Laboratory of Molecular Biology, Division of Life Science, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan.
Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
J Biochem. 2021 Apr 18;169(3):295-302. doi: 10.1093/jb/mvaa130.
Actin exists in monomeric globular (G-) and polymerized filamentous (F-) forms and the dynamics of its polymerization/depolymerization are tightly regulated in both the cytoplasm and the nucleus. Various essential functions of nuclear actin have been identified including regulation of gene expression and involvement in the repair of DNA double-strand breaks (DSB). Small G-actin-binding molecules affect F-actin formation and can be utilized for analysis and manipulation of actin in living cells. However, these G-actin-binding molecules are obtained by extraction from natural sources or through complex chemical synthesis procedures, and therefore, the generation of their derivatives for analytical tools is underdeveloped. In addition, their effects on nuclear actin cannot be separately evaluated from those on cytoplasmic actin. Previously, we have generated synthetic bicyclic peptides, consisting of two macrocyclic rings, which bind to G-actin but not to F-actin. Here, we describe the introduction of these bicyclic peptides into living cells. Furthermore, by conjugation to a nuclear localization signal (NLS), the bicyclic peptides accumulated in the nucleus. The NLS-bicyclic peptides repress the formation of nuclear F-actin, and impair transcriptional regulation and DSB repair. These observations highlight a potential role for NLS-linked bicyclic peptides in the manipulation of dynamics and functions of nuclear actin.
肌动蛋白以单体球状（G-）和聚合丝状（F-）两种形式存在，其聚合/解聚的动力学在细胞质和细胞核中都受到严格调控。已经确定了核肌动蛋白的各种基本功能，包括调节基因表达和参与 DNA 双链断裂（DSB）的修复。小分子 G-肌动蛋白结合分子影响 F-肌动蛋白的形成，可用于分析和操纵活细胞中的肌动蛋白。然而，这些 G-肌动蛋白结合分子是从天然来源提取或通过复杂的化学合成程序获得的，因此，用于分析工具的衍生物的产生还不够发达。此外，它们对核肌动蛋白的影响不能与对细胞质肌动蛋白的影响分开评估。以前，我们已经生成了由两个大环组成的合成双环肽，这些双环肽与 G-肌动蛋白结合，但不与 F-肌动蛋白结合。在这里，我们描述了这些双环肽在活细胞中的引入。此外，通过与核定位信号（NLS）缀合，双环肽在细胞核中积累。NLS-双环肽抑制核 F-肌动蛋白的形成，并损害转录调节和 DSB 修复。这些观察结果突出了 NLS 连接的双环肽在操纵核肌动蛋白动力学和功能方面的潜在作用。
