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Spicer MM, Weber MA, Luo Z, Yang J, Narayanan NS, Fisher RA. Regulator of G protein signaling 6 (RGS6) in dopamine neurons promotes EtOH seeking, behavioral reward, and susceptibility to relapse. Psychopharmacology (Berl) 2024:10.1007/s00213-024-06631-8. [PMID: 38856764 DOI: 10.1007/s00213-024-06631-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 05/31/2024] [Indexed: 06/11/2024]
Abstract
Mesolimbic dopamine (DA) transmission is believed to play a critical role in mediating reward responses to drugs of abuse, including alcohol (EtOH). The neurobiological mechanisms underlying EtOH-seeking behavior and dependence are not fully understood, and abstinence remains the only effective way to prevent alcohol use disorders (AUDs). Here, we developed novel RGS6fl/fl; DAT-iCreER mice to determine the role of RGS6 in DA neurons on EtOH consumption, reward, and relapse behaviors. We found that RGS6 is expressed in DA neurons in both human and mouse ventral tegmental area (VTA), and that RGS6 loss in mice upregulates DA transporter (DAT) expression in VTA DA neuron synaptic terminals. Remarkably, loss of RGS6 in DA neurons significantly reduced EtOH consumption, preference, and reward in a manner indistinguishable from that seen in RGS6-/- mice. Strikingly, RGS6 loss from DA neurons before or after EtOH behavioral reward is established significantly reduced (~ 50%) re-instatement of reward following extinguishment, demonstrating distinct roles of RGS6 in promoting reward and relapse susceptibility to EtOH. These studies identify DA neurons as the locus of RGS6 action in promoting EtOH consumption, preference, reward, and relapse. RGS6 is unique among R7 RGS proteins in promoting rather than suppressing behavioral responses to drugs of abuse and to modulate EtOH behavioral reward. This is a result of RGS6's pre-synaptic actions that we hypothesize promote VTA DA transmission by suppressing GPCR-Gαi/o-DAT signaling in VTA DA neurons. These studies identify RGS6 as a potential therapeutic target for behavioral reward and relapse to EtOH.
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Affiliation(s)
- Mackenzie M Spicer
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, 51 Newton Rd. BSB 2-512, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, 169 Newton Rd., Iowa City, IA, 52242, USA
- Department of Neurology, University of Iowa Carver College of Medicine, 200 Hawkins Dr., Iowa City, IA, 52242, USA
| | - Matthew A Weber
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, 169 Newton Rd., Iowa City, IA, 52242, USA
- Department of Neurology, University of Iowa Carver College of Medicine, 200 Hawkins Dr., Iowa City, IA, 52242, USA
| | - Zili Luo
- Department of Pediatrics, University of Iowa Carver College of Medicine, 200 Hawkins Dr., Iowa City, IA, 52242, USA
| | - Jianqi Yang
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, 51 Newton Rd. BSB 2-512, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, 169 Newton Rd., Iowa City, IA, 52242, USA
| | - Nandakumar S Narayanan
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, 169 Newton Rd., Iowa City, IA, 52242, USA
- Department of Neurology, University of Iowa Carver College of Medicine, 200 Hawkins Dr., Iowa City, IA, 52242, USA
| | - Rory A Fisher
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, 51 Newton Rd. BSB 2-512, Iowa City, IA, 52242, USA.
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, 169 Newton Rd., Iowa City, IA, 52242, USA.
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Ahlers-Dannen KE, Yang J, Spicer MM, Fu D, DeVore A, Fisher RA. A splice acceptor variant in RGS6 associated with intellectual disability, microcephaly, and cataracts disproportionately promotes expression of a subset of RGS6 isoforms. J Hum Genet 2024; 69:145-152. [PMID: 38332109 DOI: 10.1038/s10038-024-01220-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/11/2024] [Accepted: 01/18/2024] [Indexed: 02/10/2024]
Abstract
Intellectual disability (ID) is associated with an increased risk of developing psychiatric disorders, suggesting a common underlying genetic factor. Importantly, altered signaling and/or expression of regulator of G protein signaling 6 (RGS6) is associated with ID and numerous psychiatric disorders. RGS6 is highly conserved and undergoes complex alternative mRNA splicing producing ~36 protein isoforms with high sequence similarity historically necessitating a global approach in functional studies. However, our recent analysis in mice revealed RGS6 is most highly expressed in CNS with RGS6L(+GGL) isoforms predominating. A previously reported genetic variant in intron 17 of RGS6 (c.1369-1G>C), associated with ID, may provide further clues into RGS6L(+GGL) isoform functional delineation. This variant was predicted to alter a highly conserved canonical 3' acceptor site creating an alternative branch point within exon 18 (included in a subset of RGS6L(+GGL) transcripts) and a frameshift forming an early stop codon. We previously identified this alternative splice site and demonstrated its use generates RGS6Lζ(+GGL) isoforms. Here, we show that the c.1369-1G>C variant disrupts the canonical, preferred (>90%) intron 17 splice site and leads to the exclusive use of the alternate exon 18 splice site, inducing disproportionate expression of a subset of isoforms, particularly RGS6Lζ(+GGL). Furthermore, RGS6 global knockout mice do not exhibit ID. Thus, ID caused by the c.1369-1G>C variant likely results from altered RGS6 isoform expression, rather than RGS6 isoform loss. In summary, these studies highlight the importance of proper RGS6 splicing and identify a previously unrecognized role of G protein signaling in ID.
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Affiliation(s)
- K E Ahlers-Dannen
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - J Yang
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - M M Spicer
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - D Fu
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - A DeVore
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - R A Fisher
- Department of Neuroscience and Pharmacology, The Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
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Spicer MM, Weber MA, Luo Z, Yang J, Narayanan NS, Fisher RA. Regulator of G protein signaling 6 (RGS6) in ventral tegmental area (VTA) dopamine neurons promotes EtOH seeking, behavioral reward and susceptibility to relapse. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563844. [PMID: 37961154 PMCID: PMC10634791 DOI: 10.1101/2023.10.24.563844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Mesolimbic dopamine (DA) transmission is believed to play a critical role in mediating reward responses to drugs of abuse, including alcohol (EtOH). EtOH is the most abused substance worldwide with chronic consumption often leading to the development of dependence and abuse. Unfortunately, the neurobiological mechanisms underlying EtOH-seeking behavior and dependence are not fully understood, and abstinence remains the only effective way to prevent alcohol use disorders (AUDs). Here, we developed novel RGS6 fl/fl ; DAT-iCreER mice to determine the role of RGS6 in VTA DA neurons on EtOH consumption and reward behaviors. We found that RGS6 is expressed in DA neurons in both human and mouse VTA, and that RGS6 loss in mice upregulates DA transporter (DAT) expression in VTA DA neuron synaptic terminals. Remarkably, loss of RGS6 in VTA DA neurons significantly reduced EtOH consumption, preference, and reward in a manner indistinguishable from that seen in RGS6 -/- mice. Strikingly, RGS6 loss from VTA DA neurons before or after EtOH behavioral reward is established significantly reduced (∼50%) re-instatement of reward following extinguishment, demonstrating distinct roles of RGS6 in promoting reward and relapse susceptibility to EtOH. These studies illuminate a critical role of RGS6 in the mesolimbic circuit in promoting EtOH seeking, reward, and reinstatement. We propose that RGS6 functions to promote DA transmission through its function as a negative modulator of GPCR-Gα i/o -DAT signaling in VTA DA neurons. These studies identify RGS6 as a potential therapeutic target for behavioral reward and relapse to EtOH.
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