Effects of extracellular nucleotides in the thyroid: P2Y 2 receptor-mediated ERK1/2 activation and c-Fos induction in PC Cl3 cells

Abstract

Aim of the present paper was to investigate the signaling pathways of P2Y 2 in rat thyroid PC Cl3 cell line and its effects on proliferation. This study demonstrates that P2Y 2 activation provoked: (a) a cytosol-to-membrane translocation of PKC-α, -βI and -ε; (b) the phosphorylation of the extra cellular signal-regulated kinases 1 and 2 (ERK1/2); (c) the expression of c-Fos protein; (d) no effects on the G1/S progression and overall cell proliferation. The P2Y 2-stimulated ERK1/2 phosphorylation was: (a) completely blocked by PD098059, a mitogen-activated protein kinase (MEK) inhibitor or by W-7, a Ca 2+-calmodulin (CaM) antagonist; (b) reduced by GF109203X, inhibitor of PKCs, or AG1478, inhibitor of EGFR tyrosine kinase, or LY294002/wortmannin, inhibitors of phosphoinositide 3-kinases, or cytochalasin D, inhibitor of actin microfilament bundles polymerization. The c-Fos induction was greatly diminished by Gö6976 or PD098059, and completely abolished when combined. In conclusion, data indicate that the P2Y 2-induced phosphorylation of ERK1/2 and the induction of c-Fos are due to the operation of CaM, with PKC, PI3K, EGFR and receptor endocytosis mechanisms endorsing the signalling. On the other hand, no mitogenic effects of P2Y 2 are whatsoever noticed in PC Cl3 cells.