Modulation of protein tyrosine phosphatase 1B by erythropoietin in UT-7 cell line
Background/ Aims: Since the reversible phosphorylation of tyrosyl residues is a critical event in cellular signaling pathways activated by erythropoietin (Epo), attention has been focused on protein tyrosine phosphatases (PTPs) and their coordinated action with protein tyrosine kinases. The prototyp...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2007 |
| País: | Argentina |
| Institución: | Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales |
| Repositorio: | Biblioteca Digital (UBA-FCEN) |
| Idioma: | inglés |
| OAI Identifier: | paperaa:paper_10158987_v20_n5_p319_Callero |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_10158987_v20_n5_p319_Callero |
| Access Level: | acceso abierto |
| Palabra clave: | Erythropoietin Protein Tyrosine Phosphatase 1B UT-7 cell line 4 nitrophenylphosphatase erythropoietin Janus kinase 2 phosphatidylinositol 3 kinase protein tyrosine phosphatase 1B article controlled study enzyme activity enzyme phosphorylation feedback system human human cell hydrolysis priority journal protein expression protein function real time polymerase chain reaction signal transduction Western blotting 1-Phosphatidylinositol 3-Kinase Cell Line Cell Survival Down-Regulation Gene Expression Regulation, Enzymologic Janus Kinase 2 Phosphorylation Protein-Tyrosine-Phosphatase Tyrphostins |
| Sumario: | Background/ Aims: Since the reversible phosphorylation of tyrosyl residues is a critical event in cellular signaling pathways activated by erythropoietin (Epo), attention has been focused on protein tyrosine phosphatases (PTPs) and their coordinated action with protein tyrosine kinases. The prototypic member of the PTP family is PTP1B, a widely expressed non-receptor PTP located both in cytosol and intracellular membranes via its hydrophobic C-terminal targeting sequence. PTP1B has been implicated in the regulation of signaling pathways involving tyrosine phosphorylation induced by growth factors, cytokines, and hormones, such as the downregulation of erythropoietin and insulin receptors. However, little is known about which factor modulates the activity of this enzyme. Methods: The effect of Epo on PTP1B expression was studied in the UT-7 Epo-dependent cell line. PTP1B expression was analyzed under different conditions by Real-Time PCR and Western blot, while PTP1B phosphatase activity was determined by a p-nitrophenylphosphate hydrolysis assay. Results: Epo rapidly induced an increased expression of PTP1B which was associated with higher PTP1B tyrosine phosphorylation and phosphatase activity. The action of Epo on PTP1B induction involved Janus Kinase 2 (JAK2) and Phosphatidylinositol-3 kinase (PI3K). Conclusion: The results allow us to suggest for the first time that, besides modulating Epo/Epo receptor signaling, PTP1B undergoes feedback regulation by Epo. Copyright © 2007 S. Karger AG. |
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