ShcA and Grb2 mediate polyoma middle T antigen-induced endothelial transformation and Gab1 tyrosine phosphorylation
ShcA and Grb2 mediate polyoma middle T antigen-induced endothelial transformation and Gab1 tyrosine phosphorylation
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DOI：
10.1093/emboj/20.22.6327
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发表时间：
2001-11-15
期刊：
影响因子：
11.4
通讯作者：
Kiefer, F
中科院分区：
文献类型：
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作者：
Ong, SH;Dilworth, S;Kiefer, F
中T抗原（PymT）是多瘤病毒的主要转化成分，可在新生小鼠中迅速诱导血管瘤。 PymT 是一种膜相关支架，可招募并激活 Src 家族酪氨酸激酶，一旦酪氨酸磷酸化，就会与具有 PTB 和 SH2 结构域的蛋白质结合，例如 ShcA、磷脂酰肌醇 3-激酶 (PI3K) 和磷脂酶 C gamma -1 (PLC gamma -1)。为了探索体内内皮转化所需的途径，我们将 PymT 突变体引入小鼠体内。与野生型类似，无法结合 PI3K 和 PLC gamma -1 的 PymT 变体直接诱导血管瘤，但无法结合 ShcA 的突变体转化受到损害。通过用 YXN 序列替换 PymT 中的该基序来抑制对 ShcA PTB 结构域结合位点的需求，YXN 序列在磷酸化时结合 Grb2 SH2 结构域。令人惊讶的是，PymT 招募 ShcA 和 Grb2 与 PI3K 激活相关。 PymT 通过形成 ShcA-Grb2-Gab1 复合物来模拟激活的受体酪氨酸激酶，从而诱导 Gab1 酪氨酸磷酸化，而 Gab1 酪氨酸磷酸化本身与 PI3K 相关。因此，PymT 激活 ShcA-Grb2 信号传导对于内皮转化至关重要，并且 PymT 可以刺激 Grb2 信号传导至 MAP 激酶和 PI3K 通路。
Middle T antigen (PymT) is the principal transforming component of polyomavirus, and rapidly induces hemangiomas in neonatal mice. PymT, a membrane-associated scaffold, recruits and activates Src family tyrosine kinases, and, once tyrosine phosphorylated, binds proteins with PTB and SH2 domains such as ShcA, phosphatidylinositol 3-kinase (PI3K) and phospholipase C gamma -1 (PLC gamma -1). To explore the pathways required for endothelial transformation in vivo, we introduced PymT mutant forms into mice. PymT variants unable to bind PI3K and PLC gamma -1 directly induced hemangiomas similarly to wild type, but a mutant unable to bind ShcA was transformation compromised. Requirement for a ShcA PTB domain-binding site was suppressed by replacing this motif in PymT with YXN sequences, which bind the Grb2 SH2 domain upon phosphorylation. Surprisingly, PymT recruitment of ShcA and Grb2 correlated with PI3K activation. PymT mimics activated receptor tyrosine kinases by forming a ShcA-Grb2-Gab1 complex, thus inducing Gab1 tyrosine phosphorylation, which itself is associated with PI3K. Therefore, PymT activation of ShcA-Grb2 signaling is critical for endothelial transformation, and PymT can stimulate Grb2 signaling to both the MAP kinase and PI3K pathways.