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Jimenez EC. Peptide antagonists of NMDA receptors: Structure-activity relationships for potential therapeutics. Peptides 2022; 153:170796. [PMID: 35367253 DOI: 10.1016/j.peptides.2022.170796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 03/26/2022] [Accepted: 03/27/2022] [Indexed: 12/19/2022]
Abstract
The N-methyl-D-aspartate (NMDA) receptors are heteromeric cation channels involved in memory, learning, and synaptic plasticity. The dysfunction associated with NMDA receptors results in neurodegenerative conditions. The conantokins comprise a family of Conus venom peptides that induce sleep upon intracranial injection into young mice and are known to be NMDA receptor antagonists. This work comprehensibly documents the conantokins that have been characterized to date, focusing on the biochemistry, solution structures in the presence or absence of divalent cations, functions as selective NMDA receptor antagonists, and structure-activity relationships. Furthermore, the applications of conantokins as potential therapeutics for certain neurological conditions, including neuropathic pain, epilepsy, and ischaemia that are linked to NMDA receptor dysfunction are reviewed.
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Affiliation(s)
- Elsie C Jimenez
- Department of Physical Sciences, College of Science, University of the Philippines Baguio, Baguio City 2600, Philippines.
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Liu LL, Spix NJ, Zhang DQ. NMDA Receptors Contribute to Retrograde Synaptic Transmission from Ganglion Cell Photoreceptors to Dopaminergic Amacrine Cells. Front Cell Neurosci 2017; 11:279. [PMID: 28959188 PMCID: PMC5603656 DOI: 10.3389/fncel.2017.00279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/29/2017] [Indexed: 11/13/2022] Open
Abstract
Recently, a line of evidence has demonstrated that the vertebrate retina possesses a novel retrograde signaling pathway. In this pathway, phototransduction is initiated by the photopigment melanopsin, which is expressed in a small population of retinal ganglion cells. These ganglion cell photoreceptors then signal to dopaminergic amacrine cells (DACs) through glutamatergic synapses, influencing visual light adaptation. We have previously demonstrated that in Mg2+-containing solution, α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptors mediate this glutamatergic transmission. Here, we demonstrate that removing extracellular Mg2+ enhances melanopsin-based DAC light responses at membrane potentials more negative than −40 mV. Melanopsin-based responses in Mg2+-free solution were profoundly suppressed by the selective N-methyl-D-aspartate (NMDA) receptor antagonist D-AP5. In addition, application of NMDA to the retina produced excitatory inward currents in DACs. These data strongly suggest that DACs express functional NMDA receptors. We further found that in the presence of Mg2+, D-AP5 reduced the peak amplitude of melanopsin-based DAC responses by ~70% when the cells were held at their resting membrane potential (−50 mV), indicating that NMDA receptors are likely to contribute to retrograde signal transmission to DACs under physiological conditions. Moreover, our data show that melanopsin-based NMDA-receptor-mediated responses in DACs are suppressed by antagonists specific to either the NR2A or NR2B receptor subtype. Immunohistochemical results show that NR2A and NR2B subunits are expressed on DAC somata and processes. These results suggest that DACs express functional NMDA receptors containing both NR2A and NR2B subunits. Collectively, our data reveal that, along with AMPA receptors, NR2A- and NR2B-containing NMDA receptors mediate retrograde signal transmission from ganglion cell photoreceptors to DACs.
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Affiliation(s)
- Lei-Lei Liu
- Eye Research Institute, Oakland UniversityRochester, MI, United States
| | - Nathan J Spix
- Eye Research Institute, Oakland UniversityRochester, MI, United States
| | - Dao-Qi Zhang
- Eye Research Institute, Oakland UniversityRochester, MI, United States
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Zhang J, Liu R, Kuang HY, Gao XY, Liu HL. Protective treatments and their target retinal ganglion cells in diabetic retinopathy. Brain Res Bull 2017; 132:53-60. [DOI: 10.1016/j.brainresbull.2017.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 05/10/2017] [Indexed: 12/19/2022]
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Abstract
Peptide-based drug discovery has experienced a remarkable resurgence within the past decade due to the emerging class of inhibitors known as stapled peptides. Stapled peptides are therapeutic protein mimetics that have been locked within a specific conformational structure by hydrocarbon stapling. These peptides are highly important in selectively impairing disease-relevant protein–protein interactions and exhibit significant pharmacokinetic advantages over other forms of therapeutics in terms of affinity, specificity, size, synthetic accessibility and resistance to proteolytic degradation. A series of stapled peptides are currently in development, and the potential successes of these peptides, either as single-agent treatments or as combinational treatments with other therapeutic modalities, could potentially change the landscape of protein therapeutic development. Here, we provide examples of successful discovery efforts to illustrate the research strategies of stapled peptides in drug design and development.
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Higashi DL, Biais N, Donahue DL, Mayfield JA, Tessier CR, Rodriguez K, Ashfeld BL, Luchetti J, Ploplis VA, Castellino FJ, Lee SW. Activation of band 3 mediates group A Streptococcus streptolysin S-based beta-haemolysis. Nat Microbiol 2016; 1:15004. [PMID: 27571972 DOI: 10.1038/nmicrobiol.2015.4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/18/2015] [Indexed: 11/09/2022]
Abstract
Streptococcus pyogenes, or group A Streptococcus (GAS), is a human bacterial pathogen that can manifest as a range of diseases from pharyngitis and impetigo to severe outcomes such as necrotizing fasciitis and toxic shock syndrome. GAS disease remains a global health burden with cases estimated at over 700 million annually and over half a million deaths due to severe infections(1). For over 100 years, a clinical hallmark of diagnosis has been the appearance of complete (beta) haemolysis when grown in the presence of blood. This activity is due to the production of a small peptide toxin by GAS known as streptolysin S. Although it has been widely held that streptolysin S exerts its lytic activity through membrane disruption, its exact mode of action has remained unknown. Here, we show, using high-resolution live cell imaging, that streptolysin S induces a dramatic osmotic change in red blood cells, leading to cell lysis. This osmotic change was characterized by the rapid influx of Cl(-) ions into the red blood cells through SLS-mediated disruption of the major erythrocyte anion exchange protein, band 3. Chemical inhibition of band 3 function significantly reduced the haemolytic activity of streptolysin S, and dramatically reduced the pathology in an in vivo skin model of GAS infection. These results provide key insights into the mechanism of streptolysin S-mediated haemolysis and have implications for the development of treatments against GAS.
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Affiliation(s)
- Dustin L Higashi
- Department of Biological Sciences, University of Notre Dame, 100 Galvin Life Sciences Center, Notre Dame, Indiana 46556, USA
| | - Nicolas Biais
- Biology Department, Brooklyn College CUNY, New York 11210, USA
| | - Deborah L Donahue
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Jeffrey A Mayfield
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Charles R Tessier
- Indiana University School of Medicine, South Bend, Indiana 46617, USA
| | - Kevin Rodriguez
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Brandon L Ashfeld
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Jeffrey Luchetti
- Department of Biological Sciences, University of Notre Dame, 100 Galvin Life Sciences Center, Notre Dame, Indiana 46556, USA
| | - Victoria A Ploplis
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Francis J Castellino
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Shaun W Lee
- Department of Biological Sciences, University of Notre Dame, 100 Galvin Life Sciences Center, Notre Dame, Indiana 46556, USA.,W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Retinal Cell Degeneration in Animal Models. Int J Mol Sci 2016; 17:ijms17010110. [PMID: 26784179 PMCID: PMC4730351 DOI: 10.3390/ijms17010110] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 12/25/2015] [Accepted: 01/08/2016] [Indexed: 01/01/2023] Open
Abstract
The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced), autoimmune (experimental autoimmune encephalomyelitis), mechanical stress (optic nerve crush-induced, light-induced) and ischemia (transient retinal ischemia-induced). The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insight into the underlying mechanisms of the disease, and will facilitate the development of novel effective therapeutic drugs to treat retinal cell damage.
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Zhang C, Wang Z, Zhao J, Li Q, Huang C, Zhu L, Lu D. Neuroprotective Effect of Lutein on NMDA-Induced Retinal Ganglion Cell Injury in Rat Retina. Cell Mol Neurobiol 2015; 36:531-40. [DOI: 10.1007/s10571-015-0231-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 06/20/2015] [Indexed: 12/31/2022]
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