title: Evidence for regulation of the PTEN tumor suppressor by a membrane-localized multi-PDZ domain containing scaffold protein MAGI-2.
abstract: PTEN is a tumor suppressor gene mutated in human cancers. Although many mutations target the phosphatase domain, others create a truncated protein lacking the C-terminal PDZ-binding motif or a protein that extends beyond the PDZ-binding motif. Using the yeast two-hybrid system, we isolated a membrane-associated guanylate kinase family protein with multiple PDZ domains [AIP-1 (atrophin interacting protein 1), renamed MAGI-2 (membrane associated guanylate kinase inverted-2)]. MAGI-2 contains eight potential protein-protein interaction domains and is localized to tight junctions in the membrane of epithelial cells. PTEN binds to MAGI-2 through an interaction between the PDZ-binding motif of PTEN and the second PDZ domain of MAGI-2. MAGI-2 enhances the ability of PTEN to suppress Akt activation. Furthermore, certain PTEN mutants have reduced stability, which is restored by adding the minimal PDZ-binding motif back to the truncated protein. We propose that MAGI-2 improves the efficiency of PTEN signaling through assembly of a multiprotein complex at the cell membrane.
authors.affiliation: Department of Medicine, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
authors.forename: X
authors.initials: X
authors.lastname: Wu
authors.forename: K
authors.initials: K
authors.lastname: Hepner
authors.forename: S
authors.initials: S
authors.lastname: Castelino-Prabhu
authors.forename: D
authors.initials: D
authors.lastname: Do
authors.forename: M B
authors.initials: MB
authors.lastname: Kaye
authors.forename: X J
authors.initials: XJ
authors.lastname: Yuan
authors.forename: J
authors.initials: J
authors.lastname: Wood
authors.forename: C
authors.initials: C
authors.lastname: Ross
authors.forename: C L
authors.initials: CL
authors.lastname: Sawyers
authors.forename: Y E
authors.initials: YE
authors.lastname: Whang
mesh_terms: D005786:Gene Expression Regulation / Q000235:genetics*; D016147:Genes, Tumor Suppressor; D051528:Guanylate Kinases; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics* / Q000378:metabolism; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D025521:Tumor Suppressor Proteins
chemical_list: D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human