Santoro M M, Penengo L, Orecchia S, Cilli M, Gaudino G
Dibit-HSR, via Olgettina 58, I-20138, Milano, Italy.
Oncogene. 2000 Oct 26;19(45):5208-11. doi: 10.1038/sj.onc.1203819.
Oncogenic activation of the Ron tyrosine kinase (Macrophage Stimulating Protein receptor) relies on substitutions of two highly conserved residues in the catalytic domain (D1232V and M1254T), which result in ligand-independent activation of the receptor, in vivo tumorigenesis and metastasis. We show here that the Y/F conversion of the Y1317 residue in the kinase domain impairs tumorigenic and metastatic properties of Ron activated by the MEN2B-like mutation (RonM1254T), but not by other two oncogenic substitutions. Furthermore, RonM1254T lacking the multifunctional docking site retains transforming and metastatic activity. These data reveal that the transforming activity of RonM1254T mutant is dependent on Y1317 phosphorylation, suggesting a shift in intramolecular substrate specificity. Consistently, a shift of RonM1254T kinase substrate specificity was observed by in vitro peptide phosphorylation assays and in vivo receptor auto-phosphorylation. The Y1317 phosphorylation elicits by itself activation of PI-3K/Akt and MAPK signalling pathways. Our data indicate that the accomplishment of the full oncogenic phenotype of RonM1254T requires the phosphorylation both of the canonical C-terminal docking site and of the unique Y1317 residue in the tyrosine kinase domain.
Ron酪氨酸激酶（巨噬细胞刺激蛋白受体）的致癌激活依赖于催化结构域中两个高度保守残基的替换（D1232V和M1254T），这导致受体的配体非依赖性激活、体内肿瘤发生和转移。我们在此表明，激酶结构域中Y1317残基的Y/F转换会损害由MEN2B样突变（RonM1254T）激活的Ron的致瘤和转移特性，但不会损害其他两种致癌替换所激活的Ron的致瘤和转移特性。此外，缺乏多功能对接位点的RonM1254T保留了转化和转移活性。这些数据表明，RonM1254T突变体的转化活性依赖于Y1317磷酸化，提示分子内底物特异性发生了改变。一致地，通过体外肽磷酸化测定和体内受体自身磷酸化观察到RonM1254T激酶底物特异性的改变。Y1317磷酸化自身引发PI-3K/Akt和MAPK信号通路的激活。我们的数据表明，RonM1254T完全致癌表型的实现需要酪氨酸激酶结构域中经典C末端对接位点和独特的Y1317残基的磷酸化。
