title: Regulation of secretory transport by protein kinase D-mediated phosphorylation of the ceramide transfer protein.
abstract: Protein kinase D (PKD) has been identified as a crucial regulator of secretory transport at the trans-Golgi network (TGN). Recruitment and activation of PKD at the TGN is mediated by the lipid diacylglycerol, a pool of which is generated by sphingomyelin synthase from ceramide and phosphatidylcholine. The nonvesicular transfer of ceramide from the endoplasmic reticulum to the Golgi complex is mediated by the lipid transfer protein CERT (ceramide transport). In this study, we identify CERT as a novel in vivo PKD substrate. Phosphorylation on serine 132 by PKD decreases the affinity of CERT toward its lipid target phosphatidylinositol 4-phosphate at Golgi membranes and reduces ceramide transfer activity, identifying PKD as a regulator of lipid homeostasis. We also show that CERT, in turn, is critical for PKD activation and PKD-dependent protein cargo transport to the plasma membrane. Thus, the interdependence of PKD and CERT is key to the maintenance of Golgi membrane integrity and secretory transport.
authors.affiliation: University of Stuttgart, Institute of Cell Biology and Immunology, 70569 Stuttgart, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Fugmann
authors.forename: Angelika
authors.initials: A
authors.lastname: Hausser
authors.forename: Patrik
authors.initials: P
authors.lastname: Schöffler
authors.forename: Simone
authors.initials: S
authors.lastname: Schmid
authors.forename: Klaus
authors.initials: K
authors.lastname: Pfizenmaier
authors.forename: Monilola A
authors.initials: MA
authors.lastname: Olayioye
mesh_terms: D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D010957:Plasmids; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D012694:Serine; D005982:Glutathione Transferase; C119090:CERT1 protein, human; C089212:protein kinase D; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C