ET(B) receptor activation causes exocytic insertion of NHE3 in OKP cells.
Endothelin-1 (ET-1) activates sodium/hydrogen exchanger 3 (NHE3) in opossum kidney clone P (OKP) cells expressing ET(B) receptors. ET-1 (10(-8) M) caused a two- to threefold increase in apical membrane NHE3 (assessed by surface biotinylation), in the absence of a change in total cellular NHE3. A maximal effect was achieved within 15 min. The increase in apical NHE3 was not blocked by cytochalasin D but was blocked by latrunculin B, which also prevented the ET-1-induced increase in NHE3 activity. Endocytic internalization of NHE3, measured as protection of biotinylated NHE3 from the membrane-impermeant, sulfhydryl-reducing agent MesNa was minimal within 35 min and was not regulated by ET-1. Exocytic insertion of NHE3, measured as the appearance of biotinylated NHE3 after the blockade of reactive sites with sulfo-NHS-acetate, was increased in response to ET-1. These studies demonstrate that ET-1 induces net trafficking of NHE3 to the apical membrane that is mediated by enhanced exocytic insertion and is required for increased NHE3 activity.
Peng
Y
Y
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Amemiya
M
M
Yang
X
X
Fan
L
L
Moe
O W
OW
Yin
H
H
Preisig
P A
PA
Yanagisawa
M
M
Alpern
R J
RJ
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D019921:Biotinylation; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000502:physiology*; D007700:Kinetics; D009893:Opossums; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
D019332:Endothelin-1; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D000469:Alkaline Phosphatase