Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016, China; Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016, China.
Laboratory of Reproductive Biology, Chongqing Medical University, Chongqing 400016, China.
J Biol Chem. 2020 Apr 17;295(16):5335-5349. doi: 10.1074/jbc.RA119.012260. Epub 2020 Mar 13.
The actin cytoskeleton is extremely dynamic and supports diverse cellular functions in many physiological and pathological processes, including tumorigenesis. However, the mechanisms that regulate the actin-related protein 2/3 (ARP2/3) complex and thereby promote actin polymerization and organization in cancer cells are not well-understood. We previously implicated the proline-rich 11 (PRR11) protein in lung cancer development. In this study, using immunofluorescence staining, actin polymerization assays, and siRNA-mediated gene silencing, we uncovered that cytoplasmic PRR11 is involved in F-actin polymerization and organization. We found that dysregulation of PRR11 expression results in F-actin rearrangement and nuclear instability in non-small cell lung cancer cells. Results from molecular mechanistic experiments indicated that PRR11 associates with and recruits the ARP2/3 complex, facilitates F-actin polymerization, and thereby disrupts the F-actin cytoskeleton, leading to abnormal nuclear lamina assembly and chromatin reorganization. Inhibition of the ARP2/3 complex activity abolished irregular F-actin polymerization, lamina assembly, and chromatin reorganization due to PRR11 overexpression. Notably, experiments with truncated PRR11 variants revealed that PRR11 regulates F-actin through different regions. We found that deletion of either the N or C terminus of PRR11 abrogates its effects on F-actin polymerization and nuclear instability and that deletion of amino acid residues 100-184 or 100-200 strongly induces an F-actin structure called the actin comet tail, not observed with WT PRR11. Our findings indicate that cytoplasmic PRR11 plays an essential role in regulating F-actin assembly and nuclear stability by recruiting the ARP2/3 complex in human non-small cell lung carcinoma cells.
肌动蛋白细胞骨架极其动态，并在多种生理和病理过程中支持多种细胞功能，包括肿瘤发生。然而，调节肌动蛋白相关蛋白 2/3 (ARP2/3) 复合物的机制以及从而促进癌细胞中肌动蛋白聚合和组织的机制尚不清楚。我们之前在肺癌发生中涉及富含脯氨酸 11 (PRR11) 蛋白。在这项研究中，我们使用免疫荧光染色、肌动蛋白聚合测定和 siRNA 介导的基因沉默，揭示细胞质 PRR11 参与 F-肌动蛋白聚合和组织。我们发现 PRR11 表达失调导致非小细胞肺癌细胞中 F-肌动蛋白重排和核不稳定。分子机制实验的结果表明，PRR11 与 ARP2/3 复合物结合并募集它，促进 F-肌动蛋白聚合，从而破坏 F-肌动蛋白细胞骨架，导致异常核层组装和染色质重排。ARP2/3 复合物活性的抑制消除了由于 PRR11 过表达导致的不规则 F-肌动蛋白聚合、层组装和染色质重排。值得注意的是，使用截断的 PRR11 变体的实验表明，PRR11 通过不同区域调节 F-肌动蛋白。我们发现，PRR11 的 N 或 C 末端的缺失消除了其对 F-肌动蛋白聚合和核不稳定的影响，并且缺失氨基酸残基 100-184 或 100-200 强烈诱导称为肌动蛋白彗星尾的 F-肌动蛋白结构，而不是用 WT PRR11 观察到的结构。我们的研究结果表明，细胞质 PRR11 通过在人非小细胞肺癌细胞中募集 ARP2/3 复合物，在调节 F-肌动蛋白组装和核稳定性方面发挥重要作用。
