Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine (SJTU-SM), Shanghai 200025, China.
Department of Ophthalmology, Ninth People's Hospital, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Jiao Tong University School of Medicine (SJTU-SM), Shanghai 200025, China.
Neoplasia. 2020 Mar;22(3):129-141. doi: 10.1016/j.neo.2019.12.004. Epub 2020 Jan 22.
Numerous studies have reported that c-Src is highly expressed with high tyrosine kinase activity in a variety of tumors. However, it remains unclear whether c-Src contributes to the miRNA pathway. Here, we report that c-Src can interact with and phosphorylate AGO2, a core component of RISC complex, at tyr 393, tyr 529 and tyr749. Mechanistically, it is confirmed that c-Src phosphorylation of AGO2 at tyr393 reduces its binding to DICER, thereby suppressing the maturation of long-loop pre-miR-192. However, the other two phosphorylation sites don't work on this function. Significantly, Ectopic expression of wild-type AGO2, but not the three tyrosine site mutants, has an obvious tumor-promoting effect in vitro and in vivo, which function could be blocked thoroughly by treatment with c-Src kinase inhibitor, Saracatinib. Our findings identify AGO2 as c-Src target and c-Src phosphorylation of AGO2 may therefore play a potential role during tumor progress.
大量研究报道，在多种肿瘤中 c-Src 呈现高度表达并具有高酪氨酸激酶活性。然而，c-Src 是否有助于 miRNA 通路仍不清楚。在这里，我们报告 c-Src 可以与 RISC 复合物的核心组成部分 AGO2 相互作用，并在 tyr 393、tyr 529 和 tyr749 处磷酸化 AGO2。从机制上讲，已经证实 c-Src 在 tyr393 处对 AGO2 的磷酸化会降低其与 DICER 的结合，从而抑制长环 pre-miR-192 的成熟。然而，另外两个磷酸化位点在该功能上不起作用。重要的是，野生型 AGO2 的异位表达，而不是三个酪氨酸位点突变体，在体外和体内具有明显的促肿瘤作用，而用 c-Src 激酶抑制剂 Saracatinib 处理可完全阻断其功能。我们的研究结果确定 AGO2 为 c-Src 的靶标，AGO2 的 c-Src 磷酸化在肿瘤进展过程中可能发挥潜在作用。
