1-(4-(6-bromobenzo(1-3)dioxol-5-yl)-3a-4-5-9b-tetrahydro-3h-cyclopenta(c)quinolin-8-yl)ethanone and Pain

Recently, we described estrogen and agonists of the G-protein coupled estrogen receptor GPR30 to induce protein kinase C (PKC)ε-dependent pain sensitization. PKCε phosphorylates the ion channel transient receptor potential, vanilloid subclass I (TRPV1) close to a novel microtubule-TRPV1 binding site. We now modeled the binding of tubulin to the TRPV1 C-terminus. The model suggests PKCε phosphorylation of TRPV1-S800 to abolish the tubulin-TRPV1 interaction. Indeed, in vitro PKCε phosphorylation of TRPV1 hindered tubulin-binding to TRPV1. In vivo, treatment of sensory neurons and F-11 cells with estrogen and the GPR30 agonist, G-1, resulted in microtubule destabilization and retraction of microtubules from filopodial structures. We found estrogen and G-1 to regulate the stability of the microtubular network via PKC phosphorylation of the PKCε-phosphorylation site TRPV1-S800. Microtubule disassembly was not, however, dependent on TRPV1 ion conductivity. TRPV1 knock-down in rats inverted the effect of the microtubule-modulating drugs, Taxol and Nocodazole, on estrogen-induced and PKCε-dependent mechanical pain sensitization. Thus, we suggest the C-terminus of TRPV1 to be a signaling intermediate downstream of estrogen and PKCε, regulating microtubule-stability and microtubule-dependent pain sensitization.

Topics: Animals; Binding, Competitive; Cell Line; Cyclopentanes; Estradiol; Estrogens; Ganglia, Spinal; Gene Knockdown Techniques; Ion Channel Gating; Ligands; Male; Microtubules; Models, Molecular; Neurons; Pain; Phosphorylation; Protein Binding; Protein Kinase C-epsilon; Pseudopodia; Quinolines; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Signal Transduction; TRPV Cation Channels; Tubulin