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A role for Piezo2 in EPAC1-dependent mechanical allodynia.

Eijkelkamp N, Linley JE, Torres JM, Bee L, Dickenson AH, Gringhuis M, Minett MS, Hong GS, Lee E, Oh U, Ishikawa Y, Zwartkuis FJ, Cox JJ, Wood JN - Nat Commun (2013)

Bottom Line: Human Piezo2 produces large mechanically gated currents that are enhanced by the activation of the cAMP-sensor Epac1 or cytosolic calcium but are unaffected by protein kinase C or protein kinase A and depend on the integrity of the cytoskeleton.Piezo2 knockdown also enhanced thresholds for light touch.Finally, 8-pCPT sensitizes responses to innocuous mechanical stimuli without changing the electrical excitability of sensory fibres.

View Article: PubMed Central - PubMed

Affiliation: Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, UK. N.Eijkelkamp@umcutrecht.nl

ABSTRACT
Aberrant mechanosensation has an important role in different pain states. Here we show that Epac1 (cyclic AMP sensor) potentiation of Piezo2-mediated mechanotransduction contributes to mechanical allodynia. Dorsal root ganglia Epac1 mRNA levels increase during neuropathic pain, and nerve damage-induced allodynia is reduced in Epac1-/- mice. The Epac-selective cAMP analogue 8-pCPT sensitizes mechanically evoked currents in sensory neurons. Human Piezo2 produces large mechanically gated currents that are enhanced by the activation of the cAMP-sensor Epac1 or cytosolic calcium but are unaffected by protein kinase C or protein kinase A and depend on the integrity of the cytoskeleton. In vivo, 8-pCPT induces long-lasting allodynia that is prevented by the knockdown of Epac1 and attenuated by mouse Piezo2 knockdown. Piezo2 knockdown also enhanced thresholds for light touch. Finally, 8-pCPT sensitizes responses to innocuous mechanical stimuli without changing the electrical excitability of sensory fibres. These data indicate that the Epac1-Piezo2 axis has a role in the development of mechanical allodynia during neuropathic pain.

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8-pCPT enhances rapidly adapting mechanically evoked currents in large diameter sensory neurons.(a) Stimulus–response curve of rapidly adapting currents evoked by mechanical stimulation before and 15 min after 8-pCPT or vehicle administration (vehicle, n=13; 8-pCPT, n=17). (b) Time course of peak currents evoked by a ~12.5-μm membrane deflection after administration of 8-pCPT into the bath solution. Repeated measures one-way analysis of variance: time, P<0.05; treatment, P>.05; interaction: P<0.01 (n=14). (c) Threshold of activation was determined as mechanical stimulus that elicited a current >20 pA. The decrease in threshold of activation after 8-pCPT was calculated as percentage of baseline thresholds. (d) Representative example of whole-cell voltage clamp traces from a large diameter mouse DRG neuron with a narrow action potential width in response to increasing membrane deformation (holding potential −60 mV) before and after 8-pCPT or vehicle administration. All data are expressed as mean±s.e.m. (a–b) Data were analysed using two-way analysis of variance followed by the Bonferroni post hoc test. (d) Data are analysed by t-test. *P<0.05, **P<0.01, ***P<0.001.
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f2: 8-pCPT enhances rapidly adapting mechanically evoked currents in large diameter sensory neurons.(a) Stimulus–response curve of rapidly adapting currents evoked by mechanical stimulation before and 15 min after 8-pCPT or vehicle administration (vehicle, n=13; 8-pCPT, n=17). (b) Time course of peak currents evoked by a ~12.5-μm membrane deflection after administration of 8-pCPT into the bath solution. Repeated measures one-way analysis of variance: time, P<0.05; treatment, P>.05; interaction: P<0.01 (n=14). (c) Threshold of activation was determined as mechanical stimulus that elicited a current >20 pA. The decrease in threshold of activation after 8-pCPT was calculated as percentage of baseline thresholds. (d) Representative example of whole-cell voltage clamp traces from a large diameter mouse DRG neuron with a narrow action potential width in response to increasing membrane deformation (holding potential −60 mV) before and after 8-pCPT or vehicle administration. All data are expressed as mean±s.e.m. (a–b) Data were analysed using two-way analysis of variance followed by the Bonferroni post hoc test. (d) Data are analysed by t-test. *P<0.05, **P<0.01, ***P<0.001.

Mentions: Sensory neurons are intrinsically mechanosensitive and different types of mechanically gated current can be identified in the cell bodies of sensory neurons in vitro1516. Neurons associated with detection of touch express low threshold rapidly adapting (RA) mechanically gated currents2. We asked whether activation of the cAMP-sensor Epac leads to changes in mechanically evoked RA currents in DRG neurons? Large diameter neurons (>35 μm) with fast action potentials (width of action potential<1 ms) were mechanically distended17. Application of the Epac-selective cAMP analogue 8-pCPT shifted the stimulus response curves of mechanically evoked RA currents to the left, resulting in increased currents in response to mechanical stimuli (~2-fold increase in inward current at a stimulus intensity of 12 μm) (Fig. 2a). 8-pCPT time dependently enhanced mechanically activated peak currents evoked by a ~12.5-μm distension that plateaued after ~15 min (Fig. 2b). Finally, 15 min after application of 8-pCPT the threshold of activation of RA currents was reduced by ~24% (Fig. 2c). Application of vehicle did not have any effect on mechanically evoked current sizes (Fig. 2).


A role for Piezo2 in EPAC1-dependent mechanical allodynia.

Eijkelkamp N, Linley JE, Torres JM, Bee L, Dickenson AH, Gringhuis M, Minett MS, Hong GS, Lee E, Oh U, Ishikawa Y, Zwartkuis FJ, Cox JJ, Wood JN - Nat Commun (2013)

8-pCPT enhances rapidly adapting mechanically evoked currents in large diameter sensory neurons.(a) Stimulus–response curve of rapidly adapting currents evoked by mechanical stimulation before and 15 min after 8-pCPT or vehicle administration (vehicle, n=13; 8-pCPT, n=17). (b) Time course of peak currents evoked by a ~12.5-μm membrane deflection after administration of 8-pCPT into the bath solution. Repeated measures one-way analysis of variance: time, P<0.05; treatment, P>.05; interaction: P<0.01 (n=14). (c) Threshold of activation was determined as mechanical stimulus that elicited a current >20 pA. The decrease in threshold of activation after 8-pCPT was calculated as percentage of baseline thresholds. (d) Representative example of whole-cell voltage clamp traces from a large diameter mouse DRG neuron with a narrow action potential width in response to increasing membrane deformation (holding potential −60 mV) before and after 8-pCPT or vehicle administration. All data are expressed as mean±s.e.m. (a–b) Data were analysed using two-way analysis of variance followed by the Bonferroni post hoc test. (d) Data are analysed by t-test. *P<0.05, **P<0.01, ***P<0.001.
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f2: 8-pCPT enhances rapidly adapting mechanically evoked currents in large diameter sensory neurons.(a) Stimulus–response curve of rapidly adapting currents evoked by mechanical stimulation before and 15 min after 8-pCPT or vehicle administration (vehicle, n=13; 8-pCPT, n=17). (b) Time course of peak currents evoked by a ~12.5-μm membrane deflection after administration of 8-pCPT into the bath solution. Repeated measures one-way analysis of variance: time, P<0.05; treatment, P>.05; interaction: P<0.01 (n=14). (c) Threshold of activation was determined as mechanical stimulus that elicited a current >20 pA. The decrease in threshold of activation after 8-pCPT was calculated as percentage of baseline thresholds. (d) Representative example of whole-cell voltage clamp traces from a large diameter mouse DRG neuron with a narrow action potential width in response to increasing membrane deformation (holding potential −60 mV) before and after 8-pCPT or vehicle administration. All data are expressed as mean±s.e.m. (a–b) Data were analysed using two-way analysis of variance followed by the Bonferroni post hoc test. (d) Data are analysed by t-test. *P<0.05, **P<0.01, ***P<0.001.
Mentions: Sensory neurons are intrinsically mechanosensitive and different types of mechanically gated current can be identified in the cell bodies of sensory neurons in vitro1516. Neurons associated with detection of touch express low threshold rapidly adapting (RA) mechanically gated currents2. We asked whether activation of the cAMP-sensor Epac leads to changes in mechanically evoked RA currents in DRG neurons? Large diameter neurons (>35 μm) with fast action potentials (width of action potential<1 ms) were mechanically distended17. Application of the Epac-selective cAMP analogue 8-pCPT shifted the stimulus response curves of mechanically evoked RA currents to the left, resulting in increased currents in response to mechanical stimuli (~2-fold increase in inward current at a stimulus intensity of 12 μm) (Fig. 2a). 8-pCPT time dependently enhanced mechanically activated peak currents evoked by a ~12.5-μm distension that plateaued after ~15 min (Fig. 2b). Finally, 15 min after application of 8-pCPT the threshold of activation of RA currents was reduced by ~24% (Fig. 2c). Application of vehicle did not have any effect on mechanically evoked current sizes (Fig. 2).

Bottom Line: Human Piezo2 produces large mechanically gated currents that are enhanced by the activation of the cAMP-sensor Epac1 or cytosolic calcium but are unaffected by protein kinase C or protein kinase A and depend on the integrity of the cytoskeleton.Piezo2 knockdown also enhanced thresholds for light touch.Finally, 8-pCPT sensitizes responses to innocuous mechanical stimuli without changing the electrical excitability of sensory fibres.

View Article: PubMed Central - PubMed

Affiliation: Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, UK. N.Eijkelkamp@umcutrecht.nl

ABSTRACT
Aberrant mechanosensation has an important role in different pain states. Here we show that Epac1 (cyclic AMP sensor) potentiation of Piezo2-mediated mechanotransduction contributes to mechanical allodynia. Dorsal root ganglia Epac1 mRNA levels increase during neuropathic pain, and nerve damage-induced allodynia is reduced in Epac1-/- mice. The Epac-selective cAMP analogue 8-pCPT sensitizes mechanically evoked currents in sensory neurons. Human Piezo2 produces large mechanically gated currents that are enhanced by the activation of the cAMP-sensor Epac1 or cytosolic calcium but are unaffected by protein kinase C or protein kinase A and depend on the integrity of the cytoskeleton. In vivo, 8-pCPT induces long-lasting allodynia that is prevented by the knockdown of Epac1 and attenuated by mouse Piezo2 knockdown. Piezo2 knockdown also enhanced thresholds for light touch. Finally, 8-pCPT sensitizes responses to innocuous mechanical stimuli without changing the electrical excitability of sensory fibres. These data indicate that the Epac1-Piezo2 axis has a role in the development of mechanical allodynia during neuropathic pain.

Show MeSH
Related in: MedlinePlus