Elevated intracellular Na+ and osmolarity stimulate catalytic activity of the ubiquitin ligase Nedd4-2

Proc Natl Acad Sci U S A. 2022 Jul 26;119(30):e2122495119. doi: 10.1073/pnas.2122495119. Epub 2022 Jul 18.


Regulation of catalytic activity of E3 ubiquitin ligases is critical for their cellular functions. We identified an unexpected mode of regulation of E3 catalytic activity by ions and osmolarity; enzymatic activity of the HECT family E3 Nedd4-2/Nedd4L is enhanced by increased intracellular Na+ ([Na+]i) and by hyperosmolarity. This stimulated activity is mediated by activation of p38-MAPK and is inhibited by WNKs. Moreover, protease (Furin)-mediated activation of the epithelial Na+ channel ENaC (a bona fide Nedd4-2 substrate), which leads to increased [Na+]i and osmolarity, results in enhanced Nedd4-2 catalytic activity. This enhancement is inhibited by a Furin inhibitor, by a protease-resistant ENaC mutant, or by treatment with the ENaC inhibitor amiloride. Moreover, WNK inhibition, which stimulates catalytic activity of Nedd4-2, leads to reduced levels of cell-surface ENaC and reduced channel activity. ENaC activity does not affect Nedd4-2:ENaC binding. Therefore, these results demonstrate activation of a ubiquitin ligase by Na+ and osmotic changes. Importantly, they reveal a negative feedback loop in which active ENaC leads to stimulation of catalytic activity of its own suppressor, Nedd4-2, to protect cells from excessive Na+ loading and hyperosmotic stress and to protect the animal from hypertension.

Keywords: ENaC; HECT; Nedd4L; hyperosmolarity; sodium.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalysis
  • Cations / metabolism
  • Epithelial Sodium Channels / genetics
  • Epithelial Sodium Channels / metabolism
  • Furin / metabolism
  • Nedd4 Ubiquitin Protein Ligases* / genetics
  • Nedd4 Ubiquitin Protein Ligases* / metabolism
  • Osmolar Concentration
  • Sodium* / metabolism


  • Cations
  • Epithelial Sodium Channels
  • Sodium
  • Nedd4 Ubiquitin Protein Ligases
  • Furin