Merta Holly, Gov Kaitlynn, Isogai Tadamoto, Paul Blessy, Sannigrahi Achinta, Radhakrishnan Arun, Danuser Gaudenz, Henne W Mike
Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
Lyda Hill Department of Bioinformatics and Cecil H. and Ida Green Center for Systems Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
Cell Rep. 2025 Apr 22;44(4):115502. doi: 10.1016/j.celrep.2025.115502. Epub 2025 Apr 3.
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 knockin technologies, we map the proteomic landscape of the human ER network. Sub-organelle proteomics reveals enrichments of proteins into ER tubules, sheets, and the 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. Mechanistically, we find that CLMN depletion perturbs adhesion disassembly, actin dynamics, and cell movement. CLMN-depleted cells display decreased polarization of ER-plasma membrane contacts and calcium signaling factor STIM1 and altered calcium signaling near ER-actin interfaces, suggesting that CLMN influences calcium signaling to facilitate F-actin/adhesion dynamics. 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内组织尚不完全清楚。利用基于TurboID的邻近标记和CRISPR敲入技术，我们绘制了人类内质网网络的蛋白质组图谱。亚细胞器蛋白质组学揭示了蛋白质在内质网小管、片层和核膜中的富集情况。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，定位于内质网小管附近的粘着斑。从机制上讲，我们发现CLMN的缺失会扰乱粘着斑的解体、肌动蛋白动力学和细胞运动。CLMN缺失的细胞显示内质网-质膜接触以及钙信号因子STIM1的极化降低，并且在内质网-肌动蛋白界面附近的钙信号发生改变，这表明CLMN影响钙信号以促进F-肌动蛋白/粘着斑动力学。总体而言，我们绘制了内质网的亚细胞器蛋白质组图谱，将CLMN鉴定为内质网-肌动蛋白连接蛋白，并描述了一种非经典机制，通过该机制内质网小管与肌动蛋白相互作用以调节细胞迁移。
