Acute regulation of Na+/H+ exchanger NHE3 by parathyroid hormone via NHE3 phosphorylation and dynamin-dependent endocytosis.
Parathyroid hormone (PTH) is a potent inhibitor of mammalian renal proximal tubule Na(+) transport via its action on the apical membrane Na(+)/H(+) exchanger NHE3. In the opossum kidney cell line, inhibition of NHE3 activity was detected from 5 to 45 min after PTH addition. Increase in NHE3 phosphorylation on multiple serines was evident after 5 min of PTH, but decrease in surface NHE3 antigen was not detectable until after 30 min of PTH. The decrease in surface NHE3 antigen was due to increased NHE3 endocytosis. When endocytic trafficking was arrested with a dominant negative dynamin mutant (K44A), the early inhibition (5 min) of NHE3 activity by PTH was not affected, whereas the late inhibition (30 min) and decreased surface NHE3 antigen induced by PTH were abrogated. We conclude that PTH acutely inhibits NHE3 activity in a biphasic fashion by NHE3 phosphorylation followed by dynamin-dependent endocytosis.
Collazo
R
R
Medical Service, Department of Veterans Affairs Medical Center and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
Fan
L
L
Hu
M C
MC
Zhao
H
H
Wiederkehr
M R
MR
Moe
O W
OW
D000818:Animals; D000954:Antigens, Surface / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects*; D034281:Dynamins; D004705:Endocytosis / Q000187:drug effects*; D005453:Fluorescence; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D009893:Opossums; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010748:Phosphopeptides / Q000032:analysis / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D014162:Transfection
D000954:Antigens, Surface; D010281:Parathyroid Hormone; D010748:Phosphopeptides; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D020558:GTP Phosphohydrolases; D034281:Dynamins