title: PKD controls mitotic Golgi complex fragmentation through a Raf-MEK1 pathway.
abstract: Before entering mitosis, the stacks of the Golgi cisternae are separated from each other, and inhibiting this process delays entry of mammalian cells into mitosis. Protein kinase D (PKD) is known to be involved in Golgi-to-cell surface transport by controlling the biogenesis of specific transport carriers. Here we show that depletion of PKD1 and PKD2 proteins from HeLa cells by small interfering RNA leads to the accumulation of cells in the G2 phase of the cell cycle and prevents cells from entering mitosis. We further provide evidence that inhibition of PKD blocks mitotic Raf-1 and mitogen-activated protein kinase kinase (MEK) activation, and, as a consequence, mitotic Golgi fragmentation, which could be rescued by expression of active MEK1. Finally, Golgi fluorescence recovery after photobleaching analyses demonstrate that PKD is crucial for the cleavage of the noncompact zones of Golgi membranes in G2 phase. Our findings suggest that PKD controls interstack Golgi connections in a Raf-1/MEK1-dependent manner, a process required for entry of the cells into mitosis.
authors.affiliation: Institute of Cell Biology and Immunology, University of Stuttgart, 70569 Stuttgart, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Kienzle
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Eisler
authors.forename: Julien
authors.initials: J
authors.lastname: Villeneuve
authors.forename: Tilman
authors.initials: T
authors.lastname: Brummer
authors.forename: Monilola A
authors.initials: MA
authors.lastname: Olayioye
authors.forename: Angelika
authors.initials: A
authors.lastname: Hausser
mesh_terms: D036681:Fluorescence Recovery After Photobleaching; D059565:G2 Phase Cell Cycle Checkpoints; D055785:Gene Knockdown Techniques; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D008938:Mitosis; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D050396:TRPP Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D048369:MAP Kinase Kinase 1; D019908:Proto-Oncogene Proteins c-raf; D034741:RNA, Small Interfering; D050396:TRPP Cation Channels; C482125:MAP2K1 protein, human