title: Delta-catenin/NPRAP (neural plakophilin-related armadillo repeat protein) interacts with and activates sphingosine kinase 1.
abstract: Sphingosine kinase (SPHK) is a key enzyme catalysing the formation of sphingosine 1-phosphate (SPP), a lipid messenger that is implicated in the regulation of a wide variety of important cellular events acting through intracellular, as well as extracellular, mechanisms. However, the molecular mechanism of intracellular actions of SPP remains unclear. Here, we have identified delta-catenin/NPRAP (neural plakophilin-related armadillo repeat protein) as a potential binding partner for SPHK1 by yeast two-hybrid screening. From co-immunoprecipitation analyses, the C-terminal portion of delta-catenin/NPRAP containing the seventh to tenth armadillo repeats was found to be required for interaction with SPHK1. Endogenous delta-catenin/NPRAP was co-localized with endogenous SPHK1 and transfected delta-catenin/NPRAP was co-localized with transfected SPHK1 in dissociated rat hippocampal neurons. MDCK (Madin-Darby canine kidney) cells stably expressing delta-catenin/NPRAP contained elevated levels of intracellular SPP. In a purified system delta-catenin/NPRAP stimulated SPHK1 in a dose-dependent manner. Furthermore, delta-catenin/NPRAP-induced increased cell motility in MDCK cells was completely inhibited by dimethylsphingosine, a specific inhibitor of SPHK1. These results strongly suggest that at least some of delta-catenin/NPRAP functions, including increased cell motility, are mediated by an SPHK-SPP signalling pathway.
authors.affiliation: Division of Biochemistry, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
authors.forename: Toshitada
authors.initials: T
authors.lastname: Fujita
authors.forename: Taro
authors.initials: T
authors.lastname: Okada
authors.forename: Shun
authors.initials: S
authors.lastname: Hayashi
authors.forename: Saleem
authors.initials: S
authors.lastname: Jahangeer
authors.forename: Noriko
authors.initials: N
authors.lastname: Miwa
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D051186:Armadillo Domain Proteins; D019556:COS Cells / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D051177:Catenins; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000737:chemistry / Q000201:enzymology; D006801:Humans; D007668:Kidney / Q000737:chemistry / Q000196:embryology / Q000201:enzymology / Q000378:metabolism; D008246:Lysophospholipids / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011247:Pregnancy; D025941:Protein Interaction Mapping / Q000379:methods; D017434:Protein Structure, Tertiary; D051381:Rats; D017208:Rats, Wistar; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D020080:Tandem Repeat Sequences / Q000235:genetics; D020798:Two-Hybrid System Techniques; D000095002:Delta Catenin
chemical_list: D051186:Armadillo Domain Proteins; D051177:Catenins; D008246:Lysophospholipids; D009419:Nerve Tissue Proteins; D010455:Peptides; C060506:sphingosine 1-phosphate; D013110:Sphingosine; D000095002:Delta Catenin