TY - JOUR
T1 - Critical role for Epac1 in inflammatory pain controlled by GRK2-mediated phosphorylation of Epac1
AU - Singhmar, Pooja
AU - Huo, Xiaojiao
AU - Eijkelkamp, Niels
AU - Berciano, Susana Rojo
AU - Baameur, Faiza
AU - Mei, Fang C.
AU - Zhu, Yingmin
AU - Cheng, Xiaodong
AU - Hawke, David
AU - Mayor, Federico
AU - Murga, Cristina
AU - Heijnen, Cobi J.
AU - Kavelaars, Annemieke
N1 - Funding Information:
We thank Drs. F. Zwartkruis and J. Bos (University Medical Center Utrecht) and Dr. J. Zhang (Johns Hopkins University School of Medicine) for sharing Epac1 constructs; Dr. H. L. D. M. Willemen (University Medical Center Utrecht) for providing GRK2 constructs; Mr. B. Igwe for contributing to subcloning; Dr. J. Zhong (Baylor College of Medicine) for help with image capture; and Dr. John Wood (University College London) for facilitating the electrophysiology experiments. This work was supported by National Institutes of Health Grants R01 NS073939, R01 NS074999, R01 GM066170, and R01GM106218 and High-End Instrumentation Program 1S10OD012304-01; Cancer Prevention Research Institute of Texas Core Facility Grant RP130397 (a University of Texas System Science and Technology Acquisition and Retention grant); Ministerio de Economía y Competitividad Grant SAF2014-55511-R; Comunidad de Madrid Grant S2010/BMD-2332 (Inter-Disciplinary Research Network); Ministerio Sanidad y Consumo-Instituto Carlos III Cardiovascular Network Grant RD12/0042/0012; a European Foundation for the Study of Diabetes- Novo Nordisk grant; and by Universidad Autónoma de Madrid-Banco de Santander.
PY - 2016/3/15
Y1 - 2016/3/15
N2 - cAMP signaling plays a key role in regulating pain sensitivity. Here, we uncover a previously unidentified molecular mechanism in which direct phosphorylation of the exchange protein directly activated by cAMP 1 (EPAC1) by G protein kinase 2 (GRK2) suppresses Epac1-to-Rap1 signaling, thereby inhibiting persistent inflammatory pain. Epac1-/- mice are protected against inflammatory hyperalgesia in the complete Freund's adjuvant (CFA) model. Moreover, the Epac-specific inhibitor ESI-09 inhibits established CFA-induced mechanical hyperalgesia without affecting normal mechanical sensitivity. At the mechanistic level, CFA increased activity of the Epac target Rap1 in dorsal root ganglia of WT, but not of Epac1-/-, mice. Using sensory neuronspecific overexpression of GRK2 or its kinase-dead mutant in vivo, we demonstrate that GRK2 inhibits CFA-induced hyperalgesia in a kinase activity-dependent manner. In vitro, GRK2 inhibits Epac1-to-Rap1 signaling by phosphorylation of Epac1 at Ser-108 in the Disheveled/ Egl-10/pleckstrin domain. This phosphorylation event inhibits agonist-induced translocation of Epac1 to the plasma membrane, thereby reducing Rap1 activation. Finally, we show that GRK2 inhibits Epac1-mediated sensitization of the mechanosensor Piezo2 and that Piezo2 contributes to inflammatory mechanical hyperalgesia. Collectively, these findings identify a key role of Epac1 in chronic inflammatory pain and a molecular mechanism for controlling Epac1 activity and chronic pain through phosphorylation of Epac1 at Ser-108. Importantly, using the Epac inhibitor ESI-09, we validate Epac1 as a potential therapeutic target for chronic pain.
AB - cAMP signaling plays a key role in regulating pain sensitivity. Here, we uncover a previously unidentified molecular mechanism in which direct phosphorylation of the exchange protein directly activated by cAMP 1 (EPAC1) by G protein kinase 2 (GRK2) suppresses Epac1-to-Rap1 signaling, thereby inhibiting persistent inflammatory pain. Epac1-/- mice are protected against inflammatory hyperalgesia in the complete Freund's adjuvant (CFA) model. Moreover, the Epac-specific inhibitor ESI-09 inhibits established CFA-induced mechanical hyperalgesia without affecting normal mechanical sensitivity. At the mechanistic level, CFA increased activity of the Epac target Rap1 in dorsal root ganglia of WT, but not of Epac1-/-, mice. Using sensory neuronspecific overexpression of GRK2 or its kinase-dead mutant in vivo, we demonstrate that GRK2 inhibits CFA-induced hyperalgesia in a kinase activity-dependent manner. In vitro, GRK2 inhibits Epac1-to-Rap1 signaling by phosphorylation of Epac1 at Ser-108 in the Disheveled/ Egl-10/pleckstrin domain. This phosphorylation event inhibits agonist-induced translocation of Epac1 to the plasma membrane, thereby reducing Rap1 activation. Finally, we show that GRK2 inhibits Epac1-mediated sensitization of the mechanosensor Piezo2 and that Piezo2 contributes to inflammatory mechanical hyperalgesia. Collectively, these findings identify a key role of Epac1 in chronic inflammatory pain and a molecular mechanism for controlling Epac1 activity and chronic pain through phosphorylation of Epac1 at Ser-108. Importantly, using the Epac inhibitor ESI-09, we validate Epac1 as a potential therapeutic target for chronic pain.
KW - Chronic pain
KW - Epac1
KW - Epac1 translocation
KW - GRK2
KW - Piezo2
UR - http://www.scopus.com/inward/record.url?scp=84962583653&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84962583653&partnerID=8YFLogxK
U2 - 10.1073/pnas.1516036113
DO - 10.1073/pnas.1516036113
M3 - Article
C2 - 26929333
AN - SCOPUS:84962583653
SN - 0027-8424
VL - 113
SP - 3036
EP - 3041
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 11
ER -