NYMC Faculty Publications

Epoxyeicosatrienoic Acids (EETs) Regulate Epithelial Sodium Channel Activity by Extracellular Signal-Regulated Kinase 1/2 (ERK1/2)-Mediated Phosphorylation

Author Type(s)

Faculty

DOI

10.1074/jbc.M112.407981

Journal Title

The Journal of Biological Chemistry

First Page

5223

Last Page

5231

Document Type

Article

Publication Date

2-15-2013

Department

Pharmacology

Keywords

8, 11, 14-Eicosatrienoic Acid, Animals, Antibodies, Monoclonal, Antibodies, Monoclonal, Humanized, Antihypertensive Agents, Cetuximab, Cytochrome P-450 Enzyme System, Cytochrome P450 Family 2, Epidermal Growth Factor, Epithelial Sodium Channels, Extracellular Signal-Regulated MAP Kinases, Gene Expression Regulation, Humans, Hypertension, Kidney, Male, Mice, Models, Biological, Phosphorylation

Disciplines

Medicine and Health Sciences

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.

Link to Full Text

Share

COinS