Glycosylation-dependent activation of epithelial sodium channel by solnatide

Waheed Shabbir, Susan Tzotzos, Minela Bedak, Mohammad Aufy, Anita Willam, Martin Kraihammer, Alexander Holzner, Istvan Czikora, Parastoo Scherbaum-Hazemi, Hendrik Fischer, Helmut Pietschmann, Bernhard Fischer, Rudolf Lucas, Rosa Lemmens-Gruber

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Dysfunction of the epithelial sodium channel (ENaC), which regulates salt and water homeostasis in epithelia, causes several human pathological conditions, including pulmonary oedema. This is a potentially lethal complication of acute lung injury at least partially caused by dysfunctional alveolar liquid clearance, which in turn impairs alveolar gas exchange. Solnatide (named TIP-peptide, AP301), a 17 residue peptide mimicking the lectin-like domain of TNF has been shown to activate ENaC in several experimental animal models of acute lung injury and is being evaluated as a potential therapy for pulmonary oedema. The peptide has recently completed phase 1 and 2a clinical trials. In this study, we identify a glycosylation-dependent mechanism that preserves ENaC function and expression. Since our previous data suggested that the pore-forming subunits of ENaC are essential for maximal current activation by solnatide, we performed single- and multi-N-glycosylation site mutations in αN232,293,312,397,511Q- and δN166,211,384Q-subunits, in order to identify crucial residues for interaction with solnatide within the extracellular loop of the channel. Additionally, we generated αL576X and αN232,293,312,397,511Q,L576X deletion mutants of ENaC-α, since we have previously demonstrated that the carboxy terminal domain of this subunit is also involved in its interaction with solnatide. In cells expressing αN232,293,312,397,511Q,L576Xβγ-hENaC or δN166,311,384Q,D552Xβγ-hENaC activation by solnatide, as measured in whole cell patch clamp mode, was completely abolished, whereas it was attenuated in αL576Xβγ-hENaC- and δD552Xβγ-hENaC-expressing cells. Taken together, our findings delineate an N-glycan dependent interaction between the TIP-peptide and ENaC leading to normalization of both sodium and fluid absorption in oedematous alveoli to non-oedematous levels.

Original languageEnglish (US)
Pages (from-to)740-753
Number of pages14
JournalBiochemical Pharmacology
Volume98
Issue number4
DOIs
StatePublished - Dec 15 2015

Keywords

  • Epithelial sodium channel (ENaC)
  • Glycosylation
  • Patch-clamp
  • Western blot

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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  • Cite this

    Shabbir, W., Tzotzos, S., Bedak, M., Aufy, M., Willam, A., Kraihammer, M., Holzner, A., Czikora, I., Scherbaum-Hazemi, P., Fischer, H., Pietschmann, H., Fischer, B., Lucas, R., & Lemmens-Gruber, R. (2015). Glycosylation-dependent activation of epithelial sodium channel by solnatide. Biochemical Pharmacology, 98(4), 740-753. https://doi.org/10.1016/j.bcp.2015.08.003