SHIP-2 and PTEN Are Expressed and Active in Vascular Smooth Muscle Cell Nuclei, but Only SHIP-2 Is Associated with Nuclear Speckles
| Autor: | Jean-Pierre Salles, Bertrand Perret, Laurent Carrez, Daniel Bacqueville, Paul Déléris, Monique Breton-Douillon, Stéphanie Gayral |
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| Rok vydání: | 2003 |
| Předmět: |
Time Factors
Transcription Genetic Swine Immunoblotting Phosphatase Down-Regulation Biochemistry Muscle Smooth Vascular Phosphates Dephosphorylation Phosphatidylinositol 3-Kinases chemistry.chemical_compound Animals PTEN Tensin Inositol RNA Messenger Phosphatidylinositol Phosphorylation Molecular Biology Cell Nucleus Microscopy Confocal biology Tumor Suppressor Proteins Cell Cycle PTEN Phosphohydrolase Cell Biology Flow Cytometry Immunohistochemistry Precipitin Tests Phosphoric Monoester Hydrolases Cell biology Alternative Splicing Microscopy Fluorescence chemistry Phosphatidylinositol-3 4 5-Trisphosphate 5-Phosphatases Second messenger system biology.protein Electrophoresis Polyacrylamide Gel Cell Division Signal Transduction |
| Zdroj: | Journal of Biological Chemistry. 278:38884-38891 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m300816200 |
| Popis: | Recently, the control of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3)-dependant signaling by phosphatases has emerged, but there is a shortage of information on intranuclear PtdIns(3,4,5)P3 phosphatases. Therefore, we investigated the dephosphorylation of [32P]PtdIns(3,4,5)P3 specifically labeled on the D-3 position of the inositol ring in membrane-free nuclei isolated from pig aorta vascular smooth muscle cells (VSMCs). In vitro PtdIns(3,4,5)P3 phosphatase assays revealed the production of both [32P]PtdIns(3,4)P2 and inorganic phosphate, demonstrating the presence of PtdIns(3,4,5)P3 5- and 3-phosphatase activities inside the VSMC nucleus, respectively. Both activities presented the same potency in cellular lysates, whereas the nuclear PtdIns(3,4,5)P3 5-phosphatase activity appeared to be the most efficient. Immunoblot experiments showed for the first time the expression of the 5-phosphatase SHIP-2 (src homology 2 domain-containing inositol phosphatase) as well as the 3-phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10) in VSMC nuclei. In addition, immunoprecipitations from nuclear fractions indicated a [32P]PtdIns(3,4,5)P3 dephosphorylation by both SHIP-2 and PTEN. Moreover, confocal microscopy analyses demonstrated that SHIP-2 but not PTEN colocalized with a speckle-specific component, the SC35 splicing factor. These results suggest that SHIP-2 may be the primary enzyme for metabolizing PtdIns(3,4,5)P3 into PtdIns(3,4)P2 within the nucleus, thus producing another second messenger, whereas PTEN could down-regulate nuclear phosphoinositide 3-kinase signaling. Finally, intranuclear PtdIns(3,4,5)P3 phosphatases might be involved in the control of VSMC proliferation and the pathogenesis of vascular proliferative disorders. |
| Databáze: | OpenAIRE |
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