PMID- 15972388
OWN - NLM
STAT- MEDLINE
DCOM- 20051121
LR  - 20131121
IS  - 1931-857X (Print)
IS  - 1522-1466 (Linking)
VI  - 289
IP  - 5
DP  - 2005 Nov
TI  - PKA-dependent ENaC trafficking requires the SNARE-binding protein complexin.
PG  - F969-77
AB  - Acute regulation of epithelial sodium channel (ENaC) function at the apical 
      surface of polarized kidney cortical collecting duct (CCD) epithelial cells 
      occurs in large part by changes in channel number, mediated by membrane vesicle 
      trafficking. Several soluble N-ethyl-maleimide-sensitive factor attachment 
      protein receptors (SNARE) have been implicated in this process. A novel 
      SNARE-binding protein, complexin, has been identified in nervous tissue which 
      specifically binds to and stabilizes SNARE complexes at synaptic membranes to 
      promote vesicle fusion. To test whether this protein is present in mouse CCD 
      (mCCD) cells and its possible involvement in acute ENaC regulation, we cloned 
      complexin (isoform II) from a mouse kidney cDNA library. Complexin II mRNA 
      coexpressed with alpha-, beta-, and gamma-ENaC subunits in Xenopus laevis oocytes 
      reduced sodium currents to 16 +/- 3% (n = 19) of control values. Short-circuit 
      current (I(sc)) measurements on mCCD cell lines stably over- or underexpressing 
      complexin produced similar results. Basal I(sc) was reduced from 12.0 +/- 1.0 (n 
      = 15) to 2.0 +/- 0.4 (n = 15) and 1.8 +/- 0.3 (n = 17) microA/cm(2), 
      respectively. Similarly forskolin-stimulated I(sc) was reduced from control 
      values of 20.0 +/- 2 to 2.7 +/- 0.5 and 2.3 +/- 0.4 microA/cm(2) by either 
      increasing or decreasing complexin expression. Surface biotinylation demonstrated 
      that the complexin-induced reduction in basal I(sc)was due to a reduction in 
      apical membrane-resident ENaC and the inhibition in forskolin stimulation was due 
      to the lack of ENaC insertion into the apical membrane to increase surface 
      channel number. Immunofluorescent localization of SNARE proteins in polarized 
      mCCD epithelia detected the presence of syntaxins 1 and 3 and 
      synaptosomal-associated protein of 23 kDa (SNAP-23) at the apical membrane, and 
      vesicle-associated membrane protein (VAMP2) was localized to intracellular 
      compartments. These findings identify SNAREs that may mediate ENaC-containing 
      vesicle insertion in mCCD epithelia and suggest that stabilization of SNARE 
      interactions by complexin is an essential aspect of the regulated trafficking 
      events that increase apical membrane ENaC density either by constitutive or 
      regulated trafficking pathways.
FAU - Butterworth, M B
AU  - Butterworth MB
AD  - Dept. of Cell Biology and Physiology, University of Pittsburgh, PA 15261, USA. 
      michael7@pitt.edu
FAU - Frizzell, R A
AU  - Frizzell RA
FAU - Johnson, J P
AU  - Johnson JP
FAU - Peters, K W
AU  - Peters KW
FAU - Edinger, R S
AU  - Edinger RS
LA  - eng
GR  - DK-061296-03/DK/NIDDK NIH HHS/United States
GR  - R01-DK-057718/DK/NIDDK NIH HHS/United States
GR  - R01-DK-54814/DK/NIDDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
DEP - 20050621
PL  - United States
TA  - Am J Physiol Renal Physiol
JT  - American journal of physiology. Renal physiology
JID - 100901990
RN  - 0 (Adaptor Proteins, Vesicular Transport)
RN  - 0 (Epithelial Sodium Channels)
RN  - 0 (Nerve Tissue Proteins)
RN  - 0 (Sodium Channels)
RN  - 0 (complexin II)
RN  - 9NEZ333N27 (Sodium)
SB  - IM
MH  - Adaptor Proteins, Vesicular Transport
MH  - Animals
MH  - Cloning, Molecular
MH  - Epithelial Sodium Channels
MH  - Gene Library
MH  - Kidney Tubules, Collecting/*physiology
MH  - Mice
MH  - Nerve Tissue Proteins/genetics/*physiology
MH  - Oocytes
MH  - Sodium/pharmacokinetics
MH  - Sodium Channels/*physiology
MH  - Synaptic Vesicles/physiology
MH  - Xenopus laevis
EDAT- 2005/06/24 09:00
MHDA- 2005/12/13 09:00
CRDT- 2005/06/24 09:00
PHST- 2005/06/24 09:00 [pubmed]
PHST- 2005/12/13 09:00 [medline]
PHST- 2005/06/24 09:00 [entrez]
AID - 00390.2003 [pii]
AID - 10.1152/ajprenal.00390.2003 [doi]
PST - ppublish
SO  - Am J Physiol Renal Physiol. 2005 Nov;289(5):F969-77. doi: 
      10.1152/ajprenal.00390.2003. Epub 2005 Jun 21.