Merta Holly, Isogai Tadamoto, Paul Blessy, Danuser Gaudenz, Henne W Mike
Department of Cell Biology, UT Southwestern Medical Center, Dallas TX 75390.
Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, UT Southwestern Medical Center, Dallas TX 75390.
bioRxiv. 2024 Jan 25:2024.01.24.577043. doi: 10.1101/2024.01.24.577043.
The endoplasmic reticulum (ER) is structurally and functionally diverse, yet how its functions are organized within morphological subdomains is incompletely understood. Utilizing TurboID-based proximity labeling and CRISPR knock-in technologies, here we map the proteomic landscape of the human ER and nuclear envelope. Spatial proteomics reveals enrichments of proteins into ER tubules, sheets, and nuclear envelope. We uncover an ER-enriched actin-binding protein, Calmin (CLMN), and define it as an ER-actin tether that localizes to focal adhesions adjacent to ER tubules. CLMN depletion perturbs focal adhesion disassembly, actin dynamics, and cell movement. Mechanistically, CLMN-depleted cells also exhibit defects in calcium signaling near ER-actin interfaces, suggesting CLMN promotes calcium signaling near adhesions to facilitate their disassembly. Collectively, we map the sub-organelle proteome landscape of the ER, identify CLMN as an ER-actin tether, and describe a non-canonical mechanism by which ER tubules engage actin to regulate cell migration.
内质网（ER）在结构和功能上具有多样性，然而其功能如何在形态学亚结构域中组织尚不完全清楚。利用基于TurboID的邻近标记和CRISPR基因敲入技术，我们绘制了人类内质网和核膜的蛋白质组图谱。空间蛋白质组学揭示了蛋白质在内质网管、内质网片层和核膜中的富集。我们发现了一种在内质网中富集的肌动蛋白结合蛋白，钙调素（CLMN），并将其定义为一种内质网-肌动蛋白连接蛋白，定位于内质网管附近的粘着斑。CLMN的缺失扰乱了粘着斑的解体、肌动蛋白动力学和细胞运动。从机制上讲，CLMN缺失的细胞在内质网-肌动蛋白界面附近的钙信号传导中也表现出缺陷，这表明CLMN促进粘着斑附近的钙信号传导以促进其解体。总的来说，我们绘制了内质网的亚细胞器蛋白质组图谱，确定CLMN为内质网-肌动蛋白连接蛋白，并描述了一种非经典机制，通过该机制内质网管与肌动蛋白相互作用以调节细胞迁移。
