AKAP-dependent sensitization of Cav3.2 channels via the EP4 receptor/cAMP pathway mediates PGE2-induced mechanical hyperalgesia
Article first published online: 16 JAN 2013
© 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society
British Journal of Pharmacology
Volume 168, Issue 3, pages 734–745, February 2013
How to Cite
Sekiguchi, F., Aoki, Y., Nakagawa, M., Kanaoka, D., Nishimoto, Y., Tsubota-Matsunami, M., Yamanaka, R., Yoshida, S. and Kawabata, A. (2013), AKAP-dependent sensitization of Cav3.2 channels via the EP4 receptor/cAMP pathway mediates PGE2-induced mechanical hyperalgesia. British Journal of Pharmacology, 168: 734–745. doi: 10.1111/j.1476-5381.2012.02174.x
- Issue published online: 16 JAN 2013
- Article first published online: 16 JAN 2013
- Accepted manuscript online: 24 AUG 2012 08:04AM EST
- Manuscript Accepted: 15 AUG 2012
- Manuscript Revised: 30 JUL 2012
- Manuscript Received: 10 DEC 2011
- Cav3.2 T-type calcium channel;
- mechanical hyperalgesia;
- EP4 receptor;
- A-kinase anchoring protein 150 (AKAP150)
Background and Purpose
The Cav3.2 isoform of T-type Ca2+ channels (T channels) is sensitized by hydrogen sulfide, a pro-nociceptive gasotransmitter, and also by PKA that mediates PGE2-induced hyperalgesia. Here we examined and analysed Cav3.2 sensitization via the PGE2/cAMP pathway in NG108-15 cells that express Cav3.2 and produce cAMP in response to PGE2, and its impact on mechanical nociceptive processing in rats.
In NG108-15 cells and rat dorsal root ganglion (DRG) neurons, T-channel-dependent currents (T currents) were measured with the whole-cell patch-clamp technique. The molecular interaction of Cav3.2 with A-kinase anchoring protein 150 (AKAP150) and its phosphorylation were analysed by immunoprecipitation/immunoblotting in NG108-15 cells. Mechanical nociceptive threshold was determined by the paw pressure test in rats.
In NG108-15 cells and/or rat DRG neurons, dibutyryl cAMP (db-cAMP) or PGE2 increased T currents, an effect blocked by AKAP St-Ht31 inhibitor peptide (AKAPI) or KT5720, a PKA inhibitor. The effect of PGE2 was abolished by RQ-00015986-00, an EP4 receptor antagonist. AKAP150 was co-immunoprecipitated with Cav3.2, regardless of stimulation with db-cAMP, and Cav3.2 was phosphorylated by db-cAMP or PGE2. In rats, intraplantar (i.pl.) administration of db-cAMP or PGE2 caused mechanical hyperalgesia, an effect suppressed by AKAPI, two distinct T-channel blockers, NNC 55-0396 and ethosuximide, or ZnCl2, known to inhibit Cav3.2 among T channels. Oral administration of RQ-00015986-00 suppressed the PGE2-induced mechanical hyperalgesia.
Conclusion and Implications
Our findings suggest that PGE2 causes AKAP-dependent phosphorylation and sensitization of Cav3.2 through the EP4 receptor/cAMP/PKA pathway, leading to mechanical hyperalgesia in rats.