title: Functional link between Rab GTPase-mediated membrane trafficking and PI4,5P2 signaling.
abstract: Fission yeast its3(+) encodes an essential phosphatidylinositol-4-phosphate 5-kinase (PI4P5K) that regulates cell integrity and cytokinesis. We performed a genetic screen to identify genes that function in PI4P5K-mediated signaling, and identified gyp10(+) encoding a Rab GTPase-activating protein (GAP), a negative regulator for Rab GTPase signaling. Its3 overproduction caused growth defects and abnormal cytoplasmic accumulation of the Its3 protein, which can be stained by calcofluor. Notably, Its3 overproducing cells displayed abnormal membranous structures, multilamella Golgi and fragmented vacuoles showed by Electron microscopy. Furthermore, the excess cytoplasmic Its3 structure partly colocalized with the fluorescence of FM4-64. Gyp10 rescued both growth defects and abnormal Its3 localization when it was over-expressed. Gyp10 functionally interacted with the Rab GTPases Ypt3 and Ryh1, both of which regulate Golgi membrane trafficking. Consistently, mutation or deletion of Ypt3 and Ryh1 suppressed phenotypes associated with Its3 overproduction. Importantly, the plasma membrane localization of Its3 was also affected by the impairment of the Ypt3/Ryh1 Rab membrane trafficking, thus suggesting that membrane trafficking events regulated by two Rab GTPases functionally interacts with PI4,5P2 signaling. These results suggest a mechanism whereby PI4P5K signaling/localization is affected by Golgi membrane trafficking, thus provide a functional link between the PI4,5P2 signaling and Rab-mediated trafficking.
authors.affiliation: Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan; Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo, 102-8472, Japan.
authors.forename: Cuifang
authors.initials: C
authors.lastname: Li
authors.forename: Ayako
authors.initials: A
authors.lastname: Kita
authors.forename: Yuuka
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Misako
authors.initials: M
authors.lastname: Ihara
authors.forename: Ayaka
authors.initials: A
authors.lastname: Kato
authors.forename: Naoya
authors.initials: N
authors.lastname: Ogura
authors.forename: Akira
authors.initials: A
authors.lastname: Doi
authors.forename: Masahide
authors.initials: M
authors.lastname: Oku
authors.forename: Toshiki
authors.initials: T
authors.lastname: Itoh
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Sakai
authors.forename: Reiko
authors.initials: R
authors.lastname: Sugiura
mesh_terms: D000595:Amino Acid Sequence; D011992:Endosomes / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D009154:Mutation; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; C000590732:GYP10 protein, S pombe; D019269:Phosphatidylinositol 4,5-Diphosphate; D029702:Schizosaccharomyces pombe Proteins; C075976:ypt3 protein, S pombe; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; C064392:ryh1 protein, S pombe; D020559:Monomeric GTP-Binding Proteins; D020691:rab GTP-Binding Proteins