title: Tubulin- and actin-associating GIMAP4 is required for IFN-γ secretion during Th cell differentiation.
abstract: Although GTPase of the immunity-associated protein (GIMAP) family are known to be most highly expressed in the cells of the immune system, their function and role remain still poorly characterized. Small GTPases in general are known to be involved in many cellular processes in a cell type-specific manner and to contribute to specific differentiation processes. Among GIMAP family, GIMAP4 is the only member reported to have true GTPase activity, and its transcription is found to be differentially regulated during early human CD4(+) T helper (Th) lymphocyte differentiation. GIMAP4 has been previously connected mainly with T- and B-cell development and survival and T-cell apoptosis. Here we show GIMAP4 to be localized into cytoskeletal elements and with the component of the trans golgi network, which suggests it to have a function in cellular transport processes. We demonstrate that depletion of GIMAP4 with RNAi results in downregulation of endoplasmic reticulum localizing chaperone VMA21. Most importantly, we discovered that GIMAP4 regulates secretion of cytokines in early differentiating human CD4(+) Th lymphocytes and in particular the secretion of interferon-γ also affecting its downstream targets.
authors.affiliation: 1] Division of Genetics and Physiology, Department of Biology, Laboratory of Animal Physiology, University of Turku, Turku, Finland [2] Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland [3] Turku Doctoral Programme of Molecular Medicine,TuDMM and Turku Doctoral Programme of Biomedical Sciences, TuBS Turku, Finland.
authors.forename: Mirkka T
authors.initials: MT
authors.lastname: Heinonen
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland.
authors.forename: Kartiek
authors.initials: K
authors.lastname: Kanduri
authors.affiliation: Department of Information and Computer Science, Aalto University Helsinki, Finland.
authors.forename: Harri J
authors.initials: HJ
authors.lastname: Lähdesmäki
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland.
authors.forename: Riitta
authors.initials: R
authors.lastname: Lahesmaa
authors.affiliation: Division of Genetics and Physiology, Department of Biology, Laboratory of Animal Physiology, University of Turku, Turku, Finland.
authors.forename: Tiina A
authors.initials: TA
authors.lastname: Henttinen
mesh_terms: D000199:Actins / Q000378:metabolism*; D002453:Cell Cycle; D002454:Cell Differentiation / Q000276:immunology*; D002470:Cell Survival; D015536:Down-Regulation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology* / Q000378:metabolism*; D014158:Transcription, Genetic; D014404:Tubulin / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D000199:Actins; C485688:GIMAP4 protein, human; D011948:Receptors, Antigen, T-Cell; D014404:Tubulin; D007371:Interferon-gamma; D019204:GTP-Binding Proteins; C540401:VMA21 protein, human; D025262:Vacuolar Proton-Translocating ATPases