Abstract
The voltage-activated T-type calcium channel (CaV3.2) and the G protein-coupled neurokinin 1 (NK1) receptor are expressed in peripheral tissues and in central neurons, in which they participate in diverse physiological processes, including neurogenic inflammation and nociception. In the present report, we demonstrate that recombinant CaV3.2 channels are reversibly inhibited by NK1 receptors when both proteins are transiently coexpressed in human embryonic kidney 293 cells. We found that the voltage-dependent macroscopic properties of CaV3.2 currents were unaffected during NK1 receptor-mediated inhibition. However, inhibition was attenuated in cells coexpressing either the dominant-negative Gαq Q209L/D277N or the regulator of G protein signaling (RGS) proteins 2 (RGS2) and 3T (RGS3T), which are effective antagonists of Gαq/11. By contrast, inhibition was unaffected in cells coexpressing human rod transducin (Gαt), which buffers Gβγ. Channel inhibition was blocked by 1-[6-[[17β-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122) and bisindolylmaleimide I, selective inhibitors of phospholipase Cβ and protein kinase C (PKC), respectively. Inhibition was occluded by application of the PKC activator phorbol-12-myristate-13-acetate. Altogether, these data indicate that NK1 receptors inhibit CaV3.2 channels through a voltage-independent signaling pathway that involves Gαq/11, phospholipase Cβ, and PKC. Our results provide novel evidence regarding the mechanisms underlying T-type calcium channel modulation by G protein-coupled receptors. Functional coupling between CaV3.2 channels and NK1 receptors may be relevant in neurogenic inflammation, neuronal rhythmogenesis, nociception, and other physiological processes.
Footnotes
-
This work was supported by the Consejo Nacional de Ciencia y Tecnología-México [Grant 61248]; and the Universidad Autónoma de San Luis Potosí [Grants C08-FRC-02-53.53, C09-FRC-07-28.28].
-
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.109.058727.
-
ABBREVIATIONS:
- NK1
- neurokinin 1
- PKC
- protein kinase C
- NKA
- neurokinin A
- HEK
- human embryonic kidney
- EGFP
- enhanced green fluorescent protein
- GPCR
- G-protein coupled receptor
- Gαt
- rod transducin
- RGS
- regulator of G protein signaling
- Bis
- bisindolylmaleimide
- PLC
- phospholipase C
- PMA
- phorbol-12-myristate-13-acetate
- U73122
- 1-[6-[[17β-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione
- SP
- substance P
- DRG
- dorsal root ganglion.
- Received June 22, 2009.
- Accepted October 5, 2009.
- Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|