Shear force sensing of epithelial Na+ channel (ENaC) relies on N-glycosylated asparagines in the palm and knuckle domains of αENaC
Shear force sensing of epithelial Na+ channel (ENaC) relies on N-glycosylated asparagines in the palm and knuckle domains of αENaC
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DOI：
10.1073/pnas.1911243117
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发表时间：
2020-01-07
影响因子：
11.1
通讯作者：
Fronius, Martin
中科院分区：
文献类型：
--
作者：
Knoepp, Fenja;Ashley, Zoe;Fronius, Martin
机械敏感性离子通道对于正常细胞功能至关重要，并促进生理功能，如血压调节。到目前为止，人们对通道如何感知机械力的分子机制知之甚少。典型脊椎动物上皮Na+通道（ENaC）由α-、β-和γ-亚基形成，是剪切力（SF）传感器，并且是ENaC/变性蛋白家族的成员。上皮细胞中的ENaC活性有助于电解质/液体稳态和血压调节。此外，内皮细胞中的ENaC介导血管反应性以调节血压。在这里，我们提供的证据表明，ENaC的能力，介导SF的反应依赖于“力从丝”的原则，涉及细胞外拴系和细胞外基质（ECM）。两个糖基化天冬酰胺，分别位于α ENaC的手掌和关节结构域的N-聚糖，被鉴定为潜在的系链。在去除ECM/糖萼、替换这些糖基化天冬酰胺或去除N-聚糖后，观察到SF诱导的ENaC电流降低。在小鼠诱导的高血压中内皮特异性α ENaC过表达。相反，缺乏这些糖基化天冬酰胺的α ENaC的表达减弱了这种作用。总之，α ENaC的手掌和关节结构域中的糖基化天冬酰胺对于SF传感是重要的。根据细丝产生力的原理，它们可以提供与ECM的连接，从而促进有助于血压调节的血管反应性。
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 alpha-, beta-, and gamma-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 alpha ENaC, 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 alpha ENaC in mice induced hypertension. In contrast, expression of alpha ENaC lacking these glycosylated asparagines blunted this effect. In summary, glycosylated asparagines in the palm and knuckle domains of alpha ENaC 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.