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Gressett TE, Nader D, Robles JP, Buranda T, Kerrigan SW, Bix G. Integrins as Therapeutic Targets for SARS-CoV-2. Front Cell Infect Microbiol 2022; 12:892323. [PMID: 35619646 PMCID: PMC9128570 DOI: 10.3389/fcimb.2022.892323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/11/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Timothy E. Gressett
- Tulane University School of Medicine, Clinical Neuroscience Research Center (CNRC), New Orleans, LA, United States
- Department of Neurology, Tulane University School of Medicine, New Orleans, LA, United States
- Tulane Brain Institute, Tulane University, New Orleans, LA, United States
| | - Danielle Nader
- RCSI University of Medicine and Health Sciences, School of Pharmacy and Biomolecular Sciences (PBS), Dublin, Ireland
| | - Juan Pablo Robles
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Juriquilla, Mexico
| | - Tione Buranda
- University of New Mexico Health Sciences Center (HSC), Department of Pathology, Albuquerque, NM, United States
| | - Steven W. Kerrigan
- RCSI University of Medicine and Health Sciences, School of Pharmacy and Biomolecular Sciences (PBS), Dublin, Ireland
| | - Gregory Bix
- Tulane University School of Medicine, Clinical Neuroscience Research Center (CNRC), New Orleans, LA, United States
- Department of Neurology, Tulane University School of Medicine, New Orleans, LA, United States
- Tulane Brain Institute, Tulane University, New Orleans, LA, United States
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2
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Simons P, Rinaldi DA, Bondu V, Kell AM, Bradfute S, Lidke DS, Buranda T. Integrin activation is an essential component of SARS-CoV-2 infection. Sci Rep 2021; 11:20398. [PMID: 34650161 PMCID: PMC8516859 DOI: 10.1038/s41598-021-99893-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [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: 07/23/2021] [Accepted: 09/30/2021] [Indexed: 02/07/2023] Open
Abstract
SARS-CoV-2 infection depends on binding its spike (S) protein to angiotensin-converting enzyme 2 (ACE2). The S protein expresses an RGD motif, suggesting that integrins may be co-receptors. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating cell entry and productive infection. We used flow cytometry and confocal microscopy to show that SARS-CoV-2R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn2+, which induces integrin extension, enhances cell entry of SARS-CoV-2R18. We also show that one class of integrin antagonist, which binds to the αI MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2R18 with basal state integrins, but is ineffective against Mn2+-activated integrins. RGD-integrin antagonists inhibited SARS-CoV-2R18 binding regardless of integrin activation status. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand-binding function of integrins via a talin-dependent mechanism, and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by Gα13. Using cell-permeable peptide inhibitors of talin and Gα13 binding to the cytoplasmic tail of an integrin's β subunit, we demonstrate that talin-mediated signaling is essential for productive infection.
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Affiliation(s)
- Peter Simons
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Derek A Rinaldi
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Virginie Bondu
- Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Alison M Kell
- Molecular Genetics and Microbiology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.,Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Steven Bradfute
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.,Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Diane S Lidke
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.,Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA
| | - Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA. .,Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA.
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Simons P, Guo Y, Bondu V, Tigert SL, Harkins M, Goodfellow S, Tompkins C, Chabot-Richards D, Yang XO, Bosc LG, Bradfute S, Lawrence DA, Buranda T. Longitudinal Assessment of Cytokine Expression and Plasminogen Activation in Hantavirus Cardiopulmonary Syndrome Reveals Immune Regulatory Dysfunction in End-Stage Disease. Viruses 2021; 13:1597. [PMID: 34452463 PMCID: PMC8402847 DOI: 10.3390/v13081597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/31/2021] [Accepted: 08/06/2021] [Indexed: 12/11/2022] Open
Abstract
Pathogenic New World orthohantaviruses cause hantavirus cardiopulmonary syndrome (HCPS), a severe immunopathogenic disease in humans manifested by pulmonary edema and respiratory distress, with case fatality rates approaching 40%. High levels of inflammatory mediators are present in the lungs and systemic circulation of HCPS patients. Previous studies have provided insights into the pathophysiology of HCPS. However, the longitudinal correlations of innate and adaptive immune responses and disease outcomes remain unresolved. This study analyzed serial immune responses in 13 HCPS cases due to Sin Nombre orthohantavirus (SNV), with 11 severe cases requiring extracorporeal membrane oxygenation (ECMO) treatment and two mild cases. We measured viral load, levels of various cytokines, urokinase plasminogen activator (uPA), and plasminogen activator inhibitor-1 (PAI-1). We found significantly elevated levels of proinflammatory cytokines and PAI-1 in five end-stage cases. There was no difference between the expression of active uPA in survivors' and decedents' cases. However, total uPA in decedents' cases was significantly higher compared to survivors'. In some end-stage cases, uPA was refractory to PAI-1 inhibition as measured by zymography, where uPA and PAI-1 were strongly correlated to lymphocyte counts and IFN-γ. We also found bacterial co-infection influencing the etiology and outcome of immune response in two cases. Unsupervised Principal Component Analysis and hierarchical cluster analyses resolved separate waves of correlated immune mediators expressed in one case patient due to a sequential co-infection of bacteria and SNV. Overall, a robust proinflammatory immune response, characterized by an imbalance in T helper 17 (Th17) and regulatory T-cells (Treg) subsets, was correlated with dysregulated inflammation and mortality. Our sample size is small; however, the core differences correlated to survivors and end-stage HCPS are instructive.
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Affiliation(s)
- Peter Simons
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; (P.S.); (V.B.); (C.T.); (D.C.-R.)
| | - Yan Guo
- Bioinformatics Shared Resource Center, Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA;
| | - Virginie Bondu
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; (P.S.); (V.B.); (C.T.); (D.C.-R.)
| | - Susan L. Tigert
- Clinical and Translational Science Center (CTSC), University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA;
| | - Michelle Harkins
- Division of Infectious Diseases, Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque, NM 87131, USA; (M.H.); (S.G.); (S.B.)
| | - Samuel Goodfellow
- Division of Infectious Diseases, Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque, NM 87131, USA; (M.H.); (S.G.); (S.B.)
| | - Cana Tompkins
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; (P.S.); (V.B.); (C.T.); (D.C.-R.)
| | - Devon Chabot-Richards
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; (P.S.); (V.B.); (C.T.); (D.C.-R.)
| | - Xuexian O. Yang
- Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA;
| | - Laura Gonzalez Bosc
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA;
| | - Steven Bradfute
- Division of Infectious Diseases, Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque, NM 87131, USA; (M.H.); (S.G.); (S.B.)
| | - Daniel A. Lawrence
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA;
| | - Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; (P.S.); (V.B.); (C.T.); (D.C.-R.)
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4
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Simons P, Rinaldi DA, Bondu V, Kell AM, Bradfute S, Lidke D, Buranda T. Integrin activation is an essential component of SARS-CoV-2 infection. bioRxiv 2021. [PMID: 34312625 DOI: 10.1101/2021.07.20.453118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cellular entry of coronaviruses depends on binding of the viral spike (S) protein to a specific cellular receptor, the angiotensin-converting enzyme 2 (ACE2). Furthermore, the viral spike protein expresses an RGD motif, suggesting that cell surface integrins may be attachment co-receptors. However, using infectious SARS-CoV-2 requires a biosafety level 3 laboratory (BSL-3), which limits the techniques that can be used to study the mechanism of cell entry. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating both cell entry and productive infection. We used flow cytometry and confocal fluorescence microscopy to show that fluorescently labeled SARS-CoV-2 R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn 2+ , which activates integrins and induces integrin extension, enhances cell binding and entry of SARS-CoV-2 R18 in proportion to the fraction of integrins activated. We also show that one class of integrin antagonist, which binds to the αI MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2 R18 with basal state integrins, but is ineffective against Mn 2+ -activated integrins. At the same time, RGD-integrin antagonists inhibited SARS-CoV-2 R18 binding regardless of integrin activity state. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand binding function of integrins via a talin dependent mechanism and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by Gα 13 and induces cell spreading, retraction, migration, and proliferation. Using cell-permeable peptide inhibitors of talin, and Gα 13 binding to the cytoplasmic tail of an integrin's β subunit, we further demonstrate that talin-mediated signaling is essential for productive infection by SARS-CoV-2.
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Tatsumi K, Hisada Y, Connolly AMF, Buranda T, Mackman N. Patients with severe orthohantavirus cardiopulmonary syndrome due to Sin Nombre Virus infection have increased circulating extracellular vesicle tissue factor and an activated coagulation system. Thromb Res 2019; 179:31-33. [DOI: 10.1016/j.thromres.2019.04.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/25/2019] [Accepted: 04/30/2019] [Indexed: 12/22/2022]
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6
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Rivas AL, Hoogesteijn AL, Antoniades A, Tomazou M, Buranda T, Perkins DJ, Fair JM, Durvasula R, Fasina FO, Tegos GP, van Regenmortel MHV. Assessing the Dynamics and Complexity of Disease Pathogenicity Using 4-Dimensional Immunological Data. Front Immunol 2019; 10:1258. [PMID: 31249569 PMCID: PMC6582751 DOI: 10.3389/fimmu.2019.01258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 05/17/2019] [Indexed: 02/05/2023] Open
Abstract
Investigating disease pathogenesis and personalized prognostics are major biomedical needs. Because patients sharing the same diagnosis can experience different outcomes, such as survival or death, physicians need new personalized tools, including those that rapidly differentiate several inflammatory phases. To address these topics, a pattern recognition-based method (PRM) that follows an inverse problem approach was designed to assess, in <10 min, eight concepts: synergy, pleiotropy, complexity, dynamics, ambiguity, circularity, personalized outcomes, and explanatory prognostics (pathogenesis). By creating thousands of secondary combinations derived from blood leukocyte data, the PRM measures synergic, pleiotropic, complex and dynamic data interactions, which provide personalized prognostics while some undesirable features-such as false results and the ambiguity associated with data circularity-are prevented. Here, this method is compared to Principal Component Analysis (PCA) and evaluated with data collected from hantavirus-infected humans and birds that appeared to be healthy. When human data were examined, the PRM predicted 96.9 % of all surviving patients while PCA did not distinguish outcomes. Demonstrating applications in personalized prognosis, eight PRM data structures sufficed to identify all but one of the survivors. Dynamic data patterns also distinguished survivors from non-survivors, as well as one subset of non-survivors, which exhibited chronic inflammation. When the PRM explored avian data, it differentiated immune profiles consistent with no, early, or late inflammation. Yet, PCA did not recognize patterns in avian data. Findings support the notion that immune responses, while variable, are rather deterministic: a low number of complex and dynamic data combinations may be enough to, rapidly, unmask conditions that are neither directly observable nor reliably forecasted.
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Affiliation(s)
- Ariel L. Rivas
- School of Medicine, Center for Global Health-Division of Infectious Diseases, University of New Mexico, Albuquerque, NM, United States
- *Correspondence: Ariel L. Rivas
| | - Almira L. Hoogesteijn
- Human Ecology, Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mérida, Mexico
| | | | | | - Tione Buranda
- Department of Pathology, School of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Douglas J. Perkins
- School of Medicine, Center for Global Health-Division of Infectious Diseases, University of New Mexico, Albuquerque, NM, United States
| | - Jeanne M. Fair
- Biosecurity and Public Health, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Ravi Durvasula
- Loyola University Medical Center, Chicago, IL, United States
| | - Folorunso O. Fasina
- Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa
- Food and Agriculture Organization of the United Nations, Dar es Salaam, Tanzania
| | | | - Marc H. V. van Regenmortel
- Centre National de la Recherche Scientifique (CNRS), School of Biotechnology, University of Strasbourg, Strasbourg, France
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7
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Bondu V, Bitting C, Poland VL, Hanson JA, Harkins MS, Lathrop S, Nolte KB, Lawrence DA, Buranda T. Upregulation of P2Y 2R, Active uPA, and PAI-1 Are Essential Components of Hantavirus Cardiopulmonary Syndrome. Front Cell Infect Microbiol 2018; 8:169. [PMID: 29930915 PMCID: PMC6001748 DOI: 10.3389/fcimb.2018.00169] [Citation(s) in RCA: 13] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/03/2018] [Indexed: 12/13/2022] Open
Abstract
Sin Nombre virus (SNV) causes hantavirus cardiopulmonary pulmonary syndrome (HCPS) with the loss of pulmonary vascular endothelial integrity, and pulmonary edema without causing cytopathic effects on the vascular endothelium. HCPS is associated primarily with a dysregulated immune response. We previously found occult signs of hemostatic imbalance in the form of a sharp >30-100 fold increase in the expression of plasminogen activator inhibitor type 1 (PAI-1), in serial blood plasma draws of terminal stage-patients. However, the mechanism of the increase in PAI-1 remains unclear. PAI-1 is a primary inhibitor of fibrinolysis caused by tissue plasminogen activator (tPA) and urokinase plasminogen activator plasma (uPA). Here, we investigate factors that contribute to PAI-1 upregulation during HCPS. Using zymography, we found evidence of PAI-1-refractory uPA activity and no tPA activity in plasma samples drawn from HCPS patients. The sole prevalence of uPA activity suggested that severe inflammation drove PAI-1 activity. We have recently reported that the P2Y2 receptor (P2Y2R) mediates SNV infectivity by interacting in cis with β3 integrins, which activates the latter during infection. P2Y2R is a known effector for several biological processes relevant to HCPS pathogenesis, such as upregulation of tissue factor (TF), a primary initiator of the coagulation cascade, stimulating vascular permeability and leukocyte homing to sites of infection. As P2Y2R is prone to upregulation under conditions of inflammation, we compared the expression level of P2Y2R in formalin fixed tissues of HCPS decedents using a TaqMan assay and immunohistochemistry. Our TaqMan results show that the expression of P2Y2R is upregulated significantly in HCPS cases compared to non- HCPS controls (P < 0.001). Immunohistochemistry showed that lung macrophages were the primary reservoir of high and coincident localization of P2Y2R, uPA, PAI-1, and TF antigens. We also observed increased staining for SNV antigens in the same tissue segments where P2Y2R expression was upregulated. Conversely, sections of low P2Y2R expression showed weak manifestations of macrophages, SNV, PAI-1, and TF. Coincident localization of P2Y2R and PAI-1 on macrophage deposits suggests an inflammation-dependent mechanism of increasing pro-coagulant activity in HCPS in the absence of tissue injury.
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Affiliation(s)
- Virginie Bondu
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Casey Bitting
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Valerie L Poland
- Office of the Medical Investigator, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Joshua A Hanson
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Michelle S Harkins
- Division of Infectious Disease, Pulmonary, Critical Care, and Sleep, Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Sarah Lathrop
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States.,Office of the Medical Investigator, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Kurt B Nolte
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States.,Office of the Medical Investigator, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Daniel A Lawrence
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, United States
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Babbitt SE, Kiss A, Deffenbaugh AE, Chang YH, Bailly E, Erdjument-Bromage H, Tempst P, Buranda T, Sklar LA, Baumler J, Gogol E, Skowyra D. Retraction Notice to: ATP Hydrolysis-Dependent Disassembly of the 26S Proteasome Is Part of the Catalytic Cycle. Cell 2018; 173:804. [PMID: 29677518 DOI: 10.1016/j.cell.2018.04.009] [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: 11/16/2022]
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9
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Buranda T, Gineste C, Wu Y, Bondu V, Perez D, Lake KR, Edwards BS, Sklar LA. A High-Throughput Flow Cytometry Screen Identifies Molecules That Inhibit Hantavirus Cell Entry. SLAS Discov 2018; 23:634-645. [PMID: 29608398 DOI: 10.1177/2472555218766623] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hantaviruses cause hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS), which infects more than 200,000 people worldwide. Sin Nombre virus (SNV) and Andes virus (ANDV) cause the most severe form of HCPS, with case fatality ratios of 30%-40%. There are no specific therapies or vaccines for SNV. Using high-throughput flow cytometry, we screened the Prestwick Chemical Library for small-molecule inhibitors of the binding interaction between UV-inactivated and fluorescently labeled SNVR18 particles, and decay-accelerating factor (DAF) expressed on Tanoue B cells. Eight confirmed hit compounds from the primary screen were investigated further in secondary screens that included infection inhibition, cytotoxicity, and probe interference. Antimycin emerged as a bona fide hit compound that inhibited cellular infection of the major HCPS (SNV)- and HCPS (Hantaan)-causing viruses. Confirming our assay's ability to detect active compounds, orthogonal testing of the hit compound showed that antimycin binds directly to the virus particle and blocks recapitulation of physiologic integrin activation caused by SNV binding to the integrin PSI domain.
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Affiliation(s)
- Tione Buranda
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018.,2 Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Catherine Gineste
- 3 University of New Mexico Center for Molecular Discovery, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Yang Wu
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018
| | - Virginie Bondu
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018
| | - Dominique Perez
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018.,4 Department of Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Kaylin R Lake
- 5 Department of Biochemistry, University of New Mexico, Albuquerque, NM, USA
| | - Bruce S Edwards
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018.,3 University of New Mexico Center for Molecular Discovery, University of New Mexico School of Medicine, Albuquerque, NM, USA.,4 Department of Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Larry A Sklar
- 1 Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA, and in revised form Feb 15, 2018. Accepted for publication Mar 1, 2018.,3 University of New Mexico Center for Molecular Discovery, University of New Mexico School of Medicine, Albuquerque, NM, USA.,4 Department of Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM, USA
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10
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Bondu V, Wu C, Cao W, Simons PC, Gillette J, Zhu J, Erb L, Zhang XF, Buranda T. Low-affinity binding in cis to P2Y 2R mediates force-dependent integrin activation during hantavirus infection. Mol Biol Cell 2017; 28:2887-2903. [PMID: 28835374 PMCID: PMC5638590 DOI: 10.1091/mbc.e17-01-0082] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 02/09/2017] [Revised: 08/08/2017] [Accepted: 08/17/2017] [Indexed: 12/22/2022] Open
Abstract
Atomic force microscopy is used to establish that low-affinity integrins bind in cis to P2Y2R. Integrin activation is initiated by a membrane-normal switchblade motion triggered by integrin priming after the virus binds to the integrin PSI domain. Tensile force between the P2Y2R and unbending integrin stimulates outside-in signaling. Pathogenic hantaviruses bind to the plexin-semaphorin-integrin (PSI) domain of inactive, β3 integrins. Previous studies have implicated a cognate cis interaction between the bent conformation β5/β3 integrins and an arginine-glycine-aspartic acid (RGD) sequence in the first extracellular loop of P2Y2R. With single-molecule atomic force microscopy, we show a specific interaction between an atomic force microscopy tip decorated with recombinant αIIbβ3 integrins and (RGD)P2Y2R expressed on cell membranes. Mutation of the RGD sequence to RGE in the P2Y2R removes this interaction. Binding of inactivated and fluorescently labeled Sin Nombre virus (SNV) to the integrin PSI domain stimulates higher affinity for (RGD)P2Y2R on cells, as measured by an increase in the unbinding force. In CHO cells, stably expressing αIIbβ3 integrins, virus engagement at the integrin PSI domain, recapitulates physiologic activation of the integrin as indicated by staining with the activation-specific mAB PAC1. The data also show that blocking of the Gα13 protein from binding to the cytoplasmic domain of the β3 integrin prevents outside-in signaling and infection. We propose that the cis interaction with P2Y2R provides allosteric resistance to the membrane-normal motion associated with the switchblade model of integrin activation, where the development of tensile force yields physiological integrin activation.
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Affiliation(s)
- Virginie Bondu
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Chenyu Wu
- Department of Mechanical Engineering and Mechanics and Department of Bioengineering, Lehigh University, Bethlehem, PA 18015
| | - Wenpeng Cao
- Department of Mechanical Engineering and Mechanics and Department of Bioengineering, Lehigh University, Bethlehem, PA 18015
| | - Peter C Simons
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Jennifer Gillette
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Jieqing Zhu
- Blood Research Institute, Bloodcenter of Wisconsin, Milwaukee, WI 53226
| | - Laurie Erb
- Department of Biochemistry, 540F Bond Life Sciences Center, Columbia, MO 65211
| | - X Frank Zhang
- Department of Mechanical Engineering and Mechanics and Department of Bioengineering, Lehigh University, Bethlehem, PA 18015
| | - Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131 .,Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM 87131
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11
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Chatzipanagiotou S, Ioannidis A, Trikka-Graphakos E, Charalampaki N, Sereti C, Piccinini R, Higgins AM, Buranda T, Durvasula R, Hoogesteijn AL, Tegos GP, Rivas AL. Detecting the Hidden Properties of Immunological Data and Predicting the Mortality Risks of Infectious Syndromes. Front Immunol 2016; 7:217. [PMID: 27375617 PMCID: PMC4901050 DOI: 10.3389/fimmu.2016.00217] [Citation(s) in RCA: 5] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 05/19/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND To extract more information, the properties of infectious disease data, including hidden relationships, could be considered. Here, blood leukocyte data were explored to elucidate whether hidden information, if uncovered, could forecast mortality. METHODS Three sets of individuals (n = 132) were investigated, from whom blood leukocyte profiles and microbial tests were conducted (i) cross-sectional analyses performed at admission (before bacteriological tests were completed) from two groups of hospital patients, randomly selected at different time periods, who met septic criteria [confirmed infection and at least three systemic inflammatory response syndrome (SIRS) criteria] but lacked chronic conditions (study I, n = 36; and study II, n = 69); (ii) a similar group, tested over 3 days (n = 7); and (iii) non-infected, SIRS-negative individuals, tested once (n = 20). The data were analyzed by (i) a method that creates complex data combinations, which, based on graphic patterns, partitions the data into subsets and (ii) an approach that does not partition the data. Admission data from SIRS+/infection+ patients were related to 30-day, in-hospital mortality. RESULTS The non-partitioning approach was not informative: in both study I and study II, the leukocyte data intervals of non-survivors and survivors overlapped. In contrast, the combinatorial method distinguished two subsets that, later, showed twofold (or larger) differences in mortality. While the two subsets did not differ in gender, age, microbial species, or antimicrobial resistance, they revealed different immune profiles. Non-infected, SIRS-negative individuals did not express the high-mortality profile. Longitudinal data from septic patients displayed the pattern associated with the highest mortality within the first 24 h post-admission. Suggesting inflammation coexisted with immunosuppression, one high-mortality sub-subset displayed high neutrophil/lymphocyte ratio values and low lymphocyte percents. A second high-mortality subset showed monocyte-mediated deficiencies. Numerous within- and between-subset comparisons revealed statistically significantly different immune profiles. CONCLUSION While the analysis of non-partitioned data can result in information loss, complex (combinatorial) data structures can uncover hidden patterns, which guide data partitioning into subsets that differ in mortality rates and immune profiles. Such information can facilitate diagnostics, monitoring of disease dynamics, and evaluation of subset-specific, patient-specific therapies.
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Affiliation(s)
- S Chatzipanagiotou
- Department of Biopathology and Clinical Microbiology, Aeginition Hospital, Medical School, National and Kapodistrian University of Athens , Athens , Greece
| | - A Ioannidis
- Department of Nursing, Faculty of Human Movement and Quality of Life Sciences, University of Peloponnese , Sparta , Greece
| | - E Trikka-Graphakos
- Department of Clinical Microbiology, "Thriasio" General Hospital , Magoula , Greece
| | - N Charalampaki
- Department of Clinical Microbiology, "Thriasio" General Hospital , Magoula , Greece
| | - C Sereti
- Department of Clinical Microbiology, "Thriasio" General Hospital , Magoula , Greece
| | - R Piccinini
- Department of Veterinary Science and Public Health, University of Milan , Milan , Italy
| | - A M Higgins
- Division of Infectious Diseases, Center for Global Health, School of Medicine, University of New Mexico , Albuquerque, NM , USA
| | - T Buranda
- Department of Pathology, School of Medicine, University of New Mexico , Albuquerque, NM , USA
| | - R Durvasula
- Division of Infectious Diseases, Center for Global Health, School of Medicine, University of New Mexico , Albuquerque, NM , USA
| | - A L Hoogesteijn
- Human Ecology Department, Cinvestav , Unidad Merida , Mexico
| | - G P Tegos
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, USA; Department of Dermatology, Harvard Medical School, Boston, MA, USA; Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
| | - Ariel L Rivas
- Division of Infectious Diseases, Center for Global Health, School of Medicine, University of New Mexico , Albuquerque, NM , USA
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Guo Y, Kenney SR, Sklar LA, Buranda T, Oprea TI, Ursu O, Adams SF, Rutledge T, Muller C, Lomo L, Hudson LG, Wandinger-Ness A. Abstract 4044: R-ketorolac targets Cdc42 and Rac1 GTPases and alters ovarian tumor cell behaviors critical for invasion and metastasis. Mol Cell Biol 2015. [DOI: 10.1158/1538-7445.am2015-4044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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13
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Agola JO, Sivalingam D, Cimino DF, Simons PC, Buranda T, Sklar LA, Wandinger-Ness A. Quantitative bead-based flow cytometry for assaying Rab7 GTPase interaction with the Rab-interacting lysosomal protein (RILP) effector protein. Methods Mol Biol 2015; 1298:331-54. [PMID: 25800855 PMCID: PMC6033261 DOI: 10.1007/978-1-4939-2569-8_28] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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] [Indexed: 04/24/2023]
Abstract
Rab7 facilitates vesicular transport and delivery from early endosomes to late endosomes as well as from late endosomes to lysosomes. The role of Rab7 in vesicular transport is dependent on its interactions with effector proteins, among them Rab-interacting lysosomal protein (RILP), which aids in the recruitment of active Rab7 (GTP-bound) onto dynein-dynactin motor complexes to facilitate late endosomal transport on the cytoskeleton. Here we detail a novel bead-based flow cytometry assay to measure Rab7 interaction with the Rab-interacting lysosomal protein (RILP) effector protein and demonstrate its utility for quantitative assessment and studying drug-target interactions. The specific binding of GTP-bound Rab7 to RILP is readily demonstrated and shown to be dose-dependent and saturable enabling K d and B max determinations. Furthermore, binding is nearly instantaneous and temperature-dependent. In a novel application of the assay method, a competitive small molecule inhibitor of Rab7 nucleotide binding (CID 1067700 or ML282) is shown to inhibit the Rab7-RILP interaction. Thus, the assay is able to distinguish that the small molecule, rather than incurring the active conformation, instead 'locks' the GTPase in the inactive conformation. Together, this work demonstrates the utility of using a flow cytometry assay to quantitatively characterize protein-protein interactions involving small GTPases and which has been adapted to high-throughput screening. Further, the method provides a platform for testing small molecule effects on protein-protein interactions, which can be relevant to drug discovery and development.
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Affiliation(s)
- Jacob O Agola
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
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14
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Chigaev A, Smagley Y, Haynes MK, Ursu O, Bologa CG, Halip L, Oprea T, Waller A, Carter MB, Zhang Y, Wang W, Buranda T, Sklar LA. FRET detection of lymphocyte function-associated antigen-1 conformational extension. Mol Biol Cell 2014; 26:43-54. [PMID: 25378583 PMCID: PMC4279228 DOI: 10.1091/mbc.e14-06-1050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [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] [Indexed: 01/05/2023] Open
Abstract
Lymphocyte function–associated antigen 1 (LFA-1) and its ligands are essential for immune cell interactions. LFA-1 is regulated through conformational changes. The relationship between molecular conformation and function is unclear. Förster resonance energy transfer is used to assess LFA-1 conformation under real-time signaling conditions. Lymphocyte function–associated antigen 1 (LFA-1, CD11a/CD18, αLβ2-integrin) and its ligands are essential for adhesion between T-cells and antigen-presenting cells, formation of the immunological synapse, and other immune cell interactions. LFA-1 function is regulated through conformational changes that include the modulation of ligand binding affinity and molecular extension. However, the relationship between molecular conformation and function is unclear. Here fluorescence resonance energy transfer (FRET) with new LFA-1–specific fluorescent probes showed that triggering of the pathway used for T-cell activation induced rapid unquenching of the FRET signal consistent with extension of the molecule. Analysis of the FRET quenching at rest revealed an unexpected result that can be interpreted as a previously unknown LFA-1 conformation.
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Affiliation(s)
| | | | - Mark K Haynes
- University of New Mexico Center for Molecular Discovery, and
| | - Oleg Ursu
- University of New Mexico Center for Molecular Discovery, and Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Cristian G Bologa
- University of New Mexico Center for Molecular Discovery, and Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Liliana Halip
- Department of Computational Chemistry, Institute of Chemistry, Romanian Academy, Timisoara 300223, Romania
| | - Tudor Oprea
- University of New Mexico Center for Molecular Discovery, and Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Anna Waller
- University of New Mexico Center for Molecular Discovery, and
| | - Mark B Carter
- University of New Mexico Center for Molecular Discovery, and
| | - Yinan Zhang
- Department of Pharmaceutical Science, College of Pharmacy, University of Kentucky, Lexington, KY 40506
| | - Wei Wang
- Department of Chemistry, University of New Mexico, Albuquerque, NM 87131
| | | | - Larry A Sklar
- Department of Pathology and Cancer Center, University of New Mexico Center for Molecular Discovery, and
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15
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Termini CM, Cotter ML, Marjon KD, Buranda T, Lidke KA, Gillette JM. The membrane scaffold CD82 regulates cell adhesion by altering α4 integrin stability and molecular density. Mol Biol Cell 2014; 25:1560-73. [PMID: 24623721 PMCID: PMC4019488 DOI: 10.1091/mbc.e13-11-0660] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [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] [Indexed: 02/07/2023] Open
Abstract
Hematopoietic stem/progenitor cell (HSPC) interactions with the bone marrow microenvironment are important for maintaining HSPC self-renewal and differentiation. In recent work, we identified the tetraspanin protein, CD82, as a regulator of HPSC adhesion and homing to the bone marrow, although the mechanism by which CD82 mediated adhesion was unclear. In the present study, we determine that CD82 expression alters cell-matrix adhesion, as well as integrin surface expression. By combining the superresolution microscopy imaging technique, direct stochastic optical reconstruction microscopy, with protein clustering algorithms, we identify a critical role for CD82 in regulating the membrane organization of α4 integrin subunits. Our data demonstrate that CD82 overexpression increases the molecular density of α4 within membrane clusters, thereby increasing cellular adhesion. Furthermore, we find that the tight packing of α4 into membrane clusters depend on CD82 palmitoylation and the presence of α4 integrin ligands. In combination, these results provide unique quantifiable evidence of CD82's contribution to the spatial arrangement of integrins within the plasma membrane and suggest that regulation of integrin density by tetraspanins is a critical component of cell adhesion.
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Affiliation(s)
- Christina M Termini
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Maura L Cotter
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Kristopher D Marjon
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Tione Buranda
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Keith A Lidke
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131
| | - Jennifer M Gillette
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
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16
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Buranda T, Swanson S, Bondu V, Schaefer L, Maclean J, Mo Z, Wycoff K, Belle A, Hjelle B. Equilibrium and kinetics of Sin Nombre hantavirus binding at DAF/CD55 functionalized bead surfaces. Viruses 2014; 6:1091-111. [PMID: 24618810 PMCID: PMC3970141 DOI: 10.3390/v6031091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [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: 11/30/2013] [Revised: 02/13/2014] [Accepted: 02/23/2014] [Indexed: 12/14/2022] Open
Abstract
Decay accelerating factor (DAF/CD55) is targeted by many pathogens for cell entry. It has been implicated as a co-receptor for hantaviruses. To examine the binding of hantaviruses to DAF, we describe the use of Protein G beads for binding human IgG Fc domain-functionalized DAF ((DAF)2-Fc). When mixed with Protein G beads the resulting DAF beads can be used as a generalizable platform for measuring kinetic and equilibrium binding constants of DAF binding targets. The hantavirus interaction has high affinity (24–30 nM; kon ~ 105 M−1s−1, koff ~ 0.0045 s−1). The bivalent (DAF)2-Fc/SNV data agree with hantavirus binding to DAF expressed on Tanoue B cells (Kd = 14.0 nM). Monovalent affinity interaction between SNV and recombinant DAF of 58.0 nM is determined from competition binding. This study serves a dual purpose of presenting a convenient and quantitative approach of measuring binding affinities between DAF and the many cognate viral and bacterial ligands and providing new data on the binding constant of DAF and Sin Nombre hantavirus. Knowledge of the equilibrium binding constant allows for the determination of the relative fractions of bound and free virus particles in cell entry assays. This is important for drug discovery assays for cell entry inhibitors.
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Affiliation(s)
- Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, MSC08 4640, Albuquerque, NM 87131, USA.
| | - Scarlett Swanson
- Department of Pathology, University of New Mexico School of Medicine, MSC08 4640, Albuquerque, NM 87131, USA.
| | - Virginie Bondu
- Department of Pathology, University of New Mexico School of Medicine, MSC08 4640, Albuquerque, NM 87131, USA.
| | - Leah Schaefer
- Planet Biotechnology Inc., 25571 Clawiter Road, Hayward, CA 94545, USA.
| | - James Maclean
- Planet Biotechnology Inc., 25571 Clawiter Road, Hayward, CA 94545, USA.
| | - Zhenzhen Mo
- Planet Biotechnology Inc., 25571 Clawiter Road, Hayward, CA 94545, USA.
| | - Keith Wycoff
- Planet Biotechnology Inc., 25571 Clawiter Road, Hayward, CA 94545, USA.
| | - Archana Belle
- Planet Biotechnology Inc., 25571 Clawiter Road, Hayward, CA 94545, USA.
| | - Brian Hjelle
- Department of Pathology, University of New Mexico School of Medicine, MSC08 4640, Albuquerque, NM 87131, USA.
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17
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Hong L, Kenney SR, Phillips GK, Simpson D, Schroeder CE, Nöth J, Romero E, Swanson S, Waller A, Strouse JJ, Carter M, Chigaev A, Ursu O, Oprea T, Hjelle B, Golden JE, Aubé J, Hudson LG, Buranda T, Sklar LA, Wandinger-Ness A. Characterization of a Cdc42 protein inhibitor and its use as a molecular probe. J Biol Chem 2014. [DOI: 10.1074/jbc.a112.435941] [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: 11/06/2022] Open
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18
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Guo Y, Kenney SR, Romero E, Oprea T, Adams S, Muller C, Sklar L, Buranda T, Hudson L, Wandinger-Ness A. Abstract B81: Selected NSAIDs target GTPases for ovarian cancer therapy. Clin Cancer Res 2013. [DOI: 10.1158/1078-0432.ovca13-b81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Rac1 and Cdc42 GTPases are key regulators of actin reorganization, cell mobility, cell-cell and cell-extracellular matrix (ECM) adhesion, whose activities are found closely correlated with tumor cell properties (increased proliferation, migration and adhesion), which are important for tumor expansion and malignant progression. We found that both the constitutively active Rac1b and Cdc42 GTPases are overexpressed in primary ovarian tumors and cancer cell lines. Using high throughput screening and computational methods, selected non-steroidal anti-inflammatory drugs (NSAIDs) were identified as regulators of Rac1 and Cdc42 in vitro, which we confirmed in cellular assays and xenograft animal model studies. Among the NSAIDs, ketorolac, inhibited cell adhesion, migration and invasion. When administrated intraperitoneally (IP) in a human xenograft model of ovarian cancer a 3-4 fold reduction in tumor cell number and decreased total tumor burden resulted. The S-enantiomer of ketorolac is a well-established inhibitor of cyclooxygenase (COX) enzymes. We determined that R-enantiomer had little activity against COX and using G-LISA assays to measure GTPase activation established that R-, but not S-ketorolac was an effective GTPase inhibitor. These data prompted us to conduct a clinical pilot study in ovarian cancer patients assessing the bioavailability and impact of clinically approved Toradol (racemic [R, S] ketorolac administrated clinically for pain after surgery) on tumor cell behaviors. Patient serum and ascites samples analyzed by HPLC established that ketorolac was detectable in the ascites fluid within 1 hour after intravenous (IV) administration with predominantly the R-form persisting after 6 hours. Serum concentrations were found to predict ascites concentrations. Purified tumor cells from fresh patient ascites (identified by tumor markers MUC16, EpCAM) when treated in vitro with ketorolac exhibited reduced adhesion to ECM; furthermore, GTPase activity assays demonstrated that R-, but not S-ketorolac significantly inhibited Cdc42 activity. Post-Toradol treatment patient ascites samples also exhibited reduced Cdc42 activity at all timepoints. In sum, we show that the R-enantiomers of selected NSAIDs are novel chemical entities that selectively target Rho-family GTPases and facilitate the development of new chemical entities based on these scaffolds. Such mechanistic tumor-relevant functional activities have not been described previously and suggest that investigation of FDA approved NSAIDs offer opportunities for repurposing and rapid human translation for the treatment of ovarian cancer. The composite results validate Rho-family GTPases and their downstream effectors as potential prognostic indicators and as therapeutic targets for ovarian cancer.
Citation Format: Yuna Guo, S. Ray Kenney, Elsa Romero, Tudor Oprea, Sarah Adams, Carolyn Muller, Larry Sklar, Tione Buranda, Laurie Hudson, Angela Wandinger-Ness. Selected NSAIDs target GTPases for ovarian cancer therapy. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B81.
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Affiliation(s)
- Yuna Guo
- University of New Mexico, Albuquerque, NM
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19
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Buranda T, BasuRay S, Swanson S, Agola J, Bondu V, Wandinger-Ness A. Rapid parallel flow cytometry assays of active GTPases using effector beads. Anal Biochem 2013; 442:149-57. [PMID: 23928044 DOI: 10.1016/j.ab.2013.07.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [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: 06/13/2013] [Revised: 07/23/2013] [Accepted: 07/28/2013] [Indexed: 12/13/2022]
Abstract
We describe a rapid assay for measuring the cellular activity of small guanine triphosphatases (GTPases) in response to a specific stimulus. Effector-functionalized beads are used to quantify in parallel multiple GTP-bound GTPases in the same cell lysate by flow cytometry. In a biologically relevant example, five different Ras family GTPases are shown for the first time to be involved in a concerted signaling cascade downstream of receptor ligation by Sin Nombre hantavirus.
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Affiliation(s)
- Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA; Center for Infectious Diseases and Immunity, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
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20
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Hong L, Kenney SR, Phillips GK, Simpson D, Schroeder CE, Nöth J, Romero E, Swanson S, Waller A, Strouse JJ, Carter M, Chigaev A, Ursu O, Oprea T, Hjelle B, Golden JE, Aubé J, Hudson LG, Buranda T, Sklar LA, Wandinger-Ness A. Characterization of a Cdc42 protein inhibitor and its use as a molecular probe. J Biol Chem 2013; 288:8531-8543. [PMID: 23382385 PMCID: PMC3605667 DOI: 10.1074/jbc.m112.435941] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [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] [Indexed: 12/19/2022] Open
Abstract
Cdc42 plays important roles in cytoskeleton organization, cell cycle progression, signal transduction, and vesicle trafficking. Overactive Cdc42 has been implicated in the pathology of cancers, immune diseases, and neuronal disorders. Therefore, Cdc42 inhibitors would be useful in probing molecular pathways and could have therapeutic potential. Previous inhibitors have lacked selectivity and trended toward toxicity. We report here the characterization of a Cdc42-selective guanine nucleotide binding lead inhibitor that was identified by high throughput screening. A second active analog was identified via structure-activity relationship studies. The compounds demonstrated excellent selectivity with no inhibition toward Rho and Rac in the same GTPase family. Biochemical characterization showed that the compounds act as noncompetitive allosteric inhibitors. When tested in cellular assays, the lead compound inhibited Cdc42-related filopodia formation and cell migration. The lead compound was also used to clarify the involvement of Cdc42 in the Sin Nombre virus internalization and the signaling pathway of integrin VLA-4. Together, these data present the characterization of a novel Cdc42-selective allosteric inhibitor and a related analog, the use of which will facilitate drug development targeting Cdc42-related diseases and molecular pathway studies that involve GTPases.
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Affiliation(s)
- Lin Hong
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131
| | - S Ray Kenney
- Department of Pharmaceutical Sciences, University of New Mexico, Albuquerque, New Mexico 87131
| | - Genevieve K Phillips
- Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131
| | - Denise Simpson
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047
| | - Chad E Schroeder
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047
| | - Julica Nöth
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047
| | - Elsa Romero
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Scarlett Swanson
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Anna Waller
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131
| | - J Jacob Strouse
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131
| | - Mark Carter
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131
| | - Alexandre Chigaev
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Oleg Ursu
- University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131; Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131; Department of Biochemistry and Molecular Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Tudor Oprea
- University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131; Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131; Department of Biochemistry and Molecular Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Brian Hjelle
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Jennifer E Golden
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047
| | - Jeffrey Aubé
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047; Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045
| | - Laurie G Hudson
- Department of Pharmaceutical Sciences, University of New Mexico, Albuquerque, New Mexico 87131; Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131
| | - Tione Buranda
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Larry A Sklar
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; University of New Mexico (UNM) Center for Molecular Discovery, University of New Mexico, Albuquerque, New Mexico 87131; Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131.
| | - Angela Wandinger-Ness
- Department of Pathology, University of New Mexico, Albuquerque, New Mexico 87131; Department of Pharmaceutical Sciences, University of New Mexico, Albuquerque, New Mexico 87131.
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21
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Agola JO, Hong L, Surviladze Z, Ursu O, Waller A, Strouse JJ, Simpson DS, Schroeder CE, Oprea TI, Golden JE, Aubé J, Buranda T, Sklar LA, Wandinger-Ness A. A competitive nucleotide binding inhibitor: in vitro characterization of Rab7 GTPase inhibition. ACS Chem Biol 2012; 7:1095-108. [PMID: 22486388 DOI: 10.1021/cb3001099] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Mapping the functionality of GTPases through small molecule inhibitors represents an underexplored area in large part due to the lack of suitable compounds. Here we report on the small chemical molecule 2-(benzoylcarbamothioylamino)-5,5-dimethyl-4,7-dihydrothieno[2,3-c]pyran-3-carboxylic acid (PubChem CID 1067700) as an inhibitor of nucleotide binding by Ras-related GTPases. The mechanism of action of this pan-GTPase inhibitor was characterized in the context of the Rab7 GTPase as there are no known inhibitors of Rab GTPases. Bead-based flow cytometry established that CID 1067700 has significant inhibitory potency on Rab7 nucleotide binding with nanomolar inhibitor (K(i)) values and an inhibitory response of ≥97% for BODIPY-GTP and BODIPY-GDP binding. Other tested GTPases exhibited significantly lower responses. The compound behaves as a competitive inhibitor of Rab7 nucleotide binding based on both equilibrium binding and dissociation assays. Molecular docking analyses are compatible with CID 1067700 fitting into the nucleotide binding pocket of the GTP-conformer of Rab7. On the GDP-conformer, the molecule has greater solvent exposure and significantly less protein interaction relative to GDP, offering a molecular rationale for the experimental results. Structural features pertinent to CID 1067700 inhibitory activity have been identified through initial structure-activity analyses and identified a molecular scaffold that may serve in the generation of more selective probes for Rab7 and other GTPases. Taken together, our study has identified the first competitive GTPase inhibitor and demonstrated the potential utility of the compound for dissecting the enzymology of the Rab7 GTPase, as well as serving as a model for other small molecular weight GTPase inhibitors.
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Affiliation(s)
| | | | | | | | | | | | - Denise S. Simpson
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047,
United States
| | - Chad E. Schroeder
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047,
United States
| | | | - Jennifer E. Golden
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047,
United States
| | - Jeffrey Aubé
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas 66047,
United States
- Department of Medicinal
Chemistry, University of Kansas, Lawrence,
Kansas 66047, United
States
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Abstract
In flow cytometry, the quantitation of fluorophore-tagged ligands and receptors on cells or at particulate surfaces is achieved by the use of standard beads of known calibration. To the best of our knowledge, only those calibration beads based on fluorescein, EGFP, phycoerythyrin and allophycocyanine are readily available from commercial sources. Because fluorophore-based standards are specific to the selected fluorophore tag, their applicability is limited to the spectral region of resonance. Since quantum dots can be photo-excited over a continuous and broad spectral range governed by their size, it is possible to match the spectral range and width (absorbance and emission) of a wide range of fluorophores with appropriate quantum dots. Accordingly, quantitation of site coverage of the target fluorophores can be readily achieved using quantum dots whose emission spectra overlaps with the target fluorophore.This chapter focuses on the relevant spectroscopic concepts and molecular assembly of quantum dot fluorescence calibration beads. We first examine the measurement and applicability of spectroscopic parameters, ε, φ, and %T to fluorescence calibration standards, where ε is the absorption coefficient of the fluorophore, φ is the quantum yield of the fluorophore, and %T is the percent fraction of emitted light that is transmitted by the bandpass filter at the detector PMT. The modular construction of beads decorated with discrete quantities of quantum dots with defined spectroscopic parameters is presented in the context of a generalizable approach to calibrated measurements of fluorescence in flow cytometry.
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Affiliation(s)
- Tione Buranda
- Department of Pathology and Cancer Center, University of New Mexico School of Medicine, Albuquerque, NM, USA.
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Buranda T, Wu Y, Perez D, Chigaev A, Sklar LA. Real-time partitioning of octadecyl rhodamine B into bead-supported lipid bilayer membranes revealing quantitative differences in saturable binding sites in DOPC and 1:1:1 DOPC/SM/cholesterol membranes. J Phys Chem B 2010; 114:1336-49. [PMID: 20043651 DOI: 10.1021/jp906648q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantitative analysis of the staining of cell membranes with the cationic amphiphile, octadecyl rhodamine B (R18), is confounded by probe aggregation and changes to the probes' absorption cross section and emission quantum yield. In this paper, flow cytometry, quantum-dot-based fluorescence calibration beads, and FRET were used to examine real-time transfer of R18 from water to two limiting models of the cellular plasma membrane, namely, a single-component disordered membrane, dioleoyl-L-alpha-phosphatidylcholine (DOPC), and a ternary mixture of DOPC, cholesterol, and sphingomyelin (DSC) membranes, reconstituted on spherical and monodisperse glass beads (lipobeads). The quenching of R18 was analyzed as the probe concentration was raised from 0 to 10 mol % in membranes. The data show a > 2-fold enhancement in the quenching level of the probes that were reconstituted in DSC relative to DOPC membranes at the highest concentration of R18. We have parametrized the propagation of concentration-dependent quenching as a function of real-time binding of R18 to lipobeads. In this way, phenomenological kinetics of serum-albumin-mediated transfer of R18 from the aqueous phase to DOPC and DSC membranes could be evaluated under optimal conditions where the critical aggregation concentration (CAC) of the probe is defined as 14 nM. The mass action kinetics of association of R18 with DOPC and DSC lipobeads are shown to be similar. However, the saturable capacity for accepting exogenous probes is found to be 37% higher in DOPC relative to that for DSC membranes. The difference is comparable to the disparity in the average molecular areas of DOPC and DSC membranes. Finally, this analysis shows little difference in the spectral overlap integrals of the emission spectrum of a fluorescein derivative donor and the absorption spectrum of either monomeric or simulated spectrum of dimeric R18. This approach represents a first step toward a nanoscale probing of membrane heterogeneity in living cells by analyzing differential local FRET among sites of unique receptor expression in living cells.
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Affiliation(s)
- Tione Buranda
- Department of Pathology and Cancer Center, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA.
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Chemburu S, Ji E, Casana Y, Wu Y, Buranda T, Schanze KS, Lopez GP, Whitten DG. Conjugated polyelectrolyte supported bead based assays for phospholipase A2 activity. J Phys Chem B 2008; 112:14492-9. [PMID: 18808092 DOI: 10.1021/jp803358j] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A fluorescence based assay for human serum-derived phospholipase activity has been developed in which cationic conjugated polyelectrolytes are supported on silica microspheres. The polymer-coated beads are overcoated with an anionic phospholipid (1,2-dimyristoyl-sn-glycero-3-[phospho- rac-(1-glycerol)) (DMPG) to provide "lipobeads" that serve as a sensor for PLA2. The lipid serves a dual role as a substrate for PLA2 and an agent to attenuate quenching of the polymer fluorescence by the external electron transfer quencher 9,10-anthraquinone-2,6-disulfonic acid (AQS). In this case quenching of the polymer fluorescence by AQS increases as the PLA2 digests the lipid. The lipid can also be used itself as a quencher and substrate by employing a small amount of energy transfer quencher substituted lipid in the DMPG. In this case the fluorescence of the polymer is quenched when the lipid layer is intact; as the enzyme digests the lipid, the fluorescence of the polymer is restored. The sensing of PLA2 activity has been studied both by monitoring fluorescence changes in a multiwell plate reader and by flow cytometry. The assay exhibits good sensitivity with EC50 values in the nanomolar range.
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Affiliation(s)
- Sireesha Chemburu
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Schwartz SL, Tessema M, Buranda T, Pylypenko O, Rak A, Simons PC, Surviladze Z, Sklar LA, Wandinger-Ness A. Flow cytometry for real-time measurement of guanine nucleotide binding and exchange by Ras-like GTPases. Anal Biochem 2008; 381:258-66. [PMID: 18638444 DOI: 10.1016/j.ab.2008.06.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [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: 06/13/2008] [Accepted: 06/30/2008] [Indexed: 11/18/2022]
Abstract
Ras-like small GTPases cycle between GTP-bound active and GDP-bound inactive conformational states to regulate diverse cellular processes. Despite their importance, detailed kinetic or comparative studies of family members are rarely undertaken due to the lack of real-time assays measuring nucleotide binding or exchange. Here we report a bead-based flow cytometric assay that quantitatively measures the nucleotide binding properties of glutathione-S-transferase (GST) chimeras for prototypical Ras family members Rab7 and Rho. Measurements are possible in the presence or absence of Mg(2+), with magnesium cations principally increasing affinity and slowing nucleotide dissociation rates 8- to 10-fold. GST-Rab7 exhibited a 3-fold higher affinity for guanosine diphosphate (GDP) relative to guanosine triphosphate (GTP) that is consistent with a 3-fold slower dissociation rate of GDP. Strikingly, GST-Rab7 had a marked preference for GTP with ribose ring-conjugated BODIPY FL. The more commonly used gamma-NH-conjugated BODIPY FL GTP analogue failed to bind to GST-Rab7. In contrast, both BODIPY analogues bound equally well to GST-RhoA and GST-RhoC. Comparisons of the GST-Rab7 and GST-RhoA GTP binding pockets provide a structural basis for the observed binding differences. In sum, the flow cytometric assay can be used to measure nucleotide binding properties of GTPases in real time and to quantitatively assess differences between GTPases.
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Affiliation(s)
- Samantha L Schwartz
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131, USA
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Wu Y, Buranda T, Simons PC, Lopez GP, McIntire WE, Garrison JC, Prossnitz ER, Sklar LA. Rapid-mix flow cytometry measurements of subsecond regulation of G protein-coupled receptor ternary complex dynamics by guanine nucleotides. Anal Biochem 2007; 371:10-20. [PMID: 17904091 PMCID: PMC2254650 DOI: 10.1016/j.ab.2007.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [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: 04/10/2007] [Revised: 07/13/2007] [Accepted: 08/06/2007] [Indexed: 01/28/2023]
Abstract
We have used rapid-mix flow cytometry to analyze the early subsecond dynamics of the disassembly of ternary complexes of G protein-coupled receptors (GPCRs) immobilized on beads to examine individual steps associated with guanine nucleotide activation. Our earlier studies suggested that the slow dissociation of Galpha and Gbetagamma subunits was unlikely to be an essential component of cell activation. However, these studies did not have adequate time resolution to define precisely the disassembly kinetics. Ternary complexes were assembled using three formyl peptide receptor constructs (wild type, formyl peptide receptor-Galpha(i2) fusion, and formyl peptide receptor-green fluorescent protein fusion) and two isotypes of the alpha subunit (alpha(i2) and alpha(i3)) and betagamma dimer (beta(1)gamma(2) and beta(4)gamma(2)). At saturating nucleotide levels, the disassembly of a significant fraction of ternary complexes occurred on a subsecond time frame for alpha(i2) complexes and tau(1/2)< or =4s for alpha(i3) complexes, time scales that are compatible with cell activation. beta(1)gamma(2) isotype complexes were generally more stable than beta(4)gamma(2)-associated complexes. The comparison of the three constructs, however, proved that the fast step was associated with the separation of receptor and G protein and that the dissociation of the ligand or of the alpha and betagamma subunits was slower. These results are compatible with a cell activation model involving G protein conformational changes rather than disassembly of Galphabetagamma heterotrimer.
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Affiliation(s)
| | | | | | | | | | | | | | - Larry A. Sklar
- To whom correspondence should be addressed: Larry A Sklar: Department of Pathology and Cancer Research Facility, University of New Mexico Health Sciences Center, MSC 116020 Albuquerque, New Mexico 87131. . Tel: (505) 272-6892; Fax: (505) 272-6995
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Chigaev A, Waller A, Zwartz GJ, Buranda T, Sklar LA. Regulation of cell adhesion by affinity and conformational unbending of alpha4beta1 integrin. J Immunol 2007; 178:6828-39. [PMID: 17513731 DOI: 10.4049/jimmunol.178.11.6828] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rapid activation of integrins in response to chemokine-induced signaling serves as a basis for leukocyte arrest on inflamed endothelium. Current models of integrin activation include increased affinity for ligand, molecular extension, and others. In this study, using real-time fluorescence resonance energy transfer to assess alpha(4)beta(1) integrin conformational unbending and fluorescent ligand binding to assess affinity, we report at least four receptor states with independent regulation of affinity and unbending. Moreover, kinetic analysis of chemokine-induced integrin conformational unbending and ligand-binding affinity revealed conditions under which the affinity change was transient whereas the unbending was sustained. In a VLA-4/VCAM-1-specific myeloid cell adhesion model system, changes in the affinity of the VLA-4-binding pocket were reflected in rapid cell aggregation and disaggregation. However, the initial rate of cell aggregation increased 9-fold upon activation, of which only 2.5-fold was attributable to the increased affinity of the binding pocket. These data show that independent regulation of affinity and conformational unbending represents a novel and fundamental mechanism for regulation of integrin-dependent adhesion in which the increased affinity appears to account primarily for the increasing lifetime of the alpha(4)beta(1) integrin/VCAM-1 bond, whereas the unbending accounts for the increased capture efficiency.
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Affiliation(s)
- Alexandre Chigaev
- Department of Pathology and Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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Wu Y, Lopez GP, Sklar LA, Buranda T. Spectroscopic characterization of streptavidin functionalized quantum dots. Anal Biochem 2007; 364:193-203. [PMID: 17368555 PMCID: PMC2018650 DOI: 10.1016/j.ab.2007.02.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [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: 12/23/2006] [Revised: 02/06/2007] [Accepted: 02/07/2007] [Indexed: 11/24/2022]
Abstract
The spectroscopic properties of quantum dots can be strongly influenced by the conditions of their synthesis. In this work, we have characterized several spectroscopic properties of commercial, streptavidin functionalized quantum dots (QD525, lot 1005-0045, and QD585, lot 0905-0031, from Invitrogen). This is the first step in the development of calibration beads to be used in a generalizable quantification scheme of multiple fluorescent tags in flow cytometry or microscopy applications. We used light absorption, photoexcitation, and emission spectra, together with excited state lifetime measurements, to characterize their spectroscopic behavior, concentrating on the 400- to 500-nm wavelength ranges that are important in biological applications. Our data show an anomalous dependence of emission spectrum, lifetimes, and quantum yield (QY) on excitation wavelength that is particularly pronounced in the QD525. For QD525, QY values ranged from 0.2 at 480 nm excitation up to 0.4 at 450 nm and down again to 0.15 at 350 nm. For QD585, QY values were constant at 0.2 between 500 and 400 nm, but they dropped to 0.1 at 350 nm. We attribute the wavelength dependencies to heterogeneity in size and surface defects in the QD525, consistent with characteristics described previously in the chemistry literature. The results are discussed in the context of bridging the gap between what is currently known in the physical chemistry literature of quantum dots and the quantitative needs of assay development in biological applications.
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Affiliation(s)
- Yang Wu
- Pathology and Cancer Center, University of New Mexico School of Medicine
| | - Gabriel P. Lopez
- Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, 87131
| | - Larry A. Sklar
- Pathology and Cancer Center, University of New Mexico School of Medicine
| | - Tione Buranda
- Pathology and Cancer Center, University of New Mexico School of Medicine
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Wu Y, Campos SK, Lopez GP, Ozbun MA, Sklar LA, Buranda T. The development of quantum dot calibration beads and quantitative multicolor bioassays in flow cytometry and microscopy. Anal Biochem 2007; 364:180-92. [PMID: 17397793 PMCID: PMC2018651 DOI: 10.1016/j.ab.2007.02.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [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] [Received: 12/22/2006] [Revised: 02/06/2007] [Accepted: 02/07/2007] [Indexed: 11/21/2022]
Abstract
The use of fluorescence calibration beads has been the hallmark of quantitative flow cytometry. It has enabled the direct comparison of interlaboratory data as well as quality control in clinical flow cytometry. In this article, we describe a simple method for producing color-generalizable calibration beads based on streptavidin functionalized quantum dots. Based on their broad absorption spectra and relatively narrow emission, which is tunable on the basis of dot size, quantum dot calibration beads can be made for any fluorophore that matches their emission color. In an earlier publication, we characterized the spectroscopic properties of commercial streptavidin functionalized dots (Invitrogen). Here we describe the molecular assembly of these dots on biotinylated beads. The law of mass action is used to readily define the site densities of the dots on the beads. The applicability of these beads is tested against the industry standard, namely commercial fluorescein calibration beads. The utility of the calibration beads is also extended to the characterization surface densities of dot-labeled epidermal growth factor ligands as well as quantitative indicators of the binding of dot-labeled virus particles to cells.
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Affiliation(s)
- Yang Wu
- Department of Pathology and Cancer Center, University of New Mexico, Albuquerque, NM 87131, USA
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Buranda T, Waller A, Wu Y, Simons PC, Biggs S, Prossnitz ER, Sklar LA. Some mechanistic insights into GPCR activation from detergent-solubilized ternary complexes on beads. Adv Protein Chem 2007; 74:95-135. [PMID: 17854656 DOI: 10.1016/s0065-3233(07)74003-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The binding of full and partial agonist ligands (L) to G protein-coupled receptors (GPCRs) initiates the formation of ternary complexes with G proteins [ligand-receptor-G protein (LRG) complexes]. Cyclic ternary complex models are required to account for the thermodynamically plausible complexes. It has recently become possible to assemble solubilized formyl peptide receptor (FPR) and beta(2)-adrenergic receptor (beta(2)AR) ternary complexes for flow cytometric bead-based assays. In these systems, soluble ternary complex formation of the receptors with G proteins allows direct quantitative measurements which can be analyzed in terms of three-dimensional concentrations (molarity). In contrast to the difficulty of analyzing comparable measurements in two-dimensional membrane systems, the output of these flow cytometric experiments can be analyzed via ternary complex simulations in which all of the parameters can be estimated. An outcome from such analysis yielded lower affinity for soluble ternary complex assembly by partial agonists compared with full agonists for the beta(2)AR. In the four-sided ternary complex model, this behavior is consistent with distinct ligand-induced conformational states for full and partial agonists. Rapid mix flow cytometry is used to analyze the subsecond dynamics of guanine nucleotide-mediated ternary complex disassembly. The modular breakup of ternary complex components is highlighted by the finding that the fastest step involves the departure of the ligand-activated GPCR from the intact G protein heterotrimer. The data also show that, under these experimental conditions, G protein subunit dissociation does not occur within the time frame relevant to signaling. The data and concepts are discussed in the context of a review of current literature on signaling mechanism based on structural and spectroscopic (FRET) studies of ternary complex components.
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Affiliation(s)
- Tione Buranda
- Department of Pathology and Cancer Center, University of New Mexico Health Science Center, Albuquerque, New Mexico 87131, USA
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Ning Y, Buranda T, Hudson LG. Activated epidermal growth factor receptor induces integrin alpha2 internalization via caveolae/raft-dependent endocytic pathway. J Biol Chem 2006; 282:6380-7. [PMID: 17179151 DOI: 10.1074/jbc.m610915200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [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] [Indexed: 11/06/2022] Open
Abstract
Elevated expression or activity of the epidermal growth factor (EGF) receptor is common in ovarian cancer and is associated with poor patient prognosis. Our previous studies demonstrated that expression of the constitutively active mutant form of the EGF receptor (EGFRvIII) in ovarian cancer cells led to reduction in integrin alpha2 surface expression, defects in cell spreading, and disruption of focal adhesions. Inhibition of EGFRvIII catalytic activity reversed the response, suggesting that EGF receptor activation regulates integrin alpha2. In this study we found that EGF treatment resulted in a transient loss of integrin alpha2 from the cell surface. Before EGF stimulation, integrin alpha2 and EGF receptors were associated based on biochemical and immuno-colocalization approaches. After EGF treatment, EGF receptor and integrin alpha2 were internalized and segregated into different compartments. Integrin alpha2, but not EGF receptor, was associated with caveolin-1 and GM1 (Gal_1,3GalNAc_1,4(Neu5Ac-_ 2,3)Gal_1,4Glc_1,1-ceramide) gangliosides, suggesting caveolae-mediated endocytosis. Moreover, integrin alpha2 was subsequently targeted to the Golgi apparatus and the endoplasmic reticulum. Together, these findings demonstrate that activated EGF receptor transiently modulates integrin alpha2 cell surface expression and stimulates integrin alpha2 trafficking via caveolae/raft-mediated endocytosis, representing a novel mechanism by which the EGF receptor may regulate integrin-mediated cell behavior.
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Affiliation(s)
- Yan Ning
- College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Piyasena ME, Buranda T, Wu Y, Huang J, Sklar LA, Lopez GP. Near-simultaneous and real-time detection of multiple analytes in affinity microcolumns. Anal Chem 2006; 76:6266-73. [PMID: 15516117 DOI: 10.1021/ac049260f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [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: 11/30/2022]
Abstract
A miniaturized immunoassay system based on beads in poly(dimethylsiloxane) microchannels for analyzing multiple analytes has been developed. The method involves real-time detection of soluble molecules binding to receptor-bearing microspheres, sequestered in affinity column format inside a microfluidic channel. Identification and quantitation of analytes occurs via direct fluorescence measurements or fluorescence resonance energy transfer. A preliminary account of this work based on single-analyte format has been published in this journal (Buranda, T.; Huang, J.; Perez-Luna, V. H.; Schreyer, B.; Sklar, L. A.; Lopez, G. P. Anal. Chem. 2002, 74, 1149-1156). We have extended the work to a multianalyte model system composed of discrete segments of beads that bear distinct receptors. Near-simultaneous and real-time detection of diverse analytes is demonstrated. The importance of this work is established in the exploration of important factors related to the design, assessment, and utility of affinity microcolumn sensors. First, beads derivatized with surface chemistry suitable for the attachment of fluorescently labeled biomolecules of interest are prepared and characterized in terms of functionality and receptor site densities by flow cytometry. Second, calibrated beads are incorporated in microfluidic channels. The analytical device that emerges replicates the basic elements of affinity chromatography with the advantages of microscale and real-time direct measurement of bound analyte on beads rather than the indirect determination from eluted sample typical of affinity chromatography. In addition, the two-compartment analysis of the assay data as demonstrated in single-analyte columns provides a template upon which the dynamics of multiple-analyte assays can be characterized using existing theoretical models and be tested experimentally. The assay can potentially detect subfemtomole quantities of protein with high signal-to-noise ratio and a large dynamic range spanning nearly 4 orders of magnitude in analyte concentration in microliter to submicroliter volumes of analyte fluid. The approach has the potential to be generalized to a host of bioaffinity assay methods including analysis of protein complexes (e.g., biomolecular indicators of diseases). Proof-of-principle analytes include FLAG peptide and carcinoembryonic antigen detected at physiologically relevant concentration levels.
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Affiliation(s)
- Menake E Piyasena
- Cancer Center and Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA
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Abstract
We describe a process for covalently linking proteins to glass microscope slides and microbeads in a manner that optimizes the reactivity of the immobilized proteins and that is suitable for high-throughput microarray and flow cytometry analysis. The method involves the diazo coupling of proteins onto activated self-assembled monolayers formed from p-aminophenyl trimethoxysilane. Proteins immobilized by this method maintained bioactivity and produced enhanced levels of protein-protein interaction, low background fluorescence, and high selectivity. The binding of immobilized proteins to their specific binding partner was analyzed quantitatively and successfully correlated with solution concentrations. Diazotized surfaces bound more efficiently to proteins containing a hexahistidine tag than those without a his-tag. Moreover, significantly higher reactivity of the immobilized his-tagged proteins was observed on diazotized surfaces than on amine-terminated surfaces. Results suggest that his-tagged proteins are immobilized by reaction of the his-tag with the diazotized surface, thus offering the possibility for preferential orientation of covalently bound proteins.
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Affiliation(s)
- Yang Wu
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA
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Abstract
BACKGROUND Rapid-mix flow cytometry has emerged as a powerful tool for mechanistic analysis of ligand binding, cell response, and molecular assembly. Although progress has come from improving sample delivery capabilities, little attention has been paid to the volumetric requirements associated with precious biological reagents. METHODS By using programmable syringes, valves, and other fluidic components, we created a modular, precisely regulated rapid-mix device for the delivery of small-volume samples to the flow cytometer. The device was tested using a bead-based assay in which the binding kinetics between native biotin and fluorescein biotin-bearing beads were characterized. RESULTS Bead suspensions and reagents paired in 35- to 45-microl aliquots were efficiently mixed by the device and delivered to the flow cytometer. Kinetic data associated with the fluorescein biotin beads were analyzed and used to calibrate the performance characteristics of the device in terms of sample delivery and mixing efficiency. CONCLUSION The rapid-mix device is capable of detecting subsecond kinetics of biological reactions using microliter volume of samples. Dimensions of the device have been minimized, and the quantitative aspects of sample delivery and analysis have been optimized. Further, the modular design has been optimized for adaptation to a variety of experimental protocols.
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Affiliation(s)
- Yang Wu
- Department of Chemical and Nuclear Engineering, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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Wu Y, Simons PC, Lopez GP, Sklar LA, Buranda T. Dynamics of fluorescence dequenching of ostrich-quenched fluorescein biotin: A multifunctional quantitative assay for biotin. Anal Biochem 2005; 342:221-8. [PMID: 15913533 DOI: 10.1016/j.ab.2005.03.046] [Citation(s) in RCA: 12] [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: 01/21/2005] [Revised: 03/02/2005] [Accepted: 03/28/2005] [Indexed: 11/23/2022]
Abstract
We describe a simple and rapid quantitative assay for biotin and biotin conjugates. The assay is based on the kinetic analysis of the enhancement of fluorescence of streptavidin/fluorescein biotin complexes in the presence of biotin. The kinetic response of fluorescence enhancement is proportional to the concentration of biotin. Standard calibration curves based on the kinetic response are obtained and detection limits of approximately 10(-9)M are established. Because the assay is amenable for use in small volumes of 5-50 microL or bead-based assays, the detection limits can be extended to the femtomole range. Since the assay depends on kinetic analysis, routine quantitation can be achieved without reference to standard curves. The dynamic aspects allow the assay to be extended to a broader range of applications including its use as an indicator of reagent mixing in laminar-flow assays carried out in microfluidic devices.
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Affiliation(s)
- Yang Wu
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
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Babbitt SE, Kiss A, Deffenbaugh AE, Chang YH, Bailly E, Erdjument-Bromage H, Tempst P, Buranda T, Sklar LA, Baumler J, Gogol E, Skowyra D. ATP hydrolysis-dependent disassembly of the 26S proteasome is part of the catalytic cycle. Cell 2005; 121:553-565. [PMID: 15907469 DOI: 10.1016/j.cell.2005.03.028] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [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] [Received: 09/15/2004] [Revised: 01/03/2005] [Accepted: 03/18/2005] [Indexed: 10/25/2022]
Abstract
ATP hydrolysis is required for degradation of polyubiquitinated proteins by the 26S proteasome but is thought to play no role in proteasomal stability during the catalytic cycle. In contrast to this view, we report that ATP hydrolysis triggers rapid dissociation of the 19S regulatory particles from immunopurified 26S complexes in a manner coincident with release of the bulk of proteasome-interacting proteins. Strikingly, this mechanism leads to quantitative disassembly of the 19S into subcomplexes and free Rpn10, the polyubiquitin binding subunit. Biochemical reconstitution with purified Sic1, a prototype substrate of the Cdc34/SCF ubiquitin ligase, suggests that substrate degradation is essential for triggering the ATP hydrolysis-dependent dissociation and disassembly of the 19S and that this mechanism leads to release of degradation products. This is the first demonstration that a controlled dissociation of the 19S regulatory particles from the 26S proteasome is part of the mechanism of protein degradation.
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Affiliation(s)
- Shalon E Babbitt
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Alexi Kiss
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Andrew E Deffenbaugh
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Yie-Hwa Chang
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Eric Bailly
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires-Centre National de la Recherche Scientifique, Marseille Cedex 20, France
| | | | - Paul Tempst
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021
| | - Tione Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131
| | - Larry A Sklar
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131
| | - Jennifer Baumler
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Edward Gogol
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110
| | - Dorota Skowyra
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104.
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37
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Larson RS, Davis T, Bologa C, Semenuk G, Vijayan S, Li Y, Oprea T, Chigaev A, Buranda T, Wagner CR, Sklar LA. Dissociation of I domain and global conformational changes in LFA-1: refinement of small molecule-I domain structure-activity relationships. Biochemistry 2005; 44:4322-31. [PMID: 15766261 DOI: 10.1021/bi048187k] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
LFA-1 (alphalbeta2) is constitutively expressed on leukocytes, but its activity is rapidly regulated. This rapid activation has been proposed to be associated with conformation changes in the inserted ("I") domain within the headpiece of LFA-1 as well as conversion of the molecules from bent to extended forms. To study these molecular changes as they relate to affinity regulation of LFA-1, we developed and synthesized a fluorescent derivative of BIRT-377 [Kelly et al. (2001) J. Immunol.] to examine changes in LFA-1 affinity in a flow cytometer with live cells. BIRT-377 binds to the ligand-binding or "I" domain of LFA-1. Structure-activity relationships studies indicated that an aminoalkyl group could be added to the central hydantoin group without significantly affecting binding. Using this modified derivative [1-(N-fluoresceinylthioureidobutyl)-[5R]-(4-bromobenzyl)-3-(3,5-dichlorophenyl)-5-methyl-imidazolidine-2,4-dione (FBABIRT)], we analyzed the affinity of FBABIRT binding to LFA-1 on live cells. The binding affinity increases, and the dissociation rate decreases with divalent cation (Mn(2+)) stimulation. We then used FBABIRT with fluorescent resonance energy transfer (FRET) to show that LFA-1 changes its height relative to the cell surface when cells were treated with dithiothreitol (DTT) but not Mn(2+). Competition assays among FBABIRT and BIRT derivatives defined structure-affinity relationships that refine the current model of BIRT-377 binding to the I domain. Our data supports the model in which BIRT-377 binds to the I domain and stabilizes the bent structure of LFA-1, while divalent cation activation results in a small conformational change in the I domain without significant extension of LFA-1. DTT, in contrast, induces a conversion to the extended form of LFA-1 in the presence of BIRT-377 on live cells. The structure-activity studies suggest that BIRT-377 is a fully optimized inhibitor.
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Affiliation(s)
- Richard S Larson
- Department of Pathology, University of New Mexico, and Cancer Research and Treatment Center, Albuquerque, New Mexico 87131-5301, USA.
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38
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Burns AR, Frankel DJ, Buranda T. Local mobility in lipid domains of supported bilayers characterized by atomic force microscopy and fluorescence correlation spectroscopy. Biophys J 2005; 89:1081-93. [PMID: 15879469 PMCID: PMC1366593 DOI: 10.1529/biophysj.105.060327] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [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: 11/18/2022] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is used to examine mobility of labeled probes at specific sites in supported bilayers consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid domains in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). Those sites are mapped beforehand with simultaneous atomic force microscopy and submicron confocal fluorescence imaging, allowing characterization of probe partitioning between gel DPPC and disordered liquid DOPC domains with corresponding topography of domain structure. We thus examine the relative partitioning and mobility in gel and disordered liquid phases for headgroup- and tailgroup-labeled GM1 ganglioside probes and for headgroup- and tailgroup-labeled phospholipid probes. For the GM1 probes, large differences in mobility between fluid and gel domains are observed; whereas unexpected mobility is observed in submicron gel domains for the phospholipid probes. We attribute the latter to domain heterogeneities that could be induced by the probe. Furthermore, fits to the FCS data for the phospholipid probes in the DOPC fluid phase require two components (fast and slow). Although proximity to the glass substrate may be a factor, local distortion of the probe by the fluorophore could also be important. Overall, we observe nonideal aspects of phospholipid probe mobility and partitioning that may not be restricted to supported bilayers.
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Affiliation(s)
- A R Burns
- Biomolecular Materials and Interfaces Department, MS 1413 Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
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39
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Bartsch JW, Tran HD, Waller A, Mammoli AA, Buranda T, Sklar LA, Edwards BS. An investigation of liquid carryover and sample residual for a high-throughput flow cytometer sample delivery system. Anal Chem 2005; 76:3810-7. [PMID: 15228359 DOI: 10.1021/ac049870f] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [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: 11/29/2022]
Abstract
The phenomenon of intersample contamination in air-segmented continuous-flow assays has been studied for many years, and new uses are being found for these sampling techniques every day. One application that has been developed recently employs a flow cytometer to conduct high-throughput screening assays of biological compounds. We have explored the sources of intersample contamination in the system and shown how methods developed previously can be applied to describe these phenomena. Using a simple model, we were able to accurately measure liquid film thickness in the sample tubing and demonstrate the effects of intersample contamination in a flow cytometer assay. Also, measures have been taken to reduce the level of intersample contamination in cytometric screening assays, helping to make the system a more viable tool for drug screening applications.
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Affiliation(s)
- Joseph W Bartsch
- Department of Mechanical Engineering, University of New Mexico, Albuquerque, NM 87131, USA.
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40
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Xue M, Vines CM, Buranda T, Cimino DF, Bennett TA, Prossnitz ER. N-formyl peptide receptors cluster in an active raft-associated state prior to phosphorylation. J Biol Chem 2004; 279:45175-84. [PMID: 15302864 DOI: 10.1074/jbc.m407053200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [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] [Indexed: 11/06/2022] Open
Abstract
In response to ligand binding, G protein-coupled receptors undergo phosphorylation and activate cellular internalization machinery. An important component of this process is the concentration of receptors into clusters on the plasma membrane. Aside from organizing the receptor in anticipation of internalization, little is known of the function of ligand-mediated G protein-coupled receptor clustering, which has traditionally been thought of as being a phosphorylation-dependent event prior to receptor internalization. We now report that following receptor activation, the N-formyl peptide receptor (FPR) forms distinct membrane clusters prior to its association with arrestin. To determine whether this clustering is dependent upon receptor phosphorylation, we used a mutant form of the FPR, DeltaST-FPR, which lacks all phosphorylation sites in the carboxyl-terminal domain. We found that activation of the signaling-competent DeltaST-FPR resulted in rapid receptor clustering on the plasma membrane independent of Gi protein activation. This clustering required receptor activation since the D71A mutant receptor, which binds ligand but is incapable of transitioning to an active state, failed to induce receptor clustering. Furthermore we demonstrated that FPR-mediated clustering and signaling were cholesterol-dependent processes, suggesting that translocation of the active receptor to lipid rafts may be required for maximal signaling activity. Finally we showed that FPR stimulation in the absence of receptor phosphorylation resulted in translocation of FPR to GM1-rich clusters. Our results demonstrate for the first time that formation of a clustered activated receptor state precedes receptor phosphorylation, arrestin binding, and internalization.
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Affiliation(s)
- Mei Xue
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque 87131, USA
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41
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Abstract
Integrins are cell adhesion receptors, expressed on every cell type, that have been postulated to undergo conformational changes upon activation. Here, different affinity states were generated by exposing alpha4-integrins to divalent ions or by inside-out activation using a chemokine receptor. We probed the dynamic structural transformation of the integrin on live cells using fluorescence resonance energy transfer (FRET) between a peptide donor, which specifically binds to the alpha4-integrin, and octadecyl rhodamine B acceptors incorporated into the plasma membrane. We analyzed the data using a model that describes FRET between a random distribution of donors and acceptors in an infinite plane. The distance of closest approach was found to vary with the affinity of the integrin. The change in distance of closest approach was approximately 50 A between resting and Mn2+ activated receptors and approximately 25 A after chemokine activation. We used confocal microscopy to probe the lateral organization of donors and acceptors subsequent to integrin activation. Taken together, FRET and confocal results suggest that changes in FRET efficiencies are primarily due to the vertical extension of the integrin. The coordination between the extension of alpha4-integrin and its affinity provides a mechanism for Dembo's catch-bond concept.
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Affiliation(s)
- Alexandre Chigaev
- Department of Pathology and Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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42
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Chigaev A, Zwartz GJ, Buranda T, Edwards BS, Prossnitz ER, Sklar LA. Conformational regulation of alpha 4 beta 1-integrin affinity by reducing agents. "Inside-out" signaling is independent of and additive to reduction-regulated integrin activation. J Biol Chem 2004; 279:32435-43. [PMID: 15166232 DOI: 10.1074/jbc.m404387200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [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] [Indexed: 01/12/2023] Open
Abstract
The alpha(4)beta(1)-integrin (very late antigen-4 (VLA-4), CD49d/CD29) is an adhesion receptor involved in the interaction of lymphocytes, dendritic cells, and stem cells with the extracellular matrix and endothelial cells. This and other integrins have the ability to regulate their affinity for ligands through a process termed "inside-out" signaling that affects cell adhesion avidity. Several mechanisms are known to regulate integrin affinity and conformation: conformational changes induced by separation of the C-terminal tails, divalent ions, and reducing agents. Recently, we described a fluorescent LDV-containing small molecule that was used to monitor VLA-4 affinity changes in live cells (Chigaev, A., Blenc, A. M., Braaten, J. V., Kumaraswamy, N., Kepley, C. L., Andrews, R. P., Oliver, J. M., Edwards, B. S., Prossnitz, E. R., Larson, R. S., and Sklar, L. A. (2001) J. Biol. Chem. 276, 48670-48678). Using the same molecule, we also developed a fluorescence resonance energy transfer-based assay to probe the "switchblade-like" opening of VLA-4 upon activation. Here, we investigated the effect of reducing agents on the affinity and conformational state of the VLA-4 integrin simultaneously with cell activation initiated by inside-out signaling through G protein-coupled receptors or Mn(2+) in live cells in real time. We found that reducing agents (dithiothreitol and 2,3-dimercapto-1-propanesulfonic acid) induced multiple states of high affinity of VLA-4, where the affinity change was accompanied by an extension of the integrin molecule. Bacitracin, an inhibitor of the reductive function of the plasma membrane, diminished the effect of dithiothreitol, but had no effect on inside-out signaling. Based on this result and differences in the kinetics of integrin activation, we conclude that conformational activation of VLA-4 by inside-out signaling is independent of and additive to reduction-regulated integrin activation.
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Affiliation(s)
- Alexandre Chigaev
- Department of Pathology and the Cancer Center, University of New Mexico Health Sciences Center, Albequerque, 87131, USA
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43
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Simons PC, Shi M, Foutz T, Cimino DF, Lewis J, Buranda T, Lim WK, Neubig RR, McIntire WE, Garrison J, Prossnitz E, Sklar LA. Ligand-receptor-G-protein molecular assemblies on beads for mechanistic studies and screening by flow cytometry. Mol Pharmacol 2003; 64:1227-38. [PMID: 14573773 DOI: 10.1124/mol.64.5.1227] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [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] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors form a ternary complex of ligand, receptor, and G protein heterotrimer (LRG) during signal transduction from the outside to the inside of a cell. Our goal was to develop a homogeneous, small-volume, bead-based approach compatible with high-throughput flow cytometry that would allow evaluation of G protein coupled receptor molecular assemblies. Dextran beads were derivatized to carry chelated nickel to bind hexahistidine-tagged green fluorescent protein (GFP) and hexahistidine-tagged G proteins. Ternary complexes were assembled on these beads using fluorescent ligand with wild-type receptor or a receptor-Gialpha2 fusion protein, and with a nonfluorescent ligand and receptor-GFP fusion protein. Streptavidin-coated polystyrene beads used biotinylated anti-FLAG antibodies to bind FLAG-tagged G proteins for ternary complex assembly. Validation was achieved by showing time and concentration dependence of ternary complex formation. Affinity measurements of ligand for receptor on particles, of the ligand-receptor complex for G protein on the particles, and receptor-Gialpha2 fusion protein for Gbetagamma, were consistent with comparable assemblies in detergent suspension. Performance was assessed in applications representing the potential of these assemblies for ternary complex mechanisms. We showed the relationship for a family of ligands between LR and LRG affinity and characterized the affinity of both the wild-type and GFP fusion receptors with G protein. We also showed the potential of kinetic measurements to allow observation of individual steps of GTP-induced ternary complex disassembly and discriminated a fast step caused by RG disassembly compared with the slower step of Galphabetagamma disassembly.
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Affiliation(s)
- Peter C Simons
- Department of Pathology and Cancer Center, University of New Mexico HSC, Albuquerque, NM 87131, USA
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44
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Deffenbaugh AE, Scaglione KM, Zhang L, Moore JM, Buranda T, Sklar LA, Skowyra D. Release of ubiquitin-charged Cdc34-S - Ub from the RING domain is essential for ubiquitination of the SCF(Cdc4)-bound substrate Sic1. Cell 2003; 114:611-22. [PMID: 13678584 DOI: 10.1016/s0092-8674(03)00641-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [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: 10/26/2022]
Abstract
The S. cerevisiae SCF(Cdc4) is a prototype of RING-type SCF E3s, which recruit substrates for polyubiquitination by the Cdc34 ubiquitin-conjugating enzyme. Current models propose that Cdc34 ubiquitinates the substrate while remaining bound to the RING domain. In contrast, we found that the formation of a ubiquitin thiol ester regulates the Cdc34/SCF(Cdc4) binding equilibrium by increasing the dissociation rate constant, with only a minor effect on the association rate. By using a F72VCdc34 mutant with increased affinity for the RING domain, we demonstrate that release of ubiquitin-charged Cdc34-S - Ub from the RING is essential for ubiquitination of the SCF(Cdc4)-bound substrate Sic1. Release of ubiquitin-charged E2 from E3 prior to ubiquitin transfer is a previously unrecognized step in ubiquitination, which can explain both the modification of multiple lysines on the recruited substrate and the extension of polyubiquitin chains. We discuss implications of this finding for function of other ubiquitin ligases.
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Affiliation(s)
- Andrew E Deffenbaugh
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO 63104, USA
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45
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Buranda T, Lei Y, Endicott JF. Photoinduced electron transfer in multimetal complexes. Observations on electronically forbidden back electron transfers. J Am Chem Soc 2002. [DOI: 10.1021/ja00043a047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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46
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Lei Y, Buranda T, Endicott JF. Photoinduced energy transfer in multinuclear transition-metal complexes. Reversible and irreversible energy flow between charge-transfer and ligand field excited states of cyanide-bridged ruthenium(II)-chromium(III) and ruthenium(II)-rhodium(III) complexes. J Am Chem Soc 2002. [DOI: 10.1021/ja00180a025] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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47
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Lessard RB, Heeg MJ, Buranda T, Perkovic MW, Schwarz CL, Yang R, Endicott JF. Stereochemical alterations of 2E chromium(III) excited-state behavior in dicyanotetraazacyclotetradecane complexes. Ground-state x-ray crystal structures, photophysical behavior, and molecular mechanics simulations of stereochemical effects. Inorg Chem 2002. [DOI: 10.1021/ic00040a019] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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48
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Buranda T, Huang J, Perez-Luna VH, Schreyer B, Sklar LA, Lopez GP. Biomolecular recognition on well-characterized beads packed in microfluidic channels. Anal Chem 2002; 74:1149-56. [PMID: 11924977 DOI: 10.1021/ac0109624] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [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] [Indexed: 11/28/2022]
Abstract
We describe a new approach for the analysis of biomolecular recognition in microfluidic channels. The method involves real-time detection of soluble molecules binding to receptor-bearing microspheres, sequestered in affinity column format inside a microfluidic channel. Identification and quantitation of analytes occurs via direct fluorescence measurements or fluorescence resonance energy transfer (FRET). We establish a model system that detects the FLAG epitope. The assay can potentially detect subfemtomole quantities of antibody with a high signal-to-noise ratio and a large dynamic range spanning nearly 4 orders of magnitude in analyte concentration in microliter-to-submicroliter volumes of analyte fluid. Kinetic and equilibrium constants for the reaction of this receptor-ligand pair are obtained through modeling of kinetic responses of the affinity microcolumn and are consistent with those obtained by flow cytometry. Because of the correlation between kinetic and equilibrium data obtained for the microcolumns, quantitative analysis can be done prior to the steady-state end point of the recognition reaction. This method has the promise of combining the utility of affinity chromatography with the advantage of direct, quantitative, and real-time analysis and the cost-effectiveness of microanalytical devices. The approach has the potential to be generalized to a host of bioaffinity assay methods including analysis of protein complexes and molecular assembly and microsystem-based multianalyte determinations.
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Affiliation(s)
- Tione Buranda
- Cancer Center and Department of Pathology, University of New Mexico School of Medicine, NSF Center for Micro-Engineered Materials, and Chemical and Nuclear Engineering, Albuquerque, USA.
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49
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Jackson WC, Kuckuck F, Edwards BS, Mammoli A, Gallegos CM, Lopez GP, Buranda T, Sklar LA. Mixing small volumes for continuous high-throughput flow cytometry: performance of a mixing Y and peristaltic sample delivery. Cytometry 2002; 47:183-91. [PMID: 11891723 DOI: 10.1002/cyto.10067] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Online mixing for continuous high-throughput flow cytometry has not been previously described. A simple, general high-throughput method for mixing and delivery of submicroliter volumes in laminar flow at low Reynolds numbers would be widely useful. MATERIALS AND METHODS We describe a micromixing approach that is compatible with commercial autosamplers, flow cytometry, and other detection schemes that require mixing of components that have been introduced into laminar flow. The scheme is based on a previous approach to high-throughput flow cytometry (HyperCyt, Kuckuck et al.: Cytometry 44:83-90, 2001). We showed that samples from multiwell plates that have been picked up by an autosampler can be separated during delivery by the small air bubbles introduced during the transit of the autosampler probe from well to well. Here, a particle sample flowing continuously is brought together in a Y with reagent samples from wells, which have been separated by bubbles. RESULTS In the effluent stream, the particles and reagents are mixed, most likely as a result of peristaltic action, and reagents from individual wells can be resolved. The sample volumes that can be mixed with this technology are submicroliter in volume, and samples can be mixed at rates up to at least 100/samples per minute. With the current device, carryover between samples can be eliminated if the mixing system is flushed with several volumes of buffer. The anticipated throughput for screening is expected to be at least 20 samples per minute. CONCLUSIONS The high-throughput approach and peristaltic mixing in HyperCytTM serve to integrate autosamplers with submicroliter detection volumes for analysis in flow cytometry or in microfluidic channels.
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Affiliation(s)
- W Coyt Jackson
- Department of Pathology and Cancer Research Facility, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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50
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Pérez-Luna VH, Yang S, Rabinovich EM, Buranda T, Sklar LA, Hampton PD, López GP. Fluorescence biosensing strategy based on energy transfer between fluorescently labeled receptors and a metallic surface. Biosens Bioelectron 2002; 17:71-8. [PMID: 11742737 DOI: 10.1016/s0956-5663(01)00260-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [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: 11/19/2022]
Abstract
A new fluorescence-based biosensor is presented. The biosensing scheme is based on the fact that a fluorophore in close proximity to a metal film (<100 A) experiences strong quenching of fluorescence and a dramatic reduction in the lifetime of the excited state. By immobilizing the analyte of interest (or a structural analog of the analyte) to a metal surface and exposing it to a labeled receptor (e.g. antibody), the fluorescence of the labeled receptor becomes quenched upon binding because of the close proximity to the metal. Upon exposure to free analyte, the labeled receptor dissociates from the surface and diffuses into the bulk of the solution. This increases its separation from the metal and an increase of fluorescence intensity and/or lifetime of the excited state is observed that indicates the presence of the soluble analyte. By enclosing this system within a small volume with a semipermeable membrane, a reversible device is obtained. We demonstrate this scheme using a biotinylated self-assembled monolayer (SAM) on gold as our surface immobilized analyte analog, fluorescently labeled anti-biotin as a receptor, and a solution of biotin in PBS as a model analyte. This scheme could easily be extended to transduce a wide variety of protein-ligand interactions and other biorecognition phenomena (e.g. DNA hybridization) that result in changes in the architecture of surface immobilized biomolecules such that a change in the separation distance between fluorophores and the metal film is obtained.
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Affiliation(s)
- Víctor H Pérez-Luna
- Department of Chemical and Nuclear Engineering, The University of New Mexico, 209 Farris Engineering Center, Albuquerque, NM 87131, USA
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