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Xu Z, Lei Y, Qin H, Zhang S, Li P, Yao K. Sigma-1 Receptor in Retina: Neuroprotective Effects and Potential Mechanisms. Int J Mol Sci 2022; 23:ijms23147572. [PMID: 35886921 PMCID: PMC9321618 DOI: 10.3390/ijms23147572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/03/2022] [Accepted: 07/05/2022] [Indexed: 02/04/2023] Open
Abstract
Retinal degenerative diseases are the major factors leading to severe visual impairment and even irreversible blindness worldwide. The therapeutic approach for retinal degenerative diseases is one extremely urgent and hot spot in science research. The sigma-1 receptor is a novel, multifunctional ligand-mediated molecular chaperone residing in endoplasmic reticulum (ER) membranes and the ER-associated mitochondrial membrane (ER-MAM); it is widely distributed in numerous organs and tissues of various species, providing protective effects on a variety of degenerative diseases. Over three decades, considerable research has manifested the neuroprotective function of sigma-1 receptor in the retina and has attempted to explore the molecular mechanism of action. In the present review, we will discuss neuroprotective effects of the sigma-1 receptor in retinal degenerative diseases, mainly in aspects of the following: the localization in different types of retinal neurons, the interactions of sigma-1 receptors with other molecules, the correlated signaling pathways, the influence of sigma-1 receptors to cellular functions, and the potential therapeutic effects on retinal degenerative diseases.
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Cellular localization of the FMRP in rat retina. Biosci Rep 2020; 40:225004. [PMID: 32452512 PMCID: PMC7295639 DOI: 10.1042/bsr20200570] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/17/2020] [Accepted: 05/22/2020] [Indexed: 01/05/2023] Open
Abstract
The fragile X mental retardation protein (FMRP) is a regulator of local translation through its mRNA targets in the neurons. Previous studies have demonstrated that FMRP may function in distinct ways during the development of different visual subcircuits. However, the localization of the FMRP in different types of retinal cells is unclear. In this work, the FMRP expression in rat retina was detected by Western blot and immunofluorescence double labeling. Results showed that the FMRP expression could be detected in rat retina and that the FMRP had a strong immunoreaction (IR) in the ganglion cell (GC) layer, inner nucleus layer (INL), and outer plexiform layer (OPL) of rat retina. In the outer retina, the bipolar cells (BCs) labeled by homeobox protein ChX10 (ChX10) and the horizontal cells (HCs) labeled by calbindin (CB) were FMRP-positive. In the inner retina, GABAergic amacrine cells (ACs) labeled by glutamate decarbonylase colocalized with the FMRP. The dopaminergic ACs (tyrosine hydroxylase marker) and cholinergic ACs (choline acetyltransferase (ChAT) marker) were co-labeled with the FMRP. In most GCs (labeled by Brn3a) and melanopsin-positive intrinsically photosensitive retinal GCs (ipRGCs) were also FMRP-positive. The FMRP expression was observed in the cellular retinal binding protein-positive Müller cells. These results suggest that the FMRP could be involved in the visual pathway transmission.
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Smith SB, Wang J, Cui X, Mysona BA, Zhao J, Bollinger KE. Sigma 1 receptor: A novel therapeutic target in retinal disease. Prog Retin Eye Res 2018; 67:130-149. [PMID: 30075336 PMCID: PMC6557374 DOI: 10.1016/j.preteyeres.2018.07.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 07/27/2018] [Accepted: 07/30/2018] [Indexed: 02/08/2023]
Abstract
Retinal degenerative diseases are major causes of untreatable blindness worldwide and efficacious treatments for these diseases are sorely needed. A novel target for treatment of retinal disease is the transmembrane protein Sigma 1 Receptor (Sig1R). This enigmatic protein is an evolutionary isolate with no known homology to any other protein. Sig1R was originally thought to be an opioid receptor. That notion has been dispelled and more recent pharmacological and molecular studies suggest that it is a pluripotent modulator with a number of biological functions, many of which are relevant to retinal disease. This review provides an overview of the discovery of Sig1R and early pharmacologic studies that led to the cloning of the Sig1R gene and eventual elucidation of its crystal structure. Studies of Sig1R in the eye were not reported until the late 1990s, but since that time there has been increasing interest in the potential role of Sig1R as a target for retinal disease. Studies have focused on elucidating the mechanism(s) of Sig1R function in retina including calcium regulation, modulation of oxidative stress, ion channel regulation and molecular chaperone activity. Mechanistic studies have been performed in isolated retinal cells, such as Müller glial cells, microglial cells, optic nerve head astrocytes and retinal ganglion cells as well as in the intact retina. Several compelling studies have provided evidence of powerful in vivo neuroprotective effects against ganglion cell loss as well as photoreceptor cell loss. Also described are studies that have examined retinal structure/function in various models of retinal disease in which Sig1R is absent and reveal that these phenotypes are accelerated compared to retinas of animals that express Sig1R. The collective evidence from analysis of studies over the past 20 years is that Sig1R plays a key role in modulating retinal cellular stress and that it holds great promise as a target in retinal neurodegenerative disease.
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Affiliation(s)
- Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University 30912, Augusta, GA, USA.
| | - Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Xuezhi Cui
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Barbara A Mysona
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Jing Zhao
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University 30912, Augusta, GA, USA
| | - Kathryn E Bollinger
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University 30912, Augusta, GA, USA
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Mysona B, Kansara N, Zhao J, Bollinger K. The Role of Sigma 1 Receptor as a Neuroprotective Target in Glaucoma. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:299-307. [PMID: 28315279 DOI: 10.1007/978-3-319-50174-1_20] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The role of sigma 1 receptor (S1R) in glaucoma is emerging as a promising field of study. Glaucoma is an optic neuropathy that shares common pathogenic mechanisms with other neurodegenerative diseases such as Alzheimer's and Parkinson's disease . S1R modulates multiple cellular functions associated with neurodegeneration . These include Ca2+ ion homeostasis, endoplasmic reticulum (ER) and oxidative stress , survival signaling pathways, neurotrophin secretion, and glial activation. S1R may also have neurorestorative properties including enhancement of neuronal plasticity and neurite outgrowth. Recent studies using agonists for S1R within the eye provide hope that it could be a therapeutic target for glaucoma. Understanding the role of S1R in glaucoma may help us to stop the progression of this sight threatening disease.
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Affiliation(s)
- Barbara Mysona
- Departments of Cellular Biology and Anatomy and Ophthalmology and the James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Neil Kansara
- Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
- The James and Jean Culver Vision Discovery Institute, Augusta, GA, 30912, USA
| | - Jing Zhao
- The James and Jean Culver Vision Discovery Institute, Augusta, GA, 30912, USA
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Kathryn Bollinger
- Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
- The James and Jean Culver Vision Discovery Institute, Augusta, GA, 30912, USA.
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, 30912, USA.
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Wang J, Cui X, Roon P, Saul A, Smith SB. The Role of Sigma1R in Mammalian Retina. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:267-284. [PMID: 28315277 DOI: 10.1007/978-3-319-50174-1_18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This review article focuses on studies of Sigma 1 Receptor (Sigma1R) and retina . It provides a brief overview of the earliest pharmacological studies performed in the late 1990s that provided evidence of the presence of Sigma1R in various ocular tissues. It then describes work from a number of labs concerning the location of Sigma1R in several retinal cell types including ganglion, Müller glia , and photoreceptors . The role of Sigma1R ligands in retinal neuroprotection is emphasized. Early studies performed in vitro clearly showed that targeting Sigma1R could attenuate stress-induced retinal cell loss. These studies were followed by in vivo experiments. Data about the usefulness of targeting Sigma1R to prevent ganglion cell loss associated with diabetic retinopathy are reviewed. Mechanisms of Sigma1R-mediated retinal neuroprotection involving Müller cells , especially in modulating oxidative stress are described along with information about the retinal phenotype of mice lacking Sigma1R (Sigma1R -/- mice). The retina develops normally in Sigma1R -/- mice, but after many months there is evidence of apoptosis in the optic nerve head, decreased ganglion cell function and eventual loss of these cells. Additional studies using the Sigma1R -/- mice provide strong evidence that in the retina, Sigma1R plays a key role in modulating cellular stress. Recent work has shown that targeting Sigma1R may extend beyond protection of ganglion cells to include photoreceptor cell degeneration as well.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB 1114, Augusta, GA, 30912-2000, USA
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Xuezhi Cui
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB 1114, Augusta, GA, 30912-2000, USA
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Penny Roon
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB 1114, Augusta, GA, 30912-2000, USA
| | - Alan Saul
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB 1114, Augusta, GA, 30912-2000, USA
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Sylvia B Smith
- Departments of Cellular Biology and Anatomy and Ophthalmology and the James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
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Mavlyutov TA, Guo LW. Peeking into Sigma-1 Receptor Functions Through the Retina. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:285-297. [PMID: 28315278 PMCID: PMC6283661 DOI: 10.1007/978-3-319-50174-1_19] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review discusses recent advances towards understanding the sigma-1 receptor (S1R) as an endogenous neuro-protective mechanism in the retina , a favorable experimental model system. The exquisite architecture of the mammalian retina features layered and intricately wired neurons supported by non-neuronal cells. Ganglion neurons, photoreceptors , as well as the retinal pigment epithelium, are susceptible to degeneration that leads to major retinal diseases such as glaucoma , diabetic retinopathy , and age-related macular degeneration (AMD), and ultimately, blindness. The S1R protein is found essentially in every retinal cell type, with high abundance in the ganglion cell layer. Ultrastructural studies of photoreceptors, bipolar cells, and ganglion cells show a predominant localization of S1R in the nuclear envelope. A protective role of S1R for ganglion and photoreceptor cells is supported by in vitro and in vivo experiments. Most recently, studies suggest that S1R may also protect retinal neurons via its activities in Müller glia and microglia. The S1R functions in the retina may be attributed to a reduction of excitotoxicity, oxidative stress , ER stress response, or inflammation. S1R knockout mice are being used to delineate the S1R-specific effects. In summary, while significant progress has been made towards the objective of establishing a S1R-targeted paradigm for retinal neuro-protection , critical questions remain. In particular, context-dependent effects and potential side effects of interventions targeting S1R need to be studied in more diverse and more clinically relevant animal models.
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Affiliation(s)
- Timur A Mavlyutov
- Department of Surgery and McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, 53705, Madison, WI, USA
| | - Lian-Wang Guo
- Department of Surgery and McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, 53705, Madison, WI, USA
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Activation of the sigma receptor 1 modulates AMPA receptor-mediated light-evoked excitatory postsynaptic currents in rat retinal ganglion cells. Neuroscience 2016; 332:53-60. [PMID: 27373906 DOI: 10.1016/j.neuroscience.2016.06.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 06/15/2016] [Accepted: 06/24/2016] [Indexed: 11/20/2022]
Abstract
Sigma receptor (σR), a unique receptor family, is classified into three subtypes: σR1, σR2 and σR3. It was previously shown that σR1 activation induced by 1μM SKF10047 (SKF) suppressed N-methyl-d-aspartate (NMDA) receptor-mediated responses of rat retinal ganglion cells (GCs) and the suppression was mediated by a distinct Ca(2+)-dependent phospholipase C (PLC)-protein kinase C (PKC) pathway. In the present work, using whole-cell patch-clamp techniques in rat retinal slice preparations, we further demonstrate that SKF of higher dosage (50μM) significantly suppressed AMPA receptor (AMPAR)-mediated light-evoked excitatory postsynaptic currents (L-EPSCs) of retinal ON-type GCs (ON GCs), and the effect was reversed by the σR1 antagonist BD1047, suggesting the involvement of σR1. The SKF (50μM) effect was unlikely due to a change in glutamate release from bipolar cells, as suggested by the unaltered paired-pulse ratio (PPR) of AMPAR-mediated EPSCs of ON GCs. SKF (50μM) did not change L-EPSCs of ON GCs when the G protein inhibitor GDP-β-S or the protein kinase G (PKG) inhibitor KT5823 was intracellularly infused. Calcium imaging further revealed that SKF (50μM) did not change intracellular calcium concentration in GCs and persisted to suppress L-EPSCs when intracellular calcium was chelated by BAPTA. The SKF (50μM) effect was intact when protein kinase A (PKA) and phosphatidylinostiol (PI)-PLC signaling pathways were both blocked. We conclude that the SKF (50μM) effect is Ca(2+)-independent, PKG-dependent, but not involving PKA, PI-PLC pathways.
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Wang J, Cui X, Roon P, Smith SB. Role of Sigma 1 Receptor in Retinal Degeneration of the Ins2Akita/+ Murine Model of Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2016; 57:2770-81. [PMID: 27206247 PMCID: PMC4884059 DOI: 10.1167/iovs.15-18995] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/17/2016] [Indexed: 01/31/2023] Open
Abstract
PURPOSE Sigma receptor 1 (Sigma1R), a nonopioid putative molecular chaperone, has neuroprotective properties in retina. This study sought to determine whether delaying administration of (+)-pentazocine, a high-affinity Sigma1R ligand after onset of diabetes in Ins2Akita/+ diabetic mice would afford retinal neuroprotection and to determine consequences on retinal phenotype in Ins2Akita/+ diabetic mice in the absence of Sigma1R. METHODS Ins2Akita/+ diabetic and WT mice received intraperitoneal injections of (+)-pentazocine beginning 4 or 8 weeks after onset of diabetes; eyes were harvested at 25 weeks. Retinal histologic sections were analyzed to determine thicknesses of retinal layers, number of ganglion cells, and evidence of gliosis (increased glial fibrillary acidic protein levels). Ins2Akita/+/Sig1R-/-mice were generated and subjected to in vivo assessment of retinal architecture (optical coherence tomography [OCT]) and retinal vasculature using fluorescein angiography (FA) at 12 and 16 weeks compared with age-matched Ins2Akita/+ mice. Eyes were then harvested for retinal morphometric assessment and gliosis assessment. RESULTS Wild-type mice had 13 ± 0.06 cells/100 μm retinal length; cell bodies in Ins2Akita/+ mice injected 4 and 8 weeks after onset of diabetes with (+)-pentazocine retained significantly more ganglion cells compared with Ins2Akita/+ mice (9 ± 0.04) and demonstrated significant attenuation of gliosis. Ins2Akita/+/Sig1R-/-mouse retinas, analyzed to determine whether the Ins2Akita/+ phenotype was accelerated when lacking Sigma1R, revealed increased nerve fiber layer thickness (OCT), evidence of vitreal opacities, and vessel beading (FA) compared with Ins2Akita/+ mice. Morphometric analysis revealed significantly fewer ganglion cells in Ins2Akita/+/Sig1R-/-mice compared with Ins2Akita/+ mice. CONCLUSIONS Sigma1R may be a novel retinal stress modulator, and targeting it even after disease onset may afford retinal neuroprotection.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Xuezhi Cui
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Penny Roon
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, United States
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States
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Shanmugam AK, Mysona BA, Wang J, Zhao J, Tawfik A, Sanders A, Markand S, Zorrilla E, Ganapathy V, Bollinger KE, Smith SB. Progesterone Receptor Membrane Component 1 (PGRMC1) Expression in Murine Retina. Curr Eye Res 2015; 41:1105-1112. [PMID: 26642738 DOI: 10.3109/02713683.2015.1085579] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Sigma receptors 1 (σR1) and 2 (σR2) are thought to be two distinct proteins which share the ability to bind multiple ligands, several of which are common to both receptors. Whether σR1 and σR2 share overlapping biological functions is unknown. Recently, progesterone receptor membrane component 1 (PGRMC1) was shown to contain the putative σR2 binding site. PGRMC1 has not been studied in retina. We hypothesize that biological interactions between σR1 and PGRMC1 will be evidenced by compensatory upregulation of PGRMC1 in σR1-/- mice. METHODS Immunofluorescence, RT-PCR, and immunoblotting methods were used to analyze expression of PGRMC1 in wild-type mouse retina. Tissues from σR1-/- mice were used to investigate whether a biological interaction exists between σR1 and PGRMC1. RESULTS In the eye, PGRMC1 is expressed in corneal epithelium, lens, ciliary body epithelium, and retina. In retina, PGRMC1 is present in Müller cells and retinal pigment epithelium. This expression pattern is similar, but not identical to σR1. PGRMC1 protein levels in neural retina and eye cup from σR1-/- mice did not differ from wild-type mice. Nonocular tissues, lung, heart, and kidney showed similar Pgrmc1 gene expression in wild-type and σR1-/- mice. In contrast, liver, brain, and intestine showed increased Pgrmc1 gene expression in σR1-/- mice. CONCLUSION Despite potential biological overlap, deletion of σR1 did not result in a compensatory change in PGRMC1 protein levels in σR1-/- mouse retina. Increased Pgrmc1 gene expression in organs with high lipid content such as liver, brain, and intestine indicates a possible tissue-specific interaction between σR1 and PGRMC1. The current studies establish the presence of PGRMC1 in retina and lay the foundation for analysis of its biological function.
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Affiliation(s)
- Arul K Shanmugam
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA
| | - Barbara A Mysona
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA
| | - Jing Wang
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA
| | - Jing Zhao
- b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA.,c Department of Ophthalmology , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA
| | - Amany Tawfik
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA
| | - A Sanders
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA
| | - Shanu Markand
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA
| | - Eric Zorrilla
- d Harold L. Dorris Neurological Research Institute , The Scripps Research Institute , La Jolla , CA , USA
| | - Vadivel Ganapathy
- b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA.,e Department of Cell Biology and Biochemistry , Texas Tech University Health Sciences Center , Lubbock , TX , USA
| | - Kathryn E Bollinger
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA.,c Department of Ophthalmology , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA
| | - Sylvia B Smith
- a Department of Cellular Biology and Anatomy , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA.,b James & Jean Culver Vision Discovery Institute , Georgia Regents University , Augusta , GA , USA.,c Department of Ophthalmology , Medical College of Georgia, Georgia Regents University , Augusta , GA , USA
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Vogler S, Winters H, Pannicke T, Wiedemann P, Reichenbach A, Bringmann A. Sigma-1 receptor activation inhibits osmotic swelling of rat retinal glial (Müller) cells by transactivation of glutamatergic and purinergic receptors. Neurosci Lett 2015; 610:13-8. [PMID: 26499958 DOI: 10.1016/j.neulet.2015.10.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/05/2015] [Accepted: 10/14/2015] [Indexed: 12/28/2022]
Abstract
Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Sigma (σ) receptor activation is known to have neuroprotective effects in the retina. Here, we show that the nonselective σ receptor agonist ditolylguanidine, and the selective σ1 receptor agonist PRE-084, inhibit the osmotic swelling of Müller cell somata induced by superfusion of rat retinal slices with a hypoosmotic solution containing barium ions. In contrast, PRE-084 did not inhibit the osmotic swelling of bipolar cell somata. The effects of σ receptor agonists on the Müller cell swelling were abrogated in the presence of blockers of metabotropic glutamate and purinergic P2Y1 receptors, respectively, suggesting that σ receptor activation triggers activation of a glutamatergic-purinergic signaling cascade which is known to prevent the osmotic Müller cell swelling. The swelling-inhibitory effect of 17β-estradiol was prevented by the σ1 receptor antagonist BD1047, suggesting that the effect is mediated by σ1 receptor activation. The data may suggest that the neuroprotective effect of σ receptor activation in the retina is in part mediated by prevention of the cytotoxic swelling of retinal glial cells.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Helge Winters
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany.
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Abstract
This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ1R) and sigma receptor two (σ2R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ1Rs are intracellular receptors acting as chaperone proteins that modulate Ca2+ signaling through the IP3 receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ1R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K+ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ1R modulation of Ca2+ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ1Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them.
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Affiliation(s)
- Colin G Rousseaux
- a Department of Pathology and Laboratory Medicine , University of Ottawa , Ottawa , ON , Canada and
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Mavlyutov TA, Epstein M, Guo LW. Subcellular localization of the sigma-1 receptor in retinal neurons - an electron microscopy study. Sci Rep 2015; 5:10689. [PMID: 26033680 PMCID: PMC4649997 DOI: 10.1038/srep10689] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 04/27/2015] [Indexed: 11/09/2022] Open
Abstract
The Sigma-1 receptor (S1R) is known to play a protective role in the central nervous system including the retina. A major barrier for understanding the underlying mechanism is an ambiguity of S1R subcellular localizations. We thus conducted the first electron microscopy (EM) study of S1R subcellular distribution in the mouse retina. Immuno-EM imaging showed previously under-appreciated S1R presence in photoreceptor cells. Unlike in other cell types in previous reports, in photoreceptor cells S1R was found in the nuclear envelope but not localized in the endoplasmic reticulum (ER), raising a possibility of S1R-mediated modulatory mechanisms different than conventionally thought. While in bipolar cells S1R was detected only in the nuclear envelope, in ganglion cells S1R was identified predominantly in the nuclear envelope and found in the ER as well. A predominant localization of S1R in the nuclear envelope in all three retinal neurons implicates a potential role of S1R in modulating nuclear activities. Moreover, its absence in the plasma membrane and presence in the subsurface ER cisternae that are juxtaposed to the plasma membrane in ganglion cells may lend mechanistic insights generally important for frequently reported S1R modulations of ion channels in neurons.
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Affiliation(s)
- Timur A. Mavlyutov
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, Madison, WI 53705, USA
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, Madison, WI 53705, USA
| | - Miles Epstein
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, 41 Bardeen Medical Laboratory, 470 N Charter Street, Madison, WI 53706, USA
| | - Lian-Wang Guo
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, Madison, WI 53705, USA
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, 5151 Wisconsin Institute for Medical Research, 1111 Highland Ave, Madison, WI 53705, USA
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13
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Shanmugam A, Wang J, Markand S, Perry RL, Tawfik A, Zorrilla E, Ganapathy V, Smith SB. Sigma receptor 1 activation attenuates release of inflammatory cytokines MIP1γ, MIP2, MIP3α, and IL12 (p40/p70) by retinal Müller glial cells. J Neurochem 2015; 132:546-58. [PMID: 25439327 PMCID: PMC4451448 DOI: 10.1111/jnc.13002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 11/25/2014] [Indexed: 12/27/2022]
Abstract
The high-affinity sigma receptor 1 (σR1) ligand (+)-pentazocine ((+)-PTZ) affords profound retinal neuroprotection in vitro and in vivo by a yet-unknown mechanism. A common feature of retinal disease is Müller cell reactive gliosis, which includes cytokine release. Here, we investigated whether lipopolysaccharide (LPS) stimulates cytokine release by primary mouse Müller cells and whether (+)-PTZ alters release. Using a highly sensitive inflammatory antibody array we observed significant release of macrophage inflammatory proteins (MIP1γ, MIP2, MIP3α) and interleukin-12 (IL12 (p40/p70)) in LPS-treated cells compared to controls, and a significant decrease in secretion upon (+)-PTZ treatment. Müller cells from σR1 knockout mice demonstrated increased MIP1γ, MIP2, MIP3α and IL12 (p40/p70) secretion when exposed to LPS compared to LPS-stimulated WT cells. We investigated whether cytokine secretion was accompanied by cytosolic-to-nuclear NFκB translocation and whether endothelial cell adhesion/migration was altered by released cytokines. Cells exposed to LPS demonstrated increased NFκB nuclear location, which was reduced significantly in (+)-PTZ-treated cells. Media conditioned by LPS-stimulated-Müller cells induced leukocyte-endothelial cell adhesion and endothelial cell migration, which was attenuated by (+)-PTZ treatment. The findings suggest that release of certain inflammatory cytokines by Müller cells can be attenuated by σR1 ligands providing insights into the retinal neuroprotective role of this receptor.
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Affiliation(s)
- Arul Shanmugam
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
| | - Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
| | - Shanu Markand
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
| | - Richard L Perry
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
| | - Amany Tawfik
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
| | - Eric Zorrilla
- Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, California, USA
| | - Vadivel Ganapathy
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
- James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, USA
- Department of Ophthalmology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, USA
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Ha Y, Shanmugam AK, Markand S, Zorrilla E, Ganapathy V, Smith SB. Sigma receptor 1 modulates ER stress and Bcl2 in murine retina. Cell Tissue Res 2014; 356:15-27. [PMID: 24469320 PMCID: PMC3976706 DOI: 10.1007/s00441-013-1774-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 11/18/2013] [Indexed: 01/08/2023]
Abstract
Sigma receptor 1 (σR1), a non-opiate transmembrane protein located on endoplasmic reticulum (ER) and mitochondrial membranes, is considered to be a molecular chaperone. Marked protection against cell death has been observed when ligands for σR1 have been used in in vitro and in vivo models of retinal cell death. Mice lacking σR1 (σR1(-/-)) manifest late-onset loss of retinal ganglion cells and retinal electrophysiological changes (after many months). The role of σR1 in the retina and the mechanisms by which its ligands afford neuroprotection are unclear. We therefore used σR1(-/-) mice to investigate the expression of ER stress genes (BiP/GRP78, Atf6, Atf4, Ire1α) and proteins involved in apoptosis (BCL2, BAX) and to examine the retinal transcriptome at young ages. Whereas no significant changes occurred in the expression of major ER stress genes (over a period of a year) in neural retina, marked changes were observed in these genes, especially Atf6, in isolated retinal Müller glial cells. BCL2 levels decreased in σR1(-/-) retina concomitantly with decreases in NFkB and pERK1/2. We postulate that σR1 regulates ER stress in retinal Müller cells and that the role of σR1 in retinal neuroprotection probably involves BCL2 and some of the proteins that modify its expression (such as ERK, NFκB). Data from the analysis of the retinal transcriptome of σR1 null mice provide new insights into the role of σR1 in retinal neuroprotection.
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Affiliation(s)
- Yonju Ha
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, GA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, GA
| | - Arul K. Shanmugam
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, GA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, GA
| | - Shanu Markand
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, GA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, GA
| | - Eric Zorrilla
- Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, CA
| | - Vadivel Ganapathy
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, GA
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, GA
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, GA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, GA
- Department of Ophthalmology, Medical College of Georgia, Georgia Regents University, Augusta, GA
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Li Z, He T, Du K, Xing YQ, Run YM, Yan Y, Shen Y. Inhibition of oxygen-induced ischemic retinal neovascularization with adenoviral 15-lipoxygenase-1 gene transfer via up-regulation of PPAR-γ and down-regulation of VEGFR-2 expression. PLoS One 2014; 9:e85824. [PMID: 24465728 PMCID: PMC3897531 DOI: 10.1371/journal.pone.0085824] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 12/02/2013] [Indexed: 12/13/2022] Open
Abstract
15-lipoxygenase-1 (15-LOX-1) plays an important role in angiogenesis, but how it works still remains a controversial subject. The aims of our study are focused on determining whether or not 15-LOX-1 inhibiting oxygen-induced ischemic retinal neovascularization (RNV) and the underlying regulatory mechanism involving of 15-LOX-1, peroxisome proliferator-activated receptor γ (PPAR-γ) and vascular endothelial growth factor receptor 2 (VEGFR-2) in oxygen-induced retinopathy (OIR). Recombinant adenoviral vectors that expressing the 15-LOX-1 gene (Ad-15-LOX-1-GFP) or the green fluorescence protein gene (Ad-GFP) were intravitreous injected into the OIR mice at postnatal day 12 (P12), the mice were sacrificed 5 days later (P17). Retinal 15-LOX-1 expression was significantly increased at both mRNA and protein levels after 15-LOX-1 gene transfer. Immunofluorescence staining of retinal sections revealed 15-LOX-1 expression was primarily in the outer plexiform layer (OPL), inner nuclear layer (INL) and ganglion cell layer (GCL) retina. Meanwhile, RNV was significantly inhibited indicated by fluorescein retinal angiography and quantification of the pre-retinal neovascular cells. The expression levels of PPAR-γ were significantly up-regulated while VEGFR-2 were significantly down-regulated both in mRNA and protein levels. Our results suggested 15-LOX-1 gene transfer inhibited RNV in OIR mouse model via up-regulation of PPAR-γ and further down-regulation of VEGFR-2 expression. This could be a potentially important regulatory mechanism involving 15-LOX-1, PPAR-γ and VEGFR-2 during RNV in OIR. In conclusion, 15-LOX-1 may be a new therapeutic target for treating neovascularization diseases.
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Affiliation(s)
- Zhi Li
- Eye Center, Renmin Hospital of Wuhan University, Eye Institute of Wuhan University, Wuhan, Hubei, China
- Department of Ophthalmology, Hospital Affiliated to Hubei University of Arts and Science, Xiangyang Central Hospital, Xiangyang, Hubei, China
| | - Tao He
- Eye Center, Renmin Hospital of Wuhan University, Eye Institute of Wuhan University, Wuhan, Hubei, China
| | - Ke Du
- Department of Oncology, Hospital Affiliated to Hubei University of Arts and Science, Xiangyang Central Hospital, Xiangyang, Hubei, China
| | - Yi-Qiao Xing
- Eye Center, Renmin Hospital of Wuhan University, Eye Institute of Wuhan University, Wuhan, Hubei, China
- * E-mail: (YQX); (YS)
| | - Yuan-Min Run
- Clinical Laboratory, Hospital Affiliated to Hubei University of Arts and Science, Xiangyang Central Hospital, Xiangyang, Hubei, China
| | - Ying Yan
- Department of Ophthalmology, Wuhan General Hospital of Guangzhou Military, Wuhan, Hubei, China
| | - Yin Shen
- Eye Center, Renmin Hospital of Wuhan University, Eye Institute of Wuhan University, Wuhan, Hubei, China
- * E-mail: (YQX); (YS)
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16
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Wang L, Deng QQ, Wu XH, Yu J, Yang XL, Zhong YM. Upregulation of glutamate-aspartate transporter by glial cell line-derived neurotrophic factor ameliorates cell apoptosis in neural retina in streptozotocin-induced diabetic rats. CNS Neurosci Ther 2013; 19:945-53. [PMID: 23870489 DOI: 10.1111/cns.12150] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 06/04/2013] [Accepted: 06/11/2013] [Indexed: 11/28/2022] Open
Abstract
AIMS Dysfunction of glutamate uptake, largely mediated by the glutamate-aspartate transporter (GLAST), may lead to retinal cell apoptosis in diabetic retinopathy. The aim of this study is to examine how cell apoptosis and the expression level of GLAST in neural retina of a diabetic rat model are changed and whether the neuroretinal apoptosis could be ameliorated by the administration of glial cell line-derived neurotrophic factor (GDNF). METHODS Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) in Sprague-Dawley rats. GLAST protein expression levels were determined by Western blotting, whereas apoptosis of retinal neurons was evaluated by TUNEL staining. To assess the role of GDNF in ameliorating the STZ-induced retinal changes, GDNF/GDNF with siRNA directed against GLAST was injected into the vitreous after STZ injection. RESULTS In rat retinas 4 weeks after the onset of STZ-induced diabetes, TUNEL-positive cells were significantly increased, whereas GLAST levels were significantly reduced. Intraocular administration of GDNF at the early stage of diabetes remarkably increased the GLAST levels and decreased TUNEL-positive signals in the retinas. These effects of GDNF were largely abolished by coadministration of GLAST siRNA. CONCLUSIONS GDNF, administrated at the early stage of diabetes, could rescue retinal cells from neurodegeneration by upregulating the expression of GLAST.
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Affiliation(s)
- Lu Wang
- Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
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17
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Fan W, Xing Y, Zhong Y, Chen C, Shen Y. Expression of NMDA receptor subunit 1 in the rat retina. Acta Histochem 2013; 115:42-7. [PMID: 22512920 DOI: 10.1016/j.acthis.2012.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Revised: 03/21/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) belong to the ionotropic glutamate receptors, which play key roles in neuronal communication in the retina. NMDA receptors are tetrameric protein complexes usually comprising two obligatory NMDA receptor 1 (NR1) subunits and modulatory NMDA receptor 2/3 (NR2/3) subunits. Although the expression patterns of different NMDA receptor subunits have been extensively studied, in this study we focused on NR1 protein expression in the rat retina by immunofluorescence double labeling. We show that NR1 labeling is diffusely distributed in the outer plexiform layer (OPL) and throughout the whole inner plexiform layer (IPL). The NR1-immunoreactivity (IR) was displayed in a variety of cells in the inner nuclear layer (INL) and the ganglion cell layer (GCL). Interestingly, NR1 was expressed in both rod and cone bipolar cells identified by specific bipolar cell markers Chx10, protein kinase C (PKC) and recoverin. All the amacrine cells that we studied, including cholinergic, dopaminergic, GABAergic and glycinergic amacrine cells, were NR1-IR positive. In the ganglion cell layer, NR1-IR was expressed in all cells that were positive for the ganglion cell marker Brn3a. Our study suggests that the NR1 subunit is expressed more widely than was previously appreciated.
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18
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Zhang PP, Yang XL, Zhong YM. Cellular localization of P2Y₆ receptor in rat retina. Neuroscience 2012; 220:62-9. [PMID: 22728100 DOI: 10.1016/j.neuroscience.2012.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 06/08/2012] [Accepted: 06/13/2012] [Indexed: 12/23/2022]
Abstract
Extracellular nucleotides exert their actions via two subfamilies of purinoceptors: P2X and P2Y. Eight mammalian P2Y receptor subtypes (P2Y(1,2,4,6,11,12,13,14)) have been identified. In this work, the localization of P2Y(6) was studied in rat retina using double immunofluorescence labeling and confocal scanning microscopy. Immunostaining for P2Y(6) was strong in the outer plexiform layer and was diffusely distributed throughout the full thickness of the inner plexiform layer. In addition, P2Y(6) immunoreactivity was clearly observed in many cells in the inner nuclear layer and the ganglion cell layer. In the outer retina photoreceptor terminals, labeled by VGluT1, and horizontal cells, labeled by calbindin, were P2Y(6)-positive. However, no P2Y(6) immunostaining was detected in bipolar cells, labeled by homeobox protein Chx10. In the inner retina P2Y(6) was localized to most of GABAergic amacrine cells, including dopaminergic and cholinergic ones, stained by tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) respectively. Some of glycinergic amacrine cells, but not glycinergic AII amacrine cells, were also labeled by P2Y(6). Moreover, P2Y(6) immunoreactivity was seen in almost all ganglion cells, labeled by Brn3a. In Müller glial cells, stained by cellular retinaldehyde binding protein (CRALBP), however, no P2Y(6) expression was found in both somata and processes. We speculate that P2Y(6) may be involved in retinal information processing in different ways, probably by regulating the release of transmitters and/or modulating the radial flow of visual signals and lateral interaction mediated by horizontal and amacrine cells.
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Affiliation(s)
- P P Zhang
- Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, PR China
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19
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Sun X, Cheng F, Meng B, Yang B, Song W, Yuan H. Pregnenolone sulfate decreases intraocular pressure and changes expression of sigma receptor in a model of chronic ocular hypertension. Mol Biol Rep 2012; 39:6607-14. [PMID: 22311017 DOI: 10.1007/s11033-012-1491-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 01/24/2012] [Indexed: 11/24/2022]
Abstract
Sigma receptors are Ca(2+)-sensitive, ligand-operated receptor chaperones at the mitochondrion-associated endoplasmic reticulum membrane. This study describes the effect of the sigma receptor 1 agonist pregnenolone sulfate on intraocular pressure (IOP) and sigma receptor 1 expression in rat retinas after chronic ocular hypertension. Chronic ocular hypertension was induced by occlusion of episcleral veins. Retinal histological sections were obtained to determine inner plexiform layer thickness and the number of cell bodies in the ganglion cell layer. Sigma receptor expression in rat retinas was analyzed by RT-PCR and Western blotting. Cauterization caused IOP to increase >73%, and the pressure was maintained for 2 months. A time-dependent loss of ganglion cells and retinal thickness occurred at elevated IOP. High IOP decreased sigma receptor 1 expression during the first week, but expression was increased at 8 weeks. Injected pregnenolone significantly decreased IOP, prevented ganglion cell loss, protected inner plexiform layer thickness, and increased sigma receptor 1 expression in episcleral vein-cauterized rats. Sigma receptors appear to be neuroprotective and potential targets for glaucoma therapeutics.
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Affiliation(s)
- Xian Sun
- Key Laboratory of Ophthalmology, Department of Ophthalmology, The 2nd Affiliated Hospital, Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
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20
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Wu XH, Deng QQ, Jiang SX, Yang XL, Zhong YM. Distribution of somatostatin receptor 5 in mouse and bullfrog retinas. Peptides 2012; 33:291-7. [PMID: 22244811 DOI: 10.1016/j.peptides.2011.12.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 12/30/2011] [Accepted: 12/30/2011] [Indexed: 01/21/2023]
Abstract
Somatostatin (SRIF), as a neuroactive peptide in the CNS, may act as a neuromodulator through activation of five specific receptor subtypes (sst(1)-sst(5)). In this work we conducted a comparative study of the expression of sst(5) in mouse and bullfrog retinas by immunofluorescence double labeling. Basically, the expression profiles of sst(5) in the retinas of the two species were similar. That is, in the inner retina sst(5) was localized to dopaminergic and cholinergic amacrine cells, stained by tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) respectively, and cells in the ganglion cell layer, whereas in the outer retina immunostaining for sst(5) was observed in horizontal cells. However, a more widespread, abundant distribution of labeling for sst(5), as compared to mouse retina, was seen in bullfrog retina: strong labeling for sst(5) was diffusely distributed in both outer and inner plexiform layers (OPL and IPL) in the bullfrog retina, but the labeling was only observed in the IPL of the mouse retina. In addition, bullfrog photoreceptors, both rods and cones, but not mouse ones, were labeled by sst(5). In combination with the experiments showing that SRIF-immunoreactivity was mainly found in the inner retina, our results suggest that SRIF, released from SRIF-containing cells in the inner retina, may play a neuromodulatory role in both outer and inner retina mediated by volume transmission via sst(5) in bullfrog retina, while the SRIF action may be largely restricted to the mouse inner retina.
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Affiliation(s)
- Xiao-Hua Wu
- Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
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21
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Ha Y, Saul A, Tawfik A, Williams C, Bollinger K, Smith R, Tachikawa M, Zorrilla E, Ganapathy V, Smith SB. Late-onset inner retinal dysfunction in mice lacking sigma receptor 1 (σR1). Invest Ophthalmol Vis Sci 2011; 52:7749-60. [PMID: 21862648 PMCID: PMC3183986 DOI: 10.1167/iovs.11-8169] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/11/2011] [Accepted: 08/11/2011] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Sigma receptor 1 (σR1) is expressed abundantly in the eye, and several reports suggest that this putative molecular chaperone plays a role in lens cell survival, control of intraocular pressure (IOP), and retinal neuroprotection. The present study examined the consequence of the absence of σR1 on ocular development, structure, and function. METHODS Wild-type (σR1⁺/⁺), heterozygous (σR1⁺/⁻), and homozygous (σR1⁻/⁻, knockout) mice aged 5 to 59 weeks were subjected to comprehensive electrophysiological testing and IOP measurement. The eyes were examined by light and electron microscopy and subjected to morphometric examination and detection of apoptosis. RESULTS Cornea and lens of σR1⁻/⁻ mice were similar to wild-type mice in morphologic appearance at all ages examined, and IOP was within normal limits. Comprehensive ERG and morphometric analyses initially yielded normal findings in the σR1⁻/⁻ mice compared with those in the wild-type. By 12 months, however, significantly decreased ERG b-wave amplitudes and diminished negative scotopic threshold responses, consistent with inner retinal dysfunction, were detected in σR1⁻/⁻ mice. Concomitant with these late-onset changes were increased TUNEL- and active caspase 3-positive cells in the inner retina and significant loss of cells in the ganglion cell layer, particularly in the central retina. Before these functional and structural abnormalities, there was ultrastructural evidence of axonal disruption in the optic nerve head of σR1⁻/⁻ mice as early as 6 months of age, although there were no alterations observed in retinal vascularization in σR1⁻/⁻ mice. CONCLUSIONS These data suggest that lack of σR1 leads to development of late-onset retinal dysfunction with similarities to optic neuropathy.
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Affiliation(s)
- Yonju Ha
- From the Departments of Cellular Biology and Anatomy
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Alan Saul
- Ophthalmology, and
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Amany Tawfik
- From the Departments of Cellular Biology and Anatomy
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Cory Williams
- From the Departments of Cellular Biology and Anatomy
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Kathryn Bollinger
- Ophthalmology, and
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Robert Smith
- From the Departments of Cellular Biology and Anatomy
| | - Masanori Tachikawa
- the Department of Pharmaceutics, University of Toyama, Toyama, Japan; and
| | - Eric Zorrilla
- the Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, California
| | - Vadivel Ganapathy
- Biochemistry and Molecular Biology, and
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
| | - Sylvia B. Smith
- From the Departments of Cellular Biology and Anatomy
- Ophthalmology, and
- the Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, Gerogia
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22
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Liu F, Xu G, Wang L, Jiang S, Yang X, Zhong Y. Gene expression and protein distribution of orexins and orexin receptors in rat retina. Neuroscience 2011; 189:146-55. [DOI: 10.1016/j.neuroscience.2011.04.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 03/18/2011] [Accepted: 04/04/2011] [Indexed: 12/24/2022]
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23
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Zhang XJ, Liu LL, Jiang SX, Zhong YM, Yang XL. Activation of the ζ receptor 1 suppresses NMDA responses in rat retinal ganglion cells. Neuroscience 2011; 177:12-22. [PMID: 21211548 DOI: 10.1016/j.neuroscience.2010.12.064] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 12/28/2010] [Accepted: 12/29/2010] [Indexed: 12/30/2022]
Abstract
The sigma receptor 1 (σR1) has been shown to modulate the activity of several voltage- and ligand-gated channels. Using patch-clamp techniques in rat retinal slice preparations, we demonstrated that activation of σR1 by SKF10047 (SKF) or PRE-084 suppressed N-methyl-D-aspartate (NMDA) receptor-mediated current responses from both ON and OFF type ganglion cells (GCs), dose-dependently, and the effect could be blocked by the σR1 antagonist BD1047 or the σR antagonist haloperidol. The suppression by SKF of NMDA currents was abolished with pre-incubation of the G protein inhibitor GDP-β-S or the Gi/o activator mastoparan. We further explored the intracellular signaling pathway responsible for the SKF-induced suppression of NMDA responses. Application of either cAMP/the PKA inhibitor Rp-cAMP or cGMP/the PKG inhibitor KT5823 did not change the SKF-induced effect, suggesting the involvement of neither cAMP/PKA nor cGMP/PKG pathway. In contrast, suppression of NMDA responses by SKF was abolished by internal infusion of the phosphatidylinostiol-specific phospholipase C (PLC) inhibitor U73122, but not by the phosphatidylcholine-PLC inhibitor D609. SKF-induced suppression of NMDA responses was dependent on intracellular Ca2+ concentration ([Ca2+]i), as evidenced by the fact that the effect was abolished when [Ca2+]i was buffered with 10 mM BAPTA. The SKF effect was blocked by xestospongin-C/heparin, IP3 receptor antagonists, but unchanged by ryanodine/caffeine, ryanodine receptor modulators. Furthermore, application of protein kinase C inhibitors Bis IV and Gö6976 eliminated the SKF effect. These results suggest that the suppression of NMDA responses of rat retinal GCs caused by the activation of σR1 may be mediated by a distinct [Ca2+]i-dependent PLC-PKC pathway. This effect of SKF could help ameliorate malfunction of GCs caused by excessive stimulation of NMDA receptors under pathological conditions.
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Affiliation(s)
- X-J Zhang
- Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Fudan University, 138 Yixueyuan Road, Shanghai 200032, PR China
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Zhang XJ, Liu LL, Wu Y, Jiang SX, Zhong YM, Yang XL. Sigma Receptor 1 Is Preferentially Involved in Modulation of N-Methyl- D-Aspartate Receptor-Mediated Light-Evoked Excitatory Postsynaptic Currents in Rat Retinal Ganglion Cells. Neurosignals 2011; 19:110-6. [DOI: 10.1159/000326784] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 02/25/2011] [Indexed: 11/19/2022] Open
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