1
|
Fields FR, Manzo G, Hind CK, Janardhanan J, Foik IP, Carmo Silva PD, Balsara RD, Clifford M, Vu HM, Ross JN, Kalwajtys VR, Gonzalez AJ, Bui TT, Ploplis VA, Castellino FJ, Siryaporn A, Chang M, Sutton JM, Mason AJ, Lee S. Synthetic Antimicrobial Peptide Tuning Permits Membrane Disruption and Interpeptide Synergy. ACS Pharmacol Transl Sci 2020; 3:418-424. [PMID: 32566907 DOI: 10.1021/acsptsci.0c00001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Indexed: 12/19/2022]
Abstract
The ribosomally produced antimicrobial peptides of bacteria (bacteriocins) represent an unexplored source of membrane-active antibiotics. We designed a library of linear peptides from a circular bacteriocin and show that pore-formation dynamics in bacterial membranes are tunable via selective amino acid substitution. We observed antibacterial interpeptide synergy indicating that fundamentally altering interactions with the membrane enables synergy. Our findings suggest an approach for engineering pore-formation through rational peptide design and increasing the utility of novel antimicrobial peptides by exploiting synergy.
Collapse
Affiliation(s)
- Francisco R Fields
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Chemistry Biology Biochemistry Interface, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Giorgia Manzo
- Institue of Pharmaceutical Science, School of Cancer & Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Charlotte K Hind
- Technology Development Group, National Infection Service, Public Health England, Salisbury SP4 0JG, U.K
| | - Jeshina Janardhanan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Ilona P Foik
- Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, United States
| | - Phoebe Do Carmo Silva
- Technology Development Group, National Infection Service, Public Health England, Salisbury SP4 0JG, U.K
| | - Rashna D Balsara
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.,W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Melanie Clifford
- Technology Development Group, National Infection Service, Public Health England, Salisbury SP4 0JG, U.K
| | - Henry M Vu
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States.,W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jessica N Ross
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Veronica R Kalwajtys
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Alejandro J Gonzalez
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Tam T Bui
- Centre for Biomolecular Spectroscopy and Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, London SE1 1UL, United Kingdom
| | - Victoria A Ploplis
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.,W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Francis J Castellino
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.,W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Albert Siryaporn
- Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, United States.,Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California 92697, United States
| | - Mayland Chang
- Chemistry Biology Biochemistry Interface, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - J Mark Sutton
- Technology Development Group, National Infection Service, Public Health England, Salisbury SP4 0JG, U.K
| | - A James Mason
- Institue of Pharmaceutical Science, School of Cancer & Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Shaun Lee
- Department of Biology, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Chemistry Biology Biochemistry Interface, University of Notre Dame, Notre Dame, Indiana 46556, United States
| |
Collapse
|
2
|
Qiu C, Yuan Y, Zajicek J, Liang Z, Balsara RD, Brito-Robionson T, Lee SW, Ploplis VA, Castellino FJ. Contributions of different modules of the plasminogen-binding Streptococcus pyogenes M-protein that mediate its functional dimerization. J Struct Biol 2018; 204:151-164. [PMID: 30071314 PMCID: PMC6544907 DOI: 10.1016/j.jsb.2018.07.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/26/2018] [Accepted: 07/28/2018] [Indexed: 10/28/2022]
Abstract
Group A Streptococcus pyogenes (GAS) is a causative agent of pharyngeal and dermal infections in humans. A major virulence determinant of GAS is its dimeric signature fibrillar M-protein (M-Prt), which is evolutionarily designed in modules, ranging from a hypervariable extracellular N-terminal region to a progressively more highly conserved C-terminus that is covalently anchored to the cell wall. Of the >250 GAS isolates classified, only the subset of skin-trophic Pattern D strains expresses a specific serotype of M-Prt, PAM, that directly binds to host human plasminogen (hPg) via its extracellular NH2-terminal variable A-domain region. This interaction allows these GAS strains to accumulate components of the host fibrinolytic system on their surfaces to serve extracellular functions. While structure-function studies have been accomplished on M-Prts from Pattern A-C GAS isolates with different direct ligand binding properties compared to PAM, much less is known regarding the structure-function relationships of PAM-type M-Prts, particularly their dimerization determinants. To examine these questions, PAMs from seven GAS strains with sequence variations in the NH2-terminal ligand binding domains, as well as truncated versions of PAM, were designed and studied. The results from bioinformatic and biophysical analyses show that the different domains of PAM are disparately engaged in dimerization. From these data, we propose an experimentally-based model for PAM secondary and quaternary structures that is highly dependent on the conserved helical C-terminal C-D-domains. In addition, while the N-terminal regions of PAMs are variable in sequence, the binding properties of hPg and its activated product, plasmin, to the A-domain, remain intact.
Collapse
Affiliation(s)
- Cunjia Qiu
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Yue Yuan
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Jaroslav Zajicek
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Zhong Liang
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Rashna D Balsara
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Teresa Brito-Robionson
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Shaun W Lee
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Victoria A Ploplis
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Francis J Castellino
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States.
| |
Collapse
|
3
|
Fields FR, Carothers KE, Balsara RD, Ploplis VA, Castellino FJ, Lee SW. Rational design of syn-safencin, a novel linear antimicrobial peptide derived from the circular bacteriocin safencin AS-48. J Antibiot (Tokyo) 2018; 71:592-600. [DOI: 10.1038/s41429-018-0032-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 12/13/2017] [Accepted: 01/03/2018] [Indexed: 12/12/2022]
|
4
|
Abstract
SummaryPlasminogen activator inhibitor type-1 (PAI-1) is a multi-functional protein. It is a fast-acting inhibitor of plasminogen activators; urokinase-plasminogen activator and tissue type plasminogen activator, and also plays an important role in regulating cell proliferation, adhesion, migration, and signal transduction pathways.These biological events are important processes during angiogenesis and restenosis. PAI-1 has been shown to regulate proliferation, migration, and apoptosis of vascular smooth muscle cells and endothelial cells.The ability of PAI-1 to regulate cellular proliferation and migration has been attributed to its ability to control plasmin production, modify signaling pathways, and its inherent multifactorial ability to bind to vitronectin and lipoprotein receptor-related protein.However,the mechanism by which PAI-1 regulates the apoptotic pathway is not well understood. Evidence from the literature suggests that PAI-1 or its deficiency alters key signalling pathways, such as the PI3-k/Akt and the Jak/STAT pathways, and is involved in maintaining endothelial cell integrity thereby regulating cell death. Other investigators have demonstrated that PAI-1 directly binds to caspases as a mechanism of PAI-1-mediated cellular apoptosis. Moreover, results from studies assessing the role of PAI-1 in apoptosis have suggested that PAI-1 can exert pathogenic or protective effects, which may be related to the disease model or type of injury employed.
Collapse
|
5
|
Yuan Y, Balsara RD, Zajicek J, Kunda S, Castellino FJ. Discerning the Role of the Hydroxyproline Residue in the Structure of Conantokin Rl-B and Its Role in GluN2B Subunit-Selective Antagonistic Activity toward N-Methyl-d-Aspartate Receptors. Biochemistry 2016; 55:7112-7122. [DOI: 10.1021/acs.biochem.6b00962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Yue Yuan
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Rashna D. Balsara
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jaroslav Zajicek
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shailaja Kunda
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Francis J. Castellino
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| |
Collapse
|
6
|
Cheriyan J, Balsara RD, Hansen KB, Castellino FJ. Pharmacology of triheteromeric N-Methyl-D-Aspartate Receptors. Neurosci Lett 2016; 617:240-6. [PMID: 26917100 DOI: 10.1016/j.neulet.2016.02.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [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: 12/09/2015] [Revised: 02/02/2016] [Accepted: 02/16/2016] [Indexed: 01/08/2023]
Abstract
The N-Methyl-D-Aspartate Receptors (NMDARs) are heteromeric cation channels involved in learning, memory, and synaptic plasticity, and their dysregulation leads to various neurodegenerative disorders. Recent evidence has shown that apart from the GluN1/GluN2A and GluN1/GluN2B diheteromeric ion channels, the NMDAR also exists as a GluN1/GluN2A/GluN2B triheteromeric channel that occupies the majority of the synaptic space. These GluN1/GluN2A/GluN2B triheteromers exhibit pharmacological and electrophysiological properties that are distinct from the GluN1/GluN2A and GluN1/GluN2B diheteromeric subtypes. However, these receptors have not been characterized with regards to their inhibition by conantokins, as well as their allosteric modulation by polyamines and extracellular protons. Here, we show that the GluN1/GluN2A/GluN2B triheteromeric channels showed less sensitivity to GluN2B-specific conantokin (con)-G and con-RlB, and subunit non-specific con-T, compared to the GluN2A-specific inhibitor TCN-201. Also, spermine modulation of GluN1/GluN2A/GluN2B triheteromers switched its nature from potentiation to inhibition in a pH dependent manner, and was 2.5-fold slower compared to the GluN1/GluN2B diheteromeric channels. Unraveling the distinctive functional attributes of the GluN1/GluN2A/GluN2B triheteromers is physiologically relevant since they form an integral part of the synapse, which will aid in understanding spermine/pH-dependent potentiation of these receptors in pathological settings.
Collapse
Affiliation(s)
- John Cheriyan
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Rashna D Balsara
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Kasper B Hansen
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, MT 59812, USA
| | - Francis J Castellino
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
| |
Collapse
|
7
|
Kunda S, Yuan Y, Balsara RD, Zajicek J, Castellino FJ. Hydroxyproline-induced Helical Disruption in Conantokin Rl-B Affects Subunit-selective Antagonistic Activities toward Ion Channels of N-Methyl-d-aspartate Receptors. J Biol Chem 2015; 290:18156-18172. [PMID: 26048991 DOI: 10.1074/jbc.m115.650341] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Indexed: 01/10/2023] Open
Abstract
Conantokins are ~20-amino acid peptides present in predatory marine snail venoms that function as allosteric antagonists of ion channels of the N-methyl-d-aspartate receptor (NMDAR). These peptides possess a high percentage of post-/co-translationally modified amino acids, particularly γ-carboxyglutamate (Gla). Appropriately spaced Gla residues allow binding of functional divalent cations, which induces end-to-end α-helices in many conantokins. A smaller number of these peptides additionally contain 4-hydroxyproline (Hyp). Hyp should prevent adoption of the metal ion-induced full α-helix, with unknown functional consequences. To address this disparity, as well as the role of Hyp in conantokins, we have solved the high resolution three-dimensional solution structure of a Gla/Hyp-containing 18-residue conantokin, conRl-B, by high field NMR spectroscopy. We show that Hyp(10) disrupts only a small region of the α-helix of the Mn(2+)·peptide complex, which displays cation-induced α-helices on each terminus of the peptide. The function of conRl-B was examined by measuring its inhibition of NMDA/Gly-mediated current through NMDAR ion channels in mouse cortical neurons. The conRl-B displays high inhibitory selectivity for subclasses of NMDARs that contain the functionally important GluN2B subunit. Replacement of Hyp(10) with N(8)Q results in a Mg(2+)-complexed end-to-end α-helix, accompanied by attenuation of NMDAR inhibitory activity. However, replacement of Hyp(10) with Pro(10) allowed the resulting peptide to retain its inhibitory property but diminished its GluN2B specificity. Thus, these modified amino acids, in specific peptide backbones, play critical roles in their subunit-selective inhibition of NMDAR ion channels, a finding that can be employed to design NMDAR antagonists that function at ion channels of distinct NMDAR subclasses.
Collapse
Affiliation(s)
- Shailaja Kunda
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Yue Yuan
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Rashna D Balsara
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Jaroslav Zajicek
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Francis J Castellino
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556.
| |
Collapse
|
8
|
Cheriyan J, Mezes C, Zhou N, Balsara RD, Castellino FJ. Heteromerization of ligand binding domains of N-methyl-D-aspartate receptor requires both coagonists, L-glutamate and glycine. Biochemistry 2015; 54:787-94. [PMID: 25544544 PMCID: PMC4310633 DOI: 10.1021/bi501437s] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMDA receptors (NMDAR) are voltage- and glutamate-gated heteromeric ion channels found at excitatory neuronal synapses, the functions of which are to mediate the mechanisms of brain plasticity and, thereby, its higher order functions. In addition to Glu, the activation of these heteromeric receptors requires Gly or d-Ser as a coagonist. However, it is not fully known as to why coagonism is required for the opening of NMDAR ion channels. We show herein that the ligand binding domains (LBD) of the GluN1 and GluN2A subunits of the NMDAR heterodimerize only when both coagonists, Glu and Gly/d-Ser, bind to their respective sites on GluN2 and GluN1. In the agonist-free state, these domains form homomeric interactions, which are disrupted by binding of their respective agonists. Also, in a heteromer formed by the LBDs, GluN2A is more sensitized to bind Glu, while the affinity of Gly for GluN1 remains unchanged. We thus provide direct evidence to show that coagonism is necessary for heteromeric pairing of LBDs, which is an essential step in forming functional ion channels in NMDARs.
Collapse
Affiliation(s)
- John Cheriyan
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | | | | | | | | |
Collapse
|
9
|
Balsara RD, Chapman SE, Sander IM, Donahue DL, Liepert L, Castellino FJ, Leevy WM. Non-invasive imaging and analysis of cerebral ischemia in living rats using positron emission tomography with 18F-FDG. J Vis Exp 2014. [PMID: 25590998 PMCID: PMC4354491 DOI: 10.3791/51495] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients2, which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as 18F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions4. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.
Collapse
Affiliation(s)
- Rashna D Balsara
- W. M. Keck Center for Transgene Research, University of Notre Dame; Department of Chemistry and Biochemistry, University of Notre Dame
| | - Sarah E Chapman
- Notre Dame Integrated Imaging Facility, University of Notre Dame
| | - Ian M Sander
- Department of Biological Sciences, University of Notre Dame
| | | | - Lucas Liepert
- Department of Biological Sciences, University of Notre Dame
| | - Francis J Castellino
- W. M. Keck Center for Transgene Research, University of Notre Dame; Department of Chemistry and Biochemistry, University of Notre Dame
| | - W Matthew Leevy
- Notre Dame Integrated Imaging Facility, University of Notre Dame; Department of Biological Sciences, University of Notre Dame; Harper Cancer Research Institute, University of Notre Dame;
| |
Collapse
|
10
|
Huang L, Balsara RD, Castellino FJ. Synthetic conantokin peptides potently inhibit N-methyl-D-aspartate receptor-mediated currents of retinal ganglion cells. J Neurosci Res 2014; 92:1767-74. [PMID: 25043917 DOI: 10.1002/jnr.23447] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/12/2014] [Accepted: 06/01/2014] [Indexed: 01/16/2023]
Abstract
Retinal ganglion cells (RGCs), which are the sole output neurons of the retina, express N-methyl-D-aspartate receptors (NMDARs), rendering these cells susceptible to glutamate excitotoxicity, with implications for loss of normal RGC excitatory responses in disorders such as glaucoma and diabetic retinopathy. Therefore, antagonists that inhibit NMDAR-mediated currents specifically by targeting the GluN2B component of the ion channel have the potential to serve as a basis for developing potential therapeutics. The roles of peptidic conantokins, which are potent brain neuronal NMDAR inhibitors, were studied. By using patch-clamp whole-cell analyses in dissociated RGCs and retinal whole-mount RGCs, we evaluated the effects of synthetic conantokin-G (conG) and conantokin-T (conT), which are small γ-carboxyglutamate-containing peptides, on NMDA-mediated excitatory responses in mouse RGCs. Both conG and conT inhibited the NMDA-mediated currents of dark-adapted dissociated and whole-mount RGCs in a dose-dependent, reversible, noncompetitive manner. Inhibition of NMDA-mediated steady-state currents by NMDAR nonsubunit-selective conT was approximately threefold greater than GluN2B-selective conG or ifenprodil, demonstrating its potential ability to inhibit both GluN2A- and GluN2B-containing ion channels in RGCs. Because the extent of inhibition of NMDA-evoked currents by conG and the pharmacologic GluN2B-selective inhibitor ifenprodil were similar (40-45%) to that of the GluN2A-selective antagonist NVP-AAM0077, we conclude that the levels of GluN2A and GluN2B subunits are similar in RGCs. These results provide a novel basis for developing effective neuroprotective agents to aid in the prevention of undesired glutamatergic excitotoxicity in neurodegenerative diseases of the retina and demonstrate functional assembly of NMDARs in RGCs.
Collapse
Affiliation(s)
- Luoxiu Huang
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana
| | | | | |
Collapse
|
11
|
Kunda S, Cheriyan J, Hur M, Balsara RD, Castellino FJ. Antagonist properties of Conus parius peptides on N-methyl-D-aspartate receptors and their effects on CREB signaling. PLoS One 2013; 8:e81405. [PMID: 24260577 PMCID: PMC3832412 DOI: 10.1371/journal.pone.0081405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/22/2013] [Indexed: 02/05/2023] Open
Abstract
Three members of a family of small neurotoxic peptides from the venom of Conus parius, conantokins (Con) Pr1, Pr2, and Pr3, function as antagonists of N-methyl-D-aspartate receptors (NMDAR). We report structural characterizations of these synthetic peptides, and also demonstrate their antagonistic properties toward ion flow through NMDAR ion channels in primary neurons. ConPr1 and ConPr2 displayed moderate increases in α-helicity after addition of Mg2+. Native apo-ConPr3 possessed an α-helical conformation, and the helicity increased only slightly on addition of Mg2+. Additionally, these peptides diminished NMDA/Gly-mediated currents and intracellular Ca2+ (iCa2+) influx in mature rat primary hippocampal neurons. Electrophysiological data showed that these peptides displayed slower antagonistic properties toward the NMDAR than conantokins from other species of cone snails, e.g., ConT and ConG. Furthermore, to demonstrate selectivity of the C. parius-derived conantokins towards specific NMDAR subunits, cortical neurons from GluN2A-/- and GluN2B-/- mice were utilized. Robust inhibition of NMDAR-mediated stimulation in GluN2A-/--derived mouse neurons, as compared to those isolated from GluN2B-/--mouse brains, was observed, suggesting a greater selectivity of these antagonists towards the GluN2B subunit. These C. parius conantokins mildly inhibited NMDAR-induced phosphorylation of CREB at Ser133, suggesting that the peptides modulated iCa2+ entry and, thereby, activation of CREB, a transcription factor that is required for maintaining long-term synaptic activity. Our data mechanistically show that while these peptides effectively antagonize NMDAR-directed current and iCa2+ influx, receptor-coupled CREB signaling is maintained. The consequence of sustained CREB signaling is improved neuronal plasticity and survival during neuropathologies.
Collapse
Affiliation(s)
- Shailaja Kunda
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - John Cheriyan
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Michael Hur
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Rashna D. Balsara
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Francis J. Castellino
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
| |
Collapse
|
12
|
Agrahari G, Liang Z, Mayfield JA, Balsara RD, Ploplis VA, Castellino FJ. Complement-mediated opsonization of invasive group A Streptococcus pyogenes strain AP53 is regulated by the bacterial two-component cluster of virulence responder/sensor (CovRS) system. J Biol Chem 2013; 288:27494-27504. [PMID: 23928307 DOI: 10.1074/jbc.m113.494864] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Group A Streptococcus pyogenes (GAS) strain AP53 is a primary isolate from a patient with necrotizing fasciitis. These AP53 cells contain an inactivating mutation in the sensor component of the cluster of virulence (cov) responder (R)/sensor (S) two-component gene regulatory system (covRS), which enhances the virulence of the primary strain, AP53/covR(+)S(-). However, specific mechanisms by which the covRS system regulates the survival of GAS in humans are incomplete. Here, we show a key role for covRS in the regulation of opsonophagocytosis of AP53 by human neutrophils. AP53/covR(+)S(-) cells displayed potent binding of host complement inhibitors of C3 convertase, viz. Factor H (FH) and C4-binding protein (C4BP), which concomitantly led to minimal C3b deposition on AP53 cells, further showing that these plasma protein inhibitors are active on GAS cells. This resulted in weak killing of the bacteria by human neutrophils and a corresponding high death rate of mice after injection of these cells. After targeted allelic alteration of covS(-) to wild-type covS (covS(+)), a dramatic loss of FH and C4BP binding to the AP53/covR(+)S(+) cells was observed. This resulted in elevated C3b deposition on AP53/covR(+)S(+) cells, a high level of opsonophagocytosis by human neutrophils, and a very low death rate of mice infected with AP53/covR(+)S(+). We show that covRS is a critical transcriptional regulator of genes directing AP53 killing by neutrophils and regulates the levels of the receptors for FH and C4BP, which we identify as the products of the fba and enn genes, respectively.
Collapse
Affiliation(s)
- Garima Agrahari
- W. M. Keck Center for Transgene Research; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | | | | | - Rashna D Balsara
- W. M. Keck Center for Transgene Research; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Victoria A Ploplis
- W. M. Keck Center for Transgene Research; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Francis J Castellino
- W. M. Keck Center for Transgene Research; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556.
| |
Collapse
|
13
|
Liang Z, Zhang Y, Agrahari G, Chandrahas V, Glinton K, Donahue DL, Balsara RD, Ploplis VA, Castellino FJ. A natural inactivating mutation in the CovS component of the CovRS regulatory operon in a pattern D Streptococcal pyogenes strain influences virulence-associated genes. J Biol Chem 2013; 288:6561-73. [PMID: 23316057 DOI: 10.1074/jbc.m112.442657] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A skin-tropic invasive group A Streptococcus pyogenes (GAS) strain, AP53, contains a natural inactivating mutation in the covS gene (covS(M)) of the two-component responder (CovR)/sensor (CovS) gene regulatory system. The effects of this mutation on specific GAS virulence determinants have been assessed, with emphasis on expression of the extracellular protease, streptococcal pyrogenic exotoxin B (SpeB), capsular hyaluronic acid, and proteins that allow host plasmin assembly on the bacterial surface, viz. a high affinity plasminogen (Pg)/plasmin receptor, Pg-binding group A streptococcal M protein (PAM), and the human Pg activator streptokinase. To further illuminate mechanisms of the functioning of CovRS in the virulence of AP53, two AP53 isogenic strains were generated, one in which the natural covS(M) gene was mutated to WT-covS (AP53/covS(WT)) and a strain that contained an inactivated covR gene (AP53/ΔcovR). Two additional strains that do not contain PAM, viz. WT-NS931 and NS931/covS(M), were also employed. SpeB was not measurably expressed in strains containing covR(WT)/covS(M), whereas in strains with natural or engineered covR(WT)/covS(WT), SpeB expression was highly up-regulated. Alternatively, capsule synthesis via the hasABC operon was enhanced in strain AP53/covS(M), whereas streptokinase expression was only slightly affected by the covS inactivation. PAM expression was not substantially influenced by the covS mutation, suggesting that covRS had minimal effects on the mga regulon that controls PAM expression. These results demonstrate that a covS inactivation results in virulence gene alterations and also suggest that the CovR phosphorylation needed for gene up- or down-regulation can occur by alternative pathways to CovS kinase.
Collapse
Affiliation(s)
- Zhong Liang
- WM Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Castellino FJ, Liang Z, Davis PK, Balsara RD, Musunuru H, Donahue DL, Smith DL, Sandoval-Cooper MJ, Ploplis VA, Walsh M. Abnormal whole blood thrombi in humans with inherited platelet receptor defects. PLoS One 2012; 7:e52878. [PMID: 23300803 PMCID: PMC3532496 DOI: 10.1371/journal.pone.0052878] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/22/2012] [Indexed: 11/18/2022] Open
Abstract
To delineate the critical features of platelets required for formation and stability of thrombi, thromboelastography and platelet aggregation measurements were employed on whole blood of normal patients and of those with Bernard-Soulier Syndrome (BSS) and Glanzmann's Thrombasthenia (GT). We found that separation of platelet activation, as assessed by platelet aggregation, from that needed to form viscoelastic stable whole blood thrombi, occurred. In normal human blood, ristocetin and collagen aggregated platelets, but did not induce strong viscoelastic thrombi. However, ADP, arachidonic acid, thrombin, and protease-activated-receptor-1 and -4 agonists, stimulated both processes. During this study, we identified the genetic basis of a very rare double heterozygous GP1b deficiency in a BSS patient, along with a new homozygous GP1b inactivating mutation in another BSS patient. In BSS whole blood, ADP responsiveness, as measured by thrombus strength, was diminished, while ADP-induced platelet aggregation was normal. Further, the platelets of 3 additional GT patients showed very weak whole blood platelet aggregation toward the above agonists and provided whole blood thrombi of very low viscoelastic strength. These results indicate that measurements of platelet counts and platelet aggregability do not necessarily correlate with generation of stable thrombi, a potentially significant feature in patient clinical outcomes.
Collapse
Affiliation(s)
- Francis J Castellino
- W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana, United States of America.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Balsara RD, Merryman R, Virjee F, Northway C, Castellino FJ, Ploplis VA. A deficiency of uPAR alters endothelial angiogenic function and cell morphology. Vasc Cell 2011; 3:10. [PMID: 21535874 PMCID: PMC3105951 DOI: 10.1186/2045-824x-3-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [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: 02/21/2011] [Accepted: 05/02/2011] [Indexed: 01/19/2023] Open
Abstract
The angiogenic potential of a cell requires dynamic reorganization of the cytoskeletal architecture that involves the interaction of urokinase-type plasminogen activator receptor (uPAR) with the extracellular matrix. This study focuses on the effect of uPAR deficiency (uPAR-/-) on angiogenic function and associated cytoskeletal organization. Utilizing murine endothelial cells, it was observed that adhesion, migration, proliferation, and capillary tube formation were altered in uPAR-/- cells compared to wild-type (WT) cells. On a vitronectin (Vn) matrix, uPAR-/- cells acquired a "fried egg" morphology characterized by circular actin organization and lack of lamellipodia formation. The up-regulation of β1 integrin, FAK(P-Tyr925), and paxillin (P-Tyr118), and decreased Rac1 activation, suggested increased focal adhesions, but delayed focal adhesion turnover in uPAR-/- cells. This accounted for the enhanced adhesion, but attenuated migration, on Vn. VEGF-enriched Matrigel implants from uPAR-/- mice demonstrated a lack of mature vessel formation compared to WT mice. Collectively, these results indicate that a uPAR deficiency leads to decreased angiogenic functions of endothelial cells.
Collapse
Affiliation(s)
- Rashna D Balsara
- W, M, Keck Center for Transgene Research, University of Notre Dame, 230 Raclin-Carmichael Hall, Notre Dame, Indiana 46556, USA.
| | | | | | | | | | | |
Collapse
|
16
|
Huang L, Balsara RD, Sheng Z, Castellino FJ. Conantokins inhibit NMDAR-dependent calcium influx in developing rat hippocampal neurons in primary culture with resulting effects on CREB phosphorylation. Mol Cell Neurosci 2010; 45:163-72. [PMID: 20600930 DOI: 10.1016/j.mcn.2010.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/10/2010] [Accepted: 06/11/2010] [Indexed: 11/29/2022] Open
Abstract
The effects of conantokin (con)-G, con-R[1-17], and con-T on ion flow through N-methyl-D-aspartate receptor (NMDAR) ion channels were determined in cultured primary rat hippocampal neurons. The potency of con-G diminished, whereas inhibition by con-R[1-17] and con-T did not change, as the neurons matured. Con-G, con-R[1-17], and con-T effectively diminished NMDA-induced Ca(2+) influx into the cells. A similar age-dependent decrease in con-G-mediated inhibition of the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) was observed, compared to con-R[1-17] and con-T. The effects of the conantokins on NMDA-induced cAMP response element-binding protein (CREB) phosphorylation in immature (DIV 9) and mature (DIV 16) neurons showed that, at DIV 9, con-G, con-R[1-17], and con-T inhibited NMDA-mediated P-CREB levels, whereas in DIV 16 neurons the conantokins did not inhibit overall levels of NMDA-induced P-CREB. In contrast, P-CREB levels were enhanced through inhibition of the protein phosphatases, PP1 and PP2B (calcineurin). This ability of conantokins to sustain CREB phosphorylation can thus enhance neuronal survival and plasticity.
Collapse
Affiliation(s)
- Luoxiu Huang
- WM Keck Center for Transgene Research, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | | | | |
Collapse
|
17
|
Balsara RD, Ploplis VA. Plasminogen activator inhibitor-1: the double-edged sword in apoptosis. Thromb Haemost 2008; 100:1029-1036. [PMID: 19132226 PMCID: PMC3674867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Plasminogen activator inhibitor type-1 (PAI-1) is a multi-functional protein. It is a fast-acting inhibitor of plasminogen activators; urokinase-plasminogen activator and tissue type plasminogen activator, and also plays an important role in regulating cell proliferation, adhesion, migration, and signal transduction pathways. These biological events are important processes during angiogenesis and restenosis. PAI-1 has been shown to regulate proliferation, migration, and apoptosis of vascular smooth muscle cells and endothelial cells. The ability of PAI-1 to regulate cellular proliferation and migration has been attributed to its ability to control plasmin production, modify signaling pathways, and its inherent multifactorial ability to bind to vitronectin and lipoprotein receptor-related protein. However, the mechanism by which PAI-1 regulates the apoptotic pathway is not well understood. Evidence from the literature suggests that PAI-1 or its deficiency alters key signalling pathways, such as the PI3-k/Akt and the Jak/STAT pathways, and is involved in maintaining endothelial cell integrity thereby regulating cell death. Other investigators have demonstrated that PAI-1 directly binds to caspases as a mechanism of PAI-1-mediated cellular apoptosis. Moreover, results from studies assessing the role of PAI-1 in apoptosis have suggested that PAI-1 can exert pathogenic or protective effects, which may be related to the disease model or type of injury employed.
Collapse
|
18
|
Balsara RD. Wnt signaling. Curr Drug Targets 2008; 9:511-2. [PMID: 18673237 DOI: 10.2174/138945008784911804] [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: 11/22/2022]
|
19
|
Abstract
It is well documented that elevated levels of PAI-1 in plasma can decrease the fibrinolytic activity in blood with an associated increased risk of thrombus formation. A diverse range of molecules including bacterial lipopolysaccharide (LPS), the inflammatory mediators tumor necrosis factor alpha (TNFalpha) and interleukins, thrombin, transforming growth factor-beta (TGF-beta), and hormones regulate the synthesis of plasma PAI-1. Therefore, it is of clinical importance to restore the fibrinolytic balance. For a drug to be effective in controlling the synthesis of PAI-1, sufficient insight into the signal transduction pathways that control its regulation is desirable, which could serve as logical targets for the development of pharmaceuticals. Some key signaling pathways have been identified with the aid of pharmacological inhibitors, involved in the up-regulation of PAI-1 in context with several diseases, including obesity, insulin resistance, diabetic nephropathy, glomulonephritis, and pulmonary fibrosis. Furthermore, independent of its inhibitory activity PAI-1 mediates interactions with vitronectin (VN) and low density lipoprotein receptor-related protein (LRP) which modifies basic cell behaviors of proliferation, migration, and attachment. Intriguingly, it has been shown that both anti-fibrinolytic and non-fibrinolytic-related functions of PAI-1 may have overlapping roles in many diseases that are poorly understood. Tailoring knock-in mice with site-specific alterations that diminish the inhibitory activity, VN-binding, and LRP-binding activity of PAI-1 are useful tools for manipulation of biochemical properties, in vivo, and evaluating therapeutics.
Collapse
Affiliation(s)
- R D Balsara
- W. M. Keck Center for Transgene Research, University of Notre Dame, Indiana 46556, USA
| | | | | |
Collapse
|
20
|
Balsara RD, Castellino FJ, Ploplis VA. A Novel Function of Plasminogen Activator Inhibitor-1 in Modulation of the AKT Pathway in Wild-type and Plasminogen Activator Inhibitor-1-deficient Endothelial Cells. J Biol Chem 2006; 281:22527-36. [PMID: 16785241 DOI: 10.1074/jbc.m512819200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell proliferation, an event associated with angiogenesis, involves coordinated activities of a number of proteins. The role of plasminogen activator inhibitor-1 (PAI-1) in angiogenesis remains controversial. Utilizing proliferating PAI-1-/- endothelial cells (EC), the impact of a host PAI-1 deficiency on Akt activation was evaluated. Hyperactivation of Akt(Ser(P)473) was observed in PAI-1-/- EC, and this was probably due to enhanced inactivation of tumor suppressor PTEN, thus rendering the cells resistant to apoptotic signals. Higher levels of inactivated caspase-9 in PAI-1-/- EC led to lower levels of procaspase-3 and cleaved caspase-3, thereby promoting survival. These effects were reversed when recombinant PAI-1 was added to PAI-1-/- EC. Additional studies demonstrated that regulation of proliferation is dependent on its interaction with low density lipoprotein receptor-related protein. Thus, PAI-1 is a negative regulator of cell growth, exerting its effect on the phosphatidylinositol 3-kinase/Akt pathway and allowing controlled cell proliferation.
Collapse
Affiliation(s)
- Rashna D Balsara
- W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | | |
Collapse
|
21
|
Xu Z, Balsara RD, Gorlatova NV, Lawrence DA, Castellino FJ, Ploplis VA. Conservation of critical functional domains in murine plasminogen activator inhibitor-1. J Biol Chem 2004; 279:17914-20. [PMID: 14963029 DOI: 10.1074/jbc.m314197200] [Citation(s) in RCA: 25] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasminogen activator inhibitor-1 is the main physiological regulator of tissue-type plasminogen activator in normal plasma. In addition to its critical function in fibrinolysis, plasminogen activator inhibitor-1 has been implicated in roles in other physiological and pathophysiological processes. To investigate structure-function aspects of mouse plasminogen activator inhibitor-1, the recombinant protein was expressed in Escherichia coli and purified. Five variant recombinant murine proteins (R76E, Q123K, R346A, R101A, and Q123K/R101A) were also generated using site-directed mutagenesis. The variant (R346A) was found to be defective in its inhibitory activity against tissue plasminogen activator relative to its wild-type counterpart. Enzyme-linked immunosorbent assay and surface plasmon resonance experiments demonstrated reduced vitronectin-binding affinity of the (Q123K) variant (K(D) = 1800 nm) relative to the wild-type protein (K(D) = 5.4 nm). Kinetic analyses indicated that the (Q123K) variant had a slower association (k(on) = 2.92 x 10(4) m(-1) s(-1)) to, and a faster dissociation from, vitronectin (k(off) = 5.3 x 10(-2) s(-1)), (wild-type k(on) = 1.03 x 10(6) m(-1) s(-1) and k(off) = 5.27 x 10(-3) s(-1)). The Q123K/R101A variant demonstrated an even lower vitronectin-binding ability. Low density lipoprotein receptor-related protein binding was decreased for the (R76E) variant. It was also demonstrated that the plasminogen activator inhibitor-1/vitronectin complex decreased the interaction of plasminogen activator inhibitor-1 with low density lipoprotein receptor-related protein. These results indicate that the complex interactions traditionally associated with different plasminogen activator inhibitor-1 functions apply to the murine system, thus showing a commonality of subtle functions among different species and evolutionary conservation of this protein. Further, this study provides additional evidence that the human hemostasis system can be studied effectively in the mouse, which is a great asset for investigations with gene-altered mice.
Collapse
Affiliation(s)
- Zhi Xu
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | | | | | | | | | | |
Collapse
|
22
|
Rajendran RR, Nye AC, Frasor J, Balsara RD, Martini PGV, Katzenellenbogen BS. Regulation of nuclear receptor transcriptional activity by a novel DEAD box RNA helicase (DP97). J Biol Chem 2003; 278:4628-38. [PMID: 12466272 DOI: 10.1074/jbc.m210066200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a novel DEAD box RNA helicase (97 kDa, DP97) from a breast cancer cDNA library that interacts in a hormone-dependent manner with nuclear receptors and represses their transcriptional activity. DP97 has RNA-dependent ATPase activity, and mapping studies localize the interacting regions of DP97 and nuclear receptors to the C-terminal region of DP97 and the hormone binding/activation function-2 region of estrogen receptors (ER), as well as several other nuclear receptors. Repression by DP97 maps to a small region (amino acids 589-631) that has homology to a repression domain in the corepressor protein NCoR2/SMRTe. This region of DP97 is necessary and sufficient for its intrinsic repression activity. The N-terminal helicase region of DP97 is, however, dispensable for its transcriptional repressor activity. The knockdown of endogenous cellular DP97 by antisense DP97 or RNA interference (siRNA for DP97) results in significant enhancement of the expression of estradiol-ER-stimulated genes and attenuation of the repression of genes inhibited by the estradiol-ER. This implies that endogenous DP97 normally dampens stimulation and intensifies repression of estradiol-ER-regulated genes. Our findings add to the growing evidence that RNA helicases can associate with nuclear receptors and function as coregulators to modulate receptor transcriptional activity.
Collapse
Affiliation(s)
- Ramji R Rajendran
- Department of Cell and Structural Biology, University of Illinois, Urbana, Illinois 61801, USA
| | | | | | | | | | | |
Collapse
|
23
|
Balsara RD, Joshi VP. Molecular basis of UV-sensitive mutant strain MBH3 of Haemophilus influenzae Rd: identification of mutation in the uvrA gene. J Environ Pathol Toxicol Oncol 2001; 20:27-32. [PMID: 11215703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
We have previously reported on cloning a DNA repair gene designated as uvr3 by virtue of its ability to phenotypically complement the UV sensitivity of mutant strain MBH3. Subsequently, we identified the uvr3 gene to be the uvrA gene (gene identification number HI0249) of Haemophilus influenzae Rd. The uvrA gene is a component of the UvrABC excision repair pathway. We studied molecular basis of the UV sensitivity of the MBH3 strain and identified a G-->A transition at nucleotide position 2700 of the uvrA gene, altering the Trp-900 codon (TGG) to a nonsense codon (TGA). Thus, the UvrA protein produced in the mutant strain MBH3 is likely to be truncated and unable to carry out the UV-induced DNA repair, thereby rendering the strain UV sensitive.
Collapse
Affiliation(s)
- R D Balsara
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801, USA
| | | |
Collapse
|
24
|
Balsara RD, Joshi VP. Molecular Basis of UV-Sensitive Mutant Strain MBH3 of Haemophilus Influenzae Rd: Identification of Mutation in the uvrA Gene. J Environ Pathol Toxicol Oncol 2001. [DOI: 10.1615/jenvironpatholtoxicoloncol.v20.i1.50] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|