Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO.
Proteomics Center, Institute of Biochemistry, Vilnius University Life Sciences Center, Vilnius, Lithuania.
J Cell Biol. 2021 Jul 5;220(7). doi: 10.1083/jcb.202008060. Epub 2021 May 17.
Rab40b is a SOCS box-containing protein that regulates the secretion of MMPs to facilitate extracellular matrix remodeling during cell migration. Here, we show that Rab40b interacts with Cullin5 via the Rab40b SOCS domain. We demonstrate that loss of Rab40b-Cullin5 binding decreases cell motility and invasive potential and show that defective cell migration and invasion stem from alteration to the actin cytoskeleton, leading to decreased invadopodia formation, decreased actin dynamics at the leading edge, and an increase in stress fibers. We also show that these stress fibers anchor at less dynamic, more stable focal adhesions. Mechanistically, changes in the cytoskeleton and focal adhesion dynamics are mediated in part by EPLIN, which we demonstrate to be a binding partner of Rab40b and a target for Rab40b-Cullin5-dependent localized ubiquitylation and degradation. Thus, we propose a model where Rab40b-Cullin5-dependent ubiquitylation regulates EPLIN localization to promote cell migration and invasion by altering focal adhesion and cytoskeletal dynamics.
Rab40b 是一种含有 SOCS 盒的蛋白质，可调节 MMPs 的分泌，从而促进细胞迁移过程中细胞外基质的重塑。在这里，我们表明 Rab40b 通过 Rab40b SOCS 结构域与 Cullin5 相互作用。我们证明了 Rab40b-Cullin5 结合的缺失会降低细胞迁移和侵袭能力，并表明缺陷细胞迁移和侵袭源自肌动蛋白细胞骨架的改变，导致侵袭伪足形成减少、前缘处的肌动蛋白动力学降低以及应力纤维增加。我们还表明，这些应力纤维锚定在动态性较低、稳定性较高的焦点黏附处。在机制上，细胞骨架和焦点黏附动力学的变化部分由 EPLIN 介导，我们证明 EPLIN 是 Rab40b 的结合伙伴，也是 Rab40b-Cullin5 依赖性局部泛素化和降解的靶标。因此，我们提出了一个模型，其中 Rab40b-Cullin5 依赖性泛素化调节 EPLIN 的定位，通过改变焦点黏附和细胞骨架动力学来促进细胞迁移和侵袭。
