RNA. 2014 May;20(5):689-701. doi: 10.1261/rna.043208.113. Epub 2014 Mar 28.
Epithelial cell-cell contact stimulates actin cytoskeleton remodeling to down-regulate branched filament polymerization-driven lamellar protrusion and subsequently to assemble linear actin filaments required for E-cadherin anchoring during adherens junction complex assembly. In this manuscript, we demonstrate that de novo protein synthesis, the β-actin 3' UTR, and the β-actin mRNA zipcode are required for epithelial adherens junction complex assembly but not maintenance. Specifically, we demonstrate that perturbing cell-cell contact-localized β-actin monomer synthesis causes epithelial adherens junction assembly defects. Consequently, inhibiting β-actin mRNA zipcode/ZBP1 interactions with β-actin mRNA zipcode antisense oligonucleotides, to intentionally delocalize β-actin monomer synthesis, is sufficient to perturb adherens junction assembly following epithelial cell-cell contact. Additionally, we demonstrate active RhoA, the signal required to drive zipcode-mediated β-actin mRNA targeting, is localized at epithelial cell-cell contact sites in a β-actin mRNA zipcode-dependent manner. Moreover, chemically inhibiting Src kinase activity prevents the local stimulation of β-actin monomer synthesis at cell-cell contact sites while inhibiting epithelial adherens junction assembly. Together, these data demonstrate that epithelial cell-cell contact stimulates β-actin mRNA zipcode-mediated monomer synthesis to spatially regulate actin filament remodeling, thereby controlling adherens junction assembly to modulate cell and tissue adhesion.
上皮细胞-细胞接触刺激肌动蛋白细胞骨架重塑，下调分支丝状聚合驱动的板层突起，随后组装线性肌动蛋白丝，这是细胞黏附连接复合体组装过程中 E-钙黏蛋白锚定所必需的。在本手稿中，我们证明了新蛋白合成、β-肌动蛋白 3'UTR 和β-肌动蛋白 mRNA 拉链区对于上皮细胞黏附连接复合体的组装是必需的，但不是维持所必需的。具体来说，我们证明了扰乱细胞-细胞接触定位的β-肌动蛋白单体合成会导致上皮细胞黏附连接组装缺陷。因此，抑制β-肌动蛋白 mRNA 拉链区/ZBP1 与β-肌动蛋白 mRNA 拉链区反义寡核苷酸的相互作用，故意使β-肌动蛋白单体合成定位，足以在细胞-细胞接触后扰乱黏附连接的组装。此外，我们证明了活性 RhoA（驱动 zipcode 介导的β-肌动蛋白 mRNA 靶向所需的信号）以β-肌动蛋白 mRNA 拉链区依赖的方式定位在上皮细胞-细胞接触部位。此外，化学抑制Src 激酶活性可防止在细胞-细胞接触部位局部刺激β-肌动蛋白单体合成，同时抑制上皮细胞黏附连接的组装。综上所述，这些数据表明，上皮细胞-细胞接触刺激β-肌动蛋白 mRNA 拉链区介导的单体合成，以空间调节肌动蛋白丝重塑，从而控制黏附连接的组装以调节细胞和组织黏附。
