title: Endoplasmic reticulum-endosome contact increases as endosomes traffic and mature.
abstract: The endosomal pathway is responsible for plasma membrane cargo uptake, sorting, and, in many cases, lysosome targeting. Endosome maturation is complex, requiring proper spatiotemporal recruitment of factors that regulate the size, maturity, and positioning of endosomal compartments. In animal cells, it also requires trafficking of endosomes on microtubules. Recent work has revealed the presence of contact sites between some endosomes and the endoplasmic reticulum (ER). Although these contact sites are believed to have multiple functions, the frequency, dynamics, and physical attributes of these contacts are poorly understood. Here we use high-resolution three-dimensional electron microscopy to reveal that ER tubules wrap around endosomes and find that both organelles contact microtubules at or near membrane contact sites. As endosomes traffic, they remain bound to the ER, which causes the tubular ER to rearrange its structure around dynamic endosomes at contact sites. Finally, as endosomes transition through steps of maturation, they become more tightly associated with the ER. The major implication of these results is that endosomes mature and traffic while coupled to the ER membrane rather than in isolation.
authors: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
authors: Jonathan R
authors: JR
authors: Friedman
authors: Jared R
authors: JR
authors: Dibenedetto
authors: Matthew
authors: M
authors: West
authors: Ashley A
authors: AA
authors: Rowland
authors: Gia K
authors: GK
authors: Voeltz
mesh_terms: D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D057146:Multivesicular Bodies / Q000378:metabolism / Q000648:ultrastructure; D015739:Nocodazole / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D000069816:SEC Translocation Channels; D059008:Time-Lapse Imaging; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
chemical_list: D008164:Luminescent Proteins; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C499388:SEC61B protein, human; D000090802:rab7 GTP-Binding Proteins; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins; D015739:Nocodazole
references: Traffic. 2011 Jan;12(1):28-41
references: 20955502
references: Nature. 2012 May 23;485(7399):465-70
references: 22622570
references: EMBO J. 1994 Mar 15;13(6):1287-96
references: 8137813
references: Nat Cell Biol. 2010 Mar;12(3):267-72
references: 20118922
references: J Cell Sci. 2009 Jun 15;122(Pt 12):1979-89
references: 19454478
references: Dev Cell. 2007 Sep;13(3):377-90
references: 17765681
references: J Struct Biol. 2005 Oct;152(1):36-51
references: 16182563
references: EMBO J. 2011 Aug 31;30(17):3481-500
references: 21878991
references: PLoS Biol. 2005 Jul;3(7):e233
references: 15954801
references: J Cell Biol. 2011 Apr 18;193(2):333-46
references: 21502358
references: J Microsc. 2007 May;226(Pt 2):182-9
references: 17444947
references: Cell. 2009 Mar 20;136(6):1110-21
references: 19303853
references: Cell. 2004 Feb 6;116(3):445-56
references: 15016378
references: J Cell Biol. 2009 Jun 29;185(7):1209-25
references: 19564404
references: J Cell Biol. 2010 Aug 9;190(3):363-75
references: 20696706
references: Curr Biol. 1998 Jul 2;8(14):798-806
references: 9663388
references: Cell. 2005 Sep 9;122(5):735-49
references: 16143105
references: J Clin Invest. 2002 Jun;109(12):1541-50
references: 12070301
references: Cell. 2010 Apr 30;141(3):497-508
references: 20434987
references: Methods Cell Biol. 2010;96:671-93
references: 20869543
references: Nat Rev Mol Cell Biol. 2009 Aug;10(8):513-25
references: 19603039
references: Trends Cell Biol. 2010 Nov;20(11):672-9
references: 20864346
references: Nat Rev Mol Cell Biol. 2009 Sep;10(9):609-22
references: 19696798
references: Science. 2011 Oct 21;334(6054):358-62
references: 21885730
references: Nat Cell Biol. 1999 Oct;1(6):376-82
references: 10559966
references: Cell. 1988 Jul 1;54(1):37-46
references: 3383243
references: J Struct Biol. 1996 Jan-Feb;116(1):71-6
references: 8742726
references: J Biol Chem. 2008 Jul 4;283(27):18892-904
references: 18442980
references: J Struct Biol. 1997 Dec;120(3):343-52
references: 9441937