51
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Fjorback AW, Andersen OM. SorLA is a molecular link for retromer-dependent sorting of the Amyloid precursor protein. Commun Integr Biol 2013; 5:616-9. [PMID: 23740096 PMCID: PMC3541330 DOI: 10.4161/cib.21433] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Deficiency in the retromer sorting pathway is known to be associated with the onset of Alzheimer disease (AD), and has been suggested to involve regulation of Amyloid precursor protein (APP) trafficking. Absence of the APP sorting receptor sorLA is also associated to AD, as amyloidogenic processing of APP is increased due to missorting. Reduced activity of either retromer or sorLA thus both lead to enhanced amyloidogenic APP processing, and these pathways are therefore important factors for understanding the development of AD. It is therefore key to outline the neuronal APP trafficking in order to determine the mechanisms that influence AD onset.
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Affiliation(s)
- Anja W Fjorback
- Department of Biomedicine, Health; Aarhus University; Denmark
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52
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Genome-wide siRNA screen identifies the retromer as a cellular entry factor for human papillomavirus. Proc Natl Acad Sci U S A 2013; 110:7452-7. [PMID: 23569269 DOI: 10.1073/pnas.1302164110] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite major advances in our understanding of many aspects of human papillomavirus (HPV) biology, HPV entry is poorly understood. To identify cellular genes required for HPV entry, we conducted a genome-wide screen for siRNAs that inhibited infection of HeLa cells by HPV16 pseudovirus. Many retrograde transport factors were required for efficient infection, including multiple subunits of the retromer, which initiates retrograde transport from the endosome to the trans-Golgi network (TGN). The retromer has not been previously implicated in virus entry. Furthermore, HPV16 capsid proteins arrive in the TGN/Golgi in a retromer-dependent fashion during entry, and incoming HPV proteins form a stable complex with retromer subunits. We propose that HPV16 directly engages the retromer at the early or late endosome and traffics to the TGN/Golgi via the retrograde pathway during cell entry. These results provide important insights into HPV entry, identify numerous potential antiviral targets, and suggest that the role of the retromer in infection by other viruses should be assessed.
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53
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Zelazny E, Santambrogio M, Pourcher M, Chambrier P, Berne-Dedieu A, Fobis-Loisy I, Miège C, Jaillais Y, Gaude T. Mechanisms governing the endosomal membrane recruitment of the core retromer in Arabidopsis. J Biol Chem 2013; 288:8815-25. [PMID: 23362252 DOI: 10.1074/jbc.m112.440503] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The retromer complex localizes to endosomal membranes and is involved in protein trafficking. In mammals, it is composed of a dimer of sorting nexins and of the core retromer consisting of vacuolar protein sorting (VPS)26, VPS29, and VPS35. Although homologs of these proteins have been identified in plants, how the plant retromer functions remains elusive. To better understand the role of VPS components in the assembly and function of the core retromer, we characterize here Arabidopsis vps26-null mutants. We show that impaired VPS26 function has a dramatic effect on VPS35 levels and causes severe phenotypic defects similar to those observed in vps29-null mutants. This implies that functions of plant VPS26, VPS29, and VPS35 are tightly linked. Then, by combining live-cell imaging with immunochemical and genetic approaches, we report that VPS35 alone is able to bind to endosomal membranes and plays an essential role in VPS26 and VPS29 membrane recruitment. We also show that the Arabidopsis Rab7 homolog RABG3f participates in the recruitment of the core retromer to the endosomal membrane by interacting with VPS35. Altogether our data provide original information on the molecular interactions that mediate assembly of the core retromer in plants.
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Affiliation(s)
- Enric Zelazny
- CNRS, F-69342 Lyon, France, the Institut National de la Recherche Agronomique, F-69364 Lyon, France
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54
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Willnow TE, Andersen OM. Sorting receptor SORLA – a trafficking path to avoid Alzheimer disease. J Cell Sci 2013; 126:2751-60. [DOI: 10.1242/jcs.125393] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Excessive proteolytic breakdown of the amyloid precursor protein (APP) to neurotoxic amyloid β peptides (Aβ) by secretases in the brain is a molecular cause of Alzheimer disease (AD). According to current concepts, the complex route whereby APP moves between the secretory compartment, the cell surface and endosomes to encounter the various secretases determines its processing fate. However, the molecular mechanisms that control the intracellular trafficking of APP in neurons and their contribution to AD remain poorly understood. Here, we describe the functional elucidation of a new sorting receptor SORLA that emerges as a central regulator of trafficking and processing of APP. SORLA interacts with distinct sets of cytosolic adaptors for anterograde and retrograde movement of APP between the trans-Golgi network and early endosomes, thereby restricting delivery of the precursor to endocytic compartments that favor amyloidogenic breakdown. Defects in SORLA and its interacting adaptors result in transport defects and enhanced amyloidogenic processing of APP, and represent important risk factors for AD in patients. As discussed here, these findings uncovered a unique regulatory pathway for the control of neuronal protein transport, and provide clues as to why defects in this pathway cause neurodegenerative disease.
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55
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Kang H, Kim SY, Song K, Sohn EJ, Lee Y, Lee DW, Hara-Nishimura I, Hwang I. Trafficking of vacuolar proteins: the crucial role of Arabidopsis vacuolar protein sorting 29 in recycling vacuolar sorting receptor. THE PLANT CELL 2012; 24:5058-73. [PMID: 23263768 PMCID: PMC3556975 DOI: 10.1105/tpc.112.103481] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 11/26/2012] [Accepted: 12/06/2012] [Indexed: 05/18/2023]
Abstract
The retromer is involved in recycling lysosomal sorting receptors in mammals. A component of the retromer complex in Arabidopsis thaliana, vacuolar protein sorting 29 (VPS29), plays a crucial role in trafficking storage proteins to protein storage vacuoles. However, it is not known whether or how vacuolar sorting receptors (VSRs) are recycled from the prevacuolar compartment (PVC) to the trans-Golgi network (TGN) during trafficking to the lytic vacuole (LV). Here, we report that VPS29 plays an essential role in the trafficking of soluble proteins to the LV from the TGN to the PVC. maigo1-1 (mag1-1) mutants, which harbor a knockdown mutation in VPS29, were defective in trafficking of two soluble proteins, Arabidopsis aleurain-like protein (AALP):green fluorescent protein (GFP) and sporamin:GFP, to the LV but not in trafficking membrane proteins to the LV or plasma membrane or via the secretory pathway. AALP:GFP and sporamin:GFP in mag1-1 protoplasts accumulated in the TGN but were also secreted into the medium. In mag1-1 mutants, VSR1 failed to recycle from the PVC to the TGN; rather, a significant proportion was transported to the LV; VSR1 overexpression rescued this defect. Moreover, endogenous VSRs were expressed at higher levels in mag1-1 plants. Based on these results, we propose that VPS29 plays a crucial role in recycling VSRs from the PVC to the TGN during the trafficking of soluble proteins to the LV.
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Affiliation(s)
- Hyangju Kang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Soo Youn Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyungyoung Song
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Eun Ju Sohn
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Yongjik Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Dong Wook Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Ikuko Hara-Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Inhwan Hwang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
- Address correspondence to
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56
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Abstract
The retromer complex is a vital element of the endosomal protein sorting machinery that is conserved across all eukaryotes. Retromer is most closely associated with the endosome-to-Golgi retrieval pathway and is necessary to maintain an active pool of hydrolase receptors in the trans-Golgi network. Recent progress in studies of retromer have identified new retromer-interacting proteins, including the WASH complex and cargo such as the Wntless/MIG-14 protein, which now extends the role of retromer beyond the endosome-to-Golgi pathway and has revealed that retromer is required for aspects of endosome-to-plasma membrane sorting and regulation of signalling events. The interactions between the retromer complex and other macromolecular protein complexes now show how endosomal protein sorting is coordinated with actin assembly and movement along microtubules, and place retromer squarely at the centre of a complex set of protein machinery that governs endosomal protein sorting. Dysregulation of retromer-mediated endosomal protein sorting leads to various pathologies, including neurodegenerative diseases such as Alzheimer disease and spastic paraplegia and the mechanisms underlying these pathologies are starting to be understood. In this Commentary, I will highlight recent advances in the understanding of retromer-mediated endosomal protein sorting and discuss how retromer contributes to a diverse set of physiological processes.
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57
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Gross JC, Chaudhary V, Bartscherer K, Boutros M. Active Wnt proteins are secreted on exosomes. Nat Cell Biol 2012; 14:1036-45. [PMID: 22983114 DOI: 10.1038/ncb2574] [Citation(s) in RCA: 725] [Impact Index Per Article: 60.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 08/08/2012] [Indexed: 12/16/2022]
Abstract
Wnt signalling has important roles during development and in many diseases. As morphogens, hydrophobic Wnt proteins exert their function over a distance to induce patterning and cell differentiation decisions. Recent studies have identified several factors that are required for the secretion of Wnt proteins; however, how Wnts travel in the extracellular space remains a largely unresolved question. Here we show that Wnts are secreted on exosomes both during Drosophila development and in human cells. We demonstrate that exosomes carry Wnts on their surface to induce Wnt signalling activity in target cells. Together with the cargo receptor Evi/WIs, Wnts are transported through endosomal compartments onto exosomes, a process that requires the R-SNARE Ykt6. Our study demonstrates an evolutionarily conserved functional role of extracellular vesicular transport of Wnt proteins.
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Affiliation(s)
- Julia Christina Gross
- German Cancer Research Center (DKFZ), Division Signaling and Functional Genomics and Heidelberg University, Department for Cell and Molecular Biology, Medical Faculty Mannheim, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
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58
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Cuartero Y, Mellado M, Capell A, Álvarez-Dolado M, Verges M. Retromer Regulates Postendocytic Sorting of β-Secretase in Polarized Madin-Darby Canine Kidney Cells. Traffic 2012; 13:1393-410. [DOI: 10.1111/j.1600-0854.2012.01392.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 06/28/2012] [Accepted: 07/03/2012] [Indexed: 01/24/2023]
Affiliation(s)
- Yasmina Cuartero
- Laboratory of Epithelial Cell Biology; Centro de Investigación Príncipe Felipe; Valencia; Spain
| | - Maravillas Mellado
- Laboratory of Epithelial Cell Biology; Centro de Investigación Príncipe Felipe; Valencia; Spain
| | - Anja Capell
- German Center for Neurodegenerative Diseases & Adolf Butenandt Institute - Biochemistry; Ludwig Maximilians University; Munich; Germany
| | - Manuel Álvarez-Dolado
- Department of Cell Therapy and Regenerative Medicine; Andalusian Center for Molecular Biology and Regenerative Medicine; Seville; Spain
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59
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Robinson DG, Pimpl P, Scheuring D, Stierhof YD, Sturm S, Viotti C. Trying to make sense of retromer. TRENDS IN PLANT SCIENCE 2012; 17:431-9. [PMID: 22502774 DOI: 10.1016/j.tplants.2012.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/13/2012] [Accepted: 03/15/2012] [Indexed: 05/08/2023]
Abstract
Retromer is a cytosolic protein complex which binds to post-Golgi organelles involved in the trafficking of proteins to the lytic compartment of the cell. In non-plant organisms, retromer mediates the recycling of acid hydrolase receptors from early endosomal (EE) compartments. In plants, retromer components are required for the targeting of vacuolar storage proteins, and for the recycling of endocytosed PIN proteins. However, there are contradictory reports as to the localization of the sorting nexins and the core subunit of retromer. There is also uncertainty as to the identity of the organelles from which vacuolar sorting receptors (VSRs) and endocytosed plasma membrane (PM) proteins are recycled. In this review we try to resolve some of these conflicting observations.
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Affiliation(s)
- David G Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
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60
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Liu TT, Gomez TS, Sackey BK, Billadeau DD, Burd CG. Rab GTPase regulation of retromer-mediated cargo export during endosome maturation. Mol Biol Cell 2012; 23:2505-15. [PMID: 22593205 PMCID: PMC3386214 DOI: 10.1091/mbc.e11-11-0915] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 04/25/2012] [Accepted: 05/07/2012] [Indexed: 11/11/2022] Open
Abstract
The retromer complex, composed of sorting nexin subunits and a Vps26/Vps29/Vps35 trimer, mediates sorting of retrograde cargo from the endosome to the trans-Golgi network. The retromer trimer subcomplex is an effector of Rab7 (Ypt7 in yeast). Whereas endosome targeting of human retromer has been shown to require Rab7-GTP, targeting of yeast retromer to the endosome is independent of Ypt7-GTP and requires the Vps5 and Vps17 retromer sorting nexin subunits. An evolutionarily conserved amino acid segment within Vps35 is required for Ypt7/Rab7 recognition in vivo by both yeast and human retromer, establishing that Rab recognition is a conserved feature of this subunit. Recognition of Ypt7 by retromer is required for its function in retrograde sorting, and in yeast cells lacking the guanine nucleotide exchange factor for Ypt7, retrograde cargo accumulates in endosomes that are decorated with retromer, revealing an additional role for Rab recognition at the cargo export stage of the retromer functional cycle. In addition, yeast retromer trimer antagonizes Ypt7-regulated organelle tethering and fusion of endosomes/vacuoles via recognition of Ypt7. Thus retromer has dual roles in retrograde cargo export and in controlling the fusion dynamics of the late endovacuolar system.
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Affiliation(s)
- Ting-Ting Liu
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Timothy S. Gomez
- Department of Immunology, Division of Oncology Research and Schulze Center for Novel Therapeutics, College of Medicine, Mayo Clinic, Rochester, MN 55905
| | - Bridget K. Sackey
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Daniel D. Billadeau
- Department of Immunology, Division of Oncology Research and Schulze Center for Novel Therapeutics, College of Medicine, Mayo Clinic, Rochester, MN 55905
| | - Christopher G. Burd
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
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61
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De Marcos Lousa C, Gershlick DC, Denecke J. Mechanisms and concepts paving the way towards a complete transport cycle of plant vacuolar sorting receptors. THE PLANT CELL 2012; 24:1714-32. [PMID: 22570446 PMCID: PMC3442565 DOI: 10.1105/tpc.112.095679] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Delivery of proteins to the lytic vacuole in plants is a complex cascade of selective interactions that specifically excludes residents of the endoplasmic reticulum and secreted proteins. Vacuolar transport must be highly efficient to avoid mistargeting of hydrolytic enzymes to locations where they could be harmful. While plant vacuolar sorting signals have been well described for two decades, it is only during the last 5 years that a critical mass of data was gathered that begins to reveal how vacuolar sorting receptors (VSRs) may complete a full transport cycle. Yet, the field is far from reaching a consensus regarding the organelles that could be involved in vacuolar sorting, their potential biogenesis, and the ultimate recycling of membranes and protein machinery that maintain this pathway. This review will highlight the important landmarks in our understanding of VSR function and compare recent transport models that have been proposed so that an emerging picture of plant vacuolar sorting mechanisms can be drawn.
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62
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Finnigan GC, Cronan GE, Park HJ, Srinivasan S, Quiocho FA, Stevens TH. Sorting of the yeast vacuolar-type, proton-translocating ATPase enzyme complex (V-ATPase): identification of a necessary and sufficient Golgi/endosomal retention signal in Stv1p. J Biol Chem 2012; 287:19487-500. [PMID: 22496448 DOI: 10.1074/jbc.m112.343814] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit a of the yeast vacuolar-type, proton-translocating ATPase enzyme complex (V-ATPase) is responsible for both proton translocation and subcellular localization of this highly conserved molecular machine. Inclusion of the Vph1p isoform causes the V-ATPase complex to traffic to the vacuolar membrane, whereas incorporation of Stv1p causes continued cycling between the trans-Golgi and endosome. We previously demonstrated that this targeting information is contained within the cytosolic, N-terminal portion of V-ATPase subunit a (Stv1p). To identify residues responsible for sorting of the Golgi isoform of the V-ATPase, a random mutagenesis was performed on the N terminus of Stv1p. Subsequent characterization of mutant alleles led to the identification of a short peptide sequence, W(83)KY, that is necessary for proper Stv1p localization. Based on three-dimensional homology modeling to the Meiothermus ruber subunit I, we propose a structural model of the intact Stv1p-containing V-ATPase demonstrating the accessibility of the W(83)KY sequence to retrograde sorting machinery. Finally, we characterized the sorting signal within the context of a reconstructed Stv1p ancestor (Anc.Stv1). This evolutionary intermediate includes an endogenous W(83)KY sorting motif and is sufficient to compete with sorting of the native yeast Stv1p V-ATPase isoform. These data define a novel sorting signal that is both necessary and sufficient for trafficking of the V-ATPase within the Golgi/endosomal network.
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Affiliation(s)
- Gregory C Finnigan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
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63
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Recruitment of the endosomal WASH complex is mediated by the extended 'tail' of Fam21 binding to the retromer protein Vps35. Biochem J 2012; 442:209-20. [PMID: 22070227 DOI: 10.1042/bj20111761] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The retromer complex is a conserved endosomal protein sorting complex that sorts membrane proteins into nascent endosomal tubules. The recognition of membrane proteins is mediated by the cargo-selective retromer complex, a stable trimer of the Vps35 (vacuolar protein sorting 35), Vps29 and Vps26 proteins. We have recently reported that the cargo-selective retromer complex associates with the WASH (Wiskott-Aldrich syndrome homologue) complex, a multimeric protein complex that regulates tubule dynamics at endosomes. In the present study, we show that the retromer-WASH complex interaction occurs through the long unstructured 'tail' domain of the WASH complex-Fam21 protein binding to Vps35, an interaction that is necessary and sufficient to target the WASH complex to endosomes. The Fam21-tail also binds to FKBP15 (FK506-binding protein 15), a protein associated with ulcerative colitis, to mediate the membrane association of FKBP15. Elevated Fam21-tail expression inhibits the association of the WASH complex with retromer, resulting in increased cytoplasmic WASH complex. Additionally, overexpression of the Fam21-tail results in cell-spreading defects, implicating the activity of the WASH complex in regulating the mobilization of membrane into the endosome-to-cell surface pathway.
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64
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Retromer binds the FANSHY sorting motif in SorLA to regulate amyloid precursor protein sorting and processing. J Neurosci 2012; 32:1467-80. [PMID: 22279231 DOI: 10.1523/jneurosci.2272-11.2012] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
sorLA is a sorting receptor for amyloid precursor protein (APP) genetically linked to Alzheimer's disease (AD). Retromer, an adaptor complex in the endosome-to-Golgi retrieval pathway, has been implicated in APP transport because retromer deficiency leads to aberrant APP sorting and processing and levels of retromer proteins are altered in AD. Here we report that sorLA and retromer functionally interact in neurons to control trafficking and amyloidogenic processing of APP. We have identified a sequence (FANSHY) in the cytoplasmic domain of sorLA that is recognized by the VPS26 subunit of the retromer complex. Accordingly, we characterized the interaction between the retromer complex and sorLA and determined the role of retromer on sorLA-dependent sorting and processing of APP. Mutations in the VPS26 binding site resulted in receptor redistribution to the endosomal network, similar to the situation seen in cells with VPS26 knockdown. The sorLA mutant retained APP-binding activity but, as opposed to the wild-type receptor, misdirected APP into a distinct non-Golgi compartment, resulting in increased amyloid processing. In conclusion, our data provide a molecular link between reduced retromer expression and increased amyloidogenesis as seen in patients with sporadic AD.
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65
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Cullen PJ, Korswagen HC. Sorting nexins provide diversity for retromer-dependent trafficking events. Nat Cell Biol 2011; 14:29-37. [PMID: 22193161 PMCID: PMC3613977 DOI: 10.1038/ncb2374] [Citation(s) in RCA: 265] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sorting nexins are a large family of evolutionarily conserved phosphoinositide-binding proteins that have fundamental roles in orchestrating cargo sorting through the membranous maze that is the endosomal network. One ancient group of complexes that contain sorting nexins is the retromer. Here we discuss how retromer complexes regulate endosomal sorting, and describe how this is generating exciting new insight into the central role played by endosomal sorting in development and homeostasis of normal tissues.
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Affiliation(s)
- Peter J. Cullen
- Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, U.K
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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66
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McLeod IX, Zhou X, Li QJ, Wang F, He YW. The class III kinase Vps34 promotes T lymphocyte survival through regulating IL-7Rα surface expression. THE JOURNAL OF IMMUNOLOGY 2011; 187:5051-61. [PMID: 22021616 DOI: 10.4049/jimmunol.1100710] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IL-7Rα-mediated signals are essential for naive T lymphocyte survival. Recent studies show that IL-7Rα is internalized and either recycled to cell surface or degraded. However, how the intracellular process of IL-7Rα trafficking is regulated is unclear. In this paper, we show that Vps34, the class III PI3K, plays a critical role in proper IL-7Rα intracellular trafficking. Mice lacking Vps34 in T lymphocytes had a severely reduced T lymphocyte compartment. Vps34-deficient T lymphocytes exhibit increased death and reduced IL-7Rα surface expression, although three major forms of autophagy remain intact. Intracellular IL-7Rα in normal T lymphocytes at steady state is trafficked through either early endosome/multivesicular bodies to the late endosome-Golgi for surface expression or to the lysosome for degradation. However, Vps34-deficient T cells have mislocalized intracellular Eea1, HGF-regulated tyrosine kinase substrate, and Vps36 protein levels, the combined consequence of which is the inability to mobilize internalized IL-7Rα into the retromer pathway for surface display. Our studies reveal that Vps34, though dispensable for autophagy induction, is a critical regulator of naive T cell homeostasis, modulating IL-7Rα trafficking, signaling, and recycling.
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Affiliation(s)
- Ian X McLeod
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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67
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Kingston D, Chang H, Ensser A, Lee HR, Lee J, Lee SH, Jung JU, Cho NH. Inhibition of retromer activity by herpesvirus saimiri tip leads to CD4 downregulation and efficient T cell transformation. J Virol 2011; 85:10627-38. [PMID: 21849449 PMCID: PMC3187508 DOI: 10.1128/jvi.00757-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 08/08/2011] [Indexed: 11/20/2022] Open
Abstract
The mammalian retromer is an evolutionally conserved protein complex composed of a vacuolar protein sorting trimer (Vps 26/29/35) that participates in cargo recognition and a sorting nexin (SNX) dimer that binds to endosomal membranes. The retromer plays an important role in efficient retrograde transport for endosome-to-Golgi retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR), a receptor for lysosomal hydrolases, and other endosomal proteins. This ultimately contributes to the control of cell growth, cell adhesion, and cell migration. The herpesvirus saimiri (HVS) tyrosine kinase-interacting protein (Tip), required for the immortalization of primary T lymphocytes, targets cellular signaling molecules, including Lck tyrosine kinases and the p80 endosomal trafficking protein. Despite the pronounced effects of HVS Tip on T cell signal transduction, the details of its activity on T cell immortalization remain elusive. Here, we report that the amino-terminal conserved, glutamate-rich sequence of Tip specifically interacts with the retromer subunit Vps35 and that this interaction not only causes the redistribution of Vps35 from the early endosome to the lysosome but also drastically inhibits retromer activity, as measured by decreased levels of CI-MPR and lower activities of cellular lysosomal hydrolases. Physiologically, the inhibition of intracellular retromer activity by Tip is ultimately linked to the downregulation of CD4 surface expression and to the efficient in vitro immortalization of primary human T cells to interleukin-2 (IL-2)-independent permanent growth. Therefore, HVS Tip uniquely targets the retromer complex to impair the intracellular trafficking functions of infected cells, ultimately contributing to efficient T cell transformation.
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Affiliation(s)
- Dior Kingston
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Institute for Research in Biomedicine, Via Vincenzo Vela 6, 6500 Bellinzona, Switzerland
| | - Heesoon Chang
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Molecular Microbiology & Immunology, University of Southern California, School of Medicine, 2011 Zonal Avenue, HMR401, Los Angeles, California 90033
| | - Armin Ensser
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91054 Erlangen, Germany
| | - Hye-Ra Lee
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Molecular Microbiology & Immunology, University of Southern California, School of Medicine, 2011 Zonal Avenue, HMR401, Los Angeles, California 90033
| | - Jongsoo Lee
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Molecular Microbiology & Immunology, University of Southern California, School of Medicine, 2011 Zonal Avenue, HMR401, Los Angeles, California 90033
| | - Sun-Hwa Lee
- Molecular Microbiology & Immunology, University of Southern California, School of Medicine, 2011 Zonal Avenue, HMR401, Los Angeles, California 90033
| | - Jae Ung Jung
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Molecular Microbiology & Immunology, University of Southern California, School of Medicine, 2011 Zonal Avenue, HMR401, Los Angeles, California 90033
| | - Nam-Hyuk Cho
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772-9102
- Department of Microbiology and Immunology, Seoul National University College of Medicine, and Institute of Endemic Disease, Seoul National University Medical Research Center and Bundang Hospital, Jongno-Gu, Seoul 110-799, Republic of Korea
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68
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Koumandou VL, Klute MJ, Herman EK, Nunez-Miguel R, Dacks JB, Field MC. Evolutionary reconstruction of the retromer complex and its function in Trypanosoma brucei. J Cell Sci 2011; 124:1496-509. [PMID: 21502137 DOI: 10.1242/jcs.081596] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Intracellular trafficking and protein sorting are mediated by various protein complexes, with the retromer complex being primarily involved in retrograde traffic from the endosome or lysosome to the Golgi complex. Here, comparative genomics, cell biology and phylogenetics were used to probe the early evolution of retromer and its function. Retromer subunits Vps26, Vps29 and Vps35 are near universal, and, by inference, the complex was an ancient feature of eukaryotic cells. Surprisingly, we found DSCR3, a Vps26 paralogue in humans associated with Down's syndrome, in at least four eukaryotic supergroups, implying a more ancient origin than previously suspected. By contrast, retromer cargo proteins showed considerable interlineage variability, with lineage-specific and broadly conserved examples found. Vps10 trafficking probably represents an ancestral role for the complex. Vps5, the BAR-domain-containing membrane-deformation subunit, was found in diverse eukaryotes, including in the divergent eukaryote Trypanosoma brucei, where it is the first example of a BAR-domain protein. To determine functional conservation, an initial characterisation of retromer was performed in T. brucei; the endosomal localisation and its role in endosomal targeting are conserved. Therefore retromer is identified as a further feature of the sophisticated intracellular trafficking machinery of the last eukaryotic common ancestor, with BAR domains representing a possible third independent mechanism of membrane-deformation arising in early eukaryotes.
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Affiliation(s)
- V Lila Koumandou
- Department of Pathology, University of Cambridge, Cambridge CB2 1QT, UK
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69
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del Pino I, Paarmann I, Karas M, Kilimann MW, Betz H. The trafficking proteins Vacuolar Protein Sorting 35 and Neurobeachin interact with the glycine receptor β-subunit. Biochem Biophys Res Commun 2011; 412:435-40. [PMID: 21821005 DOI: 10.1016/j.bbrc.2011.07.110] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022]
Abstract
Inhibitory glycine receptors (GlyRs) are densely packed in the postsynaptic membrane due to a high-affinity interaction of their β-subunits with the scaffolding protein gephyrin. Here, we used an affinity-based proteomic approach to identify the trafficking proteins Vacuolar Protein Sorting 35 (Vps35) and Neurobeachin (Nbea) as novel GlyR β-subunit (GlyRβ) interacting proteins in rat brain. Recombinant Vps35 and a central fragment of Nbea bound to the large intracellular loop of GlyRβ in glutathione-S-transferase pull-downs; in addition, Vps35 displayed binding to gephyrin. Immunocytochemical staining of spinal cord sections revealed Nbea immunoreactivity apposed to and colocalizing with marker proteins of inhibitory synapses. Our data are consistent with roles of Vps35 and Nbea in the retrieval and post-Golgi trafficking of synaptic GlyRs and possibly other neurotransmitter receptors.
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Affiliation(s)
- Isabel del Pino
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, D-60528 Frankfurt/Main, Germany
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70
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Finnigan GC, Hanson-Smith V, Houser BD, Park HJ, Stevens TH. The reconstructed ancestral subunit a functions as both V-ATPase isoforms Vph1p and Stv1p in Saccharomyces cerevisiae. Mol Biol Cell 2011; 22:3176-91. [PMID: 21737673 PMCID: PMC3164464 DOI: 10.1091/mbc.e11-03-0244] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The vacuolar ATPase complex in yeast contains two isoforms of subunit a that dictate the subcellular localization of the V-ATPase enzyme. The most recent common ancestor of subunit a (Anc.a) is reconstructed, and its function and localization in modern Saccharomyces cerevisiae are characterized. Anc.a is able to replace both subunit a isoforms. The vacuolar-type, proton-translocating ATPase (V-ATPase) is a multisubunit enzyme responsible for organelle acidification in eukaryotic cells. Many organisms have evolved V-ATPase subunit isoforms that allow for increased specialization of this critical enzyme. Differential targeting of the V-ATPase to specific subcellular organelles occurs in eukaryotes from humans to budding yeast. In Saccharomyces cerevisiae, the two subunit a isoforms are the only difference between the two V-ATPase populations. Incorporation of Vph1p or Stv1p into the V-ATPase dictates the localization of the V-ATPase to the vacuole or late Golgi/endosome, respectively. A duplication event within fungi gave rise to two subunit a genes. We used ancestral gene reconstruction to generate the most recent common ancestor of Vph1p and Stv1p (Anc.a) and tested its function in yeast. Anc.a localized to both the Golgi/endosomal network and vacuolar membrane and acidified these compartments as part of a hybrid V-ATPase complex. Trafficking of Anc.a did not require retrograde transport from the late endosome to the Golgi that has evolved for retrieval of the Stv1p isoform. Rather, Anc.a localized to both structures through slowed anterograde transport en route to the vacuole. Our results suggest an evolutionary model that describes the differential localization of the two yeast V-ATPase isoforms.
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Affiliation(s)
- Gregory C Finnigan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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71
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Abstract
The retromer complex coordinates retrograde transport of cargo proteins between endosomes and the trans-Golgi network. The sorting nexin SNX3 is required for the retrograde trafficking of Wntless, but not of other retrograde cargo proteins, revealing that the cargo specificity of retromer is provided by the sorting nexins.
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72
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Harterink M, Port F, Lorenowicz MJ, McGough IJ, Silhankova M, Betist MC, van Weering JRT, van Heesbeen RGHP, Middelkoop TC, Basler K, Cullen PJ, Korswagen HC. A SNX3-dependent retromer pathway mediates retrograde transport of the Wnt sorting receptor Wntless and is required for Wnt secretion. Nat Cell Biol 2011; 13:914-923. [PMID: 21725319 PMCID: PMC4052212 DOI: 10.1038/ncb2281] [Citation(s) in RCA: 255] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 05/17/2011] [Indexed: 02/08/2023]
Abstract
Wnt proteins are lipid-modified glycoproteins that play a central role in development, adult tissue homeostasis and disease. Secretion of Wnt proteins is mediated by the Wnt-binding protein Wntless (Wls), which transports Wnt from the Golgi network to the cell surface for release. It has recently been shown that recycling of Wls through a retromer-dependent endosome-to-Golgi trafficking pathway is required for efficient Wnt secretion, but the mechanism of this retrograde transport pathway is poorly understood. Here, we report that Wls recycling is mediated through a retromer pathway that is independent of the retromer sorting nexins SNX1-SNX2 and SNX5-SNX6. We have found that the unrelated sorting nexin, SNX3, has an evolutionarily conserved function in Wls recycling and Wnt secretion and show that SNX3 interacts directly with the cargo-selective subcomplex of the retromer to sort Wls into a morphologically distinct retrieval pathway. These results demonstrate that SNX3 is part of an alternative retromer pathway that functionally separates the retrograde transport of Wls from other retromer cargo.
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Affiliation(s)
- Martin Harterink
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Fillip Port
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Magdalena J. Lorenowicz
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Ian J. McGough
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Marie Silhankova
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Marco C. Betist
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Jan R. T. van Weering
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Roy G. H. P. van Heesbeen
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Teije C. Middelkoop
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Konrad Basler
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Peter J. Cullen
- Henry Wellcome Integrated Signaling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Hendrik C. Korswagen
- Hubrecht Institute, Royal Academy of Arts and Sciences and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
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73
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Abstract
Some proteins and lipids traffic from the plasma membrane to the trans Golgi network (TGN)/Golgi apparatus and the endoplasmic reticulum, via the retrograde transport route. Endosomes are an obligatory through station. Whether early, recycling and late endosomes all hand off material to the TGN have remained a matter of debate. In this review, we give a short historical overview on how retrograde transport was discovered and explored. We then summarize and critically discuss data that have been put forward in favour of the existence of trafficking interfaces between each of the different endocytic localizations and the TGN. We finally point out some conceptual and technological challenges that will have to be met to establish definite conclusions for each of these scenarios.
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Affiliation(s)
- Ludger Johannes
- Traffic, Signaling, and Delivery Laboratory, Centre de Recherche, Institut Curie, CNRS UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
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74
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Willnow TE, Carlo AS, Rohe M, Schmidt V. SORLA/SORL1, a neuronal sorting receptor implicated in Alzheimer's disease. Rev Neurosci 2010; 21:315-29. [PMID: 21086763 DOI: 10.1515/revneuro.2010.21.4.315] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The proteolytic breakdown of the amyloid precursor protein (APP) to neurotoxic amyloid-beta peptides in the brain has been recognized as a major pathological pathway in Alzheimer's disease (AD). Yet, the factors that control the processing of APP and their potential contribution to the common sporadic form of AD remain poorly understood. Here, we review recent findings from studies in patients and in animal models that led to the identification of a unique sorting receptor for APP in neurons, designated SORLA/SORL1, that emerges as a key player in amyloidogenic processing and as major genetic risk factor for AD.
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Affiliation(s)
- Thomas E Willnow
- Max-Delbrueck-Center for Molecular Medicine, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.
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75
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Gharakhanian E, Chima-Okereke O, Olson DK, Frost C, Kathleen Takahashi M. env1 Mutant of VPS35 gene exhibits unique protein localization and processing phenotype at Golgi and lysosomal vacuole in Saccharomyces cerevisiae. Mol Cell Biochem 2010; 346:187-95. [PMID: 20936498 DOI: 10.1007/s11010-010-0604-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 09/23/2010] [Indexed: 11/26/2022]
Abstract
The yeast vacuole is functionally and structurally equivalent to the mammalian lysosome. Delivery of resident and cargo proteins to the lysosome is vital for proper cellular operations, and failure to correctly target proteins to the organelle is correlated with the development of neurodegenerative and lysosomal storage diseases. We previously reported a novel mutant screen for vacuolar trafficking defects in yeast Saccharomyces cerevisiae that resulted in the isolation of env1, an allelic mutant of VPS35. As a member of the retromer complex, Vps35p binds directly to cargos and facilitates their retrograde transport to trans Golgi from endosomes. Our previous studies established that env1 exhibits unique pleiotropic phenotype in comparison to other tested VPS35 alleles including severe growth sensitivity to hygromycin B and internal accumulation of the precursor form of the vacuolar enzyme carboxypeptidase Y. Here, through a combination of sub-cellular fractionation and indirect immunofluorescence microscopy, we confirm and extend the unique phenotype of env1 to processing and localization of additional proteins within the vacuolar trafficking pathway. In comparative studies with a null and an allelic mutant of VPS35, env1 exhibited unique processing defects of retromer-independent vacuolar membrane enzyme alkaline phosphatase at the vacuole and significant Golgi localization of retromer cargos Vps10p and Kex2p despite compromised trafficking at the Golgi and late endosome interface.
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Affiliation(s)
- Editte Gharakhanian
- Department of Biological Sciences, California State University at Long Beach, 1250 Bellflower Blvd, Long Beach, CA 90840, USA.
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76
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Soper JH, Kehm V, Burd CG, Bankaitis VA, Lee VMY. Aggregation of α-synuclein in S. cerevisiae is associated with defects in endosomal trafficking and phospholipid biosynthesis. J Mol Neurosci 2010; 43:391-405. [PMID: 20890676 DOI: 10.1007/s12031-010-9455-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/17/2010] [Indexed: 01/08/2023]
Abstract
Parkinson's disease is the most common neurodegenerative movement disorder. α-Synuclein is a small synaptic protein that has been linked to familial Parkinson's disease (PD) and is also the primary component of Lewy bodies, the hallmark neuropathology found in the brain of sporadic and familial PD patients. The function of α-synuclein is currently unknown, although it has been implicated in the regulation of synaptic vesicle localization or fusion. Recently, overexpression of α-synuclein was shown to cause cytoplasmic vesicle accumulation in a yeast model of α-synuclein toxicity, but the exact role α-synuclein played in mediating this vesicle aggregation is unclear. Here, we show that α-synuclein induces aggregation of many yeast Rab GTPase proteins, that α-synuclein aggregation is enhanced in yeast mutants that produce high levels of acidic phospholipids, and that α-synuclein colocalizes with yeast membranes that are enriched for phosphatidic acid. Significantly, we demonstrate that α-synuclein expression induces vulnerability to perturbations of Ypt6 and other proteins involved in retrograde endosome-Golgi transport, linking a specific trafficking defect to α-synuclein phospholipid binding. These data suggest new pathogenic mechanisms for α-synuclein neurotoxicity.
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Affiliation(s)
- James H Soper
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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77
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Kim H, Kang H, Jang M, Chang JH, Miao Y, Jiang L, Hwang I. Homomeric interaction of AtVSR1 is essential for its function as a vacuolar sorting receptor. PLANT PHYSIOLOGY 2010; 154:134-48. [PMID: 20625000 PMCID: PMC2938145 DOI: 10.1104/pp.110.159814] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Vacuolar sorting receptors, BP80/VSRs, play a critical role in vacuolar trafficking of soluble proteins in plant cells. However, the mechanism of action of BP80 is not well understood. Here, we investigate the action mechanism of AtVSR1, a member of BP80 proteins in Arabidopsis (Arabidopsis thaliana), in vacuolar trafficking. AtVSR1 exists as multiple forms, including a high molecular mass homomeric complex in vivo. Both the transmembrane and carboxyl-terminal cytoplasmic domains of AtVSR1 are necessary for the homomeric interaction. The carboxyl-terminal cytoplasmic domain contains specific sequence information, whereas the transmembrane domain has a structural role in the homomeric interaction. In protoplasts, an AtVSR1 mutant, C2A, that contained alanine substitution of the region involved in the homomeric interaction, was defective in trafficking to the prevacuolar compartment and localized primarily to the trans-Golgi network. In addition, overexpression of C2A, but not wild-type AtVSR1, inhibited trafficking of soluble proteins to the vacuole and caused their secretion into the medium. Furthermore, C2A:hemagglutinin in transgenic plants interfered with the homomeric interaction of endogenous AtVSR1 and inhibited vacuolar trafficking of sporamin:green fluorescent protein. These data suggest that homomeric interaction of AtVSR1 is critical for its function as a vacuolar sorting receptor.
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78
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Tabuchi M, Yanatori I, Kawai Y, Kishi F. Retromer-mediated direct sorting is required for proper endosomal recycling of the mammalian iron transporter DMT1. J Cell Sci 2010; 123:756-66. [PMID: 20164305 DOI: 10.1242/jcs.060574] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Endosomal recycling of the mammalian iron transporter DMT1 is assumed to be important for efficient and rapid uptake of iron across the endosomal membrane in the transferrin cycle. Here, we show that the retromer, a complex that mediates retrograde transport of transmembrane cargoes from endosomes to the trans-Golgi network, is required for endosomal recycling of DMT1-II, an alternative splicing isoform of DMT1. Bacterially expressed Vps26-Vsp29-Vsp35 trimer, a retromer cargo recognition complex, specifically binds to the cytoplasmic tail domain of DMT1-II in vitro. In particular, this binding is dependent on a specific hydrophobic motif of DMT1-II, which is required for its endosomal recycling. DMT1-II colocalizes with the Vps35 subunit of the retromer in TfR-positive endosomes. Depletion of the retromer by siRNA against Vps35 leads to mis-sorting of DMT1-II to LAMP2-positive structures, and expression of siRNA-resistant Vps35 can rescue this effect. These findings demonstrate that the retromer recognizes the recycling signal of DMT1-II and ensures its proper endosomal recycling.
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Affiliation(s)
- Mitsuaki Tabuchi
- Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan.
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79
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Jovic M, Sharma M, Rahajeng J, Caplan S. The early endosome: a busy sorting station for proteins at the crossroads. Histol Histopathol 2010; 25:99-112. [PMID: 19924646 DOI: 10.14670/hh-25.99] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endocytosis marks the entry of internalized receptors into the complex network of endocytic trafficking pathways. Endocytic vesicles are rapidly targeted to a distinct membrane-bound endocytic organelle referred to as the early endosome. Despite the existence of numerous internalization routes, early endosomes (EE) serve as a focal point of the endocytic pathway. Sorting events initiated at this compartment determine the subsequent fate of internalized proteins and lipids, destining them either for recycling to the plasma membrane, degradation in lysosomes or delivery to the trans-Golgi network. Sorting of endocytic cargo to the latter compartments is accomplished through the formation of distinct microdomains within early endosomes, through the coordinate recruitment and assembly of the sorting machinery. An elaborate network of interactions between endocytic regulatory proteins ensures synchronized sorting of cargo to microdomains followed by morphological changes at the early endosomal membranes. Consequently, the cargo targeted either for recycling back to the plasma membrane, or for retrograde transport to the trans-Golgi network, localizes to newly-formed tubular membranes. With a high ratio of membrane surface to lumenal volume, these tubules effectively concentrate the recycling cargo, ensuring efficient transport out of the EE. Conversely, receptors sorted for degradation cluster at the flat clathrin lattices involved in invaginations of the limiting membrane, associating with newly formed intralumenal vesicles. In this review we will discuss the characteristics of early endosomes, their role in the regulation of endocytic transport, and their aberrant function in a variety of diseases.
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Affiliation(s)
- Marko Jovic
- Department of Biochemistry and Molecular Biology and Eppley Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5870, USA
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80
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Hashiguchi Y, Niihama M, Takahashi T, Saito C, Nakano A, Tasaka M, Morita MT. Loss-of-function mutations of retromer large subunit genes suppress the phenotype of an Arabidopsis zig mutant that lacks Qb-SNARE VTI11. THE PLANT CELL 2010; 22:159-72. [PMID: 20086190 PMCID: PMC2828691 DOI: 10.1105/tpc.109.069294] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Arabidopsis thaliana zigzag (zig) is a loss-of-function mutant of Qb-SNARE VTI11, which is involved in membrane trafficking between the trans-Golgi network and the vacuole. zig-1 exhibits abnormalities in shoot gravitropism and morphology. Here, we report that loss-of-function mutants of the retromer large subunit partially suppress the zig-1 phenotype. Moreover, we demonstrate that three paralogous VPS35 genes of Arabidopsis have partially overlapping but distinct genetic functions with respect to zig-1 suppression. Tissue-specific complementation experiments using an endodermis-specific SCR promoter show that expression of VPS35B or VPS35C cannot complement the function of VPS35A. The data suggest the existence of functionally specialized paralogous VPS35 genes that nevertheless share common functions.
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Affiliation(s)
- Yasuko Hashiguchi
- Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
| | - Mitsuru Niihama
- Plant Genetics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Tetsuya Takahashi
- Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
| | - Chieko Saito
- Molecular Membrane Biology Laboratory, RIKEN, Wako 351-0198, Japan
| | - Akihiko Nakano
- Molecular Membrane Biology Laboratory, RIKEN, Wako 351-0198, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masao Tasaka
- Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
| | - Miyo Terao Morita
- Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
- Address correspondence to
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81
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Affiliation(s)
- Naomi Attar
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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82
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Seaman MNJ, Harbour ME, Tattersall D, Read E, Bright N. Membrane recruitment of the cargo-selective retromer subcomplex is catalysed by the small GTPase Rab7 and inhibited by the Rab-GAP TBC1D5. J Cell Sci 2009; 122:2371-82. [PMID: 19531583 DOI: 10.1242/jcs.048686] [Citation(s) in RCA: 284] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Retromer is a membrane-associated heteropentameric coat complex that functions in the endosome-to-Golgi retrieval of the cation-independent mannose-6-phosphate receptor, the Wntless protein and other membrane proteins of physiological significance. Retromer comprises two functional subcomplexes: the cargo-selective subcomplex is a trimer of the VPS35, VPS29, VPS26 proteins, whereas the sorting nexin proteins, Snx1 and Snx2 function to tubulate the endosomal membrane. Unlike the sorting nexins, which contain PtdIns3P-binding PX domains, the cargo-selective VPS35/29/26 complex has no lipid-binding domains and its recruitment to the endosomal membrane remains mechanistically uncharacterised. In this study we show that the VPS35/29/26 complex interacts with the small GTPase Rab7 and requires Rab7 for its recruitment to the endosome. We show that the Rab7K157N mutant that causes the peripheral neuropathy, Charcot-Marie-Tooth disease, does not interact with the VPS35/29/26 complex, resulting in a weakened association with the membrane. We have also identified a novel retromer-interacting protein, TBC1D5, which is a member of the Rab GAP family of proteins that negatively regulates VPS35/29/26 recruitment and causes Rab7 to dissociate from the membrane. We therefore propose that recruitment of the cargo-selective VPS35/29/26 complex is catalysed by Rab7 and inhibited by the Rab-GAP protein, TBC1D5.
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Affiliation(s)
- Matthew N J Seaman
- University of Cambridge, Cambridge Institute for Medical Research, Department of Clinical Biochemistry, Wellcome Trust/MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK.
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83
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Rojas R, van Vlijmen T, Mardones GA, Prabhu Y, Rojas AL, Mohammed S, Heck AJR, Raposo G, van der Sluijs P, Bonifacino JS. Regulation of retromer recruitment to endosomes by sequential action of Rab5 and Rab7. ACTA ACUST UNITED AC 2008; 183:513-26. [PMID: 18981234 PMCID: PMC2575791 DOI: 10.1083/jcb.200804048] [Citation(s) in RCA: 402] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The retromer complex mediates retrograde transport of transmembrane cargo from endosomes to the trans-Golgi network (TGN). Mammalian retromer is composed of a sorting nexin (SNX) dimer that binds to phosphatidylinositol 3-phosphate–enriched endosomal membranes and a vacuolar protein sorting (Vps) 26/29/35 trimer that participates in cargo recognition. The mammalian SNX dimer is necessary but not sufficient for recruitment of the Vps26/29/35 trimer to membranes. In this study, we demonstrate that the guanosine triphosphatase Rab7 contributes to this recruitment. The Vps26/29/35 trimer specifically binds to Rab7–guanosine triphosphate (GTP) and localizes to Rab7-containing endosomal domains. Interference with Rab7 function causes dissociation of the Vps26/29/35 trimer but not the SNX dimer from membranes. This blocks retrieval of mannose 6-phosphate receptors to the TGN and impairs cathepsin D sorting. Rab5-GTP does not bind to the Vps26/29/35 trimer, but perturbation of Rab5 function causes dissociation of both the SNX and Vps26/29/35 components from membranes through inhibition of a pathway involving phosphatidylinositol 3-kinase. These findings demonstrate that Rab5 and Rab7 act in concert to regulate retromer recruitment to endosomes.
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Affiliation(s)
- Raul Rojas
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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84
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VPS10P-domain receptors — regulators of neuronal viability and function. Nat Rev Neurosci 2008; 9:899-909. [DOI: 10.1038/nrn2516] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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85
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Affiliation(s)
- Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
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86
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Kurischko C, Kuravi VK, Wannissorn N, Nazarov PA, Husain M, Zhang C, Shokat KM, McCaffery JM, Luca FC. The yeast LATS/Ndr kinase Cbk1 regulates growth via Golgi-dependent glycosylation and secretion. Mol Biol Cell 2008; 19:5559-78. [PMID: 18843045 DOI: 10.1091/mbc.e08-05-0455] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Saccharomyces cerevisiae Cbk1 is a LATS/Ndr protein kinase and a downstream component of the regulation of Ace2 and morphogenesis (RAM) signaling network. Cbk1 and the RAM network are required for cellular morphogenesis, cell separation, and maintenance of cell integrity. Here, we examine the phenotypes of conditional cbk1 mutants to determine the essential function of Cbk1. Cbk1 inhibition severely disrupts growth and protein secretion, and triggers the Swe1-dependent morphogenesis checkpoint. Cbk1 inhibition also delays the polarity establishment of the exocytosis regulators Rab-GTPase Sec4 and its exchange factor Sec2, but it does not interfere with actin polarity establishment. Cbk1 binds to and phosphorylates Sec2, suggesting that it regulates Sec4-dependent exocytosis. Intriguingly, Cbk1 inhibition causes a >30% decrease in post-Golgi vesicle accumulation in late secretion mutants, indicating that Cbk1 also functions upstream of Sec2-Sec4, perhaps at the level of the Golgi. In agreement, conditional cbk1 mutants mislocalize the cis-Golgi mannosyltransferase Och1, are hypersensitive to the aminoglycoside hygromycin B, and exhibit diminished invertase and Sim1 glycosylation. Significantly, the conditional lethality and hygromycin B sensitivity of cbk1 mutants are suppressed by moderate overexpression of several Golgi mannosyltransferases. These data suggest that an important function for Cbk1 and the RAM signaling network is to regulate growth and secretion via Golgi and Sec2/Sec4-dependent processes.
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Affiliation(s)
- Cornelia Kurischko
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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87
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Bassham DC, Brandizzi F, Otegui MS, Sanderfoot AA. The secretory system of Arabidopsis. THE ARABIDOPSIS BOOK 2008; 6:e0116. [PMID: 22303241 PMCID: PMC3243370 DOI: 10.1199/tab.0116] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Over the past few years, a vast amount of research has illuminated the workings of the secretory system of eukaryotic cells. The bulk of this work has been focused on the yeast Saccharomyces cerevisiae, or on mammalian cells. At a superficial level, plants are typical eukaryotes with respect to the operation of the secretory system; however, important differences emerge in the function and appearance of endomembrane organelles. In particular, the plant secretory system has specialized in several ways to support the synthesis of many components of the complex cell wall, and specialized kinds of vacuole have taken on a protein storage role-a role that is intended to support the growing seedling, but has been co-opted to support human life in the seeds of many crop plants. In the past, most research on the plant secretory system has been guided by results in mammalian or fungal systems but recently plants have begun to stand on their own as models for understanding complex trafficking events within the eukaryotic endomembrane system.
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Affiliation(s)
- Diane C. Bassham
- Department of Genetics, Development and Cell Biology and Plant Sciences Institute, Iowa State University, 455 Bessey Hall, Ames, Iowa 50011
| | - Federica Brandizzi
- MSU-DOE Plant Research Laboratory, Michigan State University, S-238 Plant Biology, East Lansing, Michigan 48824
| | - Marisa S. Otegui
- Department of Botany, University of Wisconsin- Madison, 224 Birge Hall, 430 Lincoln Drive, Madison, Wisconsin 53706
| | - Anton A. Sanderfoot
- Department of Plant Biology, University of Minnesota-Twin Cities, 250 Bioscience Center, 1445 Gortner Ave, St. Paul, Minnesota 55108
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88
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Retromer. Curr Opin Cell Biol 2008; 20:427-36. [PMID: 18472259 DOI: 10.1016/j.ceb.2008.03.009] [Citation(s) in RCA: 387] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 03/20/2008] [Accepted: 03/20/2008] [Indexed: 01/17/2023]
Abstract
The retromer is a heteropentameric complex that associates with the cytosolic face of endosomes and mediates retrograde transport of transmembrane cargo from endosomes to the trans-Golgi network. The mammalian retromer complex comprises a sorting nexin dimer composed of a still undefined combination of SNX1, SNX2, SNX5 and SNX6, and a cargo-recognition trimer composed of Vps26, Vps29 and Vps35. The SNX subunits contain PX and BAR domains that allow binding to PI(3)P enriched, highly curved membranes of endosomal vesicles and tubules, while Vps26, Vps29 and Vps35 have arrestin, phosphoesterase and alpha-solenoid folds, respectively. Recent studies have implicated retromer in a broad range of physiological, developmental and pathological processes, underscoring the critical nature of retrograde transport mediated by this complex.
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89
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Tarassov K, Messier V, Landry CR, Radinovic S, Serna Molina MM, Shames I, Malitskaya Y, Vogel J, Bussey H, Michnick SW. An in vivo map of the yeast protein interactome. Science 2008; 320:1465-70. [PMID: 18467557 DOI: 10.1126/science.1153878] [Citation(s) in RCA: 562] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein interactions regulate the systems-level behavior of cells; thus, deciphering the structure and dynamics of protein interaction networks in their cellular context is a central goal in biology. We have performed a genome-wide in vivo screen for protein-protein interactions in Saccharomyces cerevisiae by means of a protein-fragment complementation assay (PCA). We identified 2770 interactions among 1124 endogenously expressed proteins. Comparison with previous studies confirmed known interactions, but most were not known, revealing a previously unexplored subspace of the yeast protein interactome. The PCA detected structural and topological relationships between proteins, providing an 8-nanometer-resolution map of dynamically interacting complexes in vivo and extended networks that provide insights into fundamental cellular processes, including cell polarization and autophagy, pathways that are evolutionarily conserved and central to both development and human health.
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Affiliation(s)
- Kirill Tarassov
- Département de Biochimie, Université de Montréal Casier postal 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
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90
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Ruotolo R, Marchini G, Ottonello S. Membrane transporters and protein traffic networks differentially affecting metal tolerance: a genomic phenotyping study in yeast. Genome Biol 2008; 9:R67. [PMID: 18394190 PMCID: PMC2643938 DOI: 10.1186/gb-2008-9-4-r67] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2007] [Revised: 02/26/2008] [Accepted: 04/07/2008] [Indexed: 01/01/2023] Open
Abstract
Genomic phenotyping was used to assess the role of all non-essential S. cerevisiae proteins in modulating cell viability after exposure to cadmium, nickel and other metals. Background The cellular mechanisms that underlie metal toxicity and detoxification are rather variegated and incompletely understood. Genomic phenotyping was used to assess the roles played by all nonessential Saccharomyces cerevisiae proteins in modulating cell viability after exposure to cadmium, nickel, and other metals. Results A number of novel genes and pathways that affect multimetal as well as metal-specific tolerance were discovered. Although the vacuole emerged as a major hot spot for metal detoxification, we also identified a number of pathways that play a more general, less direct role in promoting cell survival under stress conditions (for example, mRNA decay, nucleocytoplasmic transport, and iron acquisition) as well as proteins that are more proximally related to metal damage prevention or repair. Most prominent among the latter are various nutrient transporters previously not associated with metal toxicity. A strikingly differential effect was observed for a large set of deletions, the majority of which centered on the ESCRT (endosomal sorting complexes required for transport) and retromer complexes, which - by affecting transporter downregulation and intracellular protein traffic - cause cadmium sensitivity but nickel resistance. Conclusion The data show that a previously underestimated variety of pathways are involved in cadmium and nickel tolerance in eukaryotic cells. As revealed by comparison with five additional metals, there is a good correlation between the chemical properties and the cellular toxicity signatures of various metals. However, many conserved pathways centered on membrane transporters and protein traffic affect cell viability with a surprisingly high degree of metal specificity.
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Affiliation(s)
- Roberta Ruotolo
- Department of Biochemistry and Molecular Biology, Viale G.P. Usberti 23/A, University of Parma, I-43100 Parma, Italy
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91
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Schluter C, Lam KK, Brumm J, Wu BW, Saunders M, Stevens TH, Bryan J, Conibear E. Global analysis of yeast endosomal transport identifies the vps55/68 sorting complex. Mol Biol Cell 2008; 19:1282-94. [PMID: 18216282 PMCID: PMC2291407 DOI: 10.1091/mbc.e07-07-0659] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 01/09/2008] [Accepted: 01/15/2008] [Indexed: 12/21/2022] Open
Abstract
Endosomal transport is critical for cellular processes ranging from receptor down-regulation and retroviral budding to the immune response. A full understanding of endosome sorting requires a comprehensive picture of the multiprotein complexes that orchestrate vesicle formation and fusion. Here, we use unsupervised, large-scale phenotypic analysis and a novel computational approach for the global identification of endosomal transport factors. This technique effectively identifies components of known and novel protein assemblies. We report the characterization of a previously undescribed endosome sorting complex that contains two well-conserved proteins with four predicted membrane-spanning domains. Vps55p and Vps68p form a complex that acts with or downstream of ESCRT function to regulate endosomal trafficking. Loss of Vps68p disrupts recycling to the TGN as well as onward trafficking to the vacuole without preventing the formation of lumenal vesicles within the MVB. Our results suggest the Vps55/68 complex mediates a novel, conserved step in the endosomal maturation process.
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Affiliation(s)
- Cayetana Schluter
- *Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Karen K.Y. Lam
- *Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Jochen Brumm
- Department of Statistics and Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z2, Canada; and
| | - Bella W. Wu
- *Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Matthew Saunders
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403-1229
| | - Tom H. Stevens
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403-1229
| | - Jennifer Bryan
- Department of Statistics and Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z2, Canada; and
| | - Elizabeth Conibear
- *Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
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92
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Abe M, Fujiwara M, Kurotani KI, Yokoi S, Shimamoto K. Identification of dynamin as an interactor of rice GIGANTEA by tandem affinity purification (TAP). PLANT & CELL PHYSIOLOGY 2008; 49:420-32. [PMID: 18296724 DOI: 10.1093/pcp/pcn019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
GIGANTEA (GI), CONSTANS (CO) and FLOWERING LOCUS T (FT) regulate photoperiodic flowering in Arabidopsis. In rice, OsGI, Hd1 and Hd3a were identified as orthologs of GI, CO and FT, respectively, and are also important regulators of flowering. Although GI has roles in both flowering and the circadian clock, our understanding of its biochemical functions is still limited. In this study, we purified novel OsGI-interacting proteins by using the tandem affinity purification (TAP) method. The TAP method has been used effectively in a number of model species to isolate proteins that interact with proteins of interest. However, in plants, the TAP method has been used in only a few studies, and no novel proteins have previously been isolated by this method. We generated transgenic rice plants and cell cultures expressing a TAP-tagged version of OsGI. After a two-step purification procedure, the interacting proteins were analyzed by mass spectrometry. Seven proteins, including dynamin, were identified as OsGI-interacting proteins. The interaction of OsGI with dynamin was verified by co-immunoprecipitation using a myc-tagged version of OsGI. Moreover, an analysis of Arabidopsis dynamin mutants indicated that although the flowering times of the mutants were not different from those of wild-type plants, an aerial rosette phenotype was observed in the mutants. We also found that OsGI is present in both the nucleus and the cytosol by Western blot analysis and by transient assays. These results indicate that the TAP method is effective for the isolation of novel proteins that interact with target proteins in plants.
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Affiliation(s)
- Makoto Abe
- Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan
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93
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Collins BM, Norwood SJ, Kerr MC, Mahony D, Seaman MNJ, Teasdale RD, Owen DJ. Structure of Vps26B and Mapping of its Interaction with the Retromer Protein Complex. Traffic 2008; 9:366-79. [PMID: 18088321 DOI: 10.1111/j.1600-0854.2007.00688.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
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94
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Vergés M. Retromer: multipurpose sorting and specialization in polarized transport. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 271:153-98. [PMID: 19081543 DOI: 10.1016/s1937-6448(08)01204-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Retromer is an evolutionary conserved protein complex required for endosome-to-Golgi retrieval of lysosomal hydrolases' receptors. A dimer of two sorting nexins-typically, SNX1 and/or SNX2-deforms the membrane and thus cooperates with retromer to ensure cargo sorting. Research in various model organisms indicates that retromer participates in sorting of additional molecules whose proper transport has important repercussions in development and disease. The role of retromer as well as SNXs in endosomal protein (re)cycling and protein targeting to specialized plasma membrane domains in polarized cells adds further complexity and has implications in growth control, the establishment of developmental patterns, cell adhesion, and migration. This chapter will discuss the functions of retromer described in various model systems and will focus on relevant aspects in polarized transport.
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Affiliation(s)
- Marcel Vergés
- Laboratory of Epithelial Cell Biology, Centro de Investigación Príncipe Felipe, C/E.P. Avda. Autopista del Saler, Valencia, Spain
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95
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Yang PT, Lorenowicz MJ, Silhankova M, Coudreuse DY, Betist MC, Korswagen HC. Wnt Signaling Requires Retromer-Dependent Recycling of MIG-14/Wntless in Wnt-Producing Cells. Dev Cell 2008; 14:140-7. [DOI: 10.1016/j.devcel.2007.12.004] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 11/15/2007] [Accepted: 12/07/2007] [Indexed: 10/22/2022]
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96
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Gokool S, Tattersall D, Reddy J, Seaman M. Identification of a conserved motif required for Vps35p/Vps26p interaction and assembly of the retromer complex. Biochem J 2007; 408:287-95. [PMID: 17696874 PMCID: PMC2267345 DOI: 10.1042/bj20070555] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The retromer complex is a conserved cytoplasmic coat complex that mediates the endosome-to-Golgi retrieval of vacuole/lysosome hydrolase receptors in yeast and mammals. The recognition of cargo proteins by the retromer is performed by the Vps35p/VPS35 (where Vps is vacuolar protein sorting) component, which together with Vps26p/VPS26 and Vps29p/VPS29, forms the cargo-selective subcomplex. In this report, we have identified a highly-conserved region of Vps35p/VPS35 that is essential for the interaction with Vps26p/VPS26 and for assembly of the retromer complex. Mutation of residues within the conserved region results in Vps35p/VPS35 mutants, which cannot bind to Vps26p/VPS26 and are not efficiently targeted to the endosomal membrane. These data implicate Vps26p/VPS26 in regulating Vps35p/VPS35 membrane association and therefore suggest a role for Vps26p/VPS26 in cargo recognition.
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Affiliation(s)
- Suzanne Gokool
- University of Cambridge, Cambridge Institute for Medical Research/Department of Clinical Biochemistry, Wellcome Trust/MRC building, Addenbrookes Hospital, Cambridge CB2 0XY, U.K
| | - Daniel Tattersall
- University of Cambridge, Cambridge Institute for Medical Research/Department of Clinical Biochemistry, Wellcome Trust/MRC building, Addenbrookes Hospital, Cambridge CB2 0XY, U.K
| | - Jonathan V. Reddy
- University of Cambridge, Cambridge Institute for Medical Research/Department of Clinical Biochemistry, Wellcome Trust/MRC building, Addenbrookes Hospital, Cambridge CB2 0XY, U.K
| | - Matthew N. J. Seaman
- University of Cambridge, Cambridge Institute for Medical Research/Department of Clinical Biochemistry, Wellcome Trust/MRC building, Addenbrookes Hospital, Cambridge CB2 0XY, U.K
- To whom all correspondence should be addressed (email )
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97
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Mari M, Bujny MV, Zeuschner D, Geerts WJC, Griffith J, Petersen CM, Cullen PJ, Klumperman J, Geuze HJ. SNX1 defines an early endosomal recycling exit for sortilin and mannose 6-phosphate receptors. Traffic 2007; 9:380-93. [PMID: 18088323 DOI: 10.1111/j.1600-0854.2007.00686.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mannose-6-phosphate receptors (MPRs) transport lysosomal hydrolases from the trans Golgi network (TGN) to endosomes. Recently, the multi-ligand receptor sortilin has also been implicated in this transport, but the transport carriers involved herein have not been identified. By quantitative immuno-electron microscopy, we localized endogenous sortilin of HepG2 cells predominantly to the TGN and endosomes. In the TGN, sortilin colocalized with MPRs in the same clathrin-coated vesicles. In endosomes, sortilin and MPRs concentrated in sorting nexin 1 (SNX1)-positive buds and vesicles. SNX1 depletion by small interfering RNA resulted in decreased pools of sortilin in the TGN and an increase in lysosomal degradation. These data indicate that sortilin and MPRs recycle to the TGN in SNX1-dependent carriers, which we named endosome-to-TGN transport carriers (ETCs). Notably, ETCs emerge from early endosomes (EE), lack recycling plasma membrane proteins and by three-dimensional electron tomography exhibit unique structural features. Hence, ETCs are distinct from hitherto described EE-derived membranes involved in recycling. Our data emphasize an important role of EEs in recycling to the TGN and indicate that different, specialized exit events occur on the same EE vacuole.
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Affiliation(s)
- Muriel Mari
- Cell Microscopy Center, Department of Cell Biology, Institute of Biomembranes, University Medical Centre (UMC) Utrecht, AZU Rm G02.525, 3584 CX Utrecht, The Netherlands
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98
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Seaman MNJ. Identification of a novel conserved sorting motif required for retromer-mediated endosome-to-TGN retrieval. J Cell Sci 2007; 120:2378-89. [PMID: 17606993 DOI: 10.1242/jcs.009654] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cation-independent mannose 6-phosphate receptor (CIMPR) cycles between the trans-Golgi network (TGN) and endosomes to mediate sorting of lysosomal hydrolases. The endosome-to-TGN retrieval of the CIMPR requires the retromer complex. Genetic, biochemical and structural data support the hypothesis that the retromer can directly bind to the tail of the CIMPR, to sort the CIMPR into vesicles and tubules for retrieval to the TGN. Presently, however, no known retromer sorting motif in the tail of the CIMPR has been identified. Using CD8-reporter proteins carrying the cytoplasmic tail of the CIMPR we have systematically dissected the CIMPR tail to identify a novel, conserved aromatic-containing sorting motif that is critical for the endosome-to-TGN retrieval of the CIMPR and for the interaction with retromer and the clathrin adaptor AP-1.
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Affiliation(s)
- Matthew N J Seaman
- University of Cambridge, Cambridge Institute for Medical Research/Clinical Biochemistry, Wellcome Trust/MRC building, Addenbrookes Hospital, Cambridge, CB2 0XY, UK.
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99
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Bujny MV, Popoff V, Johannes L, Cullen PJ. The retromer component sorting nexin-1 is required for efficient retrograde transport of Shiga toxin from early endosome to the trans Golgi network. J Cell Sci 2007; 120:2010-21. [PMID: 17550970 DOI: 10.1242/jcs.003111] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian retromer complex is a multi-protein complex that regulates retrograde transport of the cation-independent mannose 6-phosphate receptor (CI-MPR) from early endosomes to the trans Golgi network (TGN). It consists of two subcomplexes: a membrane-bound coat comprising sorting nexin-1 (SNX1) and possibly sorting nexin-2 (SNX2), and a cargo-selective subcomplex, composed of VPS26, VPS29 and VPS35. In addition to the retromer, a variety of other protein complexes has been suggested to regulate endosome-to-TGN transport of not only the CI-MPR but a wide range of other cargo proteins. Here, we have examined the role of SNX1 and SNX2 in endosomal sorting of Shiga and cholera toxins, two toxins that undergo endosome-to-TGN transport en route to their cellular targets located within the cytosol. By using small interfering RNA (siRNA)-mediated silencing combined with single-cell fluorescent-toxin-uptake assays and well-established biochemical assays to analyze toxin delivery to the TGN, we have established that suppression of SNX1 leads to a significant reduction in the efficiency of endosome-to-TGN transport of the Shiga toxin B-subunit. Furthermore, we show that for the B subunit of cholera toxin, retrograde endosome-to-TGN transport is less reliant upon SNX1. Overall, our data establish a role for SNX1 in the endosome-to-TGN transport of Shiga toxin and are indicative for a fundamental difference between endosomal sorting of Shiga and cholera toxins into endosome-to-TGN retrograde transport pathways.
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Affiliation(s)
- Miriam V Bujny
- The Henry Wellcome Integrated Signalling Laboratories, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, UK
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100
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Restrepo R, Zhao X, Peter H, Zhang BY, Arvan P, Nothwehr SF. Structural features of vps35p involved in interaction with other subunits of the retromer complex. Traffic 2007; 8:1841-1853. [PMID: 17892535 PMCID: PMC2504507 DOI: 10.1111/j.1600-0854.2007.00659.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The penta-subunit retromer complex of yeast mediates selective retrieval of membrane proteins from the prevacuolar endosome to the trans Golgi network. In this study, we set out to generate a panel of vps35 dominant-negative mutants that disrupt retromer-mediated cargo sorting. Mapping of the mutations revealed two types of alterations leading to dominant-negative behavior of the 944-amino acid protein: (i) mutations at or near the R(98) residue or (ii) C-terminal truncations exemplified by a nonsense mutation at codon 733. Both could be suppressed by overexpression of wild-type Vps35p, suggesting that these dominant-negative mutants compete for interactions with other retromer subunits. Interestingly, Vps35-R(98)W expression destabilized Vps26p while having no effect on Vps29p stability, while Vps35-Q(733)* expression affected Vps29p stability but had no effect on Vps26p. Measurement of Vps35/Vps26 and Vps35/Vps29 pairwise associations by coimmunoprecipitation in the presence or absence of other retromer subunits indicated that the R(98) residue, which is part of a conserved PRLYL motif, is critical for Vps35p binding to Vps26p, while both R(98) and residues 733-944 are needed for efficient binding to Vps29p.
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Affiliation(s)
- Ricardo Restrepo
- Division of Biological Sciences, 401 Tucker Hall, University of Missouri, Columbia, MO 65211, USA
| | - Xiang Zhao
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, 5560 MSRB2, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Harald Peter
- Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, D-70569 Stuttgart, Germany
| | - Bao-yan Zhang
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, 5560 MSRB2, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, 5560 MSRB2, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Steven F. Nothwehr
- Division of Biological Sciences, 401 Tucker Hall, University of Missouri, Columbia, MO 65211, USA
- *Corresponding author: Steven F. Nothwehr,
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