101
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An Y, Chen CY, Moyer B, Rotkiewicz P, Elsliger MA, Godzik A, Wilson IA, Balch WE. Structural and functional analysis of the globular head domain of p115 provides insight into membrane tethering. J Mol Biol 2009; 391:26-41. [PMID: 19414022 DOI: 10.1016/j.jmb.2009.04.062] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 04/10/2009] [Accepted: 04/15/2009] [Indexed: 01/02/2023]
Abstract
Molecular tethers have a central role in the organization of the complex membrane architecture of eukaryotic cells. p115 is a ubiquitous, essential tether involved in vesicle transport and the structural organization of the exocytic pathway. We describe two crystal structures of the N-terminal domain of p115 at 2.0 A resolution. The p115 structures show a novel alpha-solenoid architecture constructed of 12 armadillo-like, tether-repeat, alpha-helical tripod motifs. We find that the H1 TR binds the Rab1 GTPase involved in endoplasmic reticulum to Golgi transport. Mutation of the H1 motif results in the dominant negative inhibition of endoplasmic reticulum to Golgi trafficking. We propose that the H1 helical tripod contributes to the assembly of Rab-dependent complexes responsible for the tether and SNARE-dependent fusion of membranes.
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Affiliation(s)
- Yu An
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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102
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Recacha R, Boulet A, Jollivet F, Monier S, Houdusse A, Goud B, Khan AR. Structural basis for recruitment of Rab6-interacting protein 1 to Golgi via a RUN domain. Structure 2009; 17:21-30. [PMID: 19141279 DOI: 10.1016/j.str.2008.10.014] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Revised: 10/12/2008] [Accepted: 10/15/2008] [Indexed: 12/31/2022]
Abstract
Small GTPase Rab6 regulates vesicle trafficking at the level of Golgi via recruitment of numerous and unrelated effectors. The crystal structure of Rab6a(GTP) in complex with a 378-residue internal fragment of the effector Rab6IP1 was solved at 3.2 angstroms resolution. This Rab6IP1 region encompasses an all alpha-helical RUN domain followed in tandem by a PLAT domain that adopts a beta sandwich fold. The structure reveals that the first and last alpha helices of the RUN domain mediate binding to switch I, switch II, and the interswitch region of Rab6. It represents the largest Rab-effector complex determined to date. Comparisons with the recent structure of Rab6 in complex with an unrelated effector, human golgin GCC185, reveals significant conformational changes in the conserved hydrophobic triad of Rab6. Flexibility in the switch and interswitch regions of Rab6 mediates recognition of compositionally distinct alpha-helical coiled coils, thereby contributing to Rab6 promiscuity in effector recruitment.
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Affiliation(s)
- Rosario Recacha
- School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland
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103
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Adachi A, Kano F, Saido TC, Murata M. Visual screening and analysis for kinase-regulated membrane trafficking pathways that are involved in extensive β-amyloid secretion. Genes Cells 2009; 14:355-69. [DOI: 10.1111/j.1365-2443.2008.01274.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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104
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Nishimoto-Morita K, Shin HW, Mitsuhashi H, Kitamura M, Zhang Q, Johannes L, Nakayama K. Differential effects of depletion of ARL1 and ARFRP1 on membrane trafficking between the trans-Golgi network and endosomes. J Biol Chem 2009; 284:10583-92. [PMID: 19224922 DOI: 10.1074/jbc.m900847200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ARFRP1 and ARL1, which are both ARF-like small GTPases, are mammalian orthologs of yeast Arl3p and Arl1p, respectively. In yeast, Arl3p targeted to trans-Golgi network (TGN) membranes activates Arl1p, and the activated Arl1p in turn recruits a GRIP domain-containing protein; this complex regulates retrograde transport to the TGN and anterograde transport from the TGN. In the present study, using RNA interference-mediated knockdown of ARFRP1 and ARL1, we have examined whether the orthologs of Arl3p-Arl1p-GRIP story serve similar functions in mammalian cells. However, we have unexpectedly found differential roles of ARL1 and ARFRP1. Specifically, ARL1 and ARFRP1 regulate retrograde transport of Shiga toxin to the TGN and anterograde transport of VSVG from the TGN, respectively. Furthermore, we have obtained evidence suggesting that a SNARE complex containing Vti1a, syntaxin 6, and syntaxin 16 is involved in Shiga toxin transport downstream of ARL1.
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Affiliation(s)
- Kirika Nishimoto-Morita
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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105
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Abstract
Retrograde transport, in which proteins and lipids are shuttled between endosomes and biosynthetic/secretory compartments such as the Golgi apparatus, is crucial for a diverse range of cellular functions. Mechanistic studies that explore the molecular machinery involved in this retrograde trafficking route are shedding light on the functions of transport proteins and are providing fresh insights into possible new therapeutic directions.
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Affiliation(s)
- Ludger Johannes
- CNRS UMR144, Centre de Recherche, Traffic, Signaling, and Delivery Laboratory, 75248 Paris Cedex 05, France.
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106
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Naslavsky N, McKenzie J, Altan-Bonnet N, Sheff D, Caplan S. EHD3 regulates early-endosome-to-Golgi transport and preserves Golgi morphology. J Cell Sci 2009; 122:389-400. [PMID: 19139087 DOI: 10.1242/jcs.037051] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Depletion of EHD3 affects sorting in endosomes by altering the kinetics and route of receptor recycling to the plasma membrane. Here we demonstrate that siRNA knockdown of EHD3, or its interaction partner rabenosyn-5, causes redistribution of sorting nexin 1 (SNX1) to enlarged early endosomes and disrupts transport of internalized Shiga toxin B subunit (STxB) to the Golgi. Moreover, under these conditions, Golgi morphology appears as a series of highly dispersed and fragmented stacks that maintain characteristics of cis-, medial- and trans-Golgi membranes. Although Arf1 still assembled onto these dispersed Golgi membranes, the level of AP-1 gamma-adaptin recruited to the Golgi was diminished. Whereas VSV-G-secretion from the dispersed Golgi remained largely unaffected, the distribution of mannose 6-phosphate receptor (M6PR) was altered: it remained in peripheral endosomes and did not return to the Golgi. Cathepsin D, a hydrolase that is normally transported to lysosomes via an M6PR-dependent pathway, remained trapped at the Golgi. Our findings support a role for EHD3 in regulating endosome-to-Golgi transport, and as a consequence, lysosomal biosynthetic, but not secretory, transport pathways are also affected. These data also suggest that impaired endosome-to-Golgi transport and the resulting lack of recruitment of AP-1 gamma-adaptin to Golgi membranes affect Golgi morphology.
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Affiliation(s)
- Naava Naslavsky
- Department of Biochemistry and Molecular Biology and Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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107
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Hayes GL, Brown FC, Haas AK, Nottingham RM, Barr FA, Pfeffer SR. Multiple Rab GTPase binding sites in GCC185 suggest a model for vesicle tethering at the trans-Golgi. Mol Biol Cell 2009; 20:209-17. [PMID: 18946081 PMCID: PMC2613123 DOI: 10.1091/mbc.e08-07-0740] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/22/2008] [Accepted: 10/14/2008] [Indexed: 12/18/2022] Open
Abstract
GCC185, a trans-Golgi network-localized protein predicted to assume a long, coiled-coil structure, is required for Rab9-dependent recycling of mannose 6-phosphate receptors (MPRs) to the Golgi and for microtubule nucleation at the Golgi via CLASP proteins. GCC185 localizes to the Golgi by cooperative interaction with Rab6 and Arl1 GTPases at adjacent sites near its C terminus. We show here by yeast two-hybrid and direct biochemical tests that GCC185 contains at least four additional binding sites for as many as 14 different Rab GTPases across its entire length. A central coiled-coil domain contains a specific Rab9 binding site, and functional assays indicate that this domain is important for MPR recycling to the Golgi complex. N-Terminal coiled-coils are also required for GCC185 function as determined by plasmid rescue after GCC185 depletion by using small interfering RNA in cultured cells. Golgi-Rab binding sites may permit GCC185 to contribute to stacking and lateral interactions of Golgi cisternae as well as help it function as a vesicle tether.
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Affiliation(s)
- Garret L. Hayes
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Frank C. Brown
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Alexander K. Haas
- Cancer Research Centre, University of Liverpool, Liverpool L9 3AT, United Kingdom
| | - Ryan M. Nottingham
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Francis A. Barr
- Cancer Research Centre, University of Liverpool, Liverpool L9 3AT, United Kingdom
| | - Suzanne R. Pfeffer
- *Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305; and
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108
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Sorting of lysosomal proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:605-14. [PMID: 19046998 DOI: 10.1016/j.bbamcr.2008.10.016] [Citation(s) in RCA: 585] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 10/07/2008] [Accepted: 10/30/2008] [Indexed: 11/24/2022]
Abstract
Lysosomes are composed of soluble and transmembrane proteins that are targeted to lysosomes in a signal-dependent manner. The majority of soluble acid hydrolases are modified with mannose 6-phosphate (M6P) residues, allowing their recognition by M6P receptors in the Golgi complex and ensuing transport to the endosomal/lysosomal system. Other soluble enzymes and non-enzymatic proteins are transported to lysosomes in an M6P-independent manner mediated by alternative receptors such as the lysosomal integral membrane protein LIMP-2 or sortilin. Sorting of cargo receptors and lysosomal transmembrane proteins requires sorting signals present in their cytosolic domains. These signals include dileucine-based motifs, DXXLL or [DE]XXXL[LI], and tyrosine-based motifs, YXXØ, which interact with components of clathrin coats such as GGAs or adaptor protein complexes. In addition, phosphorylation and lipid modifications regulate signal recognition and trafficking of lysosomal membrane proteins. The complex interaction of both luminal and cytosolic signals with recognition proteins guarantees the specific and directed transport of proteins to lysosomes.
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109
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Mucignat-Caretta C, Cavaggioni A, Redaelli M, Malatesta M, Zancanaro C, Caretta A. Selective distribution of protein kinase A regulatory subunit RII{alpha} in rodent gliomas. Neuro Oncol 2008; 10:958-67. [PMID: 18708342 DOI: 10.1215/15228517-2008-054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Differential diagnosis of brain tumor types is mainly based on cell morphology and could benefit from additional markers. The cAMP second-messenger system is involved in regulating cell proliferation and differentiation and is conceivably modulated during cancer transformation. The cAMP second-messenger system mainly activates protein kinases, which are in part docked to cytoskeleton, membranes, or organelles by anchoring proteins, forming protein aggregates that are detergent insoluble and not freely diffusible and that are characteristic for each cell type. The intracellular distribution of the detergent-insoluble regulatory subunits (R) of the cAMP-dependent protein kinase has been examined in mouse and rat glioma cells both in vitro and in vivo by immunohistochemistry. In normal rodent brains, the RIIalpha regulatory subunit is detergent insoluble only in ependymal cells, while in the rest of the brain it is present in soluble form. Immunohistochemistry shows that in both mouse and rat glioma cell lines, RIIalpha is mainly detergent insoluble. RIIalpha is localized close to the nucleus, associated with smooth vesicles in the trans-Golgi network area. Both paclitaxel and vinblastine cause a redistribution of RIIalpha within the cell. Under conditions that increased intracellular cAMP, apoptosis of glioma cells was observed, and it was accompanied by RIIalpha redistribution. Also in vivo, detergent-insoluble RIIalpha can be observed in mouse and rat gliomas, where it delineates the border between normal brain tissue and glioma. Therefore, intracellular distribution of detergent-insoluble RIIalpha can assist in detecting tumor cells within the brain, thus making the histologic diagnosis of brain tumors more accurate, and may represent an additional target for therapy.
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Affiliation(s)
- Carla Mucignat-Caretta
- Department of Human Anatomy and Physiology, University of Padova, Via Marzolo 3, 35131 Padova, Italy.
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110
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Ravikumar B, Imarisio S, Sarkar S, O'Kane CJ, Rubinsztein DC. Rab5 modulates aggregation and toxicity of mutant huntingtin through macroautophagy in cell and fly models of Huntington disease. J Cell Sci 2008; 121:1649-60. [PMID: 18430781 PMCID: PMC2635563 DOI: 10.1242/jcs.025726] [Citation(s) in RCA: 249] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Huntington disease (HD) is caused by a polyglutamine-expansion mutation in huntingtin (HTT) that makes the protein toxic and aggregate-prone. The subcellular localisation of huntingtin and many of its interactors suggest a role in endocytosis, and recently it has been shown that huntingtin interacts indirectly with the early endosomal protein Rab5 through HAP40. Here we show that Rab5 inhibition enhanced polyglutamine toxicity, whereas Rab5 overexpression attenuated toxicity in our cell and fly models of HD. We tried to identify a mechanism for the Rab5 effects in our HD model systems, and our data suggest that Rab5 acts at an early stage of autophagosome formation in a macromolecular complex that contains beclin 1 (BECN1) and Vps34. Interestingly chemical or genetic inhibition of endocytosis also impeded macroautophagy, and enhanced aggregation and toxicity of mutant huntingtin. However, in contrast to Rab5, inhibition of endocytosis by various means suppressed autophagosome-lysosome fusion (the final step in the macroautophagy pathway) similar to bafilomycin A1. Thus, Rab5, which has previously been thought to be exclusively involved in endocytosis, has a new role in macroautophagy. We have previously shown that macroautophagy is an important clearance route for several aggregate-prone proteins including mutant huntingtin. Thus, better understanding of Rab5-regulated autophagy might lead to rational therapeutic targets for HD and other protein-conformation diseases.
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Affiliation(s)
- Brinda Ravikumar
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0XY, UK
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111
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112
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Pérez-Victoria FJ, Mardones GA, Bonifacino JS. Requirement of the human GARP complex for mannose 6-phosphate-receptor-dependent sorting of cathepsin D to lysosomes. Mol Biol Cell 2008; 19:2350-62. [PMID: 18367545 DOI: 10.1091/mbc.e07-11-1189] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The biosynthetic sorting of acid hydrolases to lysosomes relies on transmembrane, mannose 6-phosphate receptors (MPRs) that cycle between the TGN and endosomes. Herein we report that maintenance of this cycling requires the function of the mammalian Golgi-associated retrograde protein (GARP) complex. Depletion of any of the three GARP subunits, Vps52, Vps53, or Vps54, by RNAi impairs sorting of the precursor of the acid hydrolase, cathepsin D, to lysosomes and leads to its secretion into the culture medium. As a consequence, lysosomes become swollen, likely due to a buildup of undegraded materials. Missorting of cathepsin D in GARP-depleted cells results from accumulation of recycling MPRs in a population of light, small vesicles downstream of endosomes. These vesicles might correspond to intermediates in retrograde transport from endosomes to the TGN. Depletion of GARP subunits also blocks the retrograde transport of the TGN protein, TGN46, and the B subunit of Shiga toxin. These observations indicate that the mammalian GARP complex plays a general role in the delivery of retrograde cargo into the TGN. We also report that a Vps54 mutant protein in the Wobbler mouse strain is active in retrograde transport, thus explaining the viability of these mutant mice.
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Affiliation(s)
- F Javier Pérez-Victoria
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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113
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Burguete AS, Fenn TD, Brunger AT, Pfeffer SR. Rab and Arl GTPase family members cooperate in the localization of the golgin GCC185. Cell 2008; 132:286-98. [PMID: 18243103 DOI: 10.1016/j.cell.2007.11.048] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 10/31/2007] [Accepted: 11/26/2007] [Indexed: 10/22/2022]
Abstract
GCC185 is a large coiled-coil protein at the trans Golgi network that is required for receipt of transport vesicles inbound from late endosomes and for anchoring noncentrosomal microtubules that emanate from the Golgi. Here, we demonstrate that recruitment of GCC185 to the Golgi is mediated by two Golgi-localized small GTPases of the Rab and Arl families. GCC185 binds Rab6, and mutation of residues needed for Rab binding abolishes Golgi localization. The crystal structure of Rab6 bound to the GCC185 Rab-binding domain reveals that Rab6 recognizes a two-fold symmetric surface on a coiled coil immediately adjacent to a C-terminal GRIP domain. Unexpectedly, Rab6 binding promotes association of Arl1 with the GRIP domain. We present a structure-derived model for dual GTPase membrane attachment that highlights the potential ability of Rab GTPases to reach binding partners at a significant distance from the membrane via their unstructured and membrane-anchored, hypervariable domains.
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114
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A trans-Golgi network golgin is required for the regulated secretion of TNF in activated macrophages in vivo. Proc Natl Acad Sci U S A 2008; 105:3351-6. [PMID: 18308930 DOI: 10.1073/pnas.0800137105] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transmembrane precursor of tumor necrosis factor-alpha (TNF) exits the trans-Golgi network (TGN) in tubular carriers for subsequent trafficking and delivery to the cell surface; however, the molecular machinery responsible for Golgi export is unknown. We previously reported that members of the TGN golgin family are associated with subdomains and tubules of the TGN. Here, we show that the TGN golgin, p230/golgin-245 (p230), is essential for intracellular trafficking and cell surface delivery of TNF in transfected HeLa cells and activated macrophages. Live-cell imaging revealed that TNF transport from the TGN is mediated selectively by tubules and carriers marked by p230. Significantly, LPS activation of macrophages resulted in a dramatic increase of p230-labeled tubules and carriers emerging from the TGN, indicating that macrophages up-regulate the transport pathway for TNF export. Depletion of p230 in LPS-stimulated macrophages reduced cell surface delivery of TNF by >10-fold compared with control cells. To determine whether p230 depletion blocked TNF secretion in vivo, we generated retrogenic mice expressing a microRNA-vector to silence p230. Bone-marrow stem cells were transduced with recombinant retrovirus containing microRNA constructs and transplanted into irradiated recipients. LPS-activated peritoneal macrophages from p230 miRNA retrogenic mice were depleted of p230 and had dramatically reduced levels of cell surface TNF. Overall, these studies have identified p230 as a key regulator of TNF secretion and have shown that LPS activation of macrophages results in increased Golgi carriers for export. Also, we have demonstrated a previously undescribed approach to control cytokine secretion by the specific silencing of trafficking machinery.
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115
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Ganley IG, Espinosa E, Pfeffer SR. A syntaxin 10-SNARE complex distinguishes two distinct transport routes from endosomes to the trans-Golgi in human cells. ACTA ACUST UNITED AC 2008; 180:159-72. [PMID: 18195106 PMCID: PMC2213607 DOI: 10.1083/jcb.200707136] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mannose 6-phosphate receptors (MPRs) are transported from endosomes to the Golgi after delivering lysosomal enzymes to the endocytic pathway. This process requires Rab9 guanosine triphosphatase (GTPase) and the putative tether GCC185. We show in human cells that a soluble NSF attachment protein receptor (SNARE) complex comprised of syntaxin 10 (STX10), STX16, Vti1a, and VAMP3 is required for this MPR transport but not for the STX6-dependent transport of TGN46 or cholera toxin from early endosomes to the Golgi. Depletion of STX10 leads to MPR missorting and hypersecretion of hexosaminidase. Mouse and rat cells lack STX10 and, thus, must use a different target membrane SNARE for this process. GCC185 binds directly to STX16 and is competed by Rab6. These data support a model in which the GCC185 tether helps Rab9-bearing transport vesicles deliver their cargo to the trans-Golgi and suggest that Rab GTPases can regulate SNARE–tether interactions. Importantly, our data provide a clear molecular distinction between the transport of MPRs and TGN46 to the trans-Golgi.
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Affiliation(s)
- Ian G Ganley
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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116
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McKenzie J, Johannes L, Taguchi T, Sheff D. Passage through the Golgi is necessary for Shiga toxin B subunit to reach the endoplasmic reticulum. FEBS J 2008; 276:1581-95. [PMID: 19220458 DOI: 10.1111/j.1742-4658.2009.06890.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
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 AlF(4)(-) 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 toxin B to reach the ER and that diversion into the Golgi may prevent toxin escape from endosomes into the cytosol.
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Affiliation(s)
- Jenna McKenzie
- Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-2600, USA
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117
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Lieu ZZ, Derby MC, Teasdale RD, Hart C, Gunn P, Gleeson PA. The golgin GCC88 is required for efficient retrograde transport of cargo from the early endosomes to the trans-Golgi network. Mol Biol Cell 2007; 18:4979-91. [PMID: 17914056 PMCID: PMC2096601 DOI: 10.1091/mbc.e07-06-0622] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Retrograde transport pathways from early/recycling endosomes to the trans-Golgi network (TGN) are poorly defined. We have investigated the role of TGN golgins in retrograde trafficking. Of the four TGN golgins, p230/golgin-245, golgin-97, GCC185, and GCC88, we show that GCC88 defines a retrograde transport pathway from early endosomes to the TGN. Depletion of GCC88 in HeLa cells by interference RNA resulted in a block in plasma membrane-TGN recycling of two cargo proteins, TGN38 and a CD8 mannose-6-phosphate receptor cytoplasmic tail fusion protein. In GCC88-depleted cells, cargo recycling was blocked in the early endosome. Depletion of GCC88 dramatically altered the TGN localization of the t-SNARE syntaxin 6, a syntaxin required for endosome to TGN transport. Furthermore, the transport block in GCC88-depleted cells was rescued by syntaxin 6 overexpression. Internalized Shiga toxin was efficiently transported from endosomes to the Golgi of GCC88-depleted cells, indicating that Shiga toxin and TGN38 are internalized by distinct retrograde transport pathways. These findings have identified an essential role for GCC88 in the localization of TGN fusion machinery for transport from early endosomes to the TGN, and they have allowed the identification of a retrograde pathway which differentially selects TGN38 and mannose-6-phosphate receptor from Shiga toxin.
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Affiliation(s)
- Zi Zhao Lieu
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Merran C. Derby
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Rohan D. Teasdale
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Charles Hart
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Priscilla Gunn
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
| | - Paul A. Gleeson
- *The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia; and
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