1
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Chen Y, Yang X, Mao J. The Neuroprotective Effect of Activation of Sigma-1 Receptor on Neural Injury by Optic Nerve Crush. Invest Ophthalmol Vis Sci 2023; 64:9. [PMID: 37669061 PMCID: PMC10484044 DOI: 10.1167/iovs.64.12.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/09/2023] [Indexed: 09/06/2023] Open
Abstract
Purpose This study aimed to explore the neuroprotective effects of sigma-1 receptor (S1R) on optic nerve crush (ONC) mice by upregulating its expression through intravitreal injection of adeno-associated virus (AAV). Methods The animals were divided into four groups. Mice that underwent ONC were administered an intravitreal injection with blank vector (ONC group), with AAV targeting downregulation of S1R (S1R-sh group), or with AAV targeting overexpression of S1R (S1R-AAV group). Mice in the control group underwent intravitreal injection with blank vector. The thickness of each layer of the retina was measured through optical coherence tomography, and the apoptotic rate of retinal neurons was determined using the TUNEL assay. The expression levels of brain-derived neurotrophic factor (BDNF) and S1R were quantified through western blot. Electroretinogram (ERG) was performed to evaluate the visual function. Results The thickness of the total retina (P = 0.001), ganglion cell layer (P = 0.017), and inner nuclear layer (P = 0.002) in S1R-AAV group was significantly thicker than that of the ONC group. The number of retinal apoptotic cells in the S1R-AAV group was 23% lower than that in the ONC group (P = 0.002). ERG results showed that, compared to the ONC group, the amplitudes of the a- and b-waves were higher in the S1R-AAV group (a-wave, P < 0.001; b-wave, P = 0.007). Western blot showed that the expression of BDNF in the S1R-AAV group was higher than that in the ONC group (P < 0.001). Conclusions Activation of S1R in the retina through intravitreal injection of AAV can effectively maintain the retina structure, promote neuronal cell survival, and protect visual function.
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Affiliation(s)
- Yao Chen
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- Hunan Key Laboratory of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Chang Sha, China
| | - Xueli Yang
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- Hunan Key Laboratory of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Chang Sha, China
| | - Junfeng Mao
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- Hunan Key Laboratory of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Chang Sha, China
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2
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Wang J, Barwick SR, Xiao H, Smith SB. Evaluation of the role of Sigma 1 receptor and Cullin3 in retinal photoreceptor cells. Free Radic Biol Med 2023; 205:214-223. [PMID: 37328017 PMCID: PMC10527355 DOI: 10.1016/j.freeradbiomed.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/24/2023] [Accepted: 06/13/2023] [Indexed: 06/18/2023]
Abstract
Sigma 1 receptor (Sig1R), a pluripotent modulator of cell survival, is neuroprotective in models of retinal degeneration when activated by the high-affinity, high-specificity ligand (+)-pentazocine ((+)-PTZ). The molecular mechanisms of Sig1R-mediated retinal neuroprotection are under investigation. We previously reported that the antioxidant regulatory transcription factor Nrf2 may be involved in Sig1R-mediated retinal photoreceptor cell (PRC) rescue. Cullin 3 (Cul3) is a component of the Nrf2-Keap1 antioxidant pathway and facilitates Nrf2 ubiquitination. Our earlier transcriptome analysis revealed decreased Cul3 in retinas lacking Sig1R. Here, we asked whether Sig1R activation can modulate Cul3 expression in 661 W cone PRCs. Proximity ligation and co-immunoprecipitation (co-IP) showed that Cul3 resides closely to and co-IPs with Sig1R. Activation of Sig1R using (+)-PTZ significantly increased Cul3 at the gene/protein level; silencing Sig1R decreased Cul3 gene/protein levels. Experiments in which Cul3 was silenced in cells exposed to tBHP resulted in increased oxidative stress, which was not attenuated with Sig1R activation by (+)-PTZ, whereas cells transfected with scrambled siRNA (and incubated with tBHP) responded to (+)-PTZ treatment by decreasing levels of oxidative stress. Assessment of mitochondrial respiration and glycolysis revealed significantly improved maximal respiration, spare capacity and glycolytic capacity in oxidatively-stressed cells transfected with scrambled siRNA and treated with (+)-PTZ, but not in (+)-PTZ treated, oxidatively-stressed cells in which Cul3 had been silenced. The data provide the first evidence that Sig1R co-localizes/interacts with Cul3, a key player in the Nrf2-Keap1 antioxidant pathway. The data suggest that the preservation of mitochondrial respiration/glycolytic function and reduction of oxidative stress observed upon activation of Sig1R occur in part in a Cul3-dependent manner.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Shannon R Barwick
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Haiyan Xiao
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA.
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3
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Wang T, Jia H. The Sigma Receptors in Alzheimer's Disease: New Potential Targets for Diagnosis and Therapy. Int J Mol Sci 2023; 24:12025. [PMID: 37569401 PMCID: PMC10418732 DOI: 10.3390/ijms241512025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/14/2023] [Accepted: 07/16/2023] [Indexed: 08/13/2023] Open
Abstract
Sigma (σ) receptors are a class of unique proteins with two subtypes: the sigma-1 (σ1) receptor which is situated at the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM), and the sigma-2 (σ2) receptor, located in the ER-resident membrane. Increasing evidence indicates the involvement of both σ1 and σ2 receptors in the pathogenesis of Alzheimer's disease (AD), and thus these receptors represent two potentially effective biomarkers for emerging AD therapies. The availability of optimal radioligands for positron emission tomography (PET) neuroimaging of the σ1 and σ2 receptors in humans will provide tools to monitor AD progression and treatment outcomes. In this review, we first summarize the significance of both receptors in the pathophysiology of AD and highlight AD therapeutic strategies related to the σ1 and σ2 receptors. We then survey the potential PET radioligands, with an emphasis on the requirements of optimal radioligands for imaging the σ1 or σ2 receptors in humans. Finally, we discuss current challenges in the development of PET radioligands for the σ1 or σ2 receptors, and the opportunities for neuroimaging to elucidate the σ1 and σ2 receptors as novel biomarkers for early AD diagnosis, and for monitoring of disease progression and AD drug efficacy.
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Affiliation(s)
- Tao Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
- Department of Nuclear Medicine, Xinqiao Hospital, Army Medical University, Chongqing 400037, China
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
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4
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Zhao J, Veeranan-Karmegam R, Baker FC, Mysona BA, Bagchi P, Liu Y, Smith SB, Gonsalvez GB, Bollinger KE. Defining the ligand-dependent proximatome of the sigma 1 receptor. Front Cell Dev Biol 2023; 11:1045759. [PMID: 37351276 PMCID: PMC10284605 DOI: 10.3389/fcell.2023.1045759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 05/16/2023] [Indexed: 06/24/2023] Open
Abstract
Sigma 1 Receptor (S1R) is a therapeutic target for a wide spectrum of pathological conditions ranging from neurodegenerative diseases to cancer and COVID-19. S1R is ubiquitously expressed throughout the visceral organs, nervous, immune and cardiovascular systems. It is proposed to function as a ligand-dependent molecular chaperone that modulates multiple intracellular signaling pathways. The purpose of this study was to define the S1R proximatome under native conditions and upon binding to well-characterized ligands. This was accomplished by fusing the biotin ligase, Apex2, to the C terminus of S1R. Cells stably expressing S1R-Apex or a GFP-Apex control were used to map proximal proteins. Biotinylated proteins were labeled under native conditions and in a ligand dependent manner, then purified and identified using quantitative mass spectrometry. Under native conditions, S1R biotinylates over 200 novel proteins, many of which localize within the endomembrane system (endoplasmic reticulum, Golgi, secretory vesicles) and function within the secretory pathway. Under conditions of cellular exposure to either S1R agonist or antagonist, results show enrichment of proteins integral to secretion, extracellular matrix formation, and cholesterol biosynthesis. Notably, Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) displays increased binding to S1R under conditions of treatment with Haloperidol, a well-known S1R antagonist; whereas Low density lipoprotein receptor (LDLR) binds more efficiently to S1R upon treatment with (+)-Pentazocine ((+)-PTZ), a classical S1R agonist. Furthermore, we demonstrate that the ligand bound state of S1R correlates with specific changes to the cellular secretome. Our results are consistent with the postulated role of S1R as an intracellular chaperone and further suggest important and novel functionalities related to secretion and cholesterol metabolism.
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Affiliation(s)
- Jing Zhao
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta, GA, United States
| | - Rajalakshmi Veeranan-Karmegam
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Frederick C. Baker
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Barbara A. Mysona
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University, Atlanta, GA, United States
| | - Yutao Liu
- Culver Vision Discovery Institute, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Sylvia B. Smith
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Graydon B. Gonsalvez
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Kathryn E. Bollinger
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Culver Vision Discovery Institute, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States
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5
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Munguia-Galaviz FJ, Miranda-Diaz AG, Cardenas-Sosa MA, Echavarria R. Sigma-1 Receptor Signaling: In Search of New Therapeutic Alternatives for Cardiovascular and Renal Diseases. Int J Mol Sci 2023; 24:ijms24031997. [PMID: 36768323 PMCID: PMC9916216 DOI: 10.3390/ijms24031997] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
Cardiovascular and renal diseases are among the leading causes of death worldwide, and regardless of current efforts, there is a demanding need for therapeutic alternatives to reduce their progression to advanced stages. The stress caused by diseases leads to the activation of protective mechanisms in the cell, including chaperone proteins. The Sigma-1 receptor (Sig-1R) is a ligand-operated chaperone protein that modulates signal transduction during cellular stress processes. Sig-1R interacts with various ligands and proteins to elicit distinct cellular responses, thus, making it a potential target for pharmacological modulation. Furthermore, Sig-1R ligands activate signaling pathways that promote cardioprotection, ameliorate ischemic injury, and drive myofibroblast activation and fibrosis. The role of Sig-1R in diseases has also made it a point of interest in developing clinical trials for pain, neurodegeneration, ischemic stroke, depression in patients with heart failure, and COVID-19. Sig-1R ligands in preclinical models have significantly beneficial effects associated with improved cardiac function, ventricular remodeling, hypertrophy reduction, and, in the kidney, reduced ischemic damage. These basic discoveries could inform clinical trials for heart failure (HF), myocardial hypertrophy, acute kidney injury (AKI), and chronic kidney disease (CKD). Here, we review Sig-1R signaling pathways and the evidence of Sig-1R modulation in preclinical cardiac and renal injury models to support the potential therapeutic use of Sig-1R agonists and antagonists in these diseases.
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Affiliation(s)
- Francisco Javier Munguia-Galaviz
- Departamento de Fisiologia, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, Jalisco, Mexico
- Division de Ciencias de la Salud, Centro Universitario del Sur, Universidad de Guadalajara, Ciudad Guzman 49000, Jalisco, Mexico
| | - Alejandra Guillermina Miranda-Diaz
- Departamento de Fisiologia, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, Jalisco, Mexico
| | - Miguel Alejandro Cardenas-Sosa
- Departamento de Fisiologia, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara 44340, Jalisco, Mexico
| | - Raquel Echavarria
- CONACYT-Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara 44340, Jalisco, Mexico
- Correspondence:
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6
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Mysona BA, Zhao J, De Greef O, Beisel A, Patel PA, Berman L, Smith SB, Bollinger K. Sigma-1 receptor agonist, (+)-pentazocine, is neuroprotective in a Brown Norway rat microbead model of glaucoma. Exp Eye Res 2023; 226:109308. [PMID: 36400283 PMCID: PMC9839578 DOI: 10.1016/j.exer.2022.109308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/23/2022] [Accepted: 11/08/2022] [Indexed: 11/17/2022]
Abstract
PURPOSE Glaucoma is a worldwide leading cause of irreversible blindness. Standard treatments lower intraocular pressure (IOP). Novel treatments to prevent optic nerve (ON) degeneration are needed. Here, we investigate the hypothesis that sigma-1 receptor (S1R) agonist (+)-pentazocine (PTZ) is neuroprotective in a Brown Norway (BN) rat, microbead model of glaucoma. METHODS BN rats (9-11 weeks, male and female) were treated by intraperitoneal injection, 3 times per week with (+)-PTZ (2 mg/kg) or vehicle (VEH) alone. Treatment started 1 week prior to intraocular injection of polystyrene microbeads to elevate IOP. IOP was measured 2-3 times per week. Five weeks post microbead injection, rats were euthanized. ONs were removed, then fixed and processed for 63x oil, light microscope imaging of toluidine blue stained ON cross sections. To facilitate comparison of ON morphology from VEH and (+)-PTZ treated rats with similar ocular hypertensive insults, rats were assigned to low (IOP ≤15.8 mmHg), moderate (15.8 < IOP <28.0 mmHg), and high (IOP ≥28.0 mmHg) groups based on average IOP in the microbead injected eye. Axon numbers, axon density, axonal and glial areas, axon loss, and axon size distributions of naïve, bead, and contralateral ONs were assessed using QuPath program for automated image analysis. RESULTS (+)-PTZ treatment of BN rats protected ONs from damage caused by moderate IOP elevation. Treatment with (+)-PTZ significantly reduced axon loss and glial areas, and increased axon density and axonal areas compared to ONs from VEH treated rats with moderate IOP. (+)-PTZ-mediated neuroprotection was independent of IOP lowering effects. At average IOP ≥28.0 mmHg, (+)-PTZ treatment did not provide measurable neuroprotection. ONs from contralateral eyes exhibited subtle, complex changes in response to conditions in the bead eyes. CONCLUSIONS S1R agonist (+)-PTZ shows promise as a neuroprotective treatment for glaucoma. Future studies to understand the complex molecular mechanisms by which (+)-PTZ provides this neuroprotection are needed.
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Affiliation(s)
- Barbara A Mysona
- Department of Cellular Biology and Anatomy CB-2304, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA; James and Jean Culver Vision Discovery Institute, Department of Ophthalmology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
| | - Jing Zhao
- James and Jean Culver Vision Discovery Institute, Department of Ophthalmology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
| | - Oceane De Greef
- Student Training and Research Program, Graduate School, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
| | - August Beisel
- Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
| | - Parth A Patel
- Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
| | - Lindsay Berman
- Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy CB-2304, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
| | - Kathryn Bollinger
- James and Jean Culver Vision Discovery Institute, Department of Ophthalmology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
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7
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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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8
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Dalwadi DA, Kim S, Schetz J, Schreihofer DA, Kim S. Brain-derived neurotrophic factor for high-throughput evaluation of selective Sigma-1 receptor ligands. J Pharmacol Toxicol Methods 2022; 113:107129. [PMID: 34678430 PMCID: PMC9358981 DOI: 10.1016/j.vascn.2021.107129] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 01/03/2023]
Abstract
The Sigma-1 receptor (S1R) is an endoplasmic reticulum (ER) chaperone protein that has been implicated in attenuating inflammatory stress-mediated brain injuries. Selective S1R agonists represent a new class of therapeutic agent for treating neuropsychiatric and neurodegenerative disorders, however, to date, no S1R ligand has been approved for therapeutic purposes. We used three potential methods on known and potential S1R ligands to develop an unambiguous high-throughput cell screen for S1R activity. We screened known and potential S1R ligands using radioligand binding and previously reported markers of S1R activity including BDNF release, modulation of IP3 mediated calcium release, and modulation of NGF-induced neurite sprouting. Here, we present results several prototypical S1R compounds and some compounds with the potential for drug repurposing. Using an in-situ ELISA approach we demonstrated that these compounds could stimulate S1R-mediated BDNF release, which is a valuable therapeutic property since BDNF plays a critical role in neuronal support. These compounds were classified as S1R agonists because the BDNF response was comparable to the prototypical agonist 4-PPBP and because it could be reversed by a S1R selective concentration of the antagonist BD1063. When modulation of IP3 mediated calcium response and NGF-induced neurite sprouting were used as a measure of S1R activation, we were unable to reproduce the published results and determined that they are not reliable measures for evaluating functional properties of S1R ligands.
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Affiliation(s)
- Dhwanil A Dalwadi
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; Department of Medicine, Division of Gastroenterology, Oregon Health Sciences University, Portland, OR 97239, USA
| | - Stephanie Kim
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; University of Texas Medical Branch at Galveston, School of Medicine, Galveston, TX 77555, USA
| | - John Schetz
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Derek A Schreihofer
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Seongcheol Kim
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; Department of Cellular and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA.
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9
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Váczi S, Barna L, Harazin A, Mészáros M, Porkoláb G, Zvara Á, Ónody R, Földesi I, Veszelka S, Penke B, Fülöp L, Deli MA, Mezei Z. S1R agonist modulates rat platelet eicosanoid synthesis and aggregation. Platelets 2021; 33:709-718. [PMID: 34697991 DOI: 10.1080/09537104.2021.1981843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Sigma-1 receptor (S1R) is detected in different cell types and can regulate intracellular signaling pathways. S1R plays a role in the pathomechanism of diseases and the regulation of neurotransmitters. Fluvoxamine can bind to S1R and reduce the serotonin uptake of neurons and platelets. We therefore hypothesized that platelets express S1R, which can modify platelet function. The expression of the SIGMAR1 gene in rat platelets was examined with a reverse transcription polymerase chain reaction and a quantitative polymerase chain reaction. The receptor was also visualized by immunostaining and confocal laser scanning microscopy. The effect of S1R agonist PRE-084 on the eicosanoid synthesis of isolated rat platelets and ADP- and AA-induced platelet aggregation was examined. S1R was detected in rat platelets both at gene and protein levels. Pretreatment with PRE-084 of resting platelets induced elevation of eicosanoid synthesis. The rate of elevation in thromboxane B2 and prostaglandin D2 synthesis was similar, but the production of prostaglandin E2 was higher. The concentration-response curve showed a sigmoidal form. The most effective concentration of the agonist was 2 µM. PRE-084 increased the quantity of cyclooxygenase-1 as detected by ELISA. PRE-084 also elevated the ADP- and AA-induced platelet aggregation. S1R of platelets might regulate physiological or pathological functions.
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Affiliation(s)
- Sándor Váczi
- Department of Pathophysiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary.,Doctoral School of Theoretical Medicine, University of Szeged, Szeged, Hungary.,Gedeon Richter Talentum Foundation Scholarship, Budapest, Hungary
| | - L Barna
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - A Harazin
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - M Mészáros
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - G Porkoláb
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Á Zvara
- Institute of Genetics, Biological Research Centre, Szeged, Hungary
| | - R Ónody
- Department of Laboratory Medicine, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - I Földesi
- Department of Laboratory Medicine, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - S Veszelka
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - B Penke
- Department of Medical Chemistry, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - L Fülöp
- Department of Medical Chemistry, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - M A Deli
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Z Mezei
- Department of Pathophysiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary.,Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
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10
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Barbaraci C, Giurdanella G, Leotta CG, Longo A, Amata E, Dichiara M, Pasquinucci L, Turnaturi R, Prezzavento O, Cacciatore I, Zuccarello E, Lupo G, Pitari GM, Anfuso CD, Marrazzo A. Haloperidol Metabolite II Valproate Ester ( S)-(-)-MRJF22: Preliminary Studies as a Potential Multifunctional Agent Against Uveal Melanoma. J Med Chem 2021; 64:13622-13632. [PMID: 34477381 PMCID: PMC8474110 DOI: 10.1021/acs.jmedchem.1c00995] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Increased angiogenesis and vascular endothelial growth factor (VEGF) levels contribute to higher metastasis and mortality in uveal melanoma (UM), an aggressive malignancy of the eye in adults. (±)-MRJF22, a prodrug of the sigma (σ) ligand haloperidol metabolite II conjugated with the histone deacetylase (HDAC) inhibitor valproic acid, has previously demonstrated a promising antiangiogenic activity. Herein, the asymmetric synthesis of (R)-(+)-MRJF22 and (S)-(-)-MRJF22 was performed to investigate their contribution to (±)-MRJF22 antiangiogenic effects in human retinal endothelial cells (HREC) and to assess their therapeutic potential in primary human uveal melanoma (UM) 92-1 cell line. While both enantiomers displayed almost identical capabilities to reduce cell viability than the racemic mixture, (S)-(-)-MRJF22 exhibited the highest antimigratory effects in endothelial and tumor cells. Given the fundamental contribution of cell motility to cancer progression, (S)-(-)-MRJF22 may represent a promising candidate for novel antimetastatic therapy in patients with UM.
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Affiliation(s)
- Carla Barbaraci
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.,Vera Salus Ricerca S.r.l., Via Sigmund Freud 62/B, 96100 Siracusa, Italy
| | - Giovanni Giurdanella
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Via S. Sofia 97, 95123 Catania, Italy
| | | | - Anna Longo
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Via S. Sofia 97, 95123 Catania, Italy
| | - Emanuele Amata
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Maria Dichiara
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Lorella Pasquinucci
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Rita Turnaturi
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Orazio Prezzavento
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Ivana Cacciatore
- Department of Pharmacy, "G. D'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti Scalo, Italy
| | - Elisa Zuccarello
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, New York 10032, United States
| | - Gabriella Lupo
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Via S. Sofia 97, 95123 Catania, Italy
| | | | - Carmelina Daniela Anfuso
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Via S. Sofia 97, 95123 Catania, Italy
| | - Agostino Marrazzo
- Department of Drug and Health Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
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11
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Aishwarya R, Abdullah CS, Morshed M, Remex NS, Bhuiyan MS. Sigmar1's Molecular, Cellular, and Biological Functions in Regulating Cellular Pathophysiology. Front Physiol 2021; 12:705575. [PMID: 34305655 PMCID: PMC8293995 DOI: 10.3389/fphys.2021.705575] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/07/2021] [Indexed: 12/11/2022] Open
Abstract
The Sigma 1 receptor (Sigmar1) is a ubiquitously expressed multifunctional inter-organelle signaling chaperone protein playing a diverse role in cellular survival. Recessive mutation in Sigmar1 have been identified as a causative gene for neuronal and neuromuscular disorder. Since the discovery over 40 years ago, Sigmar1 has been shown to contribute to numerous cellular functions, including ion channel regulation, protein quality control, endoplasmic reticulum-mitochondrial communication, lipid metabolism, mitochondrial function, autophagy activation, and involved in cellular survival. Alterations in Sigmar1’s subcellular localization, expression, and signaling has been implicated in the progression of a wide range of diseases, such as neurodegenerative diseases, ischemic brain injury, cardiovascular diseases, diabetic retinopathy, cancer, and drug addiction. The goal of this review is to summarize the current knowledge of Sigmar1 biology focusing the recent discoveries on Sigmar1’s molecular, cellular, pathophysiological, and biological functions.
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Affiliation(s)
- Richa Aishwarya
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States
| | - Chowdhury S Abdullah
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States
| | - Mahboob Morshed
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States
| | - Naznin Sultana Remex
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States
| | - Md Shenuarin Bhuiyan
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States.,Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States
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12
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Barwick SR, Siddiq MS, Wang J, Xiao H, Marshall B, Perry E, Smith SB. Sigma 1 Receptor Co-Localizes with NRF2 in Retinal Photoreceptor Cells. Antioxidants (Basel) 2021; 10:antiox10060981. [PMID: 34205384 PMCID: PMC8234060 DOI: 10.3390/antiox10060981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/10/2021] [Accepted: 06/18/2021] [Indexed: 12/25/2022] Open
Abstract
Sigma 1 receptor (Sig1R), a modulator of cell survival, has emerged as a novel target for retinal degenerative disease. Studies have shown that activation of Sig1R, using the high affinity ligand (+)-pentazocine ((+)-PTZ), improves cone function in a severe retinopathy model. The rescue is accompanied by normalization of levels of NRF2, a key transcription factor that regulates the antioxidant response. The interaction of Sig1R with a number of proteins has been investigated; whether it interacts with NRF2, however, is not known. We used co-immunoprecipitation (co-IP), proximity ligation assay (PLA), and electron microscopy (EM) immunodetection methods to investigate this question in the 661W cone photoreceptor cell line. For co-IP experiments, immune complexes were precipitated by protein A/G agarose beads and immunodetected using anti-NRF2 antibody. For PLA, cells were incubated with anti-Sig1R polyclonal and anti-NRF2 monoclonal antibodies, then subsequently with (−)-mouse and (+)-rabbit PLA probes. For EM analysis, immuno-EM gold labeling was performed using nanogold-enhanced labeling with anti-NRF2 and anti-Sig1R antibodies, and data were confirmed using colloidal gold labeling. The co-IP experiment suggested that NRF2 was bound in a complex with Sig1R. The PLA assays detected abundant orange fluorescence in cones, indicating that Sig1R and NRF2 were within 40 nm of each other. EM immunodetection confirmed co-localization of Sig1R with NRF2 in cells and in mouse retinal tissue. This study is the first to report co-localization of Sig1R-NRF2 and supports earlier studies implicating modulation of NRF2 as a mechanism by which Sig1R mediates retinal neuroprotection.
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Affiliation(s)
- Shannon R. Barwick
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
| | - Mevish S. Siddiq
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
| | - Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
| | - Haiyan Xiao
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
| | - Brendan Marshall
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
| | - Elizabeth Perry
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA; (S.R.B.); (M.S.S.); (J.W.); (H.X.); (B.M.); (E.P.)
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912, USA
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
- Correspondence: ; Tel.: +1-706-721-7392; Fax: +1-706-721-6120
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13
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Wang J, Xiao H, Barwick S, Liu Y, Smith SB. Optimal timing for activation of sigma 1 receptor in the Pde6b rd10/J (rd10) mouse model of retinitis pigmentosa. Exp Eye Res 2021; 202:108397. [PMID: 33310057 PMCID: PMC7808329 DOI: 10.1016/j.exer.2020.108397] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/24/2020] [Accepted: 12/07/2020] [Indexed: 11/18/2022]
Abstract
Sigma 1 Receptor (Sig1R), a pluripotent modulator of cell survival, is a promising target for treatment of retinal degenerative diseases. Previously, we reported that administration of the high-affinity, high-specificity Sig1R ligand (+)-pentazocine, ((+)-PTZ) beginning at post-natal day 14 (P14) and continuing every other day improves visual acuity and delays loss of photoreceptor cells (PRCs) in the Pde6βrd10/J (rd10) mouse model of retinitis pigmentosa. Whether administration of (+)-PTZ, at time points concomitant with (P18) or following (P21, P24) onset of PRC death, would prove neuroprotective was investigated in this study. Rd10 mice were administered (+)-PTZ intraperitoneally [0.5 mg/kg], starting at either P14, P18, P21 or P24. Injections continued every other day through P42. Visual acuity was assessed using the optokinetic tracking response (OKR). Rd10 mice treated with (+)-PTZ beginning at P14 retained visual acuity for the duration of the study (~0.33 c/d at P21, ~0.38 c/d at P28, ~0.32 c/d at P35, ~0.32 c/d at P42), whereas mice injected beginning at P18, P21, P24 showed a decline in acuity when tested at P35 and P42. Their acuity was only slightly better than rd10-non-treated mice. Electrophysiologic function was assessed using scotopic and photopic electroretinography (ERG) to assess rod and cone function, respectively. Photopic a- and b-wave amplitudes were significantly greater in rd10 mice treated with (+)-PTZ beginning at P14 compared with non-treated mice and those in the later-onset (+)-PTZ injection groups. Retinal architecture was visualized in living mice using spectral domain-optical coherence tomography (SD-OCT) allowing measurement of the total retinal thickness, the inner retina and the outer retina (the area most affected in rd10 mice). The outer retina measured ~35 μm in rd10 mice treated with (+)-PTZ beginning at P14, which was significantly greater than mice in the later-onset (+)-PTZ injection groups (~25 μm) and non-treated rd10 mice (~25 μm). Following the visual function studies performed in the living mice, eyes were harvested at P42 for histologic analysis. While the inner retina was largely intact in all (+)-PTZ-injection groups, there was a marked reduction in the outer retina of non-treated rd10 mice (e.g. in the outer nuclear layer there were ~10 PRCs/100 μm retinal length). The rd10 mice treated with (+)-PTZ beginning at P14 had ~20 PRCs/100 μm retinal length, whereas the mice in groups beginning P18, P21 and P24 had ~16 PRCs/100 μm retinal length. In conclusion, the data indicate that delaying (+)-PTZ injection past the onset of PRC death in rd10 mice - even by a few days - can negatively impact the long-term preservation of retinal function. Our findings suggest that optimizing the administration of Sig1R ligands is critical for retinal neuroprotection.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Haiyan Xiao
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Shannon Barwick
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, United States.
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Xiao H, Wang J, Saul A, Smith SB. Comparison of Neuroprotective Effects of Monomethylfumarate to the Sigma 1 Receptor Ligand (+)-Pentazocine in a Murine Model of Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2020; 61:5. [PMID: 32150247 PMCID: PMC7401726 DOI: 10.1167/iovs.61.3.5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/24/2019] [Indexed: 12/20/2022] Open
Abstract
Purpose Activating the cell survival modulator sigma 1 receptor (Sig1R) delays cone photoreceptor cell loss in Pde6βrd10/J (rd10) mice, a model of retinitis pigmentosa. Beneficial effects are abrogated in rd10 mice lacking NRF2, implicating NRF2 as essential to Sig1R-mediated cone neuroprotection. Here we asked whether activation of NRF2 alone is sufficient to rescue cones in rd10 mice. Methods Expression of antioxidant genes was evaluated in 661W cells and in mouse retinas after treatment with monomethylfumarate (MMF), a potent NRF2 activator. Rd10 mice were administered MMF (50 mg/kg) or the Sig1R ligand (+)-pentazocine (PTZ; 0.5 mg/kg) intraperitoneally (every other day, P14-42). Mice were evaluated for visual acuity (optokinetic tracking response), retinal function (electroretinography) and architecture (SD-OCT); histologic retinal sections were evaluated morphometrically. Results MMF treatment increased Nrf2, Nqo1, Cat, Sod1, and Hmox1 expression in vitro and in vivo. Visual acuity of (+)-PTZ-treated rd10 mice was similar to wild-type mice; however, MMF treatment did not alter acuity compared with nontreated rd10 mice. Cone electroretinography b-wave amplitudes were greater in PTZ-treated than nontreated or MMF-treated rd10 mice. SD-OCT assessment of retinal thickness was greater in (+)-PTZ-treated mice versus nontreated or MMF-treated rd10 mice. Morphometric assessment of the outer nuclear layer revealed approximately 18 cells/100 µm retinal length in (+)-PTZ-treated rd10 mice, but only approximately 10 to 12 cells/100 µm in MMF-treated and nontreated rd10 retinas. Conclusions Activation of NRF2 using MMF, at least at our dosing regimen, is insufficient to attenuate catastrophic photoreceptor damage characteristic of rd10 mice. The data prompt investigation of additional mechanisms involved in Sig1R-mediated retinal neuroprotection.
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Affiliation(s)
- Haiyan Xiao
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia,United States
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia,United States
| | - Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia,United States
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia,United States
| | - Alan Saul
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia,United States
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia,United States
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, Georgia,United States
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia,United States
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, Georgia,United States
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15
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Wang J, Saul A, Smith SB. Activation of Sigma 1 Receptor Extends Survival of Cones and Improves Visual Acuity in a Murine Model of Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2019; 60:4397-4407. [PMID: 31639826 PMCID: PMC6808049 DOI: 10.1167/iovs.19-27709] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/21/2019] [Indexed: 01/02/2023] Open
Abstract
Purpose Retinitis pigmentosa (RP), a retinal photoreceptor degeneration, typically affects rod function and subsequently cones. Activation of sigma 1 receptor (Sig1R) has been shown to preserve cone function through 6 weeks in the rd10 mouse model of RP, when mice were treated systemically with the Sig1R ligand (+)-pentazocine (PTZ). This study determined the extent to which cone function is preserved in rd10 mice when Sig1R is activated. Methods Rd10 mice were administered (+)-PTZ (alternate days beginning at postnatal day [P]14) over a period of 180 days. Mouse visual function and structure were measured in vivo using optokinetic tracking response, scotopic and photopic electroretinography plus photopic assessment using "natural" noise stimuli, and optical coherence tomography (OCT). Immunofluorescent methods were used to detect cones in retinal cryosections. Results Visual acuity was maintained in rd10(+)-PTZ-treated mice through P56, whereas rd10 nontreated mice showed marked decline by P28. Cone responses were detected in (+)-PTZ-treated mice through P60, which were more robust when tested with natural noise stimuli; cone responses were minimal in nontreated rd10 mice. OCT revealed significantly thicker retinas in (+)-PTZ-treated rd10 mice through P60 compared to nontreated mice. Cones were detected by immunofluorescence in (+)-PTZ-treated rd10 retinas through P120. Conclusions The extent to which cone rescue could be sustained in (+)-PTZ-treated rd10 mice was evaluated comprehensively, showing that activation of Sig1R is associated with prolonged visual acuity, extended detection of cone function, and detection of cones in retinal histologic sections. The data reflect promising long-term neuroprotection when Sig1R is activated.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Alan Saul
- 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
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States
- 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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16
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Wang J, Zhao J, Cui X, Mysona BA, Navneet S, Saul A, Ahuja M, Lambert N, Gazaryan IG, Thomas B, Bollinger KE, Smith SB. The molecular chaperone sigma 1 receptor mediates rescue of retinal cone photoreceptor cells via modulation of NRF2. Free Radic Biol Med 2019; 134:604-616. [PMID: 30743048 PMCID: PMC6619428 DOI: 10.1016/j.freeradbiomed.2019.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/01/2019] [Accepted: 02/01/2019] [Indexed: 01/11/2023]
Abstract
Sigma 1 receptor (Sig1R), a putative molecular chaperone, has emerged as a novel therapeutic target for retinal degenerative disease. Earlier studies showed that activation of Sig1R via the high-affinity ligand (+)-pentazocine ((+)-PTZ) induced profound rescue of cone photoreceptor cells in the rd10 mouse model of retinitis pigmentosa; however the mechanism of rescue is unknown. Improved cone function in (+)-PTZ-treated mice was accompanied by reduced oxidative stress and normalization of levels of NRF2, a transcription factor that activates antioxidant response elements (AREs) of hundreds of cytoprotective genes. Here, we tested the hypothesis that modulation of NRF2 is central to Sig1R-mediated cone rescue. Activation of Sig1R in 661W cone cells using (+)-PTZ induced dose-dependent increases in NRF2-ARE binding activity and NRF2 gene/protein expression, whereas silencing Sig1R significantly decreased NRF2 protein levels and increased oxidative stress, although (+)-PTZ did not disrupt NRF2-KEAP1 binding. In vivo studies were conducted to investigate whether, in the absence of NRF2, activation of Sig1R rescues cones. (+)-PTZ was administered systemically for several weeks to rd10/nrf2+/+ and rd10/nrf2-/- mice. Through post-natal day 42, cone function was significant in rd10/nrf2+/+, but minimal in rd10/nrf2-/- mice as indicated by electroretinographic recordings using natural noise stimuli, optical coherence tomography and retinal histological analyses. Immunodetection of cones was limited in (+)-PTZ-treated rd10/nrf2-/-, though considerable in (+)-PTZ-treated rd10/nrf2+/+mice. The data suggest that Sig1R-mediated cone rescue requires NRF2 and provide evidence for a previously-unrecognized relationship between these proteins.
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Affiliation(s)
- J Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - J Zhao
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - X Cui
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - B A Mysona
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - S Navneet
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - A Saul
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - M Ahuja
- Department of Pharmacology/Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - N Lambert
- Department of Pharmacology/Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - I G Gazaryan
- Department of Anatomy and Cell Biology, New York Medical College, Valhalla, NY, USA
| | - B Thomas
- Department of Pharmacology/Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - K E Bollinger
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - S B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA.
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Garg C, Sharma AK, Gupta A, Kumar P. Anisamido-Polyethylenimines as Efficient Nonviral Vectors for the Transport of Plasmid DNA to Sigma Receptor-Bearing Cells In Vitro. J Pharm Sci 2018; 108:1552-1558. [PMID: 30513318 DOI: 10.1016/j.xphs.2018.11.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/24/2018] [Accepted: 11/27/2018] [Indexed: 01/31/2023]
Abstract
Site-specific delivery of therapeutics promises better outcomes in the treatment of diseases. A small ligand, anisamide, has been shown to specifically bind sigma receptors highly overexpressed on prostate cancer cells, one of the leading cancers causing deaths worldwide. Here, anisamide-tethered polyethylenimine polymers (AP) have been synthesized and evaluated for their capability to transport nucleic acid across the cell membrane. A series of modified polymers (AP-1 to AP-4) was synthesized, physicochemically characterized, and evaluated for their transfection efficiency and cytotoxicity. Postconjugation, there was a marginal decrease in the buffering capacity; however, it did not diminish the ultimate objective of the study rather improved the transfection efficiency and decreased the cytotoxicity making these polymers as efficient and safe vectors for nucleic acid delivery. All the modified polymers displayed enhanced capability to deliver DNA inside the cells. Among the series, the modified polymer, AP-4 (10% attempted substitution), exhibited the highest transfection in HEK293 cells having abundant sigma receptors with minimal cytotoxicity. The projected polymer also showed complete protection of bound DNA against enzymatic degradation. Altogether, the results demonstrated targeting ability of the proposed polymers to deliver nucleic acid to sigma receptor-bearing cells in vitro.
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Affiliation(s)
- Charu Garg
- Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India; Department of Chemistry, Dyal Singh College, University of Delhi, Lodhi Road, New Delhi 110003, India
| | - Ashwani Kumar Sharma
- Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Alka Gupta
- Department of Chemistry, Dyal Singh College, University of Delhi, Lodhi Road, New Delhi 110003, India.
| | - Pradeep Kumar
- Nucleic Acids Research Laboratory, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India.
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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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Pena J, Dulger N, Singh T, Zhou J, Majeska R, Redenti S, Vazquez M. Controlled microenvironments to evaluate chemotactic properties of cultured Müller glia. Exp Eye Res 2018; 173:129-137. [PMID: 29753729 DOI: 10.1016/j.exer.2018.05.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 12/20/2022]
Abstract
Emerging therapies have begun to evaluate the abilities of Müller glial cells (MGCs) to protect and/or regenerate neurons following retina injury. The migration of donor cells is central to many reparative strategies, where cells must achieve appropriate positioning to facilitate localized repair. Although chemical cues have been implicated in the MGC migratory responses of numerous retinopathies, MGC-based therapies have yet to explore the extent to which external biochemical stimuli can direct MGC behavior. The current study uses a microfluidics-based assay to evaluate the migration of cultured rMC-1 cells (as model MGC) in response to quantitatively-controlled microenvironments of signaling factors implicated in retinal regeneration: basic Fibroblast Growth factor (bFGF or FGF2); Fibroblast Growth factor 8 (FGF8); Vascular Endothelial Growth Factor (VEGF); and Epidermal Growth Factor (EGF). Findings indicate that rMC-1 cells exhibited minimal motility in response to FGF2, FGF8 and VEGF, but highly-directional migration in response to EGF. Further, the responses were blocked by inhibitors of EGF-R and of the MAPK signaling pathway. Significantly, microfluidics data demonstrate that changes in the EGF gradient (i.e. change in EGF concentration over distance) resulted in the directional chemotactic migration of the cells. By contrast, small increases in EGF concentration, alone, resulted in non-directional cell motility, or chemokinesis. This microfluidics-enhanced approach, incorporating the ability both to modulate and asses the responses of motile donor cells to a range of potential chemotactic stimuli, can be applied to potential donor cell populations obtained directly from human specimens, and readily expanded to incorporate drug-eluting biomaterials and combinations of desired ligands.
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Affiliation(s)
- Juan Pena
- The City College of New York, Department of Biomedical Engineering, 160 Convent Ave., Steinman Hall ST-403D, New York, NY, 10031, USA
| | - Nihan Dulger
- The City College of New York, Department of Biomedical Engineering, 160 Convent Ave., Steinman Hall ST-403D, New York, NY, 10031, USA
| | - Tanya Singh
- The City College of New York, Department of Biomedical Engineering, 160 Convent Ave., Steinman Hall ST-403D, New York, NY, 10031, USA
| | - Jing Zhou
- Lehman College, Department of Biology, 250 Bedford Park Blvd, Bronx, NY, 10468, USA
| | - Robert Majeska
- The City College of New York, Department of Biomedical Engineering, 160 Convent Ave., Steinman Hall ST-403D, New York, NY, 10031, USA
| | - Stephen Redenti
- Lehman College, Department of Biology, 250 Bedford Park Blvd, Bronx, NY, 10468, USA; The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Maribel Vazquez
- The City College of New York, Department of Biomedical Engineering, 160 Convent Ave., Steinman Hall ST-403D, New York, NY, 10031, USA; The Graduate Center of the City University of New York, New York, NY, 10016, USA.
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20
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Navneet S, Cui X, Zhao J, Wang J, Kaidery NA, Thomas B, Bollinger KE, Yoon Y, Smith SB. Excess homocysteine upregulates the NRF2-antioxidant pathway in retinal Müller glial cells. Exp Eye Res 2018; 178:228-237. [PMID: 29608906 DOI: 10.1016/j.exer.2018.03.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/14/2018] [Accepted: 03/22/2018] [Indexed: 10/17/2022]
Abstract
This study evaluated the effects of elevated homocysteine (Hcy) on the oxidative stress response in retinal Müller glial cells. Elevated Hcy has been implicated in retinal diseases including glaucoma and optic neuropathy, which are characterized by retinal ganglion cell (RGC) loss. To understand the mechanisms of Hcy-induced RGC loss, in vitro and in vivo models have been utilized. In vitro isolated RGCs are quite sensitive to elevated Hcy levels, while in vivo murine models of hyperhomocysteinemia (HHcy) demonstrate a more modest RGC loss (∼20%) over a period of many months. This differential response to Hcy between isolated cells and the intact retina suggests that the retinal milieu invokes mechanisms that buffer excess Hcy. Oxidative stress has been implicated as a mechanism of Hcy-induced neuron loss and NRF2 is a transcription factor that plays a major role in regulating cytoprotective responses to oxidative stress. In the present study we investigated whether HHcy upregulates NRF2-mediated stress responses in Müller cells, the chief retinal glial cell responsible for providing trophic support to retinal neurons. Primary Müller cells were exposed to L-Hcy-thiolactone [50μM-10mM] and assessed for viability, reactive oxygen species (ROS), and glutathione (GSH) levels. Gene/protein levels of Nrf2 and levels of NRF2-regulated antioxidants (NQO1, CAT, SOD2, HMOX1, GPX1) were assessed in Hcy-exposed Müller cells. Unlike isolated RGCs, isolated Müller cells are viable over a wide range of Hcy concentrations [50 μM - 1 mM]. Moreover, when exposed to elevated Hcy, Müller cells demonstrate decreased oxidative stress and decreased ROS levels. GSH levels increased by ∼20% within 24 h exposure to Hcy. Molecular analyses revealed 2-fold increase in Nrf2 expression. Expression of antioxidant genes Nqo1, Cat, Sod2, Hmox1, Gpx1 increased significantly. The consequences of Hcy exposure were evaluated also in Müller cells harvested from Nrf2-/- mice. In contrast to WT Müller cells, in which oxidative stress decreased upon exposure to Hcy, the Nrf2-/- Müller cells showed a significant increase in oxidative stress. Our data suggest that at least during early stages of Hhcy, a cytoprotective response may be in place, mediated in part by NRF2 in Müller cells.
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Affiliation(s)
- Soumya Navneet
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Xuezhi Cui
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Jing Zhao
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States
| | - Navneet Ammal Kaidery
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Bobby Thomas
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Kathryn E Bollinger
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States; Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Yisang Yoon
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, United States; Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA, United States.
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21
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Zhao J, Mysona BA, Wang J, Gonsalvez GB, Smith SB, Bollinger KE. Sigma 1 receptor regulates ERK activation and promotes survival of optic nerve head astrocytes. PLoS One 2017; 12:e0184421. [PMID: 28898265 PMCID: PMC5595338 DOI: 10.1371/journal.pone.0184421] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 08/23/2017] [Indexed: 11/18/2022] Open
Abstract
The sigma 1 receptor (S1R) is a unique transmembrane protein that has been shown to regulate neuronal differentiation and cellular survival. It is expressed within several cell types throughout the nervous system and visceral organs, including neurons and glia within the eye. S1R ligands are therapeutic targets for diseases ranging from neurodegenerative conditions to neoplastic disorders. However, effects of S1R activation and inhibition within glia cells are not well characterized. Within the eye, the astrocytes at the optic nerve head are crucial to the health and survival of the neurons that send visual information to the brain. In this study, we used the S1R-specific agonist, (+)-pentazocine, to evaluate S1R activation within optic nerve head-derived astrocytes (ONHAs). Treatment of ONHAs with (+)-pentazocine attenuated the level and duration of stress-induced ERK phosphorylation following oxidative stress exposure and promoted survival of ONHAs. These effects were specific to S1R activation because they were not observed in ONHAs that were depleted of S1R using siRNA-mediated knockdown. Collectively, our results suggest that S1R activation suppresses ERK1/2 phosphorylation and protects ONHAs from oxidative stress-induced death.
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Affiliation(s)
- Jing Zhao
- James and Jean Culver Vision Discovery Institute, Augusta, Georgia, United States of America
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Barbara A. Mysona
- James and Jean Culver Vision Discovery Institute, Augusta, Georgia, United States of America
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Jing Wang
- James and Jean Culver Vision Discovery Institute, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Graydon B. Gonsalvez
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Sylvia B. Smith
- James and Jean Culver Vision Discovery Institute, Augusta, Georgia, United States of America
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Kathryn E. Bollinger
- James and Jean Culver Vision Discovery Institute, Augusta, Georgia, United States of America
- Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
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Wang J, Saul A, Cui X, Roon P, Smith SB. Absence of Sigma 1 Receptor Accelerates Photoreceptor Cell Death in a Murine Model of Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2017; 58:4545-4558. [PMID: 28877319 PMCID: PMC5586962 DOI: 10.1167/iovs.17-21947] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/31/2017] [Indexed: 02/06/2023] Open
Abstract
Purpose Sigma 1 Receptor (Sig1R) is a novel therapeutic target in neurodegenerative diseases, including retinal disease. Sig1R-/- mice have late-onset retinal degeneration with ganglion cell loss that worsens under stress. Whether Sig1R plays a role in maintaining other retinal neurons is unknown, but was investigated here using rd10 mice, a model of severe photoreceptor degeneration. Methods Wild-type, rd10, and rd10/Sig1R-/- mice were subjected to ERG and spectral-domain optical coherence tomography (SD-OCT) to assess visual function/structure in situ. Retinas imaged microscopically were subjected to morphometric analysis, immunodetection of cones, and analysis of gliosis. Oxidative and endoplasmic reticulum (ER) stress was evaluated at mRNA/protein levels. Results Photopic ERG responses were reduced significantly in rd10/Sig1R-/- versus rd10 mice at P28 (31 ± 6 vs. 56 ± 7 μV), indicating accelerated cone loss when Sig1R was absent. At P28, SD-OCT revealed reduced retinal thickness in rd10/Sig1R-/- mice (60% of WT) versus rd10 (80% of WT). Morphometric analysis disclosed profound photoreceptor nuclei loss in rd10/Sig1R-/- versus rd10 mice. rd10/Sig1R-/- mice had 35% and 60% fewer photoreceptors, respectively, at P28 and P35, than rd10. Peanut agglutinin cone labeling decreased significantly; gliosis increased significantly in rd10/Sig1R-/- versus rd10 mice. At P21, NRF2 levels increased in rd10/Sig1R-/- mice versus rd10 and downstream antioxidants increased indicating oxidative stress. At P28, ER stress genes/proteins, especially XBP1, a potent transcriptional activator of the unfolded protein response and CHOP, a proapoptotic transcription factor, increased significantly in rd10/Sig1R-/- mice versus rd10. Conclusions Photoreceptor cell degeneration accelerates and cone function diminishes much earlier in rd10/Sig1R-/- than rd10 mice emphasizing the importance of Sig1R as a modulator of retinal cell survival.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, The Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Alan Saul
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
- Department of Ophthalmology, Augusta University, Augusta, Georgia, United States
| | - Xuezhi Cui
- Department of Cellular Biology and Anatomy, The Medical College of Georgia at 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, The Medical College of Georgia at Augusta University, Augusta, Georgia, United States
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, The Medical College of Georgia at Augusta University, Augusta, Georgia, United States
- The James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
- Department of Ophthalmology, Augusta University, Augusta, Georgia, United States
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Mavlyutov TA, Yang H, Epstein ML, Ruoho AE, Yang J, Guo LW. APEX2-enhanced electron microscopy distinguishes sigma-1 receptor localization in the nucleoplasmic reticulum. Oncotarget 2017; 8:51317-51330. [PMID: 28881650 PMCID: PMC5584251 DOI: 10.18632/oncotarget.17906] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/04/2017] [Indexed: 12/03/2022] Open
Abstract
The sigma-1 receptor (Sig1R) is an endoplasmic reticulum chaperonin that is attracting tremendous interest as a potential anti-neurodegenerative target. While this membrane protein is known to reside in the inner nuclear envelope (NE) and influences transcription, apparent Sig1R presence in the nucleoplasm is often observed, seemingly contradicting its NE localization. We addressed this confounding issue by applying an antibody-free approach of electron microscopy (EM) to define Sig1R nuclear localization. We expressed APEX2 peroxidase fused to Sig1R-GFP in a Sig1R-null NSC34 neuronal cell line generated with CRISPR-Cas9. APEX2-catalyzed gold/silver precipitation markedly improved EM clarity and confirmed an apparent intra-nuclear presence of Sig1R. However, serial sectioning combined with APEX2-enhanced EM revealed that Sig1R actually resided in the nucleoplasmic reticulum (NR), a specialized nuclear compartment formed via NE invagination into the nucleoplasm. NR cross-sections also indicated Sig1R in ring-shaped NR membranes. Thus, this study distinguishes Sig1R in the NR which could otherwise appear localized in the nucleoplasm if detected with low-resolution methods. Our finding is important for uncovering potential Sig1R regulations in the nucleus.
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Affiliation(s)
- Timur A Mavlyutov
- Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin, Madison, WI 53705, USA
| | - Huan Yang
- Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin, Madison, WI 53705, USA
| | - Miles L Epstein
- Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA
| | - Arnold E Ruoho
- Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA
| | - Jay Yang
- Department of Anesthesiology, Wisconsin Institute for Medical Research, University of Wisconsin, Madison, WI 53705, USA
| | - Lian-Wang Guo
- Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin, Madison, WI 53705, USA.,McPherson Eye Research Institute, University of Wisconsin, Madison, WI 53705, USA.,Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.,Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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24
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Dalwadi DA, Kim S, Schetz JA. Activation of the sigma-1 receptor by haloperidol metabolites facilitates brain-derived neurotrophic factor secretion from human astroglia. Neurochem Int 2017; 105:21-31. [PMID: 28188803 PMCID: PMC5375023 DOI: 10.1016/j.neuint.2017.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/31/2017] [Accepted: 02/06/2017] [Indexed: 02/07/2023]
Abstract
Glial cells play a critical role in neuronal support which includes the production and release of the neurotrophin brain-derived neurotrophic factor (BDNF). Activation of the sigma-1 receptor (S1R) has been shown to attenuate inflammatory stress-mediated brain injuries, and there is emerging evidence that this may involve a BDNF-dependent mechanism. In this report we studied S1R-mediated BDNF release from human astrocytic glial cells. Astrocytes express the S1R, which mediates BDNF release when stimulated with the prototypical S1R agonists 4-PPBP and (+)-SKF10047. This effect could be antagonized by a selective concentration of the S1R antagonist BD1063. Haloperidol is known to have high affinity interactions with the S1R, yet it was unable to facilitate BDNF release. Remarkably, however, two metabolites of haloperidol, haloperidol I and haloperidol II (reduced haloperidol), were discovered to facilitate BDNF secretion and this effect was antagonized by BD1063. Neither 4-PPBP, nor either of the haloperidol metabolites affected the level of BDNF mRNA as assessed by qPCR. These results demonstrate for the first time that haloperidol metabolites I and II facilitate the secretion of BDNF from astrocytes by acting as functionally selective S1R agonists.
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Affiliation(s)
- Dhwanil A Dalwadi
- Department of Pharmacology & Neuroscience, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas, 76107, United States
| | - Seongcheol Kim
- Department of Pharmacology & Neuroscience, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas, 76107, United States
| | - John A Schetz
- Department of Pharmacology & Neuroscience, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, Texas, 76107, United States; Institute for Healthy Aging, Center for Neuroscience Discovery, United States.
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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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Wang J, Saul A, Roon P, Smith SB. Activation of the molecular chaperone, sigma 1 receptor, preserves cone function in a murine model of inherited retinal degeneration. Proc Natl Acad Sci U S A 2016; 113:E3764-72. [PMID: 27298364 PMCID: PMC4932934 DOI: 10.1073/pnas.1521749113] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Retinal degenerative diseases are major causes of untreatable blindness, and novel approaches to treatment are being sought actively. Here we explored the activation of a unique protein, sigma 1 receptor (Sig1R), in the treatment of PRC loss because of its multifaceted role in cellular survival. We used Pde6β(rd10) (rd10) mice, which harbor a mutation in the rod-specific phosphodiesterase gene Pde6β and lose rod and cone photoreceptor cells (PRC) within the first 6 wk of life, as a model for severe retinal degeneration. Systemic administration of the high-affinity Sig1R ligand (+)-pentazocine [(+)-PTZ] to rd10 mice over several weeks led to the rescue of cone function as indicated by electroretinographic recordings using natural noise stimuli and preservation of cone cells upon spectral domain optical coherence tomography and retinal histological examination. The protective effect appears to result from the activation of Sig1R, because rd10/Sig1R(-/-) mice administered (+)-PTZ exhibited no cone preservation. (+)-PTZ treatment was associated with several beneficial cellular phenomena including attenuated reactive gliosis, reduced microglial activation, and decreased oxidative stress in mutant retinas. To our knowledge, this is the first report that activation of Sig1R attenuates inherited PRC loss. The findings may have far-reaching therapeutic implications for retinal neurodegenerative diseases.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology/Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912
| | - Alan Saul
- James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912; Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Penny Roon
- Department of Cellular Biology/Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912
| | - Sylvia B Smith
- Department of Cellular Biology/Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912; James and Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA 30912; Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA 30912
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28
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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: 13] [Impact Index Per Article: 1.6] [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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Wang J, Shanmugam A, Markand S, Zorrilla E, Ganapathy V, Smith SB. Sigma 1 receptor regulates the oxidative stress response in primary retinal Müller glial cells via NRF2 signaling and system xc(-), the Na(+)-independent glutamate-cystine exchanger. Free Radic Biol Med 2015; 86:25-36. [PMID: 25920363 PMCID: PMC4554890 DOI: 10.1016/j.freeradbiomed.2015.04.009] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 04/02/2015] [Accepted: 04/07/2015] [Indexed: 01/18/2023]
Abstract
Oxidative stress figures prominently in retinal diseases, including diabetic retinopathy, and glaucoma. Ligands for σ1R, a unique transmembrane protein localized to the endoplasmic reticulum, mitochondria, and nuclear and plasma membranes, have profound retinal neuroprotective properties in vitro and in vivo. Studies to determine the mechanism of σ1R-mediated retinal neuroprotection have focused mainly on neurons. Little is known about the effects of σ1R on Müller cell function, yet these radial glial cells are essential for homeostatic support of the retina. Here we investigated whether σ1R mediates the oxidative stress response of Müller cells using wild-type (WT) and σ1R-knockout (σ1RKO) mice. We observed increased endogenous reactive oxygen species (ROS) levels in σ1RKO Müller cells compared to WT, which was accompanied by decreased expression of Sod1, catalase, Nqo1, Hmox1, Gstm6, and Gpx1. The protein levels of SOD1, CAT, NQO1, and GPX1 were also significantly decreased. The genes encoding these antioxidants contain an antioxidant response element (ARE), which under stress is activated by NRF2, a transcription factor that typically resides in the cytoplasm bound by KEAP1. In the σ1RKO Müller cells Nrf2 expression was decreased significantly at the gene (and protein) level, whereas Keap1 gene (and protein) levels were markedly increased. NRF2-ARE binding affinity was decreased markedly in σ1RKO Müller cells. We investigated system xc(-), the cystine-glutamate exchanger important for synthesis of glutathione (GSH), and observed decreased function in σ1RKO Müller cells compared to WT as well as decreased GSH and GSH/GSSG ratios. This was accompanied by decreased gene and protein levels of xCT, the unique component of system xc(-). We conclude that Müller glial cells lacking σ1R manifest elevated ROS, perturbation of antioxidant balance, suppression of NRF2 signaling, and impaired function of system xc(-). The data suggest that the oxidative stress-mediating function of retinal Müller glial cells may be compromised in the absence of σ1R. The neuroprotective role of σ1R may be linked directly to the oxidative stress-mediating properties of supportive glial cells.
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Affiliation(s)
- Jing Wang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912-2000, USA; James and Jean Culver Vision Discovery Institute, Augusta, GA 30912-2000, USA
| | - Arul Shanmugam
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912-2000, USA; James and Jean Culver Vision Discovery Institute, Augusta, GA 30912-2000, USA
| | - Shanu Markand
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912-2000, USA; James and Jean Culver Vision Discovery Institute, Augusta, GA 30912-2000, USA
| | - Eric Zorrilla
- Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Vadivel Ganapathy
- James and Jean Culver Vision Discovery Institute, Augusta, GA 30912-2000, USA; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912-2000, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912-2000, USA; James and Jean Culver Vision Discovery Institute, Augusta, GA 30912-2000, USA; Department of Ophthalmology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912-2000, USA.
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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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Jin JL, Fang M, Zhao YX, Liu XY. Roles of sigma-1 receptors in Alzheimer's disease. Int J Clin Exp Med 2015; 8:4808-4820. [PMID: 26131055 PMCID: PMC4484039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 04/03/2015] [Indexed: 06/04/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the leading cause of senile dementia all over the world. Still no existing drugs can effectively reverse the cognitive impairment. However, Sigma-1 (σ-1) receptors have been long implicated in multiple neurological and psychiatric conditions over these years. In this review, we discuss the current understanding of σ-1 receptor functions. Through regulation of lipid rafts, secretases, kinases, neuroceptors and ion channels, σ-1 receptors can influence cellular signal transduction, TCA cycle, oxidative stress, neuron plasticity and neurotransmitter release etc. Based on this, we suggest the key cellular mechanisms linking σ-1 receptor to Alzheimer's disease. Besides, we detail the evidences showing that σ-1 receptors agonists, being the promising compounds for treatment of cognitive dysfunction, exhibit robust neuroprotection and anti-amnesia effect against Aβ neurotoxicity in the progress of Alzheimer's disease. The evidence comes from animal models, preclinical studies in humans and full clinical trials. In addition, the questions to be solved regarding this receptor are also presented. When concerned with NMDAR, σ-1 receptor activation may result in two totally different influences on AD. Utilization of σ-1 agents early in AD remains an overlooked therapeutic opportunity. This article may pave the way for further studies about sigma-1 receptor on Alzheimer's disease.
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Affiliation(s)
- Jia-Li Jin
- Department of Neurology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine China
| | - Min Fang
- Department of Neurology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine China
| | - Yan-Xin Zhao
- Department of Neurology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine China
| | - Xue-Yuan Liu
- Department of Neurology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine China
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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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Primary retinal cultures as a tool for modeling diabetic retinopathy: an overview. BIOMED RESEARCH INTERNATIONAL 2015; 2015:364924. [PMID: 25688355 PMCID: PMC4320900 DOI: 10.1155/2015/364924] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/04/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
Experimental models of diabetic retinopathy (DR) have had a crucial role in the comprehension of the pathophysiology of the disease and the identification of new therapeutic strategies. Most of these studies have been conducted in vivo, in animal models. However, a significant contribution has also been provided by studies on retinal cultures, especially regarding the effects of the potentially toxic components of the diabetic milieu on retinal cell homeostasis, the characterization of the mechanisms on the basis of retinal damage, and the identification of potentially protective molecules. In this review, we highlight the contribution given by primary retinal cultures to the study of DR, focusing on early neuroglial impairment. We also speculate on possible themes into which studies based on retinal cell cultures could provide deeper insight.
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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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Ha Y, Saul A, Tawfik A, Zorrilla EP, Ganapathy V, Smith SB. Diabetes accelerates retinal ganglion cell dysfunction in mice lacking sigma receptor 1. Mol Vis 2012; 18:2860-70. [PMID: 23233788 PMCID: PMC3519370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 11/28/2012] [Indexed: 12/02/2022] Open
Abstract
PURPOSE Sigma receptor 1 (σR1) is a non-opioid transmembrane protein that may act as a molecular chaperone at the endoplasmic reticulum-mitochondrial membrane. Ligands for σR1, such as (+)-pentazocine [(+)-PTZ], confer marked retinal neuroprotection in vivo and in vitro. Recently we analyzed the retinal phenotype of mice lacking σR1 (σR1 KO) and observed normal retinal morphology and function in young mice (5-30 weeks) but diminished negative scotopic threshold responses (nSTRs), retinal ganglion cell (RGC) loss, and disruption of optic nerve axons consistent with inner retinal dysfunction by 1 year. These data led us to test the hypothesis that σR1 may be critical in forestalling chronic retinal stress; diabetes was used as the model of chronic stress. METHODS To determine whether σR1 is required for (+)-PTZ neuroprotective effects, primary RGCs isolated from wild-type (WT) and σR1 KO mice were exposed to xanthine-xanthine oxidase (10 µM:2 mU/ml) to induce oxidative stress in the presence or absence of (+)-PTZ. Cell death was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis. To assess effects of chronic stress on RGC function, diabetes was induced in 3-week C57BL/6 (WT) and σR1 KO mice, using streptozotocin to yield four groups: WT nondiabetic (WT non-DB), WT diabetic (WT-DB), σR1 KO non-DB, and σR1 KO-DB. After 12 weeks of diabetes, when mice were 15-weeks old, intraocular pressure (IOP) was recorded, electrophysiologic testing was performed (including detection of nSTRs), and the number of RGCs was counted in retinal histological sections. RESULTS In vitro studies showed that (+)-PTZ could not prevent oxidative stress-induced death of RGCs harvested from σR1 KO mice but afforded robust protection against death of RGCs harvested from WT mice. In the studies of chronic stress induced by diabetes, the IOP measured in the four mouse groups was within the normal range; however, there was a significant increase in the IOP of σR1 KO-DB mice (16 ± 0.5 mmHg) compared to the other groups tested (σR1 KO non-DB, WT non-DB, WT-DB: ~12 ± 0.6 mmHg). Regarding electrophysiologic testing, the nSTRs of σR1 KO non-DB mice were similar to WT non-DB mice at 15 weeks; however, they were significantly lower in σR1 KO-DB mice (5 ± 1 µV) compared to the other groups, including, notably, σR1 KO-nonDB (12±2 µV). As expected, the number of RGCs in σR1 KO non-DB mice was similar to WT non-DB mice at 15 weeks, but under chronic stress of diabetes there were fewer RGCs in retinas of σR1 KO-DB mice. CONCLUSIONS This is the first report showing unequivocally that the neuroprotective effects of (+)-PTZ require σR1. σR1 KO mice show normal retinal structure and function at young ages; however, when subjected to the chronic stress of diabetes, there is an acceleration of retinal functional deficits in σR1 KO mice such that ganglion cell dysfunction is observed at a much earlier age than nondiabetic σR1 KO mice. The data support the hypothesis that σR1 plays a key role in modulating retinal stress and may be an important target for retinal disease.
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Affiliation(s)
- Yonju Ha
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
| | - Alan Saul
- Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Department of Ophthalmology, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
| | - Amany Tawfik
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
| | | | - Vadivel Ganapathy
- Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Vision Discovery Institute, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
- Department of Ophthalmology, Medical College of Georgia, Georgia Health Sciences University, Augusta, GA
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Wang L, Eldred JA, Sidaway P, Sanderson J, Smith AJO, Bowater RP, Reddan JR, Wormstone IM. Sigma 1 receptor stimulation protects against oxidative damage through suppression of the ER stress responses in the human lens. Mech Ageing Dev 2012; 133:665-74. [PMID: 23041531 DOI: 10.1016/j.mad.2012.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 08/31/2012] [Accepted: 09/24/2012] [Indexed: 11/23/2022]
Abstract
Stimulation of sigma-1 receptors is reported to protect against oxidative stress. The present study uses cells and tissue from the human lens to elucidate the relationship between the sigma 1 receptor, ER stress and oxidative stress-induced damage. Exposure of the human lens cell line FHL124 to increasing concentrations of H(2)O(2) led to reduced cell viability and increased apoptosis. In response to 30 μM H(2)O(2), levels of the ER stress proteins BiP, ATF6 and pEIF2α were significantly increased within 4h of exposure. Expression of the sigma 1 receptor was markedly increased in response to H(2)O(2). Application of 10 and 30 μM (+)-pentazocine, a sigma 1 receptor agonist, significantly inhibited the H(2)O(2) induced cell death. (+)-Pentazocine also suppressed the oxidative stress induced reduction of pro-caspase 12 and suppressed the induction of the ER stress proteins BiP and EIF2α. When applied to cultured human lenses, (+)-pentazocine protected against apoptotic cell death, LDH release and against H(2)O(2) induced opacification. These data demonstrate that stimulation of the sigma 1 receptor provides significant protection from oxidative damage and is, therefore, a putative therapeutic approach to delay the onset of diseases that may be triggered by oxidative damage, including cataract formation.
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Affiliation(s)
- Lixin Wang
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
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Behensky AA, Cortes-Salva M, Seminerio MJ, Matsumoto RR, Antilla JC, Cuevas J. In vitro evaluation of guanidine analogs as sigma receptor ligands for potential anti-stroke therapeutics. J Pharmacol Exp Ther 2012; 344:155-66. [PMID: 23065135 DOI: 10.1124/jpet.112.199513] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Currently, the only Food and Drug Administration-approved treatment of acute stroke is recombinant tissue plasminogen activator, which must be administered within 6 hours after stroke onset. The pan-selective σ-receptor agonist N,N'-di-o-tolyl-guanidine (o-DTG) has been shown to reduce infarct volume in rats after middle cerebral artery occlusion, even when administered 24 hours after stroke. DTG derivatives were synthesized to develop novel compounds with greater potency than o-DTG. Fluorometric Ca(2+) imaging was used in cultured cortical neurons to screen compounds for their capacity to reduce ischemia- and acidosis-evoked cytosolic Ca(2+) overload, which has been linked to stroke-induced neurodegeneration. In both assays, migration of the methyl moiety produced no significant differences, but removal of the group increased potency of the compound for inhibiting acidosis-induced [Ca(2+)](i) elevations. Chloro and bromo substitution of the methyl moiety in the meta and para positions increased potency by ≤160%, but fluoro substitutions had no effect. The most potent DTG derivative tested was N,N'-di-p-bromo-phenyl-guanidine (p-BrDPhG), which had an IC(50) of 2.2 µM in the ischemia assay, compared with 74.7 μM for o-DTG. Microglial migration assays also showed that p-BrDPhG is more potent than o-DTG in this marker for microglial activation, which is also linked to neuronal injury after stroke. Radioligand binding studies showed that p-BrDPhG is a pan-selective σ ligand. Experiments using the σ-1 receptor-selective antagonist 1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine dihydrochloride (BD-1063) demonstrated that p-BrDPhG blocks Ca(2+) overload via σ-1 receptor activation. The study identified four compounds that may be more effective than o-DTG for the treatment of ischemic stroke at delayed time points.
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Affiliation(s)
- Adam A Behensky
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, 12901 Bruce B. Downs Blvd., MDC-9, Tampa, FL 33612-4799, USA
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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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Pal A, Fontanilla D, Gopalakrishnan A, Chae YK, Markley JL, Ruoho AE. The sigma-1 receptor protects against cellular oxidative stress and activates antioxidant response elements. Eur J Pharmacol 2012; 682:12-20. [PMID: 22381068 PMCID: PMC3314091 DOI: 10.1016/j.ejphar.2012.01.030] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 01/19/2012] [Accepted: 01/24/2012] [Indexed: 10/28/2022]
Abstract
Sigma-1 receptors are associated with Alzheimer's disease, major depressive disorders, and schizophrenia. These receptors show progrowth/antiapoptotic properties via their chaperoning functions to counteract ER (endoplasmic reticulum) stress, to block neurodegeneration, and to regulate neuritogenesis. The sigma-1 receptor knock out mouse offered an opportunity to assess possible mechanisms by which the sigma-1 receptor modulates cellular oxidative stress. Nuclear magnetic resonance (NMR) metabolomic screening of the WT (wild type) and sigma-1 KO (knockout) livers was performed to investigate major changes in metabolites that are linked to oxidative stress. Significant changes in protein levels were also identified by two-dimensional (2D) gel electrophoresis and mass spectrometry. Increased levels of the antioxidant protein peroxiredoxin 6 (Prdx6), and the ER chaperone BiP (GRP78) compared to WT littermates were detected. Oxidative stress was measured in WT and sigma-1 KO mouse liver homogenates, in primary hepatocytes and in lung homogenates. Furthermore, sigma-1 receptor mediated activation of the antioxidant response element (ARE) to upregulate NAD(P)H quinone oxidoreductase 1 (NQO1) and superoxide dismutase 1 (SOD1) mRNA expression in COS cells was shown by RT PCR. These novel functions of the sigma-1 receptor were sensitive to well-known sigma ligands via their antagonist/agonist properties.
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Affiliation(s)
- Arindam Pal
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Dominique Fontanilla
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Anupama Gopalakrishnan
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Young-Kee Chae
- Department of Chemistry, Sejong University, Seoul, South Korea
| | - John L Markley
- Department of Biochemistry and NMRFAM, University of Wisconsin-Madison, WI, USA
| | - Arnold E Ruoho
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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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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Chu UB, Hajipour AR, Ramachandran S, Ruoho AE. Characterization of interactions of 4-nitrophenylpropyl-N-alkylamine with ς receptors. Biochemistry 2011; 50:7568-78. [PMID: 21790129 PMCID: PMC3234165 DOI: 10.1021/bi2004872] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Sigma receptors are small membrane proteins implicated in a number of pathophysiological conditions, including drug addiction, psychosis, and cancer; thus, small molecule inhibitors of sigma receptors have been proposed as potential pharmacotherapeutics for these diseases. We previously discovered that endogenous monochain N-alkyl sphingolipids, including d-erythro-sphingosine, sphinganine, and N,N-dimethylsphingosine, bind to the sigma-1 receptor at physiologically relevant concentrations [Ramachandran, S., et al. (2009) Eur. J. Pharmacol. 609, 19-26]. Here, we investigated several N-alkylamines of varying chain lengths as sigma receptor ligands. Although the K(I) values for N-alkylamines were found to be in the micromolar range, when N-3-phenylpropyl and N-3-(4-nitrophenyl)propyl derivatives of butylamine (1a and 1b, respectively), heptylamine (2a and 2b, respectively), dodecylamine (3a and 3b, respectively), and octadecylamine (4a and 4b, respectively) were evaluated as sigma receptor ligands, we found that these compounds exhibited nanomolar affinities with both sigma-1 and sigma-2 receptors. A screen of high-affinity ligands 2a, 2b, 3a, and 3b against a variety of other receptors and/or transporters confirmed these four compounds to be highly selective mixed sigma-1 and sigma-2 ligands. Additionally, in HEK-293 cells reconstituted with K(v)1.4 potassium channel and the sigma-1 receptor, these derivatives were able to inhibit the outward current from the channel, consistent with sigma receptor modulation. Finally, cytotoxicity assays showed that 2a, 2b, 3a, and 3b were highly potent against a number of cancer cell lines, demonstrating their potential utility as mixed sigma-1 and sigma-2 receptor anticancer agents.
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Affiliation(s)
- Uyen B. Chu
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, Wisconsin 53706
| | - Abdol R. Hajipour
- Pharmaceutical Research Laboratory, College of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran
| | - Subramaniam Ramachandran
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, Wisconsin 53706
| | - Arnold E. Ruoho
- Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, Wisconsin 53706
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van Waarde A, Ramakrishnan NK, Rybczynska AA, Elsinga PH, Ishiwata K, Nijholt IM, Luiten PGM, Dierckx RA. The cholinergic system, sigma-1 receptors and cognition. Behav Brain Res 2011; 221:543-54. [PMID: 20060423 DOI: 10.1016/j.bbr.2009.12.043] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 12/26/2009] [Indexed: 12/31/2022]
Abstract
This article provides an overview of present knowledge regarding the relationship between the cholinergic system and sigma-1 receptors, and discusses potential applications of sigma-1 receptor agonists in the treatment of memory deficits and cognitive disorders. Sigma-1 receptors, initially considered as a subtype of the opioid family, are unique ligand-regulated molecular chaperones in the endoplasmatic reticulum playing a modulatory role in intracellular calcium signaling and in the activity of several neurotransmitter systems, particularly the cholinergic and glutamatergic pathways. Several central nervous system (CNS) drugs show high to moderate affinities for sigma-1 receptors, including acetylcholinesterase inhibitors (donepezil), antipsychotics (haloperidol, rimcazole), selective serotonin reuptake inhibitors (fluvoxamine, sertraline) and monoamine oxidase inhibitors (clorgyline). These compounds can influence cognitive functions both via their primary targets and by activating sigma-1 receptors in the CNS. Sigma-1 agonists show powerful anti-amnesic and neuroprotective effects in a large variety of animal models of cognitive dysfunction involving, among others (i) pharmacologic target blockade (with muscarinic or NMDA receptor antagonists or p-chloroamphetamine); (ii) selective lesioning of cholinergic neurons; (iii) CNS administration of β-amyloid peptides; (iv) aging-induced memory loss, both in normal and senescent-accelerated rodents; (v) neurodegeneration induced by toxic compounds (CO, trimethyltin, cocaine), and (vi) prenatal restraint stress.
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Affiliation(s)
- Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
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Mavlyutov TA, Nickells RW, Guo LW. Accelerated retinal ganglion cell death in mice deficient in the Sigma-1 receptor. Mol Vis 2011; 17:1034-43. [PMID: 21541278 PMCID: PMC3084245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/21/2011] [Indexed: 11/03/2022] Open
Abstract
PURPOSE The sigma-1 receptor (σR1), a ligand-operated chaperone, has been inferred to be neuroprotective in previous studies using σR1 ligands. The σR1 specificity of the protective function, however, has yet to be firmly established, due to the existence of non-σR1 targets of the ligands. Here, we used the σR1-knockout mouse (Sigmar1(-/-)) to demonstrate unambiguously the role of the σR1 in protecting the retinal ganglion cells against degeneration after acute damage to the optic nerve. METHODS Retinal σR binding sites were labeled with radioiodinated σR ligands and analyzed by autoradiography. Localization of the σR1 was performed by indirect immunofluorescence on frozen retinal sections. Retinal ganglion cell death was induced by acute optic nerve crush in wild-type and Sigmar1(-/-) mice. Surviving cells in the ganglion cell layer were counted on Nissl-stained retinal whole mounts 7 days after the crush surgery. RESULTS Photoaffinity labeling indicated the presence of the σR1 in the retina, in concentrations equivalent to those in liver tissue. Immunolabeling detected this receptor in cells of both the ganglion cell layer and the photoreceptor cell layer in wild-type retinas. Quantification of cells remaining after optic nerve crush showed that 86.8±7.9% cells remained in the wild-type ganglion cell layer, but only 68.3±3.4% survived in the Sigmar1(-/-), demonstrating a significant difference between the wild-type and the Sigmar1(-/-) in crush-induced ganglion cell loss. CONCLUSIONS Our data indicated faster retinal ganglion cell death in Sigmar1(-/-) than in wild-type mice under the stresses caused by optic nerve crush, providing direct evidence for a role of the σR1 in alleviating retinal degeneration. This conclusion is consistent with the previous pharmacological studies using σR1 agonists. Thus, our study supports the idea that the σR1 is a promising therapeutic target for neurodegenerative retinal diseases, such as glaucoma.
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Affiliation(s)
- Timur A. Mavlyutov
- Department of Pharmacology, University of Wisconsin, School of Medicine and Public Health, Madison, WI
| | - Robert W. Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, School of Medicine and Public Health, Madison, WI
| | - Lian-Wang Guo
- Department of Pharmacology, University of Wisconsin, School of Medicine and Public Health, Madison, WI
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Bhuiyan MS, Fukunaga K. Targeting sigma-1 receptor signaling by endogenous ligands for cardioprotection. Expert Opin Ther Targets 2011; 15:145-55. [PMID: 21204730 DOI: 10.1517/14728222.2011.546350] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
INTRODUCTION The sigma receptors, initially described as a subtype of opioid receptors, are now considered to be a unique receptor expressed in neonatal rat cardiomyocytes and in the plasma membrane of adult rat cardiomyocytes. A number of sigma receptor ligands influence cardiovascular function and the heart has binding sites for sigma receptor ligands that alter contractility both in vivo and in vitro. The human sigma-1 receptor gene contains a steroid-binding component and gonadal steroid dehydroepiandrosterone (DHEA) which interacts with the sigma-1 receptor. AREAS COVERED We recently documented that the pathophysiological role of the sigma-1 receptor in the heart and its modulation using DHEA, was cardioprotective. Moreover, agonist-induced activation of the sigma-1 receptor modulates diverse ion channels and thereby regulates heart function. Novel concepts for understanding the pathophysiological relevance of sigma-1 receptors in the progression of heart failure, and developing clinical therapeutics targeting for the receptor in cardiovascular diseases are discussed. EXPERT OPINION Future studies should attempt to develop cardiac-specific knockdown of the sigma-1 receptor to observe its downstream signaling. We expect that these observations will lead to a novel therapeutic target for which a new class of antihypertrophic drugs can be designed.
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Affiliation(s)
- Md Shenuarin Bhuiyan
- Tohoku University, Graduate School of Pharmaceutical Sciences, Department of Pharmacology, Aramaki-Aoba Aoba-ku, Sendai 980-8578, Japan.
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Ha Y, Dun Y, Thangaraju M, Duplantier J, Dong Z, Liu K, Ganapathy V, Smith SB. Sigma receptor 1 modulates endoplasmic reticulum stress in retinal neurons. Invest Ophthalmol Vis Sci 2011; 52:527-40. [PMID: 20811050 PMCID: PMC3053296 DOI: 10.1167/iovs.10-5731] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 06/15/2010] [Accepted: 08/17/2010] [Indexed: 01/30/2023] Open
Abstract
PURPOSE To investigate the mechanism of σ receptor 1 (σR1) neuroprotection in retinal neurons. METHODS Oxidative stress, which is implicated in diabetic retinopathy, was induced in mouse primary ganglion cells (GCs) and RGC-5 cells, and the effect of the σR1 ligand (+)-pentazocine on pro- and anti-apoptotic and endoplasmic reticulum (ER) stress gene expression was examined. Binding of σR1 to BiP, an ER chaperone protein, and σR1 phosphorylation status were examined by immunoprecipitation. Retinas were harvested from Ins2Akita/+ diabetic mice treated with (+)-pentazocine, and the expression of ER stress genes and of the retinal transcriptome was evaluated. RESULTS Oxidative stress induced the death of primary GCs and RGC-5 cells. The effect was decreased by the application of (+)-pentazocine. Stress increased σR1 binding to BiP and enhanced σR1 phosphorylation in RGC-5 cells. BiP binding was prevented, and σR1 phosphorylation decreased in the presence of (+)-pentazocine. The ER stress proteins PERK, ATF4, ATF6, IRE1α, and CHOP were upregulated in RGC-5 cells during oxidative stress, but decreased in the presence of (+)-pentazocine. A similar phenomenon was observed in retinas of Ins2Akita/+ diabetic mice. Retinal transcriptome analysis of Ins2Akita/+ mice compared with wild-type revealed differential expression of the genes critically involved in oxidative stress, differentiation, and cell death. The expression profile of those genes was reversed when the Ins2Akita/+ mice were treated with (+)-pentazocine. CONCLUSIONS In retinal neurons, the molecular chaperone σR1 binds BiP under stressful conditions; (+)-pentazocine may exert its effects by dissociating σR1 from BiP. As stress in retinal cells increases, phosphorylation of σR1 is increased, which is attenuated when agonists bind to the receptor.
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Affiliation(s)
- Yonju Ha
- From the Departments of Cellular Biology and Anatomy
| | - Ying Dun
- From the Departments of Cellular Biology and Anatomy
| | | | | | - Zheng Dong
- From the Departments of Cellular Biology and Anatomy
| | - Kebin Liu
- Biochemistry and Molecular Biology, and
| | | | - Sylvia B. Smith
- From the Departments of Cellular Biology and Anatomy
- Ophthalmology, Medical College of Georgia, Augusta, Georgia
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Cobos EJ, Entrena JM, Nieto FR, Cendán CM, Del Pozo E. Pharmacology and therapeutic potential of sigma(1) receptor ligands. Curr Neuropharmacol 2010; 6:344-66. [PMID: 19587856 PMCID: PMC2701284 DOI: 10.2174/157015908787386113] [Citation(s) in RCA: 287] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 07/18/2008] [Accepted: 07/09/2008] [Indexed: 11/22/2022] Open
Abstract
Sigma (σ) receptors, initially described as a subtype of opioid receptors, are now considered unique receptors. Pharmacological studies have distinguished two types of σ receptors, termed σ1 and σ2. Of these two subtypes, the σ1 receptor has been cloned in humans and rodents, and its amino acid sequence shows no homology with other mammalian proteins. Several psychoactive drugs show high to moderate affinity for σ1 receptors, including the antipsychotic haloperidol, the antidepressant drugs fluvoxamine and sertraline, and the psychostimulants cocaine and methamphetamine; in addition, the anticonvulsant drug phenytoin allosterically modulates σ1 receptors. Certain neurosteroids are known to interact with σ1 receptors, and have been proposed to be their endogenous ligands. These receptors are located in the plasma membrane and in subcellular membranes, particularly in the endoplasmic reticulum, where they play a modulatory role in intracellular Ca2+ signaling. Sigma1 receptors also play a modulatory role in the activity of some ion channels and in several neurotransmitter systems, mainly in glutamatergic neurotransmission. In accordance with their widespread modulatory role, σ1 receptor ligands have been proposed to be useful in several therapeutic fields such as amnesic and cognitive deficits, depression and anxiety, schizophrenia, analgesia, and against some effects of drugs of abuse (such as cocaine and methamphetamine). In this review we provide an overview of the present knowledge of σ1 receptors, focussing on σ1 ligand neuropharmacology and the role of σ1 receptors in behavioral animal studies, which have contributed greatly to the potential therapeutic applications of σ1 ligands.
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Affiliation(s)
- E J Cobos
- Department of Pharmacology and Institute of Neuroscience, Faculty of Medicine, University of Granada, Granada, Spain
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