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Adair BD, Xiong JP, Yeager M, Arnaout MA. Cryo-EM structures of full-length integrin αIIbβ3 in native lipids. Nat Commun 2023; 14:4168. [PMID: 37443315 PMCID: PMC10345127 DOI: 10.1038/s41467-023-39763-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
Platelet integrin αIIbβ3 is maintained in a bent inactive state (low affinity to physiologic ligand), but can rapidly switch to a ligand-competent (high-affinity) state in response to intracellular signals ("inside-out" activation). Once bound, ligands drive proadhesive "outside-in" signaling. Anti-αIIbβ3 drugs like eptifibatide can engage the inactive integrin directly, inhibiting thrombosis but inadvertently impairing αIIbβ3 hemostatic functions. Bidirectional αIIbβ3 signaling is mediated by reorganization of the associated αIIb and β3 transmembrane α-helices, but the underlying changes remain poorly defined absent the structure of the full-length receptor. We now report the cryo-EM structures of full-length αIIbβ3 in its apo and eptifibatide-bound states in native cell-membrane nanoparticles at near-atomic resolution. The apo form adopts the bent inactive state but with separated transmembrane α-helices, and a fully accessible ligand-binding site that challenges the model that this site is occluded by the plasma membrane. Bound eptifibatide triggers dramatic conformational changes that may account for impaired hemostasis. These results advance our understanding of integrin structure and function and may guide development of safer inhibitors.
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Affiliation(s)
- Brian D Adair
- Leukocyte Biology and Inflammation Laboratory, Structural Biology Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
- Harvard Medical School, Boston, MA, 02115, USA
| | - Jian-Ping Xiong
- Leukocyte Biology and Inflammation Laboratory, Structural Biology Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
- Harvard Medical School, Boston, MA, 02115, USA
| | - Mark Yeager
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA
- Department of Chemistry, School of Arts and Sciences, University of Miami, Coral Gables, FL 33146, University of Miami, Miami, FL, 33146, USA
- Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - M Amin Arnaout
- Leukocyte Biology and Inflammation Laboratory, Structural Biology Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA.
- Harvard Medical School, Boston, MA, 02115, USA.
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2
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Arnaout MA. INTEGRINS: A BEDSIDE TO BENCH TO BEDSIDE STORY. Trans Am Clin Climatol Assoc 2023; 133:34-55. [PMID: 37701613 PMCID: PMC10493766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
I provide a narrative of the path I took to discover the membrane receptors that mediate leukocyte adhesion, now known as β2 integrins or CD11/CD18. We followed this discovery with the first determination of the 3-D structures of integrins. The latter advance provided the foundation for understanding the unique features of integrins as divalent cation-dependent signaling receptors and as mechanosensitive conduits between the extracellular matrix and the intracellular cytoskeleton. Our structural studies are now opening new paths for taming overactive integrins in disease while minimizing the collateral damage associated with the faulty pharmacodynamics of current integrin inhibitory drugs.
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3
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Lindemann WR, Mijalis AJ, Alonso JL, Borbat PP, Freed JH, Arnaout MA, Pentelute BL, Ortony JH. Conformational Dynamics in Extended RGD-Containing Peptides. Biomacromolecules 2020; 21:2786-2794. [PMID: 32469507 PMCID: PMC7388056 DOI: 10.1021/acs.biomac.0c00506] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RGD is a prolific example of a tripeptide used in biomaterials for cell adhesion, but the potency of free or surface-bound RGD tripeptide is orders-of-magnitude less than the RGD domain within natural proteins. We designed a set of peptides with varying lengths, composed of fragments of fibronectin protein whose central three residues are RGD, in order to vary their conformational behavior without changing the binding site's chemical environment. With these peptides, we measure the conformational dynamics and transient structure of the active site. Our studies reveal how flanking residues affect conformational behavior and integrin binding. We find that disorder of the binding site is important to the potency of RGD peptides and that transient hydrogen bonding near the RGD site affects both the energy landscape roughness of the peptides and peptide binding. This phenomenon is independent of longer-range folding interactions and helps explain why short binding sequences, including RGD itself, do not fully replicate the integrin-targeting properties of extracellular matrix proteins. Our studies reinforce that peptide binding is a holistic event and fragments larger than those directly involved in binding should be considered in the design of peptide epitopes for functional biomaterials.
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Affiliation(s)
- William R Lindemann
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Alexander J Mijalis
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - José L Alonso
- Leukocyte Biology and Inflammation Program, Division of Nephrology and Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, United States
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, United States
| | - Peter P Borbat
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - M Amin Arnaout
- Leukocyte Biology and Inflammation Program, Division of Nephrology and Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, United States
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, United States
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Julia H Ortony
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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4
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Fan Z, Kiosses WB, Sun H, Orecchioni M, Ghosheh Y, Zajonc DM, Arnaout MA, Gutierrez E, Groisman A, Ginsberg MH, Ley K. High-Affinity Bent β 2-Integrin Molecules in Arresting Neutrophils Face Each Other through Binding to ICAMs In cis. Cell Rep 2020; 26:119-130.e5. [PMID: 30605669 PMCID: PMC6625519 DOI: 10.1016/j.celrep.2018.12.038] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/09/2018] [Accepted: 12/07/2018] [Indexed: 01/13/2023] Open
Abstract
Leukocyte adhesion requires β2-integrin activation. Resting integrins exist in a bent-closed conformation-i.e., not extended (E-) and not high affinity (H-)-unable to bind ligand. Fully activated E+H+ integrin binds intercellular adhesion molecules (ICAMs) expressed on the opposing cell in trans. E-H- transitions to E+H+ through E+H- or through E-H+, which binds to ICAMs on the same cell in cis. Spatial patterning of activated integrins is thought to be required for effective arrest, but no high-resolution cell surface localization maps of activated integrins exist. Here, we developed Super-STORM by combining super-resolution microscopy with molecular modeling to precisely localize activated integrin molecules and identify the molecular patterns of activated integrins on primary human neutrophils. At the time of neutrophil arrest, E-H+ integrins face each other to form oriented (non-random) nanoclusters. To address the mechanism causing this pattern, we blocked integrin binding to ICAMs in cis, which significantly relieved the face-to-face orientation.
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Affiliation(s)
- Zhichao Fan
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - William Bill Kiosses
- Microscopy Core Facility, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Hao Sun
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Marco Orecchioni
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Yanal Ghosheh
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Dirk M Zajonc
- Division of Immune Regulation, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA; Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, 9000 Ghent, Belgium
| | - M Amin Arnaout
- Harvard Medical School, Boston, MA 02115, USA; Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Boston, MA 02114, USA; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Center for Regenerative Medicine, Medical Services, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Edgar Gutierrez
- Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Alex Groisman
- Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA; Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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5
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Li J, Fukase Y, Shang Y, Zou W, Muñoz-Félix JM, Buitrago L, van Agthoven J, Zhang Y, Hara R, Tanaka Y, Okamoto R, Yasui T, Nakahata T, Imaeda T, Aso K, Zhou Y, Locuson C, Nesic D, Duggan M, Takagi J, Vaughan RD, Walz T, Hodivala-Dilke K, Teitelbaum SL, Arnaout MA, Filizola M, Foley MA, Coller BS. Novel Pure αVβ3 Integrin Antagonists That Do Not Induce Receptor Extension, Prime the Receptor, or Enhance Angiogenesis at Low Concentrations. ACS Pharmacol Transl Sci 2019; 2:387-401. [PMID: 32259072 DOI: 10.1021/acsptsci.9b00041] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Indexed: 01/12/2023]
Abstract
The integrin αVβ3 receptor has been implicated in several important diseases, but no antagonists are approved for human therapy. One possible limitation of current small-molecule antagonists is their ability to induce a major conformational change in the receptor that induces it to adopt a high-affinity ligand-binding state. In response, we used structural inferences from a pure peptide antagonist to design the small-molecule pure antagonists TDI-4161 and TDI-3761. Both compounds inhibit αVβ3-mediated cell adhesion to αVβ3 ligands, but do not induce the conformational change as judged by antibody binding, electron microscopy, X-ray crystallography, and receptor priming studies. Both compounds demonstrated the favorable property of inhibiting bone resorption in vitro, supporting potential value in treating osteoporosis. Neither, however, had the unfavorable property of the αVβ3 antagonist cilengitide of paradoxically enhancing aortic sprout angiogenesis at concentrations below its IC50, which correlates with cilengitide's enhancement of tumor growth in vivo.
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Affiliation(s)
- Jihong Li
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Yoshiyuki Fukase
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Yi Shang
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1677, New York, New York 10029-6574, United States
| | - Wei Zou
- Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
| | - José M Muñoz-Félix
- Adhesion and Angiogenesis Laboratory, Centre for Tumour Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London, EC1M 6BQ, United Kingdom
| | - Lorena Buitrago
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Johannes van Agthoven
- Leukocyte Biology and Inflammation and Structural Biology Programs, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Yixiao Zhang
- Laboratory of Molecular Electron Microscopy, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Ryoma Hara
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Yuta Tanaka
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Rei Okamoto
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Takeshi Yasui
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Takashi Nakahata
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Toshihiro Imaeda
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Kazuyoshi Aso
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Yuchen Zhou
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1677, New York, New York 10029-6574, United States
| | - Charles Locuson
- Agios Pharmaceuticals, 88 Sidney Street, Cambridge, Massachusetts 02139-4169, United States
| | - Dragana Nesic
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Mark Duggan
- LifeSci Consulting, LLC, 18243 SE Ridgeview Drive, Tequesta, Florida 33469, United States
| | - Junichi Takagi
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Roger D Vaughan
- Rockefeller University Center for Clinical and Translational Science, Rockefeller University, 2130 York Avenue, New York, New York 10065, United States
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Kairbaan Hodivala-Dilke
- Adhesion and Angiogenesis Laboratory, Centre for Tumour Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London, EC1M 6BQ, United Kingdom
| | - Steven L Teitelbaum
- Washington University School of Medicine, Campus Box 8118, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
| | - M Amin Arnaout
- Leukocyte Biology and Inflammation and Structural Biology Programs, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1677, New York, New York 10029-6574, United States
| | - Michael A Foley
- Tri-Institutional Therapeutics Discovery Institute, 413 East 69 Street, New York, New York 10021, United States
| | - Barry S Coller
- Allen and Frances Adler Laboratory of Blood and Vascular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
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6
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Van Agthoven JF, Shams H, Cochran FV, Alonso JL, Kintzing JR, Garakani K, Adair BD, Xiong JP, Mofrad MRK, Cochran JR, Arnaout MA. Structural Basis of the Differential Binding of Engineered Knottins to Integrins αVβ3 and α5β1. Structure 2019; 27:1443-1451.e6. [PMID: 31353240 DOI: 10.1016/j.str.2019.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/29/2019] [Accepted: 06/28/2019] [Indexed: 01/06/2023]
Abstract
Targeting both integrins αVβ3 and α5β1 simultaneously appears to be more effective in cancer therapy than targeting each one alone. The structural requirements for bispecific binding of ligand to integrins have not been fully elucidated. RGD-containing knottin 2.5F binds selectively to αVβ3 and α5β1, whereas knottin 2.5D is αVβ3 specific. To elucidate the structural basis of this selectivity, we determined the structures of 2.5F and 2.5D as apo proteins and in complex with αVβ3, and compared their interactions with integrins using molecular dynamics simulations. These studies show that 2.5D engages αVβ3 by an induced fit, but conformational selection of a flexible RGD loop accounts for high-affinity selective binding of 2.5F to both integrins. The contrasting binding of the highly flexible low-affinity linear RGD peptides to multiple integrins suggests that a "Goldilocks zone" of conformational flexibility of the RGD loop in 2.5F underlies its selective binding promiscuity to integrins.
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Affiliation(s)
- Johannes F Van Agthoven
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Division of Nephrology/Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Hengameh Shams
- Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA 94720, USA
| | - Frank V Cochran
- Departments of Bioengineering and Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - José L Alonso
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Division of Nephrology/Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - James R Kintzing
- Departments of Bioengineering and Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Kiavash Garakani
- Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA 94720, USA
| | - Brian D Adair
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Division of Nephrology/Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Jian-Ping Xiong
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Division of Nephrology/Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Mohammad R K Mofrad
- Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA 94720, USA
| | - Jennifer R Cochran
- Departments of Bioengineering and Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - M Amin Arnaout
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Division of Nephrology/Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
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7
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Wei C, Li J, Adair BD, Zhu K, Cai J, Merchant M, Samelko B, Liao Z, Koh KH, Tardi NJ, Dande RR, Liu S, Ma J, Dibartolo S, Hägele S, Peev V, Hayek SS, Cimbaluk DJ, Tracy M, Klein J, Sever S, Shattil SJ, Arnaout MA, Reiser J. uPAR isoform 2 forms a dimer and induces severe kidney disease in mice. J Clin Invest 2019; 129:1946-1959. [PMID: 30730305 DOI: 10.1172/jci124793] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/05/2019] [Indexed: 12/12/2022] Open
Abstract
Soluble urokinase plasminogen activator receptor (suPAR) is an immune-derived circulating signaling molecule that has been implicated in chronic kidney disease, such as focal segmental glomerulosclerosis (FSGS). Typically, native uPAR (isoform 1) translates to a 3-domain protein capable of binding and activating integrins, yet the function of additional isoforms generated by alternative splicing is unknown. Here, we characterized mouse uPAR isoform 2 (msuPAR2), encoding domain I and nearly one-half of domain II, as a dimer in solution, as revealed by 3D electron microscopy structural analysis. In vivo, msuPAR2 transgenic mice exhibited signs of severe renal disease characteristic of FSGS with proteinuria, loss of kidney function, and glomerulosclerosis. Sequencing of the glomerular RNAs from msuPAR2-Tg mice revealed a differentially expressed gene signature that includes upregulation of the suPAR receptor Itgb3, encoding β3 integrin. Crossing msuPAR2-transgenic mice with 3 different integrin β3 deficiency models rescued msuPAR2-mediated kidney function. Further analyses indicated a central role for β3 integrin and c-Src in msuPAR2 signaling and in human FSGS kidney biopsies. Administration of Src inhibitors reduced proteinuria in msuPAR2-transgenic mice. In conclusion, msuPAR2 may play an important role in certain forms of scarring kidney disease.
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Affiliation(s)
- Changli Wei
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jing Li
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Brian D Adair
- Harvard Medical School, Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Ke Zhu
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jian Cai
- University of Louisville, Louisville, Kentucky, USA
| | | | - Beata Samelko
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Zhongji Liao
- Department of Medicine, UCSD, La Jolla, California, USA
| | - Kwi Hye Koh
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Nicholas J Tardi
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Ranadheer R Dande
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Shuangxin Liu
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jianchao Ma
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Salvatore Dibartolo
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Stefan Hägele
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Vasil Peev
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Salim S Hayek
- University of Michigan Frankel Cardiovascular Center, Ann Arbor, Michigan, USA
| | - David J Cimbaluk
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
| | - Melissa Tracy
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jon Klein
- University of Louisville, Louisville, Kentucky, USA
| | - Sanja Sever
- Harvard Medical School, Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | | | - M Amin Arnaout
- Harvard Medical School, Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
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8
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Abstract
In the kidney, the renal proximal tubule (PT) reabsorbs solutes into the peritubular capillaries through active transport. Here, we replicate this reabsorptive function in vitro by engineering a microfluidic PT. The microfluidic PT architecture comprises a porous membrane with user-defined submicron surface topography separating two microchannels representing a PT filtrate lumen and a peritubular capillary lumen. Human PT epithelial cells and microvascular endothelial cells in respective microchannels created a PT-like reabsorptive barrier. Co-culturing epithelial and endothelial cells in the microfluidic architecture enhanced viability, metabolic activity, and compactness of the epithelial layer. The resulting tissue expressed tight junctions, kidney-specific morphology, and polarized expression of kidney markers. The microfluidic PT actively performed sodium-coupled glucose transport, which could be modulated by administration of a sodium-transport inhibiting drug. The microfluidic PT reproduces human physiology at the cellular and tissue levels, and measurable tissue function which can quantify kidney pharmaceutical efficacy and toxicity.
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Affiliation(s)
- Else M. Vedula
- Biomedical Microsystems Group, Draper, Cambridge, Massachusetts, United States of America
| | - José Luis Alonso
- Leukocyte Biology and Inflammation Program, Department of Medicine, Nephrology Division, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - M. Amin Arnaout
- Leukocyte Biology and Inflammation Program, Department of Medicine, Nephrology Division, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
- * E-mail: (JLC); (MAA)
| | - Joseph L. Charest
- Biomedical Microsystems Group, Draper, Cambridge, Massachusetts, United States of America
- * E-mail: (JLC); (MAA)
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9
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Dehnadi A, Benedict Cosimi A, Neal Smith R, Li X, Alonso JL, Means TK, Arnaout MA. Prophylactic orthosteric inhibition of leukocyte integrin CD11b/CD18 prevents long-term fibrotic kidney failure in cynomolgus monkeys. Nat Commun 2017; 8:13899. [PMID: 28071653 PMCID: PMC5234083 DOI: 10.1038/ncomms13899] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/10/2016] [Indexed: 12/21/2022] Open
Abstract
Ischaemic acute kidney injury (AKI), an inflammatory disease process, often progresses to chronic kidney disease (CKD), with no available effective prophylaxis. This is in part due to lack of clinically relevant CKD models in non-human primates. Here we demonstrate that inhibition of the archetypal innate immune receptor CD11b/CD18 prevents progression of AKI to CKD in cynomolgus monkeys. Severe ischaemia-reperfusion injury of the right kidney, with subsequent periods of the left ureter ligation, causes irreversible right kidney failure 3, 6 or 9 months after AKI. Moreover, prophylactic inactivation of CD11b/CD18, using the orthosteric CD11b/CD18 inhibitor mAb107, improves microvascular perfusion and histopathology, reduces intrarenal pro-inflammatory mediators and salvages kidney function long term. These studies reveal an important early role of CD11b+ leukocytes in post-ischaemic kidney fibrosis and failure, and suggest a potential early therapeutic intervention to mitigate progression of ischaemic AKI to CKD in humans.
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Affiliation(s)
- Abbas Dehnadi
- Division of Transplant Surgery, Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - A Benedict Cosimi
- Division of Transplant Surgery, Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rex Neal Smith
- Harvard Medical School, Boston, Massachusetts 02115, USA.,Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Xiangen Li
- Harvard Medical School, Boston, Massachusetts 02115, USA.,Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - José L Alonso
- Harvard Medical School, Boston, Massachusetts 02115, USA.,Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Terry K Means
- Harvard Medical School, Boston, Massachusetts 02115, USA.,Division of Rheumatology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - M Amin Arnaout
- Harvard Medical School, Boston, Massachusetts 02115, USA.,Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Center For Regenerative Medicine, Medical Services, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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10
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Abstract
Integrins comprise a large family of αβ heterodimeric cell adhesion receptors that are expressed on all cells except red blood cells and that play essential roles in the regulation of cell growth and function. The leukocyte integrins, which include members of the β
1, β
2, β
3, and β
7 integrin family, are critical for innate and adaptive immune responses but also can contribute to many inflammatory and autoimmune diseases when dysregulated. This review focuses on the β
2 integrins, the principal integrins expressed on leukocytes. We review their discovery and role in host defense, the structural basis for their ligand recognition and activation, and their potential as therapeutic targets.
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Affiliation(s)
- M Amin Arnaout
- Leukocyte Biology & Inflammation Program, Structural Biology Program, Nephrology, Center for Regenerative Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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11
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Wu Q, Zhang J, Koh W, Yu Q, Zhu X, Amsterdam A, Davis GE, Arnaout MA, Xiong JW. Talin1 is required for cardiac Z-disk stabilization and endothelial integrity in zebrafish. FASEB J 2015; 29:4989-5005. [PMID: 26310270 DOI: 10.1096/fj.15-273409] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 08/13/2015] [Indexed: 01/20/2023]
Abstract
Talin (tln) binds and activates integrins to couple extracellular matrix-bound integrins to the cytoskeleton; however, its role in heart development is not well characterized. We identified the defective gene and the resulting cardiovascular phenotypes in zebrafish tln1(fl02k) mutants. The ethylnitrosourea-induced fl02k mutant showed heart failure, brain hemorrhage, and diminished cardiac and vessel lumens at 52 h post fertilization. Positional cloning revealed a nonsense mutation of tln1 in this mutant. tln1, but neither tln2 nor -2a, was dominantly expressed in the heart and vessels. Unlike tln1 and -2 in the mouse heart, the unique tln1 expression in the heart enabled us, for the first time, to determine the critical roles of Tln1 in the maintenance of cardiac sarcomeric Z-disks and endothelial/endocardial cell integrity, partly through regulating F-actin networks in zebrafish. The similar expression profiles of tln1 and integrin β1b (itgb1b) and synergistic function of the 2 genes revealed that itgb1b is a potential partner for tln1 in the stabilization of cardiac Z-disks and vessel lumens. Taken together, the results of this work suggest that Tln1-mediated Itgβ1b plays a crucial role in maintaining cardiac sarcomeric Z-disks and endothelial/endocardial cell integrity in zebrafish and may also help to gain molecular insights into congenital heart diseases.
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Affiliation(s)
- Qing Wu
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jiaojiao Zhang
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Wonshill Koh
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Qingming Yu
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Xiaojun Zhu
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Adam Amsterdam
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - George E Davis
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - M Amin Arnaout
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jing-Wei Xiong
- *Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, China; Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Medical Pharmacology and Department of Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA; and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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12
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Zhang J, Yuan S, Vasilyev A, Amin Arnaout M. The transcriptional coactivator Taz regulates proximodistal patterning of the pronephric tubule in zebrafish. Mech Dev 2015; 138 Pt 3:328-35. [PMID: 26248207 DOI: 10.1016/j.mod.2015.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 07/27/2015] [Accepted: 08/01/2015] [Indexed: 01/09/2023]
Abstract
The zebrafish pronephric tubule consists of proximal and distal segments and a collecting duct. The proximal segment is subdivided into the neck, proximal convoluted tubule (PCT) and proximal straight tubule (PST) segments. The distal segment consists of the distal-early (DE) and distal-late (DL) segments. How the proximal and distal segments develop along the anteroposterior axis is poorly understood. Here we show that knockdown of taz in zebrafish caused shortening and a significant reduction in the number of principal cells of the PST-DE segment, and proximalization of the pronephric tubule in 24 hpf embryos. RA treatment expanded the pronephric proximal domain in normal embryos as in taz morphants, an effect that was further enhanced upon exposure of taz morphants to RA. The early pronephric defects in 24 hpf taz morphants led to the failure of anterior pronephric tubule migration and convolution, and to PCT dilation and cyst formation in older embryos. In situ hybridization showed weak and transient expression of taz at the bud stage in the intermediate mesoderm, the source of pronephric progenitors. The present findings show that Taz is required in the anteroposterior patterning of the pronephric progenitor domain in the intermediate mesoderm, acting in part by regulating RA signaling in the pronephric progenitor field in the intermediate mesoderm.
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Affiliation(s)
- Jiaojiao Zhang
- Leukocyte Biology & Inflammation Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, United States
| | - Shipeng Yuan
- Leukocyte Biology & Inflammation Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, United States
| | - Aleksandr Vasilyev
- Leukocyte Biology & Inflammation Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, United States; Department of Pathology, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, United States
| | - M Amin Arnaout
- Leukocyte Biology & Inflammation Program, Division of Nephrology, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, United States; Department of Developmental and Regenerative Biology, Harvard Medical School, Boston, MA 02115, United States.
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13
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Camarata TD, Weaver GC, Vasilyev A, Arnaout MA. Negative Regulation of TGFβ Signaling by Stem Cell Antigen-1 Protects against Ischemic Acute Kidney Injury. PLoS One 2015; 10:e0129561. [PMID: 26053644 PMCID: PMC4460127 DOI: 10.1371/journal.pone.0129561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/10/2015] [Indexed: 12/22/2022] Open
Abstract
Acute kidney injury, often caused by an ischemic insult, is associated with significant short-term morbidity and mortality, and increased risk of chronic kidney disease. The factors affecting the renal response to injury following ischemia and reperfusion remain to be clarified. We found that the Stem cell antigen-1 (Sca-1), commonly used as a stem cell marker, is heavily expressed in renal tubules of the adult mouse kidney. We evaluated its potential role in the kidney using Sca-1 knockout mice submitted to acute ischemia reperfusion injury (IRI), as well as cultured renal proximal tubular cells in which Sca-1 was stably silenced with shRNA. IRI induced more severe injury in Sca-1 null kidneys, as assessed by increased expression of Kim-1 and Ngal, rise in serum creatinine, abnormal pathology, and increased apoptosis of tubular epithelium, and persistent significant renal injury at day 7 post IRI, when recovery of renal function in control animals was nearly complete. Serum creatinine, Kim-1 and Ngal were slightly but significantly elevated even in uninjured Sca-1-/- kidneys. Sca-1 constitutively bound both TGFβ receptors I and II in cultured normal proximal tubular epithelial cells. Its genetic loss or silencing lead to constitutive TGFβ receptor—mediated activation of canonical Smad signaling even in the absence of ligand and to KIM-1 expression in the silenced cells. These studies demonstrate that by normally repressing TGFβ-mediated canonical Smad signaling, Sca-1 plays an important in renal epithelial cell homeostasis and in recovery of renal function following ischemic acute kidney injury.
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Affiliation(s)
- Troy D. Camarata
- Leukocyte Biology & Inflammation Program, Renal Division and Department of Medicine Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Grant C. Weaver
- Leukocyte Biology & Inflammation Program, Renal Division and Department of Medicine Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Alexandr Vasilyev
- Leukocyte Biology & Inflammation Program, Renal Division and Department of Medicine Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - M. Amin Arnaout
- Leukocyte Biology & Inflammation Program, Renal Division and Department of Medicine Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Center For Regenerative Medicine, Department of Medicine, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- * E-mail:
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14
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Li X, Romain RD, Park D, Scadden DT, Merchant JL, Arnaout MA. Stress hematopoiesis is regulated by the Krüppel-like transcription factor ZBP-89. Stem Cells 2014; 32:791-801. [PMID: 24549639 DOI: 10.1002/stem.1598] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 09/18/2013] [Accepted: 10/07/2013] [Indexed: 11/09/2022]
Abstract
Previous studies have shown that ZBP-89 (Zfp148) plays a critical role in erythroid lineage development, with its loss at the embryonic stage causing lethal anemia and thrombocytopenia. Its role in adult hematopoiesis has not been described. We now show that conditional deletion of ZBP-89 in adult mouse hematopoietic stem/progenitor cells (HSPC) causes anemia and thrombocytopenia that are transient in the steady state, but readily uncovered following chemically induced erythro/megakaryopoietic stress. Unexpectedly, stress induced by bone marrow transplantation of ZBP89(-/-) HSPC also resulted in a myeloid-to-B lymphoid lineage switch in bone marrow recipients. The erythroid and myeloid/B lymphoid lineage anomalies in ZBP89(-/-) HSPC are reproduced in vitro in the ZBP-89-silenced multipotent hematopoietic cell line FDCP-Mix A4, and are associated with the upregulation of PU.1 and downregulation of SCL/Tal1 and GATA-1 in ZBP89-deficient cells. Chromatin immunoprecipitation and luciferase reporter assays show that ZBP-89 is a direct repressor of PU.1 and activator of SCL/Tal1 and GATA-1. These data identify an important role for ZBP-89 in regulating stress hematopoiesis in adult mouse bone marrow.
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Affiliation(s)
- Xiangen Li
- Leukocyte Biology & Inflammation Program, Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
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15
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Palmyre A, Lee J, Ryklin G, Camarata T, Selig MK, Duchemin AL, Nowak P, Arnaout MA, Drummond IA, Vasilyev A. Collective epithelial migration drives kidney repair after acute injury. PLoS One 2014; 9:e101304. [PMID: 25010471 PMCID: PMC4092191 DOI: 10.1371/journal.pone.0101304] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 06/04/2014] [Indexed: 02/07/2023] Open
Abstract
Acute kidney injury (AKI) is a common and significant medical problem. Despite the kidney’s remarkable regenerative capacity, the mortality rate for the AKI patients is high. Thus, there remains a need to better understand the cellular mechanisms of nephron repair in order to develop new strategies that would enhance the intrinsic ability of kidney tissue to regenerate. Here, using a novel, laser ablation-based, zebrafish model of AKI, we show that collective migration of kidney epithelial cells is a primary early response to acute injury. We also show that cell proliferation is a late response of regenerating kidney epithelia that follows cell migration during kidney repair. We propose a computational model that predicts this temporal relationship and suggests that cell stretch is a mechanical link between migration and proliferation, and present experimental evidence in support of this hypothesis. Overall, this study advances our understanding of kidney repair mechanisms by highlighting a primary role for collective cell migration, laying a foundation for new approaches to treatment of AKI.
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Affiliation(s)
- Aurélien Palmyre
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Jeongeun Lee
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Biomedical Sciences, NYIT COM, Old Westbury, New York, United States of America
| | - Gennadiy Ryklin
- Department of Biomedical Sciences, NYIT COM, Old Westbury, New York, United States of America
| | - Troy Camarata
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Martin K. Selig
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Anne-Laure Duchemin
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Paul Nowak
- Department of Biomedical Sciences, NYIT COM, Old Westbury, New York, United States of America
| | - M. Amin Arnaout
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Developmental and Regenerative Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Iain A. Drummond
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Aleksandr Vasilyev
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Biomedical Sciences, NYIT COM, Old Westbury, New York, United States of America
- * E-mail:
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16
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Rui X, Mehrbod M, Van Agthoven JF, Anand S, Xiong JP, Mofrad MRK, Arnaout MA. The α-subunit regulates stability of the metal ion at the ligand-associated metal ion-binding site in β3 integrins. J Biol Chem 2014; 289:23256-23263. [PMID: 24975416 DOI: 10.1074/jbc.m114.581470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aspartate in the prototypical integrin-binding motif Arg-Gly-Asp binds the integrin βA domain of the β-subunit through a divalent cation at the metal ion-dependent adhesion site (MIDAS). An auxiliary metal ion at a ligand-associated metal ion-binding site (LIMBS) stabilizes the metal ion at MIDAS. LIMBS contacts distinct residues in the α-subunits of the two β3 integrins αIIbβ3 and αVβ3, but a potential role of this interaction on stability of the metal ion at LIMBS in β3 integrins has not been explored. Equilibrium molecular dynamics simulations of fully hydrated β3 integrin ectodomains revealed strikingly different conformations of LIMBS in unliganded αIIbβ3 versus αVβ3, the result of stronger interactions of LIMBS with αV, which reduce stability of the LIMBS metal ion in αVβ3. Replacing the αIIb-LIMBS interface residue Phe(191) in αIIb (equivalent to Trp(179) in αV) with Trp strengthened this interface and destabilized the metal ion at LIMBS in αIIbβ3; a Trp(179) to Phe mutation in αV produced the opposite but weaker effect. Consistently, an F191/W substitution in cellular αIIbβ3 and a W179/F substitution in αVβ3 reduced and increased, respectively, the apparent affinity of Mn(2+) to the integrin. These findings offer an explanation for the variable occupancy of the metal ion at LIMBS in αVβ3 structures in the absence of ligand and provide new insights into the mechanisms of integrin regulation.
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Affiliation(s)
- Xianliang Rui
- Leukocyte Biology and Inflammation Program and Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Mehrdad Mehrbod
- Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720
| | - Johannes F Van Agthoven
- Structural Biology Program, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129 and
| | - Saurabh Anand
- Leukocyte Biology and Inflammation Program and Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Jian-Ping Xiong
- Structural Biology Program, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129 and
| | - Mohammad R K Mofrad
- Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720.
| | - M Amin Arnaout
- Leukocyte Biology and Inflammation Program and Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129; Structural Biology Program, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129 and.
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17
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Van Agthoven JF, Xiong JP, Alonso JL, Rui X, Adair BD, Goodman SL, Arnaout MA. Structural basis for pure antagonism of integrin αVβ3 by a high-affinity form of fibronectin. Nat Struct Mol Biol 2014; 21:383-8. [PMID: 24658351 PMCID: PMC4012256 DOI: 10.1038/nsmb.2797] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/24/2014] [Indexed: 01/07/2023]
Abstract
Integrins are important therapeutic targets. However, current RGD-based anti-integrin drugs are also partial agonists, inducing conformational changes that trigger potentially fatal immune reactions and paradoxical cell adhesion. Here we describe the first crystal structure of αVβ3 bound to a physiologic ligand, the tenth type III RGD domain of wild-type fibronectin (wtFN10), or to a high-affinity mutant (hFN10) shown here to act as a pure antagonist. Comparison of these structures revealed a central π-π interaction between Trp1496 in the RGD-containing loop of hFN10 and Tyr122 of the β3 subunit that blocked conformational changes triggered by wtFN10 and trapped hFN10-bound αVβ3 in an inactive conformation. Removing the Trp1496 or Tyr122 side chains or reorienting Trp1496 away from Tyr122 converted hFN10 into a partial agonist. These findings offer new insights into the mechanism of integrin activation and a basis for the design of RGD-based pure antagonists.
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Affiliation(s)
- Johannes F. Van Agthoven
- Structural Biology Program, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
| | - Jian-Ping Xiong
- Structural Biology Program, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
| | - José Luis Alonso
- Leukocyte Biology & Inflammation Program, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
| | - Xianliang Rui
- Leukocyte Biology & Inflammation Program, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
| | - Brian D. Adair
- Structural Biology Program, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
| | - Simon L. Goodman
- Harvard Medical School, Global Research and Early Development, Translational Innovation platform, Oncology, Merck KGaA, Darmstadt 64271, Germany
| | - M. Amin Arnaout
- Structural Biology Program, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129,Leukocyte Biology & Inflammation Program, Department of Medicine, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129
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18
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Mahalingam B, Van Agthoven JF, Xiong JP, Alonso JL, Adair BD, Rui X, Anand S, Mehrbod M, Mofrad MRK, Burger C, Goodman SL, Arnaout MA. Atomic basis for the species-specific inhibition of αV integrins by monoclonal antibody 17E6 is revealed by the crystal structure of αVβ3 ectodomain-17E6 Fab complex. J Biol Chem 2014; 289:13801-9. [PMID: 24692540 DOI: 10.1074/jbc.m113.546929] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The function-blocking, non-RGD-containing, and primate-specific mouse monoclonal antibody 17E6 binds the αV subfamily of integrins. 17E6 is currently in phase II clinical trials for treating cancer. To elucidate the structural basis of recognition and the molecular mechanism of inhibition, we crystallized αVβ3 ectodomain in complex with the Fab fragment of 17E6. Protein crystals grew in presence of the activating cation Mn(2+). The integrin in the complex and in solution assumed the genuflected conformation. 17E6 Fab bound exclusively to the Propeller domain of the αV subunit. At the core of αV-Fab interface were interactions involving Propeller residues Lys-203 and Gln-145, with the latter accounting for primate specificity. The Propeller residue Asp-150, which normally coordinates Arg of the ligand Arg-Gly-Asp motif, formed contacts with Arg-54 of the Fab that were expected to reduce soluble FN10 binding to cellular αVβ3 complexed with 17E6. This was confirmed in direct binding studies, suggesting that 17E6 is an allosteric inhibitor of αV integrins.
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Affiliation(s)
| | | | | | - José Luis Alonso
- the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | | | - Xianliang Rui
- the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Saurabh Anand
- the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Mehrdad Mehrbod
- the Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720
| | - Mohammad R K Mofrad
- the Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720
| | - Christa Burger
- Merck KGaA and Discovery Technologies, Molecular Pharmacology, and
| | - Simon L Goodman
- Merck KGaA and Therapeutic Innovation Platform, Oncology, Darmstadt 64271, Germany
| | - M Amin Arnaout
- From the Structural Biology Program and the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129,
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19
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Adair BD, Altintas MM, Möller CC, Arnaout MA, Reiser J. Structure of the kidney slit diaphragm adapter protein CD2-associated protein as determined with electron microscopy. J Am Soc Nephrol 2014; 25:1465-73. [PMID: 24511139 DOI: 10.1681/asn.2013090949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
CD2-associated protein (CD2AP) is a multidomain scaffolding protein that has a critical role in renal function. CD2AP is expressed in glomerular podocytes at the slit diaphragm, a modified adherens junction that comprises the protein filtration barrier of the kidney, and interacts with a number of protein ligands involved in cytoskeletal remodeling, membrane trafficking, cell motility, and cell survival. The structure of CD2AP is unknown. We used electron microscopy and single particle image analysis to determine the three-dimensional structure of recombinant full-length CD2AP and found that the protein is a tetramer in solution. Image reconstruction of negatively stained protein particles generated a structure at 21 Å resolution. The protein assumed a roughly spherical, very loosely packed structure. Analysis of the electron density map revealed that CD2AP consists of a central coiled-coil domain, which forms the tetramer interface, surrounded by four symmetry-related motifs, each containing three globular domains corresponding to the three SH3 domains. The spatial organization exposes the binding sites of all 12 SH3 domains in the tetramer, allowing simultaneous binding to multiple targets. Determination of the structure of CD2AP provides novel insights into the biology of this slit diaphragm protein and lays the groundwork for characterizing the interactions between key molecules of the slit diaphragm that control glomerular filtration.
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Affiliation(s)
- Brian D Adair
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, Illinois; and
| | - Clemens C Möller
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - M Amin Arnaout
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Developmental and Regenerative Biology, Harvard Medical School, Boston, Massachusetts
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, Illinois; and
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20
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Yu CC, Fornoni A, Weins A, Hakroush S, Maiguel D, Sageshima J, Chen L, Ciancio G, Faridi MH, Behr D, Campbell KN, Chang JM, Chen HC, Oh J, Faul C, Arnaout MA, Fiorina P, Gupta V, Greka A, Burke GW, Mundel P. Abatacept in B7-1-positive proteinuric kidney disease. N Engl J Med 2013; 369:2416-23. [PMID: 24206430 PMCID: PMC3951406 DOI: 10.1056/nejmoa1304572] [Citation(s) in RCA: 274] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abatacept (cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin fusion protein [CTLA-4-Ig]) is a costimulatory inhibitor that targets B7-1 (CD80). The present report describes five patients who had focal segmental glomerulosclerosis (FSGS) (four with recurrent FSGS after transplantation and one with primary FSGS) and proteinuria with B7-1 immunostaining of podocytes in kidney-biopsy specimens. Abatacept induced partial or complete remissions of proteinuria in these patients, suggesting that B7-1 may be a useful biomarker for the treatment of some glomerulopathies. Our data indicate that abatacept may stabilize β1-integrin activation in podocytes and reduce proteinuria in patients with B7-1-positive glomerular disease.
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Affiliation(s)
- Chih-Chuan Yu
- From the Department of Medicine, Massachusetts General Hospital and Harvard Medical School (C.-C.Y., A.W., S.H., D.B., M.A.A., A.G., P.M.), Department of Pathology, Brigham and Women's Hospital and Harvard Medical School (A.W.), and Division of Nephrology, Children's Hospital Boston (P.F.) - all in Boston; the Graduate Institute of Medicine, College of Medicine (C.-C.Y.), and Department of Internal Medicine (J.-M.C., H.-C.C.), Kaohsiung Medical University, Kaohsiung, Taiwan; the Division of Nephrology and Hypertension (A.F., D.M., M.H.F., C.F., V.G.) and Lilian Jean Kaplan Division of Kidney-Pancreas Transplantation, Miami Transplant Institute, Department of Surgery (J.S., L.C., G.C., G.W.B.), University of Miami Miller School of Medicine, Miami; the Division of Nephrology, Mount Sinai School of Medicine, New York (K.N.C.); and Pediatric Nephrology, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (J.O.)
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21
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Frohlich EM, Alonso JL, Borenstein JT, Zhang X, Arnaout MA, Charest JL. Topographically-patterned porous membranes in a microfluidic device as an in vitro model of renal reabsorptive barriers. Lab Chip 2013; 13:2311-9. [PMID: 23636129 PMCID: PMC4578304 DOI: 10.1039/c3lc50199j] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Models of reabsorptive barriers require both a means to provide realistic physiologic cues to and quantify transport across a layer of cells forming the barrier. Here we have topographically-patterned porous membranes with several user-defined pattern types. To demonstrate the utility of the patterned membranes, we selected one type of pattern and applied it to a membrane to serve as a cell culture support in a microfluidic model of a renal reabsorptive barrier. The topographic cues in the model resemble physiological cues found in vivo while the porous structure allows quantification of transport across the cell layer. Sub-micron surface topography generated via hot-embossing onto a track-etched polycarbonate membrane, fully replicated topographical features and preserved porous architecture. Pore size and shape were analyzed with SEM and image analysis to determine the effect of hot embossing on pore morphology. The membrane was assembled into a bilayer microfluidic device and a human kidney proximal tubule epithelial cell line (HK-2) and primary renal proximal tubule epithelial cells (RPTEC) were cultured to confluency on the membrane. Immunofluorescent staining of both cell types revealed protein expression indicative of the formation of a reabsorptive barrier responsive to mechanical stimulation: ZO-1 (tight junction), paxillin (focal adhesions) and acetylated α-tubulin (primary cilia). HK-2 and RPTEC aligned in the direction of ridge/groove topography of the membrane in the device, evidence that the device has mechanical control over cell response. This topographically-patterned porous membrane provides an in vitro platform on which to model reabsorptive barriers with meaningful applications for understanding biological transport phenomenon, underlying disease mechanisms, and drug toxicity.
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Affiliation(s)
- Else M. Frohlich
- Boston University, Department of Mechanical Engineering, 110 Cummington Street, Boston, MA 02215, USA
- Charles Stark Draper Laboratory, Biomedical Engineering Group, 555 Technology Square, Cambridge, MA 02139, USA
| | - José Luis Alonso
- Harvard Medical School, Massachusetts General Hospital, Division of Nephrology, 149 13th Street, Charlestown, MA 02129, USA
| | - Jeffrey T. Borenstein
- Charles Stark Draper Laboratory, Biomedical Engineering Group, 555 Technology Square, Cambridge, MA 02139, USA
| | - Xin Zhang
- Boston University, Department of Mechanical Engineering, 110 Cummington Street, Boston, MA 02215, USA
| | - M. Amin Arnaout
- Harvard Medical School, Massachusetts General Hospital, Division of Nephrology, 149 13th Street, Charlestown, MA 02129, USA
| | - Joseph L. Charest
- Charles Stark Draper Laboratory, Biomedical Engineering Group, 555 Technology Square, Cambridge, MA 02139, USA
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22
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Adair BD, Xiong JP, Alonso JL, Hyman BT, Arnaout MA. EM structure of the ectodomain of integrin CD11b/CD18 and localization of its ligand-binding site relative to the plasma membrane. PLoS One 2013; 8:e57951. [PMID: 23469114 PMCID: PMC3585415 DOI: 10.1371/journal.pone.0057951] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/27/2013] [Indexed: 11/19/2022] Open
Abstract
One-half of the integrin α-subunit Propeller domains contain and extra vWFA domain (αA domain), which mediates integrin binding to extracellular physiologic ligands via its metal-ion-dependent adhesion site (MIDAS). We used electron microscopy to determine the 3D structure of the αA-containing ectodomain of the leukocyte integrin CD11b/CD18 (αMβ2) in its inactive state. A well defined density for αA was observed within a bent ectodomain conformation, while the structure of the ectodomain in complex with the Fab fragment of mAb107, which binds at the MIDAS face of CD11b and stabilizes the inactive state, further revealed that αA is restricted to a relatively small range of orientations relative to the Propeller domain. Using Fab 107 as probe in fluorescent lifetime imaging microscopy (FLIM) revealed that αA is positioned relatively far from the membrane surface in the inactive state, and a systematic orientation search revealed that the MIDAS face would be accessible to extracellular ligand in the inactive state of the full-length cellular integrin. These studies are the first to define the 3D EM structure of an αA-containing integrin ectodomain and to position the ligand-binding face of αA domain in relation to the plasma membrane, providing new insights into current models of integrin activation.
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Affiliation(s)
- Brian D. Adair
- Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - Jian-Ping Xiong
- Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - José Luis Alonso
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - Bradley T. Hyman
- Division of Nephrology, and Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - M. Amin Arnaout
- Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
- Leukocyte Biology and Inflammation Program, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
- * E-mail:
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23
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Mahalingam B, Ajroud K, Alonso JL, Anand S, Adair B, Horenstein AL, Malavasi F, Xiong JP, Arnaout MA. Stable coordination of the inhibitory Ca2+ ion at the metal ion-dependent adhesion site in integrin CD11b/CD18 by an antibody-derived ligand aspartate: implications for integrin regulation and structure-based drug design. J Immunol 2011; 187:6393-401. [PMID: 22095715 PMCID: PMC3237904 DOI: 10.4049/jimmunol.1102394] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A central feature of integrin interaction with physiologic ligands is the monodentate binding of a ligand carboxylate to a Mg(2+) ion hexacoordinated at the metal ion-dependent adhesion site (MIDAS) in the integrin A domain. This interaction stabilizes the A domain in the high-affinity state, which is distinguished from the default low-affinity state by tertiary changes in the domain that culminate in cell adhesion. Small molecule ligand-mimetic integrin antagonists act as partial agonists, eliciting similar activating conformational changes in the A domain, which has contributed to paradoxical adhesion and increased patient mortality in large clinical trials. As with other ligand-mimetic integrin antagonists, the function-blocking mAb 107 binds MIDAS of integrin CD11b/CD18 A domain (CD11bA), but in contrast, it favors the inhibitory Ca(2+) ion over the Mg(2+) ion at MIDAS. We determined the crystal structures of the Fab fragment of mAb 107 complexed to the low- and high-affinity states of CD11bA. Favored binding of the Ca(2+) ion at MIDAS is caused by the unusual symmetric bidentate ligation of a Fab-derived ligand Asp to a heptacoordinated MIDAS Ca(2+) ion. Binding of the Fab fragment of mAb 107 to CD11bA did not trigger the activating tertiary changes in the domain or in the full-length integrin. These data show that the denticity of the ligand Asp/Glu can modify the divalent cation selectivity at MIDAS and hence integrin function. Stabilizing the Ca(2+) ion at MIDAS by bidentate ligation to a ligand Asp/Glu may provide one approach for designing pure integrin antagonists.
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Affiliation(s)
- Bhuvaneshwari Mahalingam
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Kaouther Ajroud
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Jose Luis Alonso
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Saurabh Anand
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Brian Adair
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Alberto L Horenstein
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Fabio Malavasi
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Jian-Ping Xiong
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - M. Amin Arnaout
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Address correspondence to: M. Amin Arnaout, Division of Nephrology, Massachusetts General Hospital, 149 13th Street, Charlestown, MA, 02129, Tel: 617-726-5663, Fax: 617-726-5671.
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24
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Levy BD, Zhang QY, Bonnans C, Primo V, Reilly JJ, Perkins DL, Liang Y, Amin Arnaout M, Nikolic B, Serhan CN. The endogenous pro-resolving mediators lipoxin A4 and resolvin E1 preserve organ function in allograft rejection. Prostaglandins Leukot Essent Fatty Acids 2011; 84:43-50. [PMID: 20869861 PMCID: PMC3019284 DOI: 10.1016/j.plefa.2010.09.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 09/06/2010] [Accepted: 09/07/2010] [Indexed: 12/31/2022]
Abstract
Allograft rejection remains a major limitation to successful solid organ transplantation. Here, we investigated the biosynthesis and bioactions of the pro-resolving mediators lipoxin A(4) and resolvin E1 in host responses to organ transplantation. In samples obtained during screening bronchoscopy after human lung transplantation, bronchoalveolar lavage fluid levels of lipoxin A(4) were increased in association with the severity of allograft rejection that was graded independently by clinical pathology. Lipoxin A(4) significantly inhibited calcineurin activation in human neutrophils, and lipoxin A(4) stable analogs prevented acute rejection of vascularized cardiac and renal allografts. Transgenic animals expressing human lipoxin A(4) receptors revealed important sites of action in host tissues for lipoxin A(4)'s protective effects. Resolvin E1 displays counter-regulatory actions for leukocytes, in part, via increased lipoxin A(4) biosynthesis, yet RvE1 administered (1μg, iv) to donor (days -1 and 0) and recipient mice (days -1, 0 and +4) was even more potent than a lipoxin stable analog (1μg, iv) in prolonging renal allograft survival (median survival time=74.0 days with RvE1 and 37.5 days with a LXA(4) analog). Together, these results highlight the potential for pro-resolving mediators in prolonging survival of solid organ transplants.
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Affiliation(s)
- Bruce D Levy
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Institutes of Medicine, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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25
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Primo VC, Marusic S, Franklin CC, Goldmann WH, Achaval CG, Smith RN, Arnaout MA, Nikolic B. Anti-PR3 immune responses induce segmental and necrotizing glomerulonephritis. Clin Exp Immunol 2009; 159:327-37. [PMID: 20015271 DOI: 10.1111/j.1365-2249.2009.04072.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Wegener's granulomatosis (WG) is a life-threatening autoimmune vasculitis that affects lungs, kidneys and other organs. A hallmark of WG is the presence of classic anti-neutrophil cytoplasmic antibodies (c-ANCA) against self-proteinase 3 (PR3). Little is known about the role of these antibodies and PR3-specific immune responses in disease development. In this study, we demonstrate that PR3-specific autoimmune responses are pathogenic in non-obese diabetic (NOD) mice with an impaired regulatory arm of the immune response. Immunization of autoimmunity prone NOD mice with rmPR3 (recombinant mouse PR3) in complete Freund's adjuvant (CFA) resulted in high levels of c-ANCA, without detectable disease development. However, when splenocytes from these immunized mice were transferred into immunodeficient NOD-severe combined immunodeficiency (SCID) mice, the recipient mice developed vasculitis and severe segmental and necrotizing glomerulonephritis. No disease developed in NOD-SCID mice that received splenocytes from the CFA-alone-immunized donors (controls), indicating that disease development depends upon PR3-specific immune responses. In contrast to the pathology observed in NOD-SCID mice, no disease was observed when splenocytes from rmPR3-immunized C57BL/6 mice were transferred into immunodeficient C57BL/6-RAG-1(-/-) mice, suggesting that complex and probably multi-genetic factors play a role in the regulation of disease development.
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Affiliation(s)
- V C Primo
- The Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
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26
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Xiong JP, Mahalingham B, Alonso JL, Borrelli LA, Rui X, Anand S, Hyman BT, Rysiok T, Müller-Pompalla D, Goodman SL, Arnaout MA. Crystal structure of the complete integrin alphaVbeta3 ectodomain plus an alpha/beta transmembrane fragment. J Cell Biol 2009; 186:589-600. [PMID: 19704023 PMCID: PMC2733745 DOI: 10.1083/jcb.200905085] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Accepted: 07/16/2009] [Indexed: 11/22/2022] Open
Abstract
We determined the crystal structure of 1TM-alphaVbeta3, which represents the complete unconstrained ectodomain plus short C-terminal transmembrane stretches of the alphaV and beta3 subunits. 1TM-alphaVbeta3 is more compact and less active in solution when compared with DeltaTM-alphaVbeta3, which lacks the short C-terminal stretches. The structure reveals a bent conformation and defines the alpha-beta interface between IE2 (EGF-like 2) and the thigh domains. Modifying this interface by site-directed mutagenesis leads to robust integrin activation. Fluorescent lifetime imaging microscopy of inactive full-length alphaVbeta3 on live cells yields a donor-membrane acceptor distance, which is consistent with the bent conformation and does not change in the activated integrin. These data are the first direct demonstration of conformational coupling of the integrin leg and head domains, identify the IE2-thigh interface as a critical steric barrier in integrin activation, and suggest that inside-out activation in intact cells may involve conformational changes other than the postulated switch to a genu-linear state.
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Affiliation(s)
- Jian-Ping Xiong
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Bhuvaneshwari Mahalingham
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Jose Luis Alonso
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Laura Ann Borrelli
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Xianliang Rui
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Saurabh Anand
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Bradley T. Hyman
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Thomas Rysiok
- Biologicals: Protein and Cell Science, Biologicals: Protein Purification, and Therapeutic Area Oncology: Biochemistry and Cellular Pharmacology, Merck-Serono Research, 64293 Darmstadt, Germany
| | - Dirk Müller-Pompalla
- Biologicals: Protein and Cell Science, Biologicals: Protein Purification, and Therapeutic Area Oncology: Biochemistry and Cellular Pharmacology, Merck-Serono Research, 64293 Darmstadt, Germany
| | - Simon L. Goodman
- Biologicals: Protein and Cell Science, Biologicals: Protein Purification, and Therapeutic Area Oncology: Biochemistry and Cellular Pharmacology, Merck-Serono Research, 64293 Darmstadt, Germany
| | - M. Amin Arnaout
- Program in Leukocyte Biology and Inflammation and Program in Structural Biology, Nephrology Division, Department of Medicine and Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
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27
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Gupta V, Alonso JL, Sugimori T, Essafi M, Issafi M, Xiong JP, Arnaout MA. Role of the beta-subunit arginine/lysine finger in integrin heterodimer formation and function. J Immunol 2008; 180:1713-8. [PMID: 18209068 DOI: 10.4049/jimmunol.180.3.1713] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Formation of the integrin alphabeta heterodimer is essential for cell surface expression and function. At the core of the alphabeta interface is a conserved Arg/Lys "finger" from the beta-subunit that inserts into a cup-like "cage" formed of two layers of aromatic residues in the alpha-subunit. We evaluated the role of this residue in heterodimer formation in an alphaA-lacking and an alphaA-containing integrin alphaVbeta3 and alphaMbeta2 (CD11b/CD18), respectively. Arg261 of beta3 was mutated to Ala or Glu; the corresponding Lys252 of beta2 was mutated to Ala, Arg, Glu, Asp, or Phe; and the effects on heterodimer formation in each integrin examined by ELISA and immunoprecipitation in HEK 293 cells cotransfected with plasmids encoding the alpha- and beta-subunits. The Arg261Glu (but not Arg261Ala) substitution significantly impaired cell surface expression and heterodimer formation of alphaVbeta3. Although Lys252Arg, and to a lesser extent Lys252Ala, were well tolerated, each of the remaining substitutions markedly reduced cell surface expression and heterodimer formation of CD11b/CD18. Lys252Arg and Lys252Ala integrin heterodimers displayed a significant increase in binding to the physiologic ligand iC3b. These data demonstrate an important role of the Arg/Lys finger in formation of a stable integrin heterodimer, and suggest that subtle changes at this residue affect the activation state of the integrin.
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Affiliation(s)
- Vineet Gupta
- Division of Nephrology, Leukocyte Biology and Inflammation Program, Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA
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28
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Arnaout MA, Goodman SL, Xiong JP. Structure and mechanics of integrin-based cell adhesion. Curr Opin Cell Biol 2007; 19:495-507. [PMID: 17928215 DOI: 10.1016/j.ceb.2007.08.002] [Citation(s) in RCA: 251] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 08/14/2007] [Indexed: 01/09/2023]
Abstract
Integrins are alpha/beta heterodimeric adhesion glycoprotein receptors that regulate a wide variety of dynamic cellular processes such as cell migration, phagocytosis, and growth and development. X-ray crystallography of the integrin ectodomain revealed its modular architecture and defined its metal-dependent interaction with extracellular ligands. This interaction is regulated from inside the cell (inside-out activation), through the short cytoplasmic alpha and beta integrin tails, which also mediate biochemical and mechanical signals transmitted to the cytoskeleton by the ligand-occupied integrins, effecting major changes in cell shape, behavior, and fate. Recent advances in the structural elucidation of integrins and integrin-binding cytoskeleton proteins are the subjects of this review.
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Affiliation(s)
- M Amin Arnaout
- Nephrology Division, Leukocyte Biology & Inflammation Program, Structural Biology Program, Massachusetts General Hospital, and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, United States.
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29
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Park JY, Arnaout MA, Gupta V. A simple, no-wash cell adhesion-based high-throughput assay for the discovery of small-molecule regulators of the integrin CD11b/CD18. J Biomol Screen 2007; 12:406-17. [PMID: 17438069 PMCID: PMC3075871 DOI: 10.1177/1087057106299162] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The leukocyte-specific integrin CD11b/CD18 plays a key role in the biological function of these cells and represents a validated therapeutic target for inflammatory diseases. Currently, the low affinity interaction between CD11b/CD18 integrin and its respective ligand poses a challenge in the development of cell-based adhesion assays for the high-throughput screening (HTS) environment. Here the authors describe a simple cell-based adhesion assay that can be readily used for HTS for the discovery of functional regulators of CD11b/CD18. The assay consistently produces acceptable Z' values (> 0.5) for HTS. After testing the assay using 2 established blocking antibodies as reference biologicals, the authors performed a proof-of-concept primary screen using a library of 6612 compounds and identified both agonist and antagonist hits.
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Affiliation(s)
- Jun Y Park
- Nephrology Division, Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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30
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Primo V, Zhang QY, Arnaout MA, Nikolic B. 151. Am J Kidney Dis 2007. [DOI: 10.1053/j.ajkd.2007.02.158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Optimal outpatient dialysis care is often difficult to achieve and a case management model to augment conventionally applied nursing and physician resources focusing on continuous quality improvement presents a possible solution to improving outcomes in this setting. We applied this model to patients followed by our physician group. Continuous quality improvement data generated from the dialysis unit database were used to analyze outcomes in patients enrolled in this model. Data from the cohort of patients followed in 2003 served as the reference source for comparative purposes. The nurse case manager assumed responsibility during the second quarter of 2004. Comparing outcomes data from 2005 with data from 2003, we were able to achieve a 3.12% improvement in the annualized mean percent crude mortality per 100 patient years (p<0.003). There was a 3.46-day trend to improvement in patient hospital days per year (p<0.06). The percentage of catheters used as primary access decreased by 9.59% (p<0.025), and the percentage of patients meeting an eKdrt/V goal > or =1.2 increased by 15.33% to 92.37% (p<0.001). These data appear to support the utility of a case manager model in our system.
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Affiliation(s)
- David J R Steele
- Nephrology Division, Department of Medicine, Massachusetts General Hospital (MGH), Boston, Massachusetts 02114, USA.
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32
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Abstract
Integrins are large modular cell-surface receptors that regulate almost every aspect of cellular function through bidirectional signals transmitted across the lipid bilayer. Regulation of integrin activity is accomplished by complex and still incompletely understood biochemical pathways that modify integrin ligand binding, clustering, trafficking, and signaling functions. The dynamic tertiary and quaternary changes required to channel some of these activities have hampered, until recently, the crystal structure determination of these heterodimeric receptors. In this chapter, we review the methods used to purify and characterize these proteins biophysically and functionally, and to derive their three-dimensional structures.
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Affiliation(s)
- Jian-Ping Xiong
- Structural Biology Program, Leukocyte Biology and Inflammation Program, Nephrology Division, Massachusetts General Hospital and Harvard Medical School, Charlestown, USA
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33
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Gupta V, Gylling A, Alonso JL, Sugimori T, Ianakiev P, Xiong JP, Arnaout MA. The beta-tail domain (betaTD) regulates physiologic ligand binding to integrin CD11b/CD18. Blood 2006; 109:3513-20. [PMID: 17170130 PMCID: PMC1852245 DOI: 10.1182/blood-2005-11-056689] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Crystallographic and electron microscopy studies revealed genuflexed (bent) integrins in both unliganded (inactive) and physiologic ligandbound (active) states, suggesting that local conformational changes are sufficient for activation. Herein we have explored the role of local changes in the contact region between the membrane-proximal beta-tail domain (betaTD) and the ligand-binding betaA domain of the bent conformation in regulating interaction of integrin CD11b/CD18 (alphaMbeta2) with its physiologic ligand iC3b. We replaced the betaTD CD loop residues D658GMD of the CD18 (beta2) subunit with the equivalent D672SSG of the beta3 subunit, with AGAA or with NGTD, expressed the respective heterodimeric receptors either transiently in epithelial HEK293T cells or stably in leukocytes (K562), and measured their ability to bind iC3b and to conformation-sensitive mAbs. In the presence of the physiologic divalent cations Ca(2+) plus Mg(2+) (at 1 mM each), the modified integrins showed increased (in HEK293) or constitutive (in K562) binding to iC3b compared with wild-type receptors. K562 expressing the betaTD-modified integrins bound in Ca(2+)Mg(2+) to the betaA-directed high-affinity reporter mAb 24 but not to mAb KIM127, a reporter of the genu-straightened state. These data identify a role for the membrane proximal betaTD as an allosteric modulator of integrin activation.
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Affiliation(s)
- Vineet Gupta
- Nephrology Division, Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA
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Zerria K, Jerbi E, Hammami S, Maaroufi A, Boubaker S, Xiong JP, Arnaout MA, Fathallah DM. Recombinant integrin CD11b A-domain blocks polymorphonuclear cells recruitment and protects against skeletal muscle inflammatory injury in the rat. Immunology 2006; 119:431-40. [PMID: 17026721 PMCID: PMC2265825 DOI: 10.1111/j.1365-2567.2006.02454.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The beta2 integrin CD11b/CD18 (CR3) is a major adhesion receptor of neutrophils, normally utilized to fend off infections. This receptor contributes, however, to multiple forms of non-infectious inflammatory injury when dysregulated as shown in gene knock-outs and through the use of blocking monoclonal antibodies. The major ligand recognition site of CR3 has been mapped to the A-domain in the CD11b subunit (CD11bA). The recombinant form of this domain exhibits a ligand binding profile similar to that of the holoreceptor. To assess the potential anti-inflammatory activity of CD11bA as a competitive antagonist of CR3 in vivo, we assessed its effects on a developed animal model of traumatic skeletal muscle injury in the rat. Recombinant soluble rat CD11bA-domain fused to glutathione-S-transferase (GST) was administered intravenously in a single dose at 1 mg/kg to nine groups of Wistar rats, five in each group, 30 min before inducing traumatic skeletal muscle injury. Control animals received either a function-blocking anti-CD11b/CD18 monoclonal antibody (1 mg/kg), non-functional mutant forms of the CD11bA (D140GS/AGA, T209/A, D242/A), recombinant GST or buffer alone. In control animals, the wounded muscle showed oedema, erythrocyte extravasation and myonecrosis both within and outside the immediate wounded area (5-10 mm zone) and influx of neutrophils was detected 30 min post-wound, followed by a second wave 3 hr later. Wild-type CD11bA- or anti-CD11b monoclonal antibody (mAb)-treated rats showed a comparable and significant decrease in the number of infiltrating PMN (78 + 4%, n = 70 and 86 +/- 2%, n = 50, respectively) and preservation of the muscular fibres outside the immediate zone of necrosis (75 + 4%, n = 70, 84 +/- 1%, n = 50, respectively), compared to controls. These data demonstrate that CD11bA can be an effective tissue-preserving agent in acute inflammatory muscular injury.
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MESH Headings
- Amino Acid Sequence
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/immunology
- Anti-Inflammatory Agents, Non-Steroidal/therapeutic use
- Antibodies, Monoclonal/immunology
- CD11b Antigen/immunology
- CD11b Antigen/therapeutic use
- Disease Models, Animal
- Female
- Molecular Sequence Data
- Muscle Fibers, Skeletal/immunology
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/immunology
- Muscle, Skeletal/injuries
- Muscle, Skeletal/pathology
- Myositis/immunology
- Myositis/prevention & control
- Neutrophil Infiltration/immunology
- Rats
- Rats, Wistar
- Recombinant Proteins/therapeutic use
- Sequence Alignment
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Affiliation(s)
- K Zerria
- Molecular Biotechnology Group, Institute Pasteur, Tunis, Tunisia
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35
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Li X, Xiong JW, Shelley CS, Park H, Arnaout MA. The transcription factor ZBP-89 controls generation of the hematopoietic lineage in zebrafish and mouse embryonic stem cells. Development 2006; 133:3641-50. [PMID: 16914492 DOI: 10.1242/dev.02540] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Hematopoietic development is closely linked to that of blood vessels and the two processes are regulated in large part by transcription factors that control cell fate decisions and cellular differentiation. Both blood and blood vessels derive from a common progenitor, termed the hemangioblast, but the factor(s) specifying the development and differentiation of this stem cell population into the hematopoietic and vascular lineages remain ill defined. Here, we report that knockdown of the Krüppel-like transcription factor ZBP-89 in zebrafish embryos results in a bloodless phenotype, caused by disruption of both primitive and definitive hematopoiesis, while leaving primary blood vessel formation intact. Injection of ZBP-89 mRNA into cloche zebrafish embryos, which lack both the hematopoietic and endothelial lineages, rescues hematopoiesis but not vasculogenesis. Injection of mRNA for Stem Cell Leukemia (SCL), a transcription factor that directs hemangioblast development into blood cell precursors, rescues the bloodless phenotype in ZBP-89 zebrafish morphants. Forced expression of ZBP-89 induces the expansion of hematopoietic progenitors in wild-type zebrafish and in mouse embryonic stem cell cultures but inhibits angiogenesis in vivo and in vitro. These findings establish a unique regulatory role for ZBP-89, positioned at the interface between early blood and blood vessel development.
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Affiliation(s)
- Xiangen Li
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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36
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Ding Z, Bradley KA, Amin Arnaout M, Xiong JP. Expression and purification of functional human anthrax toxin receptor (ATR/TEM8) binding domain from Escherichia coli. Protein Expr Purif 2006; 49:121-8. [PMID: 16798009 DOI: 10.1016/j.pep.2006.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 04/18/2006] [Accepted: 04/23/2006] [Indexed: 10/24/2022]
Abstract
Anthrax is caused by the gram-positive, spore-forming bacterium, Bacillus anthracis. Anthrax receptors play a crucial role in the pathogenesis of the anthrax disease. Anthrax toxin receptor ATR/TEM8 VWA domain is responsible for the binding of protective antigen (PA) of B. anthracis, and thus an attractive target for structure-based drug therapies. However, the production of soluble and functional ATR/TEM8 VWA domain currently requires the use of mammalian expression systems. In this work, we expressed the ATR/TEM8 VWA domain as a fusion protein in Escherichia coli. Recombinant ATR/TEM8 VWA domain has been purified to homogeneity, and its identity has been verified by both N-terminal protein microsequencing and mass spectrometry. The purified ATR/TEM8 VWA domain exhibits very high affinity to PA based on BIAcore assay. Moreover, like the domain expressed in mammalian system, the bacterially expressed ATR/TEM8 VWA domain can block cytotoxicity induced by anthrax toxins, suggesting that the bacterially expressed ATR/TEM8 VWA domain is properly folded and fully functional.
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Affiliation(s)
- Zhiping Ding
- Leukocyte Biology and Inflammation Program, Renal Unit, Nephrology Division, Massachusetts General Hospital, Harvard Medical School, 149 13th street, Charlestown, MA 02129, USA
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37
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Abstract
Alphabeta heterodimeric integrins mediate dynamic adhesive cell-cell and cell-extracellular matrix (ECM) interactions in metazoa that are critical in growth and development, hemostasis, and host defense. A central feature of these receptors is their capacity to change rapidly and reversibly their adhesive functions by modulating their ligand-binding affinity. This is normally achieved through interactions of the short cytoplasmic integrin tails with intracellular proteins, which trigger restructuring of the ligand-binding site through long-range conformational changes in the ectodomain. Ligand binding in turn elicits conformational changes that are transmitted back to the cell to regulate diverse responses. The publication of the integrin alphaVbeta3 crystal structure has provided the context for interpreting decades-old biochemical studies. Newer NMR, crystallographic, and EM data, reviewed here, are providing a better picture of the dynamic integrin structure and the allosteric changes that guide its diverse functions.
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Affiliation(s)
- M A Arnaout
- Structural Biology Program, Leukocyte Biology and Inflammation Program, Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachussetts 02129, USA.
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38
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Devchand PR, Schmidt BA, Primo VC, Zhang QY, Arnaout MA, Serhan CN, Nikolic B. A synthetic eicosanoid LX-mimetic unravels host-donor interactions in allogeneic BMT-induced GvHD to reveal an early protective role for host neutrophils. FASEB J 2005; 19:203-10. [PMID: 15677343 DOI: 10.1096/fj.04-2565com] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Lipoxin A(4) (LXA(4)) and aspirin-triggered 15-epi-LXA(4) are potent endogenous lipid mediators thought to define the inflammatory set-point. We used single prophylactic administrations of a synthetic aspirin-triggered lipoxin A(4) signal mimetic, ATLa, to probe dynamics of early host-donor interactions in a mouse model for the inflammation-associated multifactorial disease of allogeneic bone marrow transplant (BMT) -induced graft-vs.-host disease (GvHD). We first demonstrated that both host and donor are responsive to the ATLa signals. The simple and restricted regimen of a single prophylactic administration of ATLa [100 ng/mL to donor cells or 1 microg (approximately 50 microg/kg) i.v. to host] was sufficient to delay death. Clinical indicators of weight, skin lesions, diarrhea and eye inflammation were monitored. Histological analyses on day 45 post-BMT showed that the degree of cellular trafficking, particularly neutrophil infiltrate, and protection of end-organ target pathology are different, depending on whether the host or donor was treated with ATLa. Taken together, these results chart some ATLa protective effects on GvHD cellular dynamics over time and identify a previously unrecognized effect of host neutrophils in the early phase post-BMT as important determinants in the dynamics of GvHD onset and progression.-Devchand, P. R., Schmidt, B. A., Primo, V. C., Zhang, Q.-y., Arnaout, M. A., Serhan, C. N., Nikolic, B. A synthetic eicosanoid LX-mimetic unravels host-donor interactions in allogeneic BMT-induced GvHD to reveal an early protective role for host neutrophils.
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Affiliation(s)
- Pallavi R Devchand
- Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston 02115, USA
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Adair BD, Xiong JP, Maddock C, Goodman SL, Arnaout MA, Yeager M. Three-dimensional EM structure of the ectodomain of integrin {alpha}V{beta}3 in a complex with fibronectin. ACTA ACUST UNITED AC 2005; 168:1109-18. [PMID: 15795319 PMCID: PMC2171847 DOI: 10.1083/jcb.200410068] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Integrins are αβ heterodimeric cell surface receptors that mediate transmembrane signaling by binding extracellular and cytoplasmic ligands. The ectodomain of integrin αVβ3 crystallizes in a bent, genuflexed conformation considered to be inactive (unable to bind physiological ligands in solution) unless it is fully extended by activating stimuli. We generated a stable, soluble complex of the Mn2+-bound αVβ3 ectodomain with a fragment of fibronectin (FN) containing type III domains 7 to 10 and the EDB domain (FN7-EDB-10). Transmission electron microscopy and single particle image analysis were used to determine the three-dimensional structure of this complex. Most αVβ3 particles, whether unliganded or FN-bound, displayed compact, triangular shapes. A difference map comparing ligand-free and FN-bound αVβ3 revealed density that could accommodate the RGD-containing FN10 in proximity to the ligand-binding site of β3, with FN9 just adjacent to the synergy site binding region of αV. We conclude that the ectodomain of αVβ3 manifests a bent conformation that is capable of stably binding a physiological ligand in solution.
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Affiliation(s)
- Brian D Adair
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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40
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Abstract
Integrin beta-subunits contain an N-terminal PSI (for plexin-semaphorin-integrin) domain that contributes to integrin activation and harbors the PI(A) alloantigen associated with immune thrombocytopenias and susceptibility to sudden cardiac death. Here we report the crystal structure of PSI in the context of the crystallized alphaVbeta3 ectodomain. The integrin PSI forms a two-stranded antiparallel beta-sheet flanked by two short helices; its long interstrand loop houses Pl(A) and may face the EGF2 domain. The integrin PSI contains four cysteine pairs connected in a 1-4, 2-8, 3-6, 5-7 pattern. An unexpected feature of the structure is that the final, eighth cysteine is located C-terminal to the Ig-like hybrid domain and is thus separated by the hybrid domain from the other seven cysteines of PSI. This architecture may be relevant to the evolution of integrins and should help refine the current models of integrin activation.
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Affiliation(s)
- Jian-Ping Xiong
- Structural Biology Program, Leukocyte Biology and Inflammation Program, Renal Unit
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41
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Ajroud K, Sugimori T, Goldmann WH, Fathallah DM, Xiong JP, Arnaout MA. Binding Affinity of Metal Ions to the CD11b A-domain Is Regulated by Integrin Activation and Ligands. J Biol Chem 2004; 279:25483-8. [PMID: 15070893 DOI: 10.1074/jbc.m402901200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The divalent cations Mg(2+) and Ca(2+) regulate the interaction of integrins with their cognate ligands, with Mg(2+) uniformly facilitating and Ca(2+) generally inhibiting such interactions in vitro. Because both cations are present in mm concentrations in vivo, the physiologic relevance of the in vitro observations is unclear. We measured the affinity of both cations to the inactive and active states of the ligand- and cation-binding A-domain (CD11bA) from integrin CD11b/CD18 in the absence and presence of the single-chain 107 antibody (scFv107), an activation-insensitive ligand-mimetic antibody. Using titration calorimetry, we found that Mg(2+) and Ca(2+) display equivalent (mm) affinities to inactive CD11bA. Activation induced a approximately 10-fold increase in the binding affinity of Mg(2+) to CD11bA with no change in that of Ca(2+) (106 microm +/- 16 and 2.1 mm +/- 0.19, respectively, n = 4). This increase is largely driven by favorable enthalpy. scFv107 induced a 50-80-fold increase in the binding affinity of Ca(2+) (but not Mg(2+) or Mn(2+)) to either form of CD11bA. Thus the affinity of metal ions to integrins is itself regulated by the activation state of these receptors and by certain ligands. These findings, which we expect will be applicable in vivo, elucidate a new level of regulation of the integrin-metal-ligand ternary complex and help explain some of the discrepant effects of Ca(2+) on integrin-ligand interactions.
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Affiliation(s)
- Kaouther Ajroud
- Leukocyte Biology and Inflammation Program, Renal Unit, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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42
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43
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Arnaout MA. Integrin structure: new twists and turns in dynamic cell adhesion. Immunol Rev 2003. [DOI: 10.1046/j.0019-2805.2001.01368.x-i1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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44
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Abstract
Integrins are cell adhesion receptors that communicate biochemical and mechanical signals in a bidirectional manner across the plasma membrane and thus influence most cellular functions. Intracellular signals switch integrins into a ligand-competent state as a result of elicited conformational changes in the integrin ectodomain. Binding of extracellular ligands induces, in turn, structural changes that convey distinct signals to the cell interior. The structural basis of this bidirectional signaling has been the focus of intensive study for the past 3 decades. In this perspective, we develop a new hypothesis for integrin activation based on recent crystallographic, electron microscopic, and biochemical studies.
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Affiliation(s)
- Jian-Ping Xiong
- Renal Unit, Leukocyte Biology and Inflammation Program, Structural Biology Program, Massachusetts General Hospital, and Harvard Medical School, Charlestown, MA 02129, USA
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45
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Abstract
Integrins are cell adhesion receptors that couple extracellular divalent cation-dependent recognition events with intracellular mechanical and biochemical responses and vice versa, thus affecting every function of nucleated cells. The structural basis of this bidirectional signaling and its dependency on cations has been the focus of intensive study over the past three decades. Significant progress made recently in elucidating the three-dimensional structure of the extracellular and cytoplasmic segments of integrins is giving valuable new insights into the tertiary and quaternary changes that underlie activation, ligand recognition and signaling by these receptors.
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Affiliation(s)
- J-P Xiong
- Renal Unit, Leukocyte Biology & Inflammation Program, Structural Biology Program, Massachusetts General Hospital, Charlestown, MA 02129, USA
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46
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Nicolaou F, Teodoridis JM, Park H, Georgakis A, Farokhzad OC, Böttinger EP, Da Silva N, Rousselot P, Chomienne C, Ferenczi K, Arnaout MA, Shelley CS. CD11c gene expression in hairy cell leukemia is dependent upon activation of the proto-oncogenes ras and junD. Blood 2003; 101:4033-41. [PMID: 12576324 DOI: 10.1182/blood-2002-01-0324] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hairy cell leukemia (HCL) is a chronic lymphoproliferative disease, the cause of which is unknown. Diagnostic of HCL is abnormal expression of the gene that encodes the beta2 integrin CD11c. In order to determine the cause of CD11c gene expression in HCL the CD11c gene promoter was characterized. Transfection of the CD11c promoter linked to a luciferase reporter gene indicated that it is sufficient to direct expression in hairy cells. Mutation analysis demonstrated that of predominant importance to the activity of the CD11c promoter is its interaction with the activator protein-1 (AP-1) family of transcription factors. Comparison of nuclear extracts prepared from hairy cells with those prepared from other cell types indicated that hairy cells exhibit abnormal constitutive expression of an AP-1 complex containing JunD. Functional inhibition of AP-1 expressed by hairy cells reduced CD11c promoter activity by 80%. Inhibition of Ras, which represents an upstream activator of AP-1, also significantly inhibited the CD11c promoter. Furthermore, in the hairy cell line EH, inhibition of Ras signaling through mitogen-activated protein kinase/extracellular signal-regulated kinase kinases 1 and 2 (MEK1/2) reduced not only CD11c promoter activity but also reduced both CD11c surface expression and proliferation. Expression in nonhairy cells of a dominant-positive Ras mutant activated the CD11c promoter to levels equivalent to those in hairy cells. Together, these data indicate that the abnormal expression of the CD11c gene characteristic of HCL is dependent upon activation of the proto-oncogenes ras and junD.
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Affiliation(s)
- Fotini Nicolaou
- Renal Unit, Massachusetts General Hospital, Charlestown, MA 02129, USA
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47
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Abstract
Integrin CD11b is a differentiation marker of the myelomonocytic lineage and an important mediator of inflammation. Expression of the CD11b gene is transcriptionally induced as myeloid precursors differentiate into mature cells, then drops as monocytes further differentiate into macrophages. Previous studies have identified elements and factors involved in the transcriptional activation of the CD11b gene during myeloid differentiation, but no data exist regarding potential down-regulatory factors, especially in the later stages of differentiation. Using 2 copies of a GC-rich element (-141 to -110) in the CD11b promoter, we probed a cDNA expression library for interacting proteins. Three clones were identified among 9.1 million screened, all encoding the DNA-binding domain of the zinc finger factor ZBP-89. Overexpression of ZBP-89 in the monocyte precursor cell line U937 reduced CD11b promoter-driven luciferase activity when U937 cells were induced to differentiate into monocytelike cells using phorbol esters. To identify the differentiation stage at which ZBP-89 repression of the CD11b gene is exerted, the protein level of ZBP-89 was correlated with that of CD11b mRNA in differentiating U937 as well as in normal human monocytes undergoing in vitro differentiation into macrophages. A clear inverse relationship was observed in the latter but not the former state, suggesting that ZBP-89 represses CD11b gene expression during the further differentiation of monocytes into macrophages.
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Affiliation(s)
- Heiyoung Park
- Leukocyte Biology and Inflammation Program, Renal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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48
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Xu GM, González-Perrett S, Essafi M, Timpanaro GA, Montalbetti N, Arnaout MA, Cantiello HF. Polycystin-1 activates and stabilizes the polycystin-2 channel. J Biol Chem 2003; 278:1457-62. [PMID: 12407099 DOI: 10.1074/jbc.m209996200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is a prevalent genetic disorder largely caused by mutations in the PKD1 and PKD2 genes that encode the transmembrane proteins polycystin-1 and -2, respectively. Both proteins appear to be involved in the regulation of cell growth and maturation, but the precise mechanisms are not yet well defined. Polycystin-2 has recently been shown to function as a Ca(2+)-permeable, non-selective cation channel. Polycystin-2 interacts through its cytoplasmic carboxyl-terminal region with a coiled-coil motif in the cytoplasmic tail of polycystin-1 (P1CC). The functional consequences of this interaction on its channel activity, however, are unknown. In this report, we show that P1CC enhanced the channel activity of polycystin-2. R742X, a disease-causing polycystin-2 mutant lacking the polycystin-1 interacting region, fails to respond to P1CC. Also, P1CC containing a disease-causing mutation in its coiled-coil motif loses its stimulatory effect on wild-type polycystin-2 channel activity. The modulation of polycystin-2 channel activity by polycystin-1 may be important for the various biological processes mediated by this molecular complex.
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Affiliation(s)
- G Mark Xu
- Renal Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachussetts 02129, USA
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49
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Abstract
Integrins are alphabeta heterodimeric cell-surface receptors that are vital to the survival and function of nucleated cells. They recognize aspartic-acid- or a glutamic-acid-based sequence motifs in structurally diverse ligands. Integrin recognition of most ligands is divalent cation dependent and conformationally sensitive. In addition to this common property, there is an underlying binding specificity between integrins and ligands for which there has been no structural basis. The recently reported crystal structures of the extracellular segment of an integrin in its unliganded state and in complex with a prototypical Arg-Gly-Asp (RGD) ligand have provided an atomic basis for cation-mediated binding of aspartic-acid-based ligands to integrins. They also serve as a basis for modelling other integrins in complex with larger physiologic ligands. These models provide new insights into the molecular basis for ligand binding specificity in integrins and its regulation by activation-driven tertiary and quaternary changes.
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Affiliation(s)
- M Amin Arnaout
- Renal Unit, Leukocyte Biology and Inflammation Program, Massachusetts General Hospital, and Harvard Medical School, Charlestown, MA 02129, USA.
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50
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Seow KT, Xiong JP, Arnaout MA, Welge J, Rippmann F, Goodman SL. Divalent cations and the relationship between alphaA and betaA domains in integrins. Biochem Pharmacol 2002; 64:805-12. [PMID: 12213573 DOI: 10.1016/s0006-2952(02)01142-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Integrins contain either one or two von Willebrand factor A-like domains, which are primary ligand and cation binding regions in the molecules. Here we examine the first structure of an A domain of a beta subunit, in alphanubeta3 and compare it to known A domain structures of alpha subunits. Ligand binding to immobilized alphanubeta3 domain is stimulated by Ca2+ rather than inhibited by it. Biochemical, cell biological and structural evidence suggests that the A domain is a major site of ligand interaction in alphanubeta3. The Arg-Gly-Asp based inhibitor cilengitide (EMD 121974) inhibites ligand interaction with transmembrane-truncated alphanubeta3 in the presence of either Ca2+ or Mn2+ ions, and does so with similar kinetics. The alphanubeta3 structure reveals that both the alphaA and betaA domains share common structural cores. But, in contrast to alphaA, the betaA domain has three cation binding sites, that are involved either directly or indirectly in ligand binding. Structural alignment of alphaA and betaA domains reveals additional loops unique only to the betaA domain and much evidence support that that these loops are important for ligand binding specificity and for the interaction between alpha and beta subunits. Since the position of these loops are evolutionary conserved but their primary sequence varies between the various betaA domains, they represents potential targets for dissecting functional diversity among integrins.
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Affiliation(s)
- Kah-Tong Seow
- Department of Bio- and Chemoinformatics, Merck KGaA, Frankfurterstr. 250, Darmstadt, Germany
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