Pulmonary oedema is a life threatening condition, caused by acute lung injury. Although failure of gas exchange in the alveolar spaces causes most of the morbidity and mortality, it remained uncertain how and when epithelial sodium channels (ENaC) loose their liquid clearance ability. AP301, a lectin-like domain derived peptide of TNF-α, increases amiloride-sensitive current in A549 cells as well as in heterologously expressed hENaC, an effect which was lost after membrane deglycosylation (1). Consequently, the present study was undertaken to determine the interaction of AP301 with hENaC glycosylation sites. To analyze the effect of N-linked glycosylation in hα-ENaC, we substituted asparagine to glutamine. AP301-induced increase in sodium current in different subunit compositions was studied in patch-clamp assays.Indeed, AP301 weakly activated single as well as multiple asparagine mutants of α-hENaC. These findings suggest that specific interaction of AP301 ENaC requires precedent binding to glycosylated extracellular loop and pore-forming ∝- or δ-delta subunits.
Physiology 2014 (London, UK) (2014) Proc Physiol Soc 31, PCB088
Poster Communications: Glycosylation-dependent lectin-receptor interaction stimulates inward sodium current in epithelial sodium channels
W. Shabbir1, M. Hasanovic1, A. Willam1, S. Tzotzo2, H. Fischer2, H. Pietschmann2, B. Fischer2, R. Lucas3, R. Lemmens-Gruber1
1. Pharmacology and Toxicology, Univesity of Vienna, Vienna, Austria. 2. R&D, APEPTICO GmbH, Vienna, Austria. 3. Vascular Biology Center,, Medical College of Georgia, Georgia, Georgia, United States.
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