Phosphorylation of the Hippo Pathway Component AMOTL2 by the mTORC2 Kinase Promotes YAP Signaling, Resulting in Enhanced Glioblastoma Growth and Invasiveness
Phosphorylation of the Hippo Pathway Component AMOTL2 by the mTORC2 Kinase Promotes YAP Signaling, Resulting in Enhanced Glioblastoma Growth and Invasiveness
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DOI：
10.1074/jbc.m115.656587
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发表时间：
2015-08-07
影响因子：
4.8
通讯作者：
Gera, Joseph
中科院分区：
文献类型：
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作者：
Artinian, Nicholas;Cloninger, Cheri;Gera, Joseph
雷帕霉素的机制靶点（mTOR）和Hippo信号通路是协调调节细胞生长和增殖的两个主要信号级联反应。这些通路的失调在胶质瘤的发生中起着关键作用。最近的报告提供了mTOR和Hippo通路之间串扰的证据;然而，这些通路之间信号关系的完整描述仍有待阐明。在小鼠神经胶质瘤模型中利用基因捕获策略，我们报告了AMOTL 2作为mTORC 2候选底物的鉴定。AMOTL 2在丝氨酸760处被mTORC 2磷酸化。模拟组成型Ser（760）磷酸化的AMOTL 2的突变阻断其结合和抑制雅普的能力，导致已知雅普基因靶标的相对表达增加。此外，AMOTL 2或不可磷酸化的AMOTL 2-S760 A突变体的过表达抑制YAP诱导的转录、病灶形成、生长和转移特性，而磷酸化模拟物AMOTL 2-S760 E突变体的过表达在体外否定了AMOTL 2在胶质母细胞瘤（GBM）细胞中的这些抑制作用。在表达这些AMOTL 2 Ser（760）突变体的GBM细胞中观察到对异种移植物生长的类似作用。雅普也被证明是Rictor介导的GBM生长和存活所必需的。最后，mTORC 2/AMOTL 2/雅普活性在原发性GBM样本中的分析支持了这种信号级联的临床相关性，我们提出共同靶向这些调节回路的药理学药物可能具有治疗潜力。
The mechanistic target of rapamycin (mTOR) and Hippo signaling pathways are two major signaling cascades that coordinately regulate cell growth and proliferation. Dysregulation of these pathways plays a critical role in gliomagenesis. Recent reports have provided evidence of cross-talk between the mTOR and Hippo pathways; however, a complete description of the signaling relationships between these pathways remains to be elucidated. Utilizing a gene-trapping strategy in a mouse glioma model, we report the identification of AMOTL2 as a candidate substrate for mTORC2. AMOTL2 is phosphorylated at serine 760 by mTORC2. Mutation of AMOTL2 mimicking constitutive Ser(760) phosphorylation blocks its ability to bind and repress YAP leading to increased relative expression of known YAP gene targets. Moreover, overexpression of AMOTL2 or a non-phosphorylatable AMOTL2-S760A mutant inhibited YAP-induced transcription, foci formation, growth, and metastatic properties, whereas overexpression of a phosphomimetic AMOTL2-S760E mutant negated these repressive effects of AMOTL2 in glioblastoma (GBM) cells in vitro. Similar effects on xenograft growth were observed in GBM cells expressing these AMOTL2 Ser(760) mutants. YAP was also shown to be required for Rictor-mediated GBM growth and survival. Finally, an analysis of mTORC2/AMOTL2/YAP activities in primary GBM samples supported the clinical relevance of this signaling cascade, and we propose that pharmacological agents cotargeting these regulatory circuits may hold therapeutic potential.