1
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An investigation of Sigma-1 receptor expression and ligand-induced endoplasmic reticulum stress in breast cancer. Cancer Gene Ther 2023; 30:368-374. [PMID: 36352093 DOI: 10.1038/s41417-022-00552-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/19/2022] [Accepted: 10/17/2022] [Indexed: 11/11/2022]
Abstract
Targeted therapeutic options and prognostic biomarkers for hormone receptor- or Her2 receptor-negative breast cancers are severely limited. The sigma-1 receptor, a stress-activated chaperone, is frequently dysregulated in disease. However, its significance in breast cancer (BCa) has not been adequately explored. Here, we report that the sigma-1 receptor gene (SIGMAR1) is elevated in BCa, particularly in the aggressive triple-negative (TNBC) subtype. By examining several patient datasets, we found that high expression at both the gene (SIGMAR1) and protein (Sig1R) levels associated with poor survival outcomes, specifically in ER-Her2- groups. Our data further show that high SIGMAR1 was predictive of shorter survival times in patients treated with adjuvant chemotherapy (ChT). Interestingly, in a separate cohort who received neoadjuvant taxane + anthracycline treatment, elevated SIGMAR1 associated with higher rates of pathologic complete response (pCR). Treatment with a Sig1R antagonist, 1-(4-iodophenyl)-3-(2-adamantyl)guanidine (IPAG), activated the unfolded protein response (UPR) in TNBC (high-Sig1R expressing) and ER + (low-Sig1R expressing) BCa cell lines. In tamoxifen-resistant LY2 cells, IPAG caused Sig1R to aggregate and co-localise with the stress marker BiP. These findings showcase the potential of Sig1R as a novel biomarker in TNBC as well as highlight its ligand-induced interference with the stress-coping mechanisms of BCa cells.
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2
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Zhemkov V, Geva M, Hayden MR, Bezprozvanny I. Sigma-1 Receptor (S1R) Interaction with Cholesterol: Mechanisms of S1R Activation and Its Role in Neurodegenerative Diseases. Int J Mol Sci 2021; 22:4082. [PMID: 33920913 PMCID: PMC8071319 DOI: 10.3390/ijms22084082] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 12/11/2022] Open
Abstract
The sigma-1 receptor (S1R) is a 223 amino acid-long transmembrane endoplasmic reticulum (ER) protein. The S1R modulates the activity of multiple effector proteins, but its signaling functions are poorly understood. S1R is associated with cholesterol, and in our recent studies we demonstrated that S1R association with cholesterol induces the formation of S1R clusters. We propose that these S1R-cholesterol interactions enable the formation of cholesterol-enriched microdomains in the ER membrane. We hypothesize that a number of secreted and signaling proteins are recruited and retained in these microdomains. This hypothesis is consistent with the results of an unbiased screen for S1R-interacting partners, which we performed using the engineered ascorbate peroxidase 2 (APEX2) technology. We further propose that S1R agonists enable the disassembly of these cholesterol-enriched microdomains and the release of accumulated proteins such as ion channels, signaling receptors, and trophic factors from the ER. This hypothesis may explain the pleotropic signaling functions of the S1R, consistent with previously observed effects of S1R agonists in various experimental systems.
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Affiliation(s)
- Vladimir Zhemkov
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Michal Geva
- Prilenia Therapeutics Development LTD, Herzliya 4673304, Israel; (M.G.); (M.R.H.)
| | - Michael R. Hayden
- Prilenia Therapeutics Development LTD, Herzliya 4673304, Israel; (M.G.); (M.R.H.)
- Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, BC V6H 3V5, Canada
| | - Ilya Bezprozvanny
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA;
- Laboratory of Molecular Neurodegeneration, Peter the Great St Petersburg State Polytechnic University, 195251 St. Petersburg, Russia
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3
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Hong WC. Distinct Regulation of σ 1 Receptor Multimerization by Its Agonists and Antagonists in Transfected Cells and Rat Liver Membranes. J Pharmacol Exp Ther 2020; 373:290-301. [PMID: 32060048 DOI: 10.1124/jpet.119.262790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/04/2020] [Indexed: 11/22/2022] Open
Abstract
Extensive studies have shown that the σ 1 receptor (σ 1R) interacts with and modulates the activity of multiple proteins with important biological functions. Recent crystal structures of σ 1R as a homotrimer differ from a dimer-tetramer model postulated earlier. It remains inconclusive whether ligand binding regulates σ 1R oligomerization. Here, novel nondenaturing gel methods and mutational analysis were used to examine σ 1R oligomerization. In transfected cells, σ 1R exhibited as multimers, dimers, and monomers. Overall, σ 1R agonists decreased, whereas σ 1R antagonists increased σ 1R multimers, suggesting that agonists and antagonists differentially affect the stability of σ 1R multimers. Endogenous σ 1R in rat liver membranes also showed similar regulation of oligomerization as in cells. Mutations at key residues lining the trimerization interface (Arg119, Asp195, Phe191, Trp136, and Gly91) abolished multimerization without disrupting dimerization. Intriguingly, truncation of the N terminus reduced σ 1R to apparent monomer. These results demonstrate that multiple domains play crucial roles in coordinating high-order quaternary organization of σ 1R. The E102Q σ 1R mutant implicated in juvenile amyotrophic lateral sclerosis formed dimers only, suggesting that dysregulation of σ 1R multimeric assembly may impair its function. Interestingly, oligomerization of σ 1R was pH-dependent and correlated with changes in [3H](+)-pentazocine binding affinity and Bmax Combined with mutational analysis, it is reasoned that σ 1R multimers possess high-affinity and high-capacity [3H](+)-pentazocine binding, whereas monomers likely lack binding. These results suggest that σ 1R may exist in interconvertible oligomeric states in a dynamic equilibrium. Further exploration of ligand-regulated σ 1R multimerization may provide novel approaches to modulate the function of σ 1R and its interacting proteins. SIGNIFICANCE STATEMENT: The σ 1 receptor (σ 1R) modulates the activities of various partner proteins. Recently, crystal structures of σ 1R were elucidated as homotrimers. This study used novel nondenaturing gel methods to examine σ1R oligomerization in transfected cells and rat liver membranes. Overall, agonist binding decreased, whereas antagonist binding increased σ 1R multimers, which comprised trimers and larger units. σ 1R multimers were shown to bind [3H](+)-pentazocine with high affinity and high capacity. Furthermore, mutational analysis revealed a crucial role of its N-terminal domain in σ 1R multimerization.
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Affiliation(s)
- Weimin Conrad Hong
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana
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4
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Alamri MA, Alamri MA. Pharmacophore and docking-based sequential virtual screening for the identification of novel Sigma 1 receptor ligands. Bioinformation 2019; 15:586-595. [PMID: 31719769 PMCID: PMC6822515 DOI: 10.6026/97320630015586] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 08/31/2019] [Indexed: 11/23/2022] Open
Abstract
Sigma 1 receptor (σ1), a small transmembrane protein expressed in most human cells participates in modulating the function of other membrane proteins such as G protein coupled receptors and ion channels. Several ligands targeting this receptor are currently in clinical trials for the treatment of Alzheimer's disease, ischemic stroke and neuro-pathic pain. Hence, this receptor has emerged as an attractive target for the treatment of neuro-pathological diseases with unmet medical needs. It is of interest to identify and characterise novelσ1 receptor ligands with different chemical scaffolds using computer-aided drug designing approach. In this work, a GPCR-focused chemical library consisting of 8543 compounds was screened by pharmacophore and docking-based virtual screening methods using LigandScout 4.3 and Autodock Vina 1.1.2 in PyRx 0.8, respectively. The pharmacophore model was constructed based on the interactions of a selective agonist and another antagonist ligand with high binding affinity to the human σ1receptors. Candidate compounds were filtered sequentially by pharmacophore-fit scores, docking energy scores, drug-likeness filters and ADMET properties. The binding mode and pharmacophore mapping of candidate compounds were analysed by Autodock Vina 1.1.2 and LigandScout 4.3 programs, respectively. A pharmacophore model composed of three hydrophobic and positive ionizable features with recognized geometry was built and used as a 3D query for screening a GPCR-focused chemical library by LigandScout 4.3 program. Among the screened 8543 compounds, 159 candidate compounds were obtained from pharmacophore-based screening. 45 compounds among them bound to σ 1receptor with high binding-affinity scores in comparison to the co-crystallized ligand. Amongst these, top five candidate compounds with excellent druglikeness and ADMET properties were selected. These five candidate compounds may act as potential σ1 receptor ligands.
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Affiliation(s)
- Mubarak A Alamri
- Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
| | - Mohammed A Alamri
- Department of Pharmacology, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
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5
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Vavers E, Zvejniece L, Maurice T, Dambrova M. Allosteric Modulators of Sigma-1 Receptor: A Review. Front Pharmacol 2019; 10:223. [PMID: 30941035 PMCID: PMC6433746 DOI: 10.3389/fphar.2019.00223] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/22/2019] [Indexed: 11/13/2022] Open
Abstract
Allosteric modulators of sigma-1 receptor (Sig1R) are described as compounds that can increase the activity of some Sig1R ligands that compete with (+)-pentazocine, one of the classic prototypical ligands that binds to the orthosteric Sig1R binding site. Sig1R is an endoplasmic reticulum membrane protein that, in addition to its promiscuous high-affinity ligand binding, has been shown to have chaperone activity. Different experimental approaches have been used to describe and validate the activity of allosteric modulators of Sig1R. Sig1R-modulatory activity was first found for phenytoin, an anticonvulsant drug that primarily acts by blocking the voltage-gated sodium channels. Accumulating evidence suggests that allosteric Sig1R modulators affect processes involved in the pathophysiology of depression, memory and cognition disorders as well as convulsions. This review will focus on the description of selective and non-selective allosteric modulators of Sig1R, including molecular structure properties and pharmacological activity both in vitro and in vivo, with the aim of providing the latest overview from compound discovery approaches to eventual clinical applications. In this review, the possible mechanisms of action will be discussed, and future challenges in the development of novel compounds will be addressed.
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Affiliation(s)
- Edijs Vavers
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Liga Zvejniece
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Tangui Maurice
- MMDN, University of Montpellier, INSERM, EPHE, UMR-S1198, Montpellier, France
| | - Maija Dambrova
- Laboratory of Pharmaceutical Pharmacology, Latvian Institute of Organic Synthesis, Riga, Latvia
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6
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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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7
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Tesei A, Cortesi M, Zamagni A, Arienti C, Pignatta S, Zanoni M, Paolillo M, Curti D, Rui M, Rossi D, Collina S. Sigma Receptors as Endoplasmic Reticulum Stress "Gatekeepers" and their Modulators as Emerging New Weapons in the Fight Against Cancer. Front Pharmacol 2018; 9:711. [PMID: 30042674 PMCID: PMC6048940 DOI: 10.3389/fphar.2018.00711] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 06/12/2018] [Indexed: 12/13/2022] Open
Abstract
Despite the interest aroused by sigma receptors (SRs) in the area of oncology, their role in tumor biology remains enigmatic. The predominant subcellular localization and main site of activity of SRs are the endoplasmic reticulum (ER). Current literature data, including recent findings on the sigma 2 receptor subtype (S2R) identity, suggest that SRs may play a role as ER stress gatekeepers. Although SR endogenous ligands are still unknown, a wide series of structurally unrelated compounds able to bind SRs have been identified. Currently, the identification of novel antiproliferative molecules acting via SR interaction is a challenging task for both academia and industry, as shown by the fact that novel anticancer drugs targeting SRs are in the preclinical-stage pipeline of pharmaceutical companies (i.e., Anavex Corp. and Accuronix). So far, no clinically available anticancer drugs targeting SRs are still available. The present review focuses literature advancements and provides a state-of-the-art overview of SRs, with emphasis on their involvement in cancer biology and on the role of SR modulators as anticancer agents. Findings from preclinical studies on novel anticancer drugs targeting SRs are presented in brief.
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Affiliation(s)
- Anna Tesei
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Michela Cortesi
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Alice Zamagni
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Chiara Arienti
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Sara Pignatta
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Michele Zanoni
- Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRCCS), Meldola, Italy
| | - Mayra Paolillo
- Pharmacology Section, Department of Drug Sciences, University of Pavia, Pavia, Italy
| | - Daniela Curti
- Laboratory of Cellular and Molecular Neuropharmacology, Department of Biology and Biotechnology 'L. Spallanzani', University of Pavia, Pavia, Italy
| | - Marta Rui
- Medicinal Chemistry and Pharmaceutical Technology Section, Department of Drug Sciences, University of Pavia, Pavia, Italy
| | - Daniela Rossi
- Medicinal Chemistry and Pharmaceutical Technology Section, Department of Drug Sciences, University of Pavia, Pavia, Italy
| | - Simona Collina
- Medicinal Chemistry and Pharmaceutical Technology Section, Department of Drug Sciences, University of Pavia, Pavia, Italy
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8
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Abstract
A complex PGRMC1-centred regulatory system controls multiple cell functions. Although PGRMC1 is phosphorylated at several positions, we do not understand the mechanisms regulating its function. PGRMC1 is the archetypal member of the membrane associated progesterone receptor (MAPR) family. Phylogentic comparison of MAPR proteins suggests that the ancestral metazoan "PGRMC-like" MAPR gene resembled PGRMC1/PGRMC2, containing the equivalents of PGRMC1 Y139 and Y180 SH2 target motifs. It later acquired a CK2 site with phosphoacceptor at S181. Separate PGRMC1 and PGRMC2 genes with this "PGRMC-like" structure diverged after the separation of vertebrates from protochordates. Terrestrial tetrapods possess a novel proline-rich PGRMC1 SH3 target motif centred on P64 which in mammals is augmented by a phosphoacceptor at PGRMC1 S54, and in primates by an additional S57 CK2 site. All of these phosphoacceptors are phosphorylated in vivo. This study suggests that an increasingly sophisticated system of PGRMC1-modulated multicellular functional regulation has characterised animal evolution since Precambrian times.
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9
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Abstract
Sigma1 (also known as sigma-1 receptor, Sig1R, σ1 receptor) is a unique pharmacologically regulated integral membrane chaperone or scaffolding protein. The majority of publications on the subject have focused on the neuropharmacology of Sigma1. However, a number of publications have also suggested a role for Sigma1 in cancer. Although there is currently no clinically used anti-cancer drug that targets Sigma1, a growing body of evidence supports the potential of Sigma1 ligands as therapeutic agents to treat cancer. In preclinical models, compounds with affinity for Sigma1 have been reported to inhibit cancer cell proliferation and survival, cell adhesion and migration, tumor growth, to alleviate cancer-associated pain, and to have immunomodulatory properties. This review will highlight that although the literature supports a role for Sigma1 in cancer, several fundamental questions regarding drug mechanism of action and the physiological relevance of aberrant SIGMAR1 transcript and Sigma1 protein expression in certain cancers remain unanswered or only partially answered. However, emerging lines of evidence suggest that Sigma1 is a component of the cancer cell support machinery, that it facilitates protein interaction networks, that it allosterically modulates the activity of its associated proteins, and that Sigma1 is a selectively multifunctional drug target.
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Affiliation(s)
- Felix J Kim
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA, USA.
- Sidney Kimmel Cancer Center, Philadelphia, PA, USA.
| | - Christina M Maher
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA, USA
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10
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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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Yasui Y, Su TP. Potential Molecular Mechanisms on the Role of the Sigma-1 Receptor in the Action of Cocaine and Methamphetamine. ACTA ACUST UNITED AC 2016; 5. [PMID: 27088037 DOI: 10.4303/jdar/235970] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum membrane protein that involves a wide range of physiological functions. The Sig-1R has been shown to bind psychostimulants including cocaine and methamphetamine (METH) and thus has been implicated in the actions of those psychostimulants. For example, it has been demonstrated that the Sig-1R antagonists mitigate certain behavioral and cellular effects of psychostimulants including hyperactivity and neurotoxicity. Thus, the Sig-1R has become a potential therapeutic target of medication development against drug abuse that differs from traditional monoamine-related strategies. In this review, we will focus on the molecular mechanisms of the Sig-1R and discuss in such a manner with a hope to further understand or unveil unexplored relations between the Sig-1R and the actions of cocaine and METH, particularly in the context of cellular biological relevance.
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Affiliation(s)
- Yuko Yasui
- Cellular Pathobiology Section, Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, Maryland 21224
| | - Tsung-Ping Su
- Cellular Pathobiology Section, Integrative Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, Maryland 21224
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12
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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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13
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Mishra AK, Mavlyutov T, Singh DR, Biener G, Yang J, Oliver JA, Ruoho A, Raicu V. The sigma-1 receptors are present in monomeric and oligomeric forms in living cells in the presence and absence of ligands. Biochem J 2015; 466:263-271. [PMID: 25510962 PMCID: PMC4500508 DOI: 10.1042/bj20141321] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The sigma-1 receptor (S1R) is a 223-amino-acid membrane protein that resides in the endoplasmic reticulum and the plasma membrane of some mammalian cells. The S1R is regulated by various synthetic molecules including (+)-pentazocine, cocaine and haloperidol and endogenous molecules such as sphingosine, dimethyltryptamine and dehydroepiandrosterone. Ligand-regulated protein chaperone functions linked to oxidative stress and neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) and neuropathic pain have been attributed to the S1R. Several client proteins that interact with S1R have been identified including various types of ion channels and G-protein coupled receptors (GPCRs). When S1R constructs containing C-terminal monomeric GFP2 and YFP fusions were co-expressed in COS-7 cells and subjected to FRET spectrometry analysis, monomers, dimers and higher oligomeric forms of S1R were identified under non-liganded conditions. In the presence of the prototypic S1R agonist, (+)-pentazocine, however, monomers and dimers were the prevailing forms of S1R. The prototypic antagonist, haloperidol, on the other hand, favoured higher order S1R oligomers. These data, in sum, indicate that heterologously expressed S1Rs occur in vivo in COS-7 cells in multiple oligomeric forms and that S1R ligands alter these oligomeric structures. We suggest that the S1R oligomerization states may regulate its function(s).
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Affiliation(s)
- Ashish K. Mishra
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Timur Mavlyutov
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Deo R. Singh
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Jay Yang
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Julie A. Oliver
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Arnold Ruoho
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
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14
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Gromek KA, Suchy FP, Meddaugh HR, Wrobel RL, LaPointe LM, Chu UB, Primm JG, Ruoho AE, Senes A, Fox BG. The oligomeric states of the purified sigma-1 receptor are stabilized by ligands. J Biol Chem 2014; 289:20333-44. [PMID: 24847081 PMCID: PMC4106346 DOI: 10.1074/jbc.m113.537993] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 04/29/2014] [Indexed: 12/05/2022] Open
Abstract
Sigma-1 receptor (S1R) is a mammalian member of the ERG2 and sigma-1 receptor-like protein family (pfam04622). It has been implicated in drug addiction and many human neurological disorders, including Alzheimer and Parkinson diseases and amyotrophic lateral sclerosis. A broad range of synthetic small molecules, including cocaine, (+)-pentazocine, haloperidol, and small endogenous molecules such as N,N-dimethyltryptamine, sphingosine, and steroids, have been identified as regulators of S1R. However, the mechanism of activation of S1R remains obscure. Here, we provide evidence in vitro that S1R has ligand binding activity only in an oligomeric state. The oligomeric state is prone to decay into an apparent monomeric form when exposed to elevated temperature, with loss of ligand binding activity. This decay is suppressed in the presence of the known S1R ligands such as haloperidol, BD-1047, and sphingosine. S1R has a GXXXG motif in its second transmembrane region, and these motifs are often involved in oligomerization of membrane proteins. Disrupting mutations within the GXXXG motif shifted the fraction of the higher oligomeric states toward smaller states and resulted in a significant decrease in specific (+)-[(3)H]pentazocine binding. Results presented here support the proposal that S1R function may be regulated by its oligomeric state. Possible mechanisms of molecular regulation of interacting protein partners by S1R in the presence of small molecule ligands are discussed.
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Affiliation(s)
| | | | | | | | | | - Uyen B Chu
- Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | | | - Arnold E Ruoho
- Neuroscience, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | | | - Brian G Fox
- From the Transmembrane Protein Center, Departments of Biochemistry and
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15
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Gromek KA, Meddaugh HR, Wrobel RL, Suchy FP, Bingman CA, Primm JG, Fox BG. Improved expression and purification of sigma 1 receptor fused to maltose binding protein by alteration of linker sequence. Protein Expr Purif 2013; 89:203-9. [PMID: 23562661 PMCID: PMC3679933 DOI: 10.1016/j.pep.2013.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/21/2013] [Accepted: 03/25/2013] [Indexed: 01/29/2023]
Abstract
Sigma 1 receptor (S1R) is a eukaryotic membrane protein that functions as an inter-organelle signaling modulator and chaperone. Here we report an improved expression of S1R in Escherichia coli as a fusion to maltose binding protein (MBP) and a high-yield purification. Variants with linking amino acid sequences consisting of 0-5 alanine residues between MBP and S1R were created and tested in several E. coli expression strains in order to determine the best combination of construct and host for production of active MBP-S1R. Among the linker variations, the protein containing a 4-Ala linker exhibited superior expression characteristics (MBP-4A-S1R); this construct was most productively paired with E. coli B834-pRARE2 and a chemically defined growth and expression medium. A 3-step purification was developed, including extraction from the E. coli membrane fraction using a mixture of Triton X-100 and n-dodecyl-beta-D-maltopyranoside identified by screening constrainted by retention of binding function, and purification by amylose affinity and gel filtration chromatographies. This procedure yields ∼3.5mg of purified fusion protein per L of bacterial culture medium. Purified MBP-4A-S1R showed a 175-fold purification from the starting cellular lysate with respect to specific ligand binding activity, and is stable during concentration and freeze-thaw cycling.
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Affiliation(s)
- Katarzyna A. Gromek
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Hannah R. Meddaugh
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Russell L. Wrobel
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Fabian P. Suchy
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Craig A. Bingman
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - John G. Primm
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Brian G. Fox
- Transmembrane Protein Center (TMPC), Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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16
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Marriott KSC, Prasad M, Thapliyal V, Bose HS. σ-1 receptor at the mitochondrial-associated endoplasmic reticulum membrane is responsible for mitochondrial metabolic regulation. J Pharmacol Exp Ther 2012; 343:578-86. [PMID: 22923735 PMCID: PMC3500540 DOI: 10.1124/jpet.112.198168] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/23/2012] [Indexed: 01/30/2023] Open
Abstract
The mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) is a small section of the outer mitochondrial membrane tethered to the ER by lipid and protein filaments. One such MAM protein is the σ-1 receptor, which contributes to multiple signaling pathways. We found that short interfering RNA-mediated knockdown of σ-1 reduced pregnenolone synthesis by 95% without affecting expression of the inner mitochondrial membrane resident enzyme, 3-β-hydroxysteroid dehydrogenase 2. To explore the underlying mechanism of this effect, we generated a series of σ-receptor ligands: 5,6-dimethoxy-3-methyl-N-phenyl-N-(3-(piperidin-1-yl)propyl)benzofuran-2-carboxamide (KSCM-1), 3-methyl-N-phenyl-N-(3-(piperidin-1-yl)propyl)benzofuran-2-carboxamide (KSCM-5), and 6-methoxy-3-methyl-N-phenyl-N-(3-(piperidin-1-yl) propyl)benzofuran-2-carboxamide (KSCM-11) specifically bound to σ-1 in the nanomolar range, whereas KSCM-5 and KSCM-11 also bound to σ-2. Treatment of cells with the KSCM ligands led to decreased cell viability, with KSCM-5 having the most potent effect followed by KSCM-11. KSCM-1 increased σ-1 expression by 4-fold and progesterone synthesis, whereas the other compounds decreased progesterone synthesis. These differences probably are caused by ligand molecular structure. For example, KSCM-1 has two methoxy substituents at C-5 and C-6 of the benzofuran ring, whereas KSCM-11 has one at C-6. KSCM ligands or σ-1 knockdown did not alter the expression of ER resident enzymes that synthesize steroids. However, coimmunoprecipitation of the σ-1 receptor pulled down voltage-dependent anion channel 2 (VDAC2), whose expression was enhanced by KSCM-1. VDAC2 plays a key role in cholesterol transport into the mitochondria, suggesting that the σ-1 receptor at the MAM coordinates with steroidogenic acute regulatory protein for cholesterol trafficking into the mitochondria for metabolic regulation.
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Affiliation(s)
- Karla-Sue C Marriott
- Department of Natural Sciences, College of Science and Technology, Savannah State University, Savannah, GA, USA
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17
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Marriott KSC, Morrison AZ, Moore M, Olubajo O, Stewart LE. Synthesis of N-phenyl-N-(3-(piperidin-1-yl)propyl)benzofuran-2-carboxamides as new selective ligands for sigma receptors. Bioorg Med Chem 2012; 20:6856-61. [PMID: 23084435 PMCID: PMC3490055 DOI: 10.1016/j.bmc.2012.09.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 09/12/2012] [Accepted: 09/19/2012] [Indexed: 11/19/2022]
Abstract
Novel benzofuran-2-carboxamide ligands, which are selective for sigma receptors, have been synthesized via a microwave-assisted Perkin rearrangement reaction and a modified Finkelstein halogen-exchange used to facilitate N-alkylation. The ligands synthesized are the 3-methyl-N-phenyl-N-(3-(piperidin-1-yl)propyl)benzofuran-2-carboxamides (KSCM-1, KSCM-5 and KSCM-11). The benzofuran-2-carboxamide structure was N-arylated and N-alkylated to include both N-phenyl and N-(3-(piperidin-1-yl)propyl substituents, respectively. These new carboxamides exhibit high affinity at the sigma-1 receptor with K(i) values ranging from 7.8 to 34nM. Ligand KSCM-1 with two methoxy substituents at C-5 and C-6 of the benzofuran ring, and K(i)=27.5nM at sigma-1 was found to be more selective for sigma-1 over sigma-2.
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Affiliation(s)
- Karla-Sue C Marriott
- Department of Natural Sciences, Savannah State University, College of Sciences and Technology, Savannah, Georgia 31404, USA.
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18
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Martin-Fardon R, Strong EM, Weiss F. Effect of σ1 receptor antagonism on ethanol and natural reward seeking. Neuroreport 2012; 23:809-13. [DOI: 10.1097/wnr.0b013e32835717c8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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19
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Kim FJ, Schrock JM, Spino CM, Marino JC, Pasternak GW. Inhibition of tumor cell growth by Sigma1 ligand mediated translational repression. Biochem Biophys Res Commun 2012; 426:177-82. [PMID: 22925888 PMCID: PMC3480203 DOI: 10.1016/j.bbrc.2012.08.052] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Accepted: 08/13/2012] [Indexed: 01/08/2023]
Abstract
Treatment with sigma1 receptor (Sigma1) ligands can inhibit cell proliferation in vitro and tumor growth in vivo. However, the cellular pathways engaged in response to Sigma1 ligand treatment that contribute to these outcomes remain largely undefined. Here, we show that treatment with putative antagonists of Sigma1 decreases cell mass. This effect corresponds with repressed cap-dependent translation initiation in multiple breast and prostate cancer cell lines. Sigma1 antagonist treatment suppresses phosphorylation of translational regulator proteins p70S6K, S6, and 4E-BP1. RNAi-mediated knockdown of Sigma1 also results in translational repression, consistent with the effects of antagonist treatment. Sigma1 antagonist mediated translational repression and decreased cell size are both reversible. Together, these data reveal a role for Sigma1 in tumor cell protein synthesis, and demonstrate that small molecule Sigma1 ligands can be used as modulators of protein translation.
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Affiliation(s)
- Felix J Kim
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102-1192, USA.
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20
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Yarim M, Koksal M, Schepmann D, Wünsch B. Synthesis and in vitro Evaluation of Novel Indole-Based Sigma Receptors Ligands. Chem Biol Drug Des 2011; 78:869-75. [DOI: 10.1111/j.1747-0285.2011.01215.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Abstract
Sigma receptors (σ-1 and σ-2) are non-opioid proteins implicated in the pathophysiology of various neurological disorders and cancer. The σ-1 subtype is a chaperon protein widely distributed in the CNS and peripheral tissues. These receptors are involved in the modulation of K+- and Ca2+-dependent signaling cascades at the endoplasmic reticulum and modulation of neurotransmitter release. σ-1 receptors are emerging targets for the treatment of neurophychiatric diseases (schizophrenia and depression) and cocaine addiction. σ-2 receptors are lipid raft proteins. They are highly expressed on many tumor cells and hence considered potential targets for anticancer drugs. σ receptors bind to a diverse class of pharmacological compounds like cocaine, methamphetamine, benzomorphans like (±)-pentazocine, (±)-SKF-10,047 and endogenous neurosteroids and sphingolipids. In this review we focus on the early development of σ receptor-specific ligands and radiolabeling agents.
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22
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Su TP, Hayashi T, Maurice T, Buch S, Ruoho AE. The sigma-1 receptor chaperone as an inter-organelle signaling modulator. Trends Pharmacol Sci 2010; 31:557-66. [PMID: 20869780 PMCID: PMC2993063 DOI: 10.1016/j.tips.2010.08.007] [Citation(s) in RCA: 359] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/19/2010] [Accepted: 08/26/2010] [Indexed: 01/13/2023]
Abstract
Inter-organelle signaling plays important roles in many physiological functions. Endoplasmic reticulum (ER)-mitochondrion signaling affects intramitochondrial calcium (Ca(2+)) homeostasis and cellular bioenergetics. ER-nucleus signaling attenuates ER stress. ER-plasma membrane signaling regulates cytosolic Ca(2+) homeostasis and ER-mitochondrion-plasma membrane signaling regulates hippocampal dendritic spine formation. Here, we propose that the sigma-1 receptor (Sig-1R), an ER chaperone protein, acts as an inter-organelle signaling modulator. Sig-1Rs normally reside at the ER-mitochondrion contact called the MAM (mitochondrion-associated ER membrane), where Sig-1Rs regulate ER-mitochondrion signaling and ER-nucleus crosstalk. When cells are stimulated by ligands or undergo prolonged stress, Sig-1Rs translocate from the MAM to the ER reticular network and plasmalemma/plasma membrane to regulate a variety of functional proteins, including ion channels, receptors and kinases. Thus, the Sig-1R serves as an inter-organelle signaling modulator locally at the MAM and remotely at the plasmalemma/plasma membrane. Many pharmacological/physiological effects of Sig-1Rs might relate to this unique action of Sig-1Rs.
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Affiliation(s)
- Tsung-Ping Su
- Cellular Pathobiology Section, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, suite 3304, 333 Cassell Drive, Baltimore, MD 21224, USA.
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23
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Megalizzi V, Le Mercier M, Decaestecker C. Sigma receptors and their ligands in cancer biology: overview and new perspectives for cancer therapy. Med Res Rev 2010; 32:410-27. [DOI: 10.1002/med.20218] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Marie Le Mercier
- Department of Pathology; Erasme University Hospital; Brussels Belgium
| | - Christine Decaestecker
- Laboratory of Toxicology; Institute of Pharmacy; Brussels Belgium
- Laboratory of Image Synthesis and Analysis; Faculty of Applied Sciences; Université Libre de Bruxelles (ULB); Brussels Belgium
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24
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Hayashi T, Su T. The sigma receptor: evolution of the concept in neuropsychopharmacology. Curr Neuropharmacol 2010; 3:267-80. [PMID: 18369400 DOI: 10.2174/157015905774322516] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Accepted: 06/17/2005] [Indexed: 11/22/2022] Open
Abstract
Although originally proposed as a subtype of opioid receptors, the sigma receptor is now confirmed to be a non-opioid receptor that binds diverse classes of psychotropic drugs. Sigma receptors are subdivided into two subtypes, sigma-1 and sigma-2. The sigma-1 receptor is a 25-kDa protein possessing one putative transmembrane domain and an endoplasmic reticulum retention signal. Sigma-1 receptors are highly expressed in deeper laminae of the cortex, olfactory bulb, nuclei of mesencephalon, hypothalamus, and Purkinje cells in the brain. Sigma-1 receptors are predominantly localized at the endoplasmic reticulum of both neurons and oligodendrocytes. From behavioral studies, sigma-1 receptors were shown to be involved in higher-ordered brain functions including memory and drug dependence. The actions mediated by sigma-1 receptors at the cellular level can be considered either as acute or chronic. The acute actions include the modulation of ion channels (i.e., K+ channel, NMDA receptors, IP3 receptors) and the sigma-1 receptor translocation. Chronic actions of sigma-1 receptors are basically considered to be the result of an up- or down regulation of the sigma-1 receptor itself. For example, the upregulation of sigma-1 receptors per se, even without exogenous ligands, promotes cellular differentiation and reconstitution of lipid microdomains (lipid rafts) in cultured cells. These findings together suggest that sigma-1 receptors might possess a constitutive biological activity, and that sigma-1 receptor ligands might merely work as modulators of the innate activity of this protein. Recent in vitro and in vitro studies strongly point to the possibility that sigma-1 receptors participate in membrane remodeling and cellular differentiation in the nervous system.
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Affiliation(s)
- T Hayashi
- Cellular Pathobiology Unit/DPS, Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, DHHS., 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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Lee IT, Chen S, Schetz JA. An unambiguous assay for the cloned human sigma1 receptor reveals high affinity interactions with dopamine D4 receptor selective compounds and a distinct structure-affinity relationship for butyrophenones. Eur J Pharmacol 2008; 578:123-36. [PMID: 17961544 PMCID: PMC2963108 DOI: 10.1016/j.ejphar.2007.09.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 09/11/2007] [Accepted: 09/23/2007] [Indexed: 11/15/2022]
Abstract
The ability of the sigma(1) receptor to interact with a huge range of drug structural classes coupled with its wide distribution in the body has contributed to it being implicated as a possible therapeutic target for a broad array of disorders ranging from substance abuse to depression to Alzheimer's disease. Surprisingly, the reported affinity values for some sigma(1) receptor ligands vary more than 50-fold. The potential of the sigma(1) receptor as a pharmacotherapeutic target prompted us to develop an unambiguous assay system for measuring the affinity of ligands to the cloned human sigma(1) receptor. In the course of characterizing this system and determining the true affinity values for almost three dozen compounds, it was discovered that some dopamine D(4) receptor selective compounds bind sigma(1) receptors with high affinity. A systematic analysis of haloperidol-like compounds revealed a clear structure-affinity relationship amongst clinically relevant butyrophenones. The antidepressant fluvoxamine, the drug of abuse methamphetamine, and the neurosteroid progesterone were amongst the many ligands whose interactions with the sigma(1) receptor were confirmed with our screening assay.
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Affiliation(s)
- Ivan T. Lee
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
| | - Shiuhwei Chen
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
| | - John A. Schetz
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
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26
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A Botrytis cinerea emopamil binding domain protein, required for full virulence, belongs to a eukaryotic superfamily which has expanded in euascomycetes. EUKARYOTIC CELL 2007; 7:368-78. [PMID: 18156289 DOI: 10.1128/ec.00159-07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A previous transcriptomic analysis of 3,032 fungal genes identified the Botrytis cinerea PIE3 (BcPIE3) gene to be up-regulated early in planta (A. Gioti, A. Simon, P. Le Pêcheur, C. Giraud, J. M. Pradier, M. Viaud, and C. Levis, J. Mol. Biol. 358:372-386, 2006). In the present study, BcPIE3 was disrupted in order to determine its implication in pathogenicity. BcPIE3 was shown to be a virulence factor, since the DeltaBcPIE3 mutant was blocked during the colonization of tomato and bean leaves, giving lesions reduced in size by at least 74%. Within the emopamil binding domain (EBD), BcPIE3 shows significant structural similarities to mammalian emopamil binding proteins (EBPs). Mammalian EBPs function as sterol isomerases, but an analysis of the sterol content and the results of growth inhibition experiments with the DeltaBcPIE3 strain indicated that BcPIE3 is dispensable for ergosterol biosynthesis. The systematic identification of EBD-containing proteins included in public databases showed that these proteins constitute a protein superfamily present only in eukaryotes. Phylogenetic analysis showed that the ancestral EBD-encoding gene was duplicated in the common ancestor of animals and fungi after the split from plants. Finally, we present evidence that the EBP phylogenetic clade of this superfamily has further expanded exclusively in euascomycetes, especially in B. cinerea, which contains three copies of the EBP gene.
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Wang J, Mack AL, Coop A, Matsumoto RR. Novel sigma (sigma) receptor agonists produce antidepressant-like effects in mice. Eur Neuropsychopharmacol 2007; 17:708-16. [PMID: 17376658 PMCID: PMC4041597 DOI: 10.1016/j.euroneuro.2007.02.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Revised: 01/12/2007] [Accepted: 02/06/2007] [Indexed: 01/25/2023]
Abstract
Many antidepressant drugs interact with sigma receptors and accumulating evidence suggests that these proteins mediate antidepressant-like effects in animals and humans. sigma Receptors are localized in brain regions affected in depression, further strengthening the hypothesis that they represent logical drug development targets. In this study, two novel sigma receptor agonists (UMB23, UMB82) were evaluated for antidepressant-like activity in mice. First, radioligand binding studies confirmed that the novel compounds had preferential affinity for sigma receptors. Second, the forced swim test, a well established animal model for screening potential antidepressant drugs, showed that both compounds dose-dependently reduced immobility time. The sigma receptor antagonist BD1047 attenuated the antidepressant-like effects of UMB23 and UMB82. Third, locomotor activity suggested that the effects of UMB23 and UMB82 in the forced swim test were not due to non-specific motor activating effects. Together, the data provide further evidence that sigma receptor agonists represent a possible new class of antidepressant medication.
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Affiliation(s)
- Jiajia Wang
- Department of Pharmacology, University of Mississippi, University, MS 38677 USA
| | - Aisha L. Mack
- Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190 USA
| | - Andrew Coop
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201 USA
| | - Rae R. Matsumoto
- Department of Pharmacology, University of Mississippi, University, MS 38677 USA
- Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190 USA
- Corresponding author: Rae R. Matsumoto, Ph.D., Department of Pharmacology, School of Pharmacy, University of Mississippi, 303 Faser Hall, University, MS 38677. Telephone: +1-662-915-1466; Fax: +1-662-915-5148;
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Pal A, Hajipour AR, Fontanilla D, Ramachandran S, Chu UB, Mavlyutov T, Ruoho AE. Identification of regions of the sigma-1 receptor ligand binding site using a novel photoprobe. Mol Pharmacol 2007; 72:921-33. [PMID: 17622576 DOI: 10.1124/mol.107.038307] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
sigma Receptors, once considered a class of opioid receptors, are now regarded as a unique class of receptors that contain binding sites for a wide range of ligands, including the drug 1-N(2',6'-dimethylmorpholino)3-(4-t-butylpropylamine) (fenpropimorph), a yeast sterol isomerase inhibitor. Because fenpropimorph has high-binding affinity to the sigma-1 receptor, we have synthesized a series of fenpropimorph-like derivatives with varying phenyl ring substituents and have characterized their binding affinities to the sigma-1 receptor. In addition, we have synthesized a carrier-free, radioiodinated fenpropimorph-like photoaffinity label, 1-N-(2',6'-dimethyl-morpholino)-3-(4-azido-3-[(125)I]iodo-phenyl)propane ([(125)I]IAF), which covalently derivatized the sigma-1 receptor (25.3 kDa) in both the rat liver and guinea pig liver membranes and the sigma-2 receptor (18 kDa) in rat liver membranes with high specificity. Furthermore, after cleaving the specific [(125)I]IAF-photolabeled sigma-1 receptor in guinea pig and rat liver membranes and the pure guinea pig sigma-1 receptor with EndoLys-C and cyanogen bromide, the [(125)I]IAF label was identified both in a peptide containing steroid binding domain-like I (SBDLI) (amino acids 91-109) and in a peptide containing steroid binding domain-like II (SBDLII) (amino acids 176-194). Because a single population of binding sites (R(2) = 0.992) for [(125)I]IAF interaction with the sigma-1 receptor was identified by (+)-[(3)H]pentazocine competitive binding with nonradioactive [(127)I]IAF, it was concluded that SBDLI (amino acids 91-109) and SBDLII (amino acids 176-194) comprises, at least in part, regions of the sigma-1 receptor ligand binding site(s).
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Affiliation(s)
- Arindam Pal
- Department of Pharmacology, University of Wisconsin Medical School, 1300 University Avenue, Madison, WI 53706, USA
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29
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Chen Y, Hajipour AR, Sievert MK, Arbabian M, Ruoho AE. Characterization of the cocaine binding site on the sigma-1 receptor. Biochemistry 2007; 46:3532-42. [PMID: 17315983 DOI: 10.1021/bi061727o] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cocaine photoaffinity label 3-iodo-4-azidococaine ([125I]IACoc) binds to the sigma-1 receptor with an affinity that is 2-3 orders of magnitude higher than the parent compound cocaine [Kahoun, J. R., and Ruoho, A. E. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 1393-1397]. In the present study, the binding properties of several cocaine derivatives to the guinea pig liver sigma-1 receptor were determined. The results from assessing the affinity of various derivatives of cocaine which were substituted on the phenyl ring indicated that an important determinant of binding to the guinea pig sigma-1 receptor binding site may be the development of a dipole in the ring in which the pi electron density of the phenyl ring is reduced. This implies that an electron-rich source is present in the sigma-1 receptor binding site, such as the pi system of an aromatic ring or other electron-rich side chains, which interact with the phenyl ring of cocaine. The precise [125I]IACoc derivatization site in the guinea pig sigma-1 receptor was identified using chemical cleavage and purification of the resulting labeled peptides. Cyanogen bromide cleavage of the [125I]IACoc photolabeled sigma-1 receptor followed by radiosequencing identified Asp188, which is located in the putative steroid binding domain-like II (SBDL II) near the carboxyl terminus, as the site of [125I]IACoc insertion. Systematic truncation of the C-terminus indicated the requirement for the last 15 amino acid residues of the receptor for [125I]IACoc photolabeling.
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Affiliation(s)
- Yuenmu Chen
- Department of Pharmacology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, Wisconsin 53706-1532, USA
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Renaudo A, L'Hoste S, Guizouarn H, Borgèse F, Soriani O. Cancer cell cycle modulated by a functional coupling between sigma-1 receptors and Cl- channels. J Biol Chem 2007; 282:2259-67. [PMID: 17121836 DOI: 10.1074/jbc.m607915200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sigma-1 receptor is an intracellular protein characterized as a tumor biomarker whose function remains mysterious. We demonstrate herein for the first time that highly selective sigma ligands inhibit volume-regulated chloride channels (VRCC) in small cell lung cancer and T-leukemia cells. Sigma ligands and VRCC blockers provoked a cell cycle arrest underlined by p27 accumulation. In stably sigma-1 receptor-transfected HEK cells, the proliferation rate was significantly lowered by sigma ligands when compared with control cells. Sigma ligands produced a strong inhibition of VRCC in HEK-transfected cells but not in control HEK. Surprisingly, the activation rate of VRCC was dramatically delayed in HEK-transfected cells in the absence of ligands, indicating that sigma-1 receptors per se modulate cell regulating volume processes in physiological conditions. Volume measurements in hypotonic conditions revealed indeed that the regulatory volume decrease was delayed in HEK-transfected cells and virtually abolished in the presence of igmesine in both HEK-transfected and T-leukemic cells. Moreover, HEK-transfected cells showed a significant resistance to staurosporine-induced apoptosis volume decrease, indicating that sigma-1 receptors protect cancer cells from apoptosis. Altogether, our results show for the first time that sigma-1 receptors modulate "cell destiny" through VRCC and cell volume regulation.
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Affiliation(s)
- Adrien Renaudo
- UNSA CNRS UMR 6548, Laboratoire de Physiologie Cellulaire & Moléculaire des Systèmes Intégrés, Université de Nice Sophia-Antipolis, 06108 Nice Cedex 2, France
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Martina M, Turcotte MEB, Halman S, Bergeron R. The sigma-1 receptor modulates NMDA receptor synaptic transmission and plasticity via SK channels in rat hippocampus. J Physiol 2007; 578:143-57. [PMID: 17068104 PMCID: PMC2075134 DOI: 10.1113/jphysiol.2006.116178] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Accepted: 10/25/2006] [Indexed: 02/01/2023] Open
Abstract
The sigma receptor (sigmaR), once considered a subtype of the opioid receptor, is now described as a distinct pharmacological entity. Modulation of N-methyl-D-aspartate receptor (NMDAR) functions by sigmaR-1 ligands is well documented; however, its mechanism is not fully understood. Using patch-clamp whole-cell recordings in CA1 pyramidal cells of rat hippocampus and (+)pentazocine, a high-affinity sigmaR-1 agonist, we found that sigmaR-1 activation potentiates NMDAR responses and long-term potentiation (LTP) by preventing a small conductance Ca2+-activated K+ current (SK channels), known to shunt NMDAR responses, to open. Therefore, the block of SK channels and the resulting increased Ca2+ influx through the NMDAR enhances NMDAR responses and LTP. These results emphasize the importance of the sigmaR-1 as postsynaptic regulator of synaptic transmission.
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Affiliation(s)
- Marzia Martina
- Department of Cellular and Molecular Medicine, Ottawa Health Research Institute, 725 Parkdale Avenue, Ottawa, Ontario, K1Y 4E9, Canada.
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Abstract
The sigma (sigma) receptor and its agonists have been implicated in a myriad of cellular functions, biological processes and diseases. Whereas the precise molecular mechanism(s) of sigma receptors and their involvement in cancer cell biology have not been elucidated, recent work has started to shed some light on these issues. A molecular model has been proposed for the cloned sigma1 receptor; the precise molecular nature of the sigma2 receptor remains unknown. sigma receptors have been found to be frequently up-regulated in human cancer cells and tissues. sigma2 receptor drugs particularly have been shown to have antiproliferative effects. An interesting possibility is that sigma and/or sigma1 drugs could produce anticancerous effects by modulating ion channels. As well as proliferation, a variety of other metastatic cellular behaviors such as adhesion, motility, and secretion may also be affected. Other mechanisms of sigma receptor action may involve interaction with ankyrin and modulation of intracellular Ca(2+) and sphingolipid levels. Although more research is needed to further define the molecular physiology of sigma receptors, their involvement in the cellular pathophysiology of cancer raises the possibility that sigma drugs could be useful as novel therapeutic agents.
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Affiliation(s)
- Ebru Aydar
- Department of Biological Sciences, Sir Alexander Fleming Building, Imperial College, South Kensington Campus, London SW7 2AZ, United Kingdom.
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Gund TM, Floyd J, Jung D. Molecular modeling of sigma 1 receptor ligands: a model of binding conformational and electrostatic considerations. J Mol Graph Model 2004; 22:221-30. [PMID: 14629980 DOI: 10.1016/j.jmgm.2003.08.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have performed molecular modeling studies on several sigma 1 specific ligands, including PD144418, spipethiane, haloperidol, pentazocine, and others to develop a pharmacophore for sigma 1 receptor-ligand binding, under the assumption that all the compounds interact at the same receptor binding site. The modeling studies have investigated the conformational and electrostatic properties of the ligands. Superposition of active molecules gave the coordinates of the hypothetical 5-point sigma 1 pharmacophore, as follows: R1 (0.85, 7.26, 0.30); R2 (5.47, 2.40, -1.51); R3 (-2.57, 4.82, -7.10); N (-0.71, 3.29, -6.40); carbon centroid (3.16, 4.83, -0.60), where R1, R2 were constructed onto the aromatic ring of each compound to represent hydrophobic interactions with the receptor; and R3 represents a hydrogen bond between the nitrogen atom and the receptor. Additional analyses were used to describe secondary binding sites to electronegative groups such as oxygen or sulfur atom. Those coordinates are (2.34, 5.08, -4.18). The model was verified by fitting other sigma 1 receptor ligands. This model may be used to search conformational databases for other possibly active ligands. In conjunction with rational drug design techniques the model may be useful in design and synthesis of novel sigma 1 ligands of high selectivity and potency. Calculations were performed using Sybyl 6.5.
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Affiliation(s)
- Tamara M Gund
- Department of Chemistry, Chemical Engineering and Environmental Science, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA.
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Gannon CJ, Malone DL, Napolitano LM. Reduction of IL-10 and nitric oxide synthesis by SR31747A (sigma ligand) in RAW murine macrophages. Surg Infect (Larchmt) 2003; 2:267-72; discussion 273. [PMID: 12593702 DOI: 10.1089/10962960152813304] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND There are several subtypes of sigma receptor, one of which is found throughout the immune system. SR31747A is a unique sigma ligand that possesses potent immune modulatory properties. Previous in vivo studies have documented that administration of SR31747A in murine models of sepsis resulted in decreased proinflammatory (IL-1, IL-6, TNF-alpha) and increased anti-inflammatory (IL-10) response (serum, splenocyte). Studies regarding the effect of this sigma ligand on purified macrophages are lacking. We therefore sought to investigate the effect of SR31747A in LPS-stimulated murine macrophages (RAW 264.7). METHODS RAW cells were incubated at 2.5 x 10(5) cells/well; controls were incubated with media alone, experimental groups contained LPS (0.01 microg) and SR31747A (1 nM, 10 nM, 100 nM, 1 microM, 10 microM). Supernatant and cells were harvested at 24 and 48 h. Concentrations of nitric oxide (Greiss reaction) and IL-10 were determined in the supernatant; cellular IL-10 mRNA was assessed. RESULTS SR31747A induced a dose-dependent reduction in NO and IL-10 protein release in LPS-stimulated murine macrophages. The decrease in IL-10 protein synthesis was paralleled by a significant dose-dependent reduction in IL-10 mRNA. CONCLUSION SR31747A is a novel immunomodulator that down regulates nitric oxide and IL-10 protein and mRNA expression. This in vitro reduction of IL-10 protein and mRNA expression is in contrast to previous in vivo murine studies. These data suggest that peripheral macrophages are not the source of the increased anti-inflammatory (IL-10) response induced by SR31747A.
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Affiliation(s)
- C J Gannon
- Department of Surgery, University of Maryland School of Medicine, 10 North Greene Street, Baltimore, MD 21201, USA
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Berthois Y, Bourrié B, Galiègue S, Vidal H, Carayon P, Martin PM, Casellas P. SR31747A is a sigma receptor ligand exhibiting antitumoural activity both in vitro and in vivo. Br J Cancer 2003; 88:438-46. [PMID: 12569389 PMCID: PMC2747535 DOI: 10.1038/sj.bjc.6600709] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
SR31747A is a recently described sigma receptor ligand that binds SR31747A-binding protein 1 (SR-BP) and emopamil-binding protein (EBP) (also called the sigma 1 receptor and the human sterol isomerase (HSI), respectively), and has immunoregulatory and antiproliferative activities. To further investigate its antitumour activity and focusing on cancers, which are sensitive to the molecule, we measured the proliferation of different human epithelial breast or prostate cancer cell lines following in vitro and in vivo SR31747A treatment. Firstly, in vitro, we found that nanomolar concentrations of SR31747A dramatically inhibited cell proliferation in both hormono-responsive and -unresponsive cancer cell lines. Secondly, tumour development was significantly decreased in mice treated with SR31747A. In an attempt to decipher the SR31747A mode of action, we found that the two binding sites may not fully account for this activity. Indeed, while competitive experiments indicated that EBP prevails in mediating SR31747A antiproliferative activity, an analysis of the expression of both receptors indicated that the cellular sensitivity to SR31747A is not correlated with either EBP or SR-BP expression. These data suggest that additional binding sites may exist. Preliminary binding studies demonstrated that SR31747A also binds to sigma 2, a protein that has not yet been cloned, but which is considered as a potential marker of the proliferative status of tumour cells. Altogether, our data demonstrate the antitumoural activity of SR31747A both in vitro and in vivo in two different cancer models, broaden the spectrum of its binding proteins and enhance the potential for further therapeutic development of the molecule.
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Affiliation(s)
- Y Berthois
- Laboratoire de cancérologie expérimentale EA2671, IFR Jean Roche, Faculté de Médecine Secteur Nord, Boulevard Pierre Dramard, 13916 Marseille cedex 20, France
| | - B Bourrié
- Département Immunologie-Oncologie, Sanofi Synthelabo, 371 rue du Professeur Joseph Blayac, 34184 Montpellier cedex 04, France
| | - S Galiègue
- Département Immunologie-Oncologie, Sanofi Synthelabo, 371 rue du Professeur Joseph Blayac, 34184 Montpellier cedex 04, France
| | - H Vidal
- Département Immunologie-Oncologie, Sanofi Synthelabo, 371 rue du Professeur Joseph Blayac, 34184 Montpellier cedex 04, France
| | - P Carayon
- Département Immunologie-Oncologie, Sanofi Synthelabo, 371 rue du Professeur Joseph Blayac, 34184 Montpellier cedex 04, France
| | - P M Martin
- Laboratoire de cancérologie expérimentale EA2671, IFR Jean Roche, Faculté de Médecine Secteur Nord, Boulevard Pierre Dramard, 13916 Marseille cedex 20, France
| | - P Casellas
- Département Immunologie-Oncologie, Sanofi Synthelabo, 371 rue du Professeur Joseph Blayac, 34184 Montpellier cedex 04, France
- Sanofi-Synthelabo Recherche, 371 rue du Professor Joseph Blayac, 34184 Montpellier cedex 04, France. E-mail:
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Ferrini JB, Jbilo O, Peleraux A, Combes T, Vidal H, Galiegue S, Casellas P. Transcriptomic classification of antitumor agents: application to the analysis of the antitumoral effect of SR31747A. Gene Expr 2003; 11:125-39. [PMID: 14686786 PMCID: PMC5991160 DOI: 10.3727/000000003108749026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2003] [Indexed: 11/24/2022]
Abstract
SR31747A is a sigma ligand that exhibits a potent antitumoral activity on various human tumor cell lines both in vitro and in vivo. To understand its mode of action, we used DNA microarray technology combined with a new bioinformatic approach to identify genes that are modulated by SR31747A in different human breast or prostate cancer cell lines. The SR31747A transcriptional signature was also compared with that of seven different representative anticancer drugs commonly used in the clinic. To this aim, we performed a two-dimensional hierarchical clustering analysis of drugs and genes which showed that 1) standard molecules with similar mechanism of action clustered together and 2) SR31747A does not belong to any previously characterized class of standard anticancer drugs. Moreover, we showed that 3) SR31747A mainly exerted its antiproliferative effect by inhibiting the expression of genes playing a key role in DNA replication and cell cycle progression. Finally, contrasting with other drugs, we obtained evidence that 4) SR31747A strongly inhibited the expression of three key enzymes of the nucleotide synthesis pathway (i.e., dihydrofolate reductase, thymidylate synthase, and thymidine kinase) with the latter shown both at the mRNA and protein levels. These results, obtained through a novel molecular approach to characterize and compare anticancer agents, showed that SR31747A exhibits an original mechanism of action, very likely through unexpected targets whose modulations may account for its antitumoral effect.
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Affiliation(s)
- Jean-Bernard Ferrini
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Omar Jbilo
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Annick Peleraux
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Therese Combes
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Hubert Vidal
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Sylvaine Galiegue
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
| | - Pierre Casellas
- Immunology-Oncology Department, Sanofi˜Synthelabo Recherche, 371 rue Prof. Blayac, F-34184 Montpellier CEDEX 04, France
- Address correspondence to Pierre Casellas, Sanofi-Synthelabo Recherche, 371 rue du Professeur Joseph Blayac, F-34184 Montpellier cedex 04, France. Tel: (33) 4 67 10 62 90; Fax: (33) 4 67 10 60 00; E-mail:
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37
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Ola MS, Moore P, Maddox D, El-Sherbeny A, Huang W, Roon P, Agarwal N, Ganapathy V, Smith SB. Analysis of sigma receptor (sigmaR1) expression in retinal ganglion cells cultured under hyperglycemic conditions and in diabetic mice. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 107:97-107. [PMID: 12425939 PMCID: PMC3773709 DOI: 10.1016/s0169-328x(02)00444-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The type 1 sigma receptor (sigmaR1) is a nonopiate and nonphencyclidine binding site that has numerous pharmacological and physiological functions. In some studies, agonists for sigmaR1 have been shown to afford neuroprotection against overstimulation of the NMDA receptor. sigmaR1 expression has been demonstrated recently in retinal ganglion cells (RGC). RGCs undergo apoptosis early in diabetic retinopathy via NMDA receptor overstimulation. In the present study we asked whether RGCs cultured under hyperglycemic conditions and RGCs of diabetic mice continue to express sigmaR1. RGCs were cultured 48 h in RPMI medium containing either 45 mM glucose or 11 mM glucose plus 34 mM mannitol (osmolar control). C57BL/6 mice were made diabetic using streptozotocin. The retina was dissected from normal and streptozotocin-induced diabetic mice 3, 6 and 12 weeks post-onset of diabetes. sigmaR1 was analyzed in cells using semiquantitative RT-PCR and in tissues by semiquantitative RT-PCR, in situ hybridization, Western blot analysis and immunolocalization. The RT-PCR analysis of cultured RGCs showed that sigmaR1 mRNA is expressed under hyperglycemic conditions at levels similar to control cells. Similarly, analysis of retinas of diabetic mice showed no difference in levels of mRNA encoding sigmaR1 compared to retinas of control mice. In situ hybridization analysis showed that expression patterns of sigmaR1 mRNA in the ganglion cell layer were similar between diabetic and control mice. Western blot analysis suggested that levels of sigmaR1 in retina were similar between diabetic and control retinas. Immunohistochemical analysis of sigmaR1 showed a similar pattern of sigmaR1 protein expression between control and diabetic retina. These studies demonstrate that sigmaR1 is expressed under hyperglycemic conditions in vitro and in vivo.
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MESH Headings
- Animals
- Blood Glucose/genetics
- Blotting, Western
- Cells, Cultured
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetic Retinopathy/drug therapy
- Diabetic Retinopathy/genetics
- Diabetic Retinopathy/metabolism
- Disease Models, Animal
- Gene Expression Regulation/physiology
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Nerve Degeneration/drug therapy
- Nerve Degeneration/physiopathology
- Nerve Degeneration/prevention & control
- Neuroprotective Agents/pharmacology
- RNA, Messenger/metabolism
- Rats
- Receptors, sigma/genetics
- Receptors, sigma/metabolism
- Retinal Ganglion Cells/cytology
- Retinal Ganglion Cells/metabolism
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Affiliation(s)
- M. Shamsul Ola
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
| | - Pamela Moore
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
| | - Dennis Maddox
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
| | - Amira El-Sherbeny
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
| | - Wei Huang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912
| | - Penny Roon
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
| | - Neeraj Agarwal
- Department of Anatomy and Cell Biology, University of North Texas Health Science Center, Fort Worth, TX 76107
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
- Department of Ophthalmology, Medical College of Georgia, Augusta, GA 30912
- Please send correspondence to: Sylvia B. Smith, Medical College of Georgia, Department of Cellular Biology and Anatomy, CB 2820, Augusta, GA 30912-2000, phone: (706) 721-7392, fax: (706) 721-6839,
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Abstract
B-ring hydroxylation is a major metabolic pathway for cholesterols and some steroids. In liver, 7 alpha-hydroxylation of cholesterols, mediated by CYP7A and CYP39A1, is the rate-limiting step of bile acid synthesis and metabolic elimination. In brain and other tissues, both sterols and some steroids including dehydroepiandrosterone (DHEA) are prominently 7 alpha-hydroxylated by CYP7B. The function of extra-hepatic steroid and sterol 7-hydroxylation is unknown. Nevertheless, 7-oxygenated cholesterols are potent regulators of cell proliferation and apoptosis; 7-oxygenated derivatives of DHEA, pregnenolone, and androstenediol can have major effects in the brain and in the immune system. The receptor targets involved remain obscure. It is argued that B-ring modification predated steroid evolution: non-enzymatic oxidation of membrane sterols primarily results in 7-oxygenation. Such molecules may have provided early growth and stress signals; a relic may be found in hydroxylation at the symmetrical 11-position of glucocorticoids. Early receptor targets probably included intracellular sterol sites, some modern steroids may continue to act at these targets. 7-Hydroxylation of DHEA may reflect conservation of an early signaling pathway.
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Affiliation(s)
- Richard Lathe
- Division of Biomedical Sciences, University of Edinburgh, George Square, EH9 9XD, Edinburgh, UK.
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Maurice T, Martin-Fardon R, Romieu P, Matsumoto RR. Sigma(1) (sigma(1)) receptor antagonists represent a new strategy against cocaine addiction and toxicity. Neurosci Biobehav Rev 2002; 26:499-527. [PMID: 12204195 DOI: 10.1016/s0149-7634(02)00017-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Cocaine is a highly addictive substance abused worldwide. Its mechanism of action involves initially inhibition of neuronal monoamine transporters in precise brain structures and primarily the dopamine reuptake system located on mesolimbic neurons. Cocaine rapidly increases the dopaminergic neurotransmission and triggers adaptive changes in numerous neuronal circuits underlying reinforcement, reward, sensitization and the high addictive potential of cocaine. Current therapeutic strategies focus on counteracting the cocaine effects directly on the dopamine transporter, through post-synaptic D(1), D(2) or D(3) receptors or through the glutamatergic, serotoninergic, opioid or corticotropin-releasing hormone systems. However, cocaine administration also results in the activation of numerous particular targets. Among them, the sigma(1) (sigma(1)) receptor is involved in several acute or chronic effects of cocaine. The present review will first bring concise overviews of the present strategies followed to alleviate cocaine addiction and animal models developed to analyze the pharmacology of cocaine addiction. Evidence involving activation of the sigma(1) receptor in the different aspects of cocaine abuse, will then be detailed, following acute, repeated, or overdose administration. The therapeutic potentials and neuropharmacological perspectives opened by the use of selective sigma(1) receptor antagonists in cocaine addiction will finally be discussed.
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Affiliation(s)
- Tangui Maurice
- CNRS UMR 5102, University of Montpellier II, c.c. 090, place Eugène Bataillon, 34095 Montpellier cedex 5, France.
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Cinato E, Péléraux A, Silve S, Galiègue S, Dhers C, Picard C, Jbilo O, Loison G, Casellas P. A DNA microarray-based approach to elucidate the effects of the immunosuppressant SR31747A on gene expression in Saccharomyces cerevisiae. Gene Expr 2002; 10:213-30. [PMID: 12450214 PMCID: PMC5977520 DOI: 10.3727/000000002783992370] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2002] [Indexed: 11/24/2022]
Abstract
SR31747A is an immunosuppressive agent that arrests cell proliferation in the yeast Saccharomyces cerevisiae. In this microorganism, SR31747A was shown to inhibit the ERG2 gene product, namely the delta8-delta7 sterol isomerase, involved in the ergosterol biosynthesis pathway. Although previous genetic experiments pointed to this enzyme as the target for SR31747A in yeast, the existence of other potential targets could not be ruled out. To enlighten this issue, we undertook a DNA microarray-based approach in which the expression profile of SR31747A-treated wild-type cells defining the "drug signature" was compared with the "mutant signature," the expression profile of the corresponding ERG2-deleted strain. We observed that treatment of ERG2-positive cells with SR31747A resulted in the modulation of mRNA levels of numerous genes. Among them, 121 werealso affected in untreated ERG2-disrupted cells compared with wild-type cells. By contrast, drug exposure did not induce any significant transcriptional change in the ERG2 null mutant. These results were consistent with SR31747A being an inhibitor of the sterol isomerase and demonstrated the absence of any additional SR31747A target. The detailed analysis of the observed 121 modulated genes provides new insights into the cellular response to ergosterol deprivation induced by SR31747A through inhibition of the ERG2 gene product.
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Affiliation(s)
- Elisa Cinato
- *Immunology-Oncology Department, Sanofi-Synthelabo, F-34184 Montpellier cedex 04, France
| | - Annick Péléraux
- *Immunology-Oncology Department, Sanofi-Synthelabo, F-34184 Montpellier cedex 04, France
| | - Sandra Silve
- †Molecular and Functional Genomics Department, Sanofi-Synthelabo, F-31676 Labège Innopole cedex, France
| | - Sylvaine Galiègue
- *Immunology-Oncology Department, Sanofi-Synthelabo, F-34184 Montpellier cedex 04, France
| | - Christiane Dhers
- ‡Analytical Research Department, Sanofi-Synthelabo, F-31036 Toulouse cedex, France
| | - Claudine Picard
- ‡Analytical Research Department, Sanofi-Synthelabo, F-31036 Toulouse cedex, France
| | - Omar Jbilo
- *Immunology-Oncology Department, Sanofi-Synthelabo, F-34184 Montpellier cedex 04, France
| | - Gérard Loison
- †Molecular and Functional Genomics Department, Sanofi-Synthelabo, F-31676 Labège Innopole cedex, France
| | - Pierre Casellas
- *Immunology-Oncology Department, Sanofi-Synthelabo, F-34184 Montpellier cedex 04, France
- Address correspondence to Pierre Casellas, Sanofi-Synthelabo, 371 rue du Professeur Joseph Blayac, F-34184 Montpellier cedex 04, France. Tel: (33) 4 67 10 62 90; Fax: (33) 4 67 10 60 00; E-mail:
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Maurice T, Phan VL, Urani A, Guillemain I. Differential involvement of the sigma(1) (sigma(1)) receptor in the anti-amnesic effect of neuroactive steroids, as demonstrated using an in vivo antisense strategy in the mouse. Br J Pharmacol 2001; 134:1731-41. [PMID: 11739250 PMCID: PMC1572889 DOI: 10.1038/sj.bjp.0704355] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2001] [Revised: 08/30/2001] [Accepted: 08/30/2001] [Indexed: 11/08/2022] Open
Abstract
1. The sigma(1) (sigma(1)) receptor cDNA was cloned in several animal species. Molecular tools are now available to identify its endogenous effectors, such as neuroactive steroids, and to establish its precise physiological role. In particular, the sigma(1) receptor is involved in memory processes, as observed in pharmacological and pathological rodent models of amnesia. 2. In order to establish the involvement of sigma(1) receptors in memory, a 16-mer oligodeoxynucleotide antisense to the sigma(1) receptor cDNA (aODN), and its mismatched control (mODN) were prepared and centrally administered into the mouse brain. The anti-amnesic effects induced by the selective sigma(1) agonist PRE-084 and the steroid dehydroepiandrosterone (DHEA) sulphate or pregnenolone sulphate were examined in ODN-treated animals. 3. The aODN treatment failed to affect the dissociation constant (K(d)) but significantly decreased the number of sigma(1) sites (B(max)) labelled with [(3)H]-(+)-SKF-10,047 in the hippocampus and cortex. In these structures, the in vivo binding levels were also diminished, according to the dose and number of injections, as compared with control animals injected with saline or mODN. 4. Cannulation and injections failed to affect the open-field behaviour of the animals. However, the anti-amnesic effects of PRE-084 and DHEA sulphate against the dizocilpine-induced impairments were blocked after aODN treatment in the short- and long-term memory tests. The anti-amnesic effects of pregnenolone sulphate remained unchanged. 5. These observations bring a molecular basis to the modulatory role of sigma(1) receptors in memory, and reveal that the anti-amnesic action of neuroactive steroids may not similarly involve an interaction with sigma(1) receptors.
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Affiliation(s)
- T Maurice
- INSERM U. 336, Behavioural Neuropharmacology group, Institut de Biologie, 4, Blvd Henri IV, 34060 Montpellier, France.
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Ola MS, Moore P, El-Sherbeny A, Roon P, Agarwal N, Sarthy VP, Casellas P, Ganapathy V, Smith SB. Expression pattern of sigma receptor 1 mRNA and protein in mammalian retina. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 95:86-95. [PMID: 11687279 PMCID: PMC3742362 DOI: 10.1016/s0169-328x(01)00249-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Sigma receptors are nonopiate and nonphencyclidine binding sites that are thought to be neuroprotective due to modulation of N-methyl-D-aspartate (NMDA) receptors. Sigma receptor 1 expression has been demonstrated in numerous tissues including brain. Recently, studies using binding assays have demonstrated sigma receptor 1 in neural retina, however these studies did not demonstrate in which retinal cell type(s) sigma receptor 1 was present nor did they establish unequivocally the molecular identity of the receptor. The present study was designed to address these issues. Reverse transcription-polymerase chain reaction (RT-PCR) analysis amplified sigma receptor 1 in neural retina, RPE-choroid complex, and lens isolated from mice. A similar RT-PCR product was amplified also in three cultured cell lines, rat Müller cells, rat ganglion cells and human ARPE-19 cells. In situ hybridization analysis revealed abundant sigma receptor 1 expression in ganglion cells, cells of the inner nuclear layer, inner segments of photoreceptor cells and retinal pigment epithelial (RPE) cells. Immunohistochemical studies detected the sigma receptor 1 protein in retinal ganglion, photoreceptor, RPE cells and surrounding the soma of cells in the inner nuclear layer. These data provide the first cellular localization of sigma receptor 1 in neural retina and establish the molecular identity of sigma receptor 1 in retinal cells. The demonstration that sigma receptor 1 is present in ganglion cells is particularly noteworthy given the well-documented susceptibility of these cells to glutamate toxicity. Our findings suggest that retinal ganglion cells may be amenable to the neuroprotective effects of sigma ligands under conditions of neurotoxicity such as occurs in diabetes.
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Affiliation(s)
- M. Shamsul Ola
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta, GA 30912
| | - Pamela Moore
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta, GA 30912
| | - Amira El-Sherbeny
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta, GA 30912
| | - Penny Roon
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta, GA 30912
| | - Neeraj Agarwal
- Department of Anatomy and Cell Biology University of North Texas Health Science Center, Fort Worth, TX 76107
| | - Vijay P. Sarthy
- Dept of Ophthalmology Northwestern University Medical School, Chicago, IL 60611
| | | | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology Medical College of Georgia, Augusta, GA 30912
| | - Sylvia B. Smith
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta, GA 30912
- Department of Ophthalmology Medical College of Georgia, Augusta, GA 30912
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43
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Maurice T, Urani A, Phan VL, Romieu P. The interaction between neuroactive steroids and the sigma1 receptor function: behavioral consequences and therapeutic opportunities. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 37:116-32. [PMID: 11744080 DOI: 10.1016/s0165-0173(01)00112-6] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Steroids, synthesized in peripheral glands or centrally in the brain--the latter being named neurosteroids--exert an important role as modulators of the neuronal activity by interacting with different receptors or ion channels. In addition to the modulation of GABA(A), NMDA or cholinergic receptors, neuroactive steroids interact with an atypical intracellular receptor, the sigma(1) protein. This receptor has been cloned in several species, and highly selective synthetic ligands are available. At the cellular level, sigma1 agonists modulate intracellular calcium mobilization and extracellular calcium influx, NMDA-mediated responses, acetylcholine release, and alter monoaminergic systems. At the behavioral level, the sigma1 receptor is involved in learning and memory processes, the response to stress, depression, neuroprotection and pharmacodependence. Pregnenolone, dehydroepiandrosterone, and their sulfate esters behave as sigma1 agonists, while progesterone is a potent antagonist. This review will detail the physiopathological consequences of these interactions, focusing on recent results on memory and depression. The therapeutical interest of selective sigma1 receptor agonists in alleviating aging-related cognitive deficits will be discussed.
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Affiliation(s)
- T Maurice
- Behavioural Neuropharmacology Group, INSERM U. 336, Institut de Biologie, 4 Bvd Henri IV, 34060, Montpellier, France.
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Seth P, Ganapathy ME, Conway SJ, Bridges CD, Smith SB, Casellas P, Ganapathy V. Expression pattern of the type 1 sigma receptor in the brain and identity of critical anionic amino acid residues in the ligand-binding domain of the receptor. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1540:59-67. [PMID: 11476895 DOI: 10.1016/s0167-4889(01)00117-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The type 1 sigma receptor (sigmaR1) has been shown to participate in a variety of functions in the central nervous system. To identify the specific regions of the brain that are involved in sigmaR1 function, we analyzed the expression pattern of the receptor mRNA in the mouse brain by in situ hybridization. SigmaR1 mRNA was detectable primarily in the cerebral cortex, hippocampus, and Purkinje cells of cerebellum. To identify the critical anionic amino acid residues in the ligand-binding domain of sigmaR1, we employed two different approaches: chemical modification of anionic amino acid residues and site-directed mutagenesis. Chemical modification of anionic amino acids in sigmaR1 with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reduced the ligand-binding activity markedly. Since it is known that a splice variant of this receptor which lacks exon 3 does not have the ability to bind sigma ligands, the ligand-binding domain with its critical anionic amino acid residues is likely to be present in or around the region coded by exon 3. Therefore, each of the anionic amino acids in this region was mutated individually and the influence of each mutation on ligand binding was assessed. These studies have identified two anionic amino acids, D126 and E172, that are obligatory for ligand binding. Even though the ligand-binding function was abolished by these two mutations, the expression of these mutants was normal at the protein level. These results show that sigmaR1 is expressed at high levels in specific areas of the brain that are involved in memory, emotion and motor functions. The results also provide important information on the chemical nature of the ligand-binding site of sigmaR1 that may be of use in the design of sigmaR1-specific ligands with potential for modulation of sigmaR1-related brain functions.
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Affiliation(s)
- P Seth
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912, USA
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45
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Abstract
Sigma (sigma) receptors have been implicated in psychosis, cognition, neuroprotection, and locomotion in the central nervous system. The signal transduction mechanisms for sigma receptors have not been fully elucidated. In this study, we examined the possible coupling between sigma(1) receptors and heterotrimeric guanine nucleotide-binding proteins (G proteins) in rodent brain. In sigma(1) receptor-rich cerebellar membrane preparations, the competitive binding curves of two sigma(1) agonists, (+)pentazocine and 1S,2R-(-)-cis-N-[2-(3, 4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)cyclohexylamine (BD737), were unaffected by the addition of 10 microM guanosine-5'-O-(gamma-thio)-triphosphate (GTPgammaS). Neither (+)pentazocine (1-100 microM) nor BD737 (0.01-10 microM) stimulated GTPase activities significantly above basal levels in agonist-stimulated GTPase activity assays in cerebellar membranes. Furthermore, when using the method of agonist-stimulated [35S]GTPgammaS binding as assessed by autoradiography, we did not observe significant stimulation of [35S]GTPgammaS binding in rat brain sections by either (+)pentazocine or BD737. The above results demonstrate that the sigma(1) receptor is not likely be directly coupled to G proteins.
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Affiliation(s)
- W Hong
- Neuroscience Program, The George Washington University Medical Center, Washington, DC 20037, USA
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46
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Lupardus PJ, Wilke RA, Aydar E, Palmer CP, Chen Y, Ruoho AE, Jackson MB. Membrane-delimited coupling between sigma receptors and K+ channels in rat neurohypophysial terminals requires neither G-protein nor ATP. J Physiol 2000; 526 Pt 3:527-39. [PMID: 10922005 PMCID: PMC2270035 DOI: 10.1111/j.1469-7793.2000.00527.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Receptor-mediated modulation of ion channels generally involves G-proteins, phosphorylation, or both in combination. The sigma receptor, which modulates voltage-gated K+ channels, is a novel protein with no homology to other receptors known to modulate ion channels. In the present study patch clamp and photolabelling techniques were used to investigate the mechanism by which sigma receptors modulate K+ channels in peptidergic nerve terminals. The sigma receptor photoprobe iodoazidococaine labelled a protein with the same molecular mass (26 kDa) as the sigma receptor protein identified by cloning. The sigma receptor ligands pentazocine and SKF10047 modulated K+ channels, despite intra-terminal perfusion with GTP-free solutions, a G-protein inhibitor (GDPbetaS), a G-protein activator (GTPgammaS) or a non-hydrolysable ATP analogue (AMPPcP). Channels in excised outside-out patches were modulated by ligand, indicating that soluble cytoplasmic factors are not required. In contrast, channels within cell-attached patches were not modulated by ligand outside a patch, indicating that receptors and channels must be in close proximity for functional interactions. Channels expressed in oocytes without receptors were unresponsive to sigma receptor agonists, ruling out inhibition through a direct drug interaction with channels. These experiments indicate that sigma receptor-mediated signal transduction is membrane delimited, and requires neither G-protein activation nor protein phosphorylation. This novel transduction mechanism is mediated by membrane proteins in close proximity, possibly through direct interactions between the receptor and channel. This would allow for more rapid signal transduction than other ion channel modulation mechanisms, which in the present case of neurohypophysial nerve terminals would lead to the enhancement of neuropeptide release.
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Affiliation(s)
- P J Lupardus
- Departments of Physiology, Medicine, Molecular Biology and Pharmacology, University of Wisconsin School of Medicine, 1300 University Avenue, Madison, WI 53706, USA
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Simony-Lafontaine J, Esslimani M, Bribes E, Gourgou S, Lequeux N, Lavail R, Grenier J, Kramar A, Casellas P. Immunocytochemical assessment of sigma-1 receptor and human sterol isomerase in breast cancer and their relationship with a series of prognostic factors. Br J Cancer 2000; 82:1958-66. [PMID: 10864204 PMCID: PMC2363255 DOI: 10.1054/bjoc.2000.1162] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/1999] [Accepted: 01/17/2000] [Indexed: 11/18/2022] Open
Abstract
The purpose of this study was to immunocytochemically investigate two new markers, the sigma-1 receptor and the human sterol isomerase (hSI), in comparison with a series of clinicopathological and immunocytochemical prognostic factors in a trial including 95 patients with operable primary breast cancers. Our results showed no statistically significant relationship between these two markers and the age of the patients, their menopausal status, the tumour size and its histological grade, the nodal status and the expression of the Ki-67 proliferative marker. However, we evidenced a close correlation between the sigma-1 receptor expression and the hormonal receptor positivity (P = 0.008), essentially due to a link with the progesterone receptor status (P = 0.01). By contrast there was an inverse relationship between hSI expression and the oestrogen receptor and/or progesterone receptor positivity (P = 0.098). A significant relationship was shown between both the sigma-1 receptor, hSI expressions and Bcl2 expression, with P= 0.017 and 0.035 respectively. We also assessed whether the expression of the sigma-1 receptor or hSI might be linked with disease-free survival (DFS) and found that the presence of hSI and the absence of sigma-1 receptor expression were associated with a poorer disease-free survival (P= 0.007). Altogether these results suggest that in primary breast carcinomas in association with the evaluation of the steroid receptor status, the sigma-1 receptor and hSI may be interesting new markers useful to identify those patients who might be able to benefit from an adjuvant therapy.
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48
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Soustre I, Dupuy PH, Silve S, Karst F, Loison G. Sterol metabolism and ERG2 gene regulation in the yeast Saccharomyces cerevisiae. FEBS Lett 2000; 470:102-6. [PMID: 10734216 DOI: 10.1016/s0014-5793(00)01300-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Certain exogenously-supplied sterols, like ergost-8-enol, are efficiently converted into ergosterol in yeast. We have taken advantage of this property to study the regulation of the Delta8-Delta7-sterol isomerase-encoding ERG2 gene in an ergosterol auxotrophic mutant devoid of squalene-synthase activity. Ergosterol starvation leads to an 8-16-fold increase in ERG2 gene expression. Such an increase was also observed in wild-type cells either grown anaerobically or treated with SR31747A a sterol isomerase inhibitor. Exogenously-supplied zymosterol is entirely transformed into ergosterol, which represses ERG2 transcription. By contrast, exogenously-supplied ergosterol has little or no effect on ERG2 transcription.
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MESH Headings
- Anaerobiosis
- Biological Transport
- Cholesterol/metabolism
- Cholesterol/pharmacology
- Cyclohexanes/pharmacology
- Ergosterol/analogs & derivatives
- Ergosterol/biosynthesis
- Ergosterol/metabolism
- Ergosterol/pharmacology
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Fungal/drug effects
- Genes, Fungal/genetics
- Genes, Fungal/physiology
- Genes, Reporter/genetics
- Lanosterol/metabolism
- Lanosterol/pharmacology
- Morpholines/pharmacology
- Mutation/genetics
- Oxygen/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Saccharomyces cerevisiae/drug effects
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Steroid Isomerases/antagonists & inhibitors
- Steroid Isomerases/genetics
- Sterols/metabolism
- Sterols/pharmacology
- Transcription, Genetic/drug effects
- Transcription, Genetic/genetics
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Affiliation(s)
- I Soustre
- Université Louis Pasteur, INRA, 28, rue de Herrlisheim, P.O. Box 507, 68021, Colmar, France
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49
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Abstract
Several recent advances are leading to a better understanding of sigma receptors. Here we focus on our recent findings regarding cellular functions of sigma-2 receptors and discuss their possible clinical implications. Agonists at sigma-2 receptors induced changes in cell morphology and apoptosis in various cell types. Sigma-2 receptor activation produced both transient and sustained increases in [Ca++]i, derived from different intracellular stores. These changes in [Ca++]i and cytotoxic effects are mediated by intracellular sigma-2 receptors. Sigma-2 agonists induced apoptosis in drug-resistant cancer cells, enhanced the potency of DNA damaging agents, and down-regulated expression of p-glycoprotein mRNA. Thus, sigma-2 receptor agonists may be useful in treatment of drug-resistant cancers. Sigma radioligands have been used in tumor imaging. We also discuss how sigma-2 antagonists might prevent the irreversible motor side effects of typical neuroleptics. Sigma-2 receptors may subserve a novel signalling pathway to apoptosis, involved in regulation of cell proliferation and/or viability.
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Affiliation(s)
- W D Bowen
- Unit on Receptor Biochemistry and Pharmacology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0815, USA.
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50
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Soriani O, Le Foll F, Galas L, Roman F, Vaudry H, Cazin L. The sigma-ligand (+)-pentazocine depresses M current and enhances calcium conductances in frog melanotrophs. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E73-80. [PMID: 10409130 DOI: 10.1152/ajpendo.1999.277.1.e73] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gramicidin-perforated patch clamp experiments and microfluorimetric measurements were performed to study the ionic mechanisms involved in the sigma-receptor-mediated stimulation of frog (Rana ridibunda) pituitary melanotrophs. The sigma-ligand (+)-pentazocine (50 microM) depressed a sustained outward K(+) current. The kinetic properties of this K(+) component, investigated by analyzing tail currents, were reminiscent of those of the M current (I(M)), with an activation threshold close to -60 mV, a -21-mV half-maximal activation potential, and two-component exponential deactivation kinetics at -90 mV. (+)-Pentazocine (20 microM) produced a 12-mV rightward shift of the activation curve and accelerated the deactivation rate of the tail current. It is also demonstrated that (+)-pentazocine (20 microM) reversibly increased both voltage-dependent calcium conductances and internal calcium level. Altogether, these results suggest that the sigma-receptor-induced modulation of I(M) and calcium currents likely underlies the increase of intracellular [Ca(2+)].
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Affiliation(s)
- O Soriani
- European Institute for Peptide Research, Laboratory of Cellular and Molecular Neuroendocrinology, Institut National de la Santé et de la Recherche Médicale U413, Institut Fédératif de Recherche Multidisciplinaire sur les Peptides no. 23, France
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