1
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Joshi O, Skóra T, Yarema A, Rabbitt RD, Bidone TC. Contributions of the individual domains of α IIbβ 3 integrin to its extension: Insights from multiscale modeling. Cytoskeleton (Hoboken) 2024; 81:393-408. [PMID: 38682753 PMCID: PMC11333186 DOI: 10.1002/cm.21865] [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: 11/14/2023] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 05/01/2024]
Abstract
The platelet integrin αIIbβ3 undergoes long-range conformational transitions between bent and extended conformations to regulate platelet aggregation during hemostasis and thrombosis. However, how exactly αIIbβ3 transitions between conformations remains largely elusive. Here, we studied how transitions across bent and extended-closed conformations of αIIbβ3 integrin are regulated by effective interactions between its functional domains. We first carried out μs-long equilibrium molecular dynamics (MD) simulations of full-length αIIbβ3 integrins in bent and intermediate conformations, the latter characterized by an extended headpiece and closed legs. Then, we built heterogeneous elastic network models, perturbed inter-domain interactions, and evaluated their relative contributions to the energy barriers between conformations. Results showed that integrin extension emerges from: (i) changes in interfaces between functional domains; (ii) allosteric coupling of the head and upper leg domains with flexible lower leg domains. Collectively, these results provide new insights into integrin conformational activation based on short- and long-range interactions between its functional domains and highlight the importance of the lower legs in the regulation of integrin allostery.
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Affiliation(s)
- Onkar Joshi
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA
| | - Tomasz Skóra
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA
| | - Anna Yarema
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Richard D Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Tamara C Bidone
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA
- Department of Molecular Pharmaceutics, University of Utah, Salt Lake City, Utah, USA
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, USA
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2
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Gaikwad HK, Jaswandkar SV, Katti KS, Haage A, Katti DR. Molecular basis of conformational changes and mechanics of integrins. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220243. [PMID: 37211038 DOI: 10.1098/rsta.2022.0243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 01/13/2023] [Indexed: 05/23/2023]
Abstract
Integrin, as a mechanotransducer, establishes the mechanical reciprocity between the extracellular matrix (ECM) and cells at integrin-mediated adhesion sites. This study used steered molecular dynamics (SMD) simulations to investigate the mechanical responses of integrin αvβ3 with and without 10th type III fibronectin (FnIII10) binding for tensile, bending and torsional loading conditions. The ligand-binding integrin confirmed the integrin activation during equilibration and altered the integrin dynamics by changing the interface interaction between β-tail, hybrid and epidermal growth factor domains during initial tensile loading. The tensile deformation in integrin molecules indicated that fibronectin ligand binding modulates its mechanical responses in the folded and unfolded conformation states. The bending deformation responses of extended integrin models reveal the change in behaviour of integrin molecules in the presence of Mn2+ ion and ligand based on the application of force in the folding and unfolding directions of integrin. Furthermore, these SMD simulation results were used to predict the mechanical properties of integrin underlying the mechanism of integrin-based adhesion. The evaluation of integrin mechanics provides new insights into understanding the mechanotransmission (force transmission) between cells and ECM and contributes to developing an accurate model for integrin-mediated adhesion. This article is part of a discussion meeting issue 'Supercomputing simulations of advanced materials'.
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Affiliation(s)
- Hanmant K Gaikwad
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, ND 58105, USA
| | - Sharad V Jaswandkar
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, ND 58105, USA
| | - Kalpana S Katti
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, ND 58105, USA
| | - Amanda Haage
- Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Dinesh R Katti
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, ND 58105, USA
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3
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Masaike S, Tsuji Y, Kidoaki S. Local pH mapping in the cell adhesion nano-interfaces on a pH-responsive fluorescence-dye-immobilized substrate. ANAL SCI 2023; 39:347-355. [PMID: 36564615 DOI: 10.1007/s44211-022-00239-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/10/2022] [Indexed: 12/24/2022]
Abstract
Cell-substrate adhesion nano-interfaces can, in principle, exhibit a spatial distribution of local pH values under the influence of the weakly acidic microenvironment of glycocalyx grafted on lipid bilayer cell membrane which is compressed and closely attached to culture substrate in the vicinity of integrin-adhesion complexes. However, a simple local pH distribution imaging methodology has not been developed. In this study, to visualize the local pH distribution at the cell adhesion interface, we prepared glass substrates chemically modified with a pH-responsive fluorescent dye fluorescein isothiocyanate (FITC), observed the distribution of FITC fluorescence intensity at the adhesion interface of fibroblast (NIH/3T3) and cancer cells (HeLa), and compared the FITC images with the observed distribution of focal adhesions. FITC images were converted to pH mapping based on the pH-fluorescence calibration data of surface-immobilized FITC pre-measured in different pH media, which showed significantly larger regions with lowered pH level (6.8-7.0) from outside the cell (pH 7.4) were observed at the thick inner periphery of HeLa cells while 3T3 cells exhibited smaller lowered pH regions at the thin periphery. The lowered pH regions overlapped with many focal adhesions, and image analysis showed that larger focal adhesions tend to possess more lowered pH sites inside, reflecting enhanced glycocalyx compression due to accumulated integrin-adhesion ligand binding. This tendency was stronger for HeLa than for 3T3 cells. The role of glycocalyx compression and the pH reduction at the cell adhesive interface is discussed.
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Affiliation(s)
- Sayaka Masaike
- Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | - Yukie Tsuji
- Laboratory of Biomedical and Biophysical Chemistry, Institute for Materials Chemistry and Engineering, Kyushu University, CE41-204, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan
| | - Satoru Kidoaki
- Laboratory of Biomedical and Biophysical Chemistry, Institute for Materials Chemistry and Engineering, Kyushu University, CE41-204, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
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4
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Tvaroška I, Kozmon S, Kóňa J. Molecular Modeling Insights into the Structure and Behavior of Integrins: A Review. Cells 2023; 12:cells12020324. [PMID: 36672259 PMCID: PMC9856412 DOI: 10.3390/cells12020324] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Integrins are heterodimeric glycoproteins crucial to the physiology and pathology of many biological functions. As adhesion molecules, they mediate immune cell trafficking, migration, and immunological synapse formation during inflammation and cancer. The recognition of the vital roles of integrins in various diseases revealed their therapeutic potential. Despite the great effort in the last thirty years, up to now, only seven integrin-based drugs have entered the market. Recent progress in deciphering integrin functions, signaling, and interactions with ligands, along with advancement in rational drug design strategies, provide an opportunity to exploit their therapeutic potential and discover novel agents. This review will discuss the molecular modeling methods used in determining integrins' dynamic properties and in providing information toward understanding their properties and function at the atomic level. Then, we will survey the relevant contributions and the current understanding of integrin structure, activation, the binding of essential ligands, and the role of molecular modeling methods in the rational design of antagonists. We will emphasize the role played by molecular modeling methods in progress in these areas and the designing of integrin antagonists.
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Affiliation(s)
- Igor Tvaroška
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Correspondence:
| | - Stanislav Kozmon
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Medical Vision o. z., Záhradnícka 4837/55, 821 08 Bratislava, Slovakia
| | - Juraj Kóňa
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia
- Medical Vision o. z., Záhradnícka 4837/55, 821 08 Bratislava, Slovakia
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5
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Integrin Conformational Dynamics and Mechanotransduction. Cells 2022; 11:cells11223584. [PMID: 36429013 PMCID: PMC9688440 DOI: 10.3390/cells11223584] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
The function of the integrin family of receptors as central mediators of cell-extracellular matrix (ECM) and cell-cell adhesion requires a remarkable convergence of interactions and influences. Integrins must be anchored to the cytoskeleton and bound to extracellular ligands in order to provide firm adhesion, with force transmission across this linkage conferring tissue integrity. Integrin affinity to ligands is highly regulated by cell signaling pathways, altering affinity constants by 1000-fold or more, via a series of long-range conformational transitions. In this review, we first summarize basic, well-known features of integrin conformational states and then focus on new information concerning the impact of mechanical forces on these states and interstate transitions. We also discuss how these effects may impact mechansensitive cell functions and identify unanswered questions for future studies.
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6
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Lin FY, Li J, Xie Y, Zhu J, Huong Nguyen TT, Zhang Y, Zhu J, Springer TA. A general chemical principle for creating closure-stabilizing integrin inhibitors. Cell 2022; 185:3533-3550.e27. [PMID: 36113427 PMCID: PMC9494814 DOI: 10.1016/j.cell.2022.08.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/07/2022] [Accepted: 08/04/2022] [Indexed: 01/26/2023]
Abstract
Integrins are validated drug targets with six approved therapeutics. However, small-molecule inhibitors to three integrins failed in late-stage clinical trials for chronic indications. Such unfavorable outcomes may in part be caused by partial agonism, i.e., the stabilization of the high-affinity, extended-open integrin conformation. Here, we show that the failed, small-molecule inhibitors of integrins αIIbβ3 and α4β1 stabilize the high-affinity conformation. Furthermore, we discovered a simple chemical feature present in multiple αIIbβ3 antagonists that stabilizes integrins in their bent-closed conformation. Closing inhibitors contain a polar nitrogen atom that stabilizes, via hydrogen bonds, a water molecule that intervenes between a serine residue and the metal in the metal-ion-dependent adhesion site (MIDAS). Expulsion of this water is a requisite for transition to the open conformation. This change in metal coordination is general to integrins, suggesting broad applicability of the drug-design principle to the integrin family, as validated with a distantly related integrin, α4β1.
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Affiliation(s)
- Fu-Yang Lin
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jing Li
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Yonghua Xie
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, PRC
| | - Jianghai Zhu
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Thi Thu Huong Nguyen
- Blood Research Institute, Versiti, Milwaukee, WI 53226, USA; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Yonghui Zhang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, PRC.
| | - Jieqing Zhu
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Blood Research Institute, Versiti, Milwaukee, WI 53226, USA; Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | - Timothy A Springer
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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7
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Altin JG, Zhao Y. Using peptides to promote delivery and improve anti-tumour efficacy of liposomal drug. J Drug Target 2021; 30:544-556. [PMID: 34939907 DOI: 10.1080/1061186x.2021.2020799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Liposomal drugs exhibit advantages for cancer therapy, but efficacy is often limited by their rapid clearance from blood by the reticuloendothelial system, and an inability to target and penetrate tumours. Interestingly, a 21-amino acid SIRP-α- (signal regulatory protein-α) interacting 'self' peptide is reported to inhibit uptake by phagocytes. Also, 'iRGD' a 9-amino acid cyclic peptide that binds αvβ3 integrins and neuropilin-1 (NRP-1), promotes targeting and penetration of drug into tumours. Here we explore the potential of nitrilotriacetic acid-ditetra-decylamine (NTA3-DTDA)-containing liposomes (NTA-liposomes) engrafted with His-tagged forms of 'self' peptide (pCD47) to prolong circulation time in blood after iv administration, and of iRGD peptide (piRGD) to enhance treatment efficacy of doxorubicin-containing liposomes (Caelyx). Our results show that pre-incubation of murine phagocytic DC2.4 and RAW246.7 cells with pCD47 inhibits uptake of NTA-liposomes in vitro, but engraftment of pCD47 surprisingly reduces liposome lifetime in blood. Engraftment of piRGD promoted binding of NTA-liposomes to murine B16 melanoma and CT26 colorectal carcinoma cells in vitro. Importantly, iv administration of piRGD-engrafted Caelyx was found to significantly inhibit tumour growth and prolong survival in both B16 and CT26 murine tumour models. Our results show that engraftment of piRGD onto Caelyx is a convenient strategy to enhance treatment efficacy.
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Affiliation(s)
- Joseph G Altin
- Division of Biomedical Science and Biochemistry, Research School of Biology, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT, 2601, Australia
| | - Yabing Zhao
- Division of Biomedical Science and Biochemistry, Research School of Biology, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT, 2601, Australia
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8
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Huang YL, Liang CY, Labitzky V, Ritz D, Oliveira T, Cumin C, Estermann M, Lange T, Everest-Dass AV, Jacob F. Site-specific N-glycosylation of integrin α2 mediates collagen-dependent cell survival. iScience 2021; 24:103168. [PMID: 34646995 PMCID: PMC8501769 DOI: 10.1016/j.isci.2021.103168] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 07/28/2021] [Accepted: 09/21/2021] [Indexed: 11/30/2022] Open
Abstract
Integrin alpha 2 (ITGA2) promotes cancer metastasis through selective adhesion to ECM proteins; however, the specific contribution of integrin glycosylation remains uncertain. We provide evidence that ITGA2 is a highly glycosylated transmembrane protein expressed in ovarian cancer tissue and cell lines. In-depth glycoproteomics identified predominant N- and O-glycosylation sites harboring substantially divergent ITGA2 glycosylation profiles. Generated putative ITGA2 N-glycosite mutants halted collagen and laminin binding and cells lacking N-glycosylated ITGA2 were marginally adherent to collagen, likely associated with its enhanced proteasome degradation through poly-ubiquitination. Proteomic and enrichment pathway analysis revealed increased cellular apoptosis and collagen organization in non-glycosylated ITGA2 mutant cells. Moreover, we provide evidence that ITGA2-specific sialylation is involved in selective cell-ECM binding. These results highlight the importance of glycans in regulating ITGA2 stability and ligand binding capacity which in turn modulates downstream focal adhesion and promotes cell survival in a collagen environment. In-depth glycoproteomics reveal divergent ITGA2 glycosylation Site-specific N-glycans regulate protein stability and ECM ligand binding affinity Loss of N-glycosylation induces proteasome degradation through poly-ubiquitination N-glycosylation mediates collagen-dependent cell survival through focal adhesion
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Affiliation(s)
- Yen-Lin Huang
- Ovarian Cancer Research, Department of Biomedicine, University Hospital Basel and University of Basel, Hebelstrasse 20, Basel 4031, Switzerland
| | - Ching-Yeu Liang
- Ovarian Cancer Research, Department of Biomedicine, University Hospital Basel and University of Basel, Hebelstrasse 20, Basel 4031, Switzerland
| | - Vera Labitzky
- Institute of Anatomy and Experimental Morphology, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg20246, Germany
| | - Danilo Ritz
- Proteomics Core Facility, Biozentrum, University of Basel, Basel4056, Switzerland
| | - Tiago Oliveira
- Institute for Glycomics, Griffith University, Gold Coast Campus, Gold Coast, QLD4222, Australia
| | - Cécile Cumin
- Ovarian Cancer Research, Department of Biomedicine, University Hospital Basel and University of Basel, Hebelstrasse 20, Basel 4031, Switzerland
| | - Manuela Estermann
- Adolphe Merkle Institute, University of Fribourg, Fribourg1700, Switzerland
| | - Tobias Lange
- Institute of Anatomy and Experimental Morphology, University Cancer Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg20246, Germany
| | - Arun V Everest-Dass
- Institute for Glycomics, Griffith University, Gold Coast Campus, Gold Coast, QLD4222, Australia
| | - Francis Jacob
- Ovarian Cancer Research, Department of Biomedicine, University Hospital Basel and University of Basel, Hebelstrasse 20, Basel 4031, Switzerland
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9
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Sun G, Guillon E, Holley SA. Integrin intra-heterodimer affinity inversely correlates with integrin activatability. Cell Rep 2021; 35:109230. [PMID: 34107244 PMCID: PMC8227800 DOI: 10.1016/j.celrep.2021.109230] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 03/13/2021] [Accepted: 05/17/2021] [Indexed: 11/21/2022] Open
Abstract
Integrins are heterodimeric cell surface receptors composed of an α and β subunit that mediate cell adhesion to extracellular matrix proteins such as fibronectin. We previously studied integrin α5β1 activation during zebrafish somitogenesis, and in the present study, we characterize the integrin αV fibronectin receptors. Integrins are activated via a conformational change, and we perform single-molecule biophysical measurements of both integrin activation via fluorescence resonance energy transfer (FRET)-fluorescence lifetime imaging microscopy (FLIM) and integrin intra-heterodimer stability via fluorescence cross-correlation spectroscopy (FCCS) in living embryos. We find that integrin heterodimers that exhibit robust cell surface expression, including αVβ3, αVβ5, and αVβ6, are never activated in this in vivo context, even in the presence of fibronectin matrix. In contrast, activatable integrins, such as integrin αVβ1, and alleles of αVβ3, αVβ5, αVβ6 that are biased to the active conformation exhibit poor cell surface expression and have a higher intra-heterodimer dissociation constant (KD). These observations suggest that a weak integrin intra-heterodimer affinity decreases integrin cell surface stability and increases integrin activatability.
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Affiliation(s)
- Guangyu Sun
- Department of Molecular, Cellular and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, CT 06520, USA
| | - Emilie Guillon
- Department of Molecular, Cellular and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, CT 06520, USA
| | - Scott A Holley
- Department of Molecular, Cellular and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, CT 06520, USA.
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10
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Song G, Luo BH. Effects of the association of the α v β 8 lower legs on integrin ligand binding. J Cell Biochem 2021; 122:801-813. [PMID: 33619784 DOI: 10.1002/jcb.29912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/18/2022]
Abstract
Many integrins transmit signals through global conformational changes. However, it is unclear whether integrin αv β8 adopts a similar mechanism during integrin activation and signaling on the cell surface. Here, we showed that disulfide-bonded mutants, which prevented integrin αv β8 lower leg dissociation, bound ligands with similar level as the wild-type protein, suggesting that αv β8 ligand binding did not require lower leg disassociation. We further showed that the N-glycosylation mutant at the interface between the β I and hybrid domains did not affect ligand binding, suggesting that the αv β8 open headpiece was not present on the cell surface. We proposed that αv β8 integrin may adopt only one state, that is, the extended conformation with a closed headpiece. Our results showed that two lower legs retained heterodimeric interfaces, and this association might be important for stabilizing integrin in the extended conformation. Therefore, αv β8 may not transmit bidirectional signals across the plasma membrane but instead may serve as an anchoring site with high affinity and high accessibility for extracellular ligands.
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Affiliation(s)
- Guannan Song
- Department of Life Science, University of Louisiana State University, Baton Rouge, Louisiana, USA
| | - Bing-Hao Luo
- Department of Life Science, University of Louisiana State University, Baton Rouge, Louisiana, USA
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11
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Kulkarni R, Kale V. Physiological Cues Involved in the Regulation of Adhesion Mechanisms in Hematopoietic Stem Cell Fate Decision. Front Cell Dev Biol 2020; 8:611. [PMID: 32754597 PMCID: PMC7366553 DOI: 10.3389/fcell.2020.00611] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/19/2020] [Indexed: 12/16/2022] Open
Abstract
Hematopoietic stem cells (HSC) could have several fates in the body; viz. self-renewal, differentiation, migration, quiescence, and apoptosis. These fate decisions play a crucial role in maintaining homeostasis and critically depend on the interaction of the HSCs with their micro-environmental constituents. However, the physiological cues promoting these interactions in vivo have not been identified to a great extent. Intense research using various in vitro and in vivo models is going on in various laboratories to understand the mechanisms involved in these interactions, as understanding of these mechanistic would greatly help in improving clinical transplantations. However, though these elegant studies have identified the molecular interactions involved in the process, harnessing these interactions to the recipients' benefit would ultimately depend on manipulation of environmental cues initiating them in vivo: hence, these need to be identified at the earliest. HSCs reside in the bone marrow, which is a very complex tissue comprising of various types of stromal cells along with their secreted cytokines, extra-cellular matrix (ECM) molecules and extra-cellular vesicles (EVs). These components control the HSC fate decision through direct cell-cell interactions - mediated via various types of adhesion molecules -, cell-ECM interactions - mediated mostly via integrins -, or through soluble mediators like cytokines and EVs. This could be a very dynamic process involving multiple transient interactions acting concurrently or sequentially, and the adhesion molecules involved in various fate determining situations could be different. If the switch mechanisms governing these dynamic states in vivo are identified, they could be harnessed for the development of novel therapeutics. Here, in addition to reviewing the adhesion molecules involved in the regulation of HSCs, we also touch upon recent advances in our understanding of the physiological cues known to initiate specific adhesive interactions of HSCs with the marrow stromal cells or ECM molecules and EVs secreted by them.
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Affiliation(s)
- Rohan Kulkarni
- The Ohio State University Comprehensive Cancer Center, Columbus, OH, United States
| | - Vaijayanti Kale
- Symbiosis Centre for Stem Cell Research, Symbiosis International University, Pune, India
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12
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Bachmann M, Schäfer M, Mykuliak VV, Ripamonti M, Heiser L, Weißenbruch K, Krübel S, Franz CM, Hytönen VP, Wehrle-Haller B, Bastmeyer M. Induction of ligand promiscuity of αVβ3 integrin by mechanical force. J Cell Sci 2020; 133:jcs242404. [PMID: 32193334 DOI: 10.1242/jcs.242404] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/12/2020] [Indexed: 12/20/2022] Open
Abstract
αVβ3 integrin can bind to multiple extracellular matrix proteins, including vitronectin (Vn) and fibronectin (Fn), which are often presented to cells in culture as homogenous substrates. However, in tissues, cells experience highly complex and changing environments. To better understand integrin ligand selection in such complex environments, we employed binary-choice substrates of Fn and Vn to dissect αVβ3 integrin-mediated binding to different ligands on the subcellular scale. Super-resolution imaging revealed that αVβ3 integrin preferred binding to Vn under various conditions. In contrast, binding to Fn required higher mechanical load on αVβ3 integrin. Integrin mutations, structural analysis and chemical inhibition experiments indicated that the degree of hybrid domain swing-out is relevant for the selection between Fn and Vn; only a force-mediated, full hybrid domain swing-out facilitated αVβ3-Fn binding. Thus, force-dependent conformational changes in αVβ3 integrin increased the diversity of available ligands for binding and therefore enhanced the ligand promiscuity of this integrin.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Michael Bachmann
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Markus Schäfer
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen 76344, Germany
| | - Vasyl V Mykuliak
- Faculty of Medicine and Health Technology and BioMediTech, Tampere University, and Fimlab Laboratories, Tampere 33014, Finland
| | - Marta Ripamonti
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Lia Heiser
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Kai Weißenbruch
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Sarah Krübel
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
| | - Clemens M Franz
- DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- WPI Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Vesa P Hytönen
- Faculty of Medicine and Health Technology and BioMediTech, Tampere University, and Fimlab Laboratories, Tampere 33014, Finland
| | - Bernhard Wehrle-Haller
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Martin Bastmeyer
- Zoological Institute, Cell and Neurobiology, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen 76344, Germany
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13
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Changede R, Cai H, Wind SJ, Sheetz MP. Integrin nanoclusters can bridge thin matrix fibres to form cell-matrix adhesions. NATURE MATERIALS 2019; 18:1366-1375. [PMID: 31477904 PMCID: PMC7455205 DOI: 10.1038/s41563-019-0460-y] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/11/2019] [Indexed: 05/17/2023]
Abstract
Integrin-mediated cell-matrix adhesions are key to sensing the geometry and rigidity of extracellular environments and influence vital cellular processes. In vivo, the extracellular matrix is composed of fibrous arrays. To understand the fibre geometries that are required for adhesion formation, we patterned nanolines of various line widths and arrangements in single, crossing or paired arrays with the integrin-binding peptide Arg-Gly-Asp. Single thin lines (width ≤30 nm) did not support cell spreading or formation of focal adhesions, despite the presence of a high density of Arg-Gly-Asp, but wide lines (>40 nm) did. Using super-resolution microscopy, we observed stable, dense integrin clusters formed on parallel (within 110 nm) or crossing thin lines (mimicking a matrix mesh) similar to those on continuous substrates. These dense clusters bridged the line pairs by recruiting activated but unliganded integrins, as verified by integrin mutants unable to bind ligands that coclustered with ligand-bound integrins when present in an active extended conformation. Thus, in a fibrous extracellular matrix mesh, stable integrin nanoclusters bridge between thin (≤30 nm) matrix fibres and bring about downstream consequences of cell motility and growth.
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Affiliation(s)
- Rishita Changede
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore.
| | - Haogang Cai
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
- Center for Nanoscale Materials, Nanoscience and Technology Division, Argonne National laboratory, Lemont, IL, USA
| | - Shalom J Wind
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - Michael P Sheetz
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore.
- Molecular Mechanomedicine Program, Biochemistry and Molecular Biology Department, University of Texas Medical Branch, Galveston, TX, USA.
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14
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Abstract
Integrins are heterodimeric cell surface receptors ensuring the mechanical connection between cells and the extracellular matrix. In addition to the anchorage of cells to the extracellular matrix, these receptors have critical functions in intracellular signaling, but are also taking center stage in many physiological and pathological conditions. In this review, we provide some historical, structural, and physiological notes so that the diverse functions of these receptors can be appreciated and put into the context of the emerging field of mechanobiology. We propose that the exciting journey of the exploration of these receptors will continue for at least another new generation of researchers.
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Affiliation(s)
- Michael Bachmann
- Department of Cell Physiology and Metabolism, University of Geneva, Centre Médical Universitaire , Geneva , Switzerland ; and Faculty of Medicine and Health Technology, Tampere University, and Fimlab Laboratories , Tampere , Finland
| | - Sampo Kukkurainen
- Department of Cell Physiology and Metabolism, University of Geneva, Centre Médical Universitaire , Geneva , Switzerland ; and Faculty of Medicine and Health Technology, Tampere University, and Fimlab Laboratories , Tampere , Finland
| | - Vesa P Hytönen
- Department of Cell Physiology and Metabolism, University of Geneva, Centre Médical Universitaire , Geneva , Switzerland ; and Faculty of Medicine and Health Technology, Tampere University, and Fimlab Laboratories , Tampere , Finland
| | - Bernhard Wehrle-Haller
- Department of Cell Physiology and Metabolism, University of Geneva, Centre Médical Universitaire , Geneva , Switzerland ; and Faculty of Medicine and Health Technology, Tampere University, and Fimlab Laboratories , Tampere , Finland
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15
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Autonomous conformational regulation of β 3 integrin and the conformation-dependent property of HPA-1a alloantibodies. Proc Natl Acad Sci U S A 2018; 115:E9105-E9114. [PMID: 30209215 DOI: 10.1073/pnas.1806205115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Integrin α/β heterodimer adopts a compact bent conformation in the resting state, and upon activation undergoes a large-scale conformational rearrangement. During the inside-out activation, signals impinging on the cytoplasmic tail of β subunit induce the α/β separation at the transmembrane and cytoplasmic domains, leading to the extended conformation of the ectodomain with the separated leg and the opening headpiece that is required for the high-affinity ligand binding. It remains enigmatic which integrin subunit drives the bent-to-extended conformational rearrangement in the inside-out activation. The β3 integrins, including αIIbβ3 and αVβ3, are the prototypes for understanding integrin structural regulation. The Leu33Pro polymorphism located at the β3 PSI domain defines the human platelet-specific alloantigen (HPA) 1a/b, which provokes the alloimmune response leading to clinically important bleeding disorders. Some, but not all, anti-HPA-1a alloantibodies can distinguish the αIIbβ3 from αVβ3 and affect their functions with unknown mechanisms. Here we designed a single-chain β3 subunit that mimics a separation of α/β heterodimer on inside-out activation. Our crystallographic and functional studies show that the single-chain β3 integrin folds into a bent conformation in solution but spontaneously extends on the cell surface. This demonstrates that the β3 subunit autonomously drives the membrane-dependent conformational rearrangement during integrin activation. Using the single-chain β3 integrin, we identified the conformation-dependent property of anti-HPA-1a alloantibodies, which enables them to differently recognize the β3 in the bent state vs. the extended state and in the complex with αIIb vs. αV This study provides deeper understandings of integrin conformational activation on the cell surface.
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16
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Passam F, Chiu J, Ju L, Pijning A, Jahan Z, Mor-Cohen R, Yeheskel A, Kolšek K, Thärichen L, Aponte-Santamaría C, Gräter F, Hogg PJ. Mechano-redox control of integrin de-adhesion. eLife 2018; 7:e34843. [PMID: 29932420 PMCID: PMC6054529 DOI: 10.7554/elife.34843] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 06/21/2018] [Indexed: 12/17/2022] Open
Abstract
How proteins harness mechanical force to control function is a significant biological question. Here we describe a human cell surface receptor that couples ligand binding and force to trigger a chemical event which controls the adhesive properties of the receptor. Our studies of the secreted platelet oxidoreductase, ERp5, have revealed that it mediates release of fibrinogen from activated platelet αIIbβ3 integrin. Protein chemical studies show that ligand binding to extended αIIbβ3 integrin renders the βI-domain Cys177-Cys184 disulfide bond cleavable by ERp5. Fluid shear and force spectroscopy assays indicate that disulfide cleavage is enhanced by mechanical force. Cell adhesion assays and molecular dynamics simulations demonstrate that cleavage of the disulfide induces long-range allosteric effects within the βI-domain, mainly affecting the metal-binding sites, that results in release of fibrinogen. This coupling of ligand binding, force and redox events to control cell adhesion may be employed to regulate other protein-protein interactions.
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Affiliation(s)
| | - Joyce Chiu
- The Centenary InstituteNewtownAustralia
- National Health and Medical Research Council Clinical Trials CentreUniversity of SydneySydneyAustralia
| | - Lining Ju
- Heart Research Institute and Charles Perkins CentreUniversity of SydneySydneyAustralia
| | | | | | - Ronit Mor-Cohen
- The Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer and Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Adva Yeheskel
- The Bioinformatics Unit, George S. Wise Faculty of Life ScienceTel Aviv UniversityTel AvivIsrael
| | - Katra Kolšek
- Heidelberg Institute of Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Lena Thärichen
- Heidelberg Institute of Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Camilo Aponte-Santamaría
- Heidelberg Institute of Theoretical StudiesHeidelbergGermany
- Max Planck Tandem Group in Computational BiophysicsUniversity of Los AndesBogotáColombia
| | - Frauke Gräter
- Heidelberg Institute of Theoretical StudiesHeidelbergGermany
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityHeidelbergGermany
| | - Philip J Hogg
- The Centenary InstituteNewtownAustralia
- National Health and Medical Research Council Clinical Trials CentreUniversity of SydneySydneyAustralia
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17
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Hu P, Luo B. The interface between the EGF1 and EGF2 domains is critical in integrin affinity regulation. J Cell Biochem 2018; 119:7264-7273. [DOI: 10.1002/jcb.26921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 04/04/2018] [Indexed: 02/02/2023]
Affiliation(s)
- Ping Hu
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
- Department of Biomedical EngineeringUniversity of VirginiaCharlottesvilleVirginia
| | - Bing‐Hao Luo
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
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18
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Pagani G, Gohlke H. On the contributing role of the transmembrane domain for subunit-specific sensitivity of integrin activation. Sci Rep 2018; 8:5733. [PMID: 29636500 PMCID: PMC5893634 DOI: 10.1038/s41598-018-23778-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/20/2018] [Indexed: 12/20/2022] Open
Abstract
Integrins are α/β heterodimeric transmembrane adhesion receptors. Evidence exists that their transmembrane domain (TMD) separates upon activation. Subunit-specific differences in activation sensitivity of integrins were reported. However, whether sequence variations in the TMD lead to differential TMD association has remained elusive. Here, we show by molecular dynamics simulations and association free energy calculations on TMDs of integrin αIIbβ3, αvβ3, and α5β1 that αIIbβ3 TMD is most stably associated; this difference is related to interaction differences across the TMDs. The order of TMD association stability is paralleled by the basal activity of these integrins, which suggests that TMD differences can have a decisive effect on integrin conformational free energies. We also identified a specific order of clasp disintegration upon TMD dissociation, which suggests that the closed state of integrins may comprise several microstates. Our results provide unprecedented insights into a possibly contributing role of TMD towards subunit-specific sensitivity of integrin activation.
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Affiliation(s)
- Giulia Pagani
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Holger Gohlke
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC) & Institute for Complex Systems - Structural Biochemistry (ICS 6), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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19
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The importance of N-glycosylation on β 3 integrin ligand binding and conformational regulation. Sci Rep 2017; 7:4656. [PMID: 28680094 PMCID: PMC5498496 DOI: 10.1038/s41598-017-04844-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/19/2017] [Indexed: 11/25/2022] Open
Abstract
N-glycosylations can regulate the adhesive function of integrins. Great variations in both the number and distribution of N-glycosylation sites are found in the 18 α and 8 β integrin subunits. Crystal structures of αIIbβ3 and αVβ3 have resolved the precise structural location of each N-glycan site, but the structural consequences of individual N-glycan site on integrin activation remain unclear. By site-directed mutagenesis and structure-guided analyses, we dissected the function of individual N-glycan sites in β3 integrin activation. We found that the N-glycan site, β3-N320 at the headpiece and leg domain interface positively regulates αIIbβ3 but not αVβ3 activation. The β3-N559 N-glycan at the β3-I-EGF3 and αIIb-calf-1 domain interface, and the β3-N654 N-glycan at the β3-β-tail and αIIb-calf-2 domain interface positively regulate the activation of both αIIbβ3 and αVβ3 integrins. In contrast, removal of the β3-N371 N-glycan near the β3 hybrid and I-EGF3 interface, or the β3-N452 N-glycan at the I-EGF1 domain rendered β3 integrin more active than the wild type. We identified one unique N-glycan at the βI domain of β1 subunit that negatively regulates α5β1 activation. Our study suggests that the bulky N-glycans influence the large-scale conformational rearrangement by potentially stabilizing or destabilizing the domain interfaces of integrin.
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20
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Wang L, Pan D, Yan Q, Song Y. Activation mechanisms of αVβ3 integrin by binding to fibronectin: A computational study. Protein Sci 2017; 26:1124-1137. [PMID: 28340512 PMCID: PMC5441423 DOI: 10.1002/pro.3163] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/13/2017] [Accepted: 03/19/2017] [Indexed: 01/29/2023]
Abstract
Integrin αVβ3 plays an important role in regulating cellular activities and in human diseases. Although the structure of αVβ3 has been studied by crystallography and electron microscopy, the detailed activation mechanism of integrin αVβ3 induced by fibronectin remains unclear. In this study, we investigated the conformational and dynamical motion changes of Mn2+ -bound integrin αVβ3 by binding to fibronectin with molecular dynamics simulations. Results showed that fibronectin binding to integrin αVβ3 caused the changes of the conformational flexibility of αVβ3 domains, the essential mode of motion for the domains of αV subunit and β3 subunit and the degrees of correlated motion of residues between the domains of αV subunit and β3 subunit of integrin αVβ3. The angle of Propeller domain with respect to the Calf-2 domain of αV subunit and the angle of Hybrid domain with respect to βA domain of β3 subunit significantly increased when integrin αVβ3 was bound to fibronectin. These changes could result in the conformational change tendency of αVβ3 from a bend conformation to an extended conformation and lead to the open swing of Hybrid domain relative to βA domain of β3 subunit, which have demonstrated their importance for αVβ3 activation. Fibronectin binding to integrin αVβ3 significantly decreased the relative position of α1 helix to βA domain and that to metal ion-dependent adhesion site, stabilized Mn2+ ions binding in integrin αVβ3 and changed fibronectin conformation, which are important for αVβ3 activation. Results from this study provide important molecular insight into the "outside-in" activation mechanism of integrin αVβ3 by binding to fibronectin.
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Affiliation(s)
- Lingyun Wang
- Department of Biomedical EngineeringThe University of Alabama at BirminghamBirminghamAlabama35294
| | - Di Pan
- Department of Biomedical EngineeringThe University of Alabama at BirminghamBirminghamAlabama35294
| | - Qi Yan
- Department of Biomedical EngineeringThe University of Alabama at BirminghamBirminghamAlabama35294
| | - Yuhua Song
- Department of Biomedical EngineeringThe University of Alabama at BirminghamBirminghamAlabama35294
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21
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Hang Q, Isaji T, Hou S, Zhou Y, Fukuda T, Gu J. N-Glycosylation of integrin α5 acts as a switch for EGFR-mediated complex formation of integrin α5β1 to α6β4. Sci Rep 2016; 6:33507. [PMID: 27641064 PMCID: PMC5027594 DOI: 10.1038/srep33507] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/23/2016] [Indexed: 01/17/2023] Open
Abstract
N-Glycosylation of integrin α5β1 is involved in multiple cell behaviors. We previously reported that the N-glycosylations of the calf domain on integrin α5 (S3–5,10–14) are essential for its inhibitory effect on EGFR signaling in regulating cell proliferation. However, the importance of the individual N-glycosylation and the underlying mechanisms of inhibition remain unclear. Here, we characterize the S3–5,10–14 mutants in detail and found that the N-glycosylation of site-11 (Asn712) is key for cell growth. The restoration of site-11, unlike the other individual sites, significantly suppressed cell growth and EGFR signaling in a manner that was similar to that of wild-type (WT). Mechanistically, this N-glycosylation inhibited the response abilities upon EGF stimulation and EGFR dimerization. Interestingly, we found this N-glycosylation controlled the EGFR complex formation with integrin α5β1 or α6β4; i.e., the loss of site-11 switched EGFR-α5β1 to EGFR-α6β4, which is well known to promote cellular signaling for cell growth. Moreover, the site-11 N-glycan exhibited a more branching structure compared with other sites, which may be required for EGFR-α5β1 formation. Taken together, these data clearly demonstrate that the site-11 N-glycosylation on α5 is most important for its inhibitory effect on EGFR signaling, which may provide a novel regulatory mechanism for crosstalks between integrins and EGFR.
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Affiliation(s)
- Qinglei Hang
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
| | - Tomoya Isaji
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
| | - Sicong Hou
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
| | - Ying Zhou
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
| | - Tomohiko Fukuda
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
| | - Jianguo Gu
- Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi, 981-8558, Japan
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22
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Hou S, Hang Q, Isaji T, Lu J, Fukuda T, Gu1 J. Importance of membrane‐proximal
N
‐glycosylation on integrin α1 in its activation and complex formation. FASEB J 2016; 30:4120-4131. [DOI: 10.1096/fj.201600665r] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 08/15/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Sicong Hou
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
| | - Qinglei Hang
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
| | - Tomoya Isaji
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
| | - Jishun Lu
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
| | - Tomohiko Fukuda
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
| | - Jianguo Gu1
- Division of Regulatory GlycobiologyInstitute of Molecular Biomembrane and Glycobiology Tohoku Medical and Pharmaceutical University Miyagi Japan
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23
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Navarro AP, Collins MA, Folker ES. The nucleus is a conserved mechanosensation and mechanoresponse organelle. Cytoskeleton (Hoboken) 2016; 73:59-67. [PMID: 26849407 DOI: 10.1002/cm.21277] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/22/2016] [Accepted: 01/22/2016] [Indexed: 11/05/2022]
Abstract
Cells in vivo exist in a dynamic environment where they experience variable mechanical influences. The precise mechanical environment influences cell-cell interactions, cell-extracellular matrix interactions, and in-turn, cell morphology and cell function. Therefore, the ability of each cell to constantly and rapidly alter their behavior in response to variations in their mechanical environment is essential for cell viability, development, and function. Mechanotransduction, the process by which mechanical force is translated into a biochemical signal to activate downstream cellular responses, is thus crucial to cell function during development and homeostasis. Although much research has focused on how protein complexes at the cell cortex respond to mechanical stress to initiate mechanotransduction, the nucleus has emerged as crucial to the ability of the cell to perceive and respond to changes in its mechanical environment. This additional method for mechanosensing allows for direct transmission of force through the cytoskeleton to the nucleus, which can increase the speed at which a cell changes its transcriptional profile. This review discusses recent work demonstrating the importance of the nucleus in mediating the cellular response to internal and external force, establishing the nucleus as an important mechanosensing organelle.
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Affiliation(s)
- Alexandra P Navarro
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02142
| | - Mary Ann Collins
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, 02467
| | - Eric S Folker
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, 02467
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24
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Lin FY, Zhu J, Eng ET, Hudson NE, Springer TA. β-Subunit Binding Is Sufficient for Ligands to Open the Integrin αIIbβ3 Headpiece. J Biol Chem 2015; 291:4537-46. [PMID: 26631735 PMCID: PMC4813479 DOI: 10.1074/jbc.m115.705624] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Indexed: 12/15/2022] Open
Abstract
The platelet integrin αIIbβ3 binds to a KQAGDV motif at the fibrinogen γ-chain C terminus and to RGD motifs present in loops in many extracellular matrix proteins. These ligands bind in a groove between the integrin α and β-subunits; the basic Lys or Arg side chain hydrogen bonds to the αIIb-subunit, and the acidic Asp side chain coordinates to a metal ion held by the β3-subunit. Ligand binding induces headpiece opening, with conformational change in the β-subunit. During this opening, RGD slides in the ligand-binding pocket toward αIIb, with movement of the βI-domain β1-α1 loop toward αIIb, enabling formation of direct, charged hydrogen bonds between the Arg side chain and αIIb. Here we test whether ligand interactions with β3 suffice for stable ligand binding and headpiece opening. We find that the AGDV tetrapeptide from KQAGDV binds to the αIIbβ3 headpiece with affinity comparable with the RGDSP peptide from fibronectin. AGDV induced complete headpiece opening in solution as shown by increase in hydrodynamic radius. Soaking of AGDV into closed αIIbβ3 headpiece crystals induced intermediate states similarly to RGDSP. AGDV has very little contact with the α-subunit. Furthermore, as measured by epitope exposure, AGDV, like the fibrinogen γ C-terminal peptide and RGD, caused integrin extension on the cell surface. Thus, pushing by the β3-subunit on Asp is sufficient for headpiece opening and ligand sliding, and no pulling by the αIIb subunit on Arg is required.
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Affiliation(s)
- Fu-Yang Lin
- From the Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Jianghai Zhu
- From the Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Edward T Eng
- From the Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Nathan E Hudson
- From the Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Timothy A Springer
- From the Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
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25
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Minagawa S, Lou J, Seed RI, Cormier A, Wu S, Cheng Y, Murray L, Tsui P, Connor J, Herbst R, Govaerts C, Barker T, Cambier S, Yanagisawa H, Goodsell A, Hashimoto M, Brand OJ, Cheng R, Ma R, McKnelly KJ, Wen W, Hill A, Jablons D, Wolters P, Kitamura H, Araya J, Barczak AJ, Erle DJ, Reichardt LF, Marks JD, Baron JL, Nishimura SL. Selective targeting of TGF-β activation to treat fibroinflammatory airway disease. Sci Transl Med 2015; 6:241ra79. [PMID: 24944194 DOI: 10.1126/scitranslmed.3008074] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Airway remodeling, caused by inflammation and fibrosis, is a major component of chronic obstructive pulmonary disease (COPD) and currently has no effective treatment. Transforming growth factor-β (TGF-β) has been widely implicated in the pathogenesis of airway remodeling in COPD. TGF-β is expressed in a latent form that requires activation. The integrin αvβ8 (encoded by the itgb8 gene) is a receptor for latent TGF-β and is essential for its activation. Expression of integrin αvβ8 is increased in airway fibroblasts in COPD and thus is an attractive therapeutic target for the treatment of airway remodeling in COPD. We demonstrate that an engineered optimized antibody to human αvβ8 (B5) inhibited TGF-β activation in transgenic mice expressing only human and not mouse ITGB8. The B5 engineered antibody blocked fibroinflammatory responses induced by tobacco smoke, cytokines, and allergens by inhibiting TGF-β activation. To clarify the mechanism of action of B5, we used hydrodynamic, mutational, and electron microscopic methods to demonstrate that αvβ8 predominantly adopts a constitutively active, extended-closed headpiece conformation. Epitope mapping and functional characterization of B5 revealed an allosteric mechanism of action due to locking-in of a low-affinity αvβ8 conformation. Collectively, these data demonstrate a new model for integrin function and present a strategy to selectively target the TGF-β pathway to treat fibroinflammatory airway diseases.
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Affiliation(s)
- Shunsuke Minagawa
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Jianlong Lou
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Robert I Seed
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Anthony Cormier
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Shenping Wu
- The Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Yifan Cheng
- The Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Lynne Murray
- Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Gaithersburg, MD 20878, USA. Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Cambridge CB21 6GH, UK
| | - Ping Tsui
- Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Gaithersburg, MD 20878, USA
| | - Jane Connor
- Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Gaithersburg, MD 20878, USA
| | - Ronald Herbst
- Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Gaithersburg, MD 20878, USA
| | - Cedric Govaerts
- Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Cambridge CB21 6GH, UK
| | - Tyren Barker
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Stephanie Cambier
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Haruhiko Yanagisawa
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Amanda Goodsell
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Mitsuo Hashimoto
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Oliver J Brand
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Ran Cheng
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Royce Ma
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Kate J McKnelly
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Weihua Wen
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Arthur Hill
- Department of Surgery, University of California, San Francisco, San Francisco, CA 94110, USA
| | - David Jablons
- Department of Surgery, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Paul Wolters
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Hideya Kitamura
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Jun Araya
- Department of Pulmonary Medicine, Jikei University, Tokyo 105 8461, Japan
| | - Andrea J Barczak
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94110, USA
| | - David J Erle
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Louis F Reichardt
- Genetics, Development, and Behavioral Sciences, University of California, San Francisco, San Francisco, CA 94110, USA
| | - James D Marks
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Jody L Baron
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94110, USA
| | - Stephen L Nishimura
- Department of Pathology, University of California, San Francisco, San Francisco, CA 94110, USA.
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26
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Kakegawa W, Mitakidis N, Miura E, Abe M, Matsuda K, Takeo Y, Kohda K, Motohashi J, Takahashi A, Nagao S, Muramatsu SI, Watanabe M, Sakimura K, Aricescu A, Yuzaki M. Anterograde C1ql1 Signaling Is Required in Order to Determine and Maintain a Single-Winner Climbing Fiber in the Mouse Cerebellum. Neuron 2015; 85:316-29. [DOI: 10.1016/j.neuron.2014.12.020] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2014] [Indexed: 10/24/2022]
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27
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Cheng M, Li J, Negri A, Coller BS. Swing-out of the β3 hybrid domain is required for αIIbβ3 priming and normal cytoskeletal reorganization, but not adhesion to immobilized fibrinogen. PLoS One 2013; 8:e81609. [PMID: 24349096 PMCID: PMC3857192 DOI: 10.1371/journal.pone.0081609] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 10/15/2013] [Indexed: 12/24/2022] Open
Abstract
Structural and functional analyses of integrin αIIbβ3 has implicated swing-out motion of the β3 hybrid domain in αIIbβ3 activation and ligand binding. Using data from targeted molecular dynamics (TMD) simulations, we engineered two disulfide-bonded mutant receptors designed to limit swing-out (XS-O). XS-O mutants cannot bind the high Mr ligand fibrinogen in the presence of an activating mAb or after introducing mutations into the αIIb subunit designed to simulate inside-out signaling. They also have reduced capacity to be “primed” to bind fibrinogen by pretreatment with eptifibatide. They can, however, bind the small RGD venom protein kistrin. Despite their inability to bind soluble fibrinogen, the XS-O mutants can support adhesion to immobilized fibrinogen, although such adhesion does not initiate outside-in signaling leading to normal cytoskeletal reorganization. Collectively, our data further define the biologic role of β3 hybrid domain swing-out in both soluble and immobilized high Mr ligand binding, as well as in priming and outside-in signaling. We also infer that swing-out is likely to be a downstream effect of receptor extension.
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Affiliation(s)
- Ming Cheng
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, New York, United States of America
| | - Jihong Li
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, New York, United States of America
| | - Ana Negri
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Barry S. Coller
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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28
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Jung JY, Oh JH, Lee DH, Lee S, Chung JH. Blood type B antigen modulates cell migration through regulating cdc42 expression and activity in HaCaT cells. J Cell Physiol 2013; 228:2243-51. [PMID: 23625752 DOI: 10.1002/jcp.24393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 04/18/2013] [Indexed: 11/05/2022]
Abstract
ABO blood group is determined by carbohydrate antigens, called ABH antigens. It has been known that the change of carbohydrate antigen expression, including ABH antigens, has correlation with the tumor metastasis and survival; however, the exact mechanism remains to be elucidated. ABH antigens are expressed not only in blood cells but also in several tissues. In epidermis, ABH antigen is expressed in the uppermost spinous and granular layer. We investigated the role of ABH antigens on the cell migration of HaCaT keratinocytes, which express B antigen. Knock-down of B antigen expression by small interference RNA of FUT1 inhibited HaCaT cell migration. At that time, we found that lamellipodia and actin fiber were also reduced by knock-down of B antigen expression. The transcription of cdc42, a kind of Rho GTPase which plays a key role in actin polymerization, was reduced by down-regulated B antigen expression. Furthermore, the reduced B antigen expression also inhibited the interaction of cdc42 and N-WASP. Collectively, our data provide a clue how ABH antigens regulate the cell migration mechanism.
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Affiliation(s)
- Ji-Yong Jung
- Department of Dermatology, Seoul National University College of Medicine, Medical Research Center, Seoul National University, Medical Research Center, Seoul National University, Seoul, Korea
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29
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Raborn J, Fu T, Wu X, Xiu Z, Li G, Luo BH. Variation in one residue associated with the metal ion-dependent adhesion site regulates αIIbβ3 integrin ligand binding affinity. PLoS One 2013; 8:e76793. [PMID: 24116162 PMCID: PMC3792891 DOI: 10.1371/journal.pone.0076793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/29/2013] [Indexed: 01/06/2023] Open
Abstract
The Asp of the RGD motif of the ligand coordinates with the β I domain metal ion dependent adhesion site (MIDAS) divalent cation, emphasizing the importance of the MIDAS in ligand binding. There appears to be two distinct groups of integrins that differ in their ligand binding affinity and adhesion ability. These differences may be due to a specific residue associated with the MIDAS, particularly the β3 residue Ala252 and corresponding Ala in the β1 integrin compared to the analogous Asp residue in the β2 and β7 integrins. Interestingly, mutations in the adjacent to MIDAS (ADMIDAS) of integrins α4β7 and αLβ2 increased the binding and adhesion abilities compared to the wild-type, while the same mutations in the α2β1, α5β1, αVβ3, and αIIbβ3 integrins demonstrated decreased ligand binding and adhesion. We introduced a mutation in the αIIbβ3 to convert this MIDAS associated Ala252 to Asp. By combination of this mutant with mutations of one or two ADMIDAS residues, we studied the effects of this residue on ligand binding and adhesion. Then, we performed molecular dynamics simulations on the wild-type and mutant αIIbβ3 integrin β I domains, and investigated the dynamics of metal ion binding sites in different integrin-RGD complexes. We found that the tendency of calculated binding free energies was in excellent agreement with the experimental results, suggesting that the variation in this MIDAS associated residue accounts for the differences in ligand binding and adhesion among different integrins, and it accounts for the conflicting results of ADMIDAS mutations within different integrins. This study sheds more light on the role of the MIDAS associated residue pertaining to ligand binding and adhesion and suggests that this residue may play a pivotal role in integrin-mediated cell rolling and firm adhesion.
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Affiliation(s)
- Joel Raborn
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
- University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, United States of America
| | - Ting Fu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, PR China
- Department of Bioscience and Biotechnology, Dalian University of Technology, Dalian, PR China
- Graduate University of the Chinese Academy of Sciences, Beijing, P. R. China
| | - Xue Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, PR China
- Department of Bioscience and Biotechnology, Dalian University of Technology, Dalian, PR China
| | - Zhilong Xiu
- Department of Bioscience and Biotechnology, Dalian University of Technology, Dalian, PR China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, PR China
- * E-mail: (GL); (BL)
| | - Bing-Hao Luo
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail: (GL); (BL)
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Abstract
Crystals soaked with RGD peptides reveal six intermediate conformational states between the closed and higher affinity, fully open state of the integrin αIIbβ3 headpiece. Carefully soaking crystals with Arg-Gly-Asp (RGD) peptides, we captured eight distinct RGD-bound conformations of the αIIbβ3 integrin headpiece. Starting from the closed βI domain conformation, we saw six intermediate βI conformations and finally the fully open βI with the hybrid domain swung out in the crystal lattice. The β1-α1 backbone that hydrogen bonds to the Asp side chain of RGD was the first element to move followed by adjacent to metal ion-dependent adhesion site Ca2+, α1 helix, α1’ helix, β6-α7 loop, α7 helix, and hybrid domain. We define in atomic detail how conformational change was transmitted over long distances in integrins, 40 Å from the ligand binding site to the opposite end of the βI domain and 80 Å to the far end of the hybrid domain. During these movements, RGD slid in its binding groove toward αIIb, and its Arg side chain became ordered. RGD concentration requirements in soaking suggested a >200-fold higher affinity after opening. The thermodynamic cycle shows how higher affinity pays the energetic cost of opening.
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Affiliation(s)
- Jieqing Zhu
- Department of Biological Chemistry and Molecular Pharmacology, Program in Cellular and Molecular Medicine, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA
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31
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Nurden AT, Pillois X, Wilcox DA. Glanzmann thrombasthenia: state of the art and future directions. Semin Thromb Hemost 2013; 39:642-55. [PMID: 23929305 DOI: 10.1055/s-0033-1353393] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Glanzmann thrombasthenia (GT) is the principal inherited disease of platelets and the most commonly encountered disorder of an integrin. GT is characterized by spontaneous mucocutaneous bleeding and an exaggerated response to trauma caused by platelets that fail to aggregate when stimulated by physiologic agonists. GT is caused by quantitative or qualitative deficiencies of αIIbβ3, an integrin coded by the ITGA2B and ITGB3 genes and which by binding fibrinogen and other adhesive proteins joins platelets together in the aggregate. Widespread genotyping has revealed that mutations spread across both genes, yet the reason for the extensive variation in both the severity and intensity of bleeding between affected individuals remains poorly understood. Furthermore, although genetic defects of ITGB3 affect other tissues with β3 present as αvβ3 (the vitronectin receptor), the bleeding phenotype continues to dominate. Here, we look in detail at mutations that affect (i) the β-propeller region of the αIIb head domain and (ii) the membrane proximal disulfide-rich epidermal growth factor (EGF) domains of β3 and which often result in spontaneous integrin activation. We also examine deep vein thrombosis as an unexpected complication of GT and look at curative procedures for the diseases, including allogeneic stem cell transfer and the potential for gene therapy.
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Affiliation(s)
- Alan T Nurden
- Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France.
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32
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Aricescu AR, Owens RJ. Expression of recombinant glycoproteins in mammalian cells: towards an integrative approach to structural biology. Curr Opin Struct Biol 2013; 23:345-56. [PMID: 23623336 DOI: 10.1016/j.sbi.2013.04.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 03/30/2013] [Accepted: 04/02/2013] [Indexed: 01/26/2023]
Abstract
Mammalian cells are rapidly becoming the system of choice for the production of recombinant glycoproteins for structural biology applications. Their use has enabled the structural investigation of a whole new set of targets including large, multi-domain and highly glycosylated eukaryotic cell surface receptors and their supra-molecular assemblies. We summarize the technical advances that have been made in mammalian expression technology and highlight some of the structural insights that have been obtained using these methods. Looking forward, it is clear that mammalian cell expression will provide exciting and unique opportunities for an integrative approach to the structural study of proteins, especially of human origin and medically relevant, by bridging the gap between the purified state and the cellular context.
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Affiliation(s)
- A Radu Aricescu
- Division of Structural Biology, University of Oxford, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
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Yuki K, Bu W, Shimaoka M, Eckenhoff R. Volatile anesthetics, not intravenous anesthetic propofol bind to and attenuate the activation of platelet receptor integrin αIIbβ3. PLoS One 2013; 8:e60415. [PMID: 23573252 PMCID: PMC3616120 DOI: 10.1371/journal.pone.0060415] [Citation(s) in RCA: 26] [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: 10/31/2012] [Accepted: 02/27/2013] [Indexed: 12/03/2022] Open
Abstract
Background In clinical reports, the usage of isoflurane and sevoflurane was associated with more surgical field bleeding in endoscopic sinus surgeries as compared to propofol. The activation of platelet receptor αIIbβ3 is a crucial event for platelet aggregation and clot stability. Here we studied the effect of isoflurane, sevoflurane, and propofol on the activation of αIIbβ3. Methods The effect of anesthetics on the activation of αIIbβ3 was probed using the activation sensitive antibody PAC-1 in both cell-based (platelets and αIIbβ3 transfectants) and cell-free assays. The binding sites of isoflurane on αIIbβ3 were explored using photoactivatable isoflurane (azi-isoflurane). The functional implication of revealed isoflurane binding sites were studied using alanine-scanning mutagenesis. Results Isoflurane and sevoflurane diminished the binding of PAC-1 to wild-type αIIbβ3 transfectants, but not to the high-affinity mutant, β3-N305T. Both anesthetics also impaired PAC-1 binding in a cell-free assay. In contrast, propofol did not affect the activation of αIIbβ3. Residues adducted by azi-isoflurane were near the calcium binding site (an important regulatory site termed SyMBS) just outside of the ligand binding site. The mutagenesis experiments demonstrated that these adducted residues were important in regulating integrin activation. Conclusions Isoflurane and sevoflurane, but not propofol, impaired the activation of αIIbβ3. Azi-isoflurane binds to the regulatory site of integrin αIIbβ3, thereby suggesting that isoflurane blocks ligand binding of αIIbβ3 in not a competitive, but an allosteric manner.
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Affiliation(s)
- Koichi Yuki
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, United States of America.
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34
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Zapotoczna M, Jevnikar Z, Miajlovic H, Kos J, Foster TJ. Iron-regulated surface determinant B (IsdB) promotes Staphylococcus aureus adherence to and internalization by non-phagocytic human cells. Cell Microbiol 2013; 15:1026-41. [PMID: 23279065 DOI: 10.1111/cmi.12097] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 11/28/2012] [Accepted: 12/13/2012] [Indexed: 01/22/2023]
Abstract
Staphylococcus aureus is a human pathogen that causes invasive and recurring infections. The ability to internalize into and persist within host cells is thought to contribute to infection. Here we report a novel role for the well-characterized iron-regulated surface determinant B (IsdB) protein which we have shown can promote adhesion of 293T, HeLa cells and platelets to immobilized bacteria independently of its ability to bind haemoglobin. IsdB bound to the active form of the platelet integrin αIIb β3 , both on platelets and when the integrin was expressed ectopically in CHO cells. IsdB also promoted bacterial invasion into human cells. This was clearly demonstrated with bacteria lacking fibronectin-binding proteins (FnBPs), which are known to promote invasion in the presence of fibronectin. However, IsdB also contributed significantly to invasion by cells expressing FnBPs in the presence of serum. Thus IsdB appears to be able to interact with the broader family of integrins that bind ligands with the RGD motif and to act as a back up mechanism to promote interactions with mammalian cells.
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Affiliation(s)
- Marta Zapotoczna
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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35
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Zhang C, Liu J, Jiang X, Haydar N, Zhang C, Shan H, Zhu J. Modulation of integrin activation and signaling by α1/α1′-helix unbending at the junction. J Cell Sci 2013; 126:5735-47. [DOI: 10.1242/jcs.137828] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
How conformational signals initiated from one end of the integrin are transmitted to the other end remains elusive. At the ligand-binding βI domain, the α1/α1′-helix changes from a bent to a straightened α-helical conformation upon integrin headpiece opening. We demonstrated that a conserved glycine at the α1/α1′ junction is critical for maintaining the bent conformation of the α1/α1′-helix in the resting state. Mutations that facilitate α1/α1′-helix unbending rendered integrin constitutively active. However, mutations that block the α1/α1′-helix unbending abolished soluble ligand binding upon either outside or inside stimuli. Such mutations also blocked ligand-induced integrin extension from outside the cell, but had no effect on talin-induced integrin extension from inside the cell. In addition, integrin mediated cell spreading, F-actin stress fiber and focal adhesion formation, and focal adhesion kinase activation were also defective in these mutant integrins, although the cells still adhered to immobilized ligands at a reduced level. Our data establish the structural role of the α1/α1′ junction that allows relaxation of the α1/α1′-helix in the resting state and transmission of bidirectional conformational signals by helix unbending upon integrin activation.
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36
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Dong X, Mi LZ, Zhu J, Wang W, Hu P, Luo BH, Springer TA. α(V)β(3) integrin crystal structures and their functional implications. Biochemistry 2012; 51:8814-28. [PMID: 23106217 PMCID: PMC3495331 DOI: 10.1021/bi300734n] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many questions about the significance of structural features of integrin α(V)β(3) with respect to its mechanism of activation remain. We have determined and re-refined crystal structures of the α(V)β(3) ectodomain linked to C-terminal coiled coils (α(V)β(3)-AB) and four transmembrane (TM) residues in each subunit (α(V)β(3)-1TM), respectively. The α(V) and β(3) subunits with four and eight extracellular domains, respectively, are bent at knees between the integrin headpiece and lower legs, and the headpiece has the closed, low-affinity conformation. The structures differ in the occupancy of three metal-binding sites in the βI domain. Occupancy appears to be related to the pH of crystallization, rather than to the physiologic regulation of ligand binding at the central, metal ion-dependent adhesion site. No electron density was observed for TM residues and much of the α(V) linker. α(V)β(3)-AB and α(V)β(3)-1TM demonstrate flexibility in the linker between their extracellular and TM domains, rather than the previously proposed rigid linkage. A previously postulated interface between the α(V) and β(3) subunits at their knees was also not supported, because it lacks high-quality density, required rebuilding in α(V)β(3)-1TM, and differed markedly between α(V)β(3)-1TM and α(V)β(3)-AB. Together with the variation in domain-domain orientation within their bent ectodomains between α(V)β(3)-AB and α(V)β(3)-1TM, these findings are compatible with the requirement for large structural changes, such as extension at the knees and headpiece opening, in conveying activation signals between the extracellular ligand-binding site and the cytoplasm.
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Affiliation(s)
- Xianchi Dong
- Immune Disease Institute, Children's Hospital Boston and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
| | - Li-Zhi Mi
- Immune Disease Institute, Children's Hospital Boston and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
| | - Jianghai Zhu
- Immune Disease Institute, Children's Hospital Boston and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
| | - Wei Wang
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803
| | - Ping Hu
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803
| | - Bing-Hao Luo
- Immune Disease Institute, Children's Hospital Boston and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803
| | - Timothy A. Springer
- Immune Disease Institute, Children's Hospital Boston and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115
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37
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Rossier O, Octeau V, Sibarita JB, Leduc C, Tessier B, Nair D, Gatterdam V, Destaing O, Albigès-Rizo C, Tampé R, Cognet L, Choquet D, Lounis B, Giannone G. Integrins β1 and β3 exhibit distinct dynamic nanoscale organizations inside focal adhesions. Nat Cell Biol 2012; 14:1057-67. [PMID: 23023225 DOI: 10.1038/ncb2588] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 08/23/2012] [Indexed: 12/12/2022]
Abstract
Integrins in focal adhesions (FAs) mediate adhesion and force transmission to extracellular matrices essential for cell motility, proliferation and differentiation. Different fibronectin-binding integrins, simultaneously present in FAs, perform distinct functions. Yet, how integrin dynamics control biochemical and biomechanical processes in FAs is still elusive. Using single-protein tracking and super-resolution imaging we revealed the dynamic nano-organizations of integrins and talin inside FAs. Integrins reside in FAs through free-diffusion and immobilization cycles. Integrin activation promotes immobilization, stabilized in FAs by simultaneous connection to fibronectin and actin-binding proteins. Talin is recruited in FAs directly from the cytosol without membrane free-diffusion, restricting integrin immobilization to FAs. Immobilized β3-integrins are enriched and stationary within FAs, whereas immobilized β1-integrins are less enriched and exhibit rearward movements. Talin is enriched and mainly stationary, but also exhibited rearward movements in FAs, consistent with stable connections with both β-integrins. Thus, differential transmission of actin motion to fibronectin occurs through specific integrins within FAs.
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Affiliation(s)
- Olivier Rossier
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, UMR 5297, F-33000 Bordeaux, France
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38
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Almaraz RT, Tian Y, Bhattarcharya R, Tan E, Chen SH, Dallas MR, Chen L, Zhang Z, Zhang H, Konstantopoulos K, Yarema KJ. Metabolic flux increases glycoprotein sialylation: implications for cell adhesion and cancer metastasis. Mol Cell Proteomics 2012; 11:M112.017558. [PMID: 22457533 PMCID: PMC3394959 DOI: 10.1074/mcp.m112.017558] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/26/2012] [Indexed: 12/14/2022] Open
Abstract
This study reports a global glycoproteomic analysis of pancreatic cancer cells that describes how flux through the sialic acid biosynthetic pathway selectively modulates a subset of N-glycosylation sites found within cellular proteins. These results provide evidence that sialoglycoprotein patterns are not determined exclusively by the transcription of biosynthetic enzymes or the availability of N-glycan sequons; instead, bulk metabolic flux through the sialic acid pathway has a remarkable ability to increase the abundance of certain sialoglycoproteins while having a minimal impact on others. Specifically, of 82 glycoproteins identified through a mass spectrometry and bioinformatics approach, ≈ 31% showed no change in sialylation, ≈ 29% exhibited a modest increase, whereas ≈ 40% experienced an increase of greater than twofold. Increased sialylation of specific glycoproteins resulted in changes to the adhesive properties of SW1990 pancreatic cancer cells (e.g. increased CD44-mediated adhesion to selectins under physiological flow and enhanced integrin-mediated cell mobility on collagen and fibronectin). These results indicate that cancer cells can become more aggressively malignant by controlling the sialylation of proteins implicated in metastatic transformation via metabolic flux.
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Affiliation(s)
| | - Yuan Tian
- §Department of Pathology, The Johns Hopkins Medical Institution
| | - Rahul Bhattarcharya
- ¶Department of Biomedical Engineering and the Translational Tissue Engineering Center, The Johns Hopkins University, Baltimore, Maryland
| | - Elaine Tan
- ¶Department of Biomedical Engineering and the Translational Tissue Engineering Center, The Johns Hopkins University, Baltimore, Maryland
| | - Shih-Hsun Chen
- From the ‡Department of Chemical and Biomolecular Engineering
| | | | - Li Chen
- §Department of Pathology, The Johns Hopkins Medical Institution
| | - Zhen Zhang
- §Department of Pathology, The Johns Hopkins Medical Institution
| | - Hui Zhang
- §Department of Pathology, The Johns Hopkins Medical Institution
| | | | - Kevin J. Yarema
- ¶Department of Biomedical Engineering and the Translational Tissue Engineering Center, The Johns Hopkins University, Baltimore, Maryland
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Qi J, Zhang K, Zhang Q, Sun Y, Fu T, Li G, Chen J. Identification, characterization, and epitope mapping of human monoclonal antibody J19 that specifically recognizes activated integrin α4β7. J Biol Chem 2012; 287:15749-59. [PMID: 22418441 DOI: 10.1074/jbc.m112.341263] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin α(4)β(7) is a lymphocyte homing receptor that mediates both rolling and firm adhesion of lymphocytes on vascular endothelium, two of the critical steps in lymphocyte migration and tissue-specific homing. The rolling and firm adhesions of lymphocytes rely on the dynamic shift between the inactive and active states of integrin α(4)β(7), which is associated with the conformational rearrangement of integrin molecules. Activation-specific antibodies, which specifically recognize the activated integrins, have been used as powerful tools in integrin studies, whereas there is no well characterized activation-specific antibody to integrin α(4)β(7). Here, we report the identification, characterization, and epitope mapping of an activation-specific human mAb J19 against integrin α(4)β(7). J19 was discovered by screening a human single-chain variable fragment phage library using an activated α(4)β(7) mutant as target. J19 IgG specifically bound to the high affinity α(4)β(7) induced by Mn(2+), DTT, ADP, or CXCL12, but not to the low affinity integrin. Moreover, J19 IgG did not interfere with α(4)β(7)-MAdCAM-1 interaction. The epitope of J19 IgG was mapped to Ser-331, Ala-332, and Ala-333 of β(7) I domain and a seven-residue segment from 184 to 190 of α(4) β-propeller domain, which are buried in low affinity integrin with bent conformation and only exposed in the high affinity extended conformation. Taken together, J19 is a potentially powerful tool for both studies on α(4)β(7) activation mechanism and development of novel therapeutics targeting the activated lymphocyte expressing high affinity α(4)β(7).
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Affiliation(s)
- JunPeng Qi
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Raborn J, Luo BH. Mutagenesis studies of the β I domain metal ion binding sites on integrin αVβ3 ligand binding affinity. J Cell Biochem 2012; 113:1190-7. [DOI: 10.1002/jcb.23448] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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41
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Mor-Cohen R, Rosenberg N, Einav Y, Zelzion E, Landau M, Mansour W, Averbukh Y, Seligsohn U. Unique disulfide bonds in epidermal growth factor (EGF) domains of β3 affect structure and function of αIIbβ3 and αvβ3 integrins in different manner. J Biol Chem 2012; 287:8879-91. [PMID: 22308022 DOI: 10.1074/jbc.m111.311043] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The β3 subunit of αIIbβ3 and αvβ3 integrins contains four epidermal growth factor (EGF)-like domains. Each domain harbors four disulfide bonds of which one is unique for integrins. We previously discerned a regulatory role of the EGF-4 Cys-560-Cys-583 unique bond for αIIbβ3 activation. In this study we further investigated the role of all four integrin unique bonds in both αIIbβ3 and αvβ3. We created β3 mutants harboring serine substitutions of each or both cysteines that disrupt the four unique bonds (Cys-437-Cys-457 in EGF-1, Cys-473-Cys-503 in EGF-2, Cys-523-Cys-544 in EGF-3, and Cys-560-Cys-583 in EGF-4) and transfected them into baby hamster kidney cells together with normal αv or αIIb. Flow cytometry was used to measure surface expression of αIIbβ3 and αvβ3 and their activity state by soluble fibrinogen binding. Most cysteine substitutions caused similarly reduced surface expression of both receptors. Disrupting all four unique disulfide bonds by single cysteine substitutions resulted in variable constitutive activation of αIIbβ3 and αvβ3. In contrast, whereas double C437S/C457S and C473S/C503S mutations yielded constitutively active αIIbβ3 and αvβ3, the C560S/C583S mutation did not, and the C523S/C544S mutation only yielded constitutively active αIIbβ3. Activation of C523S/C544S αvβ3 mutant by activating antibody and dithiothreitol was also impaired. Molecular dynamics of C523S/C544S β3 in αIIbβ3 but not in αvβ3 displayed an altered stable conformation. Our findings indicate that unique disulfide bonds in β3 differently affect the function of αIIbβ3 and αvβ3 and suggest a free sulfhydryl-dependent regulatory role for Cys-560-Cys-583 in both αIIbβ3 and αvβ3 and for Cys-523-Cys-544 only in αvβ3.
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Affiliation(s)
- Ronit Mor-Cohen
- the Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer, Israel.
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42
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Wang W, Jiang Y, Wang C, Luo BH. Effects of the Association between the α-Subunit Thigh and the β-Subunit EGF2 Domains on Integrin Activation and Signaling. Biochemistry 2011; 50:9264-72. [DOI: 10.1021/bi200744g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Wei Wang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Yan Jiang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Chen Wang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Bing-Hao Luo
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
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43
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Abstract
Integrins are integral membrane proteins that mediate cell-matrix and cell-cell adhesion. They are important for vascular development and hematopoiesis, immune and inflammatory responses, and hemostasis. Integrins are also signaling receptors that can transmit information bidirectionally across plasma membranes. Research in the past 2 decades has made progress in unraveling the mechanisms of integrin signaling and brings the field to the moment of attempting synthetic reconstruction of the signaling pathways in vitro. Reconstruction of biologic processes provides stringent tests of our understanding of the process, as evidenced by studies of other biologic machines, such as ATP synthase, lactose permease, and G-protein-coupled receptors. Here, we review recent progress in reconstructing integrin signaling and the insights that we have gained through these experiments.
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Eng ET, Smagghe BJ, Walz T, Springer TA. Intact alphaIIbbeta3 integrin is extended after activation as measured by solution X-ray scattering and electron microscopy. J Biol Chem 2011; 286:35218-26. [PMID: 21832081 DOI: 10.1074/jbc.m111.275107] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrins are bidirectional signaling molecules on the cell surface that have fundamental roles in regulating cell behavior and contribute to cell migration and adhesion. Understanding of the mechanism of integrin signaling and activation has been advanced with truncated ectodomain preparations; however, the nature of conformational change in the full-length intact integrin molecule remains an active area of research. Here we used small angle x-ray scattering and electron microscopy to study detergent-solubilized, intact platelet integrin α(IIb)β(3). In the resting state, the intact α(IIb)β(3) adopted a compact, bent conformation. Upon activation with Mn(2+), the average integrin extension increased. Further activation by addition of ligand led to stabilization of the extended state and opening of the headpiece. The observed extension and conformational rearrangement upon activation are consistent with the extension and headpiece opening model of integrin activation.
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Affiliation(s)
- Edward T Eng
- Immune Disease Institute, Children's Hospital Boston, and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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45
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Abstract
Integrins are large, membrane-spanning, heterodimeric proteins that are essential for a metazoan existence. All members of the integrin family adopt a shape that resembles a large "head" on two "legs," with the head containing the sites for ligand binding and subunit association. Most of the receptor dimer is extracellular, but both subunits traverse the plasma membrane and terminate in short cytoplasmic domains. These domains initiate the assembly of large signaling complexes and thereby bridge the extracellular matrix to the intracellular cytoskeleton. To allow cells to sample and respond to a dynamic pericellular environment, integrins have evolved a highly responsive receptor activation mechanism that is regulated primarily by changes in tertiary and quaternary structure. This review summarizes recent progress in the structural and molecular functional studies of this important class of adhesion receptor.
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Affiliation(s)
- Iain D Campbell
- Department of Biochemistry, University of Oxford, United Kingdom.
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Raborn J, Wang W, Luo BH. Regulation of integrin αIIbβ3 ligand binding and signaling by the metal ion binding sites in the β I domain. Biochemistry 2011; 50:2084-91. [PMID: 21309594 DOI: 10.1021/bi2000092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The ability of αIIbβ3 to bind ligands and undergo outside-in signaling is regulated by three divalent cation binding sites in the β I domain. Specifically, the metal ion-dependent adhesion site (MIDAS) and the synergistic metal binding site (SyMBS) are thought to be required for ligand binding due to their synergy between Ca(2+) and Mg(2+). The adjacent to MIDAS (ADMIDAS) is an important ligand binding regulatory site that also acts as a critical link between the β I and hybrid domains for signaling. Mutations in this site have provided conflicting results for ligand binding and adhesion in different integrins. We have mutated the β3 SyMBS and ADMIDAS. The SyMBS mutant abolished ligand binding and outside-in signaling, but when an activating glycosylation mutation in the αIIb Calf 2 domain was introduced, the ligand binding affinity and signaling were restored. Thus, the SyMBS is important but not absolutely required for integrin bidirectional signaling. The ADMIDAS mutants showed reduced ligand binding affinity and abolished outside-in signaling, and the activating glycosylation mutation could fully restore integrin signaling of the ADMIDAS mutant. We propose that the ADMIDAS ion stabilizes the low-affinity state when the integrin headpiece is in the closed conformation, whereas it stabilizes the high-affinity state when the headpiece is in the open conformation with the swung-out hybrid domain.
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Affiliation(s)
- Joel Raborn
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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47
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Glycans in melanoma screening. Part 2. Towards the understanding of integrin N-glycosylation in melanoma. Biochem Soc Trans 2011; 39:374-7. [DOI: 10.1042/bst0390374] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Although melanoma is one of the most studied malignancies, it still remains challenging for biomedicine. Since aberrant glycosylation has been considered as an important hallmark of cancer for many years, melanoma glycomic studies give a chance of better understanding the biology of the disease. The multistage nature of melanoma development, which is accompanied by changes in the expression of adhesion receptors from the integrin family, provides a chance for searching for neoglycoforms of proteins that can be considered as future sensitive melanoma biomarkers. The β1,6-branching, sialylation and fucosylation seem to be important modifications of integrin N-glycans in the case of malignant melanoma progression.
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Acidic extracellular pH promotes activation of integrin α(v)β(3). PLoS One 2011; 6:e15746. [PMID: 21283814 PMCID: PMC3023767 DOI: 10.1371/journal.pone.0015746] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 11/26/2010] [Indexed: 12/12/2022] Open
Abstract
Acidic extracellular pH is characteristic of the cell microenvironment in several important physiological and pathological contexts. Although it is well established that acidic extracellular pH can have profound effects on processes such as cell adhesion and migration, the underlying molecular mechanisms are largely unknown. Integrin receptors physically connect cells to the extracellular matrix, and are thus likely to modulate cell responses to extracellular conditions. Here, we examine the role of acidic extracellular pH in regulating activation of integrin αvβ3. Through computational molecular dynamics simulations, we find that acidic extracellular pH promotes opening of the αvβ3 headpiece, indicating that acidic pH can thereby facilitate integrin activation. This prediction is consistent with our flow cytometry and atomic force microscope-mediated force spectroscopy assays of integrin αvβ3 on live cells, which both demonstrate that acidic pH promotes activation at the intact cell surface. Finally, quantification of cell morphology and migration measurements shows that acidic extracellular pH affects cell behavior in a manner that is consistent with increased integrin activation. Taken together, these computational and experimental results suggest a new and complementary mechanism of integrin activation regulation, with associated implications for cell adhesion and migration in regions of altered pH that are relevant to wound healing and cancer.
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49
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Abstract
Integrins are cell adhesion molecules that play important roles in many biological processes including hemostasis, immune responses, development, and cancer. Their adhesiveness is dynamically regulated through a process termed inside-out signaling. In addition, ligand binding transduces outside-in signals from the extracellular domain to the cytoplasm. Advances in the past several years have shed light on structural basis for integrin regulation and signaling, especially how the large-scale reorientations of the ectodomain are related to the inter-domain and intra-domain shape shifting that changes ligand-binding affinity. Experiments have also shown how the conformational changes of the ectodomain are linked to changes in the α- and β-subunit transmembrane and cytoplasmic domains.
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Affiliation(s)
- Guanyuan Fu
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
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50
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Pinon P, Wehrle-Haller B. Integrins: versatile receptors controlling melanocyte adhesion, migration and proliferation. Pigment Cell Melanoma Res 2010; 24:282-94. [PMID: 21087420 DOI: 10.1111/j.1755-148x.2010.00806.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
From the onset of melanocyte specification from the neural crest, throughout their migration during embryogenesis and until they reside in their niche in the basal keratinocyte layer, melanocytes interact in dynamic ways with the extracellular environment of the growing embryo. To recognize and to adhere to their environment, melanocytes depend on heterodimeric cell surface receptors of the family of integrins. In addition to the control of adhesive interactions between melanocytes and the extracellular matrix scaffold secreted by fibroblasts and keratinocytes, the integrin receptors allow cells also to sense the mechanical condition of the extracellular environment, responding by intracellular signaling, triggering cell survival, proliferation or migration events. In this review, we summarize the recently emerged concepts that explain integrin-dependent adhesion and how this adhesion system interfaces with integrin-dependent signaling events. The gained information will help to understand melanocyte behavior in pathological situations such as melanoma growth and metastasis formation.
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Affiliation(s)
- Perrine Pinon
- Department of Cell Physiology and Metabolism, Centre Médical Universitaire, University of Geneva, Medical School, Geneva, Switzerland
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