Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response.
- Authors
- Munoz, Michaelanne B; Slesinger, Paul A
- Year
- 2014
- Journal
- Neuron
- PMID
- 24811384
- DOI
- 10.1016/j.neuron.2014.03.011
- PMCID
- PMC4141045
The subcellular pathways that regulate G protein-gated inwardly rectifying potassium (GIRK or Kir3) channels are important for controlling the excitability of neurons. Sorting nexin 27 (SNX27) is a PDZ-containing protein known to bind GIRK2c/GIRK3 channels, but its function in vivo is poorly understood. Here, we investigated the role of SNX27 in regulating GIRK currents in dopamine (DA) neurons of the ventral tegmental area (VTA). Mice lacking SNX27 in DA neurons exhibited reduced GABABR-activated GIRK currents but had normal Ih currents and DA D2R-activated GIRK currents. Expression of GIRK2a, an SNX27-insensitive splice variant, restored GABABR-activated GIRK currents in SNX27-deficient DA neurons. Remarkably, mice with significantly reduced GABABR-activated GIRK currents in only DA neurons were hypersensitive to cocaine and could be restored to a normal locomotor response with GIRK2a expression. These results identify a pathway for regulating excitability of VTA DA neurons, highlighting SNX27 as a promising target for treating addiction.
Viability of mice with targeted disruption of SNX27 expression in VTA DA neurons(A) Schematic shows conditional deletion of exon 3 in Snx27 occurs in DAT-expressing cells. Floxed animals with SNX27 exon 3 flanked by loxP sites were crossed to DAT-Cre+/− line. SNX27 exon 3 is excised by Cre in DAT-expressing dopamine neurons, referred to as SNX27DA KO mice. (B,C) Dual immunofluorescence for SNX27 (red) and TH (green) in coronal sections from WT and SNX27DA KO. (D) Immunofluorescence for TH in coronal sections from WT and SNX27DA KO. No apparent difference in TH+ density (7.5± 0.99 for WT, n=2 and 6.0 ± 0.26 for KO, n=2 per 150µm2. (E) Resting membrane potentials were indistinguishable in DA neurons from WT, DAT-Cre+/− and SNX27DA KO mice. (F) Ih currents were indistinguishable in DA neurons from WT, Dat-Cre+/− and SNX27DA KO mice.
Reduced GABABR-GIRK currents in VTA DA neurons lacking SNX27 protein(A,C) Whole-cell recordings from VTA DA neurons show baclofen-activated GIRK currents (IBaclofen; 300 µM) from WT and SNX27DA KO mice. Extracellular Ba2+ (1 mM), a selective inhibitor of inwardly rectifying potassium channels (Kir), decreases IBaclofen. Outward current measured at −50 mV is plotted as a function of time. (B,D) Scatter plot of IBaclofen for indicated DA neurons. **p<0.01, one-way ANOVA with Bonferroni post hoc test.
Loss of GABABR-dependent inhibition of firing in DA neurons of SNX27DA KO mice(A) Current clamp recording shows action potentials in a wild-type DA neuron (200pA injection) before (ACSF) and after application of 300µM baclofen (+Baclofen, red trace). (B) Input-output plot shows firing frequency increases with larger current injections (solid circles, ACSF; n=16) and suppression with baclofen (open circles) (p<0.01 at 100–300pA, 2-way ANOVA with Bonferroni post hoc test). (C) Current clamp recording from DA neuron (200pA injection) before (ACSF) and after application of 300µM baclofen (+Baclofen, red trace). (D) Firing frequency is plotted as a function of current injection before (solid triangles, ACSF; n=24) and after baclofen (open triangles). Input-output plot shows loss of baclofen-dependent inhibition of firing at all current injection levels (n.s. all steps, 2-way ANOVA).
Attenuation of direct G protein-activation of GIRK channels in VTA DA neurons of SNX27DA KO mice(A,B) Outward currents recorded with 100µM GTPγS in the recording pipet from WT or SNX27DA KO DA neuron. A time-dependent increase in outward current occurs with GTPγS, which is inhibited by extracellular Ba2+, consistent with direct activation of GIRK channels (Logothetis et al., 1987). (C) Scatter plot shows Ba2+-sensitive activated currents. GTPγS-induced current is significantly reduced in SNX27DA KO neurons (**p<0.01, one-way ANOVA with Bonferroni post hoc test).
GABABR-GIRK currents and inhibition are restored with expression of SNX27b in VTA DA neurons of SNX27DA KO mice(A) Schematic shows stereotaxic injection of AAV DIO-Snx27b-ires-GFP into VTA of SNX27DA KO mice. Fluorescence and DIC images of eYFP/GFP+ cell selected for recording from ex vivo midbrain section of SNX27DA KO with either AAV DIO-eYFP or AAV DIO-Snx27b-ires-GFP (scale bar: 20 µm). (B) Top, whole-cell recordings from VTA DA neurons show baclofen-activated GIRK currents (IBaclofen; 300 µM) from WT and SNX27DA KO mice injected with AAV DIO-eYFP or AAV DIO-Snx27b-ires-GFP, and inhibition with Ba2+ (1 mM). Scale bar; 100 s and 50 pA. Bottom, baclofen-induced currents of Snx27b-ires-GFP positive cells are significantly larger compared to +eYFP (**p<0.01, Student’s t test). Scatter plot of IBaclofen for indicated DA neurons with average current indicated by solid black bar. (C,D) Input-output plots show firing frequency increase with larger current injections in the absence (solid circles, ACSF) and presence (filled circles) of baclofen for DA neurons infected with eYFP (C) (n=6) or SNX27-ires-GFP (D) (n=6) (p<0.01 absence versus presence baclofen, 160–300pA, 2-way ANOVA with Bonferroni post hoc test).
Expression of SNX27-insensitive GIRK2a in VTA DA neurons of SNX27DA KO mice restores GABABR-activated GIRK currents and inhibition(A) Schematic shows stereotaxic injection of AAV DIO-GIRK2a-eYFP into VTA of SNX27DA KO mice. Fluorescence and DIC images of eYFP positive cell selected for recording from ex vivo midbrain section of SNX27DA KO mice injected with AAV DIO-Girk2a-eYFP. (scale bar: 20 µm) (B) Top, whole-cell recordings from VTA DA neurons show baclofen-activated GIRK currents (IBaclofen; 300 µM) from WT and SNX27DA KO mice injected with AAV DIO-eYFP or AAV DIO-Girk2a-eYFP, and response to Ba2+ (1 mM). Scale bar is 100 s and 100 pA. Bottom, baclofen-induced currents in GIRK2a-eYFP positive cells are significantly increased from eYFP+ cells (**p<0.05, Student’s t test). Scatter plot of IBaclofen for indicated DA neurons with average current indicated by solid black bar. (C,D) Input-output plots show firing frequency increases as a function of larger current injections in the absence (solid circles, ACSF) and presence of baclofen for DA neurons cells infected with eYFP (n=6) (C) or GIRK2a-eYFP (n=8) (D). Baclofen inhibits firing activity in GIRK2a-eYFP expressing DA neurons (D) but not in eYFP expressing neurons (C) of SNX27DA KO mice (p<0.01 absence versus presence baclofen at 140–300pA, 2-way ANOVA with Bonferroni post hoc test).
Enhanced cocaine locomotor response in SNX27DA KO mice(A) Total distance traveled in novel open field environment by WT (n=18), DAT-Cre+/− (n=17), and SNX27DA KO (n=17) mice over 1 hour (**p<0.01 vs WT, p<0.05 vs DAT-Cre+/−, one-way ANOVA with Bonferroni post hoc test). (B) No significant change in thigmotaxis for SNX27DA KO mice (n=12) vs. WT (n=11) or vs. DAT-Cre+/− (n=11). Time spent in center of chamber (central 10” squared of 16” squared chamber, n.s. one-way ANOVA). (C) Heightened sensitivity to cocaine in SNX27DA KO mice. Locomotor activity measured in WT (n=6), DAT-Cre+/− (n=16) or SNX27DA KO (n=14) mice following a single injection (i.p.) of saline (0.9%) or cocaine (20mg/kg). (**p<0.05 cocaine vs. saline, two-way ANOVA with Bonferroni post hoc test). (D) Fold increase in locomotor activity with cocaine measured over 30 minute period. (**p<0.05, One-way ANOVA with Bonferroni post hoc test).
SNX27-insensitive GIRK2a expression in DA neurons of SNX27DA KO mice restores normal response to cocaine(A) Schematic shows stereotaxic injection of AAV DIO GIRK2a-eYFP or AAV DIO eYFP into VTA of SNX27DA KO mice. (B) Whole-cell recordings from VTA DA neurons show rescue of baclofen-activated GIRK currents (IBaclofen; 300 µM) in SNX27DA KO mice injected with AAV DIO-GIRK2a-eYFP. Scale bar is 100 s and 100 pA. (C) Locomotor activity plots show change in activity following a single cocaine injection (20 mg/kg) for a SNX27DA KO mouse expressing eYFP (left) or GIRK2a-eYFP (right). Starting and ending points indicated by blue and red circles, respectively. Note reduced activity in mouse expressing GIRK2a. (D) Bar graph shows fold-increase in locomotor activity with cocaine (20 mg/kg) for uninfected WT mice (n=5) and SNX27DA KO mice injected with either AAV DIO eYFP (n=3) or AAV DIO GIRK2a-eYFP (n=3) (**p<0.05 eYFP vs GIRK2a-eYFP, unpaired t-test).
| # | Section | Preview |
|---|---|---|
| 40 | Materials and Methods — Stereotaxic Surgery | Mice age P24–26 were anesthetized with ketamine/xylazine 10/100mg/kg i.p. and placed in a… |
| 41 | Materials and Methods — Virus Production | pAAV-EF1a-double floxed-EYFP-WPRE-HGH pA (Addgene plasmid 20296) was made into AAV serotype 5 at… |
| 42 | Materials and Methods — Open field test | All behavior experiments were conducted in the light phase from 1100–1500. Animals were brought… |
| 43 | Materials and Methods — Statistical analysis | Data were analyzed using Prism 5.0 software. One- or two-way ANOVA with Bonferroni post hoc test or… |
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| Direct modulation of G protein-gated inwardly rectifying potassium (GIRK) channels. | Nguyen H et al. | — | 2024 | → |
| Partial loss of Sorting Nexin 27 resembles age- and Down syndrome-associated T cell dysfunctions. | Rodriguez-Rodriguez C et al. | — | 2024 | → |
| SNX27: A trans-species cognitive modulator with implications for anxiety and stress susceptibility. | Armada G et al. | — | 2024 | → |
| A review of the genomics of neonatal abstinence syndrome. | Yen E et al. | — | 2023 | → |
| Polygenic risk scores and the need for pharmacotherapy in neonatal abstinence syndrome. | Bibi S et al. | — | 2023 | → |
| Endosomal Sorting Protein SNX27 and Its Emerging Roles in Human Cancers. | Deb S et al. | — | 2022 | → |
| GIRK3 deletion facilitates kappa opioid signaling in chondrocytes, delays vascularization and promotes bone lengthening in mice. | Taylor EL et al. | — | 2022 | → |
| An update on cellular and molecular determinants of Parkinson's disease with emphasis on the role of the retromer complex. | Macías-Calvio V et al. | — | 2021 | → |
| Cocaine self-administration induces sex-dependent protein expression in the nucleus accumbens. | López AJ et al. | — | 2021 | → |
| Comparison of K<sup>+</sup> Channel Families. | Taura J et al. | — | 2021 | → |
| Structural insights into GIRK2 channel modulation by cholesterol and PIP<sub>2</sub>. | Mathiharan YK et al. | — | 2021 | → |
| Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system. | Jeremic D et al. | — | 2021 | → |
| Toward Understanding the Molecular Role of SNX27/Retromer in Human Health and Disease. | Chandra M et al. | — | 2021 | → |
| Permeation mechanisms through the selectivity filter and the open helix bundle crossing gate of GIRK2. | Li DL et al. | — | 2020 | → |
| Sorting Nexin 27 as a potential target in G protein‑coupled receptor recycling for cancer therapy (Review). | Bao Z et al. | — | 2020 | → |
| Discovery and Characterization of VU0529331, a Synthetic Small-Molecule Activator of Homomeric G Protein-Gated, Inwardly Rectifying, Potassium (GIRK) Channels. | Kozek KA et al. | — | 2019 | → |
| GIRK Channel Activity in Dopamine Neurons of the Ventral Tegmental Area Bidirectionally Regulates Behavioral Sensitivity to Cocaine. | McCall NM et al. | — | 2019 | → |
| Distinct Roles for Two Chromosome 1 Loci in Ethanol Withdrawal, Consumption, and Conditioned Place Preference. | Kozell LB et al. | — | 2018 | → |
| GIRK currents in VTA dopamine neurons control the sensitivity of mice to cocaine-induced locomotor sensitization. | Rifkin RA et al. | — | 2018 | → |
| <i>Snx27</i> Deletion Promotes Recovery From Spinal Cord Injury by Neuroprotection and Reduces Macrophage/Microglia Proliferation. | Zeng Y et al. | — | 2018 | → |
| A KCNJ6 gene polymorphism modulates theta oscillations during reward processing. | Kamarajan C et al. | — | 2017 | → |
| GIRK2 splice variants and neuronal G protein-gated K<sup>+</sup> channels: implications for channel function and behavior. | Marron Fernandez de Velasco E et al. | — | 2017 | → |
| GPCR Signaling and Trafficking: The Long and Short of It. | Pavlos NJ et al. | — | 2017 | → |
| G Protein-Gated Potassium Channels: A Link to Drug Addiction. | Rifkin RA et al. | — | 2017 | → |
| Selective targeting of M-type potassium K<sub>v</sub> 7.4 channels demonstrates their key role in the regulation of dopaminergic neuronal excitability and depression-like behaviour. | Li L et al. | — | 2017 | → |
| Activation of GABAB2 subunits alleviates chronic cerebral hypoperfusion-induced anxiety-like behaviours: A role for BDNF signalling and Kir3 channels. | Lu Y et al. | — | 2016 | → |
| A Role for the GIRK3 Subunit in Methamphetamine-Induced Attenuation of GABAB Receptor-Activated GIRK Currents in VTA Dopamine Neurons. | Munoz MB et al. | — | 2016 | → |
| G Protein-Gated Inwardly Rectifying Potassium Channel Subunit 3 Knock-Out Mice Show Enhanced Ethanol Reward. | Tipps ME et al. | — | 2016 | → |
| SNX27, a protein involved in down syndrome, regulates GPR17 trafficking and oligodendrocyte differentiation. | Meraviglia V et al. | — | 2016 | → |
| Sorting nexin 27 interacts with Fzd7 and mediates Wnt signalling. | Sun L et al. | — | 2016 | → |
| A defect in the retromer accessory protein, SNX27, manifests by infantile myoclonic epilepsy and neurodegeneration. | Damseh N et al. | — | 2015 | → |
| Behavioral and Genetic Evidence for GIRK Channels in the CNS: Role in Physiology, Pathophysiology, and Drug Addiction. | Mayfield J et al. | — | 2015 | → |
| GIRK3 gates activation of the mesolimbic dopaminergic pathway by ethanol. | Herman MA et al. | — | 2015 | → |
| GIRK Channel Plasticity and Implications for Drug Addiction. | Marron Fernandez de Velasco E et al. | — | 2015 | → |
| GIRK Channels: A Potential Link Between Learning and Addiction. | Tipps ME et al. | — | 2015 | → |
| GIRK Channels Modulate Opioid-Induced Motor Activity in a Cell Type- and Subunit-Dependent Manner. | Kotecki L et al. | — | 2015 | → |
| Kir3 channels undergo arrestin-dependant internalization following delta opioid receptor activation. | Nagi K et al. | — | 2015 | → |
| Sorting nexin 27 regulates basal and stimulated brush border trafficking of NHE3. | Singh V et al. | — | 2015 | → |
| Time-Dependent Effects of Ethanol on BK Channel Expression and Trafficking in Hippocampal Neurons. | Palacio S et al. | — | 2015 | → |
| Sorting nexin 27 regulates Aβ production through modulating γ-secretase activity. | Wang X et al. | — | 2014 | → |