The tumour suppressor PTEN mediates a negative regulation of the E3 ubiquitin-protein ligase Nedd4.
The tumour suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10; a phosphatidylinositol 3-phosphatase) is a multifunctional protein deregulated in many types of cancer. It is suggested that a number of proteins that relate with PTEN functionally or physically have not yet been found. In order to search for ... PTEN-interacting proteins that might be crucial in the regulation of PTEN, we exploited a proteomics-based approach. PTEN-expressing NIH 3T3 cell lysates were used in affinity chromatography and then analysed by LC-ESI-MS/MS (liquid chromatography-electrospray ionization-tandem MS). A total of 93 proteins were identified. Among the proteins identified, we concentrated on the E3 ubiquitin-protein ligase Nedd4 (neural-precursor-cell-expressed, developmentally down-regulated gene 4), and performed subsequent validation experiments using HeLa cells. Nedd4 inhibited PTEN-induced apoptotic cell death and, conversely, the Nedd4 level was down-regulated by PTEN. The down-regulation effect was diminished by a mutation (C124S) in the catalytic site of PTEN. Nedd4 expression was also decreased by a PI3K (phosphoinositide 3-kinase) inhibitor, LY294002, suggesting that the regulation is dependent on the phosphatase-kinase activity of the PTEN-PI3K/Akt pathway. Semi-quantitative real-time PCR analysis revealed that Nedd4 was transcriptionally regulated by PTEN. Thus our results have important implications regarding the roles of PTEN upon the E3 ubquitin ligase Nedd4 as a negative feedback regulator as well as a substrate.
Mesh Terms:
Animals, Apoptosis, Caspases, Endosomal Sorting Complexes Required for Transport, Gene Expression Regulation, HeLa Cells, Humans, Mice, NIH 3T3 Cells, PTEN Phosphohydrolase, Phosphatidylinositol 3-Kinases, Proteome, Proto-Oncogene Proteins c-akt, RNA, Small Interfering, Signal Transduction, Transcription, Genetic, Tumor Suppressor Proteins, Ubiquitin-Protein Ligases, X-Linked Inhibitor of Apoptosis Protein
Animals, Apoptosis, Caspases, Endosomal Sorting Complexes Required for Transport, Gene Expression Regulation, HeLa Cells, Humans, Mice, NIH 3T3 Cells, PTEN Phosphohydrolase, Phosphatidylinositol 3-Kinases, Proteome, Proto-Oncogene Proteins c-akt, RNA, Small Interfering, Signal Transduction, Transcription, Genetic, Tumor Suppressor Proteins, Ubiquitin-Protein Ligases, X-Linked Inhibitor of Apoptosis Protein
Biochem. J.
Date: Jun. 01, 2008
PubMed ID: 18307411
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