Ezrin is a specific and direct target of protein tyrosine phosphatase PRL-3
Ezrin is a specific and direct target of protein tyrosine phosphatase PRL-3
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DOI：
10.1016/j.bbamcr.2007.11.004
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发表时间：
2008-02-01
影响因子：
5.1
通讯作者：
Tomei, Licia
中科院分区：
文献类型：
--
作者：
Forte, Eleonora;Orsatti, Laura;Tomei, Licia
再生肝磷酸酶-3（PRL-3）是一种小的蛋白酪氨酸磷酸酶，由于其参与转移进展而被认为是有吸引力的治疗癌症靶点。然而，尽管其重要性，PRL-3作用的直接分子靶点尚不清楚。在这里，我们报告的鉴定Ezrin作为一个特定的和直接的细胞底物的PRL-3。在HCT 116结肠癌细胞系中，Ezrin被鉴定为在wtPRL-3异位过表达时磷酸化水平降低的细胞蛋白，但不包括催化失活的PRL-3突变体。虽然PRL-3在HCT 116细胞中的过表达似乎影响Ezrin在酪氨酸残基和Thr 567处的磷酸化状态，但通过RNA干扰对内源性蛋白的抑制指向Ezrin-Thr 567作为主要受PRL-3作用影响的残基。体外去磷酸化试验表明Ezrin-Thr 567是PRL-3的直接底物，也证明该酶属于双特异性磷酸酶家族。此外，在内皮细胞中观察到对pThr 567水平的相同影响，但对pTyr残基没有影响，这表明Ezrin-pThr 567去磷酸化是PRL-3在促进肿瘤进展以及建立肿瘤存活和扩增所需的新脉管系统中发挥其功能的手段。(C)2007 Elsevier B. V.保留所有权利。
Phosphatase of Regenerating Liver-3 (PRL-3) is a small protein tyrosine phosphatase considered an appealing therapeutic cancer target due to its involvement in metastatic progression. However, despite its importance, the direct molecular targets of PRL-3 action are not yet known. Here we report the identification of Ezrin as a specific and direct cellular substrate of PRL-3. In HCT116 colon cancer cell line, Ezrin was identified among the cellular proteins whose phosphorylation level decreased upon ectopic over-expression of wtPRL-3 but not of catalytically inactive PRL-3 mutants. Although PRL-3 over-expression in HCT116 cells appeared to affect Ezrin phosphorylation status at both tyrosine residues and Thr567, suppression of the endogenous protein by RNA interference pointed to Ezrin-Thr567 as the residue primarily affected by PRL-3 action. In vitro dephosphorylation assays suggested Ezrin-Thr567 as a direct substrate of PRL-3 also proving this enzyme as belonging to the dual specificity phosphatase family. Furthermore, the same effect on levels of pThr567, but not on pTyr residues, was observed in endothelial cells pointing to Ezrin-pThr567 dephosphorylation as a mean through which PRL-3 exerts its function in promoting tumor progression as well as in the establishment of the new vasculature needed for tumor survival and expansion. (C) 2007 Elsevier B.V. All rights reserved.