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Conlon JM, Owolabi BO, Flatt PR, Abdel-Wahab YHA. Amphibian host-defense peptides with potential for Type 2 diabetes therapy - an updated review. Peptides 2024; 175:171180. [PMID: 38401671 DOI: 10.1016/j.peptides.2024.171180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 02/26/2024]
Abstract
Investigations conducted since 2018 have identified several host-defense peptides present in frog skin secretions whose properties suggest the possibility of their development into a new class of agent for Type 2 diabetes (T2D) therapy. Studies in vitro have described peptides that (a) stimulate insulin release from BRIN-BD11 clonal β-cells and isolated mouse islets, (b) display β-cell proliferative activity and protect against cytokine-mediated apoptosis and (c) stimulate production of the anti-inflammatory cytokine IL-10 and inhibit production of the pro-inflammatory cytokines TNF-α and IL-1β. Rhinophrynin-27, phylloseptin-3.2TR and temporin F are peptides with therapeutic potential. Studies in vivo carried out in db/db and high fat-fed mice have shown that twice-daily administration of [S4K]CPF-AM1 and [A14K]PGLa-AM1, analogs of peptides first isolated from the octoploid frog Xenopus amieti, over 28 days lowers circulating glucose and HbA1c concentrations, increases insulin sensitivity and improves glucose tolerance and lipid profile. Peptide treatment produced potentially beneficial changes in the expression of skeletal muscle genes involved in insulin signaling and islet genes involved in insulin secretion in these murine models of T2D. Lead compounds uncovered by the study of frog HDPs may provide a basis for the design of new types of agents that can be used, alone or in combination with existing therapies, for the treatment of T2D.
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Affiliation(s)
- J Michael Conlon
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland BT52 1SA, UK.
| | - Bosede O Owolabi
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland BT52 1SA, UK
| | - Peter R Flatt
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland BT52 1SA, UK
| | - Yasser H A Abdel-Wahab
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland BT52 1SA, UK
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Cayli S, Alimogullari E, Piskin I, Bilginoglu A, Nakkas H. Effect of pioglitazone on the expression of ubiquitin proteasome system and autophagic proteins in rat pancreas with metabolic syndrome. J Mol Histol 2021; 52:929-942. [PMID: 34410563 DOI: 10.1007/s10735-021-10013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 08/10/2021] [Indexed: 11/28/2022]
Abstract
The metabolic syndrome (MetS) and pathologies associated with metabolic dysregulations a worldwide growing problem. Our previous study demonstrated that pioglitazone (PGZ) has beneficial effects on metabolic syndrome associated disturbances in the heart. However, mechanism mediating the molecular alterations of Ubiquitin proteasome system (UPS) and autophagy has not been investigated in rat pancreas with metabolic syndrome. For this reason, we first aimed to detect whether MetS effects on the expression of UPS (p97/VCP, SVIP, Ubiquitin) and autophagic (p62, LC3) proteins in rat pancreas. The second aim of the study was to find impact of pioglitazone on the expression of UPS and autophagic proteins in MetS rat pancreas. To answer these questions, metabolic syndrome induced rats were used as a model and treated with pioglitazone for 2 weeks. Pancreatic tissue injuries, fibrosis and lipid accumulation were evaluated histopathologically in control, MetS and MetS-PGZ groups. Apoptosis and cell proliferation of pancreatic islet cells were assessed in all groups. UPS and autophagic protein expressions of pancreas in all groups were detected by using immunohistochemistry, double-immunfluorescence and Western blotting. Compared with the controls, the rat fed with high sucrose exhibited signs of metabolic syndrome, such as higher body weight, insulin resistance, higher triglyceride level and hyperglycaemia. MetS rats showed pancreatic tissue degeneration, fibrosis and lipid accumulation when their pancreas were examined with Hematoxilen-eozin and Mallory trichrome staining. Metabolic, histopathologic parameters and cell proliferation showed greater improvement in MetS-PGZ rats and pioglitazone decreased apoptosis of islet cells. Moreover, SVIP, ubiquitin, LC3 and p62 expressions were significantly increased while only p97/VCP expression was significantly decreased in MetS-rat pancreas compared to control. PGZ treatment significantly decreased the MetS-induced increases in autophagy markers. Additionally, UPS and autophagy markers were found to colocalizated with insulin and glucagon. Colocalization ratio of UPS markers with insulin showed significant decrease in MetS rats and PGZ increased this ratio, whereas LC3-insulin colocalization displayed significant increase in MetS rats and PGZ reversed this effect. In conclusion, PGZ improved the pancreatic tissue degeneration by increasing the level of p97/VCP and decreasing autophagic proteins, SVIP and ubiquitin expressions in MetS-rats. Moreover, PGZ has an effect on the colocalization ratio of UPS and autophagy markers with insulin.
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Affiliation(s)
- Sevil Cayli
- Department of Histology and Embryology, Medical Faculty, Ankara Yıldırım Beyazıt University, 06800, Ankara, Turkey.
| | - Ebru Alimogullari
- Department of Histology and Embryology, Medical Faculty, Ankara Yıldırım Beyazıt University, 06800, Ankara, Turkey
| | - Ilkay Piskin
- Department of Histology and Embryology, Medical Faculty, Ankara Yıldırım Beyazıt University, 06800, Ankara, Turkey
| | - Ayca Bilginoglu
- Department of Biophysics, Medical Faculty, Ankara Yıldırım Beyazıt University, Ankara, Turkey
| | - Hilal Nakkas
- Department of Histology and Embryology, Medical Faculty, Ankara Yıldırım Beyazıt University, 06800, Ankara, Turkey
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Ansari P, Flatt PR, Harriott P, Hannan JMA, Abdel-Wahab YHA. Identification of Multiple Pancreatic and Extra-Pancreatic Pathways Underlying the Glucose-Lowering Actions of Acacia arabica Bark in Type-2 Diabetes and Isolation of Active Phytoconstituents. PLANTS (BASEL, SWITZERLAND) 2021; 10:1190. [PMID: 34208010 PMCID: PMC8230611 DOI: 10.3390/plants10061190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 12/20/2022]
Abstract
Acacia arabica is used traditionally to treat a variety of ailments, including diabetes. This study elucidated the antidiabetic actions of A. arabica bark together with the isolation of bioactive molecules. Insulin secretion and signal transduction were measured using clonal β cells and mouse islets. Glucose uptake was assessed using 3T3-L1 adipocytes, and in vitro systems assessed additional glucose-lowering actions. High-fat-fed (HFF) obese rats were used for in vivo evaluation, and phytoconstituents were isolated and characterised by RP-HPLC followed by LC-MS and NMR. Hot-water extract of A. arabica (HWAA) increased insulin release from clonal β cells and mouse islets by 1.3-6.8-fold and 1.6-3.2-fold, respectively. Diazoxide, verapamil and calcium-free conditions decreased insulin-secretory activity by 30-42%. In contrast, isobutylmethylxanthine (IBMX), tolbutamide and 30 mM KCl potentiated the insulin-secretory effects. The mechanism of actions of HWAA involved membrane depolarisation and elevation of intracellular Ca2+ together with an increase in glucose uptake by 3T3-L1 adipocytes, inhibition of starch digestion, glucose diffusion, dipeptidyl peptidase-IV (DPP-IV) enzyme activity and protein glycation. Acute HWAA administration (250 mg/5 mL/kg) enhanced glucose tolerance and plasma insulin in HFF obese rats. Administration of HWAA (250 mg/5 mL/kg) for 9 days improved glucose homeostasis and β-cell functions, thereby improving glycaemic control, and circulating insulin. Isolated phytoconstituents, including quercetin and kaempferol, increased insulin secretion in vitro and improved glucose tolerance. The results indicate that HWAA has the potential to treat type 2 diabetes as a dietary supplement or as a source of antidiabetic agents, including quercetin and kaempferol.
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Affiliation(s)
- Prawej Ansari
- School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, UK; (P.R.F.); (P.H.); (Y.H.A.A.-W.)
- Department of Pharmacy, Independent University, Dhaka 1229, Bangladesh;
| | - Peter R. Flatt
- School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, UK; (P.R.F.); (P.H.); (Y.H.A.A.-W.)
| | - Patrick Harriott
- School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, UK; (P.R.F.); (P.H.); (Y.H.A.A.-W.)
| | - J. M. A. Hannan
- Department of Pharmacy, Independent University, Dhaka 1229, Bangladesh;
| | - Yasser H. A. Abdel-Wahab
- School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, UK; (P.R.F.); (P.H.); (Y.H.A.A.-W.)
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Musale V, Moffett RC, Conlon JM, Flatt PR, Abdel-Wahab YH. Beneficial actions of the [A14K] analog of the frog skin peptide PGLa-AM1 in mice with obesity and degenerative diabetes: A mechanistic study. Peptides 2021; 136:170472. [PMID: 33338546 DOI: 10.1016/j.peptides.2020.170472] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/15/2022]
Abstract
The antidiabetic actions of [A14K]PGLa-AM1, an analog of peptide glycine-leucine-amide-AM1 isolated from skin secretions of the octoploid frog Xenopus amieti, were investigated in genetically diabetic-obese db/db mice. Twice daily administration of [A14K]PGLa-AM1 (75 nmol/kg body weight) for 28 days significantly (P < 0.05) decreased circulating blood glucose and HbA1c and increased plasma insulin concentrations leading to improvements in glucose tolerance. The elevated levels of triglycerides, LDL and cholesterol associated with the db/db phenotype were significantly reduced by peptide administration. Elevated plasma alanine transaminase, aspartic acid transaminase, and alkaline phosphatase activities and creatinine concentrations were also significantly decreased. Peptide treatment increased pancreatic insulin content and improved the responses of isolated islets to established insulin secretagogues. No significant changes in islet β-cell and α-cell areas were observed in [A14K]PGLa-AM1 treated mice but the loss of large and medium-size islets was prevented. Peptide administration resulted in a significant (P < 0.01) increase in islet expression of the gene encoding Pdx-1, a major transcription factor in islet cells determining β-cell survival and function, resulting in increased expression of genes involved with insulin secretion (Abcc8, Kcnj11, Slc2a2, Cacn1c) together with the genes encoding the incretin receptors Glp1r and Gipr. In addition, the elevated expression of insulin signalling genes (Slc2a4, Insr, Irs1, Akt1, Pik3ca, Ppm1b) in skeletal muscle associated with the db/db phenotype was downregulated by peptide treatment These data suggest that the anti-diabetic properties of [A14K]PGLa-AM1 are mediated by molecular changes that enhance both the secretion and action of insulin.
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Affiliation(s)
- Vishal Musale
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland, BT52 1SA, UK
| | - R Charlotte Moffett
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland, BT52 1SA, UK
| | - J Michael Conlon
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland, BT52 1SA, UK.
| | - Peter R Flatt
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Yasser H Abdel-Wahab
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland, BT52 1SA, UK
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Anti-hyperglycaemic and insulin-releasing effects of Camellia sinensis leaves and isolation and characterisation of active compounds. Br J Nutr 2020; 126:1149-1163. [PMID: 33331251 DOI: 10.1017/s0007114520005085] [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] [Indexed: 01/21/2023]
Abstract
Anti-diabetic actions of Camellia sinensis leaves, used traditionally for type 2 diabetes (T2DM) treatment, have been determined. Insulin release, membrane potential and intra-cellular Ca were studied using the pancreatic β-cell line, BRIN-BD11 and primary mouse pancreatic islets. Cellular glucose-uptake/insulin action by 3T3-L1 adipocytes, starch digestion, glucose diffusion, dipeptidyl peptidase-4 (DPP-IV) activity and glycation were determined together with in vivo studies assessing glucose homoeostasis in high-fat-fed (HFF) rats. Active phytoconstituents with insulinotropic activity were isolated using reversed-phase HPLC, LCMS and NMR. A hot water extract of C. sinensis increased insulin secretion in a concentration-dependent manner. Insulinotropic effects were significantly reduced by diazoxide, verapamil and under Ca-free conditions, being associated with membrane depolarisation and increased intra-cellular Ca2+. Insulin-releasing effects were observed in the presence of KCl, tolbutamide and isobutylmethylxanthine, indicating actions beyond K+ and Ca2+ channels. The extract also increased glucose uptake/insulin action in 3T3L1 adipocyte cells and inhibited protein glycation, DPP-IV enzyme activity, starch digestion and glucose diffusion. Oral administration of the extract enhanced glucose tolerance and insulin release in HFF rats. Extended treatment (250 mg/5 ml per kg orally) for 9 d led to improvements of body weight, energy intake, plasma and pancreatic insulin, and corrections of both islet size and β-cell mass. These effects were accompanied by lower glycaemia and significant reduction of plasma DPP-IV activity. Compounds isolated by HPLC/LCMS, isoquercitrin and rutin (464·2 Da and 610·3 Da), stimulated insulin release and improved glucose tolerance. These data indicate that C. sinensis leaves warrant further evaluation as an effective adjunctive therapy for T2DM and source of bioactive compounds.
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Ansari P, Flatt PR, Harriott P, Abdel-Wahab YH. Evaluation of the Antidiabetic and Insulin Releasing Effects of A. squamosa, Including Isolation and Characterization of Active Phytochemicals. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1348. [PMID: 33053901 PMCID: PMC7601933 DOI: 10.3390/plants9101348] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022]
Abstract
Annona squamosa is generally referred to as a 'custard apple'. Antidiabetic actions of hot water extract of Annona squamosa (HWAS) leaves together with isolation of active insulinotropic compounds were studied. Insulin release, membrane potential and intracellular Ca2+ were determined using BRIN-BD11 cells and isolated mouse islets. 3T3L1 adipocytes and in vitro models were used to determine cellular glucose uptake, insulin action, starch digestion, glucose diffusion, DPP-IV activity and glycation. Glucose intolerant high-fat fed rats were used for in vivo studies. Active compounds were isolated and characterized by HPLC, LCMS and NMR. HWAS stimulated insulin release from clonal β-cells and mouse islets. Using fluorescent indicator dyes and modulators of insulin secretion, effects could be attributed to depolarization of β-cells and influx of Ca2+. Secretion was stimulated by isobutylmethylxanthine (IBMX), tolbutamide or 30 mM KCl, indicating additional non-KATP dependent pathways. Extract stimulated cellular glucose uptake and insulin action and inhibited starch digestion, protein glycation, DPP-IV enzyme activity and glucose diffusion. Oral HWAS improved glucose tolerance and plasma insulin in high-fat fed obese rats. Treatment for 9 days with HWAS (250 mg/5 mL/kg), partially normalised energy intake, body weight, pancreatic insulin content, and both islet size and beta cell mass. This was associated with improved oral glucose tolerance, increased plasma insulin and inhibition of plasma DPP-IV activity. Isolated insulinotropic compounds, including rutin (C27H30O16), recapitulated the positive actions of HWAS on beta cells and in vivo glucose tolerance and plasma insulin responses. Annona squamosa is attractive as a dietary adjunct in treatment of T2DM and as a source of potential antidiabetic agents including rutin.
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Affiliation(s)
- Prawej Ansari
- School of Biomedical Sciences, Ulster University, Co. Londonderry, Coleraine BT52 1SA, NI, UK; (P.R.F.); (P.H.); (Y.H.A.A.-W.)
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Raaymakers C, Stijlemans B, Martin C, Zaman S, Ballet S, Martel A, Pasmans F, Roelants K. A New Family of Diverse Skin Peptides from the Microhylid Frog Genus Phrynomantis. Molecules 2020; 25:E912. [PMID: 32085597 PMCID: PMC7070584 DOI: 10.3390/molecules25040912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 01/10/2023] Open
Abstract
A wide range of frogs produce skin poisons composed of bioactive peptides for defence against pathogens, parasites and predators. While several frog families have been thoroughly screened for skin-secreted peptides, others, like the Microhylidae, have remained mostly unexplored. Previous studies of microhylids found no evidence of peptide secretion, suggesting that this defence adaptation was evolutionarily lost. We conducted transcriptome analyses of the skins of Phrynomantis bifasciatus and Phrynomantis microps, two African microhylid species long suspected to be poisonous. Our analyses reveal 17 evolutionary related transcripts that diversified from to those of cytolytic peptides found in other frog families. The 19 peptides predicted to be processed from these transcripts, named phrynomantins, show a striking structural diversity that is distinct from any previously identified frog skin peptide. Functional analyses of five phrynomantins confirm the loss of a cytolytic function and the absence of insecticidal or proinflammatory activity, suggesting that they represent an evolutionary transition to a new, yet unknown function. Our study shows that peptides have been retained in the defence poison of at least one microhylid lineage and encourages research on similarly understudied taxa to further elucidate the diversity and evolution of skin defence molecules.
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Affiliation(s)
- Constantijn Raaymakers
- Amphibian Evolution Lab, Biology Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium; (C.R.); (S.Z.)
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; (A.M.); (F.P.)
| | - Benoit Stijlemans
- Unit of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium;
- Myeloid Cell Immunology Lab, VIB Centre for Inflammation Research, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium
| | - Charlotte Martin
- Research Group of Organic Chemistry, Department of Chemistry and Department of Bio-engineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium; (C.M.); (S.B.)
| | - Shabnam Zaman
- Amphibian Evolution Lab, Biology Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium; (C.R.); (S.Z.)
| | - Steven Ballet
- Research Group of Organic Chemistry, Department of Chemistry and Department of Bio-engineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium; (C.M.); (S.B.)
| | - An Martel
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; (A.M.); (F.P.)
| | - Frank Pasmans
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; (A.M.); (F.P.)
| | - Kim Roelants
- Amphibian Evolution Lab, Biology Department, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium; (C.R.); (S.Z.)
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Conlon JM, Mechkarska M, Leprince J. Peptidomic analysis in the discovery of therapeutically valuable peptides in amphibian skin secretions. Expert Rev Proteomics 2019; 16:897-908. [DOI: 10.1080/14789450.2019.1693894] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- J. Michael Conlon
- School of Biomedical Sciences, Ulster University, Coleraine, United Kingdom of Great Britain and Northern Ireland
| | - Milena Mechkarska
- Department of Life Sciences, University of the West Indies at Saint Augustine, Saint Augustine, Trinidad and Tobago
| | - Jérôme Leprince
- Equipe Facteurs Neurotrophiques et Différenciation Neuronale, Universite de Rouen, Mont-Saint-Aignan, France
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Conlon JM, Mechkarska M, Abdel-Wahab YH, Flatt PR. Peptides from frog skin with potential for development into agents for Type 2 diabetes therapy. Peptides 2018; 100:275-281. [PMID: 28887047 DOI: 10.1016/j.peptides.2017.09.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/31/2017] [Accepted: 09/02/2017] [Indexed: 12/12/2022]
Abstract
Several frog skin peptides, first identified as result of their antimicrobial or immunomodulatory activities, have subsequently been shown to stimulate insulin release both in vitro and in vivo and so show potential for development into incretin-based drugs for treatment of patients with Type 2 diabetes mellitus. However, their therapeutic potential as anti-diabetic agents is not confined to this activity as certain frog skin-derived peptides, such as magainin-AM2 and CPF-SE1 and analogs of hymenochirin-1B, tigerinin-1R, and esculentin-2CHa, have been shown to increase insulin sensitivity, promote β-cell proliferation, suppress pancreatic and circulating glucagon concentrations, improve the lipid profile, and selectively alter expression of genes involved in insulin secretion and action in mice with diet-induced obesity, insulin resistance and impaired glucose tolerance. This review assesses the therapeutic possibilities of peptides from frogs belonging to the Pipidae, Dicroglossidae, and Ranidae families, focusing upon work that has been carried out since 2014.
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Affiliation(s)
- J Michael Conlon
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
| | - Milena Mechkarska
- Department of Life Sciences, The University of the West Indies, St Augustine, Trinidad and Tobago
| | - Yasser H Abdel-Wahab
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
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Conlon JM, Moffett RC, Leprince J, Flatt PR. Identification of Components in Frog Skin Secretions with Therapeutic Potential as Antidiabetic Agents. Methods Mol Biol 2018; 1719:319-333. [PMID: 29476521 DOI: 10.1007/978-1-4939-7537-2_21] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Several peptides that were first identified on the basis of their antimicrobial or immunomodulatory properties have subsequently shown potential for development into agents for the treatment of patients with Type 2 diabetes. A strategy is presented for the isolation and characterization of such peptides in norepinephrine-stimulated skin secretions from a range of frog species. The methodology involves fractionation of the secretions by reversed-phase HPLC, identification of fractions containing components that stimulate the rate of release of insulin from BRIN-BD11 clonal β-cells without simultaneously stimulating the release of lactate dehydrogenase, identification of active peptides in the mass range 1-6 kDa by MALDI-TOF mass spectrometry, purification of the peptides to near homogeneity by further HPLC, and structural characterization by automated Edman degradation. The effect of synthetic replicates of the active peptides on glucose homeostasis in vivo may be evaluated in mice fed a high fat diet to produce obesity, glucose intolerance, and insulin resistance.
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Affiliation(s)
- J Michael Conlon
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK.
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK
| | | | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK
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Vasu S, Ojo OO, Moffett RC, Conlon JM, Flatt PR, Abdel-Wahab YHA. Anti-diabetic actions of esculentin-2CHa(1–30) and its stable analogues in a diet-induced model of obesity-diabetes. Amino Acids 2017; 49:1705-1717. [DOI: 10.1007/s00726-017-2469-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 07/19/2017] [Indexed: 12/16/2022]
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Owolabi BO, Ojo OO, Srinivasan DK, Conlon JM, Flatt PR, Abdel-Wahab YHA. Glucoregulatory, endocrine and morphological effects of [P5K]hymenochirin-1B in mice with diet-induced glucose intolerance and insulin resistance. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:769-81. [DOI: 10.1007/s00210-016-1243-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/04/2016] [Indexed: 12/25/2022]
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Manzo G, Scorciapino MA, Srinivasan D, Attoub S, Mangoni ML, Rinaldi AC, Casu M, Flatt PR, Conlon JM. Conformational Analysis of the Host-Defense Peptides Pseudhymenochirin-1Pb and -2Pa and Design of Analogues with Insulin-Releasing Activities and Reduced Toxicities. JOURNAL OF NATURAL PRODUCTS 2015; 78:3041-3048. [PMID: 26606380 DOI: 10.1021/acs.jnatprod.5b00843] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Pseudhymenochirin-1Pb (Ps-1Pb; IKIPSFFRNILKKVGKEAVSLIAGALKQS) and pseudhymenochirin-2Pa (Ps-2Pa; GIFPIFAKLLGKVIKVASSLISKGRTE) are amphibian peptides with broad spectrum antimicrobial activities and cytotoxicity against mammalian cells. In the membrane-mimetic solvent 50% (v/v) trifluoroethanol-H2O, both peptides adopt a well-defined α-helical conformation that extends over almost all the sequence and incorporates a flexible bend. Both peptides significantly (p < 0.05) stimulate the rate of release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥ 0.1 nM but produce loss of integrity of the plasma membrane at concentrations ≥ 1 μM. Increasing cationicity by the substitution Glu(17) → l-Lys in Ps-1Pb and Glu(27) → l-Lys in Ps-2Pa generates analogues with increased cytotoxicity and reduced insulin-releasing potency. In contrast, the analogues [R8r]Ps-1Pb and [K8k,K19k]Ps-2Pa, incorporating d-amino acid residues to destabilize the α-helical domains, retain potent insulin-releasing activity but are nontoxic to BRIN-BD11 cells at concentrations of 3 μM. [R8r]Ps-1Pb produces a significant increase in insulin release rate at 0.3 nM and [K8k,K19k]Ps-2Pa at 0.01 nM. Both analogues show low hemolytic activity (IC50 > 100 μM) but retain broad-spectrum antimicrobial activity and remain cytotoxic to a range of human tumor cell lines, albeit with lower potency than the naturally occurring peptides. These analogues show potential for development into agents for type 2 diabetes therapy.
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Affiliation(s)
| | | | - Dinesh Srinivasan
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster , Coleraine, BT52 1SA, U.K
| | - Samir Attoub
- Department of Pharmacology, College of Medicine and Health Sciences, United Arab Emirates University , 17666 Al Ain, United Arab Emirates
| | - Maria Luisa Mangoni
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Biochemical Sciences, Sapienza University of Rome , 5 00185 Rome, Italy
| | | | | | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster , Coleraine, BT52 1SA, U.K
| | - J Michael Conlon
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster , Coleraine, BT52 1SA, U.K
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Ojo OO, Srinivasan DK, Owolabi BO, Vasu S, Conlon JM, Flatt PR, Abdel-Wahab YHA. Esculentin-2CHa-Related Peptides Modulate Islet Cell Function and Improve Glucose Tolerance in Mice with Diet-Induced Obesity and Insulin Resistance. PLoS One 2015; 10:e0141549. [PMID: 26512980 PMCID: PMC4626215 DOI: 10.1371/journal.pone.0141549] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/10/2015] [Indexed: 01/08/2023] Open
Abstract
The frog skin host-defense peptide esculentin-2CHa (GFSSIFRGVA10KFASKGLGK D20LAKLGVDLVA30CKISKQC) displays antimicrobial, antitumor, and immunomodulatory properties. This study investigated the antidiabetic actions of the peptide and selected analogues. Esculentin-2CHa stimulated insulin secretion from rat BRIN-BD11 clonal pancreatic β-cells at concentrations greater than 0.3 nM without cytotoxicity by a mechanism involving membrane depolarization and increase of intracellular Ca2+. Insulinotropic activity was attenuated by activation of KATP channels, inhibition of voltage-dependent Ca2+ channels and chelation of extracellular Ca2+. The [L21K], [L24K], [D20K, D27K] and [C31S,C37S] analogues were more potent but less effective than esculentin-2CHa whereas the [L28K] and [C31K] analogues were both more potent and produced a significantly (P < 0.001) greater maximum response. Acute administration of [L28K]esculentin-2CHa (75 nmol/kg body weight) to high fat fed mice with obesity and insulin resistance enhanced glucose tolerance and insulin secretion. Twice-daily administration of this dose of [L28K]esculentin-2CHa for 28 days had no significant effect on body weight, food intake, indirect calorimetry or body composition. However, mice exhibited decreased non-fasting plasma glucose (P < 0.05), increased non-fasting plasma insulin (P < 0.05) as well as improved glucose tolerance and insulin secretion (P < 0.01) following both oral and intraperitoneal glucose loads. Impaired responses of isolated islets from high fat fed mice to established insulin secretagogues were restored by [L28K]esculentin-2CHa treatment. Peptide treatment was accompanied by significantly lower plasma and pancreatic glucagon levels and normalization of α-cell mass. Circulating triglyceride concentrations were decreased but plasma cholesterol and LDL concentrations were not significantly affected. The data encourage further investigation of the potential of esculentin-2CHa related peptides for treatment of patients with type 2 diabetes.
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Affiliation(s)
- Opeolu O. Ojo
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
- School of Sport, Health and Bioscience, University of East London, Stratford, E15 4LZ, United Kingdom
| | - Dinesh K. Srinivasan
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
| | - Bosede O. Owolabi
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
| | - Srividya Vasu
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
| | - J. Michael Conlon
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
| | - Peter R. Flatt
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
| | - Yasser H. A. Abdel-Wahab
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, United Kingdom
- * E-mail:
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