Uemura Takefumi, Suzuki Takehiro, Dohmae Naoshi, Waguri Satoshi
Department of Anatomy and Histology, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima, 960-1295, Japan.
Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Oncogenesis. 2021 Nov 19;10(11):80. doi: 10.1038/s41389-021-00367-2.
The role of Golgi/endosome-localized clathrin adapters in the maintenance of steady-state cell surface epidermal growth factor receptor (EGFR) is not well known. Here, we show that EGFR associates preferentially with both AP-1 and GGA2 in vitro. AP-1 depletion caused a reduction in the EGFR protein by promoting its lysosomal degradation. Triple immunofluorescence microscopy and proximity ligation assays demonstrated that the interaction of EGFR with AP-1 or GGA2 occurred more frequently in Rab11-positive recycling endosomes than in Rab5-positive early endosomes. Biochemical recycling assay revealed that the depletion of AP-1 or GGA2 significantly suppressed EGFR recycling to the plasma membrane regardless of the EGF stimulation. Depletion of AP-1 or GGA2 also reduced cell contents of other tyrosine kinases, MET and ErbB4, and therefore, suppressed the growth of H1975 cancer cells in culture and xenograft model. Moreover, AP-1 was expressed in endosomes at higher levels in some cancer tissues. Collectively, these results suggest that AP-1 and GGA2 function in recycling endosomes to retrieve endocytosed EGFR, thereby sustaining its cell surface expression and, consequently, cancer cell growth.
高尔基体/内体定位的网格蛋白衔接蛋白在维持稳态细胞表面表皮生长因子受体（EGFR）方面的作用尚不明确。在此，我们表明EGFR在体外优先与AP-1和GGA2结合。AP-1缺失通过促进EGFR的溶酶体降解导致其蛋白水平降低。三重免疫荧光显微镜和邻近连接分析表明，EGFR与AP-1或GGA2的相互作用在Rab11阳性的再循环内体中比在Rab5阳性的早期内体中更频繁发生。生化再循环分析显示，无论有无表皮生长因子（EGF）刺激，AP-1或GGA2的缺失均显著抑制EGFR再循环至质膜。AP-1或GGA2的缺失还降低了其他酪氨酸激酶MET和ErbB4的细胞含量，因此，抑制了培养的H1975癌细胞和异种移植模型中的细胞生长。此外，AP-1在某些癌组织的内体中表达水平更高。总体而言，这些结果表明AP-1和GGA2在再循环内体中发挥作用，以回收内吞的EGFR，从而维持其细胞表面表达，进而维持癌细胞生长。
