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Abstract
Insulin is a peptide hormone essential for maintaining normal blood glucose levels. Individuals unable to secrete sufficient insulin or not able to respond properly to insulin develop diabetes. Since the discovery of insulin its structure and function has been intensively studied with the aim to develop effective diabetes treatments. The three-dimensional crystal structure of this 51 amino acid peptide paved the way for discoveries, outlined in this review, of determinants important for receptor binding and hormone stability that have been instrumental in development of insulin analogs used in the clinic today. Important for the future development of effective diabetes treatments will be a detailed understanding of the insulin receptor structure and function. Determination of the three-dimensional structure of the insulin receptor, a receptor tyrosine kinase, proved challenging but with the recent advent of high-resolution cryo-electron microscopy significant progress has been made. There are now >40 structures of the insulin:insulin receptor complex deposited in the Protein Data Bank. From these structures we have a detailed picture of how insulin binds and activates the receptor. Still lacking are details of the initial binding events and the exact sequence of structural changes within the receptor and insulin. In this review, the focus will be on the most recent structural studies of insulin:insulin receptor complexes and how they have contributed to the current understanding of insulin receptor activation and signaling outcome. Molecular mechanisms underlying insulin receptor signaling bias emerging from the latest structures are described.
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Affiliation(s)
- Briony E Forbes
- Flinders Health and Medical Research Institute, Flinders University, Bedford Park, SA, Australia.
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De Meyts P. [The insulin receptor discovery is 50 years old - A review of achieved progress]. Biol Aujourdhui 2022; 216:7-28. [PMID: 35876517 DOI: 10.1051/jbio/2022007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Indexed: 06/15/2023]
Abstract
The isolation of insulin from the pancreas and its purification to a degree permitting its safe administration to type 1 diabetic patients were accomplished 100 years ago at the University of Toronto by Banting, Best, Collip and McLeod and constitute undeniably one of the major medical therapeutic revolutions, recognized by the attribution of the 1923 Nobel Prize in Physiology or Medicine to Banting and McLeod. The clinical spin off was immediate as well as the internationalization of insulin's commercial production. The outcomes regarding basic research were much slower, in particular regarding the molecular mechanisms of insulin action on its target cells. It took almost a half-century before the determination of the tri-dimensional structure of insulin in 1969 and the characterization of its cell receptor in 1970-1971. The demonstration that the insulin receptor is in fact an enzyme named tyrosine kinase came in the years 1982-1985, and the crystal structure of the intracellular kinase domain 10 years later. The crystal structure of the first intracellular kinase substrate (IRS-1) in 1991 paved the way for the elucidation of the intracellular signalling pathways but it took 15 more years to obtain the complete crystal structure of the extracellular receptor domain (without insulin) in 2006. Since then, the determination of the structure of the whole insulin-receptor complex in both the inactive and activated states has made considerable progress, not least due to recent improvement in the resolution power of cryo-electron microscopy. I will here review the steps in the development of the concept of hormone receptor, and of our knowledge of the structure and molecular mechanism of activation of the insulin receptor.
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Affiliation(s)
- Pierre De Meyts
- de Duve Institute, Department of Cell Signalling, Avenue Hippocrate 74, B-1200 Bruxelles, Belgique - Novo Nordisk A/S, Department of Stem Cell Research, Novo Nordisk Park 1, DK-2760 Maaloev, Danemark
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Nielsen J, Brandt J, Boesen T, Hummelshøj T, Slaaby R, Schluckebier G, Nissen P. Structural investigations of full-length insulin receptor dynamics and signalling. J Mol Biol 2022; 434:167458. [DOI: 10.1016/j.jmb.2022.167458] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/28/2021] [Accepted: 01/14/2022] [Indexed: 12/21/2022]
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Følling I, Wennerstrøm AB, Eide TJ, Nilsen HL. Phaeochromocytomas overexpress insulin transcript and produce insulin. Endocr Connect 2021; 10:815-824. [PMID: 34170845 PMCID: PMC8346199 DOI: 10.1530/ec-21-0269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 06/25/2021] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Phaeochromocytomas are tumours originating in the medulla of the adrenal gland. They produce catecholamines, and some tumours also produce ectopic hormones. Two types of glucose imbalances occur in phaeochromocytoma patients, hyperglycaemia and hypoglycaemic attacks. Therefore, we tested whether insulin transcript (INS), insulin, and a hybrid read-through transcript between exons from insulin and insulin-like growth factor 2 (INS-IGF2) were expressed in phaeochromocytomas. METHODS We measured the expression of insulin using immunohistochemistry. The expression of INS-IGF2 was determined by qRT-PCR in formalin-fixed and paraffin-embedded tissue from 20 phaeochromocytomas. The expression of INS and INS-IGF2 transcriptswas also analysed in 182 phaeochromocytomas and paragangliomas using publicly available datasets in The Cancer Genome Atlas (TCGA) Database. RESULTS Of 20 phaeochromocytomas, 16 stained positive for insulin. The distribution of positive cells was mostly scattered, with some focal expression indicating clonal expansion. Nineteen tumours expressed high levels of INS and INS-IGF2 transcripts. The expression of the two transcripts corresponded closely. In the TCGA dataset, phaeochromocytoma expresses higher levels of INS and INS-IGF2 transcripts compared to the normal non-tumour adrenal glands. Thus, the expression of INS and INS-IGF2 seems to be a general phenomenon in phaeochromocytoma. CONCLUSION Most phaeochromocytomas contain cells that overexpress INS and INS-IGF2 transcripts. Most tumours also display heterogeneous expression of polypeptides immunoreactive to monoclonal anti-insulin antibodies. Clinically this may relate to both hyperglycaemia and hypoglycaemic attacks seen in patients with phaeochromocytoma as well as autocrine tumour growth.
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Affiliation(s)
- Ivar Følling
- Department of Endocrinology, Akershus University Hospital, Lørenskog, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
- Correspondence should be addressed to I Følling:
| | - Anna B Wennerstrøm
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Tor J Eide
- Division of Laboratory Medicine, Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Hilde Loge Nilsen
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
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Quasi-Steady-State Analysis based on Structural Modules and Timed Petri Net Predict System's Dynamics: The Life Cycle of the Insulin Receptor. Metabolites 2015; 5:766-93. [PMID: 26694479 PMCID: PMC4693194 DOI: 10.3390/metabo5040766] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/23/2015] [Accepted: 12/09/2015] [Indexed: 02/01/2023] Open
Abstract
The insulin-dependent activation and recycling of the insulin receptor play an essential role in the regulation of the energy metabolism, leading to a special interest for pharmaceutical applications. Thus, the recycling of the insulin receptor has been intensively investigated, experimentally as well as theoretically. We developed a time-resolved, discrete model to describe stochastic dynamics and study the approximation of non-linear dynamics in the context of timed Petri nets. Additionally, using a graph-theoretical approach, we analyzed the structure of the regulatory system and demonstrated the close interrelation of structural network properties with the kinetic behavior. The transition invariants decomposed the model into overlapping subnetworks of various sizes, which represent basic functional modules. Moreover, we computed the quasi-steady states of these subnetworks and demonstrated that they are fundamental to understand the dynamic behavior of the system. The Petri net approach confirms the experimental results of insulin-stimulated degradation of the insulin receptor, which represents a common feature of insulin-resistant, hyperinsulinaemic states.
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Tatulian SA. Structural Dynamics of Insulin Receptor and Transmembrane Signaling. Biochemistry 2015; 54:5523-32. [PMID: 26322622 DOI: 10.1021/acs.biochem.5b00805] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The insulin receptor (IR) is a (αβ)2-type transmembrane tyrosine kinase that plays a central role in cell metabolism. Each αβ heterodimer consists of an extracellular ligand-binding α-subunit and a membrane-spanning β-subunit that comprises the cytoplasmic tyrosine kinase (TK) domain and the phosphorylation sites. The α- and β-subunits are linked via a single disulfide bridge, and the (αβ)2 tetramer is formed by disulfide bonds between the α-chains. Insulin binding induces conformational changes in IR that reach the intracellular β-subunit followed by a protein phosphorylation and activation cascade. Defects in this signaling process, including IR dysfunction caused by mutations, result in type 2 diabetes. Rational drug design aimed at treatment of diabetes relies on knowledge of the detailed structure of IR and the dynamic structural transformations during transmembrane signaling. Recent X-ray crystallographic studies have provided important clues about the mode of binding of insulin to IR, the resulting structural changes and their transmission to the TK domain, but a complete understanding of the structural basis underlying insulin signaling has not been achieved. This review presents a critical analysis of the current status of the structure-function relationship of IR, with a comparative assessment of the other IR family receptors, and discusses potential advancements that may provide insight into the molecular mechanism of insulin signaling.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida , 4111 Libra Drive, Orlando, Florida 32816, United States
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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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Guzmán-Gutiérrez E, Arroyo P, Salsoso R, Fuenzalida B, Sáez T, Leiva A, Pardo F, Sobrevia L. Role of Insulin and Adenosine in the Human Placenta Microvascular and Macrovascular Endothelial Cell Dysfunction in Gestational Diabetes Mellitus. Microcirculation 2014; 21:26-37. [DOI: 10.1111/micc.12077] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/18/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Enrique Guzmán-Gutiérrez
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Pablo Arroyo
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Rocío Salsoso
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Bárbara Fuenzalida
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
- Biomedical Department; Faculty of Health Sciences; Universidad de Antofagasta; Antofagasta Chile
| | - Tamara Sáez
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Andrea Leiva
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Fabián Pardo
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
- University of Queensland Centre for Clinical Research; Herston Queensland Australia
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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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Vinther TN, Norrman M, Strauss HM, Huus K, Schlein M, Pedersen TÅ, Kjeldsen T, Jensen KJ, Hubálek F. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization. PLoS One 2012; 7:e30882. [PMID: 22363506 PMCID: PMC3281904 DOI: 10.1371/journal.pone.0030882] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 12/23/2011] [Indexed: 11/18/2022] Open
Abstract
An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers in the circulation, and it is stabilized by hexamer formation in the presence of zinc ions during storage in the pancreatic β-cell. Due to the transient nature of insulin dimer, direct investigation of this important form is inherently difficult. To address the relationship between insulin oligomerization and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization to form the structural equivalent of the classical hexamer. The covalently linked dimer neither bound to the insulin receptor, nor induced a metabolic response in vitro. However, it was extremely thermodynamically stable and did not form amyloid fibrils when subjected to mechanical stress, underlining the importance of oligomerization for insulin stability.
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Affiliation(s)
- Tine N. Vinther
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
- Faculty of Life Sciences, IGM, University of Copenhagen, Frederiksberg, Denmark
| | - Mathias Norrman
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Holger M. Strauss
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Kasper Huus
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Morten Schlein
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Thomas Å. Pedersen
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Thomas Kjeldsen
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Knud J. Jensen
- Faculty of Life Sciences, IGM, University of Copenhagen, Frederiksberg, Denmark
| | - František Hubálek
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
- * E-mail:
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