Duncan Emily D, Han Ke-Jun, Trout Margaret A, Prekeris Rytis
Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO.
J Cell Biol. 2022 Apr 4;221(4). doi: 10.1083/jcb.202107114. Epub 2022 Mar 16.
Cell migration is a complex process that involves coordinated changes in membrane transport and actin cytoskeleton dynamics. Ras-like small monomeric GTPases, such as Rap2, play a key role in regulating actin cytoskeleton dynamics and cell adhesions. However, how Rap2 function, localization, and activation are regulated during cell migration is not fully understood. We previously identified the small GTPase Rab40b as a regulator of breast cancer cell migration. Rab40b contains a suppressor of cytokine signaling (SOCS) box, which facilitates binding to Cullin5, a known E3 ubiquitin ligase component responsible for protein ubiquitylation. In this study, we show that the Rab40b/Cullin5 complex ubiquitylates Rap2. Importantly, we demonstrate that ubiquitylation regulates Rap2 activation as well as recycling of Rap2 from the endolysosomal compartment to the lamellipodia of migrating breast cancer cells. Based on these data, we propose that Rab40b/Cullin5 ubiquitylates and regulates Rap2-dependent actin dynamics at the leading edge, a process that is required for breast cancer cell migration and invasion.
细胞迁移是一个复杂的过程，涉及膜运输和肌动蛋白细胞骨架动力学的协调变化。Ras样小单体GTP酶，如Rap2，在调节肌动蛋白细胞骨架动力学和细胞黏附中起关键作用。然而，在细胞迁移过程中，Rap2的功能、定位和激活是如何被调控的，目前尚未完全清楚。我们之前鉴定出小GTP酶Rab40b是乳腺癌细胞迁移的一个调节因子。Rab40b含有细胞因子信号抑制因子（SOCS）盒，这有助于其与Cullin5结合，Cullin5是一种已知的负责蛋白质泛素化的E3泛素连接酶成分。在本研究中，我们表明Rab40b/Cullin5复合物使Rap2泛素化。重要的是，我们证明泛素化调节Rap2的激活以及Rap2从内溶酶体区室循环至迁移乳腺癌细胞的片状伪足。基于这些数据，我们提出Rab40b/Cullin5在前沿使Rap2泛素化并调节依赖Rap2的肌动蛋白动力学，这一过程是乳腺癌细胞迁移和侵袭所必需的。
