ENaC subunit-subunit interactions and inhibition by syntaxin 1A.
Amiloride-sensitive epithelial Na(+) channels (ENaCs) are subject to modulation by many factors. Recent data have also linked the N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) machinery to this regulation of ENaC, but the molecular mechanisms that underlie this modulation are poorly understood. In this study, we demonstrate that syntaxin 1A physically interacts with ENaC and functionally regulates ENaC activity. Syntaxin 1A was able to coimmunoprecipitate in vitro-translated gamma-ENaC, but not alpha- or beta-ENaC. Also, using antibodies raised against alpha-, beta-, or gamma-ENaC, we detected syntaxin 1A in immunoprecipitates from Madin-Darby canine kidney cells stably transfected with alphabetagamma-ENaC. In bilayers, syntaxin 1A inhibited ENaC, and this syntaxin 1A modulation of ENaC activity was eliminated by truncations of cytoplasmic domains of the ENaC subunits. Our findings provide evidence for a direct physical interaction between ENaC and syntaxin 1A and suggest involvement of ENaC's cytoplasmic domains in functional modulation of ENaC activity by syntaxin 1A.
Univ. of Alabama at Birmingham, 1918 University Blvd., MCLM 704, Birmingham, AL 35294-0005, USA.
Bakhrom K
BK
Berdiev
Biljana
B
Jovov
Ward C
WC
Tucker
Anjaparavanda P
AP
Naren
Catherine M
CM
Fuller
Edwin R
ER
Chapman
Dale J
DJ
Benos
D000818:Animals; D000954:Antigens, Surface / Q000502:physiology*; D015153:Blotting, Western; D002460:Cell Line; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D004594:Electrophysiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D053503:Epithelial Sodium Channels; D007150:Immunohistochemistry; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008051:Lipid Bilayers; D009419:Nerve Tissue Proteins / Q000502:physiology*; D011233:Precipitin Tests; D014176:Protein Biosynthesis / Q000235:genetics; D018075:RNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D050827:Syntaxin 1; D014158:Transcription, Genetic; D014162:Transfection
D000954:Antigens, Surface; D053503:Epithelial Sodium Channels; D008051:Lipid Bilayers; D009419:Nerve Tissue Proteins; D018075:RNA, Complementary; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D050827:Syntaxin 1