Toronto General Research Institute, University Health Network, Toronto, Ontario, M5G 1L7, Canada.
J Cell Sci. 2010 Dec 1;123(Pt 23):4156-69. doi: 10.1242/jcs.071050.
XB130 is a newly described cytosolic adaptor protein and tyrosine kinase substrate, involved in Src- and RET/PTC-dependent signaling. Although XB130 has been cloned as a homologue of actin-filament-associated protein (AFAP-110), its potential regulation by the actin skeleton and its putative roles in cytoskeleton regulation have not been addressed. Here, we show that XB130 (in contrast to AFAP-110) exhibited robust translocation to the cell periphery in response to various stimuli (including epidermal growth factor, wounding and expression of constitutively active Rac) that elicit lamellipodium formation. In stimulated cells, XB130 localized to the lamellipodial F-actin meshwork. Genetic and pharmacological data suggest that the key trigger for XB130 recruitment is the formation of the branched F-actin itself. Structure-function analysis revealed that both the XB130 N-terminus (167 amino acids) and C-terminus (63 amino acids) harbor crucial regions for its translocation to lamellipodia, whereas the PH domains and Src-targeted tyrosines are dispensable. Importantly, in TPC1 thyroid papillary carcinoma cells, silencing endogenous XB130 decreased the rate of wound closure, inhibited matrigel invasion, reduced lamellipodial persistence and slowed down spreading. Thus, XB130 is a novel Rac- and cytoskeleton-regulated and cytoskeleton-regulating adaptor protein that exhibits high affinity to lamellipodial (branched) F-actin and impacts motility and invasiveness of tumor cells.
XB130 是一种新描述的细胞质衔接蛋白和酪氨酸激酶底物，参与 Src 和 RET/PTC 依赖性信号转导。虽然 XB130 已被克隆为肌动蛋白丝相关蛋白（AFAP-110）的同源物，但它是否受肌动蛋白骨架的调节及其在细胞骨架调节中的潜在作用尚未得到解决。在这里，我们表明 XB130（与 AFAP-110 相反）在各种刺激（包括表皮生长因子、创伤和组成性激活 Rac 的表达）下表现出强烈的向细胞边缘的易位，这些刺激引发了片状伪足的形成。在受刺激的细胞中，XB130 定位于片状伪足的 F-肌动蛋白网格。遗传和药理学数据表明，XB130 募集的关键触发因素是分支 F-肌动蛋白本身的形成。结构-功能分析表明，XB130 的 N 端（167 个氨基酸）和 C 端（63 个氨基酸）都包含其向片状伪足易位的关键区域，而 PH 结构域和Src 靶向的酪氨酸是可有可无的。重要的是，在 TPC1 甲状腺乳头状癌细胞中，沉默内源性 XB130 会降低伤口闭合的速度，抑制 Matrigel 侵袭，减少片状伪足的持久性，并减缓扩散。因此，XB130 是一种新型的 Rac 和细胞骨架调节的细胞骨架调节衔接蛋白，它对片状伪足（分支）F-肌动蛋白具有高亲和力，并影响肿瘤细胞的迁移和侵袭能力。
