Novel regulation of Na, K-ATPase by Src tyrosine kinases in cortical neurons.
The Na+, K+-ATPase or Na+, K+-pump plays a critical role in ion homeostasis and many cellular events. The Na+, K+-pump activity is regulated by serine/threonine phosphorylation, the role of tyrosine kinases in the regulation, however, is obscure. We now present novel evidence showing that tyrosine phosphorylation activates the Na+, K+-pump in cortical neurons. The electrogenic activity of the Na+, K+-pump was measured using whole-cell voltage clamp. A tonic activity was revealed by an inward current induced by the specific inhibitor ouabain or strophanthidin; an outward current due to activation of the pump was triggered by raising extracellular K+. The inward and outward currents were attenuated by the tyrosine kinase inhibitor genistein, herbimycin A, or lavendustin A, while blocking tyrosine phosphatases increased the pump current. Down-regulation of the pump current was also seen with the Src inhibitor PP1 and intracellularly applied anti-Lyn or anti-Yes antibody. Consistently, intracellular application of Lyn kinase up-regulated the pump current. Immunoprecipitation and western blotting showed tyrosine phosphorylation and a direct interaction between Lyn and the alpha3 subunit of the Na+, K+-pump. The tyrosine phosphorylation of the alpha3 subunit was reduced by serum deprivation. These data suggest that the Na+, K+-ATPase activity in central neurons is regulated by specific Src tyrosine kinases via a protein-protein mechanism and may play a role in apoptosis.
Wang
Xue Qing
XQ
Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Yu
Shan Ping
SP
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology; D018920:Coculture Techniques; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D021122:Protein Subunits / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000906:Antibodies; D004791:Enzyme Inhibitors; D021122:Protein Subunits; D014443:Tyrosine; D012964:Sodium; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium