Antibody-induced dimerization of FGFR1 promotes receptor endocytosis independently of its kinase activity
Antibody-induced dimerization of FGFR1 promotes receptor endocytosis independently of its kinase activity
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DOI：
10.1038/s41598-017-07479-z
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发表时间：
2017-08-02
影响因子：
4.6
通讯作者：
Otlewski, Jacek
中科院分区：
文献类型：
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作者：
Opalinski, Lukasz;Sokolowska-Wedzina, Aleksandra;Otlewski, Jacek
成纤维细胞生长因子（FGF）及其质膜定位受体（FGFR）在发育过程和代谢的调节中起着关键作用。异常FGFR信号传导与严重代谢疾病和人类癌症的进展相关。FGF与FGFR的结合诱导受体二聚化和FGFR激酶结构域的转磷酸化，其触发细胞内信号传导途径的活化。活化后，FGFR经历内化和随后的溶酶体降解，其终止信号的传递。尽管调控FGFR内吞作用的因子不断被发现，但对启动FGFR内化的分子机制知之甚少。在这里，我们分析了靶向FGFR 1的各种形式的抗体片段的内化。我们表明，单价scFv形式的FGFR 1特异性抗体片段与FGFR 1结合，但不会内化到过度产生FGFR 1的细胞中。相反，二价scFv-Fc形式的相同scFv蛋白通过FGFR 1介导的网格蛋白和发动蛋白依赖性内吞作用有效内化。有趣的是，对于scFv-Fc-FGFR 1复合物的内吞作用，受体酪氨酸激酶活性是不稳定的，这表明仅需要受体的二聚化来触发FGFR 1复合物的内吞作用。
Fibroblast growth factors (FGFs) and their plasma membrane-localized receptors (FGFRs) play a key role in the regulation of developmental processes and metabolism. Aberrant FGFR signaling is associated with the progression of serious metabolic diseases and human cancer. Binding of FGFs to FGFRs induces receptor dimerization and transphosphorylation of FGFR kinase domains that triggers activation of intracellular signaling pathways. Following activation, FGFRs undergo internalization and subsequent lysosomal degradation, which terminates transmission of signals. Although factors that regulate FGFR endocytosis are continuously discovered, little is known about the molecular mechanism that initiates the internalization of FGFRs. Here, we analyzed the internalization of antibody fragments in various formats that target FGFR1. We show that FGFR1-specific antibody fragments in the monovalent scFv format bind to FGFR1, but are not internalized into cells that overproduce FGFR1. In contrast, the same scFv proteins in the bivalent scFv-Fc format are efficiently internalized via FGFR1-mediated, clathrin and dynamin dependent endocytosis. Interestingly, the receptor tyrosine kinase activity is dispensable for endocytosis of scFv-Fc-FGFR1 complexes, suggesting that only dimerization of receptor is required to trigger endocytosis of FGFR1 complexes.