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Fagihi MA, Premathilaka C, O’Neill T, Garré M, Bhattacharjee S. An Investigation into the Acidity-Induced Insulin Agglomeration: Implications for Drug Delivery and Translation. ACS OMEGA 2023; 8:25279-25287. [PMID: 37483254 PMCID: PMC10357556 DOI: 10.1021/acsomega.3c02482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/23/2023] [Indexed: 07/25/2023]
Abstract
Insulin undergoes agglomeration with (subtle) changes in its biochemical environment, including acidity, application of heat, ionic imbalance, and exposure to hydrophobic surfaces. The therapeutic impact of such unwarranted insulin agglomeration is unclear and needs further evaluation. A systematic investigation was conducted on recombinant human insulin-with or without labeling with fluorescein isothiocyanate-while preparing insulin suspensions (0.125, 0.25, and 0.5 mg/mL) at pH 3. The suspensions were incubated (37 °C) and analyzed at different time points (t = 2, 4, 24, 48, and 72 h). Transmission electron microscopy and nanoparticle tracking analysis identified colloidally stable (zeta potential 15 ± 5 mV) spherical agglomerates of unlabeled insulin (100-500 nm). Circular dichroism established the preservation of insulin's secondary structure rich in α-helices despite exposure to an acidic environment (pH 3) for 72 h. Furthermore, fluorescence lifetime imaging microscopy illustrated an acidic core inside these spherical agglomerates, while the acidity gradually lessened toward the periphery. Some of these smaller agglomerates fused to form larger chunks with discrete zones of acidity. The data indicated a primary nucleation-driven mechanism of acid-induced insulin agglomeration under physiologically relevant conditions.
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Affiliation(s)
- Megren
H. A. Fagihi
- School
of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Clinical
Laboratory Sciences Department, College of Applied Medical Sciences, Najran University, Najran 55461, Kingdom of Saudi Arabia
| | - Chanaka Premathilaka
- Institute
of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia
| | - Tiina O’Neill
- Conway
Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Massimiliano Garré
- Super-Resolution
Imaging Consortium, Royal College of Surgeons
in Ireland University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
| | - Sourav Bhattacharjee
- School of
Veterinary Medicine, University College
Dublin, Belfield, Dublin 4, Ireland
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2
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Jiráček J, Žáková L, Marek A. Radiolabeled hormones in insulin research, a minireview. J Labelled Comp Radiopharm 2020; 63:576-581. [PMID: 32909277 DOI: 10.1002/jlcr.3881] [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: 06/15/2020] [Revised: 07/23/2020] [Accepted: 08/30/2020] [Indexed: 11/05/2022]
Abstract
Preparation of both 125 I-labeled insulin and insulin-like growth factor 1 (IGF-1) was critical because it enabled a detailed characterization of binding properties of these important hormones towards their cognate transmembrane receptors. Binding modes of hundreds of hormone derivatives were analyzed using competition radioligand binding assays. This effort has resulted in development of six insulin analogs that are today clinically used for the treatment of diabetes. Here, we will briefly summarize a history of insulin research employing iodinated hormones.
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Affiliation(s)
- Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
| | - Aleš Marek
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
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3
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Dzianová P, Asai S, Chrudinová M, Kosinová L, Potalitsyn P, Šácha P, Hadravová R, Selicharová I, Kříž J, Turkenburg JP, Brzozowski AM, Jiráček J, Žáková L. The efficiency of insulin production and its content in insulin-expressing model β-cells correlate with their Zn 2+ levels. Open Biol 2020; 10:200137. [PMID: 33081637 PMCID: PMC7653362 DOI: 10.1098/rsob.200137] [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: 05/21/2020] [Accepted: 09/24/2020] [Indexed: 12/29/2022] Open
Abstract
Insulin is produced and stored inside the pancreatic β-cell secretory granules, where it is assumed to form Zn2+-stabilized oligomers. However, the actual storage forms of this hormone and the impact of zinc ions on insulin production in vivo are not known. Our initial X-ray fluorescence experiment on granules from native Langerhans islets and insulinoma-derived INS-1E cells revealed a considerable difference in the zinc content. This led our further investigation to evaluate the impact of the intra-granular Zn2+ levels on the production and storage of insulin in different model β-cells. Here, we systematically compared zinc and insulin contents in the permanent INS-1E and BRIN-BD11 β-cells and in the native rat pancreatic islets by flow cytometry, confocal microscopy, immunoblotting, specific messenger RNA (mRNA) and total insulin analysis. These studies revealed an impaired insulin production in the permanent β-cell lines with the diminished intracellular zinc content. The drop in insulin and Zn2+ levels was paralleled by a lower expression of ZnT8 zinc transporter mRNA and hampered proinsulin processing/folding in both permanent cell lines. To summarize, we showed that the disruption of zinc homeostasis in the model β-cells correlated with their impaired insulin and ZnT8 production. This indicates a need for in-depth fundamental research about the role of zinc in insulin production and storage.
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Affiliation(s)
- Petra Dzianová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Seiya Asai
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University, 12840 Prague 2, Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Lucie Kosinová
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague, Czech Republic
| | - Pavlo Potalitsyn
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University, 12840 Prague 2, Czech Republic
| | - Pavel Šácha
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Romana Hadravová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Jan Kříž
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, Videnska 1958/9, 140 21 Prague, Czech Republic
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrzej Marek Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 116 10 Prague 6, Czech Republic
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4
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Sharma D, Singh J. Long-term glycemic control and prevention of diabetes complications in vivo using oleic acid-grafted-chitosan‑zinc-insulin complexes incorporated in thermosensitive copolymer. J Control Release 2020; 323:161-178. [PMID: 32283211 PMCID: PMC7299807 DOI: 10.1016/j.jconrel.2020.04.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/12/2020] [Accepted: 04/07/2020] [Indexed: 12/31/2022]
Abstract
Daily injections for basal insulin therapy are far from ideal resulting in hypo/hyperglycemic episodes associated with fatal complications in type-1 diabetes patients. Here we report a delivery system that provides controlled release of insulin closely mimicking physiological basal insulin requirement for an extended period following a single subcutaneous injection. Stability of insulin was significantly improved by formation of zinc-insulin hexamers, further stabilized by electrostatic complex formation with chitosan polymer. Insulin complexes were homogenously incorporated into PLA-PEG-PLA, a biodegradable thermogel copolymer, that instantaneously forms a subcutaneous gel-depot following injection. Chitosan polymer was hydrophobically modified using oleic acid prior to complex formation with insulin to enable distribution of oleic acid-grafted-chitosan‑zinc-insulin complexes into the hydrophobic core of PLA-PEG-PLA thermogel-copolymer micelles. In vivo, daily administration of marketed long-acting insulin, glargine, resulted in fluctuating blood glucose levels between 91 and 443 mg/dL in type 1 diabetic rats. However, single administration of thermogel copolymeric formulation successfully demonstrated slow diffusion of insulin complexes maintaining peak-free basal insulin level of 21 mU/L for 91 days. Sustained release of basal insulin also correlated with efficient glycemic control (blood glucose <120 mg/dL), prevention of diabetic ketoacidosis and absence of cataract development, unlike other treatment groups. Moreover, there was no sign of inflammation, tissue damage, or collagen deposition around depot site, suggesting exceptional biocompatibility of the formulation for long-term use.
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Affiliation(s)
- Divya Sharma
- Department of Pharmaceutical Sciences, School of Pharmacy, College of Health Professions, North Dakota State University, Fargo 58105, ND, USA.
| | - Jagdish Singh
- Deparment of Pharmaceutical Sciences, North Dakota State University, USA.
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5
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Macháčková K, Mlčochová K, Potalitsyn P, Hanková K, Socha O, Buděšínský M, Muždalo A, Lepšík M, Černeková M, Radosavljević J, Fábry M, Mitrová K, Chrudinová M, Lin J, Yurenko Y, Hobza P, Selicharová I, Žáková L, Jiráček J. Mutations at hypothetical binding site 2 in insulin and insulin-like growth factors 1 and 2 result in receptor- and hormone-specific responses. J Biol Chem 2019; 294:17371-17382. [PMID: 31558604 PMCID: PMC6873181 DOI: 10.1074/jbc.ra119.010072] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 09/23/2019] [Indexed: 11/26/2022] Open
Abstract
Information on how insulin and insulin-like growth factors 1 and 2 (IGF-1 and -2) activate insulin receptors (IR-A and -B) and the IGF-1 receptor (IGF-1R) is crucial for understanding the difference in the biological activities of these peptide hormones. Cryo-EM studies have revealed that insulin uses its binding sites 1 and 2 to interact with IR-A and have identified several critical residues in binding site 2. However, mutagenesis studies suggest that Ile-A10, Ser-A12, Leu-A13, and Glu-A17 also belong to insulin's site 2. Here, to resolve this discrepancy, we mutated these insulin residues and the equivalent residues in IGFs. Our findings revealed that equivalent mutations in the hormones can result in differential biological effects and that these effects can be receptor-specific. We noted that the insulin positions A10 and A17 are important for its binding to IR-A and IR-B and IGF-1R and that A13 is important only for IR-A and IR-B binding. The IGF-1/IGF-2 positions 51/50 and 54/53 did not appear to play critical roles in receptor binding, but mutations at IGF-1 position 58 and IGF-2 position 57 affected the binding. We propose that IGF-1 Glu-58 interacts with IGF-1R Arg-704 and belongs to IGF-1 site 1, a finding supported by the NMR structure of the less active Asp-58–IGF-1 variant. Computational analyses indicated that the aforementioned mutations can affect internal insulin dynamics and inhibit adoption of a receptor-bound conformation, important for binding to receptor site 1. We provide a molecular model and alternative hypotheses for how the mutated insulin residues affect activity.
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Affiliation(s)
- Kateřina Macháčková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Květoslava Mlčochová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Pavlo Potalitsyn
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Kateřina Hanková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Ondřej Socha
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Anja Muždalo
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Martin Lepšík
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Michaela Černeková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Jelena Radosavljević
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Milan Fábry
- Institute of Molecular Genetics, Czech Academy of Sciences, 166 37 Prague 6, Czech Republic
| | - Katarína Mitrová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Jingjing Lin
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Yevgen Yurenko
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 166 10 Prague 6, Czech Republic
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6
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Desmond JL, Koner D, Meuwly M. Probing the Differential Dynamics of the Monomeric and Dimeric Insulin from Amide-I IR Spectroscopy. J Phys Chem B 2019; 123:6588-6598. [PMID: 31318551 DOI: 10.1021/acs.jpcb.9b04628] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The monomer-dimer equilibrium for insulin is one of the essential steps in forming the receptor-binding competent monomeric form of the hormone. Despite this importance, the thermodynamic stability, in particular for modified insulins, is quite poorly understood, in part, due to experimental difficulties. This work explores one- and two-dimensional infrared spectroscopy in the range of the amide-I band for the hydrated monomeric and dimeric wild-type hormone. It is found that for the monomer the frequency fluctuation correlation function (FFCF) and the one-dimensional infrared spectra are position sensitive. The spectra of the -CO probes at the dimerization interface (residues Phe24, Phe25, and Tyr26) split and indicate an asymmetry despite the overall (formal) point symmetry of the dimer structure. Also, the decay times of the FFCF for the same -CO probe in the monomer and the dimer can differ by up to 1 order of magnitude, for example, for residue PheB24, which is solvent exposed for the monomer but at the interface for the dimer. The spectroscopic shifts correlate approximately with the average number of hydration waters and the magnitude of the FFCF at time zero. However, this correlation is only qualitative due to the heterogeneous and highly dynamical environment. Based on density functional theory calculations, the dominant contribution for solvent-exposed -CO is found to arise from the surrounding water (∼75%), whereas the protein environment contributes considerably less. The results suggest that infrared spectroscopy is a positionally sensitive probe of insulin dimerization, in particular in conjunction with isotopic labeling of the probe.
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Affiliation(s)
- Jasmine L Desmond
- Department of Chemistry , University of Basel , Klingelbergstrasse 80 , 4056 Basel , Switzerland
| | - Debasish Koner
- Department of Chemistry , University of Basel , Klingelbergstrasse 80 , 4056 Basel , Switzerland
| | - Markus Meuwly
- Department of Chemistry , University of Basel , Klingelbergstrasse 80 , 4056 Basel , Switzerland
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7
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Iliev S, Gocheva G, Ivanova N, Atanasova B, Petrova J, Madjarova G, Ivanova A. Identification and computational characterization of isomers with cis and trans amide bonds in folate and its analogues. Phys Chem Chem Phys 2018; 20:28818-28831. [PMID: 30418443 DOI: 10.1039/c8cp04304c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Folate and its synthetic analogues, called antifolates, are known to have diverse bio-applications, for example as cell proliferation stimulators or anticancer drugs. Their molecular structure is important for performing the required biological activity. Since all folate-derived ligands contain a peptide-like amide bond, its configuration is one of the key components for the functional fitness of such compounds. During the modelling of folate and three of its derivatives - methotrexate, 5-methyl tetrahydrofolate, and pteroyl ornithine, we registered significant population of the cis isomers along the amide bond. The properties of the cis and trans forms of the ligands in saline are studied in detail by classical atomistic molecular dynamics and by quantum chemical methods. The calculations predict high probability for coexistence of the cis isomers for two of the ligands. The energetic instability of the cis form is explained with a σ-character admixture into the C[double bond, length as m-dash]O(π) bond, while its magnitude is attributed to the pattern of local electron density redistribution. The cis forms of all molecules have markedly slower structural dynamics than the trans ones, which might affect their behavior in vivo.
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Affiliation(s)
- Stoyan Iliev
- Laboratory of Quantum and Computational Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria.
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8
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Chrudinová M, Žáková L, Marek A, Socha O, Buděšínský M, Hubálek M, Pícha J, Macháčková K, Jiráček J, Selicharová I. A versatile insulin analog with high potency for both insulin and insulin-like growth factor 1 receptors: Structural implications for receptor binding. J Biol Chem 2018; 293:16818-16829. [PMID: 30213860 PMCID: PMC6204900 DOI: 10.1074/jbc.ra118.004852] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/05/2018] [Indexed: 12/02/2022] Open
Abstract
Insulin and insulin-like growth factor 1 (IGF-1) are closely related hormones involved in the regulation of metabolism and growth. They elicit their functions through activation of tyrosine kinase–type receptors: insulin receptors (IR-A and IR-B) and IGF-1 receptor (IGF-1R). Despite similarity in primary and three-dimensional structures, insulin and IGF-1 bind the noncognate receptor with substantially reduced affinity. We prepared [d-HisB24, GlyB31, TyrB32]-insulin, which binds all three receptors with high affinity (251 or 338% binding affinity to IR-A respectively to IR-B relative to insulin and 12.4% binding affinity to IGF-1R relative to IGF-1). We prepared other modified insulins with the aim of explaining the versatility of [d-HisB24, GlyB31, TyrB32]-insulin. Through structural, activity, and kinetic studies of these insulin analogs, we concluded that the ability of [d-HisB24, GlyB31, TyrB32]-insulin to stimulate all three receptors is provided by structural changes caused by a reversed chirality at the B24 combined with the extension of the C terminus of the B chain by two extra residues. We assume that the structural changes allow the directing of the B chain C terminus to some extra interactions with the receptors. These unusual interactions lead to a decrease of dissociation rate from the IR and conversely enable easier association with IGF-1R. All of the structural changes were made at the hormones' Site 1, which is thought to interact with the Site 1 of the receptors. The results of the study suggest that merely modifications of Site 1 of the hormone are sufficient to change the receptor specificity of insulin.
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Affiliation(s)
- Martina Chrudinová
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Aleš Marek
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Ondřej Socha
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Miloš Buděšínský
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Martin Hubálek
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Jan Pícha
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Kateřina Macháčková
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Jiří Jiráček
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Irena Selicharová
- From the Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
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9
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Fabre B, Pícha J, Selicharová I, Žáková L, Chrudinová M, Hajduch J, Jiráček J. Probing Tripodal Peptide Scaffolds as Insulin and IGF-1 Receptor Ligands. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Benjamin Fabre
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Jan Pícha
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Jan Hajduch
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry; Czech Academy of Sciences, v.v.i.; Flemingovo n. 2, 16610 6 Praha Czech Republic
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10
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Březina K, Duboué-Dijon E, Palivec V, Jiráček J, Křížek T, Viola CM, Ganderton TR, Brzozowski AM, Jungwirth P. Can Arginine Inhibit Insulin Aggregation? A Combined Protein Crystallography, Capillary Electrophoresis, and Molecular Simulation Study. J Phys Chem B 2018; 122:10069-10076. [DOI: 10.1021/acs.jpcb.8b06557] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Kryštof Březina
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 542/2, 160 00 Prague, Czech Republic
| | - Elise Duboué-Dijon
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 542/2, 160 00 Prague, Czech Republic
| | - Vladimír Palivec
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 542/2, 160 00 Prague, Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 542/2, 160 00 Prague, Czech Republic
| | - Tomáš Křížek
- Faculty of Science, Department of Analytical Chemistry, Charles University, Albertov 2030, 12840 Prague 2, Czech Republic
| | - Cristina M. Viola
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, United Kingdom
| | - Timothy R. Ganderton
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrzej M. Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, United Kingdom
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 542/2, 160 00 Prague, Czech Republic
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11
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Raghunathan S, El Hage K, Desmond JL, Zhang L, Meuwly M. The Role of Water in the Stability of Wild-type and Mutant Insulin Dimers. J Phys Chem B 2018; 122:7038-7048. [DOI: 10.1021/acs.jpcb.8b04448] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shampa Raghunathan
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Krystel El Hage
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Jasmine L. Desmond
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Lixian Zhang
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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12
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Zielińska J, Stadnik J, Bierczyńska-Krzysik A, Stadnik D. Identification of N-Terminally Truncated Derivatives of Insulin Analogs Formed in Pharmaceutical Formulations. Pharm Res 2018; 35:143. [PMID: 29770892 PMCID: PMC5956049 DOI: 10.1007/s11095-018-2426-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 05/06/2018] [Indexed: 11/18/2022]
Abstract
PURPOSE Isolation and identification of unknown impurities of recombinant insulin lispro (produced at IBA) formed during accelerated stability testing of pharmaceutical solutions. For comparative purposes also commercially available formulations of recombinant human insulin (Humulin S®; Lilly), recombinant insulin lispro (Humalog®; Lilly), recombinant insulin aspart (NovoRapid® Penfill®; Novo Nordisk), recombinant insulin detemir (Levemir®; Novo Nordisk) and recombinant insulin glargine (Lantus®; Sanofi-Aventis) were analyzed. METHODS The impurities of insulin analogs were isolated by RP-HPLC and identified with peptide mass fingerprinting using MALDI-TOF/TOF mass spectrometry. RESULTS The identified derivatives were N-terminally truncated insulin analog impurities of decreased molecular mass of 119, 147 and 377 Da related to the original protein. The modifications resulting in a mass decrease were detected at the N-terminus of B chains of insulin lispro, insulin aspart, human insulin, insulin glargine, insulin detemir in all tested formulations. To our knowledge it is the first time that these impurities are reported. CONCLUSIONS The following derivatives formed by truncation of the B chain in insulin analogs were identified in pharmaceutical formulations: desPheB1-N-formyl-ValB2 derivative, desPheB1 derivative, pyroGluB4 derivative.
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Affiliation(s)
- Joanna Zielińska
- Institute of Biotechnology and Antibiotics (IBA), Starościńska 5, 02-516, Warsaw, Poland
| | - Jacek Stadnik
- Institute of Biotechnology and Antibiotics (IBA), Starościńska 5, 02-516, Warsaw, Poland
| | | | - Dorota Stadnik
- Institute of Biotechnology and Antibiotics (IBA), Starościńska 5, 02-516, Warsaw, Poland.
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13
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Selivanova OM, Grishin SY, Glyakina AV, Sadgyan AS, Ushakova NI, Galzitskaya OV. Analysis of Insulin Analogs and the Strategy of Their Further Development. BIOCHEMISTRY (MOSCOW) 2018; 83:S146-S162. [DOI: 10.1134/s0006297918140122] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/09/2017] [Indexed: 08/30/2023]
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14
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van Lierop B, Ong SC, Belgi A, Delaine C, Andrikopoulos S, Haworth NL, Menting JG, Lawrence MC, Robinson AJ, Forbes BE. Insulin in motion: The A6-A11 disulfide bond allosterically modulates structural transitions required for insulin activity. Sci Rep 2017; 7:17239. [PMID: 29222417 PMCID: PMC5722942 DOI: 10.1038/s41598-017-16876-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/17/2017] [Indexed: 01/10/2023] Open
Abstract
The structural transitions required for insulin to activate its receptor and initiate regulation of glucose homeostasis are only partly understood. Here, using ring-closing metathesis, we substitute the A6-A11 disulfide bond of insulin with a rigid, non-reducible dicarba linkage, yielding two distinct stereo-isomers (cis and trans). Remarkably, only the cis isomer displays full insulin potency, rapidly lowering blood glucose in mice (even under insulin-resistant conditions). It also posseses reduced mitogenic activity in vitro. Further biophysical, crystallographic and molecular-dynamics analyses reveal that the A6-A11 bond configuration directly affects the conformational flexibility of insulin A-chain N-terminal helix, dictating insulin’s ability to engage its receptor. We reveal that in native insulin, contraction of the Cα-Cα distance of the flexible A6-A11 cystine allows the A-chain N-terminal helix to unwind to a conformation that allows receptor engagement. This motion is also permitted in the cis isomer, with its shorter Cα-Cα distance, but prevented in the extended trans analogue. These findings thus illuminate for the first time the allosteric role of the A6-A11 bond in mediating the transition of the hormone to an active conformation, significantly advancing our understanding of insulin action and opening up new avenues for the design of improved therapeutic analogues.
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Affiliation(s)
- Bianca van Lierop
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Shee Chee Ong
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Carlie Delaine
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | | | - Naomi L Haworth
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.,Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia.,School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria, 3216, Australia
| | - John G Menting
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia
| | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Parkville, Victoria, 3050, Australia
| | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.
| | - Briony E Forbes
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia.
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15
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Computational study of the activity, dynamics, energetics and conformations of insulin analogues using molecular dynamics simulations: Application to hyperinsulinemia and the critical residue B26. Biochem Biophys Rep 2017; 11:182-190. [PMID: 28955783 PMCID: PMC5614686 DOI: 10.1016/j.bbrep.2017.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 04/13/2017] [Indexed: 12/15/2022] Open
Abstract
Due to the increasing prevalence of diabetes, finding therapeutic analogues for insulin has become an urgent issue. While many experimental studies have been performed towards this end, they have limited scope to examine all aspects of the effect of a mutation. Computational studies can help to overcome these limitations, however, relatively few studies that focus on insulin analogues have been performed to date. Here, we present a comprehensive computational study of insulin analogues-three mutant insulins that have been identified with hyperinsulinemia and three mutations on the critical B26 residue that exhibit similar binding affinity to the insulin receptor-using molecular dynamics simulations with the aim of predicting how mutations of insulin affect its activity, dynamics, energetics and conformations. The time evolution of the conformers is studied in long simulations. The probability density function and potential of mean force calculations are performed on each insulin analogue to unravel the effect of mutations on the dynamics and energetics of insulin activation. Our conformational study can decrypt the key features and molecular mechanisms that are responsible for an enhanced or reduced activity of an insulin analogue. We find two key results: 1) hyperinsulinemia may be due to the drastically reduced activity (and binding affinity) of the mutant insulins. 2) Y26BS and Y26BE are promising therapeutic candidates for insulin as they are more active than WT-insulin. The analysis in this work can be readily applied to any set of mutations on insulin to guide development of more effective therapeutic analogues.
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16
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Mohammadiarani H, Vashisth H. Insulin mimetic peptide S371 folds into a helical structure. J Comput Chem 2017; 38:1158-1166. [DOI: 10.1002/jcc.24746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 12/14/2016] [Accepted: 01/07/2017] [Indexed: 01/26/2023]
Affiliation(s)
| | - Harish Vashisth
- Department of Chemical Engineering; University of New Hampshire; Durham New Hampshire
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17
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Fabre B, Pícha J, Vaněk V, Selicharová I, Chrudinová M, Collinsová M, Žáková L, Buděšínský M, Jiráček J. Synthesis and Evaluation of a Library of Trifunctional Scaffold-Derived Compounds as Modulators of the Insulin Receptor. ACS COMBINATORIAL SCIENCE 2016; 18:710-722. [PMID: 27936668 DOI: 10.1021/acscombsci.6b00132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We designed a combinatorial library of trifunctional scaffold-derived compounds, which were derivatized with 30 different in-house-made azides. The compounds were proposed to mimic insulin receptor (IR)-binding epitopes in the insulin molecule and bind to and activate this receptor. This work has enabled us to test our synthetic and biological methodology and to prove its robustness and reliability for the solid-phase synthesis and testing of combinatorial libraries of the trifunctional scaffold-derived compounds. Our effort resulted in the discovery of two compounds, which were able to weakly induce the autophosphorylation of IR and weakly bind to this receptor at a 0.1 mM concentration. Despite these modest biological results, which well document the well-known difficulty in modulating protein-protein interactions, this study represents a unique example of targeting the IR with a set of nonpeptide compounds that were specifically designed and synthesized for this purpose. We believe that this work can open new perspectives for the development of next-generation insulin mimetics based on the scaffold structure.
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Affiliation(s)
- Benjamin Fabre
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Jan Pícha
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Václav Vaněk
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Michaela Collinsová
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Miloš Buděšínský
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry
and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 16610 Praha 6, Czech Republic
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18
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Papaioannou A, Kuyucak S, Kuncic Z. Elucidating the Activation Mechanism of the Insulin-Family Proteins with Molecular Dynamics Simulations. PLoS One 2016; 11:e0161459. [PMID: 27548502 PMCID: PMC4993506 DOI: 10.1371/journal.pone.0161459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 08/05/2016] [Indexed: 12/27/2022] Open
Abstract
The insulin-family proteins bind to their own receptors, but insulin-like growth factor II (IGF-II) can also bind to the A isoform of the insulin receptor (IR-A), activating unique and alternative signaling pathways from those of insulin. Although extensive studies of insulin have revealed that its activation is associated with the opening of the B chain-C terminal (BC-CT), the activation mechanism of the insulin-like growth factors (IGFs) still remains unknown. Here, we present the first comprehensive study of the insulin-family proteins comparing their activation process and mechanism using molecular dynamics simulations to reveal new insights into their specificity to the insulin receptor. We have found that all the proteins appear to exhibit similar stochastic dynamics in their conformational change to an active state. For the IGFs, our simulations show that activation involves two opening locations: the opening of the BC-CT section away from the core, similar to insulin; and the additional opening of the BC-CT section away from the C domain. Furthermore, we have found that these two openings occur simultaneously in IGF-I, but not in IGF-II, where they can occur independently. This suggests that the BC-CT section and the C domain behave as a unified domain in IGF-I, but as two independent domains in IGF-II during the activation process, implying that the IGFs undergo different activation mechanisms for receptor binding. The probabilities of the active and inactive states of the proteins suggest that IGF-II is hyperactive compared to IGF-I. The hinge residue and the hydrophobic interactions in the core are found to play a critical role in the stability and activity of IGFs. Overall, our simulations have elucidated the crucial differences and similarities in the activation mechanisms of the insulin-family proteins, providing new insights into the molecular mechanisms responsible for the observed differences between IGF-I and IGF-II in receptor binding.
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Affiliation(s)
- Anastasios Papaioannou
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
- School of Physics, University of Sydney, Sydney, NSW, Australia
- * E-mail: (AP); (ZK)
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, NSW, Australia
| | - Zdenka Kuncic
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
- School of Physics, University of Sydney, Sydney, NSW, Australia
- * E-mail: (AP); (ZK)
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19
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Hexnerová R, Křížková K, Fábry M, Sieglová I, Kedrová K, Collinsová M, Ullrichová P, Srb P, Williams C, Crump MP, Tošner Z, Jiráček J, Veverka V, Žáková L. Probing Receptor Specificity by Sampling the Conformational Space of the Insulin-like Growth Factor II C-domain. J Biol Chem 2016; 291:21234-21245. [PMID: 27510031 PMCID: PMC5076530 DOI: 10.1074/jbc.m116.741041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Indexed: 01/22/2023] Open
Abstract
Insulin and insulin-like growth factors I and II are closely related protein hormones. Their distinct evolution has resulted in different yet overlapping biological functions with insulin becoming a key regulator of metabolism, whereas insulin-like growth factors (IGF)-I/II are major growth factors. Insulin and IGFs cross-bind with different affinities to closely related insulin receptor isoforms A and B (IR-A and IR-B) and insulin-like growth factor type I receptor (IGF-1R). Identification of structural determinants in IGFs and insulin that trigger their specific signaling pathways is of increasing importance in designing receptor-specific analogs with potential therapeutic applications. Here, we developed a straightforward protocol for production of recombinant IGF-II and prepared six IGF-II analogs with IGF-I-like mutations. All modified molecules exhibit significantly reduced affinity toward IR-A, particularly the analogs with a Pro-Gln insertion in the C-domain. Moreover, one of the analogs has enhanced binding affinity for IGF-1R due to a synergistic effect of the Pro-Gln insertion and S29N point mutation. Consequently, this analog has almost a 10-fold higher IGF-1R/IR-A binding specificity in comparison with native IGF-II. The established IGF-II purification protocol allowed for cost-effective isotope labeling required for a detailed NMR structural characterization of IGF-II analogs that revealed a link between the altered binding behavior of selected analogs and conformational rearrangement of their C-domains.
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Affiliation(s)
- Rozálie Hexnerová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic, Faculty of Science, Charles University in Prague, Albertov 6, Prague 128 43, Czech Republic
| | - Květoslava Křížková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic, Faculty of Science, Charles University in Prague, Albertov 6, Prague 128 43, Czech Republic
| | - Milan Fábry
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, v.v.i., Vídeňská 1083, 142 20 Prague 4, Czech Republic, and
| | - Irena Sieglová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Kateřina Kedrová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic, Faculty of Science, Charles University in Prague, Albertov 6, Prague 128 43, Czech Republic
| | - Michaela Collinsová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Pavlína Ullrichová
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Pavel Srb
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Christopher Williams
- Department of Organic and Biological Chemistry, School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Matthew P Crump
- Department of Organic and Biological Chemistry, School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Zdeněk Tošner
- Faculty of Science, Charles University in Prague, Albertov 6, Prague 128 43, Czech Republic
| | - Jiří Jiráček
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Václav Veverka
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic,
| | - Lenka Žáková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic,
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20
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Pandyarajan V, Phillips NB, Rege N, Lawrence MC, Whittaker J, Weiss MA. Contribution of TyrB26 to the Function and Stability of Insulin: STRUCTURE-ACTIVITY RELATIONSHIPS AT A CONSERVED HORMONE-RECEPTOR INTERFACE. J Biol Chem 2016; 291:12978-90. [PMID: 27129279 DOI: 10.1074/jbc.m115.708347] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 11/06/2022] Open
Abstract
Crystallographic studies of insulin bound to receptor domains have defined the primary hormone-receptor interface. We investigated the role of Tyr(B26), a conserved aromatic residue at this interface. To probe the evolutionary basis for such conservation, we constructed 18 variants at B26. Surprisingly, non-aromatic polar or charged side chains (such as Glu, Ser, or ornithine (Orn)) conferred high activity, whereas the weakest-binding analogs contained Val, Ile, and Leu substitutions. Modeling of variant complexes suggested that the B26 side chains pack within a shallow depression at the solvent-exposed periphery of the interface. This interface would disfavor large aliphatic side chains. The analogs with highest activity exhibited reduced thermodynamic stability and heightened susceptibility to fibrillation. Perturbed self-assembly was also demonstrated in studies of the charged variants (Orn and Glu); indeed, the Glu(B26) analog exhibited aberrant aggregation in either the presence or absence of zinc ions. Thus, although Tyr(B26) is part of insulin's receptor-binding surface, our results suggest that its conservation has been enjoined by the aromatic ring's contributions to native stability and self-assembly. We envisage that such classical structural relationships reflect the implicit threat of toxic misfolding (rather than hormonal function at the receptor level) as a general evolutionary determinant of extant protein sequences.
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Affiliation(s)
| | | | | | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia, Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - Michael A Weiss
- From the Departments of Biochemistry, Medicine, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106,
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21
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Viková J, Collinsová M, Kletvíková E, Buděšínský M, Kaplan V, Žáková L, Veverka V, Hexnerová R, Aviñó RJT, Straková J, Selicharová I, Vaněk V, Wright DW, Watson CJ, Turkenburg JP, Brzozowski AM, Jiráček J. Rational steering of insulin binding specificity by intra-chain chemical crosslinking. Sci Rep 2016; 6:19431. [PMID: 26792393 PMCID: PMC4726324 DOI: 10.1038/srep19431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/11/2015] [Indexed: 12/14/2022] Open
Abstract
Insulin is a key hormone of human metabolism with major therapeutic importance for both types of diabetes. New insulin analogues with more physiological profiles and better glycemic control are needed, especially analogues that preferentially bind to the metabolic B-isoform of insulin receptor (IR-B). Here, we aimed to stabilize and modulate the receptor-compatible conformation of insulin by covalent intra-chain crosslinking within its B22-B30 segment, using the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction of azides and alkynes. This approach resulted in 14 new, systematically crosslinked insulin analogues whose structures and functions were extensively characterized and correlated. One of the analogues, containing a B26-B29 triazole bridge, was highly active in binding to both IR isoforms, with a significant preference for IR-B. Our results demonstrate the potential of chemistry-driven modulation of insulin function, also shedding new light on the functional importance of hormone's B-chain C-terminus for its IR-B specificity.
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Affiliation(s)
- Jitka Viková
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Michaela Collinsová
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Emília Kletvíková
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Vojtěch Kaplan
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Václav Veverka
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Rozálie Hexnerová
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Roberto J. Tarazona Aviñó
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Jana Straková
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Václav Vaněk
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
| | - Daniel W. Wright
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Christopher J. Watson
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Andrzej M. Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, the Czech Academy of Sciences, v.v.i., Flemingovo n. 2, 166 10 Praha 6, Czech Republic
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22
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Papaioannou A, Kuyucak S, Kuncic Z. Molecular Dynamics Simulations of Insulin: Elucidating the Conformational Changes that Enable Its Binding. PLoS One 2015; 10:e0144058. [PMID: 26629689 PMCID: PMC4668001 DOI: 10.1371/journal.pone.0144058] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/12/2015] [Indexed: 01/30/2023] Open
Abstract
A sequence of complex conformational changes is required for insulin to bind to the insulin receptor. Recent experimental evidence points to the B chain C-terminal (BC-CT) as the location of these changes in insulin. Here, we present molecular dynamics simulations of insulin that reveal new insights into the structural changes occurring in the BC-CT. We find three key results: 1) The opening of the BC-CT is inherently stochastic and progresses through an open and then a “wide-open” conformation—the wide-open conformation is essential for receptor binding, but occurs only rarely. 2) The BC-CT opens with a zipper-like mechanism, with a hinge at the Phe24 residue, and is maintained in the dominant closed/inactive state by hydrophobic interactions of the neighboring Tyr26, the critical residue where opening of the BC-CT (activation of insulin) is initiated. 3) The mutation Y26N is a potential candidate as a therapeutic insulin analogue. Overall, our results suggest that the binding of insulin to its receptor is a highly dynamic and stochastic process, where initial docking occurs in an open conformation and full binding is facilitated through interactions of insulin receptor residues with insulin in its wide-open conformation.
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Affiliation(s)
- Anastasios Papaioannou
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
- School of Physics, University of Sydney, Sydney, NSW, Australia
- * E-mail:
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, NSW, Australia
| | - Zdenka Kuncic
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
- School of Physics, University of Sydney, Sydney, NSW, Australia
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23
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Rawat S, Gupta P, Kumar A, Garg P, Suri CR, Sahoo DK. Molecular Mechanism of Poly(vinyl alcohol) Mediated Prevention of Aggregation and Stabilization of Insulin in Nanoparticles. Mol Pharm 2015; 12:1018-30. [DOI: 10.1021/mp5003653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Sanjay Rawat
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Pawan Gupta
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, Mohali 160062, India
| | - Anil Kumar
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Prabha Garg
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, Mohali 160062, India
| | - C. Raman Suri
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Debendra K. Sahoo
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
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24
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Affiliation(s)
- Pierre De Meyts
- Department of Diabetes Biology; Novo Nordisk A/S; Måløv Denmark
- De Meyts R&D Consulting; Kraainem; Belgium
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25
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Bathula SR, Akondi SM, Mainkar PS, Chandrasekhar S. “Pruning of biomolecules and natural products (PBNP)”: an innovative paradigm in drug discovery. Org Biomol Chem 2015; 13:6432-48. [DOI: 10.1039/c5ob00403a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Smart Schneider: ‘Nature’ is the most intelligent tailor with an ability to utilize the resources. Researchers are still at an infant stage learning this art. The present review highlights some of the man made pruning of bio-molecules and NPs (PBNP) in finding chemicals with a better therapeutic index.
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Affiliation(s)
- Surendar Reddy Bathula
- Division of Natural Products Chemistry CSIR-Indian Institute of Chemical Technology
- Hyderabad
- 500007 India
| | - Srirama Murthy Akondi
- Division of Natural Products Chemistry CSIR-Indian Institute of Chemical Technology
- Hyderabad
- 500007 India
| | - Prathama S. Mainkar
- Division of Natural Products Chemistry CSIR-Indian Institute of Chemical Technology
- Hyderabad
- 500007 India
| | - Srivari Chandrasekhar
- Division of Natural Products Chemistry CSIR-Indian Institute of Chemical Technology
- Hyderabad
- 500007 India
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26
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Křížková K, Veverka V, Maletínská L, Hexnerová R, Brzozowski AM, Jiráček J, Žáková L. Structural and functional study of the GlnB22-insulin mutant responsible for maturity-onset diabetes of the young. PLoS One 2014; 9:e112883. [PMID: 25423173 PMCID: PMC4244080 DOI: 10.1371/journal.pone.0112883] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 10/21/2014] [Indexed: 12/04/2022] Open
Abstract
The insulin gene mutation c.137G>A (R46Q), which changes an arginine at the B22 position of the mature hormone to glutamine, causes the monogenic diabetes variant maturity-onset diabetes of the young (MODY). In MODY patients, this mutation is heterozygous, and both mutant and wild-type (WT) human insulin are produced simultaneously. However, the patients often depend on administration of exogenous insulin. In this study, we chemically synthesized the MODY mutant [GlnB22]-insulin and characterized its biological and structural properties. The chemical synthesis of this insulin analogue revealed that its folding ability is severely impaired. In vitro and in vivo tests showed that its binding affinity and biological activity are reduced (both approximately 20% that of human insulin). Comparison of the solution structure of [GlnB22]-insulin with the solution structure of native human insulin revealed that the most significant structural effect of the mutation is distortion of the B20-B23 β-turn, leading to liberation of the B chain C-terminus from the protein core. The distortion of the B20-B23 β-turn is caused by the extended conformational freedom of the GlnB22 side chain, which is no longer anchored in a hydrogen bonding network like the native ArgB22. The partially disordered [GlnB22]-insulin structure appears to be one reason for the reduced binding potency of this mutant and may also be responsible for its low folding efficiency in vivo. The altered orientation and flexibility of the B20-B23 β-turn may interfere with the formation of disulfide bonds in proinsulin bearing the R46Q (GlnB22) mutation. This may also have a negative effect on the WT proinsulin simultaneously biosynthesized in β-cells and therefore play a major role in the development of MODY in patients producing [GlnB22]-insulin.
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Affiliation(s)
- Květoslava Křížková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Václav Veverka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Lenka Maletínská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Rozálie Hexnerová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Andrzej M. Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York, YO10 5DD, United Kingdom
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- * E-mail:
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27
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Vashisth H. Flexibility in the insulin receptor ectodomain enables docking of insulin in crystallographic conformation observed in a hormone-bound microreceptor. MEMBRANES 2014; 4:730-46. [PMID: 25309993 PMCID: PMC4289863 DOI: 10.3390/membranes4040730] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/18/2014] [Accepted: 10/05/2014] [Indexed: 12/11/2022]
Abstract
Insulin binding to the insulin receptor (IR) is the first key step in initiating downstream signaling cascades for glucose homeostasis in higher organisms. The molecular details of insulin recognition by IR are not yet completely understood, but a picture of hormone/receptor interactions at one of the epitopes (Site 1) is beginning to emerge from recent structural evidence. However, insulin-bound structures of truncated IR suggest that crystallographic conformation of insulin cannot be accommodated in the full IR ectodomain due to steric overlap of insulin with the first two type III fibronectin domains (F1 and F2), which are contributed to the insulin binding-pocket by the second subunit in the IR homodimer. A conformational change in the F1-F2 pair has thus been suggested. In this work, we present an all-atom structural model of complex of insulin and the IR ectodomain, where no structural overlap of insulin with the receptor domains (F1 and F2) is observed. This structural model was arrived at by flexibly fitting parts of our earlier insulin/IR all-atom model into the simulated density maps of crystallized constructs combined with conformational sampling from apo-IR solution conformations. Importantly, our experimentally-consistent model helps rationalize yet unresolved Site.
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Affiliation(s)
- Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, 33 Academic Way, Durham,NH 03824, USA.
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28
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Žáková L, Kletvíková E, Lepšík M, Collinsová M, Watson CJ, Turkenburg JP, Jiráček J, Brzozowski AM. Human insulin analogues modified at the B26 site reveal a hormone conformation that is undetected in the receptor complex. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2765-74. [PMID: 25286859 PMCID: PMC4188015 DOI: 10.1107/s1399004714017775] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/01/2014] [Indexed: 11/10/2022]
Abstract
The structural characterization of the insulin-insulin receptor (IR) interaction still lacks the conformation of the crucial B21-B30 insulin region, which must be different from that in its storage forms to ensure effective receptor binding. Here, it is shown that insulin analogues modified by natural amino acids at the TyrB26 site can represent an active form of this hormone. In particular, [AsnB26]-insulin and [GlyB26]-insulin attain a B26-turn-like conformation that differs from that in all known structures of the native hormone. It also matches the receptor interface, avoiding substantial steric clashes. This indicates that insulin may attain a B26-turn-like conformation upon IR binding. Moreover, there is an unexpected, but significant, binding specificity of the AsnB26 mutant for predominantly the metabolic B isoform of the receptor. As it is correlated with the B26 bend of the B-chain of the hormone, the structures of AsnB26 analogues may provide the first structural insight into the structural origins of differential insulin signalling through insulin receptor A and B isoforms.
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Affiliation(s)
- Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Emília Kletvíková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Martin Lepšík
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Michaela Collinsová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Christopher J. Watson
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, England
| | - Johan P. Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, England
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Andrzej M. Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5DD, England
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29
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Ksenofontova OI. [Introduction of mutations in insulin molecule: positive and negative mutations]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2014; 60:430-7. [PMID: 25249526 DOI: 10.18097/pbmc20146004430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Introduction of mutations in an insulin molecule is one of the important approaches to drug development for treatment of diabetes mellitus. Generally, usage of mutations is aimed at activation of insulin and insulin receptor interaction. Such mutations can be considered as positive. Mutations that reduce the binding efficacy are negative. There are neutral mutations as well. This article considers both natural mutations that are typical for various members of the insulin superfamily and artificial ones which are introduced to improve the insulin pharmacological characteristics. Data presented here can be useful in developing new effective insulin analogues for treatment of diabetes mellitus.
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30
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Abstract
Insulin provides a classical model of a globular protein, yet how the hormone changes conformation to engage its receptor has long been enigmatic. Interest has focused on the C-terminal B-chain segment, critical for protective self-assembly in β cells and receptor binding at target tissues. Insight may be obtained from truncated "microreceptors" that reconstitute the primary hormone-binding site (α-subunit domains L1 and αCT). We demonstrate that, on microreceptor binding, this segment undergoes concerted hinge-like rotation at its B20-B23 β-turn, coupling reorientation of Phe(B24) to a 60° rotation of the B25-B28 β-strand away from the hormone core to lie antiparallel to the receptor's L1-β2 sheet. Opening of this hinge enables conserved nonpolar side chains (Ile(A2), Val(A3), Val(B12), Phe(B24), and Phe(B25)) to engage the receptor. Restraining the hinge by nonstandard mutagenesis preserves native folding but blocks receptor binding, whereas its engineered opening maintains activity at the price of protein instability and nonnative aggregation. Our findings rationalize properties of clinical mutations in the insulin family and provide a previously unidentified foundation for designing therapeutic analogs. We envisage that a switch between free and receptor-bound conformations of insulin evolved as a solution to conflicting structural determinants of biosynthesis and function.
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31
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Kosinová L, Veverka V, Novotná P, Collinsová M, Urbanová M, Moody NR, Turkenburg JP, Jiráček J, Brzozowski AM, Žáková L. Insight into the structural and biological relevance of the T/R transition of the N-terminus of the B-chain in human insulin. Biochemistry 2014; 53:3392-402. [PMID: 24819248 PMCID: PMC4047818 DOI: 10.1021/bi500073z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
![]()
The N-terminus of the B-chain of
insulin may adopt two alternative
conformations designated as the T- and R-states. Despite the recent
structural insight into insulin–insulin receptor (IR) complexes,
the physiological relevance of the T/R transition is still unclear.
Hence, this study focused on the rational design, synthesis, and characterization
of human insulin analogues structurally locked in expected R- or T-states.
Sites B3, B5, and B8, capable of affecting the conformation of the
N-terminus of the B-chain, were subjects of rational substitutions
with amino acids with specific allowed and disallowed dihedral φ
and ψ main-chain angles. α-Aminoisobutyric acid was systematically
incorporated into positions B3, B5, and B8 for stabilization of the
R-state, and N-methylalanine and d-proline
amino acids were introduced at position B8 for stabilization of the
T-state. IR affinities of the analogues were compared and correlated
with their T/R transition ability and analyzed against their crystal
and nuclear magnetic resonance structures. Our data revealed that
(i) the T-like state is indeed important for the folding efficiency
of (pro)insulin, (ii) the R-state is most probably incompatible with
an active form of insulin, (iii) the R-state cannot be induced or
stabilized by a single substitution at a specific site, and (iv) the
B1–B8 segment is capable of folding into a variety of low-affinity
T-like states. Therefore, we conclude that the active conformation
of the N-terminus of the B-chain must be different from the “classical”
T-state and that a substantial flexibility of the B1–B8 segment,
where GlyB8 plays a key role, is a crucial prerequisite for an efficient
insulin–IR interaction.
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Affiliation(s)
- Lucie Kosinová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
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32
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Garrocho-Villegas V, Aguilar C R, Sánchez de Jiménez E. Insights into the TOR-S6K signaling pathway in maize (Zea mays L.). pathway activation by effector-receptor interaction. Biochemistry 2013; 52:9129-40. [PMID: 24358933 DOI: 10.1021/bi401474x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The primordial TOR pathway, known to control growth and cell proliferation, has still not been fully described for plants. Nevertheless, in maize, an insulin-like growth factor (ZmIGF) peptide has been reported to stimulate this pathway. This research provides further insight into the TOR pathway in maize, using a biochemical approach in cultures of fast-growing (FG) and slow-growing (SG) calli, as a model system. Our results revealed that addition of either ZmIGF or insulin to SG calli stimulated DNA synthesis and increased the growth rate through cell proliferation and increased the rate of ribosomal protein (RP) synthesis by the selective mobilization of RP mRNAs into polysomes. Furthermore, analysis of the phosphorylation status of the main TOR and S6K kinases from the TOR pathway revealed stimulation by ZmIGF or insulin, whereas rapamycin inhibited its activation. Remarkably, a putative maize insulin-like receptor was recognized by a human insulin receptor antibody, as demonstrated by immunoprecipitation from membrane protein extracts of maize callus. Furthermore, competition experiments between ZmIGF and insulin for the receptor site on maize protoplasts suggested structural recognition of the putative receptor by either effector. These data were confirmed by confocal immunolocalization within the cell membrane of callus cells. Taken together, these data indicate that cell growth and cell proliferation in maize depend on the activation of the TOR-S6K pathway through the interaction of an insulin-like growth factor and its receptor. This evidence suggests that higher plants as well as metazoans have conserved this biochemical pathway to regulate their growth, supporting the conclusion that it is a highly evolved conserved pathway.
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33
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Nash A, Soheili A, Tambar UK. Stereoselective Synthesis of Functionalized Cyclic Amino Acid Derivatives via a [2,3]-Stevens Rearrangement and Ring-Closing Metathesis. Org Lett 2013; 15:4770-3. [DOI: 10.1021/ol402129h] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Aaron Nash
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, United States
| | - Arash Soheili
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, United States
| | - Uttam K. Tambar
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, United States
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34
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Ward CW, Menting JG, Lawrence MC. The insulin receptor changes conformation in unforeseen ways on ligand binding: Sharpening the picture of insulin receptor activation. Bioessays 2013; 35:945-54, doi/10.1002/bies.201370111. [DOI: 10.1002/bies.201300065] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Colin W. Ward
- Walter and Eliza Hall Institute of Medical Research; Parkville Victoria Australia
| | - John G. Menting
- Walter and Eliza Hall Institute of Medical Research; Parkville Victoria Australia
| | - Michael C. Lawrence
- Walter and Eliza Hall Institute of Medical Research; Parkville Victoria Australia
- Department of Medical Biology; University of Melbourne; Parkville Victoria Australia
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35
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Žáková L, Kletvíková E, Veverka V, Lepsík M, Watson CJ, Turkenburg JP, Jirácek J, Brzozowski AM. Structural integrity of the B24 site in human insulin is important for hormone functionality. J Biol Chem 2013; 288:10230-40. [PMID: 23447530 DOI: 10.1074/jbc.m112.448050] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite the recent first structural insight into the insulin-insulin receptor complex, the role of the C terminus of the B-chain of insulin in this assembly remains unresolved. Previous studies have suggested that this part of insulin must rearrange to reveal amino acids crucial for interaction with the receptor. The role of the invariant Phe(B24), one of the key residues of the hormone, in this process remains unclear. For example, the B24 site functionally tolerates substitutions to D-amino acids but not to L-amino acids. Here, we prepared and characterized a series of B24-modified insulin analogues, also determining the structures of [D-HisB24]-insulin and [HisB24]-insulin. The inactive [HisB24]-insulin molecule is remarkably rigid due to a tight accommodation of the L-His side chain in the B24 binding pocket that results in the stronger tethering of B25-B28 residues to the protein core. In contrast, the highly active [D-HisB24]-insulin is more flexible, and the reverse chirality of the B24C(α) atom swayed the D-His(B24) side chain into the solvent. Furthermore, the pocket vacated by Phe(B24) is filled by Phe(B25), which mimics the Phe(B24) side and main chains. The B25→B24 downshift results in a subsequent downshift of Tyr(B26) into the B25 site and the departure of B26-B30 residues away from the insulin core. Our data indicate the importance of the aromatic L-amino acid at the B24 site and the structural invariance/integrity of this position for an effective binding of insulin to its receptor. Moreover, they also suggest limited, B25-B30 only, unfolding of the C terminus of the B-chain upon insulin activation.
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Affiliation(s)
- Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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36
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Vashisth H, Abrams CF. All-atom structural models of insulin binding to the insulin receptor in the presence of a tandem hormone-binding element. Proteins 2013; 81:1017-30. [PMID: 23348915 DOI: 10.1002/prot.24255] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 12/11/2012] [Accepted: 01/04/2013] [Indexed: 11/10/2022]
Abstract
Insulin regulates blood glucose levels in higher organisms by binding to and activating insulin receptor (IR), a constitutively homodimeric glycoprotein of the receptor tyrosine kinase (RTK) superfamily. Therapeutic efforts in treating diabetes have been significantly impeded by the absence of structural information on the activated form of the insulin/IR complex. Mutagenesis and photo-crosslinking experiments and structural information on insulin and apo-IR strongly suggest that the dual-chain insulin molecule, unlike the related single-chain insulin-like growth factors, binds to IR in a very different conformation than what is displayed in storage forms of the hormone. In particular, hydrophobic residues buried in the core of the folded insulin molecule engage the receptor. There is also the possibility of plasticity in the receptor structure based on these data, which may in part be due to rearrangement of the so-called CT-peptide, a tandem hormone-binding element of IR. These possibilities provide opportunity for large-scale molecular modeling to contribute to our understanding of this system. Using various atomistic simulation approaches, we have constructed all-atom structural models of hormone/receptor complexes in the presence of CT in its crystallographic position and a thermodynamically favorable displaced position. In the "displaced-CT" complex, many more insulin-receptor contacts suggested by experiments are satisfied, and our simulations also suggest that R-insulin potentially represents the receptor-bound form of hormone. The results presented in this work have further implications for the design of receptor-specific agonists/antagonists.
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Affiliation(s)
- Harish Vashisth
- Department of Chemistry and Biophysics Program, University of Michigan, Ann Arbor, Michigan, USA.
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37
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Menting JG, Whittaker J, Margetts MB, Whittaker LJ, Kong GKW, Smith BJ, Watson CJ, Záková L, Kletvíková E, Jiráček J, Chan SJ, Steiner DF, Dodson GG, Brzozowski AM, Weiss MA, Ward CW, Lawrence MC. How insulin engages its primary binding site on the insulin receptor. Nature 2013; 493:241-5. [PMID: 23302862 DOI: 10.1038/nature11781] [Citation(s) in RCA: 287] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/12/2012] [Indexed: 12/24/2022]
Abstract
Insulin receptor signalling has a central role in mammalian biology, regulating cellular metabolism, growth, division, differentiation and survival. Insulin resistance contributes to the pathogenesis of type 2 diabetes mellitus and the onset of Alzheimer's disease; aberrant signalling occurs in diverse cancers, exacerbated by cross-talk with the homologous type 1 insulin-like growth factor receptor (IGF1R). Despite more than three decades of investigation, the three-dimensional structure of the insulin-insulin receptor complex has proved elusive, confounded by the complexity of producing the receptor protein. Here we present the first view, to our knowledge, of the interaction of insulin with its primary binding site on the insulin receptor, on the basis of four crystal structures of insulin bound to truncated insulin receptor constructs. The direct interaction of insulin with the first leucine-rich-repeat domain (L1) of insulin receptor is seen to be sparse, the hormone instead engaging the insulin receptor carboxy-terminal α-chain (αCT) segment, which is itself remodelled on the face of L1 upon insulin binding. Contact between insulin and L1 is restricted to insulin B-chain residues. The αCT segment displaces the B-chain C-terminal β-strand away from the hormone core, revealing the mechanism of a long-proposed conformational switch in insulin upon receptor engagement. This mode of hormone-receptor recognition is novel within the broader family of receptor tyrosine kinases. We support these findings by photo-crosslinking data that place the suggested interactions into the context of the holoreceptor and by isothermal titration calorimetry data that dissect the hormone-insulin receptor interface. Together, our findings provide an explanation for a wealth of biochemical data from the insulin receptor and IGF1R systems relevant to the design of therapeutic insulin analogues.
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Affiliation(s)
- John G Menting
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
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38
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On the use of size exclusion chromatography for the resolution of mixed amyloid aggregate distributions: I. Equilibrium partition models. Anal Biochem 2012; 426:69-85. [DOI: 10.1016/j.ab.2012.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/30/2012] [Accepted: 04/01/2012] [Indexed: 11/24/2022]
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39
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Morcavallo A, Genua M, Palummo A, Kletvikova E, Jiracek J, Brzozowski AM, Iozzo RV, Belfiore A, Morrione A. Insulin and insulin-like growth factor II differentially regulate endocytic sorting and stability of insulin receptor isoform A. J Biol Chem 2012; 287:11422-36. [PMID: 22318726 DOI: 10.1074/jbc.m111.252478] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The insulin receptor isoform A (IR-A) binds both insulin and insulin-like growth factor (IGF)-II, although the affinity for IGF-II is 3-10-fold lower than insulin depending on a cell and tissue context. Notably, in mouse embryonic fibroblasts lacking the IGF-IR and expressing solely the IR-A (R-/IR-A), IGF-II is a more potent mitogen than insulin. As receptor endocytosis and degradation provide spatial and temporal regulation of signaling events, we hypothesized that insulin and IGF-II could affect IR-A biological responses by differentially regulating IR-A trafficking. Using R-/IR-A cells, we discovered that insulin evoked significant IR-A internalization, a process modestly affected by IGF-II. However, the differential internalization was not due to IR-A ubiquitination. Notably, prolonged stimulation of R-/IR-A cells with insulin, but not with IGF-II, targeted the receptor to a degradative pathway. Similarly, the docking protein insulin receptor substrate 1 (IRS-1) was down-regulated after prolonged insulin but not IGF-II exposure. Similar results were also obtained in experiments using [NMeTyr(B26)]-insulin, an insulin analog with IR-A binding affinity similar to IGF-II. Finally, we discovered that IR-A was internalized through clathrin-dependent and -independent pathways, which differentially regulated the activation of downstream effectors. Collectively, our results suggest that a lower affinity of IGF-II for the IR-A promotes lower IR-A phosphorylation and activation of early downstream effectors vis à vis insulin but may protect IR-A and IRS-1 from down-regulation thereby evoking sustained and robust mitogenic stimuli.
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Affiliation(s)
- Alaide Morcavallo
- Department of Urology and Endocrine Mechanisms and Hormone Action Program, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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40
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Antolíková E, Žáková L, Turkenburg JP, Watson CJ, Hančlová I, Šanda M, Cooper A, Kraus T, Brzozowski AM, Jiráček J. Non-equivalent role of inter- and intramolecular hydrogen bonds in the insulin dimer interface. J Biol Chem 2011; 286:36968-77. [PMID: 21880708 PMCID: PMC3196076 DOI: 10.1074/jbc.m111.265249] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/03/2011] [Indexed: 11/06/2022] Open
Abstract
Apart from its role in insulin receptor (IR) activation, the C terminus of the B-chain of insulin is also responsible for the formation of insulin dimers. The dimerization of insulin plays an important role in the endogenous delivery of the hormone and in the administration of insulin to patients. Here, we investigated insulin analogues with selective N-methylations of peptide bond amides at positions B24, B25, or B26 to delineate their structural and functional contribution to the dimer interface. All N-methylated analogues showed impaired binding affinities to IR, which suggests a direct IR-interacting role for the respective amide hydrogens. The dimerization capabilities of analogues were investigated by isothermal microcalorimetry. Selective N-methylations of B24, B25, or B26 amides resulted in reduced dimerization abilities compared with native insulin (K(d) = 8.8 μM). Interestingly, although the N-methylation in [NMeTyrB26]-insulin or [NMePheB24]-insulin resulted in K(d) values of 142 and 587 μM, respectively, the [NMePheB25]-insulin did not form dimers even at high concentrations. This effect may be attributed to the loss of intramolecular hydrogen bonding between NHB25 and COA19, which connects the B-chain β-strand to the core of the molecule. The release of the B-chain β-strand from this hydrogen bond lock may result in its higher mobility, thereby shifting solution equilibrium toward the monomeric state of the hormone. The study was complemented by analyses of two novel analogue crystal structures. All examined analogues crystallized only in the most stable R(6) form of insulin oligomers (even if the dimer interface was totally disrupted), confirming the role of R(6)-specific intra/intermolecular interactions for hexamer stability.
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Affiliation(s)
- Emília Antolíková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Johan P. Turkenburg
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Christopher J. Watson
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Ivona Hančlová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Miloslav Šanda
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Alan Cooper
- the School of Chemistry, Glasgow University, College of Science and Engineering, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Tomáš Kraus
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - A. Marek Brzozowski
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Jiří Jiráček
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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41
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Biochemical contacts and collaborations between China and the U.K. since 1911. Biochem Soc Trans 2011; 39:1313-22. [DOI: 10.1042/bst0391313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Scientific contact lies at the heart of research and that between China and the U.K. is an important example of how it can come about. In 1911, when the Biochemical Society began, U.K. science was developing fast with profound discoveries in physics (the Rutherford atomic model) and biochemistry (the discovery of vitamins). In China, however, there was great social and political instability and a revolution. Since then, the turbulence of two world wars and a variety of deep global political tensions meant that the contacts between China and U.K. did not reflect the prodigious growth of biochemistry. There was, however, one particular and remarkable contact, that made by Joseph Needham, an outstanding biochemist. He visited China between 1943 and 1946, contacting many Chinese universities that were severely dislocated by war. Showing remarkable diplomatic abilities, Needham managed to arrange delivery of research and teaching equipment. His activities helped the universities to carry out their functions under near-impossible conditions and reminded them that they had friends abroad. Most remarkably, Joseph Needham developed an extraordinary grasp of Chinese culture, science and history and he opened the West to the extent and importance of Chinese science. Formal scientific and intellectual contacts between the scientific academic bodies in China and U.K., notably the Chinese Academy of Science and the Royal Society, resumed after British recognition of the Chinese Communist government in 1950. The delegations included outstanding scientists in biochemistry and related disciplines. Research activities, such as that concerning influenza, were soon established, whereas institutions, such as the Royal Society and the Wellcome Trust, acted a little later to support research. The outcomes have been long-term collaborations in such areas as insulin structure and function. There are now numerous joint activities in biochemistry and biomedicine supported by the MRC (Medical Research Council), BBSRC (Biotechnology and Biological Sciences Research Council), NERC (Natural Environment Research Council), EPSRC (Engineering and Physical Sciences Research Council) and UKRC (UK Research Councils). The present contacts and the associated research are very considerable and growing. It is clear that biochemistry in both countries has much to offer each other, and there is every reason to believe that these contacts will continue to expand in the future.
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Abstract
The widespread epidemic of obesity and type 2 diabetes has raised concern for the impact of these disorders as risk factors for cancer and has renewed the interest for studies regarding the involvement of hyperinsulinemia and insulin receptor (IR) in cancer progression. Overexpression of IR in cancer cells may explain their increased sensitivity to hyperinsulinemia. Moreover, IR isoform A (IR-A) together with autocrine production of its ligand IGF2 is emerging as an important mechanism of normal and cancer stem cell expansion and is a feature of several malignancies. De novo activation of the IR-A/IGF2 autocrine loop also represents a mechanism of resistance to anticancer therapies. Increasing knowledge of the IR role in cancer has important implications for cancer prevention, which should include control of insulin resistance and hyperinsulinemia in the population and meticulous evaluation of new antidiabetic drugs for their metabolic:mitogenic ratio. We are now aware that several anticancer treatments may induce or worsen insulin resistance that may limit therapy efficacy. Future anticancer therapies need to target the IR-A pathway in order to inhibit the tumor promoting effect of IR without impairing the metabolic effect of insulin.
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Affiliation(s)
- Antonino Belfiore
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Campus Universitario, località Germaneto, 88100 Catanzaro, Italy.
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43
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Malaguarnera R, Belfiore A. The insulin receptor: a new target for cancer therapy. Front Endocrinol (Lausanne) 2011; 2:93. [PMID: 22654833 PMCID: PMC3356071 DOI: 10.3389/fendo.2011.00093] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 11/19/2011] [Indexed: 12/16/2022] Open
Abstract
A large body of evidences have shown that both the IGF-I receptor (IGF-IR) and the insulin receptor (IR) play a role in cancer development and progression. In particular, IR overactivation by IGF-II is common in cancer cells, especially in dedifferentiated/stem-like cells. In spite of these findings, until very recently, only IGF-IR but not IR has been considered a target in cancer therapy. Although several preclinical studies have showed a good anti-cancer activity of selective anti-IGF-IR drugs, the results of the clinical first trials have been disappointing. In fact, only a small subset of malignant tumors has shown an objective response to these therapies. Development of resistance to anti-IGF-IR drugs may include upregulation of IR isoform A (IR-A) in cancer cells and its overactivation by increased secretion of autocrine IGF-II. These findings have led to the concept that co-targeting IR together with IGF-IR may increase therapy efficacy and prevent adaptive resistance to selective anti-IGF-IR drugs. IR blockade should be especially considered in tumors with high IR-A:IGF-IR ratio and high levels of autocrine IGF-II. Conversely, insulin sensitizers, which ameliorate insulin resistance associated with metabolic disorders and cancer treatments, may have important implications for cancer prevention and management. Only few drugs co-targeting the IR and IGF-IR are currently available. Ideally, future IR targeting strategies should be able to selectively inhibit the tumor promoting effects of IR without impairing its metabolic effects.
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Affiliation(s)
- Roberta Malaguarnera
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University Magna Graecia of CatanzaroCatanzaro, Italy
| | - Antonino Belfiore
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University Magna Graecia of CatanzaroCatanzaro, Italy
- *Correspondence: Antonino Belfiore, Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Catanzaro, Campus Universitario, Viale Europa, località Germaneto, 88100 Catanzaro, Italy. e-mail:
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Abstract
Ever since the discovery of insulin and its role in the regulation of glucose uptake and utilization, there has been great interest in insulin, its structure and the way in which it interacts with its receptor and effects signal transduction. As the 90th anniversary of the discovery of insulin approaches, it is timely to provide an overview of the landmark discoveries relating to the structure and function of this remarkable molecule and its receptor.
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Affiliation(s)
- Colin W. Ward
- Walter and Eliza Hall Institute of Medical ResearchParkville, VIC, Australia
| | - Michael C. Lawrence
- Walter and Eliza Hall Institute of Medical ResearchParkville, VIC, Australia
- Department of Medical Biology, University of MelbourneParkville, VIC, Australia
- *Correspondence: Michael C. Lawrence, Walter and Eliza Hall Institute, 1G Royal Parade, Parkville, VIC 3052, Australia. e-mail:
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45
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Structural resolution of a tandem hormone-binding element in the insulin receptor and its implications for design of peptide agonists. Proc Natl Acad Sci U S A 2010; 107:6771-6. [PMID: 20348418 DOI: 10.1073/pnas.1001813107] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The C-terminal segment of the human insulin receptor alpha-chain (designated alphaCT) is critical to insulin binding as has been previously demonstrated by alanine scanning mutagenesis and photo-cross-linking. To date no information regarding the structure of this segment within the receptor has been available. We employ here the technique of thermal-factor sharpening to enhance the interpretability of the electron-density maps associated with the earlier crystal structure of the human insulin receptor ectodomain. The alphaCT segment is now resolved as being engaged with the central beta-sheet of the first leucine-rich repeat (L1) domain of the receptor. The segment is alpha-helical in conformation and extends 11 residues N-terminal of the classical alphaCT segment boundary originally defined by peptide mapping. This tandem structural element (alphaCT-L1) thus defines the intact primary insulin-binding surface of the apo-receptor. The structure, together with isothermal titration calorimetry data of mutant alphaCT peptides binding to an insulin minireceptor, leads to the conclusion that putative "insulin-mimetic" peptides in the literature act at least in part as mimics of the alphaCT segment as well as of insulin. Photo-cross-linking by novel bifunctional insulin derivatives demonstrates that the interaction of insulin with the alphaCT segment and the L1 domain occurs in trans, i.e., these components of the primary binding site are contributed by alternate alpha-chains within the insulin receptor homodimer. The tandem structural element defines a new target for the design of insulin agonists for the treatment of diabetes mellitus.
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