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  • Cyclic adenosine monophosphate-dependent activation of transient receptor potential vanilloid 4 (TRPV4) channels in osteoblast-like MG-63 cells.

Cyclic adenosine monophosphate-dependent activation of transient receptor potential vanilloid 4 (TRPV4) channels in osteoblast-like MG-63 cells.

Cellular signalling (2019-11-30)
Arleth Pozo, Marine Regnier, Jérôme Lizotte, Corine Martineau, Tatiana Scorza, Robert Moreau
RESUMEN

Parathyroid hormone (PTH) directly interacts with bone remodeling osteoblasts and osteocytes expressing the G-protein coupled receptor PTH receptor 1 (PTH1R), and its osteoanabolic effects mostly involve the cAMP/PKA signaling cascade. Considering that PTH-dependent calcium entry in rat enterocytes is reproduced by the adenylate cyclase agonist forskolin or by cAMP analogues, possible involvement of calcium as a second messenger in PTH-dependent cAMP signaling was investigated in MG-63 cells. First, Ca2+ influx was confirmed in Fluo3-loaded MG-63 cells treated with a cell-permeable cAMP analog. Second, PTH (1-34) and forskolin promoted calcium influxes that were completely abrogated by the PKA inhibitor H-89. Ca2+ entry was not reproduced when PTH (1-34) was combined with the PKC-activating competitor PTH (3-34). Vanilloid transient potential (TRPV) channel inhibitor Ruthenium Red, but not a voltage-dependent calcium channel (VDCC) inhibitor nifedipine, efficiently stunted Ca2+ entry, and comparable abrogation was reproduced in cells treated with TRPV4-selective inhibitor RN-1734 or transfected with TRPV4-specific siRNA. Interestingly, PTH-driven Ca2+ through TRPV4 significantly inhibited MG63 cell migration through a mechanism requiring extracellular Ca2+. In contrast, the inhibitory effects of forskolin on migration were refractory to TRPV4 silencing or to RN-1734. Altogether, our results indicate that single treatment with PTH (1-34) promotes extracellular calcium entry through TRPV4 channels in MG-63 cells through a cAMP/PKA-dependent mechanism, and that this influx affects cell migration.

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Sigma-Aldrich
Fluo-3, suitable for fluorescence, ~70%
Sigma-Aldrich
MISSION® esiRNA, targeting human TRPV4