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AMPK regulates the vacuolar proton‐ATPase via 14‐3‐3 proteins (1109.11)
Author(s) -
Albataineh Mohammad,
Gong Fan,
Li Hui,
Marciszyn Allison,
Bhalla Vivek,
Hallows Kenneth,
PastorSoler Núria
Publication year - 2014
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.28.1_supplement.1109.11
Subject(s) - ampk , protein subunit , ubiquitin , v atpase , atpase , microbiology and biotechnology , gamma subunit , protein kinase a , chemistry , activator (genetics) , phosphorylation , intercalated cell , cytoplasm , transport protein , biochemistry , biology , cell , enzyme , receptor , gene
The vacuolar proton‐ATPase (V‐ATPase) mediates proton transport across membranes. The V‐ATPase is expressed at the apical membrane of kidney type A collecting duct intercalated cells (ICs). Defects in the V‐ATPase may cause renal tubular acidosis with kidney and systemic complications. In a cell line of IC origin, Clone C cells, we showed that the V‐ATPase A subunit is phosphorylated directly by AMPK at Ser‐384. In addition, AMPK activators induced an acute cytoplasmic redistribution of the V‐ATPase in ICs. AMPK regulates transport proteins by promoting their ubiquitination and degradation, mechanisms that are likely important for inhibition of membrane transport during cellular metabolic stress. We have shown that Ser‐384 is necessary for the AMPK‐mediated cytoplasmic redistribution of the pump. It has been previously shown that the V‐ATPase A subunit binds to 14‐3‐3 proteins (14‐3‐3s), and we noticed that Ser‐384 exists within a ‘mode 1’ 14‐3‐3 binding motif. Dimeric 14‐3‐3s bind to phosphorylated sites on target proteins and thereby modulate protein‐protein interactions. We thus hypothesized that AMPK may promote V‐ATPase A subunit ubiquitination as well as increased binding to 14‐3‐3s. We detected increased coimmunoprecipitation of 14‐3‐3s to FLAG‐tagged A subunit expressed in Clone C ICs treated with the AMPK activator AICAR as compared with untreated cells. Furthermore, AICAR‐treated Clone C ICs had greater A subunit ubiquitination than untreated cells. We propose that A subunit 14‐3‐3 binding and ubiquitination are mediated by AMPK‐dependent Ser‐384 phosphorylation, thus linking regulation of the VATPase to AMPK during metabolic depletion in ICs. Grant Funding Source : Supported by NIH/NIDDK