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Free keywords:
Animals; Binding, Competitive; Cell Line; Cyclopentanes/pharmacology; Estradiol/*pharmacology; Estrogens/*pharmacology/physiology; Ganglia, Spinal/cytology; Gene Knockdown Techniques; Ion Channel Gating; Ligands; Male; Microtubules/*drug effects/ultrastructure; Models, Molecular; Neurons/drug effects/ultrastructure; Pain/physiopathology; Phosphorylation; Protein Binding; Protein Kinase C-epsilon/physiology; Pseudopodia/ultrastructure; Quinolines/pharmacology; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled/agonists; Signal Transduction; TRPV Cation Channels/genetics/*metabolism; Tubulin/metabolism
Abstract:
Recently, we described estrogen and agonists of the G-protein coupled estrogen receptor GPR30 to induce protein kinase C (PKC)epsilon-dependent pain sensitization. PKCepsilon 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 PKCepsilon phosphorylation of TRPV1-S800 to abolish the tubulin-TRPV1 interaction. Indeed, in vitro PKCepsilon 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 PKCepsilon-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 PKCepsilon-dependent mechanical pain sensitization. Thus, we suggest the C-terminus of TRPV1 to be a signaling intermediate downstream of estrogen and PKCepsilon, regulating microtubule-stability and microtubule-dependent pain sensitization.
