Ezrin is a specific and direct target of protein tyrosine phosphatase PRL-3.
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.
Forte
Eleonora
E
IRBM P. Angeletti, via Pontina, Pomezia, Rome, Italy.
Orsatti
Laura
L
Talamo
Fabio
F
Barbato
Gaetano
G
De Francesco
Raffaele
R
Tomei
Licia
L
D002384:Catalysis / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D045325:HCT116 Cells; D006801:Humans; D050505:Mutant Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D034622:RNA Interference; D013379:Substrate Specificity / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000099149:Ezrin
D003598:Cytoskeletal Proteins; D050505:Mutant Proteins; D009363:Neoplasm Proteins; D010769:Phosphothreonine; D019000:Phosphotyrosine; D017027:Protein Tyrosine Phosphatases; D013755:Tetradecanoylphorbol Acetate; D000099149:Ezrin; C484730:PTP4A3 protein, human