title: Protein kinase Cdelta is activated by Shiga toxin and regulates its transport.
abstract: Protein kinase C (PKC) isozymes regulate different vesicular trafficking steps in the recycling or degradative pathways. However, a possible role of these kinases in the retrograde pathway from endosomes to the Golgi complex has previously not been investigated. We report here the involvement of a specific PKC isozyme, PKCdelta, in the intracellular transport of the glycolipid-binding Shiga toxin (Stx), which utilizes the retrograde pathway to intoxicate cells. Upon binding to cells, Stx was shown to specifically activate PKCdelta and not PKCalpha. The involvement of PKCdelta and PKCalpha in the retrograde transport of Stx was then monitored biochemically and by immunofluorescence after inhibition or depletion of the isozymes. PKCdelta, but not PKCalpha, was shown to selectively regulate the endosome-to-Golgi transport of StxB. Upon inhibition or knockdown of PKCdelta, StxB molecules colocalized less with giantin and more with EEA1, indicating that the molecules were accumulated in endosomes, unable to reach the Golgi complex. The inhibition of Golgi transport of Stx was reflected by a strong reduction in the toxic effect, demonstrating that transport of Stx to the cytosol is dependent on PKCdelta activity. These results are in agreement with our previous data, which show that Stx is able to stimulate its own transport.
authors.affiliation: Institute for Cancer Research, Faculty Division, The Norwegian Radium Hospital, University of Oslo, Montebello, 0310 Oslo, Norway.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Torgersen
authors.forename: Sébastien
authors.initials: S
authors.lastname: Wälchli
authors.forename: Stine
authors.initials: S
authors.lastname: Grimmer
authors.forename: Sigrid S
authors.initials: SS
authors.lastname: Skånland
authors.forename: Kirsten
authors.initials: K
authors.lastname: Sandvig
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D011992:Endosomes / Q000201:enzymology*; D004789:Enzyme Activation; D006056:Golgi Apparatus / Q000201:enzymology*; D000077614:Golgi Matrix Proteins; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D011485:Protein Binding; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000378:metabolism*; D021381:Protein Transport; D022621:Shiga Toxin / Q000378:metabolism*; D014709:Vero Cells; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D000077614:Golgi Matrix Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C087574:macrogolgin; D022621:Shiga Toxin; C497258:PRKCD protein, human; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta