Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 287, Issue 28, Pages 23948-23957Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M112.342998
Keywords
-
Categories
Funding
- National Health and Medical Research Council Program Grant [569927]
- Australian Research Council Project Grant [DP1093177]
- Australian Research Council [DP1093177] Funding Source: Australian Research Council
Ask authors/readers for more resources
alpha-Conotoxins Vc1.1 and RgIA are small peptides isolated from the venom of marine cone snails. They have effective anti-nociceptive actions in rat models of neuropathic pain. Pharmacological studies in rodent dorsal root ganglion (DRG) show their analgesic effect is mediated by inhibition of N-type (Ca(v)2.2) calcium channels via a pathway involving gamma-aminobutyric acid type B (GABA(B)) receptor. However, there is no direct demonstration that functional GABA(B) receptors are needed for inhibition of the Cav2.2 channel by analgesic alpha-conotoxins. This study examined the effect of the GABA(B) agonist baclofen and alpha-conotoxins Vc1.1 and RgIA on calcium channel currents after transient knockdown of the GABA(B) receptor using RNA interference. Isolated rat DRG neurons were transfected with small interfering RNAs(siRNA) targeting GABA(B) subunits R1 and R2. Efficient knockdown of GABA(B) receptor expression at mRNA and protein levels was confirmed by quantitative real time PCR (qRT-PCR) and immunocytochemical analysis, respectively. Whole-cell patch clamp recordings conducted 2-4 days after transfection showed that inhibition of N-type calcium channels in response to baclofen, Vc1.1 and RgIA was significantly reduced in GABA(B) receptor knockdown DRG neurons. In contrast, neurons transfected with a scrambled nontargeting siRNA were indistinguishable from untransfected neurons. In the HEK 293 cell heterologous expression system, Vc1.1 and RgIA inhibition of Ca(v)2.2 channels needed functional expression of both human GABA(B) receptor subunits. Together, these results confirm that GABA(B) receptors must be activated for the modulation of N-type (Ca(v)2.2) calcium channels by analgesic alpha-conotoxins Vc1.1 and RgIA.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available