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Burgos-Bravo F, Figueroa NL, Casanova-Morales N, Quest AFG, Wilson CAM, Leyton L. Single-molecule measurements of the effect of force on Thy-1/αvβ3-integrin interaction using nonpurified proteins. Mol Biol Cell 2017; 29:326-338. [PMID: 29212879 PMCID: PMC5996956 DOI: 10.1091/mbc.e17-03-0133] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 10/10/2017] [Accepted: 12/01/2017] [Indexed: 12/11/2022] Open
Abstract
Single-molecule measurements combined with a novel mathematical strategy were applied to accurately characterize how bimolecular interactions respond to mechanical force, especially when protein purification is not possible. Specifically, we studied the effect of force on Thy-1/αvβ3 integrin interaction, a mediator of neuron-astrocyte communication. Thy-1 and αvβ3 integrin mediate bidirectional cell-to-cell communication between neurons and astrocytes. Thy-1/αvβ3 interactions stimulate astrocyte migration and the retraction of neuronal prolongations, both processes in which internal forces are generated affecting the bimolecular interactions that maintain cell–cell adhesion. Nonetheless, how the Thy-1/αvβ3 interactions respond to mechanical cues is an unresolved issue. In this study, optical tweezers were used as a single-molecule force transducer, and the Dudko-Hummer-Szabo model was applied to calculate the kinetic parameters of Thy-1/αvβ3 dissociation. A novel experimental strategy was implemented to analyze the interaction of Thy-1-Fc with nonpurified αvβ3-Fc integrin, whereby nonspecific rupture events were corrected by using a new mathematical approach. This methodology permitted accurately estimating specific rupture forces for Thy-1-Fc/αvβ3-Fc dissociation and calculating the kinetic and transition state parameters. Force exponentially accelerated Thy-1/αvβ3 dissociation, indicating slip bond behavior. Importantly, nonspecific interactions were detected even for purified proteins, highlighting the importance of correcting for such interactions. In conclusion, we describe a new strategy to characterize the response of bimolecular interactions to forces even in the presence of nonspecific binding events. By defining how force regulates Thy-1/αvβ3 integrin binding, we provide an initial step towards understanding how the neuron–astrocyte pair senses and responds to mechanical cues.
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Affiliation(s)
- Francesca Burgos-Bravo
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
| | - Nataniel L Figueroa
- Physics Department, Pontificia Universidad Católica de Chile, 782-0436 Santiago, Chile
| | - Nathalie Casanova-Morales
- Biochemistry and Molecular Biology Department, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 838-0494 Santiago, Chile
| | - Andrew F G Quest
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
| | - Christian A M Wilson
- Biochemistry and Molecular Biology Department, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 838-0494 Santiago, Chile
| | - Lisette Leyton
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile .,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
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Kononova O, Litvinov RI, Blokhin DS, Klochkov VV, Weisel JW, Bennett JS, Barsegov V. Mechanistic Basis for the Binding of RGD- and AGDV-Peptides to the Platelet Integrin αIIbβ3. Biochemistry 2017; 56:1932-1942. [PMID: 28277676 DOI: 10.1021/acs.biochem.6b01113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Binding of soluble fibrinogen to the activated conformation of the integrin αIIbβ3 is required for platelet aggregation and is mediated exclusively by the C-terminal AGDV-containing dodecapeptide (γC-12) sequence of the fibrinogen γ chain. However, peptides containing the Arg-Gly-Asp (RGD) sequences located in two places in the fibrinogen Aα chain inhibit soluble fibrinogen binding to αIIbβ3 and make substantial contributions to αIIbβ3 binding when fibrinogen is immobilized and when it is converted to fibrin. Here, we employed optical trap-based nanomechanical measurements and computational molecular modeling to determine the kinetics, energetics, and structural details of cyclic RGDFK (cRGDFK) and γC-12 binding to αIIbβ3. Docking analysis revealed that NMR-determined solution structures of cRGDFK and γC-12 bind to both the open and closed αIIbβ3 conformers at the interface between the αIIb β-propeller domain and the β3 βI domain. The nanomechanical measurements revealed that cRGDFK binds to αIIbβ3 at least as tightly as γC-12. A subsequent analysis of molecular force profiles and the number of peptide-αIIbβ3 binding contacts revealed that both peptides form stable bimolecular complexes with αIIbβ3 that dissociate in the 60-120 pN range. The Gibbs free energy profiles of the αIIbβ3-peptide complexes revealed that the overall stability of the αIIbβ3-cRGDFK complex was comparable with that of the αIIbβ3-γC-12 complex. Thus, these results provide a mechanistic explanation for previous observations that RGD- and AGDV-containing peptides are both potent inhibitors of the αIIbβ3-fibrinogen interactions and are consistent with the observation that RGD motifs, in addition to AGDV, support interaction of αIIbβ3 with immobilized fibrinogen and fibrin.
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Affiliation(s)
- Olga Kononova
- Department of Chemistry, University of Massachusetts , Lowell, Massachusetts 01854, United States.,Moscow Institute of Physics and Technology , Moscow Region 141700, Russian Federation
| | | | | | | | | | | | - Valeri Barsegov
- Department of Chemistry, University of Massachusetts , Lowell, Massachusetts 01854, United States.,Moscow Institute of Physics and Technology , Moscow Region 141700, Russian Federation
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Dutta S, Armitage BA, Lyubchenko YL. Probing of miniPEGγ-PNA-DNA Hybrid Duplex Stability with AFM Force Spectroscopy. Biochemistry 2016; 55:1523-8. [PMID: 26898903 DOI: 10.1021/acs.biochem.5b01250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide nucleic acids (PNA) are synthetic polymers, the neutral peptide backbone of which provides elevated stability to PNA-PNA and PNA-DNA hybrid duplexes. It was demonstrated that incorporation of diethylene glycol (miniPEG) at the γ position of the peptide backbone increased the thermal stability of the hybrid duplexes (Sahu, B. et al. J. Org. Chem. 2011, 76, 5614-5627). Here, we applied atomic force microscopy (AFM) based single molecule force spectroscopy and dynamic force spectroscopy (DFS) to test the strength and stability of the hybrid 10 bp duplex. This hybrid duplex consisted of miniPEGγ-PNA and DNA of the same length (γ(MP)PNA-DNA), which we compared to a DNA duplex with a homologous sequence. AFM force spectroscopy data obtained at the same conditions showed that the γ(MP)PNA-DNA hybrid is more stable than the DNA counterpart, 65 ± 15 pN vs 47 ± 15 pN, respectively. The DFS measurements performed in a range of pulling speeds analyzed in the framework of the Bell-Evans approach yielded a dissociation constant, koff ≈ 0.030 ± 0.01 s⁻¹ for γ(MP)PNA-DNA hybrid duplex vs 0.375 ± 0.18 s⁻¹ for the DNA-DNA duplex suggesting that the hybrid duplex is much more stable. Correlating the high affinity of γ(MP)PNA-DNA to slow dissociation kinetics is consistent with prior bulk characterization by surface plasmon resonance. Given the growing interest in γ(MP)PNA as well as other synthetic DNA analogues, the use of single molecule experiments along with computational analysis of force spectroscopy data will provide direct characterization of various modifications as well as higher order structures such as triplexes and quadruplexes.
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Affiliation(s)
- Samrat Dutta
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , Omaha, Nebraska, United States
| | - Bruce A Armitage
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University , Pittsburgh, Pennsylvania, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , Omaha, Nebraska, United States
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Pandya DN, Hantgan R, Budzevich MM, Kock ND, Morse DL, Batista I, Mintz A, Li KC, Wadas TJ. Preliminary Therapy Evaluation of (225)Ac-DOTA-c(RGDyK) Demonstrates that Cerenkov Radiation Derived from (225)Ac Daughter Decay Can Be Detected by Optical Imaging for In Vivo Tumor Visualization. Theranostics 2016; 6:698-709. [PMID: 27022417 PMCID: PMC4805664 DOI: 10.7150/thno.14338] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 01/09/2016] [Indexed: 12/12/2022] Open
Abstract
The theranostic potential of 225Ac-based radiopharmaceuticals continues to increase as researchers seek innovative ways to harness the nuclear decay of this radioisotope for therapeutic and imaging applications. This communication describes the evaluation of 225Ac-DOTA-c(RGDyK) in both biodistribution and Cerenkov luminescence imaging (CLI) studies. Initially, La-DOTA-c(RGDyK) was prepared as a non-radioactive surrogate to evaluate methodologies that would contribute to an optimized radiochemical synthetic strategy and estimate the radioactive conjugate's affinity for αvβ3, using surface plasmon resonance spectroscopy. Surface plasmon resonance spectroscopy studies revealed the IC50 and Ki of La-DOTA-c(RGDyK) to be 33 ± 13 nM and 26 ± 11 nM, respectively, and suggest that the complexation of the La3+ ion to the conjugate did not significantly alter integrin binding. Furthermore, use of this surrogate allowed optimization of radiochemical synthesis strategies to prepare 225Ac-DOTA-c(RGDyK) with high radiochemical purity and specific activity similar to other 225Ac-based radiopharmaceuticals. This radiopharmaceutical was highly stable in vitro. In vivo biodistribution studies confirmed the radiotracer's ability to target αvβ3 integrin with specificity; specificity was detected in tumor-bearing animals using Cerenkov luminescence imaging. Furthermore, tumor growth control was achieved using non-toxic doses of the radiopharmaceutical in U87mg tumor-bearing nude mice. To our knowledge, this is the first report to describe the CLI of αvβ3+ tumors in live animals using the daughter products derived from 225Ac decay in situ. This concept holds promise to further enhance development of targeted alpha particle therapy.
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