title: Does the dual-specificity MAPK phosphatase Pyst2-L lead a monogamous relationship with the Erk2 protein?
abstract: The dual-specificity phosphatase Pyst2-L was found to be highly expressed in leukocytes derived from AML and ALL patients as well as in certain other solid tumors and lymphoblastoid cell lines. Recently, by use of the 5'-RNA ligation-mediated rapid amplification of cDNA ends (5'-RLM-RACE) technique, we sequenced and cloned the entire open reading frame (ORF) of Pyst2-L. In the present study we determined the effect of exogenous overexpression on Erk1/2 phosphorylation. It was demonstrated that overexpression of this phosphatase in HEK293 cells reduced the basal levels of phospho-Erk1/2 as compared to the same cells transfected with the wild-type vector. This reduction was concomitant with a growth retardation of the Pyst2-L-transfected cells. Treating Pyst2-L transfected cells with known activators of the MAPK signaling cascade such as TPA or stimulating them by serum, it was demonstrated that the up regulation of phospho-Erk1/2, caused by these activators, was only partially suppressed by the over expression of the Pyst2-L phosphatase in these cells. These results together with our previous ones showing that the TPA-induced up regulation of Pyst2-L mRNA was only partially inhibited by the use of a specific Mek1/2 inhibitor, lead us to ask whether the Pyst2-L phosphatase has a monogamous relationship with the Erk2 protein. To answer this question, we employed the pull-down method and showed that in addition to phospho-Erk1/2, recombinant Pyst2-L binds the phospho-JNK protein. These findings may raise new perspectives regarding the role played by this phosphatase in malignant cells and in activation processes.
authors.affiliation: The Department of Neurobiochemistry, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, 69978 Tel Aviv, Israel.
authors.forename: Levy-Nissenbaum
authors.initials: LN
authors.lastname: Orlev
authors.forename: Barak
authors.initials: B
authors.lastname: Ehud
authors.forename: Burg-Golani
authors.initials: BG
authors.lastname: Tamar
authors.forename: Sagi-Assif
authors.initials: SA
authors.lastname: Orit
authors.forename: Kloog
authors.initials: K
authors.lastname: Yoel
authors.forename: Isaac P
authors.initials: IP
authors.lastname: Witz
mesh_terms: D054637:Dual-Specificity Phosphatases; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000276:immunology / Q000378:metabolism; D007951:Leukemia, Myeloid / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000276:immunology / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D010749:Phosphoprotein Phosphatases; C107523:DUSP7 protein, human; D054637:Dual-Specificity Phosphatases; D017027:Protein Tyrosine Phosphatases