Shear force sensing of epithelial Na⁺ channel (ENaC) relies on N-glycosylated asparagines in the palm and knuckle domains of αENaC

Mechanosensitive ion channels are crucial for normal cell function and facilitate physiological function, such as blood pressure regulation. So far little is known about the molecular mechanisms of how channels sense mechanical force. Canonical vertebrate epithelial Na⁺ channel (ENaC) formed by α-,...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2020-01, Vol.117 (1), p.717-726
Main Authors: Knoepp, Fenja, Ashley, Zoe, Barth, Daniel, Baldin, Jan-Peter, Jennings, Michael, Kazantseva, Marina, Saw, Eng Leng, Katare, Rajesh, de la Rosa, Diego Alvarez, Weissmann, Norbert, Fronius, Martin
Format: Article
Language:English
Subjects:
Animals
Asparagine - chemistry
Asparagine - metabolism
Biological Sciences
Blood pressure
Degenerin
Disease Models, Animal
Domains
Electrolytic cells
Endothelial Cells
Endothelium, Vascular - cytology
Endothelium, Vascular - pathology
Endothelium, Vascular - physiopathology
Epithelial cells
Epithelial Sodium Channels - chemistry
Epithelial Sodium Channels - genetics
Epithelial Sodium Channels - metabolism
Extracellular matrix
Extracellular Matrix - metabolism
Female
Glycosylation
HEK293 Cells
Homeostasis
Humans
Hypertension
Hypertension - etiology
Hypertension - pathology
Hypertension - physiopathology
Ion channels
Male
Mice
Mice, Transgenic
Molecular modelling
Mutagenesis, Site-Directed
N-glycans
Oocytes
Patch-Clamp Techniques
Point Mutation
Polysaccharides
Polysaccharides - chemistry
Protein Domains - genetics
Shear forces
Sodium
Stress, Mechanical
Tethers
Vertebrates
Xenopus laevis
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Summary:Mechanosensitive ion channels are crucial for normal cell function and facilitate physiological function, such as blood pressure regulation. So far little is known about the molecular mechanisms of how channels sense mechanical force. Canonical vertebrate epithelial Na⁺ channel (ENaC) formed by α-, β-, and γ-subunits is a shear force (SF) sensor and a member of the ENaC/degenerin protein family. ENaC activity in epithelial cells contributes to electrolyte/fluid-homeostasis and blood pressure regulation. Furthermore, ENaC in endothelial cells mediates vascular responsiveness to regulate blood pressure. Here, we provide evidence that ENaC’s ability to mediate SF responsiveness relies on the “force-from-filament” principle involving extracellular tethers and the extracellular matrix (ECM). Two glycosylated asparagines, respectively their N-glycans localized in the palm and knuckle domains of αENaC, were identified as potential tethers. Decreased SF-induced ENaC currents were observed following removal of the ECM/glycocalyx, replacement of these glycosylated asparagines, or removal of N-glycans. Endothelial-specific overexpression of αENaC in mice induced hypertension. In contrast, expression of αENaC lacking these glycosylated asparagines blunted this effect. In summary, glycosylated asparagines in the palm and knuckle domains of αENaC are important for SF sensing. In accordance with the force-from-filament principle, they may provide a connection to the ECM that facilitates vascular responsiveness contributing to blood pressure regulation.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1911243117