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Annexin II light chain p11 interacts with ENaC to increase functional activity at the membrane
Author(s) -
McDonald Cowles Fiona J.,
Cheung Tanya T.,
Ismail Noor AS.,
Moir Rachel,
Arora Nikhil,
Condliffe Steven
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.624.8
Subject(s) - epithelial sodium channel , chemistry , apical membrane , microbiology and biotechnology , amiloride , gene knockdown , annexin a2 , exocytosis , annexin , biology , cell , biochemistry , secretion , sodium , membrane , apoptosis , organic chemistry
The epithelial Na + channel (ENaC) provides for Na + absorption in various types of epithelia including the kidney, lung and colon where ENaC is localized to the apical membrane to enable Na + entry into the cell. The degree of Na + entry via ENaC largely depends on the number of active channels localized to the cell membrane. While regulation of ENaC endocytosis has been well studied, relatively little is understood of the proteins that govern ENaC exocytosis. We hypothesized that the annexin II light chain, p11 could participate in the transport of ENaC along the exocytic pathway. Our results demonstrate that all three ENaC channel subunits interacted with p11 in an in vitro binding assay. Quantitative mass spectrometry of affinity‐purified ENaC‐p11 complexes recovered several other trafficking proteins including HSP‐90, COMMD10 and annexin A6. We also found that p11 exhibits a robust protein expression in cortical collecting duct epithelial cells. However, the expression of p11 in these cells was not influenced by either short‐term or long‐term exposure to aldosterone. To determine whether the p11 interaction affected ENaC function, we measured amiloride sensitive Na + currents in Xenopus oocytes or mammalian epithelia coexpressing ENaC and p11, or a siRNA to p11. Results from these experiments showed that p11 significantly augmented amiloride‐sensitive current, whereas knockdown of p11 decreased current. Further, knockdown of p11 reduced the ENaC cell surface population suggesting p11 promotes membrane insertion of ENaC. Overall, our findings reveal a novel protein‐protein interaction of p11 with ENaC that controls the number of ENaC channels inserted at the plasma membrane via the exocytic pathway. Support or Funding Information This work was supported by a University of Otago Research Grant, and an AIM grant from the Department of Physiology, University of Otago. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .