title: Mitotic Golgi translocation of ERK1c is mediated by a PI4KIIIβ-14-3-3γ shuttling complex.
abstract: Golgi fragmentation is a highly regulated process that allows division of the Golgi complex between the two daughter cells. The mitotic reorganization of the Golgi is accompanied by a temporary block in Golgi functioning, as protein transport in and out of the Golgi stops. Our group has previously demonstrated the involvement of the alternatively spliced variants ERK1c and MEK1b (ERK1 is also known as MAPK3, and MEK1 as MAP2K1) in mitotic Golgi fragmentation. We had also found that ERK1c translocates to the Golgi at the G2 to M phase transition, but the molecular mechanism underlying this recruitment remains unknown. In this study, we narrowed the translocation timing to prophase and prometaphase, and elucidated its molecular mechanism. We found that CDK1 phosphorylates Ser343 of ERK1c, thereby allowing the binding of phosphorylated ERK1c to a complex that consists of PI4KIIIβ (also known as PI4KB) and the 14-3-3γ dimer (encoded by YWHAB). The stability of the complex is regulated by protein kinase D (PKD)-mediated phosphorylation of PI4KIIIβ. The complex assembly induces the Golgi shuttling of ERK1c, where it is activated by MEK1b, and induces Golgi fragmentation. Our work shows that protein shuttling to the Golgi is not completely abolished at the G2 to M phase transition, thus integrating several independent Golgi-regulating processes into one coherent pathway.
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Inbal
authors.initials: I
authors.lastname: Wortzel
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Hanoch
authors.affiliation: Department of Biological Services, The Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Porat
authors.affiliation: University of Stuttgart, Institute of Cell Biology and Immunology, Stuttgart 70550, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Hausser
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 7610001, Israel Rony.Seger@weizmann.ac.il.
authors.forename: Rony
authors.initials: R
authors.lastname: Seger
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D055503:Protein Multimerization
chemical_list: D048948:14-3-3 Proteins; D048052:Mitogen-Activated Protein Kinase 3; D017853:Phosphotransferases (Alcohol Group Acceptor); C581087:PI4KB protein, human
keywords: CDK1; ERK1c; Golgi fragmentation; Golgi shuttling; PKD