title: Epoxyeicosatrienoic acids (EETs) regulate epithelial sodium channel activity by extracellular signal-regulated kinase 1/2 (ERK1/2)-mediated phosphorylation.
abstract: The epithelial sodium channel (ENaC) participates in the regulation of plasma sodium and volume, and gain of function mutations in the human channel cause salt-sensitive hypertension. Roles for the arachidonic acid epoxygenase metabolites, the epoxyeicosatrienoic acids (EETs), in ENaC activity have been identified; however, their mechanisms of action remain unknown. In polarized M1 cells, 14,15-EET inhibited amiloride-sensitive apical to basolateral sodium transport as effectively as epidermal growth factor (EGF). The EET effects were associated with increased threonine phosphorylation of the ENaC β and γ subunits and abolished by inhibitors of (a) mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/extracellular signal regulated kinases 1 and 2 (MEK/ERK1/2) and (b) EGF receptor signaling. CYP2C44 epoxygenase knockdown blunted the sodium transport effects of EGF, and its 14,15-EET metabolite rescued the knockdown phenotype. The relevance of these findings is indicated by (a) the hypertension that results in mice administered cetuximab, an inhibitor of EGF receptor binding, and (b) immunological data showing an association between the pressure effects of cetuximab and reductions in ENaCγ phosphorylation. These studies (a) identify an ERK1/2-dependent mechanism for ENaC inhibition by 14,15-EET, (b) point to ENaC as a proximal target for EET-activated ERK1/2 mitogenic kinases, (c) characterize a mechanistic commonality between EGF and epoxygenase metabolites as ENaC inhibitors, and (d) suggest a CYP2C epoxygenase-mediated pathway for the regulation of distal sodium transport.
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232, USA.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Pidkovka
authors.forename: Reena
authors.initials: R
authors.lastname: Rao
authors.forename: Shaojun
authors.initials: S
authors.lastname: Mei
authors.forename: Yan
authors.initials: Y
authors.lastname: Gong
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Harris
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Wang
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Capdevila
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000959:Antihypertensive Agents / Q000494:pharmacology; D000068818:Cetuximab; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D000072467:Cytochrome P450 Family 2; D004815:Epidermal Growth Factor / Q000378:metabolism; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D006973:Hypertension; D007668:Kidney / Q000378:metabolism; D008297:Male; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000959:Antihypertensive Agents; D053503:Epithelial Sodium Channels; D004815:Epidermal Growth Factor; C046782:14,15-epoxy-5,8,11-eicosatrienoic acid; D003577:Cytochrome P-450 Enzyme System; C492667:Cyp2c23 protein, mouse; D000072467:Cytochrome P450 Family 2; D048049:Extracellular Signal-Regulated MAP Kinases; D015126:8,11,14-Eicosatrienoic Acid; D000068818:Cetuximab