Clathrin-mediated Endocytosis of Na+,K+-ATPase in Response to Parathyroid Hormone Requires ERK-dependent Phosphorylation of Ser-11 within the α1-Subunit

Syed Jalal Khundmiri, Alejandro M. Bertorello, Nicholas A. Delamere, Eleanor D. Lederer

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

Parathyroid hormone (PTH) inhibits Na+,K+-ATPase activity through protein kinase C- (PKC) and extracellular signal-regulated kinase- (ERK) dependent pathways and increases serine phosphorylation of the α1-subunit. To determine whether specific serine phosphorylation sites within the Na+,K+-ATPase α1-subunit are involved in the Na+,K +-ATPase responses to PTH, we examined the effect of PTH in opossum kidney cells stably transfected with wild type rat Na+,K +-ATPase α1-subunit (WT), serine 11 to alanine mutant α1-subunit (S11A), or serine 18 to alanine mutant α1-subunit (S18A). PTH increased phosphorylation and endocytosis of the Na+,K+-ATPase α 1-subunit into clathrin-coated vesicles in cells transfected with WT and S18A rat Na+,K+-ATPase α1-subunits. PTH did not increase the level of phosphorylation or stimulate translocation of Na+,K+-ATPase α1-subunits into clathrin-coated vesicles in cells transfected with the S11A mutant. PTH inhibited ouabain-sensitive 86Rb uptake and Na+,K +-ATPase activity (ouabain-sensitive ATP hydrolysis) in WT- and S18A-transfected opossum kidney cells but not in S11A-transfected cells. Pretreatment of the cells with the PKC inhibitors and ERK inhibitor blocked PTH inhibition of 86Rb uptake, Na+,K+-ATPase activity, α1-subunit phosphorylation, and endocytosis in WT and S18A cells. Consistent with the notion that ERK phosphorylates Na +,K+-ATPase α1-subunit, ERK was shown to be capable of causing phosphorylation of Na+,K+-ATPase α1-subunit immunoprecipitated from WT and S18A but not from S11A-transfected cells. These results suggest that PTH regulates Na +,K+-ATPase by PKC and ERK-dependent α 1-subunit phosphorylation and that the phosphorylation requires the expression of a serine at the 11 position of the Na+,K +-ATPase α1-subunit.

Original languageEnglish (US)
Pages (from-to)17418-17427
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number17
DOIs
StatePublished - Apr 23 2004

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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