Departments of Pharmacology, CINVESTAV-IPN, Mexico City, Mexico.
Departments of Cell Biology, CINVESTAV-IPN, Mexico City, Mexico.
Biochem Biophys Res Commun. 2020 Mar 26;524(1):109-116. doi: 10.1016/j.bbrc.2020.01.068. Epub 2020 Jan 21.
Endothelial cell sprouting is a critical event in tumor-induced angiogenesis. In melanoma and lung cancer murine models, targeting RhoJ prevents endothelial sprouting, tumor growth and metastasis and enhances the effects of conventional anti-neoplastic therapy. Aiming to understand how RhoJ is activated, we used a gain of function approach to identify constitutively active Rho guanine nucleotide exchange factors (RhoGEFs) able to promote RhoJ-dependent actin-driven membrane protrusions. We demonstrate that a membrane-anchored Intersectin 1 (ITSN1) DH-PH construct promotes endothelial cell sprouting via RhoJ. Mechanistically, this is controlled by direct interaction between the catalytic ITSN1 DH-PH module and RhoJ, it is sensitive to phosphorylation by focal adhesion kinase (FAK) and to endosomal trapping of the ITSN1 construct by dominant negative RhoJ. This ITSN1/RhoJ signaling axis is independent of Cdc42, a previously characterized ITSN1 target and a RhoJ close homologue. In conclusion, our results elucidate an ITSN1/RhoJ molecular link able to promote endothelial cell sprouting and set the basis to explore this signaling pathway in the context of tumor-induced angiogenesis.
内皮细胞发芽是肿瘤诱导血管生成中的一个关键事件。在黑色素瘤和肺癌的小鼠模型中，靶向 RhoJ 可阻止内皮细胞发芽、肿瘤生长和转移，并增强传统抗肿瘤治疗的效果。为了了解 RhoJ 是如何被激活的，我们使用了一种功能获得的方法来识别能够促进 RhoJ 依赖性肌动蛋白驱动的细胞膜突起的组成性激活的 Rho 鸟嘌呤核苷酸交换因子（RhoGEFs）。我们证明了一种膜锚定的衔接蛋白 1（ITSN1）DH-PH 结构能够通过 RhoJ 促进内皮细胞发芽。从机制上讲，这是由 ITSN1 DH-PH 模块的催化结构域与 RhoJ 的直接相互作用控制的，它对粘着斑激酶（FAK）的磷酸化和显性负性 RhoJ 对 ITSN1 结构的内体捕获敏感。这个 ITSN1/RhoJ 信号轴独立于 Cdc42，Cdc42 是一个先前表征的 ITSN1 靶标和 RhoJ 的密切同源物。总之，我们的结果阐明了一个能够促进内皮细胞发芽的 ITSN1/RhoJ 分子链接，并为在肿瘤诱导的血管生成背景下探索这种信号通路奠定了基础。
