Xu Linlin, Guo Jiankun, Xie Xinsheng, Wang Hailong, Jiang Alan, Huang Changhua, Yang Hua, Luo Shiwen, Chen Limin
Medical Innovation Center, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, 330006, Jiangxi, China.
Department of Pathology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, 330006, Jiangxi, China.
Cell Death Discov. 2025 Feb 1;11(1):38. doi: 10.1038/s41420-025-02317-y.
Small GTPases play a critical role as regulatory molecules in signaling transduction and various cellular processes, contributing to the development of human diseases, including cancers. GPN3, an evolutionarily conserved member of the GPN-loop GTPase subfamily classified in 2007 according to its structure, has limited knowledge regarding its cellular functions and molecular mechanisms. In this study, we demonstrate that GPN3 interacts with clathrin light chain A (CLTA), a vesicle coat protein, as well as clathrin-mediated endocytosis associated modulators AP2B1 and AP2S1. Upregulation of GPN3 leads to the inhibition of clathrin-coated pit invagination. Furthermore, we discovered that GPN3 interacts with the epidermal growth factor receptor (EGFR) and regulates the co-localization of EGFR and CLTA, as well as the localization of EGFR in early endosomes upon EGF stimulation. As a result, this leads to a decrease in endocytic levels of EGFR and an increase in the accumulation of EGFR on the cell membrane surface, thereby prolonging activation of EGFR signaling. The functional effects exerted by GPN3 are dependent on cellular levels of GTP abundance. Furthermore, our findings indicate that aberrant overexpression of GPN3 is observed in non-small cell lung cancer (NSCLC) tissues compared to adjacent normal tissues, and high expression levels of GPN3 are associated with poor prognosis for NSCLC patients. Collectively, these findings reveal that GPN3 acts as an oncogene promoting cell proliferation and migration in NSCLC through regulation of clathrin-dependent EGFR endocytosis. These results suggest that targeting GPN3 could serve as a novel prognostic biomarker and therapeutic strategy for NSCLC treatment.
小GTP酶作为调节分子在信号转导和各种细胞过程中发挥着关键作用，与包括癌症在内的人类疾病的发生发展相关。GPN3是2007年根据其结构分类的GPN环GTP酶亚家族中一个进化保守的成员，关于其细胞功能和分子机制的了解有限。在本研究中，我们证明GPN3与网格蛋白轻链A（CLTA）（一种囊泡衣被蛋白）以及网格蛋白介导的内吞作用相关调节剂AP2B1和AP2S1相互作用。GPN3的上调导致网格蛋白包被小窝内陷的抑制。此外，我们发现GPN3与表皮生长因子受体（EGFR）相互作用，并调节EGFR和CLTA的共定位，以及在表皮生长因子刺激下EGFR在早期内体中的定位。结果，这导致EGFR内吞水平降低以及EGFR在细胞膜表面的积累增加，从而延长EGFR信号的激活。GPN3发挥的功能作用取决于细胞内GTP的丰度水平。此外，我们的研究结果表明，与相邻正常组织相比，在非小细胞肺癌（NSCLC）组织中观察到GPN3异常过表达，并且GPN3的高表达水平与NSCLC患者的不良预后相关。总体而言，这些发现揭示GPN3作为一种癌基因，通过调节网格蛋白依赖性EGFR内吞作用促进NSCLC中的细胞增殖和迁移。这些结果表明，靶向GPN3可作为NSCLC治疗的一种新型预后生物标志物和治疗策略。
