Insulin increases plasma membrane content and reduces phosphorylation of Na+-K+ pump α1-subunit in HEK-293 cells

Gary Sweeney, Wenyan Niu, Victor Canfield, Robert Levenson, Amira Klip

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Insulin stimulates K+ uptake and Na+ efflux via the Na+-K+ pump in kidney, skeletal muscle, and brain. The mechanism of insulin action in these tissues differs, in part, because of differences in the isoform complement of the catalytic α-subunit of the Na+-K+ pump. To analyze specifically the effect of insulin on the α1-isoform of the pump, we have studied human embryonic kidney (HEK)-293 cells stably transfected with the rat Na+-K+ pump α1-isoform tagged on its first exofacial loop with a hemagglutinin (HA) epitope. The plasma membrane content of α1-subunits was quantitated by binding a specific HA antibody to intact cells. Insulin rapidly increased the number of α1-subunits at the cell surface. This gain was sensitive to the phosphatidylinositol (PI) 3-kinase inhibitor wortmannin and to the protein kinase C (PKC) inhibitor bisindolylmaleimide. Furthermore, the insulin-stimulated gain in surface α1-subunits correlated with an increase in the binding of an antibody that recognizes only the nonphosphorylated form of α1 (at serine-18). These results suggest that insulin regulates the Na+-K+ pump in HEK-293 cells, at least in part, by decreasing serine phosphorylation and increasing plasma membrane content of α1-subunits via a signaling pathway involving PI 3-kinase and PKC.

Original languageEnglish (US)
Pages (from-to)C1797-C1803
JournalAmerican Journal of Physiology - Cell Physiology
Volume281
Issue number6 50-6
DOIs
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cell Biology

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