link between the T149M variant and increased susceptibility to type 2 diabetes remains to be established.
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Affiliation(s)
- Martin Beinborn
- Molecular Pharmacology Research Center, Molecular Cardiology Research Institute, Tufts-New England Medical Center, Mailbox 7703, 750 Washington Street, Boston, MA 02111, USA.
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Hui H, Zhao X, Perfetti R. Structure and function studies of glucagon-like peptide-1 (GLP-1): the designing of a novel pharmacological agent for the treatment of diabetes. Diabetes Metab Res Rev 2005; 21:313-31. [PMID: 15852457 DOI: 10.1002/dmrr.553] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is a proglucagon-derived peptide secreted from gut endocrine cells in response to nutrient ingestion. The multifaceted actions of GLP-1 include the following: (1) the stimulation of insulin secretion and of its gene expression, (2) the inhibition of glucagon secretion, (3) the inhibition of food intake, (4) the proliferation and differentiation of beta cells, and (5) the protection of beta-cells from apoptosis. The therapeutic utility of the native GLP-1 molecule is limited by its rapid enzymatic degradation by a serine protease termed dipeptidyl peptidase-IV (DPP-IV). The present article reviews the research studies aimed at elucidating the biosynthesis, metabolism, and molecular characteristics of GLP-1 since it is from these studies that the development of a GLP-1-like pharmacological agent may be derived.
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Affiliation(s)
- Hongxiang Hui
- Division of Endocrinology and Metabolism, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA
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Nielsen LL, Young AA, Parkes DG. Pharmacology of exenatide (synthetic exendin-4) for the treatment of type 2 diabetes. ACTA ACUST UNITED AC 2003; 117:77-88. [PMID: 14700743 DOI: 10.1016/j.regpep.2003.10.028] [Citation(s) in RCA: 357] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
New therapies for the long-term treatment of type 2 diabetes are needed to ameliorate declining pancreatic beta-cell function. Ideally, these therapies should lower fasting and post-prandial blood glucose, produce no hypoglycemia or weight gain, cause no other limiting side effects, and reduce cardiovascular complications. Exenatide (synthetic exendin-4) is a potential therapeutic which may fulfill these criteria. Dose-ranging studies have identified an optimal dose of 0.05 to 0.2 microgram/kg administered subcutaneously twice daily. Pharmacokinetic data support a pivotal study design which mitigates the transient nausea observed in early studies by including a dose initiation period of 1 month at 5 micrograms twice daily, followed by maintenance therapy at 10 micrograms twice daily. Ongoing studies suggest exenatide improves glycemic control through a combination of mechanisms discussed in this review.
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Affiliation(s)
- Loretta L Nielsen
- Amylin Pharmaceuticals Inc., 9360 Town Centre Dr. Ste 110, San Diego, CA 92121, USA.
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Hinke SA, Manhart S, Pamir N, Demuth H, W Gelling R, Pederson RA, McIntosh CH. Identification of a bioactive domain in the amino-terminus of glucose-dependent insulinotropic polypeptide (GIP). BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1547:143-55. [PMID: 11343800 DOI: 10.1016/s0167-4838(01)00181-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The incretins are a class of hormones released from the small bowel that act on the endocrine pancreas to potentiate insulin secretion in a glucose-dependent manner. Due to the requirement for an elevated glucose concentration for activity, the incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1, have potential in the treatment of non-insulin-dependent diabetes mellitus. A series of synthetic peptide GIP fragments was generated for the purpose of elucidating the bioactive domain of the molecule. Peptides were screened for stimulation of cyclic AMP (cAMP) accumulation in Chinese hamster ovary cells transfected with the rat islet GIP receptor. Of the GIP fragments tested, GIP(1-14) and GIP(19-30) demonstrated the greatest cAMP-stimulating ability over the range of concentrations tested (up to 20 microM). In contrast, GIP fragments corresponding to amino acids 15-42, 15-30, 16-30 and 17-30 all demonstrated weak antagonism of GIP(1-42) activity. Competitive-binding displacement studies indicated that these peptides were low-affinity ligands for the GIP receptor. To examine biological activity in vivo, a bioassay was developed in the anesthetized rat. Intravenous infusion of GIP(1-42) (1 pmol/min/100 g) with a concurrent intraperitoneal glucose load (1 g/kg) significantly reduced circulating blood glucose excursions through stimulation of insulin release. Higher doses of GIP(1-14) and GIP(19-30) (100 pmol/min/100 g) also reduced blood glucose excursions.
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Affiliation(s)
- S A Hinke
- Department of Physiology, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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Baggio L, Adatia F, Bock T, Brubaker PL, Drucker DJ. Sustained expression of exendin-4 does not perturb glucose homeostasis, beta-cell mass, or food intake in metallothionein-preproexendin transgenic mice. J Biol Chem 2000; 275:34471-7. [PMID: 10952981 DOI: 10.1074/jbc.m005119200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of glucagon-like peptide (GLP)-1 receptor signaling promotes glucose lowering via multiple mechanisms, including regulation of food intake, glucose-dependent insulin secretion, and stimulation of beta-cell mass. As GLP-1 exhibits a short t(12) in vivo, the biological consequences of prolonged GLP-1 receptor signaling remains unclear. To address this question, we have now generated metallothionein promoter-preproexendin (MT-Ex) transgenic mice. MT-Ex mice process preproexendin correctly, as is made evident by detection of circulating plasma exendin-4 immunoreactivity using high pressure liquid chromatography and an exendin-4-specific radioimmunoassay. Despite elevated levels of exendin-4, fasting plasma glucose and glucose clearance following oral and intraperitoneal glucose tolerance tests are normal in MT-Ex mice. Induction of transgene expression significantly reduced glycemic excursion during both oral and intraperitoneal glucose tolerance tests (p < 0.05) and increased levels of glucose-stimulated insulin following oral glucose administration (p < 0.05). Despite evidence that exendin-4 may induce beta-cell proliferation, beta-cell mass and islet histology were normal in MT-Ex mice. MT-Ex mice exhibited no differences in basal food intake or body weight; however, induction of exendin-4 expression was associated with reduced short term food ingestion (p < 0.05). In contrast, short term water intake was significantly reduced in the absence of zinc in fluid-restricted MT-Ex mice (p < 0.05). These findings illustrate that sustained elevation of circulating exendin-4 is not invariably associated with changes in glucose homeostasis, increased beta-cell mass, or reduction in food intake in mice in vivo.
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Affiliation(s)
- L Baggio
- Department of Laboratory Medicine and Pathobiology, Toronto General Hospital, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario M5G 2C4
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