Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
Biofactors. 2021 May;47(3):351-362. doi: 10.1002/biof.1709. Epub 2021 Jan 27.
Epidermal growth factor (EGF) has vital biological impacts on the osteoblasts. However, the knowledge on the cellular properties of EGF/EGFR (epidermal growth factor receptor) on osteoblasts is scanty. As such, we explored the EGF/EGFR's cell behavior in the osteoblast (MC3T3-E1 cell) using the indirect immunofluorescence assay, Western-blot, and fluorescence resonance energy transfer. Our findings revealed that EGF could internalize into the cytoplasm under EGFR mediation. Besides, the co-localization analysis demonstrated that caveolin played a critical role in EGFR's endocytosis. We also analyzed the cytoplasmic trafficking pathway of EGF/EGFR in MC3T3-E1 cell. The colocalization analysis showed that EGFR entered into Rab5, Rab4, and Rab9-positive endosomes. More importantly, we found that EGFR could move into the MC3T3-E1 cells' nuclei. Based on this, we investigated the EGFR's nuclear-localized functions, and the results suggested that nuclear-localized EGFR has important biological functions. This work lays a foundation for further study on EGF/EGFR's biological functions on the osteoblasts.
表皮生长因子（EGF）对成骨细胞有重要的生物学影响。然而，关于 EGF/表皮生长因子受体（EGFR）对成骨细胞的细胞特性的知识还很缺乏。因此，我们使用间接免疫荧光法、Western blot 和荧光共振能量转移技术研究了 EGF/EGFR 在成骨细胞（MC3T3-E1 细胞）中的细胞行为。我们的研究结果表明，EGF 可以在 EGFR 介导下内化到细胞质中。此外，共定位分析表明 caveolin 在 EGFR 的内化中起关键作用。我们还分析了 EGF/EGFR 在 MC3T3-E1 细胞中的胞质运输途径。共定位分析表明，EGFR 进入 Rab5、Rab4 和 Rab9 阳性内体。更重要的是，我们发现 EGFR 可以进入 MC3T3-E1 细胞的细胞核。基于此，我们研究了 EGFR 的核定位功能，结果表明核定位的 EGFR 具有重要的生物学功能。这项工作为进一步研究 EGF/EGFR 对成骨细胞的生物学功能奠定了基础。
