上皮钠通道 (ENaC) 的剪切力感应依赖于 αENaC 的棕榈和指节结构域中的 -糖基化天冬酰胺。

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

机构信息

Excellence-Cluster Cardio-Pulmonary Institute, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Justus-Liebig University Giessen, D-35392 Giessen, Germany.

Department of Physiology, University of Otago, 9016 Dunedin New Zealand.

出版信息

Proc Natl Acad Sci U S A. 2020 Jan 7;117(1):717-726. doi: 10.1073/pnas.1911243117. Epub 2019 Dec 23.

Abstract

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 -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 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.

摘要

机械敏感离子通道对于正常细胞功能至关重要,有助于生理功能,如血压调节。目前,关于通道如何感知机械力的分子机制知之甚少。经典的脊椎动物上皮钠通道(ENaC)由α、β和γ亚基组成,是剪切力(SF)传感器,也是 ENaC/退行蛋白家族的成员。上皮细胞中的 ENaC 活性有助于电解质/流体稳态和血压调节。此外,内皮细胞中的 ENaC 介导血管对血压的反应性。在这里,我们提供的证据表明,ENaC 介导 SF 反应性的能力依赖于涉及细胞外系绳和细胞外基质(ECM)的“力从纤维”原理。鉴定出两个糖基化天冬酰胺,分别是其位于αENaC 手掌和指节域中的-β-聚糖,作为潜在的系绳。在去除 ECM/糖萼、替换这些糖基化天冬酰胺或去除聚糖后,观察到 SF 诱导的 ENaC 电流减少。在小鼠中内皮细胞特异性过表达αENaC 会引起高血压。相比之下,表达缺乏这些糖基化天冬酰胺的αENaC 则削弱了这种作用。总之,αENaC 手掌和指节域中的糖基化天冬酰胺对于 SF 感应很重要。根据力从纤维的原理,它们可能与 ECM 建立连接,从而促进血管反应性,有助于血压调节。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/0316/6955349/1531981ef054/pnas.1911243117fig01.jpg

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