title: Low cytoplasmic pH reduces ER-Golgi trafficking and induces disassembly of the Golgi apparatus.
abstract: The Golgi apparatus was dramatically disassembled when cells were incubated in a low pH medium. The cis-Golgi disassembled quickly, extended tubules and spread to the periphery of cells within 30 min. In contrast, medial- and trans-Golgi were fragmented in significantly larger structures of smaller numbers at a slower rate and remained largely in structures distinct from the cis-Golgi. Electron microscopy revealed the complete disassembly of the Golgi stack in low pH treated cells. The effect of low pH was reversible; the Golgi apparatus reassembled to form a normal ribbon-like structure within 1-2h after the addition of a control medium. The anterograde ER to Golgi transport and retrograde Golgi to ER transport were both reduced under low pH. Phospholipase A2 inhibitors (ONO, BEL) effectively suppressed the Golgi disassembly, suggesting that the phospholipase A2 was involved in the Golgi disassembly. Over-expression of Rab1, 2, 30, 33 and 41 also suppressed the Golgi disassembly under low pH, suggesting that they have protective role against Golgi disassembly. Low pH treatment reduced cytoplasmic pH, but not the luminal pH of the Golgi apparatus, strongly suggesting that reduction of the cytoplasmic pH triggered the Golgi disassembly. Because a lower cytoplasmic pH is induced in physiological or pathological conditions, disassembly of the Golgi apparatus and reduction of vesicular transport through the Golgi apparatus may play important roles in cell physiology and pathology. Furthermore, our findings indicated that low pH treatment can serve as an important tool to analyze the molecular mechanisms that support the structure and function of the Golgi apparatus.
authors.affiliation: Laboratory for Cell and Developmental Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan.
authors.forename: Jeerawat
authors.initials: J
authors.lastname: Soonthornsit
authors.affiliation: Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tamura
authors.affiliation: Laboratory for Cell and Developmental Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Ishida
authors.affiliation: Laboratory for Cell and Developmental Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nakakoji
authors.affiliation: Laboratory for Cell and Developmental Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan.
authors.forename: Shiho
authors.initials: S
authors.lastname: Osako
authors.affiliation: Department of Animal Bioscience, Nagahama Institute of Bio-Science and Technology, 266 Tamura, Nagahama, Shiga, 526-0829, Japan.
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: Laboratory for Cell and Developmental Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita, Kyoto 603-8555, Japan; Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan. Electronic address: osaru3@cc.kyoto-su.ac.jp.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D001692:Biological Transport / Q000502:physiology*; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron; D054467:Phospholipases A2 / Q000378:metabolism
chemical_list: D054467:Phospholipases A2
keywords: Acidosis; Brefeldin A; Cis-Golgi; Live-cell imaging; Tubular extension