Ahn, Younghee Hwang, Chae Young Lee, Seung-Rock Kwon, Ki-Sun Lee, Cheolju 2024-01-20T23:03:58Z 2024-01-20T23:03:58Z 2021-09-03 2008-06-01 0264-6021 https://pubs.kist.re.kr/handle/201004/133404 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. English PORTLAND PRESS LTD EXPRESSION ANALYSIS APOPTOSIS PROTEINS MASS-SPECTROMETRY CANCER CELLS KINASE MST2 PATHWAY MDM2 PHOSPHATASE GENE P53 The tumour suppressor PTEN mediates a negative regulation of the E3 ubiquitin-protein ligase Nedd4 Article 10.1042/BJ20071403 1 BIOCHEMICAL JOURNAL, v.412, pp.331 - 338 BIOCHEMICAL JOURNAL 412 331 338 scie scopus 000256491900015 2-s2.0-44449158749 Biochemistry & Molecular Biology Biochemistry & Molecular Biology Article EXPRESSION ANALYSIS APOPTOSIS PROTEINS MASS-SPECTROMETRY CANCER CELLS KINASE MST2 PATHWAY MDM2 PHOSPHATASE GENE P53 apoptosis feedback regulator MS neural-precursor-cell-expressed developmentally down-regulated gene 4 (Nedd4) phosphatase and tensin homologue deleted on chromosome 10 (PTEN) transcriptional regulation