title: Importance of chroman ring and tyrosine phosphorylation in the subtype-specific translocation and activation of diacylglycerol kinase alpha by D-alpha-tocopherol.
abstract: Diacylglycerol kinase (DGK) has been suggested to be a pharmacological target of D-alpha-tocopherol for diabetic renal dysfunctions. However, the DGK subtypes involved in the D-alpha-tocopherol-induced improvement of diabetic renal dysfunctions and the activation mechanisms of DGK by D-alpha-tocopherol are still unknown. Therefore, using GFP-tagged DGKalpha, beta, gamma, epsilon and zeta, we analyzed their response to D-alpha-tocopherol and its derivatives. Only DGKalpha was translocated from the cytoplasm to the plasma membrane with elevation of kinase activity. In addition, troglitazone and trolox possessing 'chroman ring' similarly to D-alpha-tocopherol, induced the subtype-specific translocation of DGKalpha. Furthermore, the translocation of DGKalpha was abolished by pretreatment with tyrosine kinase inhibitors or by mutation on Tyr-334 of the kinase (YF mutant). D-alpha-tocopheryl succinate enhanced the Src-mediated tyrosine phosphorylation of wild-type DGKalpha but the same reagent did not enhance that of the YF mutant. These results demonstrate that tyrosine phosphorylation on Tyr-334 and chroman ring are important for the D-alpha-tocopherol-induced translocation of DGKalpha.
authors.affiliation: Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Nadaku, Kobe 657-8501, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Fukunaga-Takenaka
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Shirai
authors.forename: Keiko
authors.initials: K
authors.lastname: Yagi
authors.forename: Naoko
authors.initials: N
authors.lastname: Adachi
authors.forename: Norio
authors.initials: N
authors.lastname: Sakai
authors.forename: Ernesto
authors.initials: E
authors.lastname: Merino
authors.forename: Isabel
authors.initials: I
authors.lastname: Merida
authors.forename: Naoaki
authors.initials: N
authors.lastname: Saito
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002839:Chromans / Q000737:chemistry* / Q000494:pharmacology; D006224:Cricetinae; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D045162:Thiazolidinediones / Q000737:chemistry / Q000494:pharmacology; D024505:Tocopherols; D000077288:Troglitazone; D014443:Tyrosine / Q000378:metabolism*; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D002839:Chromans; D007527:Isoenzymes; D047428:Protein Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D045162:Thiazolidinediones; D014810:Vitamin E; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D019852:Diacylglycerol Kinase; D024502:alpha-Tocopherol; D000077288:Troglitazone; D024505:Tocopherols; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid