title: Sar1 translocation onto the ER-membrane for vesicle budding has different pathways for promotion and suppression of ER-to-Golgi transport mediated through H89-sensitive kinase and ER-resident G protein.
abstract: ER-to-Golgi protein transport involves transport vesicles of which formation is initiated by assembly of Sar1. The assembly of Sar1 is suppressed by protein kinase inhibitor H89, suggesting that ER-to-Golgi transport is regulated progressively by H89 sensitive kinase. ER-resident G(i2) protein suppresses vesicle formation with inhibition of Sar1 assembly. This study examined whether these promotion and suppression of vesicle transport share the same signal pathway, by examining the effects of G(i/o) protein activator mastoparan 7 (Mp-7) and H89 on Sar1 and Sec23 recruitment onto microsomes. In a cell-free system for Sar1 translocation assay, GTPγS addition induced the translocation of Sar1 onto microsomes. Mp-7 and H89 decreased the Sar1 translocation. Double treatment of Mp-7 and H89 strongly decreased Sar1 translocation. In single and double treatments, however, G(i/o) protein inactivator pertussis toxin (IAP) partially restored the suppressive effect of Mp-7, but had not any effect on H89-induced effect. Then, the assembly of Sec23 onto the microsome was also increased by the addition of GTPγS. Sec23 translocation was decreased by Mp-7 and/or H89 treatment and recovered by IAP pretreatment except for H89 single treatment, similarly to Sar1 translocation in each treatment. Inhibitory effects of H89 and Mp-7on ER-to-Golgi vesicle transport by H89 or Mp-7 were also confirmed in a cell culture system by BFA-dispersion and BFA-reconstruction experiments. These findings indicate that promotion and suppression of ER-to-Golgi vesicle transport are modulated through separate signal pathways.
authors.affiliation: Laboratory of Toxicology, Course of Veterinary Science, Graduate School of Life and Environmental Biosciences, Osaka Prefecture University, 1-58, Rinku-Ourai-Kita, Izumisano 598-8531, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Masakazu
authors.initials: M
authors.lastname: Ishizaki
authors.forename: Shuichi
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Takuto
authors.initials: T
authors.lastname: Abe
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nishimura
authors.forename: Masayuki
authors.initials: M
authors.lastname: Komori
authors.forename: Saburo
authors.initials: S
authors.lastname: Matsuo
mesh_terms: D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002474:Cell-Free System; D002478:Cells, Cultured; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D007425:Intracellular Membranes / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D008099:Liver / Q000166:cytology; D008297:Male; D008861:Microsomes / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D007546:Isoquinolines; C084070:Mas7 protein, synthetic; D010455:Peptides; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors; D013449:Sulfonamides; D033921:Vesicular Transport Proteins; D020126:Brefeldin A; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D037342:Pertussis Toxin; D011494:Protein Kinases; C487879:SAR1 protein, rat; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020559:Monomeric GTP-Binding Proteins; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide