In vivo phosphorylation of the epithelial sodium channel.

The activity of the epithelial sodium channel (ENaC) in the distal nephron is regulated by an antidiuretic hormone, aldosterone, and insulin, but the molecular mechanisms that mediate these hormonal effects are mostly unknown. We have investigated whether aldosterone, insulin, or activation of protein kinases has an effect on the phosphorylation of the channel. Experiments were performed in an epithelial cell line generated by stable cotransfection of the three subunits (alpha, beta, and gamma) of ENaC. We found that beta and gamma, but not the alpha subunit, are phosphorylated in the basal state. Aldosterone, insulin, and protein kinases A and C increased phosphorylation of the beta and gamma subunits in their carboxyl termini, but none of these agents induced de novo phosphorylation of alpha subunits. Serines and threonines but not tyrosines were found to be phosphorylated. The results suggest that aldosterone, insulin, and protein kinases A and C modulate the activity of ENaC by phosphorylation of the carboxyl termini of the beta and gamma subunits.

[1]  R. Shimkets,et al.  The Activity of the Epithelial Sodium Channel Is Regulated by Clathrin-mediated Endocytosis* , 1997, The Journal of Biological Chemistry.

[2]  Jörg Stappert,et al.  β‐catenin is a target for the ubiquitin–proteasome pathway , 1997 .

[3]  H. Garty,et al.  Epithelial sodium channels: function, structure, and regulation. , 1997, Physiological reviews.

[4]  D. Benos,et al.  Protein kinase regulation of a cloned epithelial Na+ channel , 1996, The Journal of general physiology.

[5]  O. Staub,et al.  WW domains of Nedd4 bind to the proline‐rich PY motifs in the epithelial Na+ channel deleted in Liddle's syndrome. , 1996, The EMBO journal.

[6]  L. Schild,et al.  Identification of a PY motif in the epithelial Na channel subunits as a target sequence for mutations causing channel activation found in Liddle syndrome. , 1996, The EMBO journal.

[7]  L. Schild,et al.  Liddle disease caused by a missense mutation of beta subunit of the epithelial sodium channel gene. , 1996, The Journal of clinical investigation.

[8]  J C Olsen,et al.  CFTR as a cAMP-dependent regulator of sodium channels , 1995, Science.

[9]  H. Tohda,et al.  Insulin-activated amiloride-blockable nonselective cation and Na+ channels in the fetal distal lung epithelium. , 1995, General pharmacology.

[10]  T. Maniatis,et al.  NF-κB: A lesson in family values , 1995, Cell.

[11]  N. Farman,et al.  Cell-specific expression of epithelial sodium channel alpha, beta, and gamma subunits in aldosterone-responsive epithelia from the rat: localization by in situ hybridization and immunocytochemistry , 1994, The Journal of cell biology.

[12]  J. Hayslett,et al.  Mechanism of insulin-stimulated electrogenic sodium transport. , 1994, Kidney international.

[13]  M. Lazdunski,et al.  Biochemical analysis of the membrane topology of the amiloride-sensitive Na+ channel. , 1994, The Journal of biological chemistry.

[14]  K. Kokko,et al.  Inhibition of apical Na+ channels in rabbit cortical collecting tubules by basolateral prostaglandin E2 is modulated by protein kinase C. , 1992, The Journal of clinical investigation.

[15]  J. Schafer,et al.  Regulation of Na+ channels in the cortical collecting duct by AVP and mineralocorticoids. , 1992, Kidney international.