title: Mitotic phosphorylation of Golgi reassembly stacking protein 55 by mitogen-activated protein kinase ERK2.
abstract: The role of the mitogen-activated protein kinase kinase (MKK)/extracellular-activated protein kinase (ERK) pathway in mitotic Golgi disassembly is controversial, in part because Golgi-localized targets have not been identified. We observed that Golgi reassembly stacking protein 55 (GRASP55) was phosphorylated in mitotic cells and extracts, generating a mitosis-specific phospho-epitope recognized by the MPM2 mAb. This phosphorylation was prevented by mutation of ERK consensus sites in GRASP55. GRASP55 mitotic phosphorylation was significantly reduced, both in vitro and in vivo, by treatment with U0126, a potent and specific inhibitor of MKK and thus ERK activation. Furthermore, ERK2 directly phosphorylated GRASP55 on the same residues that generated the MPM2 phospho-epitope. These results are the first demonstration of GRASP55 mitotic phosphorylation and indicate that the MKK/ERK pathway directly phosphorylates the Golgi during mitosis.
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Jesch
authors.forename: T S
authors.initials: TS
authors.lastname: Lewis
authors.forename: N G
authors.initials: NG
authors.lastname: Ahn
authors.forename: A D
authors.initials: AD
authors.lastname: Linstedt
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000939:Epitopes; D005982:Glutathione Transferase / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation
chemical_list: D000911:Antibodies, Monoclonal; D002070:Butadienes; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D000939:Epitopes; C122048:GORASP2 protein, human; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D009570:Nitriles; C113580:U 0126; D005982:Glutathione Transferase; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases