Akagi T, Shishido T, Murata K, Hanafusa H
Laboratory of Molecular Oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2000 Jun 20;97(13):7290-5. doi: 10.1073/pnas.140210297.
v-Crk induces cellular tyrosine phosphorylation and transformation of chicken embryo fibroblasts (CEF). We studied the molecular mechanism of the v-Crk-induced transformation. Experiments with Src homology (SH)2 and SH3 domain mutants revealed that the induction of tyrosine phosphorylation of cellular proteins requires only the SH2 domain, but both the SH2 and SH3 domains are required for complete transformation. Analysis of three well defined signaling pathways, the mitogen-activated protein kinase (MAPK) pathway, the Jun N-terminal kinase (JNK) pathway, and the phosphoinositide 3-kinase (PI3K)/AKT pathway, demonstrated that only the PI3K/AKT pathway is constitutively activated in v-Crk-transformed CEF. Both the SH2 and SH3 domains are required for this activation of the PI3K/AKT pathway in CEF. We also found that the colony formation of CEF is strongly induced by a constitutively active PI3K mutant, and that a PI3K inhibitor, LY294002, suppresses the v-Crk-induced transformation. These results strongly suggest that constitutive activation of the PI3K/AKT pathway plays an essential role in v-Crk-induced transformation of CEF.
v-Crk诱导鸡胚成纤维细胞（CEF）发生细胞酪氨酸磷酸化和转化。我们研究了v-Crk诱导转化的分子机制。对Src同源（SH）2和SH3结构域突变体的实验表明，细胞蛋白酪氨酸磷酸化的诱导仅需要SH2结构域，但完全转化则需要SH2和SH3结构域。对三条明确的信号通路，即丝裂原活化蛋白激酶（MAPK）通路、Jun N端激酶（JNK）通路和磷酸肌醇3激酶（PI3K）/AKT通路的分析表明，在v-Crk转化的CEF中只有PI3K/AKT通路被组成性激活。CEF中PI3K/AKT通路的这种激活需要SH2和SH3结构域。我们还发现，组成性激活的PI3K突变体强烈诱导CEF的集落形成，并且PI3K抑制剂LY294002抑制v-Crk诱导的转化。这些结果强烈表明，PI3K/AKT通路的组成性激活在v-Crk诱导的CEF转化中起重要作用。
