tailieunhanh - Báo cáo khoa học: Passage through the Golgi is necessary for Shiga toxin B subunit to reach the endoplasmic reticulum

Both Shiga holotoxin and the isolated B subunit, navigate a retrograde pathway from the plasma membrane to the endoplasmic reticulum (ER) of mammalian cells to deliver catalytic A subunits into the cytosol. This route passes through early⁄recycling endosomes and then through the Golgi. | ỊFEBS Journal Passage through the Golgi is necessary for Shiga toxin B subunit to reach the endoplasmic reticulum Jenna McKenzie1 Ludger Johannes2 3 Tomohiko Taguchi4 and David Sheff1 1 Department of Pharmacology Carver College of Medicine University of Iowa Iowa City IA USA 2 Institut Curie Centre de Recherche Laboratoire Trafic Signalisation et Ciblage Intracellulaires Paris France 3 CNRS UMR144 Paris France 4 Department of Biochemistry Osaka University Graduate Schoolof Medicine Japan Keywords endosomes Golgi membrane traffic retrograde traffic Shiga toxin Correspondence D. Sheff Department of Pharmacology Carver College of Medicine University of Iowa Iowa City IA 52242-2600 USA Fax 1 319 335 8930 Tel 1 319 335 7705 E-mail david-sheff@ Received 11 November 2008 revised 4 January 2009 accepted 7 January 2009 doi Both Shiga holotoxin and the isolated B subunit navigate a retrograde pathway from the plasma membrane to the endoplasmic reticulum ER of mammalian cells to deliver catalytic A subunits into the cytosol. This route passes through early recycling endosomes and then through the Golgi. Although passage through the endosomes takes only 30 min passage through the Golgi is much slower taking hours. This suggests that Golgi passage is a key step in retrograde traffic. However there is no empirical data demonstrating that Golgi passage is required for the toxins to enter the ER. In fact an alternate pathway bypassing the Golgi is utilized by SV40 virus. Here we find that blocking Shiga toxin B access to the entire Golgi with AlF4 treatment temperature block or subcellular surgery prevented Shiga toxin B from reaching the ER. This suggests that there is no direct endosome to ER route available for retrograde traffic. Curiously when Shiga toxin B was trapped in endosomes it entered the cytosol directly from the endosomal compartment. Our results suggest that trafficking through the Golgi apparatus is required for Shiga .