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Yadav N, Thelma BK. Deletion induced splicing in RIC3 drives nicotinic acetylcholine receptor regulation with implications for endoplasmic reticulum stress in human astrocytes. Glia 2023; 71:1217-1232. [PMID: 36602087 DOI: 10.1002/glia.24333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/25/2022] [Accepted: 12/22/2022] [Indexed: 01/06/2023]
Abstract
Nicotinic acetylcholine receptor (nAChR) dysregulation in astrocytes is reported in neurodegenerative disorders. Modulation of nAChRs through agonists confers protection to astrocytes from stress but regulation of chaperones involved in proteostasis with pathological implications is unclear. Resistance to inhibitors of cholinesterase 3 (RIC3), a potential chaperone of nAChRs is poorly studied in humans. We characterized RIC3 in astrocytes derived from an isogenic wild-type and Cas9 edited "del" human iPSC line harboring a 25 bp homozygous deletion in exon2. Altered RIC3 transcript ratio due to deletion induced splicing and an unexpected gain of α7nAChR expression were observed in "del" astrocytes. Transcriptome analysis showed higher expression of neurotransmitter/G-protein coupled receptors mediated by cAMP and calcium/calmodulin-dependent kinase signaling with increased cytokines/glutamate secretion. Functional implications examined using tunicamycin induced ER stress in wild-type astrocyte stress model showed cell cycle arrest, RIC3 upregulation, reduction in α7nAChR membrane levels but increased α4nAChR membrane expression. Conversely, tunicamycin-treated "del" astrocytes showed a comparatively higher α4nAChR membrane expression and upsurged cAMP signaling. Furthermore, reduced expression of stress markers CHOP, phospho-PERK and lowered XBP1 splicing in western blot and qPCR, validated by proteome-based pathway analysis indicated lowered disease severity. Findings indicate (i) a complex RNA regulatory mechanism via exonic deletion induced splicing; (ii) RIC-3 as a disordered protein having contrasting effects on co-expressed nAChR subtypes under basal/stress conditions; and (iii) RIC3 as a potential drug target against ER stress in astrocytes for neurodegenerative/nicotine-related brain disorders. Cellular rescue mechanism through deletion induced exon skipping may encourage ASO-based therapies for tauopathies.
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Affiliation(s)
- Navneesh Yadav
- Department of Genetics, University of Delhi South Campus, New Delhi, India
| | - B K Thelma
- Department of Genetics, University of Delhi South Campus, New Delhi, India
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2
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Speculation on How RIC-3 and Other Chaperones Facilitate α7 Nicotinic Receptor Folding and Assembly. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27144527. [PMID: 35889400 PMCID: PMC9318448 DOI: 10.3390/molecules27144527] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 11/17/2022]
Abstract
The process of how multimeric transmembrane proteins fold and assemble in the endoplasmic reticulum is not well understood. The alpha7 nicotinic receptor (α7 nAChR) is a good model for multimeric protein assembly since it has at least two independent and specialized chaperones: Resistance to Inhibitors of Cholinesterase 3 (RIC-3) and Nicotinic Acetylcholine Receptor Regulator (NACHO). Recent cryo-EM and NMR data revealed structural features of α7 nAChRs. A ser-ala-pro (SAP) motif precedes a structurally important but unique "latch" helix in α7 nAChRs. A sampling of α7 sequences suggests the SAP motif is conserved from C. elegans to humans, but the latch sequence is only conserved in vertebrates. How RIC-3 and NACHO facilitate receptor subunits folding into their final pentameric configuration is not known. The artificial intelligence program AlphaFold2 recently predicted structures for NACHO and RIC-3. NACHO is highly conserved in sequence and structure across species, but RIC-3 is not. This review ponders how different intrinsically disordered RIC-3 isoforms from C. elegans to humans interact with α7 nAChR subunits despite having little sequence homology across RIC-3 species. Two models from the literature about how RIC-3 assists α7 nAChR assembly are evaluated considering recent structural information about the receptor and its chaperones.
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Kawamura K, Maruyama IN. Mutation in histone deacetylase HDA-3 leads to shortened locomotor healthspan in Caenorhabditis elegans. Aging (Albany NY) 2020; 12:23525-23547. [PMID: 33276344 PMCID: PMC7762513 DOI: 10.18632/aging.202296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022]
Abstract
Some genes are essential for survival, while other genes play modulatory roles on health and survival. Genes that play modulatory roles may promote an organism’s survival and health by fine-tuning physiological processes. An unbiased search for genes that alter an organism’s ability to maintain aspects of health may uncover modulators of lifespan and healthspan. From an unbiased screen for Caenorhabditis elegans mutants that show a progressive decline in motility, we aimed to identify genes that play a modulatory role in maintenance of locomotor healthspan. Here we report the involvement of hda-3, encoding a class I histone deacetylase, as a genetic factor that contributes in the maintenance of general health and locomotion in C. elegans. We identified a missense mutation in HDA-3 as the causative mutation in one of the isolated strains that show a progressive decline in maximum velocity and travel distance. From transcriptome analysis, we found a cluster of genes on Chromosome II carrying BATH domains that were downregulated by hda-3. Furthermore, downregulation of individual bath genes leads to significant decline in motility. Our study identifies genetic factors that modulate the maintenance of locomotor healthspan and may reveal potential targets for delaying age-related locomotor decline.
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Affiliation(s)
- Kazuto Kawamura
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
| | - Ichiro N Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
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Treinin M, Jin Y. Cholinergic transmission in C. elegans: Functions, diversity, and maturation of ACh-activated ion channels. J Neurochem 2020; 158:1274-1291. [PMID: 32869293 DOI: 10.1111/jnc.15164] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/13/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023]
Abstract
Acetylcholine is an abundant neurotransmitter in all animals. Effects of acetylcholine are excitatory, inhibitory, or modulatory depending on the receptor and cell type. Research using the nematode C. elegans has made ground-breaking contributions to the mechanistic understanding of cholinergic transmission. Powerful genetic screens for behavioral mutants or for responses to pharmacological reagents identified the core cellular machinery for synaptic transmission. Pharmacological reagents that perturb acetylcholine-mediated processes led to the discovery and also uncovered the composition and regulators of acetylcholine-activated channels and receptors. From a combination of electrophysiological and molecular cellular studies, we have gained a profound understanding of cholinergic signaling at the levels of synapses, neural circuits, and animal behaviors. This review will begin with a historical overview, then cover in-depth current knowledge on acetylcholine-activated ionotropic receptors, mechanisms regulating their functional expression and their functions in regulating locomotion.
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Affiliation(s)
- Millet Treinin
- Department of Medical Neurobiology, Hadassah Medical school - Hebrew University, Jerusalem, Israel
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
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Safdie G, Liewald JF, Kagan S, Battat E, Gottschalk A, Treinin M. RIC-3 phosphorylation enables dual regulation of excitation and inhibition of Caenorhabditis elegans muscle. Mol Biol Cell 2016; 27:2994-3003. [PMID: 27489343 PMCID: PMC5042584 DOI: 10.1091/mbc.e16-05-0265] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 07/26/2016] [Indexed: 01/25/2023] Open
Abstract
Excitation–inhibition balance is essential for normal brain function. Calcineurin-dependent dephosphorylation of RIC-3, a chaperone of nicotinic acetylcholine receptors, disinhibits GABAA receptors, enabling fine-tuning of excitation–inhibition balance. Brain function depends on a delicate balance between excitation and inhibition. Similarly, Caenorhabditis elegans motor system function depends on a precise balance between excitation and inhibition, as C. elegans muscles receive both inhibitory, GABAergic and excitatory, cholinergic inputs from motor neurons. Here we show that phosphorylation of the ER-resident chaperone of nicotinic acetylcholine receptors, RIC-3, leads to increased muscle excitability. RIC-3 phosphorylation at Ser-164 depends on opposing functions of the phosphatase calcineurin (TAX-6), and of the casein kinase II homologue KIN-10. Effects of calcineurin down-regulation and of phosphorylated RIC-3 on muscle excitability are mediated by GABAA receptor inhibition. Thus RIC-3 phosphorylation enables effects of this chaperone on GABAA receptors in addition to nAChRs. This dual effect provides coordinated regulation of excitation and inhibition and enables fine-tuning of the excitation–inhibition balance. Moreover, regulation of inhibitory GABAA signaling by calcineurin, a calcium- and calmodulin-dependent phosphatase, enables homeostatic balancing of excitation and inhibition.
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Affiliation(s)
- Gracia Safdie
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jana F Liewald
- Buchmann Institute for Molecular Life Sciences and Institute of Biochemistry, Goethe-University, D-60438 Frankfurt, Germany
| | - Sarah Kagan
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Emil Battat
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences and Institute of Biochemistry, Goethe-University, D-60438 Frankfurt, Germany
| | - Millet Treinin
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Sadigh-Eteghad S, Majdi A, Mahmoudi J, Golzari SEJ, Talebi M. Astrocytic and microglial nicotinic acetylcholine receptors: an overlooked issue in Alzheimer's disease. J Neural Transm (Vienna) 2016; 123:1359-1367. [PMID: 27262818 DOI: 10.1007/s00702-016-1580-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/27/2016] [Indexed: 02/01/2023]
Abstract
It is increasingly recognized that astrocytes and microglia-associated dysfunction contribute to AD pathology. In addition, glial nicotinic acetylcholine receptors (nAChRs) play a role in AD-related phenomena, such as neuron survival, synaptic plasticity, and memory. From mechanistic point of view, the glial regulation of pro-inflammatory cytokines, as common contributors in AD, is modulated by nAChRs. Astrocytic and microglial nAChRs contribute to Aβ metabolism, including Aβ phagocytosis and degradation as well as Aβ-related oxidative stress and neurotoxicity. These receptors are also involved in neurotransmission and gliotransmission through indirect interaction with N-Methyl-D-aspartate (NMDA) and a-amino-3-hydroxy-5-methyl-4 isoxazolepropionic acid (AMPA) receptors as well as gamma-aminobutyric acid (GABA) and intracellular calcium regulation. In addition, glial nAChRs participate in trophic factors-induced neuroprotection. This review gathers the most recent advances along with the previous data on astrocytic and microglial nAChRs role in AD pathogenesis.
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Affiliation(s)
- Saeed Sadigh-Eteghad
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Alireza Majdi
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Javad Mahmoudi
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran
| | - Samad E J Golzari
- Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahnaz Talebi
- Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran
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Ben-David Y, Mizrachi T, Kagan S, Krisher T, Cohen E, Brenner T, Treinin M. RIC-3 expression and splicing regulate nAChR functional expression. Mol Brain 2016; 9:47. [PMID: 27129882 PMCID: PMC4850696 DOI: 10.1186/s13041-016-0231-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/22/2016] [Indexed: 11/11/2022] Open
Abstract
Background The nicotinic acetylcholine receptors form a large and diverse family of acetylcholine gated ion channels having diverse roles in the central nervous system. Maturation of nicotinic acetylcholine receptors is a complex and inefficient process requiring assistance from multiple cellular factors including RIC-3, a functionally conserved endoplasmic reticulum-resident protein and nicotinic acetylcholine receptor-specific chaperone. In mammals and in Drosophila melanogaster RIC-3 is alternatively spliced to produce multiple isoforms. Results We used electrophysiological analysis in Xenopus laevis oocytes, in situ hybridization, and quantitative real-time polymerase chain reaction assays to investigate regulation of RIC-3’s expression and splicing and its effects on the expression of three major neuronal nicotinic acetylcholine receptors. We found that RIC-3 expression level and splicing affect nicotinic acetylcholine receptor functional expression and that two conserved RIC-3 isoforms express in the brain differentially. Moreover, in immune cells RIC-3 expression and splicing are regulated by inflammatory signals. Conclusions Regulation of expression level and splicing of RIC-3 in brain and in immune cells following inflammation enables regulation of nicotinic acetylcholine receptor functional expression. Specifically, in immune cells such regulation via effects on α7 nicotinic acetylcholine receptor, known to function in the cholinergic anti-inflammatory pathway, may have a role in neuroinflammatory diseases. Electronic supplementary material The online version of this article (doi:10.1186/s13041-016-0231-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yael Ben-David
- Department of Medical Neurobiology, Faculty of Medicine, The Hebrew University, Ein Kerem, P.O. Box 12271, Jerusalem, 91120, Israel
| | - Tehila Mizrachi
- Department of Neurology, Hadassah Medical Center, Jerusalem, Israel
| | - Sarah Kagan
- Department of Medical Neurobiology, Faculty of Medicine, The Hebrew University, Ein Kerem, P.O. Box 12271, Jerusalem, 91120, Israel
| | - Tamar Krisher
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The Hebrew University, Jerusalem, Israel
| | - Emiliano Cohen
- Department of Medical Neurobiology, Faculty of Medicine, The Hebrew University, Ein Kerem, P.O. Box 12271, Jerusalem, 91120, Israel
| | - Talma Brenner
- Department of Neurology, Hadassah Medical Center, Jerusalem, Israel
| | - Millet Treinin
- Department of Medical Neurobiology, Faculty of Medicine, The Hebrew University, Ein Kerem, P.O. Box 12271, Jerusalem, 91120, Israel.
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Regulation of nicotinic acetylcholine receptors in Alzheimer׳s disease: a possible role of chaperones. Eur J Pharmacol 2015; 755:34-41. [PMID: 25771456 DOI: 10.1016/j.ejphar.2015.02.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/15/2015] [Accepted: 02/22/2015] [Indexed: 12/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) seem to play an integral role in the progress and/or prevention of Alzheimer׳s diseases (AD). Functional abnormalities and problems in biogenesis and trafficking of nAChRs are two major culprits in AD; on the other hand, chaperones modulate post-translational changes in nAChRs. Moreover, they indirectly regulate nAChRs by controlling AD-related proteins such as tau and amyloid beta (Aβ). In this review, we go through recent studies which are showing that chaperones modulate the expression of nAChRs in a subtype-specific manner and explain how AD progress is affected by nAChRs chaperoning.
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Smith MA, Zhang Y, Polli JR, Wu H, Zhang B, Xiao P, Farwell MA, Pan X. Impacts of chronic low-level nicotine exposure on Caenorhabditis elegans reproduction: identification of novel gene targets. Reprod Toxicol 2013; 40:69-75. [PMID: 23735997 DOI: 10.1016/j.reprotox.2013.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/25/2013] [Accepted: 05/24/2013] [Indexed: 12/17/2022]
Abstract
Effects and mechanisms of chronic exposure to low levels of nicotine is an area fundamentally important however less investigated. We employed the model organism Caenorhabditis elegans to investigate potential impacts of chronic (24h) and low nicotine exposure (6.17-194.5 μM) on stimulus-response, reproduction, and gene expressions. Nicotine significantly affects the organism's response to touch stimulus (p=0.031), which follows a dose-dependent pattern. Chronic nicotine exposure promotes early egg-laying events and slightly increased egg productions during the first 72 h of adulthood. The expressions of 10 (egl-10, egl-44, hlh-14, ric-3, unc-103, unc-50, unc-68, sod-1, oxi-1, and old-1) out of 18 selected genes were affected significantly. Other tested genes were cat-4, egl-19, egl-47, egl-5, lin-39, unc-43, pink-1, and age-1. Changes in gene expression were more evident at low dosages than at relatively high levels. Genes implicated in reproduction, cholinergic signaling, and stress response were regulated by nicotine, suggesting widespread physiological impacts of nicotine.
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Affiliation(s)
- Michael A Smith
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
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10
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Holden-Dye L, Joyner M, O'Connor V, Walker RJ. Nicotinic acetylcholine receptors: a comparison of the nAChRs of Caenorhabditis elegans and parasitic nematodes. Parasitol Int 2013; 62:606-15. [PMID: 23500392 DOI: 10.1016/j.parint.2013.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/28/2013] [Accepted: 03/05/2013] [Indexed: 01/15/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a key role in the normal physiology of nematodes and provide an established target site for anthelmintics. The free-living nematode, Caenorhabditis elegans, has a large number of nAChR subunit genes in its genome and so provides an experimental model for testing novel anthelmintics which act at these sites. However, many parasitic nematodes lack specific genes present in C. elegans, and so care is required in extrapolating from studies using C. elegans to the situation in other nematodes. In this review the properties of C. elegans nAChRs are reviewed and compared to those of parasitic nematodes. This forms the basis for a discussion of the possible subunit composition of nAChRs from different species of parasitic nematodes. Currently our knowledge on this is largely based on studies using heterologous expression and pharmacological analysis of receptor subunits in Xenopus laevis oocytes. It is concluded that more information is required regarding the subunit composition and pharmacology of endogenous nAChRs in parasitic nematodes.
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Affiliation(s)
- Lindy Holden-Dye
- Centre for Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, UK.
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11
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Koperniak TM, Garg BK, Boltax J, Loring RH. Cell-specific effects on surface α7 nicotinic receptor expression revealed by over-expression and knockdown of rat RIC3 protein. J Neurochem 2013; 124:300-9. [PMID: 23157401 DOI: 10.1111/jnc.12095] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/14/2012] [Accepted: 10/02/2012] [Indexed: 12/01/2022]
Abstract
We tested whether surface α7 nicotinic acetylcholine receptor expression is dependent on an endogenous chaperone named Resistance to Inhibitors of Cholinesterase 3 (RIC3) by comparing RIC3 protein in rat GH4C1 and human SH-EP1 cells, which express strikingly different surface receptor levels following α7 transfection. Cloned rat RIC3 exists in at least two isoforms because of an ambiguous splice site between exons 4 and 5. Both rat isoforms permit surface α7 expression in SH-EP1 and human embryonic kidney (HEK) cells measured by α-bungarotoxin binding. Contrary to expectations, endogenous RIC3 protein expression determined by immunoblots did not differ between untransfected GH4C1 or SH-EP1 cells. siRNA against rat RIC3 exon 4 and shRNA against exons 2, 5 and 6 knocked down transfected rat RIC3 expression in SH-EP1 cells and simultaneously blocked toxin binding. However, no RNAi construct blocked binding when co-transfected with α7 into GH4C1 cells. shRNA against rat exons 2 and 5 knocked down rat RIC3 protein transfected into GH4C1 cells with a time course suggesting a protein half-life of a few days. These results suggest GH4C1 cells may possess unknown chaperone(s) allowing high surface α7 expression in the absence of known RIC3 splice variants.
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Affiliation(s)
- Thomas M Koperniak
- Department of Pharmaceutical Science, Northeastern University, Boston, MA 02115, USA
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12
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Bennett HM, Lees K, Harper KM, Jones AK, Sattelle DB, Wonnacott S, Wolstenholme AJ. Xenopus laevis RIC-3 enhances the functional expression of the C. elegans homomeric nicotinic receptor, ACR-16, in Xenopus oocytes. J Neurochem 2012; 123:911-8. [PMID: 22970690 PMCID: PMC3549563 DOI: 10.1111/jnc.12013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 08/23/2012] [Accepted: 09/10/2012] [Indexed: 01/25/2023]
Abstract
RIC-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nAChRs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and Xenopus laevis oocytes. Maximal activity of RIC-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. We cloned the X. laevis ric-3 cDNA and tested the frog protein in oocyte expression studies. X. laevis RIC-3 shares 52% amino acid identity with human RIC-3 and only 17% with that of Caenorhabditis elegans. We used the C. elegans nicotinic receptor, ACR-16, to compare the ability of RIC-3 from three species to enhance receptor expression. In the absence of RIC-3, the proportion of oocytes expressing detectable nAChRs was greatly reduced. Varying the ratio of acr-16 to X. laevis ric-3 cRNAs injected into oocytes had little impact on the total cell current. When X. laevis, human or C. elegans ric-3 cRNAs were co-injected with acr-16 cRNA (1 : 1 ratio), 100 μM acetylcholine induced larger currents in oocytes expressing X. laevis RIC-3 compared with its orthologues. This provides further evidence for a species-specific component of RIC-3 activity, and suggests that X. laevis RIC-3 is useful for enhancing the expression of invertebrate nAChRs in X. laevis oocytes.
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Affiliation(s)
- Hayley M Bennett
- Department of Infectious Diseases and Center for Tropical & Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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Zhang Y, Chen D, Ennis AC, Polli JR, Xiao P, Zhang B, Stellwag EJ, Overton A, Pan X. Chemical dispersant potentiates crude oil impacts on growth, reproduction, and gene expression in Caenorhabditis elegans. Arch Toxicol 2012; 87:371-82. [PMID: 22990136 DOI: 10.1007/s00204-012-0936-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/28/2012] [Indexed: 01/09/2023]
Abstract
The economic, environmental, and human health impacts of the deepwater horizon (DWH) oil spill have been of significant concern in the general public and among scientists. This study employs parallel experiments to test the effects of crude oil from the DWH oil well, chemical dispersant Corexit 9500A, and dispersant-oil mixture on growth and reproduction in the model organism Caenorhabditis elegans. Both the crude oil and the dispersant significantly inhibited the reproduction of C. elegans. Dose-dependent inhibitions of hatched larvae production were observed in worms exposed to both crude oil and dispersant. Importantly, the chemical dispersant Corexit 9500A potentiated crude oil effects; dispersant-oil mixture induced more significant effects than oil or dispersant-alone exposures. While oil-alone exposure and dispersant-alone exposure have none to moderate inhibitory effects on hatched larvae production, respectively, the mixture of dispersant and oil induced much more significant inhibition of offspring production. The production of hatched larvae was almost completely inhibited by several high concentrations of the dispersant-oil mixture. This suggests a sensitive bioassay for future investigation of oil/dispersant impacts on organisms. We also investigated the effects of crude oil/dispersant exposure at the molecular level by measuring the expressions of 31 functional genes. Results showed that the dispersant and the dispersant-oil mixture induced aberrant expressions of 12 protein-coding genes (cat-4, trxr-2, sdhb-1, lev-8, lin-39, unc-115, prdx-3, sod-1, acr-16, ric-3, unc-68, and acr-8). These 12 genes are associated with a variety of biological processes, including egg-laying, oxidative stress, muscle contraction, and neurological functions. In summary, the toxicity potentiating effect of chemical dispersant must be taken into consideration in future crude oil cleanup applications.
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Affiliation(s)
- Yanqiong Zhang
- Department of Biology, East Carolina University, N108 Howell Science Complex, Greenville, NC 27858, USA
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Chaperoning α7 neuronal nicotinic acetylcholine receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:718-29. [PMID: 22040696 DOI: 10.1016/j.bbamem.2011.10.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 09/25/2011] [Accepted: 10/17/2011] [Indexed: 11/22/2022]
Abstract
The α7 subtype of nicotinic acetylcholine receptors (AChRs) is one of the most abundant members of the Cys-loop family of receptors present in the central nervous system. It participates in various physiological processes and has received much attention as a potential therapeutic target for a variety of pathologies. The importance of understanding the mechanisms controlling AChR assembly and cell-surface delivery lies in the fact that these two processes are key to determining the functional pool of receptors actively engaged in synaptic transmission. Here we review recent studies showing that RIC-3, a protein originally identified in the worm Caenorhabditis elegans, modulates the expression of α7 AChRs in a subtype-specific manner. Potentiation of AChR expression by post-transcriptional events is also critically assessed.
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Ric-3 promotes alpha7 nicotinic receptor assembly and trafficking through the ER subcompartment of dendrites. J Neurosci 2010; 30:10112-26. [PMID: 20668195 DOI: 10.1523/jneurosci.6344-09.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The function of Ric-3, which is required for nicotinic acetylcholine receptor (nAChR) expression in C. elegans, is unclear. Here we found that Ric-3 can promote or inhibit cell-surface delivery of alpha-bungarotoxin-binding nAChRs (BgtRs) composed of alpha7 subunits. At low levels, Ric-3 promoted BgtR assembly, endoplasmic reticulum (ER) release, and cell-surface delivery without trafficking from the ER. At high Ric-3 levels, Ric-3 suppressed BgtR surface delivery, but not its assembly, and BgtRs were retained in the ER or in Ric-3-containing aggregates. In PC12 cells, native BgtRs trafficked to the cell surface from the ER where low levels of endogenous Ric-3 were observed. In cultured neurons, native Ric-3 levels were higher than in PC12 cells, and Ric-3 and alpha7 subunits were found in somata and dendrites, but not axons, of inhibitory interneurons. Ric-3 trafficked with alpha7 subunits in rapidly moving vesicles to dendrites, where it was restricted to the ER subcompartment. We conclude that Ric-3 has two potential functions. At low levels, Ric-3 interactions are short-lived and promote BgtR assembly and ER release. At higher levels, Ric-3 interactions are longer-lived and mediate ER retention. In neurons, Ric-3 ER retention appears to promote transport within the dendritic ER subcompartment, thereby restricting alpha7 trafficking to dendrites and preventing axonal transport.
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Walstab J, Hammer C, Lasitschka F, Möller D, Connolly CN, Rappold G, Brüss M, Bönisch H, Niesler B. RIC-3 exclusively enhances the surface expression of human homomeric 5-hydroxytryptamine type 3A (5-HT3A) receptors despite direct interactions with 5-HT3A, -C, -D, and -E subunits. J Biol Chem 2010; 285:26956-26965. [PMID: 20522555 PMCID: PMC2930695 DOI: 10.1074/jbc.m110.122838] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although five 5-hydroxytryptamine type 3 (5-HT3) subunits (A-E) have been cloned, knowledge on the regulation of their assembly is limited. RIC-3 has been identified as a chaperone specific for the pentameric ligand-gated nicotinic acetylcholine and 5-HT(3) receptors. Therefore, we examined the impact of RIC-3 on differently composed 5-HT(3) receptors with the focus on 5-HT3C, -D, and -E subunits. The influence of RIC-3 on these receptor subtypes is supported by the presence of RIC3 mRNA in tissues expressing at least one of the subunits 5-HT3C, -D, and -E. Furthermore, immunocytochemical studies on transfected mammalian cells revealed co-localization in the endoplasmic reticulum and direct interaction of RIC-3 with 5-HT3A, -C, -D, and -E. Functional and pharmacological characterization was performed using HEK293 cells expressing 5-HT3A or 5-HT3A + 5-HT3B (or -C, -D, or -E) in the presence or absence of RIC-3. Ca(2+) influx analyses revealed that RIC-3 does not influence the 5-HT concentration-response relationship on 5-HT(3)A receptors but leads to differential increases of 5-HT-induced maximum response (E(max)) on cells expressing different subunits. Increases of E(max) were due to analogously enhanced B(max) values for binding of the 5-HT(3) receptor antagonist [(3)H]GR65630. The observed enhanced cell surface expression of the tested 5-HT3 subunit combinations correlated with the increased surface expression of 5-HT3A as determined by flow cytometry. In conclusion, we showed that RIC-3 can interact with 5-HT3A, -C, -D, and -E subunits and predominantly enhances the surface expression of homomeric 5-HT(3)A receptors in HEK293 cells. These data implicate a possible role of RIC-3 in determining 5-HT(3) receptor composition in vivo.
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Affiliation(s)
- Jutta Walstab
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany; Institute of Pharmacology and Toxicology, University of Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Christian Hammer
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Felix Lasitschka
- Institute of Pathology, University of Heidelberg, Im Neuenheimer Feld 220/221, 69120 Heidelberg, Germany
| | - Dorothee Möller
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Christopher N Connolly
- Centre for Neuroscience, Division of Medical Sciences, Ninewells Medical School, University of Dundee, Dundee DD1 9SY, Scotland, United Kingdom
| | - Gudrun Rappold
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Michael Brüss
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Heinz Bönisch
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Beate Niesler
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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