Mills Jack V, Osher Eliot, Rieunier Guillaume, Mills Ian G, Macaulay Valentine M
Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ UK.
Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.
Discov Oncol. 2021;12(1):13. doi: 10.1007/s12672-021-00407-8. Epub 2021 Apr 29.
Mature type 1 insulin-like growth factor receptors (IGF-1Rs) are heterotetrameric structures comprising two extracellular α-subunits disulphide-bonded to two transmembrane β-subunits with tyrosine kinase activity. IGF-1R is a well-known cell surface mediator of malignant growth, with an incompletely understood role upon nuclear import as a transcriptional regulator. Previous characterisation of nuclear IGF-1R focused on IGF-1Rβ. Here, we aimed to clarify the source of nuclear IGF-1R and investigate whether α-subunits contribute to nuclear IGF-1R function. Using prostate cancer cell lines DU145 and 22Rv1 we detected nuclear α- and β-subunits, with increase in nuclear signal upon IGF-treatment and reduction in response to IGF-1R inhibitor BMS-754807. Following biotinylation of cell surface proteins, biotinylated α- and β-subunits were detected in nuclear extracts of both cell lines. Furthermore, α- and β-subunits reciprocally co-precipitated from nuclear extract. Finally, we detected recruitment of both subunits to regulatory regions of chromatin, including the promoter of the oncogene , that we previously identified in ChIP-seq as sites of IGF-1Rβ enrichment. These data confirm the cell surface origin of nuclear IGF-1R, suggest the presence of nuclear αβ complexes and reveal that both IGF-1Rα- and β-subunits contribute to pro-tumorigenic functions of nuclear IGF-1R.
The online version contains supplementary material available at 10.1007/s12672-021-00407-8.
成熟的1型胰岛素样生长因子受体（IGF-1R）是异源四聚体结构，由两个通过二硫键与两个具有酪氨酸激酶活性的跨膜β亚基相连的细胞外α亚基组成。IGF-1R是一种众所周知的恶性生长细胞表面介质，其作为转录调节因子在核输入中的作用尚不完全清楚。先前对核IGF-1R的表征集中在IGF-1Rβ上。在这里，我们旨在阐明核IGF-1R的来源，并研究α亚基是否有助于核IGF-1R的功能。使用前列腺癌细胞系DU145和22Rv1，我们检测到核α和β亚基，IGF处理后核信号增加，对IGF-1R抑制剂BMS-754807的反应降低。在对细胞表面蛋白进行生物素化后，在两种细胞系的核提取物中检测到生物素化的α和β亚基。此外，α和β亚基从核提取物中相互共沉淀。最后，我们检测到两个亚基都被募集到染色质的调控区域，包括癌基因的启动子，我们之前在ChIP-seq中确定其为IGF-1Rβ富集位点。这些数据证实了核IGF-1R的细胞表面起源，表明存在核αβ复合物，并揭示IGF-1Rα和β亚基都有助于核IGF-1R的促肿瘤功能。
在线版本包含可在10.1007/s12672-021-00407-8获取的补充材料。
