Phosphorylation state–dependent modulation of spinal glycine receptors alleviates inflammatory pain

Acuña, Mario A.; Yévenes, Gonzalo E.; Ralvenius, William T.; Benke, Dietmar; Lio, Alessandra; Lara, César O.; Muñoz, Braulio; Burgos, Carlos F.; Moraga-Cid, Gustavo; Corringer, Pierre‐Jean; Zeilhofer, Hanns Ulrich

doi:10.1172/jci83817

Cited by 50 publications

(78 citation statements)

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“…1A-C). The extent of inhibition was similar to what has previously been reported for dorsal horn neurons 22,25,27 . The application of PGE 2 did not affect the glycine-activated currents in the absence of EP2-R expression (−6.5 ± 3.4%, P = 0.48, paired t-test).…”

Section: Resultssupporting

confidence: 89%

“…Further experiments expressing α3GlyRs with a mutation in the consensus site for PKA-dependent phosphorylation (i.e. S346A) showed, in agreement with previous studies 22,27 , that the activation of bPAC did not significantly decrease the glycine-activated currents (−4.0 ± 8.8% from control, P = 0.67, paired t-test).…”

Section: Resultssupporting

confidence: 88%

“…We first assessed the effects of EP2-R activation on the glycine-activated currents through recombinant α3GlyRs expressed in HEK293 cells. As previously shown 22,25,27,28 , EP2-R stimulation with PGE 2 (10 μM) decreased the amplitude of glycine-evoked currents ( Fig. 1A-C).…”

Section: Resultssupporting

confidence: 86%

“…In order to explore the impact of the activation of PKA signaling pathway on the elementary ion channel properties, we next performed single-channel recordings of α3GlyRs. In cells co-expressing bPAC and α3GlyRs, in the absence of light, the activation of α3GlyRs resulted in single-channel currents with an average amplitude of 5.47 ± 0.13 pA at +60 mV, as previously shown 27,32,33 . The single-channel amplitudes were stable during 12 minutes of recordings (P = 0.63, paired t-test) ( Fig.…”

Section: Resultssupporting

confidence: 77%

“…EP2-R stimulation increases cAMP and subsequently promote PKA-dependent phosphorylation of the α3GlyR on the S346 residue within the ICD, decreasing the amplitude of glycinergic currents and enhancing the excitability of dorsal horn excitatory neurons. Interestingly, the relevance of α3GlyRs in pain sensitization has been highlighted by the recent characterization of allosteric modulators targeting GlyRs [26][27][28][29] . These reports have shown that compounds potentiating α3GlyR activity are able to reduce chronic pain symptoms in rodents.…”

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confidence: 99%

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Modulation of glycine receptor single-channel conductance by intracellular phosphorylation

Moraga-Cid

Martín

Lara

et al. 2020

Sci Rep

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Glycine receptors (GlyRs) are anion-permeable pentameric ligand-gated ion channels (pLGICs). The GlyR activation is critical for the control of key neurophysiological functions, such as motor coordination, respiratory control, muscle tone and pain processing. The relevance of the GlyR function is further highlighted by the presence of abnormal glycinergic inhibition in many pathophysiological states, such as hyperekplexia, epilepsy, autism and chronic pain. In this context, previous studies have shown that the functional inhibition of GlyRs containing the α3 subunit is a pivotal mechanism of pain hypersensitivity. This pathway involves the activation of EP2 receptors and the subsequent PKAdependent phosphorylation of α3GlyRs within the intracellular domain (ICD), which decrease the GlyR-associated currents and enhance neuronal excitability. Despite the importance of this mechanism of glycinergic dis-inhibition associated with dysfunctional α3GlyRs, our current understanding of the molecular events involved is limited. Here, we report that the activation of PKA signaling pathway decreases the unitary conductance of α3GlyRs. We show in addition that the substitution of the PKAtargeted serine with a negatively charged residue within the ICD of α3GlyRs and of chimeric receptors combining bacterial GLic and α3GlyR was sufficient to generate receptors with reduced conductance. Thus, our findings reveal a potential biophysical mechanism of glycinergic dis-inhibition and suggest that post-translational modifications of the ICD, such as phosphorylation, may shape the conductance of other pLGICs. Glycine receptors (GlyRs) belong to the pentameric ligand-gated ion channel (pLGIC) family. GlyRs are anion-permeable channels, allowing the fast influx of chloride and the control of neuronal excitability. An individual GlyR subunit is composed by an extracellular domain (ECD), four transmembrane domains (TM1-4) and an intracellular domain between the TM3 and TM4 domains (ICD) 1-4. To date, a single β subunit and four α subunits (α1-4) has been described. The α subunits share a high degree of sequence identity (≈75%). Nevertheless, they exhibit important differences in their biophysical and pharmacological properties as well as in their distribution along the CNS 1,3,4. In the mammalian CNS, GlyR activity critically controls neurophysiological functions such as motor coordination, respiratory control, muscle tone, as well as pain processing 2,3,5-13. The importance of glycinergic inhibition was first recognized in studies using the GlyR antagonist strychnine 14,15. Later, genetic studies found that mutations in the GlyR α1 and β genes are linked to hyperekplexia in humans 16. More recent evidence has shown that specific GlyR subunits may play key roles in several diseases. For example, while the α1 subunit has been linked to tumorigenesis and alcohol intoxication 17,18 , mutations in the α2 subunit have been linked to autism 19. Alterations in the RNA processing of α3 subunits generates hyperactive receptors, which have been rela...

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 77%

mentioning

confidence: 99%

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Modulation of glycine receptor single-channel conductance by intracellular phosphorylation

Moraga-Cid

Martín

Lara

et al. 2020

Sci Rep

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Nutrigenomics, Epigenetics and Pain in Cancer

Pirouzpanah

2017

Cancer Genetics and Psychotherapy

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Glycine receptors and glycine transporters: targets for novel analgesics?

Zeilhofer

Acuña

Gingras

et al. 2017

Cell. Mol. Life Sci.

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Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized-among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties.

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Phosphorylation state–dependent modulation of spinal glycine receptors alleviates inflammatory pain

Cited by 50 publications

References 58 publications

Modulation of glycine receptor single-channel conductance by intracellular phosphorylation

Modulation of glycine receptor single-channel conductance by intracellular phosphorylation

Nutrigenomics, Epigenetics and Pain in Cancer

Glycine receptors and glycine transporters: targets for novel analgesics?

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