Parathyroid Hormone Regulates Na‐K ATPase through ERK‐dependent cPLA2 phosphorylation

TL;DRAbstract

We have demonstrated that PTH regulates Na‐K ATPase (Na‐K) through ERK‐dependent PKC alpha activation that results in translocation of PKC alpha to the plasma membrane and association with Na‐K. Based on previous data showing an inhibitory effect of PLA2 products on Na‐K activity, we hypothesized that PTH‐stimulated ERK activates PKC alpha through a PLA2 dependent mechanism. To address this hypothesis, we examined the effect of PTH on PLA2 and the effect of cPLA2 products on activation of PKC alpha in opossum kidney (OK) cells, a model of renal proximal tubule. PTH 1–34 100 nM increased phosphorylation of cPLA2 in OK cells as determined by immunoblot with phosphoPLA2 antibodies. PTH‐stimulated phosphorylation of cPLA2 was prevented by pretreatment with U0126, an inhibitor of MEK1, but not by a peptide inhibitor of PKC alpha. Treatment of OK cells with 20‐HETE or arachidonic acid (AA) (products of cPLA2) decreased Na‐K activity by 25–30% as measured by 86Rb uptake and decreased Na‐K mem

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