Direct identification of PTEN phosphorylation sites

FEBS Letters

Miller, Susan J.¹  Neel, Benjamin G.¹  Lane, William S.²  Seldin, David C.³  Lou, David Y.³ 

[1] Cancer Biology Program, Division of Hematology–Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave., Boston, MA 02215, USA;Harvard Microchemistry and Proteomics Analysis Facility, 16 Divinity Avenue, Cambridge, MA 02138, USA;Departments of Medicine and Microbiology, Boston University Medical Center, Boston, MA 02118, USA

关键词: PTEN;    Phosphatase;    Protein phosphorylation;    Protein kinase CK2;    CK2;    protein kinase CK2 or casein kinase II;    DMEM;    Dulbecco's modified Eagle's medium;    MS;    mass spectrometry;    PIP3;    phosphatidylinositol 3;    4;    5-triphosphate;    PI3K;    phosphatidylinositol 3-kinase;    PAGE;    polyacrylamide gel electrophoresis;    SDS;    sodium dodecyl sulfate;   

DOI  :  10.1016/S0014-5793(02)03274-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The PTEN tumor suppressor gene encodes a phosphatidylinositol 3′-phosphatase that is inactivated in a high percentage of human tumors, particularly glioblastoma, melanoma, and prostate and endometrial carcinoma. Previous studies showed that PTEN is a seryl phosphoprotein and a substrate of protein kinase CK2 (CK2). However, the sites in PTEN that are phosphorylated in vivo have not been identified directly, nor has the effect of phosphorylation on PTEN catalytic activity been reported. We used mass spectrometric methods to identify Ser³⁷⁰ and Ser³⁸⁵ as in vivo phosphorylation sites of PTEN. These sites also are phosphorylated by CK2 in vitro, and phosphorylation inhibits PTEN activity towards its substrate, PIP3. We also identify a novel in vivo phosphorylation site, Thr³⁶⁶. Following transient over-expression, a fraction of CK2 and PTEN co-immunoprecipitate. Moreover, pharmacological inhibition of CK2 activity leads to decreased Akt activation in PTEN+/+ but not PTEN−/− fibroblasts. Our results contrast with previous assignments of PTEN phosphorylation sites based solely on mutagenesis approaches, suggest that CK2 is a physiologically relevant PTEN kinase, and raise the possibility that CK2-mediated inhibition of PTEN plays a role in oncogenesis.

【 授权许可】

Unknown