1
|
Greig J, Bates GT, Yin DI, Briant K, Simonetti B, Cullen PJ, Brodsky FM. CHC22 clathrin recruitment to the early secretory pathway requires two-site interaction with SNX5 and p115. EMBO J 2024:10.1038/s44318-024-00198-y. [PMID: 39160272 DOI: 10.1038/s44318-024-00198-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 07/15/2024] [Accepted: 07/17/2024] [Indexed: 08/21/2024] Open
Abstract
The two clathrin isoforms, CHC17 and CHC22, mediate separate intracellular transport routes. CHC17 performs endocytosis and housekeeping membrane traffic in all cells. CHC22, expressed most highly in skeletal muscle, shuttles the glucose transporter GLUT4 from the ERGIC (endoplasmic-reticulum-to-Golgi intermediate compartment) directly to an intracellular GLUT4 storage compartment (GSC), from where GLUT4 can be mobilized to the plasma membrane by insulin. Here, molecular determinants distinguishing CHC22 from CHC17 trafficking are defined. We show that the C-terminal trimerization domain of CHC22 interacts with SNX5, which also binds the ERGIC tether p115. SNX5, and the functionally redundant SNX6, are required for CHC22 localization independently of their participation in the endosomal ESCPE-1 complex. In tandem, an isoform-specific patch in the CHC22 N-terminal domain separately mediates binding to p115. This dual mode of clathrin recruitment, involving interactions at both N- and C-termini of the heavy chain, is required for CHC22 targeting to ERGIC membranes to mediate the Golgi-bypass route for GLUT4 trafficking. Interference with either interaction inhibits GLUT4 targeting to the GSC, defining a bipartite mechanism regulating a key pathway in human glucose metabolism.
Collapse
Affiliation(s)
- Joshua Greig
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - George T Bates
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Daowen I Yin
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Kit Briant
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK
| | - Boris Simonetti
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Peter J Cullen
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Frances M Brodsky
- Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London, WC1E 7HX, UK.
| |
Collapse
|
2
|
Yoshida S, Hasegawa T, Nakamura T, Sato K, Sugeno N, Ishiyama S, Sekiguchi K, Tobita M, Takeda A, Aoki M. Dysregulation of SNX1-retromer axis in pharmacogenetic models of Parkinson's disease. Cell Death Discov 2024; 10:290. [PMID: 38886344 PMCID: PMC11183211 DOI: 10.1038/s41420-024-02062-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/30/2024] [Accepted: 06/05/2024] [Indexed: 06/20/2024] Open
Abstract
Since the identification of vacuolar protein sorting (VPS) 35, as a causative molecule for familial Parkinson's disease (PD), retromer-mediated endosomal machinery has been a rising factor in the pathogenesis of the disease. The retromer complex cooperates with sorting nexin (SNX) dimer and DNAJC13, another causal molecule in PD, to transport cargoes from endosomes to the trans-Golgi network, and is also involved in mitochondrial dynamics and autophagy. Retromer dysfunction may induce neuronal death leading to PD via several biological cascades, including misfolded, insoluble α-synuclein (aS) accumulation and mitochondrial dysfunction; however, the detailed mechanisms remain poorly understood. In this study, we showed that the stagnation of retromer-mediated retrograde transport consistently occurs in different PD-mimetic conditions, i.e., overexpression of PD-linked mutant DNAJC13, excess aS induction, or toxin-induced mitochondrial dysfunction. Mechanistically, DNAJC13 was found to be involved in clathrin-dependent retromer transport as a functional modulator of SNX1 together with heat shock cognate 70 kDa protein (Hsc70), which was controlled by the binding and dissociation of DNAJC13 and SNX1 in an Hsc70 activity-dependent manner. In addition, excess amount of aS decreased the interaction between SNX1 and VPS35, the core component of retromer. Furthermore, R33, a pharmacological retromer chaperone, reduced insoluble aS and mitigated rotenone-induced neuronal apoptosis. These findings suggest that retrograde transport regulated by SNX1-retromer may be profoundly involved in the pathogenesis of PD and is a potential target for disease-modifying therapy for the disease.
Collapse
Grants
- 20K07896 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 23K06823 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 19K16998 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 23K14769 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 20K07862 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- 23K19557 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
Collapse
Affiliation(s)
- Shun Yoshida
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
- Department of Neurology, NHO Yonezawa National Hospital, Yonezawa, Yamagata, 992-1202, Japan
| | - Takafumi Hasegawa
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan.
- Department of Neurology, NHO Sendai-Nishitaga Hospital, Sendai, Miyagi, 982-8555, Japan.
| | - Takaaki Nakamura
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
- Department of Neurology, NHO Miyagi National Hospital, Watari, Miyagi, 989-2202, Japan
| | - Kazuki Sato
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
| | - Naoto Sugeno
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
| | - Shun Ishiyama
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
| | - Kiyotoshi Sekiguchi
- Division of Matrixome Research and Application, Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Muneshige Tobita
- Department of Neurology, NHO Yonezawa National Hospital, Yonezawa, Yamagata, 992-1202, Japan
| | - Atsushi Takeda
- Department of Neurology, NHO Sendai-Nishitaga Hospital, Sendai, Miyagi, 982-8555, Japan
| | - Masashi Aoki
- Division of Neurology, Department of Neuroscience & Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8574, Japan
| |
Collapse
|
3
|
Gopaldass N, Chen KE, Collins B, Mayer A. Assembly and fission of tubular carriers mediating protein sorting in endosomes. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00746-8. [PMID: 38886588 DOI: 10.1038/s41580-024-00746-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2024] [Indexed: 06/20/2024]
Abstract
Endosomes are central protein-sorting stations at the crossroads of numerous membrane trafficking pathways in all eukaryotes. They have a key role in protein homeostasis and cellular signalling and are involved in the pathogenesis of numerous diseases. Endosome-associated protein assemblies or coats collect transmembrane cargo proteins and concentrate them into retrieval domains. These domains can extend into tubular carriers, which then pinch off from the endosomal membrane and deliver the cargoes to appropriate subcellular compartments. Here we discuss novel insights into the structure of a number of tubular membrane coats that mediate the recruitment of cargoes into these carriers, focusing on sorting nexin-based coats such as Retromer, Commander and ESCPE-1. We summarize current and emerging views of how selective tubular endosomal carriers form and detach from endosomes by fission, highlighting structural aspects, conceptual challenges and open questions.
Collapse
Affiliation(s)
- Navin Gopaldass
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
| | - Kai-En Chen
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Brett Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
| |
Collapse
|
4
|
Tavares LA, Rodrigues RL, Santos da Costa C, Nascimento JA, Vargas de Carvalho J, Nogueira de Carvalho A, Mardones GA, daSilva LLP. AP-1γ2 is an adaptor protein 1 variant required for endosome-to-Golgi trafficking of the mannose-6-P receptor (CI-MPR) and ATP7B copper transporter. J Biol Chem 2024; 300:105700. [PMID: 38307383 PMCID: PMC10909764 DOI: 10.1016/j.jbc.2024.105700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 02/04/2024] Open
Abstract
Selective retrograde transport from endosomes back to the trans-Golgi network (TGN) is important for maintaining protein homeostasis, recycling receptors, and returning molecules that were transported to the wrong compartments. Two important transmembrane proteins directed to this pathway are the Cation-Independent Mannose-6-phosphate receptor (CI-MPR) and the ATP7B copper transporter. Among CI-MPR functions is the delivery of acid hydrolases to lysosomes, while ATP7B facilitates the transport of cytosolic copper ions into organelles or the extracellular space. Precise subcellular localization of CI-MPR and ATP7B is essential for the proper functioning of these proteins. This study shows that both CI-MPR and ATP7B interact with a variant of the clathrin adaptor 1 (AP-1) complex that contains a specific isoform of the γ-adaptin subunit called γ2. Through synchronized anterograde trafficking and cell-surface uptake assays, we demonstrated that AP-1γ2 is dispensable for ATP7B and CI-MPR exit from the TGN while being critically required for ATP7B and CI-MPR retrieval from endosomes to the TGN. Moreover, AP-1γ2 depletion leads to the retention of endocytosed CI-MPR in endosomes enriched in retromer complex subunits. These data underscore the importance of AP-1γ2 as a key component in the sorting and trafficking machinery of CI-MPR and ATP7B, highlighting its essential role in the transport of proteins from endosomes.
Collapse
Affiliation(s)
- Lucas Alves Tavares
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Roger Luiz Rodrigues
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Cristina Santos da Costa
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jonas Alburqueque Nascimento
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Julianne Vargas de Carvalho
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Andreia Nogueira de Carvalho
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Gonzalo A Mardones
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia, Chile
| | - Luis L P daSilva
- Center for Virology Research and Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
| |
Collapse
|
5
|
Lopez-Robles C, Scaramuzza S, Astorga-Simon EN, Ishida M, Williamson CD, Baños-Mateos S, Gil-Carton D, Romero-Durana M, Vidaurrazaga A, Fernandez-Recio J, Rojas AL, Bonifacino JS, Castaño-Díez D, Hierro A. Architecture of the ESCPE-1 membrane coat. Nat Struct Mol Biol 2023; 30:958-969. [PMID: 37322239 PMCID: PMC10352136 DOI: 10.1038/s41594-023-01014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 05/05/2023] [Indexed: 06/17/2023]
Abstract
Recycling of membrane proteins enables the reuse of receptors, ion channels and transporters. A key component of the recycling machinery is the endosomal sorting complex for promoting exit 1 (ESCPE-1), which rescues transmembrane proteins from the endolysosomal pathway for transport to the trans-Golgi network and the plasma membrane. This rescue entails the formation of recycling tubules through ESCPE-1 recruitment, cargo capture, coat assembly and membrane sculpting by mechanisms that remain largely unknown. Herein, we show that ESCPE-1 has a single-layer coat organization and suggest how synergistic interactions between ESCPE-1 protomers, phosphoinositides and cargo molecules result in a global arrangement of amphipathic helices to drive tubule formation. Our results thus define a key process of tubule-based endosomal sorting.
Collapse
Affiliation(s)
| | | | | | - Morié Ishida
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - David Gil-Carton
- CIC bioGUNE, Derio, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
- BREM Basque Resource for Electron Microscopy, Leioa, Spain
| | - Miguel Romero-Durana
- Barcelona Supercomputing Center (BSC), Barcelona, Spain
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC-Universidad de La Rioja-Gobierno de La Rioja, Logroño, Spain
| | | | - Juan Fernandez-Recio
- Barcelona Supercomputing Center (BSC), Barcelona, Spain
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC-Universidad de La Rioja-Gobierno de La Rioja, Logroño, Spain
| | | | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Daniel Castaño-Díez
- BioEM Lab, Biozentrum, University of Basel, Basel, Switzerland.
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain.
| | - Aitor Hierro
- CIC bioGUNE, Derio, Spain.
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
| |
Collapse
|
6
|
Carosi JM, Denton D, Kumar S, Sargeant TJ. Receptor Recycling by Retromer. Mol Cell Biol 2023; 43:317-334. [PMID: 37350516 PMCID: PMC10348044 DOI: 10.1080/10985549.2023.2222053] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 06/01/2023] [Indexed: 06/24/2023] Open
Abstract
The highly conserved retromer complex controls the fate of hundreds of receptors that pass through the endolysosomal system and is a central regulatory node for diverse metabolic programs. More than 20 years ago, retromer was discovered as an essential regulator of endosome-to-Golgi transport in yeast; since then, significant progress has been made to characterize how metazoan retromer components assemble to enable its engagement with endosomal membranes, where it sorts cargo receptors from endosomes to the trans-Golgi network or plasma membrane through recognition of sorting motifs in their cytoplasmic tails. In this review, we examine retromer regulation by exploring its assembled structure with an emphasis on how a range of adaptor proteins shape the process of receptor trafficking. Specifically, we focus on how retromer is recruited to endosomes, selects cargoes, and generates tubulovesicular carriers that deliver cargoes to target membranes. We also examine how cells adapt to distinct metabolic states by coordinating retromer expression and function. We contrast similarities and differences between retromer and its related complexes: retriever and commander/CCC, as well as their interplay in receptor trafficking. We elucidate how loss of retromer regulation is central to the pathology of various neurogenerative and metabolic diseases, as well as microbial infections, and highlight both opportunities and cautions for therapeutics that target retromer. Finally, with a focus on understanding the mechanisms that govern retromer regulation, we outline new directions for the field moving forward.
Collapse
Affiliation(s)
- Julian M. Carosi
- Lysosomal Health in Ageing, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- Centre for Cancer Biology, University of South Australia (UniSA), Adelaide, South Australia, Australia
- School of Biological Sciences, Faculty of Sciences, Engineering and Technology, The University of Adelaide, Adelaide, South Australia, Australia
| | - Donna Denton
- Centre for Cancer Biology, University of South Australia (UniSA), Adelaide, South Australia, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia (UniSA), Adelaide, South Australia, Australia
- Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Timothy J. Sargeant
- Lysosomal Health in Ageing, Lifelong Health, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| |
Collapse
|
7
|
Buser DP, Spang A. Protein sorting from endosomes to the TGN. Front Cell Dev Biol 2023; 11:1140605. [PMID: 36895788 PMCID: PMC9988951 DOI: 10.3389/fcell.2023.1140605] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/09/2023] [Indexed: 02/23/2023] Open
Abstract
Retrograde transport from endosomes to the trans-Golgi network is essential for recycling of protein and lipid cargoes to counterbalance anterograde membrane traffic. Protein cargo subjected to retrograde traffic include lysosomal acid-hydrolase receptors, SNARE proteins, processing enzymes, nutrient transporters, a variety of other transmembrane proteins, and some extracellular non-host proteins such as viral, plant, and bacterial toxins. Efficient delivery of these protein cargo molecules depends on sorting machineries selectively recognizing and concentrating them for their directed retrograde transport from endosomal compartments. In this review, we outline the different retrograde transport pathways governed by various sorting machineries involved in endosome-to-TGN transport. In addition, we discuss how this transport route can be analyzed experimentally.
Collapse
Affiliation(s)
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland
| |
Collapse
|
8
|
Dahhan DA, Reynolds GD, Cárdenas JJ, Eeckhout D, Johnson A, Yperman K, Kaufmann WA, Vang N, Yan X, Hwang I, Heese A, De Jaeger G, Friml J, Van Damme D, Pan J, Bednarek SY. Proteomic characterization of isolated Arabidopsis clathrin-coated vesicles reveals evolutionarily conserved and plant-specific components. THE PLANT CELL 2022; 34:2150-2173. [PMID: 35218346 PMCID: PMC9134090 DOI: 10.1093/plcell/koac071] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 02/22/2022] [Indexed: 05/26/2023]
Abstract
In eukaryotes, clathrin-coated vesicles (CCVs) facilitate the internalization of material from the cell surface as well as the movement of cargo in post-Golgi trafficking pathways. This diversity of functions is partially provided by multiple monomeric and multimeric clathrin adaptor complexes that provide compartment and cargo selectivity. The adaptor-protein assembly polypeptide-1 (AP-1) complex operates as part of the secretory pathway at the trans-Golgi network (TGN), while the AP-2 complex and the TPLATE complex jointly operate at the plasma membrane to execute clathrin-mediated endocytosis. Key to our further understanding of clathrin-mediated trafficking in plants will be the comprehensive identification and characterization of the network of evolutionarily conserved and plant-specific core and accessory machinery involved in the formation and targeting of CCVs. To facilitate these studies, we have analyzed the proteome of enriched TGN/early endosome-derived and endocytic CCVs isolated from dividing and expanding suspension-cultured Arabidopsis (Arabidopsis thaliana) cells. Tandem mass spectrometry analysis results were validated by differential chemical labeling experiments to identify proteins co-enriching with CCVs. Proteins enriched in CCVs included previously characterized CCV components and cargos such as the vacuolar sorting receptors in addition to conserved and plant-specific components whose function in clathrin-mediated trafficking has not been previously defined. Notably, in addition to AP-1 and AP-2, all subunits of the AP-4 complex, but not AP-3 or AP-5, were found to be in high abundance in the CCV proteome. The association of AP-4 with suspension-cultured Arabidopsis CCVs is further supported via additional biochemical data.
Collapse
Affiliation(s)
| | | | - Jessica J Cárdenas
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Dominique Eeckhout
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Alexander Johnson
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | | | - Walter A Kaufmann
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | - Nou Vang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Xu Yan
- College Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science & Technology, Pohang 37673, Korea
| | - Antje Heese
- Division of Biochemistry, Interdisciplinary Plant Group, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Geert De Jaeger
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Jiří Friml
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | - Daniël Van Damme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Jianwei Pan
- College Life Sciences, Lanzhou University, Lanzhou 730000, China
| | | |
Collapse
|
9
|
Dahhan DA, Reynolds GD, Cárdenas JJ, Eeckhout D, Johnson A, Yperman K, Kaufmann WA, Vang N, Yan X, Hwang I, Heese A, De Jaeger G, Friml J, Van Damme D, Pan J, Bednarek SY. Proteomic characterization of isolated Arabidopsis clathrin-coated vesicles reveals evolutionarily conserved and plant-specific components. THE PLANT CELL 2022; 34:2150-2173. [PMID: 35218346 DOI: 10.1101/2021.09.16.460678] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 02/22/2022] [Indexed: 05/26/2023]
Abstract
In eukaryotes, clathrin-coated vesicles (CCVs) facilitate the internalization of material from the cell surface as well as the movement of cargo in post-Golgi trafficking pathways. This diversity of functions is partially provided by multiple monomeric and multimeric clathrin adaptor complexes that provide compartment and cargo selectivity. The adaptor-protein assembly polypeptide-1 (AP-1) complex operates as part of the secretory pathway at the trans-Golgi network (TGN), while the AP-2 complex and the TPLATE complex jointly operate at the plasma membrane to execute clathrin-mediated endocytosis. Key to our further understanding of clathrin-mediated trafficking in plants will be the comprehensive identification and characterization of the network of evolutionarily conserved and plant-specific core and accessory machinery involved in the formation and targeting of CCVs. To facilitate these studies, we have analyzed the proteome of enriched TGN/early endosome-derived and endocytic CCVs isolated from dividing and expanding suspension-cultured Arabidopsis (Arabidopsis thaliana) cells. Tandem mass spectrometry analysis results were validated by differential chemical labeling experiments to identify proteins co-enriching with CCVs. Proteins enriched in CCVs included previously characterized CCV components and cargos such as the vacuolar sorting receptors in addition to conserved and plant-specific components whose function in clathrin-mediated trafficking has not been previously defined. Notably, in addition to AP-1 and AP-2, all subunits of the AP-4 complex, but not AP-3 or AP-5, were found to be in high abundance in the CCV proteome. The association of AP-4 with suspension-cultured Arabidopsis CCVs is further supported via additional biochemical data.
Collapse
Affiliation(s)
- Dana A Dahhan
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Gregory D Reynolds
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Jessica J Cárdenas
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Dominique Eeckhout
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Alexander Johnson
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | - Klaas Yperman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Walter A Kaufmann
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | - Nou Vang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Xu Yan
- College Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science & Technology, Pohang 37673, Korea
| | - Antje Heese
- Division of Biochemistry, Interdisciplinary Plant Group, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Geert De Jaeger
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Jiří Friml
- Institute of Science and Technology (IST Austria), Klosterneuburg 3400, Austria
| | - Daniël Van Damme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Jianwei Pan
- College Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Sebastian Y Bednarek
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
10
|
Yoshida S, Hasegawa T. Beware of Misdelivery: Multifaceted Role of Retromer Transport in Neurodegenerative Diseases. Front Aging Neurosci 2022; 14:897688. [PMID: 35601613 PMCID: PMC9120357 DOI: 10.3389/fnagi.2022.897688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Retromer is a highly integrated multimeric protein complex that mediates retrograde cargo sorting from endosomal compartments. In concert with its accessory proteins, the retromer drives packaged cargoes to tubular and vesicular structures, thereby transferring them to the trans-Golgi network or to the plasma membrane. In addition to the endosomal trafficking, the retromer machinery participates in mitochondrial dynamics and autophagic processes and thus contributes to cellular homeostasis. The retromer components and their associated molecules are expressed in different types of cells including neurons and glial cells, and accumulating evidence from genetic and biochemical studies suggests that retromer dysfunction is profoundly involved in the pathogenesis of neurodegenerative diseases including Alzheimer’s Disease and Parkinson’s disease. Moreover, targeting retromer components could alleviate the neurodegenerative process, suggesting that the retromer complex may serve as a promising therapeutic target. In this review, we will provide the latest insight into the regulatory mechanisms of retromer and discuss how its dysfunction influences the pathological process leading to neurodegeneration.
Collapse
Affiliation(s)
- Shun Yoshida
- Division of Neurology, Department of Neuroscience and Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Japan
- Department of Neurology, National Hospital Organization Yonezawa Hospital, Yonezawa, Japan
| | - Takafumi Hasegawa
- Division of Neurology, Department of Neuroscience and Sensory Organs, Tohoku University Graduate School of Medicine, Sendai, Japan
- *Correspondence: Takafumi Hasegawa,
| |
Collapse
|
11
|
Norris A, Grant BD. Endosomal microdomains: Formation and function. Curr Opin Cell Biol 2020; 65:86-95. [PMID: 32247230 PMCID: PMC7529669 DOI: 10.1016/j.ceb.2020.02.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 12/18/2022]
Abstract
It is widely recognized that after endocytosis, internalized cargo is delivered to endosomes that act as sorting stations. The limiting membrane of endosomes contain specialized subregions, or microdomains, that represent distinct functions of the endosome, including regions competing for cargo capture leading to degradation or recycling. Great progress has been made in defining the endosomal protein coats that sort cargo in these domains, including Retromer that recycles transmembrane cargo, and ESCRT (endosomal sorting complex required for transport) that degrades transmembrane cargo. In this review, we discuss recent work that is beginning to unravel how such coat complexes contribute to the creation and maintenance of endosomal microdomains. We highlight data that indicates that adjacent microdomains do not act independently but rather interact to cross-regulate. We posit that these interactions provide an agile means for the cell to adjust sorting in response to extracellular signals and intracellular metabolic cues.
Collapse
Affiliation(s)
- Anne Norris
- Rutgers University, Department of Molecular Biology and Biochemistry, Piscataway, NJ, 08854, USA
| | - Barth D Grant
- Rutgers University, Department of Molecular Biology and Biochemistry, Piscataway, NJ, 08854, USA.
| |
Collapse
|
12
|
Simonetti B, Cullen PJ. Actin-dependent endosomal receptor recycling. Curr Opin Cell Biol 2018; 56:22-33. [PMID: 30227382 DOI: 10.1016/j.ceb.2018.08.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/20/2018] [Accepted: 08/27/2018] [Indexed: 12/18/2022]
Abstract
Endosomes constitute major sorting compartments within the cell. There, a myriad of transmembrane proteins (cargoes) are delivered to the lysosome for degradation or retrieved from this fate and recycled through tubulo-vesicular transport carriers to different cellular destinations. Retrieval and recycling are orchestrated by multi-protein assemblies that include retromer and retriever, sorting nexins, and the Arp2/3 activating WASH complex. Fine-tuned control of actin polymerization on endosomes is fundamental for the retrieval and recycling of cargoes. Recent advances in the field have highlighted several roles that actin plays in this process including the binding to cargoes, stabilization of endosomal subdomains, generation of the remodeling forces required for the biogenesis of cargo-enriched transport carriers and short-range motility of the transport carriers.
Collapse
Affiliation(s)
- Boris Simonetti
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Peter J Cullen
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
| |
Collapse
|
13
|
Retrograde Transport by Clathrin-Coated Vesicles is Involved in Intracellular Transport of PrP Sc in Persistently Prion-Infected Cells. Sci Rep 2018; 8:12241. [PMID: 30115966 PMCID: PMC6095914 DOI: 10.1038/s41598-018-30775-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/03/2018] [Indexed: 12/22/2022] Open
Abstract
Intracellular dynamics of an abnormal isoform of prion protein (PrPSc) are tightly associated with prion propagation. However, the machineries involved in the intracellular trafficking of PrPSc are not fully understood. Our previous study suggested that PrPSc in persistently prion-infected cells dynamically circulates between endocytic-recycling compartments (ERCs) and peripheral regions of the cells. To investigate these machineries, we focused on retrograde transport from endosomes to the trans-Golgi network, which is one of the pathways involved in recycling of molecules. PrPSc was co-localized with components of clathrin-coated vesicles (CCVs) as well as those of the retromer complex, which are known as machineries for retrograde transport. Fractionation of intracellular compartments by density gradient centrifugation showed the presence of PrPSc and the components of CCVs in the same fractions. Furthermore, PrPSc was detected in CCVs isolated from intracellular compartments of prion-infected cells. Knockdown of clathrin interactor 1, which is one of the clathrin adaptor proteins involved in retrograde transport, did not change the amount of PrPSc, but it altered the distribution of PrPSc from ERCs to peripheral regions, including late endosomes/lysosomes. These data demonstrated that some PrPSc is transported from endosomes to ERCs by CCVs, which might be involved in the recycling of PrPSc.
Collapse
|
14
|
Abstract
The maintenance of cell surface proteins is critical to the ability of a cell to sense and respond to information in its environment. As such, modulation of cell surface composition and receptor trafficking is a potentially important target of control in virus infection. Sorting endosomes (SEs) are control stations regulating the recycling or degradation of internalized plasma membrane proteins. Here we report that human cytomegalovirus (HCMV), a ubiquitous betaherpesvirus, alters the fate of internalized clathrin-independent endocytosis (CIE) cargo proteins, retaining them in virally reprogrammed SEs. We show that the small G protein ARF6 (ADP ribosylation factor 6), a regulator of CIE trafficking, is highly associated with SE membranes relative to uninfected cells. Combined with the observation of accumulated CIE cargo at the SE, these results suggest that infection diminishes the egress of ARF6 and its cargo from the SE. Expression of ubiquitin-specific protease 6 (USP6), also known as TRE17, was sufficient to restore ARF6 and some ARF6 cargo trafficking to the cell surface in infected cells. The USP activity of TRE17 was required to rescue both ARF6 and associated cargo from SE retention in infection. The finding that TRE17 expression does not rescue the trafficking of all CIE cargos retained at SEs in infection suggests that HCMV hijacks the normal sorting machinery and selectively sorts specific cargos into endocytic microdomains that are subject to alternative sorting fates. Cells maintain their surface composition, take up nutrients, and respond to their environment through the internalization and recycling of cargo at the cell surface through endocytic trafficking pathways. During infection with human cytomegalovirus (HCMV), host endocytic membranes are reorganized into a juxtanuclear structure associated with viral assembly and egress. Less appreciated is the effect of this reorganization on the trafficking of host proteins through the endocytic pathway. We show that HCMV retains internalized cargo and the effector of clathrin-independent endocytosis at sorting endosomes. The retention of some cargo, but not all, was reversed by overexpression of a ubiquitin-specific protease, TRE17. Our results demonstrate that HCMV induces profound reprogramming of endocytic trafficking and influences cargo sorting decisions. Further, our work suggests the presence of a novel ubiquitin-regulated checkpoint for the recycling of cargo from sorting endosome. These findings have important implications for host signaling and immune pathways in the context of HCMV infection.
Collapse
|
15
|
Vieira N, Bessa C, Rodrigues AJ, Marques P, Chan FY, de Carvalho AX, Correia-Neves M, Sousa N. Sorting nexin 3 mutation impairs development and neuronal function in Caenorhabditis elegans. Cell Mol Life Sci 2018; 75:2027-2044. [PMID: 29196797 PMCID: PMC11105199 DOI: 10.1007/s00018-017-2719-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/27/2017] [Accepted: 11/22/2017] [Indexed: 02/07/2023]
Abstract
The sorting nexins family of proteins (SNXs) plays pleiotropic functions in protein trafficking and intracellular signaling and has been associated with several disorders, namely Alzheimer's disease and Down's syndrome. Despite the growing association of SNXs with neurodegeneration, not much is known about their function in the nervous system. The aim of this work was to use the nematode Caenorhabditis elegans that encodes in its genome eight SNXs orthologs, to dissect the role of distinct SNXs, particularly in the nervous system. By screening the C. elegans SNXs deletion mutants for morphological, developmental and behavioral alterations, we show here that snx-3 gene mutation leads to an array of developmental defects, such as delayed hatching, decreased brood size and life span and reduced body length. Additionally, ∆snx-3 worms present increased susceptibility to osmotic, thermo and oxidative stress and distinct behavioral deficits, namely, a chemotaxis defect which is independent of the described snx-3 role in Wnt secretion. ∆snx-3 animals also display abnormal GABAergic neuronal architecture and wiring and altered AIY interneuron structure. Pan-neuronal expression of C. elegans snx-3 cDNA in the ∆snx-3 mutant is able to rescue its locomotion defects, as well as its chemotaxis toward isoamyl alcohol. Altogether, the present work provides the first in vivo evidence of the SNX-3 role in the nervous system.
Collapse
Affiliation(s)
- Neide Vieira
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Carlos Bessa
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Ana J Rodrigues
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Paulo Marques
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Fung-Yi Chan
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular-IBMC, Porto, Portugal
| | - Ana Xavier de Carvalho
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular-IBMC, Porto, Portugal
| | - Margarida Correia-Neves
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.
- ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| |
Collapse
|
16
|
David DJ, Pagliuso A, Radoshevich L, Nahori MA, Cossart P. Lmo1656 is a secreted virulence factor of Listeria monocytogenes that interacts with the sorting nexin 6-BAR complex. J Biol Chem 2018; 293:9265-9276. [PMID: 29666193 PMCID: PMC6005434 DOI: 10.1074/jbc.ra117.000365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 04/09/2018] [Indexed: 12/14/2022] Open
Abstract
Listeria monocytogenes (Lm) is a facultative intracellular bacterial pathogen and the causative agent of listeriosis, a rare but fatal disease. During infection, Lm can traverse several physiological barriers; it can cross the intestine and placenta barrier and, in immunocompromised individuals, the blood–brain barrier. With the recent plethora of sequenced genomes available for Lm, it is clear that the complete repertoire of genes used by Lm to interact with its host remains to be fully explored. Recently, we focused on secreted Lm proteins because they are likely to interact with host cell components. Here, we investigated a putatively secreted protein of Lm, Lmo1656, that is present in most sequenced strains of Lm but absent in the nonpathogenic species Listeria innocua. lmo1656 gene is predicted to encode a small, positively charged protein. We show that Lmo1656 is secreted by Lm. Furthermore, deletion of the lmo1656 gene (Δlmo1656) attenuates virulence in mice infected orally but not intravenously, suggesting that Lmo1656 plays a role during oral listeriosis. We identified sorting nexin 6 (SNX6), an endosomal sorting component and BAR domain–containing protein, as a host cell interactor of Lmol656. SNX6 colocalizes with WT Lm during the early steps of infection. This colocalization depends on Lmo1656, and RNAi of SNX6 impairs infection in infected tissue culture cells, suggesting that SNX6 is utilized by Lm during infection. Our results reveal that Lmo1656 is a novel secreted virulence factor of Lm that facilitates recruitment of a specific member of the sorting nexin family in the mammalian host.
Collapse
Affiliation(s)
- Daryl Jason David
- From the Unité des Interactions Bactéries-Cellules, Department of Cell Biology and Infection, INSERM U604, Institut National de la Recherche Agronomique USC2020, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France
| | - Alessandro Pagliuso
- From the Unité des Interactions Bactéries-Cellules, Department of Cell Biology and Infection, INSERM U604, Institut National de la Recherche Agronomique USC2020, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France
| | - Lilliana Radoshevich
- From the Unité des Interactions Bactéries-Cellules, Department of Cell Biology and Infection, INSERM U604, Institut National de la Recherche Agronomique USC2020, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France
| | - Marie-Anne Nahori
- From the Unité des Interactions Bactéries-Cellules, Department of Cell Biology and Infection, INSERM U604, Institut National de la Recherche Agronomique USC2020, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France
| | - Pascale Cossart
- From the Unité des Interactions Bactéries-Cellules, Department of Cell Biology and Infection, INSERM U604, Institut National de la Recherche Agronomique USC2020, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France
| |
Collapse
|
17
|
Saimani U, Kim K. Traffic from the endosome towards trans-Golgi network. Eur J Cell Biol 2017; 96:198-205. [PMID: 28256269 DOI: 10.1016/j.ejcb.2017.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/24/2017] [Accepted: 02/16/2017] [Indexed: 11/16/2022] Open
Abstract
Retrograde passage of a transport carrier entails cargo sorting at the endosome, generation of a cargo-laden carrier and its movement along cytoskeletal tracks towards trans-Golgi network (TGN), tethering at the TGN, and fusion with the Golgi membrane. Significant advances have been made in understanding this traffic system, revealing molecular requirements in each step and the functional connection between them as well as biomedical implication of the dysregulation of those important traffic factors. This review focuses on describing up-to-date action mechanisms for retrograde transport from the endosomal system to the TGN.
Collapse
Affiliation(s)
- Uma Saimani
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States
| | - Kyoungtae Kim
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States.
| |
Collapse
|
18
|
SNX-1 and RME-8 oppose the assembly of HGRS-1/ESCRT-0 degradative microdomains on endosomes. Proc Natl Acad Sci U S A 2017; 114:E307-E316. [PMID: 28053230 DOI: 10.1073/pnas.1612730114] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
After endocytosis, transmembrane cargo reaches endosomes, where it encounters complexes dedicated to opposing functions: recycling and degradation. Microdomains containing endosomal sorting complexes required for transport (ESCRT)-0 component Hrs [hepatocyte growth factor-regulated tyrosine kinase substrate (HGRS-1) in Caenorhabditis elegans] mediate cargo degradation, concentrating ubiquitinated cargo and organizing the activities of ESCRT. At the same time, retromer associated sorting nexin one (SNX-1) and its binding partner, J-domain protein RME-8, sort cargo away from degradation, promoting cargo recycling to the Golgi. Thus, we hypothesized that there could be important regulatory interactions between retromer and ESCRT that balance degradative and recycling functions. Taking advantage of the naturally large endosomes of the C. elegans coelomocyte, we visualized complementary ESCRT-0 and RME-8/SNX-1 microdomains in vivo and assayed the ability of retromer and ESCRT microdomains to regulate one another. We found in snx-1(0) and rme-8(ts) mutants increased endosomal coverage and intensity of HGRS-1-labeled microdomains, as well as increased total levels of HGRS-1 bound to membranes. These effects are specific to SNX-1 and RME-8, as loss of other retromer components SNX-3 and vacuolar protein sorting-associated protein 35 (VPS-35) did not affect HGRS-1 microdomains. Additionally, knockdown of hgrs-1 had little to no effect on SNX-1 and RME-8 microdomains, suggesting directionality to the interaction. Separation of the functionally distinct ESCRT-0 and SNX-1/RME-8 microdomains was also compromised in the absence of RME-8 and SNX-1, a phenomenon we observed to be conserved, as depletion of Snx1 and Snx2 in HeLa cells also led to greater overlap of Rme-8 and Hrs on endosomes.
Collapse
|
19
|
Personnic N, Bärlocher K, Finsel I, Hilbi H. Subversion of Retrograde Trafficking by Translocated Pathogen Effectors. Trends Microbiol 2016; 24:450-462. [PMID: 26924068 DOI: 10.1016/j.tim.2016.02.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/22/2016] [Accepted: 02/01/2016] [Indexed: 12/22/2022]
Abstract
Intracellular bacterial pathogens subvert the endocytic bactericidal pathway to form specific replication-permissive compartments termed pathogen vacuoles or inclusions. To this end, the pathogens employ type III or type IV secretion systems, which translocate dozens, if not hundreds, of different effector proteins into their host cells, where they manipulate vesicle trafficking and signaling pathways in favor of the intruders. While the distinct cocktail of effectors defines the specific processes by which a pathogen vacuole is formed, the different pathogens commonly target certain vesicle trafficking routes, including the endocytic or secretory pathway. Recently, the retrograde transport pathway from endosomal compartments to the trans-Golgi network emerged as an important route affecting pathogen vacuole formation. Here, we review current insight into the host cell's retrograde trafficking pathway and how vacuolar pathogens of the genera Legionella, Coxiella, Salmonella, Chlamydia, and Simkania employ mechanistically distinct strategies to subvert this pathway, thus promoting intracellular survival and replication.
Collapse
Affiliation(s)
- Nicolas Personnic
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland
| | - Kevin Bärlocher
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland
| | - Ivo Finsel
- Max von Pettenkofer Institute, Ludwig-Maximilians University Munich, Pettenkoferstrasse 9a, 80336 Munich, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland; Max von Pettenkofer Institute, Ludwig-Maximilians University Munich, Pettenkoferstrasse 9a, 80336 Munich, Germany.
| |
Collapse
|
20
|
Abstract
The evolutionarily conserved endosomal retromer complex rescues transmembrane proteins from the lysosomal degradative pathway and facilitates their recycling to other cellular compartments. Retromer functions in conjunction with numerous associated proteins, including select members of the sorting nexin (SNX) family. In the present article, we review the molecular architecture and cellular roles of retromer and its various functional partners. The endosomal network is a crucial hub in the trafficking of proteins through the cellular endomembrane system. Transmembrane proteins, here termed cargos, enter endosomes by endocytosis from the plasma membrane or by trafficking from the trans-Golgi network (TGN). Endosomal cargo proteins face one of the two fates: retention in the endosome, leading ultimately to lysosomal degradation or export from the endosome for reuse ('recycling'). The balance of protein degradation and recycling is crucial to cellular homoeostasis; inappropriate sorting of proteins to either fate leads to cellular dysfunction. Retromer is an endosome-membrane-associated protein complex central to the recycling of many cargo proteins from endosomes, both to the TGN and the plasma membrane (and other specialized compartments, e.g. lysosome-related organelles). Retromer function is reliant on a number of proteins from the SNX family. In the present article, we discuss this inter-relationship and how defects in retromer function are increasingly being linked with human disease.
Collapse
|
21
|
Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
Collapse
Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
22
|
Klinger SC, Siupka P, Nielsen MS. Retromer-Mediated Trafficking of Transmembrane Receptors and Transporters. MEMBRANES 2015; 5:288-306. [PMID: 26154780 PMCID: PMC4584283 DOI: 10.3390/membranes5030288] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 06/29/2015] [Indexed: 12/21/2022]
Abstract
Transport between the endoplasmatic reticulum, the Golgi-network, the endo-lysosomal system and the cell surface can be categorized as anterograde or retrograde, describing traffic that goes forward or backward, respectively. Traffic going from the plasma membrane to endosomes and lysosomes or the trans-Golgi network (TGN) constitutes the major retrograde transport routes. Several transmembrane proteins undergo retrograde transport as part of a recycling mechanism that contributes to reutilization and maintenance of a steady-state protein localization. In addition, some receptors are hijacked by exotoxins and used for entry and intracellular transport. The physiological relevance of retrograde transport cannot be overstated. Retrograde trafficking of the amyloid precursor protein determines the distribution between organelles, and hence the possibility of cleavage by γ-secretase. Right balancing of the pathways is critical for protection against Alzheimer’s disease. During embryonic development, retrograde transport of Wntless to the TGN is essential for the following release of Wnt from the plasma membrane. Furthermore, overexpression of Wntless has been linked to oncogenesis. Here, we review relevant aspects of the retrograde trafficking of mammalian transmembrane receptors and transporters, with focus on the retromer-mediated transport between endosomes and the TGN.
Collapse
Affiliation(s)
- Stine C Klinger
- The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | - Piotr Siupka
- The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | - Morten S Nielsen
- The Lundbeck Foundation Initiative on Brain Barriers and Drug Delivery, Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| |
Collapse
|
23
|
Xhabija B, Vacratsis PO. Receptor-mediated Endocytosis 8 Utilizes an N-terminal Phosphoinositide-binding Motif to Regulate Endosomal Clathrin Dynamics. J Biol Chem 2015; 290:21676-89. [PMID: 26134565 DOI: 10.1074/jbc.m115.644757] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/06/2022] Open
Abstract
Receptor-mediated endocytosis 8 (RME-8) is a DnaJ domain containing protein implicated in translocation of Hsc70 to early endosomes for clathrin removal during retrograde transport. Previously, we have demonstrated that RME-8 associates with early endosomes in a phosphatidylinositol 3-phosphate (PI(3)P)-dependent fashion. In this study, we have now identified amino acid determinants required for PI(3)P binding within a region predicted to adopt a pleckstrin homology-like fold in the N terminus of RME-8. The ability of RME-8 to associate with PI(3)P and early endosomes is largely abolished when residues Lys(17), Trp(20), Tyr(24), or Arg(26) are mutated resulting in diffuse cytoplasmic localization of RME-8 while maintaining the ability to interact with Hsc70. We also provide evidence that RME-8 PI(3)P binding regulates early endosomal clathrin dynamics and alters the steady state localization of the cation-independent mannose 6-phosphate receptor. Interestingly, RME-8 endosomal association is also regulated by the PI(3)P-binding protein SNX1, a member of the retromer complex. Wild type SNX1 restores endosomal localization of RME-8 W20A, whereas a SNX1 variant deficient in PI(3)P binding disrupts endosomal localization of wild type RME-8. These results further highlight the critical role for PI(3)P in the RME-8-mediated organizational control of various endosomal activities, including retrograde transport.
Collapse
Affiliation(s)
- Besa Xhabija
- From the Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Panayiotis O Vacratsis
- From the Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| |
Collapse
|
24
|
Brodsky FM, Sosa RT, Ybe JA, O'Halloran TJ. Unconventional functions for clathrin, ESCRTs, and other endocytic regulators in the cytoskeleton, cell cycle, nucleus, and beyond: links to human disease. Cold Spring Harb Perspect Biol 2014; 6:a017004. [PMID: 25183831 DOI: 10.1101/cshperspect.a017004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The roles of clathrin, its regulators, and the ESCRT (endosomal sorting complex required for transport) proteins are well defined in endocytosis. These proteins can also participate in intracellular pathways that are independent of endocytosis and even independent of the membrane trafficking function of these proteins. These nonendocytic functions involve unconventional biochemical interactions for some endocytic regulators, but can also exploit known interactions for nonendocytic functions. The molecular basis for the involvement of endocytic regulators in unconventional functions that influence the cytoskeleton, cell cycle, signaling, and gene regulation are described here. Through these additional functions, endocytic regulators participate in pathways that affect infection, glucose metabolism, development, and cellular transformation, expanding their significance in human health and disease.
Collapse
Affiliation(s)
- Frances M Brodsky
- Department of Bioengineering and Therapeutic Sciences, Departments of Pharmaceutical Chemistry and Microbiology and Immunology, The G.W. Hooper Foundation, University of California, San Francisco, San Francisco, California 94143-0552
| | - R Thomas Sosa
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712-1095
| | - Joel A Ybe
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
| | - Theresa J O'Halloran
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712-1095
| |
Collapse
|
25
|
Shi Z, Baumgart T. Dynamics and instabilities of lipid bilayer membrane shapes. Adv Colloid Interface Sci 2014; 208:76-88. [PMID: 24529968 DOI: 10.1016/j.cis.2014.01.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/12/2014] [Accepted: 01/12/2014] [Indexed: 01/14/2023]
Abstract
Biological membranes undergo constant shape remodeling involving the formation of highly curved structures. The lipid bilayer represents the fundamental architecture of the cellular membrane with its shapes determined by the Helfrich curvature bending energy. However, the dynamics of bilayer shape transitions, especially their modulation by membrane proteins, and the resulting shape instabilities, are still not well understood. Here, we review in a unifying manner several theories that describe the fluctuations (i.e. undulations) of bilayer shapes as well as their local coupling with lipid or protein density variation. The coupling between local membrane curvature and lipid density gives rise to a 'slipping mode' in addition to the conventional 'bending mode' for damping the membrane fluctuation. This leads to a number of interesting experimental phenomena regarding bilayer shape dynamics. More importantly, curvature-inducing proteins can couple with membrane shape and eventually render the membrane unstable. A criterion for membrane shape instability is derived from a linear stability analysis. The instability criterion reemphasizes the importance of membrane tension in regulating the stability and dynamics of membrane geometry. Recent progresses in understanding the role of membrane tension in regulating dynamical cellular processes are also reviewed. Protein density is emphasized as a key factor in regulating membrane shape transitions: a threshold density of curvature coupling proteins is required for inducing membrane morphology transitions.
Collapse
Affiliation(s)
- Zheng Shi
- Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA 19104, USA
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, 231 S. 34th St., Philadelphia, PA 19104, USA.
| |
Collapse
|
26
|
Sierecki E, Stevers LM, Giles N, Polinkovsky ME, Moustaqil M, Mureev S, Johnston WA, Dahmer-Heath M, Skalamera D, Gonda TJ, Gabrielli B, Collins BM, Alexandrov K, Gambin Y. Rapid mapping of interactions between Human SNX-BAR proteins measured in vitro by AlphaScreen and single-molecule spectroscopy. Mol Cell Proteomics 2014; 13:2233-45. [PMID: 24866125 DOI: 10.1074/mcp.m113.037275] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein dimerization and oligomerization is commonly used by nature to increase the structural and functional complexity of proteins. Regulated protein assembly is essential to transfer information in signaling, transcriptional, and membrane trafficking events. Here we show that a combination of cell-free protein expression, a proximity based interaction assay (AlphaScreen), and single-molecule fluorescence allow rapid mapping of homo- and hetero-oligomerization of proteins. We have applied this approach to the family of BAR domain-containing sorting nexin (SNX-BAR) proteins, which are essential regulators of membrane trafficking and remodeling in all eukaryotes. Dimerization of BAR domains is essential for creating a concave structure capable of sensing and inducing membrane curvature. We have systematically mapped 144 pairwise interactions between the human SNX-BAR proteins and generated an interaction matrix of preferred dimerization partners for each family member. We find that while nine SNX-BAR proteins are able to form homo-dimers, several including the retromer-associated SNX1, SNX2, and SNX5 require heteromeric interactions for dimerization. SNX2, SNX4, SNX6, and SNX8 show a promiscuous ability to bind other SNX-BAR proteins and we also observe a novel interaction with the SNX3 protein which lacks the BAR domain structure.
Collapse
Affiliation(s)
- Emma Sierecki
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Loes M Stevers
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Nichole Giles
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Mark E Polinkovsky
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Mehdi Moustaqil
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Sergey Mureev
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Wayne A Johnston
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Mareike Dahmer-Heath
- §University of Queensland, Diamantina Institute, Translational Research Institute, Brisbane, Australia
| | - Dubravka Skalamera
- §University of Queensland, Diamantina Institute, Translational Research Institute, Brisbane, Australia
| | - Thomas J Gonda
- ¶School of Pharmacy, The University of Queensland, Brisbane, Australia
| | - Brian Gabrielli
- §University of Queensland, Diamantina Institute, Translational Research Institute, Brisbane, Australia
| | - Brett M Collins
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Kirill Alexandrov
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia;
| | - Yann Gambin
- From the ‡Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072 Australia
| |
Collapse
|
27
|
Abstract
The counterbalancing action of the endocytosis and secretory pathways maintains a dynamic equilibrium that regulates the composition of the plasma membrane, allowing it to maintain homeostasis and to change rapidly in response to alterations in the extracellular environment and/or intracellular metabolism. These pathways are intimately integrated with intercellular signaling systems and play critical roles in all cells. Studies in Caenorhabditis elegans have revealed diverse roles of membrane trafficking in physiology and development and have also provided molecular insight into the fundamental mechanisms that direct cargo sorting, vesicle budding, and membrane fisson and fusion. In this review, we summarize progress in understanding membrane trafficking mechanisms derived from work in C. elegans, focusing mainly on work done in non-neuronal cell-types, especially the germline, early embryo, coelomocytes, and intestine.
Collapse
Affiliation(s)
- Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan. ;
| | | | | | | |
Collapse
|
28
|
Lu L, Hong W. From endosomes to the trans-Golgi network. Semin Cell Dev Biol 2014; 31:30-9. [PMID: 24769370 DOI: 10.1016/j.semcdb.2014.04.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 04/16/2014] [Accepted: 04/16/2014] [Indexed: 12/11/2022]
Abstract
The retrograde trafficking from endosomes to the trans-Golgi network (TGN) is one of the major endocytic pathways to divert proteins and lipids away from lysosomal degradation. Retrograde transported cargos enter the TGN via two itineraries from either the early endosome/recycling endosome or the late endosome and involve various machinery components such as retromer, sorting nexins, clathrin, small GTPases, tethering factors and SNAREs. Recently, the pathway has been recognized for its role in signal transduction, physiology and pathogenesis of human diseases.
Collapse
Affiliation(s)
- Lei Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; School of Pharmaceutical Sciences, Xiamen University, Xiamen, People's Republic of China
| |
Collapse
|
29
|
Danson C, Brown E, Hemmings OJ, McGough IJ, Yarwood S, Heesom KJ, Carlton JG, Martin-Serrano J, May MT, Verkade P, Cullen PJ. SNX15 links clathrin endocytosis to the PtdIns3P early endosome independently of the APPL1 endosome. J Cell Sci 2013; 126:4885-99. [PMID: 23986476 DOI: 10.1242/jcs.125732] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sorting nexins (SNXs) are key regulators of the endosomal network. In designing an RNAi-mediated loss-of-function screen, we establish that of 30 human SNXs only SNX3, SNX5, SNX9, SNX15 and SNX21 appear to regulate EGF receptor degradative sorting. Suppression of SNX15 results in a delay in receptor degradation arising from a defect in movement of newly internalised EGF-receptor-labelled vesicles into early endosomes. Besides a phosphatidylinositol 3-phosphate- and PX-domain-dependent association to early endosomes, SNX15 also associates with clathrin-coated pits and clathrin-coated vesicles by direct binding to clathrin through a non-canonical clathrin-binding box. From live-cell imaging, it was identified that the activated EGF receptor enters distinct sub-populations of SNX15- and APPL1-labelled peripheral endocytic vesicles, which do not undergo heterotypic fusion. The SNX15-decorated receptor-containing sub-population does, however, undergo direct fusion with the Rab5-labelled early endosome. Our data are consistent with a model in which the EGF receptor enters the early endosome following clathrin-mediated endocytosis through at least two parallel pathways: maturation through an APPL1-intermediate compartment and an alternative more direct fusion between SNX15-decorated endocytic vesicles and the Rab5-positive early endosome.
Collapse
Affiliation(s)
- Chris Danson
- The Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Zlatic SA, Grossniklaus EJ, Ryder PV, Salazar G, Mattheyses AL, Peden AA, Faundez V. Chemical-genetic disruption of clathrin function spares adaptor complex 3-dependent endosome vesicle biogenesis. Mol Biol Cell 2013; 24:2378-88. [PMID: 23761069 PMCID: PMC3727930 DOI: 10.1091/mbc.e12-12-0860] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Clathrin–AP-3 association is dispensable for AP-3 vesicle budding from endosomes, which suggests that AP-3–clathrin interactions differ from those by which AP-1 and AP-2 adaptors productively engage clathrin in vesicle biogenesis. A role for clathrin in AP-3–dependent vesicle biogenesis has been inferred from biochemical interactions and colocalization between this adaptor and clathrin. The functionality of these molecular associations, however, is controversial. We comprehensively explore the role of clathrin in AP-3–dependent vesicle budding, using rapid chemical-genetic perturbation of clathrin function with a clathrin light chain–FKBP chimera oligomerizable by the drug AP20187. We find that AP-3 interacts and colocalizes with endogenous and recombinant FKBP chimeric clathrin polypeptides in PC12-cell endosomes. AP-3 displays, however, a divergent behavior from AP-1, AP-2, and clathrin chains. AP-3 cofractionates with clathrin-coated vesicle fractions isolated from PC12 cells even after clathrin function is acutely inhibited by AP20187. We predicted that AP20187 would inhibit AP-3 vesicle formation from endosomes after a brefeldin A block. AP-3 vesicle formation continued, however, after brefeldin A wash-out despite impairment of clathrin function by AP20187. These findings indicate that AP-3–clathrin association is dispensable for endosomal AP-3 vesicle budding and suggest that endosomal AP-3–clathrin interactions differ from those by which AP-1 and AP-2 adaptors productively engage clathrin in vesicle biogenesis.
Collapse
|