title: NOGO-A/RTN4A and NOGO-B/RTN4B are simultaneously expressed in epithelial, fibroblast and neuronal cells and maintain ER morphology.
abstract: Reticulons (RTNs) are a large family of membrane associated proteins with various functions. NOGO-A/RTN4A has a well-known function in limiting neurite outgrowth and restricting the plasticity of the mammalian central nervous system. On the other hand, Reticulon 4 proteins were shown to be involved in forming and maintaining endoplasmic reticulum (ER) tubules. Using comparative transcriptome analysis and qPCR, we show here that NOGO-B/RTN4B and NOGO-A/RTN4A are simultaneously expressed in cultured epithelial, fibroblast and neuronal cells. Electron tomography combined with immunolabelling reveal that both isoforms localize preferably to curved membranes on ER tubules and sheet edges. Morphological analysis of cells with manipulated levels of NOGO-B/RTN4B revealed that it is required for maintenance of normal ER shape; over-expression changes the sheet/tubule balance strongly towards tubules and causes the deformation of the cell shape while depletion of the protein induces formation of large peripheral ER sheets.
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Olli
authors: O
authors: Rämö
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Darshan
authors: D
authors: Kumar
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Erika
authors: E
authors: Gucciardo
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Merja
authors: M
authors: Joensuu
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Maiju
authors: M
authors: Saarekas
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.|Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Helena
authors: H
authors: Vihinen
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.|Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Ilya
authors: I
authors: Belevich
authors: DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Olli-Pekka
authors: OP
authors: Smolander
authors: DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Kui
authors: K
authors: Qian
authors: DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Petri
authors: P
authors: Auvinen
authors: Cell and Molecular Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.|Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Eija
authors: E
authors: Jokitalo
mesh_terms: D000818:Animals; D002460:Cell Line; D048430:Cell Shape; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D020869:Gene Expression Profiling; D006801:Humans; D051379:Mice; D016253:Microscopy, Immunoelectron; D041681:NIH 3T3 Cells; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D000070798:Nogo Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000070798:Nogo Proteins; D020033:Protein Isoforms; C000603199:RTN4 protein, human; C000603201:Rtn4 protein, mouse