Department of Hepato-Biliary-Pancreatic Surgery and Breast Surgery, Ehime University Graduate School of Medicine, Toon, Japan.
Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Japan.
Life Sci Alliance. 2021 Jun 29;4(9). doi: 10.26508/lsa.202101095. Print 2021 Sep.
Epidermal growth factor receptor (EGFR) and human EGFR 2 (HER2) phosphorylation drives HER2-positive breast cancer cell proliferation. Enforced activation of phosphatases for those receptors could be a therapeutic option for HER2-positive breast cancers. Here, we report that degradation of an endosomal small GTPase, RhoB, by the ubiquitin ligase complex cullin-3 (CUL3)/KCTD10 is essential for both EGFR and HER2 phosphorylation in HER2-positive breast cancer cells. Using human protein arrays produced in a wheat cell-free protein synthesis system, RhoB-GTP, and protein tyrosine phosphatase receptor type H (PTPRH) were identified as interacting proteins of connector enhancer of kinase suppressor of Ras1 (CNKSR1). Mechanistically, constitutive degradation of RhoB, which is mediated by the CUL3/KCTD10 E3 complex, enabled CNKSR1 to interact with PTPRH at the plasma membrane resulting in inactivation of EGFR phosphatase activity. Depletion of CUL3 or KCTD10 led to the accumulation of RhoB-GTP at the plasma membrane followed by its interaction with CNKSR1, which released activated PTPRH from CNKSR1. This study suggests a mechanism of PTPRH activation through the exclusive binding of RhoB-GTP to CNKSR1.
表皮生长因子受体 (EGFR) 和人表皮生长因子受体 2 (HER2) 的磷酸化驱动 HER2 阳性乳腺癌细胞增殖。针对这些受体的磷酸酶的强制激活可能是 HER2 阳性乳腺癌的一种治疗选择。在这里，我们报告了泛素连接酶复合物 CUL3/KCTD10 对小 GTP 酶 RhoB 的降解对于 HER2 阳性乳腺癌细胞中 EGFR 和 HER2 的磷酸化是必不可少的。使用在小麦无细胞蛋白合成系统中产生的人蛋白芯片，鉴定出 RhoB-GTP 和蛋白酪氨酸磷酸酶受体 H（PTPRH）是连接器增强激酶抑制 Ras1（CNKSR1）的相互作用蛋白。从机制上讲，由 CUL3/KCTD10 E3 复合物介导的 RhoB 的组成性降解使 CNKSR1 能够在质膜上与 PTPRH 相互作用，从而使 EGFR 磷酸酶活性失活。CUL3 或 KCTD10 的耗竭导致 RhoB-GTP 在质膜上积累，随后与 CNKSR1 相互作用，从而将激活的 PTPRH 从 CNKSR1 中释放出来。这项研究表明了一种通过 RhoB-GTP 与 CNKSR1 的特有结合来激活 PTPRH 的机制。
