Li Ying-Wei, Guo Jin, Shen He, Li Jun, Yang Nuo, Frangou Costa, Wilson Kayla E, Zhang Yinglong, Mussell Ashley L, Sudol Marius, Farooq Amjad, Qu Jun, Zhang Jianmin
a Department of Cancer Genetics , Roswell Park Cancer Institute , Buffalo , NY , USA.
b Department of Pharmaceutical Sciences , New York Center of Excellence in Bioinformatics and Life Sciences, State University of New York , Buffalo , NY , USA.
Cell Cycle. 2016 Sep 16;15(18):2497-505. doi: 10.1080/15384101.2016.1207836. Epub 2016 Jul 18.
The Hippo signaling pathway regulates cellular proliferation and survival, thus exerting profound effects on normal cell fate and tumorigenesis. The pivotal effector of this pathway is YAP1, a transcriptional co-activator amplified in mouse and human cancers where it promotes epithelial-to-mesenchymal transition (EMT) and malignant transformation. The Hippo tumor suppressor pathway has been suggested to inhibit the YAP1 function through serine phosphorylation-induced cytoplasmic retention and degradation. Here we report that the tyrosine188 (Y188) site of YAP1 isoform with 2 WW domains (known as YAP1-2) plays an important role in YAP1-induced cellular transformation. IP-Mass Spectrometry analysis of YAP1 identified the phosphorylation of Y188 but not other tyrosine residues. In contrast to the aberrant 3D acinus formation observed in YAP1-WT transduced cells, overexpression of YAP1-Y188F (non-phosphorylated mimic) displayed normal 3D structures. In addition, knockdown of the endogenous YAP1 in MDA-MB231 breast cancer cells inhibited cell proliferation and migration, which were then successfully rescued by the exogenous YAP1-WT and YAP1-Y188E but not Y188F. Mechanistically, we also demonstrated that YAP1-Y188F had a higher affinity to the upstream negative regulator PTPN14 and was extensively localized in the cytoplasm. Since the Y188 is located in the conserved aromatic core of the WW domain of YAP1, our finding has a wide implication for WW domain signaling in general, where Y phosphorylation may act as a common positive regulator of the complex formation via WW domains. In summary, our results indicate that tyrosine 188 plays an important role in the YAP1-induced cellular transformation and its phosphorylation may intriguingly serve as a positive indicator of YAP1 activation.
Hippo信号通路调节细胞增殖和存活，从而对正常细胞命运和肿瘤发生产生深远影响。该通路的关键效应因子是YAP1，它是一种转录共激活因子，在小鼠和人类癌症中扩增，促进上皮-间质转化（EMT）和恶性转化。Hippo肿瘤抑制通路被认为通过丝氨酸磷酸化诱导的细胞质滞留和降解来抑制YAP1功能。在这里，我们报告具有2个WW结构域的YAP1异构体（称为YAP1-2）的酪氨酸188（Y188）位点在YAP1诱导的细胞转化中起重要作用。对YAP1的免疫沉淀-质谱分析确定了Y188的磷酸化，而不是其他酪氨酸残基。与YAP1-WT转导细胞中观察到的异常三维腺泡形成相反，YAP1-Y188F（非磷酸化模拟物）的过表达显示出正常的三维结构。此外，敲低MDA-MB231乳腺癌细胞中的内源性YAP1可抑制细胞增殖和迁移，然后外源性YAP1-WT和YAP1-Y188E而非Y188F成功挽救了这些作用。从机制上讲，我们还证明YAP1-Y188F与上游负调节因子PTPN14具有更高的亲和力，并广泛定位于细胞质中。由于Y188位于YAP1的WW结构域的保守芳香族核心中，我们的发现对一般的WW结构域信号传导具有广泛的意义,其中Y磷酸化可能作为通过WW结构域形成复合物的常见正调节因子。总之，我们的结果表明酪氨酸188在YAP1诱导的细胞转化中起重要作用，其磷酸化可能有趣地作为YAP1激活的正指标。
