1
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Chen KE, Tillu VA, Gopaldass N, Chowdhury SR, Leneva N, Kovtun O, Ruan J, Guo Q, Ariotti N, Mayer A, Collins BM. Molecular basis for the assembly of the Vps5-Vps17 SNX-BAR proteins with Retromer. Nat Commun 2025; 16:3568. [PMID: 40234461 PMCID: PMC12000511 DOI: 10.1038/s41467-025-58846-8] [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: 04/05/2024] [Accepted: 04/02/2025] [Indexed: 04/17/2025] Open
Abstract
Retromer mediates endosomal retrieval of transmembrane proteins in all eukaryotes and was first discovered in yeast in complex with the Vps5 and Vps17 sorting nexins (SNXs). Cryoelectron tomography (cryoET) studies of Retromer-Vps5 revealed a pseudo-helical coat on membrane tubules where dimers of the Vps26 subunit bind Vps5 membrane-proximal domains. However, the Vps29 subunit is also required for Vps5-Vps17 association despite being far from the membrane. Here, we show that Vps5 binds both Vps29 and Vps35 subunits through its unstructured N-terminal domain. A Pro-Leu (PL) motif in Vps5 binds Vps29 and is required for association with Retromer on membrane tubules in vitro, and for the proper recycling of the Vps10 cargo in Saccharomyces cerevisiae. CryoET of Retromer tubules with Vps5-Vps17 heterodimers show a similar architecture to the coat with Vps5-Vps5 homodimers, however, the spatial relationship between Retromer units is highly restricted, likely due to more limited orientations for docking. These results provide mechanistic insights into how Retromer and SNX-BAR association has evolved across species.
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Affiliation(s)
- Kai-En Chen
- Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia
| | - Vikas A Tillu
- Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia
| | - Navin Gopaldass
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
| | | | - Natalya Leneva
- Research Group Molecular Mechanism of Membrane Trafficking, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Oleksiy Kovtun
- Research Group Molecular Mechanism of Membrane Trafficking, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Juanfang Ruan
- Electron Microscope Unit, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW, Australia
| | - Qian Guo
- Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia
| | - Nicholas Ariotti
- Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
| | - Brett M Collins
- Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia.
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2
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Wang D, Zhao X, Wang P, Liu JJ. SNX32 Regulates Sorting and Trafficking of Activated EGFR to the Lysosomal Degradation Pathway. Traffic 2024; 25:e12952. [PMID: 39073202 DOI: 10.1111/tra.12952] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 07/30/2024]
Abstract
SNX32 is a member of the evolutionarily conserved Phox (PX) homology domain- and Bin/Amphiphysin/Rvs (BAR) domain- containing sorting nexin (SNX-BAR) family of proteins, which play important roles in sorting and membrane trafficking of endosomal cargoes. Although SNX32 shares the highest amino acid sequence homology with SNX6, and has been believed to function redundantly with SNX5 and SNX6 in retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network (TGN), its role(s) in intracellular protein trafficking remains largely unexplored. Here, we report that it functions in parallel with SNX1 in mediating epidermal growth factor (EGF)-stimulated postendocytic trafficking of the epidermal growth factor receptor (EGFR). Moreover, SNX32 interacts directly with EGFR, and recruits SNX5 to promote sorting of EGF-EGFR into multivesicular bodies (MVBs) for lysosomal degradation. Thus, SNX32 functions distinctively from other SNX-BAR proteins to mediate signaling-coupled endolysosomal trafficking of EGFR.
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Affiliation(s)
- Dou Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xia Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Yunnan University, Kunming, China
| | - Panpan Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jia-Jia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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3
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Garcia Delgado L, Derome A, Longpré S, Giroux-Dansereau M, Basbous G, Lavoie C, Saucier C, Denault JB. Spatiotemporal regulation of the hepatocyte growth factor receptor MET activity by sorting nexins 1/2 in HCT116 colorectal cancer cells. Biosci Rep 2024; 44:BSR20240182. [PMID: 38836326 PMCID: PMC11196213 DOI: 10.1042/bsr20240182] [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: 02/07/2024] [Revised: 05/31/2024] [Accepted: 06/04/2024] [Indexed: 06/06/2024] Open
Abstract
Cumulative research findings support the idea that endocytic trafficking is crucial in regulating receptor signaling and associated diseases. Specifically, strong evidence points to the involvement of sorting nexins (SNXs), particularly SNX1 and SNX2, in the signaling and trafficking of the receptor tyrosine kinase (RTK) MET in colorectal cancer (CRC). Activation of hepatocyte growth factor (HGF) receptor MET is a key driver of CRC progression. In the present study, we utilized human HCT116 CRC cells with SNX1 and SNX2 genes knocked out to demonstrate that their absence leads to a delay in MET entering early endosomes. This delay results in increased phosphorylation of both MET and AKT upon HGF stimulation, while ERK1/2 (extracellular signal-regulated kinases 1 and 2) phosphorylation remains unaffected. Despite these changes, HGF-induced cell proliferation, scattering, and migration remain similar between the parental and the SNX1/2 knockout cells. However, in the absence of SNX1 and SNX2, these cells exhibit increased resistance to TRAIL-induced apoptosis. This research underscores the intricate relationship between intracellular trafficking, receptor signaling, and cellular responses and demonstrates for the first time that the modulation of MET trafficking by SNX1 and SNX2 is critical for receptor signaling that may exacerbate the disease.
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Affiliation(s)
- Laiyen Garcia Delgado
- Department of Pharmacology and Physiology
- Pharmacology Institute of Sherbrooke (IPS)
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
| | - Amélie Derome
- Department of Pharmacology and Physiology
- Pharmacology Institute of Sherbrooke (IPS)
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
| | - Samantha Longpré
- Department of Pharmacology and Physiology
- Pharmacology Institute of Sherbrooke (IPS)
| | | | - Ghenwa Basbous
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences
| | - Christine Lavoie
- Department of Pharmacology and Physiology
- Pharmacology Institute of Sherbrooke (IPS)
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Centre de Recherche Clinique CHUS
| | - Caroline Saucier
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences
- Centre de Recherche Clinique CHUS
| | - Jean-Bernard Denault
- Department of Pharmacology and Physiology
- Pharmacology Institute of Sherbrooke (IPS)
- Université de Sherbrooke’s Cancer Research Institute (IRCUS), Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences
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4
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Shortill SP, Frier MS, Davey M, Conibear E. N-terminal signals in the SNX-BAR paralogs Vps5 and Vin1 guide endosomal coat complex formation. Mol Biol Cell 2024; 35:ar76. [PMID: 38598303 PMCID: PMC11238075 DOI: 10.1091/mbc.e24-01-0043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 04/12/2024] Open
Abstract
Endosomal coats incorporate membrane-binding subunits such as sorting nexin (SNX) proteins. The Saccharomyces cerevisiae SNX-BAR paralogs Vin1 and Vps5 are respective subunits of the endosomal VINE and retromer complexes whose dimerizing BAR domains are required for complex assembly and membrane association. However, a degree of promiscuity is predicted for yeast BAR-BAR pairings, and recent work has implicated the unstructured N-terminal domains of Vin1 and Vps5 in coat formation. Here, we map N-terminal signals in both SNX-BAR paralogs that contribute to the assembly and function of two distinct endosomal coats in vivo. Whereas Vin1 leverages a polybasic region and adjacent hydrophobic motif to bind Vrl1 and form VINE, the N-terminus of Vps5 interacts with the retromer subunit Vps29 at two sites, including a conserved hydrophobic pocket in Vps29 that engages other accessory proteins in humans. We also examined the sole isoform of Vps5 from the milk yeast Kluyveromyces lactis and found that ancestral yeasts may have used a nested N-terminal signal to form both VINE and retromer. Our results suggest that the specific assembly of Vps5-family SNX-BAR coats depends on inputs from unique N-terminal sequence features in addition to BAR domain coupling, expanding our understanding of endosomal coat biology.
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Affiliation(s)
- Shawn P. Shortill
- Department of Medical Genetics, University of British Columbia, Vancouver, BC VH6 3N1, Canada
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Mia S. Frier
- Department of Medical Genetics, University of British Columbia, Vancouver, BC VH6 3N1, Canada
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Elizabeth Conibear
- Department of Medical Genetics, University of British Columbia, Vancouver, BC VH6 3N1, Canada
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
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5
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Overduin M, Bhat R. Recognition and remodeling of endosomal zones by sorting nexins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184305. [PMID: 38408696 DOI: 10.1016/j.bbamem.2024.184305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 02/05/2024] [Accepted: 02/18/2024] [Indexed: 02/28/2024]
Abstract
The proteolipid code determines how cytosolic proteins find and remodel membrane surfaces. Here, we investigate how this process works with sorting nexins Snx1 and Snx3. Both proteins form sorting machines by recognizing membrane zones enriched in phosphatidylinositol 3-phosphate (PI3P), phosphatidylserine (PS) and cholesterol. This co-localized combination forms a unique "lipid codon" or lipidon that we propose is responsible for endosomal targeting, as revealed by structures and interactions of their PX domain-based readers. We outline a membrane recognition and remodeling mechanism for Snx1 and Snx3 involving this code element alongside transmembrane pH gradients, dipole moment-guided docking and specific protein-protein interactions. This generates an initial membrane-protein assembly (memtein) that then recruits retromer and additional PX proteins to recruit cell surface receptors for sorting to the trans-Golgi network (TGN), lysosome and plasma membranes. Post-translational modification (PTM) networks appear to regulate how the sorting machines form and operate at each level. The commonalities and differences between these sorting nexins show how the proteolipid code orchestrates parallel flows of molecular information from ribosome emergence to organelle genesis, and illuminates a universally applicable model of the membrane.
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Affiliation(s)
- Michael Overduin
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
| | - Rakesh Bhat
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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6
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Codognoto VM, de Souza FF, Cataldi TR, Labate CA, de Camargo LS, Esteves Trindade PH, da Rosa Filho RR, de Oliveira DJB, Oba E. Proteomics approach reveals urinary markers for early pregnancy diagnosis in buffaloes. J Proteomics 2024; 290:105036. [PMID: 37879565 DOI: 10.1016/j.jprot.2023.105036] [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: 07/15/2023] [Revised: 09/21/2023] [Accepted: 10/12/2023] [Indexed: 10/27/2023]
Abstract
This study aimed to compare urine proteomics from non- and pregnant buffaloes in order to identify potential biomarkers of early pregnancy. Forty-four females underwent hormonal ovulation synchronization and were randomly divided into two experimental groups: inseminated (n = 30) and non-inseminated (n = 14). The pregnant females were further divided into two groups: pregnant at Day 12 (P12; n = 8) and at Day 18 (P18; n = 8) post-ovulation. The non-pregnant group was also subdivided into two groups: non-pregnant at Day 12 (NP12; n = 7) and at Day 18 (NP18; n = 7). Urine was collected from all females on Days 12 or 18. The samples were processed for proteomics. A total of 798 proteins were reported in the urine considering all groups. The differential proteins play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that some proteins from our study can be considered biomarkers for early pregnancy diagnosis, since they were increased in pregnant buffaloes. SIGNIFICANCE: Macromolecules have been studied for early pregnancy diagnosis, aiming to increase reproductive efficiency in cattle and buffaloes. Direct methods such as rectal palpation and ultrasonography have been considered late. Thus, this study aimed to compare urine proteomics from non- and pregnant buffaloes to identify potential biomarkers of early pregnancy. The differential proteins found in our study play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that these proteins can be considered possible biomarkers for early pregnancy diagnosis since they were increased in the pregnant buffaloes.
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Affiliation(s)
- Viviane M Codognoto
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Fabiana F de Souza
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Thais R Cataldi
- Department of Genetic, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Carlos A Labate
- Department of Genetic, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Laíza S de Camargo
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Pedro H Esteves Trindade
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Roberto R da Rosa Filho
- Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Campus São Paulo, São Paulo, Brazil
| | - Diego J B de Oliveira
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil
| | - Eunice Oba
- Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil.
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7
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Martija AA, Krauß A, Bächle N, Doth L, Christians A, Krunic D, Schneider M, Helm D, Will R, Hartmann C, Herold-Mende C, von Deimling A, Pusch S. EMP3 sustains oncogenic EGFR/CDK2 signaling by restricting receptor degradation in glioblastoma. Acta Neuropathol Commun 2023; 11:177. [PMID: 37936247 PMCID: PMC10629159 DOI: 10.1186/s40478-023-01673-z] [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: 04/18/2023] [Accepted: 10/19/2023] [Indexed: 11/09/2023] Open
Abstract
Epithelial membrane protein 3 (EMP3) is an N-glycosylated tetraspanin with a putative trafficking function. It is highly expressed in isocitrate dehydrogenase-wild-type glioblastoma (IDH-wt GBM), and its high expression correlates with poor survival. However, the exact trafficking role of EMP3 and how it promotes oncogenic signaling in GBM remain unclear. Here, we show that EMP3 promotes EGFR/CDK2 signaling by regulating the trafficking and enhancing the stability of EGFR. BioID2-based proximity labeling revealed that EMP3 interacts with endocytic proteins involved in the vesicular transport of EGFR. EMP3 knockout (KO) enhances epidermal growth factor (EGF)-induced shuttling of EGFR into RAB7 + late endosomes, thereby promoting EGFR degradation. Increased EGFR degradation is rescued by the RAB7 negative regulator and novel EMP3 interactor TBC1D5. Phosphoproteomic and transcriptomic analyses further showed that EMP3 KO converges into the inhibition of the cyclin-dependent kinase CDK2 and the repression of EGFR-dependent and cell cycle transcriptional programs. Phenotypically, EMP3 KO cells exhibit reduced proliferation rates, blunted mitogenic response to EGF, and increased sensitivity to the pan-kinase inhibitor staurosporine and the EGFR inhibitor osimertinib. Furthermore, EGFR-dependent patient-derived glioblastoma stem cells display a transcriptomic signature consistent with reduced CDK2 activity, as well as increased susceptibility to CDK2 inhibition upon EMP3 knockdown. Lastly, using TCGA data, we showed that GBM tumors with high EMP3 expression have increased total and phosphorylated EGFR levels. Collectively, our findings demonstrate a novel EMP3-dependent mechanism by which EGFR/CDK2 activity is sustained in GBM. Consequently, EMP3's stabilizing effect provides an additional layer of tumor cell resistance against targeted kinase inhibition.
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Affiliation(s)
- Antoni Andreu Martija
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Alexandra Krauß
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
- Faculty of Medicine, Heidelberg University, Heidelberg, Germany
| | - Natalie Bächle
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Laura Doth
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Arne Christians
- Department of Neuropathology, Institute of Pathology, Hannover Medical School, Hannover, Germany
- Canopy Biosciences, Bruker Nano Group, Hannover, Germany
| | - Damir Krunic
- Light Microscopy Facility, DKFZ, Heidelberg, Germany
| | | | - Dominic Helm
- Proteomics Core Facility, DKFZ, Heidelberg, Germany
| | - Rainer Will
- Cellular Tools Core Facility, DKFZ, Heidelberg, Germany
| | - Christian Hartmann
- Department of Neuropathology, Institute of Pathology, Hannover Medical School, Hannover, Germany
| | | | - Andreas von Deimling
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Stefan Pusch
- Clinical Cooperation Unit (CCU) Neuropathology, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany.
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8
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Balasubramaniam B, Topalidou I, Kelley M, Meadows SM, Funk O, Ailion M, Fay DS. Effectors of anterior morphogenesis in C. elegans embryos. Biol Open 2023; 12:bio059982. [PMID: 37345480 PMCID: PMC10339035 DOI: 10.1242/bio.059982] [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: 04/23/2023] [Accepted: 06/19/2023] [Indexed: 06/23/2023] Open
Abstract
During embryogenesis the nascent Caenorhabditis elegans epidermis secretes an apical extracellular matrix (aECM) that serves as an external stabilizer, preventing deformation of the epidermis by mechanical forces exerted during morphogenesis. At present, the factors that contribute to aECM function are mostly unknown, including the aECM components themselves, their posttranslational regulators, and the pathways required for their secretion. Here we showed that two proteins previously linked to aECM function, SYM-3/FAM102A and SYM-4/WDR44, colocalize to intracellular and membrane-associated puncta and likely function in a complex. Proteomics experiments also suggested potential roles for SYM-3/FAM102A and SYM-4/WDR44 family proteins in intracellular trafficking. Nonetheless, we found no evidence to support a critical function for SYM-3 or SYM-4 in the apical deposition of two aECM components, NOAH-1 and FBN-1. Moreover, loss of a key splicing regulator of fbn-1, MEC-8/RBPMS2, had surprisingly little effect on the abundance or deposition of FBN-1. Using a focused screening approach, we identified 32 additional proteins that likely contribute to the structure and function of the embryonic aECM. We also characterized morphogenesis defects in embryos lacking mir-51 microRNA family members, which display a similar phenotype to mec-8; sym double mutants. Collectively, these findings add to our knowledge of factors controlling embryonic morphogenesis.
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Affiliation(s)
- Boopathi Balasubramaniam
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie 82071-3944, WY, USA
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle 98195-7350, WA, USA
| | - Melissa Kelley
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie 82071-3944, WY, USA
| | - Sarina M. Meadows
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie 82071-3944, WY, USA
| | - Owen Funk
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie 82071-3944, WY, USA
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle 98195-7350, WA, USA
| | - David S. Fay
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie 82071-3944, WY, USA
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9
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Boopathi B, Topalidou I, Kelley M, Meadows SM, Funk O, Ailion M, Fay DS. Pathways that affect anterior morphogenesis in C. elegans embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.23.537986. [PMID: 37163004 PMCID: PMC10168279 DOI: 10.1101/2023.04.23.537986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
During embryogenesis the nascent Caenorhabditis elegans epidermis secretes an apical extracellular matrix (aECM) that serves as an external stabilizer, preventing deformation of the epidermis by mechanical forces exerted during morphogenesis. We showed that two conserved proteins linked to this process, SYM-3/FAM102A and SYM-4/WDR44, colocalize to intracellular and membrane-associated puncta and likely function together in a complex. Proteomics data also suggested potential roles for FAM102A and WDR44 family proteins in intracellular trafficking, consistent with their localization patterns. Nonetheless, we found no evidence to support a clear function for SYM-3 or SYM-4 in the apical deposition of two aECM components, FBN-1 and NOAH. Surprisingly, loss of MEC-8/RBPMS2, a conserved splicing factor and regulator of fbn-1 , had little effect on the abundance or deposition of FBN-1 to the aECM. Using a focused screening approach, we identified 32 additional proteins that likely contribute to the structure and function of the embryonic aECM. Lastly, we examined morphogenesis defects in embryos lacking mir-51 microRNA family members, which display a related embryonic phenotype to mec-8; sym double mutants. Collectively, our findings add to our knowledge of pathways controlling embryonic morphogenesis. SUMMARY STATEMENT We identify new proteins in apical ECM biology in C. elegans and provide evidence that SYM-3/FAM102A and SYM-4/WDR44 function together in trafficking but do not regulate apical ECM protein deposition.
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Affiliation(s)
- Balasubramaniam Boopathi
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming, United States of America
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, United States of America
| | - Melissa Kelley
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming, United States of America
| | - Sarina M Meadows
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming, United States of America
| | - Owen Funk
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming, United States of America
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, United States of America
| | - David S Fay
- Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming, United States of America
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10
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Huang J, Tiu AC, Jose PA, Yang J. Sorting nexins: role in the regulation of blood pressure. FEBS J 2023; 290:600-619. [PMID: 34847291 PMCID: PMC9149145 DOI: 10.1111/febs.16305] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 10/13/2021] [Accepted: 11/29/2021] [Indexed: 02/06/2023]
Abstract
Sorting nexins (SNXs) are a family of proteins that regulate cellular cargo sorting and trafficking, maintain intracellular protein homeostasis, and participate in intracellular signaling. SNXs are also important in the regulation of blood pressure via several mechanisms. Aberrant expression and dysfunction of SNXs participate in the dysregulation of blood pressure. Genetic studies show a correlation between SNX gene variants and the response to antihypertensive drugs. In this review, we summarize the progress in SNX-mediated regulation of blood pressure, discuss the potential role of SNXs in the pathophysiology and treatment of hypertension, and propose novel strategies for the medical therapy of hypertension.
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Affiliation(s)
- Juan Huang
- Department of Clinical Nutrition, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 410020, P.R. China
| | - Andrew C. Tiu
- Department of Medicine, Einstein Medical Center Philadelphia, Philadelphia, PA 19141, USA
| | - Pedro A. Jose
- Division of Renal Diseases & Hypertension, Department of Medicine, and Department of Physiology and Pharmacology, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
| | - Jian Yang
- Department of Clinical Nutrition, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 410020, P.R. China
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11
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Atwell B, Chen CY, Christofferson M, Montfort WR, Schroeder J. Sorting nexin-dependent therapeutic targeting of oncogenic epidermal growth factor receptor. Cancer Gene Ther 2023; 30:267-276. [PMID: 36253541 PMCID: PMC9935382 DOI: 10.1038/s41417-022-00541-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 09/15/2022] [Accepted: 09/27/2022] [Indexed: 11/09/2022]
Abstract
Overexpression and/or overactivation of the Epidermal Growth Factor Receptor (EGFR) is oncogenic in several tumor types yet targeting the kinase domain of wildtype EGFR has had limited success. EGFR has numerous kinase-independent roles, one of which is accomplished through the Sorting Nexin-dependent retrotranslocation of EGFR to the nucleus, which is observed in some metastatic cancers and therapeutically resistant disease. Here, we have utilized the BAR domain of Sorting Nexin 1 to create a peptide-based therapeutic (cSNX1.3) that promotes cell death in EGFR-expressing cancer. We evaluated the efficacy of cSNX1.3 in tumor-bearing WAP-TGFα transgenic mice (an EGFR-dependent model of breast cancer), where cSNX1.3 treatment resulted in significant tumor regression without observable toxicity. Evaluation of remaining tumor tissues found evidence of increased PARP cleavage, suggesting apoptotic tumor cell death. To evaluate the mechanism of action for cSNX1.3, we found that cSNX1.3 binds the C-terminus of the EGFR kinase domain at an interface site opposite the ATP binding domain with a Kd of ~4.0 µM. In vitro analysis found that cSNX1.3 inhibits the nuclear localization of EGFR. To determine specificity, we evaluated cancer cell lines expressing wildtype EGFR (MDA-MB-468, BT20 and A549), mutant EGFR (H1975) and non-transformed lines (CHO and MCF10A). Only transformed lines expressing wildtype EGFR responded to cSNX1.3, while mutant EGFR and normal cells responded better to an EGFR kinase inhibitor. Phenotypically, cSNX1.3 inhibits EGF-, NRG-, and HGF-dependent migration, but not HA-dependent migration. Together, these data indicate that targeting retrotranslocation of EGFR may be a potent therapeutic for RTK-active cancer.
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Affiliation(s)
- Benjamin Atwell
- Department of Molecular and Cellular Biology, 1007 E Lowell St, Tucson, AZ, 85721, USA
| | - Cheng-Yu Chen
- Department of Chemistry and Biochemistry, 1007 E Lowell St, Tucson, AZ, 85721, USA
| | | | - William R Montfort
- Department of Molecular and Cellular Biology, 1007 E Lowell St, Tucson, AZ, 85721, USA.,Department of Chemistry and Biochemistry, 1007 E Lowell St, Tucson, AZ, 85721, USA.,University of Arizona Cancer Center, 1007 E Lowell St, Tucson, AZ, 85721, USA.,BIO5 Institute, University of Arizona, 1007 E Lowell St, Tucson, AZ, 85721, USA
| | - Joyce Schroeder
- Department of Molecular and Cellular Biology, 1007 E Lowell St, Tucson, AZ, 85721, USA. .,University of Arizona Cancer Center, 1007 E Lowell St, Tucson, AZ, 85721, USA. .,BIO5 Institute, University of Arizona, 1007 E Lowell St, Tucson, AZ, 85721, USA.
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12
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Multifaceted Roles of Retromer in EGFR Trafficking and Signaling Activation. Cells 2022; 11:cells11213358. [DOI: 10.3390/cells11213358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/21/2022] [Accepted: 10/21/2022] [Indexed: 11/16/2022] Open
Abstract
Mammalian retromer complex contributes to multiple early endosome-associated trafficking pathways whose origins are dependent on which sorting nexin (SNX) they are complexed with. In an attempt to dissect out the contribution of individual retromer–SNX complexes, we examined the trafficking of EGFR in detail within a series of KO cell line models. We demonstrated that the depletion of retromer subunit Vps35 leads to decreased EGFR protein levels in resting cells with enhanced association of EGFR with lysosomal compartments. Compared to control cells, the addition of EGF to Vps35 KO cells resulted in a reduced rate of EGFR degradation; AKT activation and cell prolferation rates were elevated, while ERK activation remained relatively unchanged. These observations are consistent with a prolonged temporal association of EGFR within early endosomes due to the inefficiency of early endosome-associated protein trafficking pathways or organelle maturation due to retromer absence. We did not fully delineate the discrete contributions from retromer-associated SNXs to the phenotypes observed from retromer Vps35 depletion. While each of the knock-outs of SNX1/2, SNX3, or SNX27 promotes the enhanced association of EGFR with early endosomal compartments, only the decreased EGF-mediated EGFR degradation was observed in SNX1/2 dKO cells, while the enhanced AKT activation was only increased in SNX3 KO or SNX27 KO cells. Despite this, each of the knock-outs showed increased EGF-stimulated cell proliferation rates.
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13
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Shortill SP, Frier MS, Conibear E. You can go your own way: SNX-BAR coat complexes direct traffic at late endosomes. Curr Opin Cell Biol 2022; 76:102087. [DOI: 10.1016/j.ceb.2022.102087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/23/2022] [Accepted: 04/01/2022] [Indexed: 12/20/2022]
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14
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EGF-SNX3-EGFR axis drives tumor progression and metastasis in triple-negative breast cancers. Oncogene 2022; 41:220-232. [PMID: 34718348 PMCID: PMC8883427 DOI: 10.1038/s41388-021-02086-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 01/14/2023]
Abstract
Epidermal growth factor receptor (EGFR) has critical roles in epithelial cell physiology. Over-expression and over-activation of EGFR have been implicated in diverse cancers, including triple-negative breast cancers (TNBCs), prompting anti-EGFR therapies. Therefore, developing potent therapies and addressing the inevitable drug resistance mechanisms necessitates deciphering of EGFR related networks. Here, we describe Sorting Nexin 3 (SNX3), a member of the recycling retromer complex, as a critical player in the epidermal growth factor (EGF) stimulated EGFR network in TNBCs. We show that SNX3 is an immediate and sustained target of EGF stimulation initially at the protein level and later at the transcriptional level, causing increased SNX3 abundance. Using a proximity labeling approach, we observed increased interaction of SNX3 and EGFR upon EGF stimulation. We also detected colocalization of SNX3 with early endosomes and endocytosed EGF. Moreover, we show that EGFR protein levels are sensitive to SNX3 loss. Transient RNAi models of SNX3 downregulation have a temporary reduction in EGFR levels. In contrast, long-term silencing forces cells to recover and overexpress EGFR mRNA and protein, resulting in increased proliferation, colony formation, migration, invasion in TNBC cells, and increased tumor growth and metastasis in syngeneic models. Consistent with these results, low SNX3 and high EGFR mRNA levels correlate with poor relapse-free survival in breast cancer patients. Overall, our results suggest that SNX3 is a critical player in the EGFR network in TNBCs with implications for other cancers dependent on EGFR activity.
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15
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Podinovskaia M, Prescianotto-Baschong C, Buser DP, Spang A. A novel live-cell imaging assay reveals regulation of endosome maturation. eLife 2021; 10:e70982. [PMID: 34846303 PMCID: PMC8635980 DOI: 10.7554/elife.70982] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/09/2021] [Indexed: 12/12/2022] Open
Abstract
Cell-cell communication is an essential process in life, with endosomes acting as key organelles for regulating uptake and secretion of signaling molecules. Endocytosed material is accepted by the sorting endosome where it either is sorted for recycling or remains in the endosome as it matures to be degraded in the lysosome. Investigation of the endosome maturation process has been hampered by the small size and rapid movement of endosomes in most cellular systems. Here, we report an easy versatile live-cell imaging assay to monitor endosome maturation kinetics, which can be applied to a variety of mammalian cell types. Acute ionophore treatment led to enlarged early endosomal compartments that matured into late endosomes and fused with lysosomes to form endolysosomes. Rab5-to-Rab7 conversion and PI(3)P formation and turn over were recapitulated with this assay and could be observed with a standard widefield microscope. We used this approach to show that Snx1 and Rab11-positive recycling endosome recruitment occurred throughout endosome maturation and was uncoupled from Rab conversion. In contrast, efficient endosomal acidification was dependent on Rab conversion. The assay provides a powerful tool to further unravel various aspects of endosome maturation.
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Affiliation(s)
| | | | | | - Anne Spang
- Biozentrum, University of BaselBaselSwitzerland
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16
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Degrandmaison J, Grisé O, Parent JL, Gendron L. Differential barcoding of opioid receptors trafficking. J Neurosci Res 2021; 100:99-128. [PMID: 34559903 DOI: 10.1002/jnr.24949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 07/25/2021] [Accepted: 08/05/2021] [Indexed: 11/09/2022]
Abstract
Over the past several years, studies have highlighted the δ-opioid receptor (DOPr) as a promising therapeutic target for chronic pain management. While exhibiting milder undesired effects than most currently prescribed opioids, its specific agonists elicit effective analgesic responses in numerous animal models of chronic pain, including inflammatory, neuropathic, diabetic, and cancer-related pain. However, as compared with the extensively studied μ-opioid receptor, the molecular mechanisms governing its trafficking remain elusive. Recent advances have denoted several significant particularities in the regulation of DOPr intracellular routing, setting it apart from the other members of the opioid receptor family. Although they share high homology, each opioid receptor subtype displays specific amino acid patterns potentially involved in the regulation of its trafficking. These precise motifs or "barcodes" are selectively recognized by regulatory proteins and therefore dictate several aspects of the itinerary of a receptor, including its anterograde transport, internalization, recycling, and degradation. With a specific focus on the regulation of DOPr trafficking, this review will discuss previously reported, as well as potential novel trafficking barcodes within the opioid and nociceptin/orphanin FQ opioid peptide receptors, and their impact in determining distinct interactomes and physiological responses.
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Affiliation(s)
- Jade Degrandmaison
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Quebec Network of Junior Pain Investigators, QC, Canada
| | - Olivier Grisé
- Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Luc Parent
- Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Institut de Pharmacologie de Sherbrooke, Centre de Recherche du CHUS, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.,Quebec Pain Research Network, QC, Canada
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17
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Vieira N, Rito T, Correia-Neves M, Sousa N. Sorting Out Sorting Nexins Functions in the Nervous System in Health and Disease. Mol Neurobiol 2021; 58:4070-4106. [PMID: 33931804 PMCID: PMC8280035 DOI: 10.1007/s12035-021-02388-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/05/2021] [Indexed: 12/18/2022]
Abstract
Endocytosis is a fundamental process that controls protein/lipid composition of the plasma membrane, thereby shaping cellular metabolism, sensing, adhesion, signaling, and nutrient uptake. Endocytosis is essential for the cell to adapt to its surrounding environment, and a tight regulation of the endocytic mechanisms is required to maintain cell function and survival. This is particularly significant in the central nervous system (CNS), where composition of neuronal cell surface is crucial for synaptic functioning. In fact, distinct pathologies of the CNS are tightly linked to abnormal endolysosomal function, and several genome wide association analysis (GWAS) and biochemical studies have identified intracellular trafficking regulators as genetic risk factors for such pathologies. The sorting nexins (SNXs) are a family of proteins involved in protein trafficking regulation and signaling. SNXs dysregulation occurs in patients with Alzheimer’s disease (AD), Down’s syndrome (DS), schizophrenia, ataxia and epilepsy, among others, establishing clear roles for this protein family in pathology. Interestingly, restoration of SNXs levels has been shown to trigger synaptic plasticity recovery in a DS mouse model. This review encompasses an historical and evolutionary overview of SNXs protein family, focusing on its organization, phyla conservation, and evolution throughout the development of the nervous system during speciation. We will also survey SNXs molecular interactions and highlight how defects on SNXs underlie distinct pathologies of the CNS. Ultimately, we discuss possible strategies of intervention, surveying how our knowledge about the fundamental processes regulated by SNXs can be applied to the identification of novel therapeutic avenues for SNXs-related disorders.
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Affiliation(s)
- Neide Vieira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal. .,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Teresa Rito
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Margarida Correia-Neves
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, 4710-057, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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18
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Review of PIP2 in Cellular Signaling, Functions and Diseases. Int J Mol Sci 2020; 21:ijms21218342. [PMID: 33172190 PMCID: PMC7664428 DOI: 10.3390/ijms21218342] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
Phosphoinositides play a crucial role in regulating many cellular functions, such as actin dynamics, signaling, intracellular trafficking, membrane dynamics, and cell-matrix adhesion. Central to this process is phosphatidylinositol bisphosphate (PIP2). The levels of PIP2 in the membrane are rapidly altered by the activity of phosphoinositide-directed kinases and phosphatases, and it binds to dozens of different intracellular proteins. Despite the vast literature dedicated to understanding the regulation of PIP2 in cells over past 30 years, much remains to be learned about its cellular functions. In this review, we focus on past and recent exciting results on different molecular mechanisms that regulate cellular functions by binding of specific proteins to PIP2 or by stabilizing phosphoinositide pools in different cellular compartments. Moreover, this review summarizes recent findings that implicate dysregulation of PIP2 in many diseases.
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19
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Yang L, Tan W, Yang X, You Y, Wang J, Wen G, Zhong J. Sorting nexins: A novel promising therapy target for cancerous/neoplastic diseases. J Cell Physiol 2020; 236:3317-3335. [PMID: 33090492 DOI: 10.1002/jcp.30093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/17/2022]
Abstract
Sorting nexins (SNXs) are a diverse group of cytoplasmic- and membrane-associated phosphoinositide-binding proteins containing the PX domain proteins. The function of SNX proteins in regulating intracellular protein trafficking consists of endocytosis, endosomal sorting, and endosomal signaling. Dysfunctions of SNX proteins are demonstrated to be involved in several cancerous/neoplastic diseases. Here, we review the accumulated evidence of the molecular structure and biological function of SNX proteins and discuss the regulatory role of SNX proteins in distinct cancerous/neoplastic diseases. SNX family proteins may be a valuable potential biomarker and therapeutic strategy for diagnostics and treatment of cancerous/neoplastic diseases.
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Affiliation(s)
- Lu Yang
- Hunan Province Key Laboratory of Tumor Cellular & Molecular Pathology, Cancer Research Institute, University of South China, Hengyang, Hunan, China
- Institute of Clinical Medicine, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
| | - Weihua Tan
- Institute of Clinical Medicine, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
- Emergency Department, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
| | - Xinzhi Yang
- Hunan Province Key Laboratory of Tumor Cellular & Molecular Pathology, Cancer Research Institute, University of South China, Hengyang, Hunan, China
- Institute of Clinical Medicine, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
| | - Yong You
- Research Lab of Translational Medicine, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Jing Wang
- Research Lab of Translational Medicine, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Gebo Wen
- Hunan Province Key Laboratory of Tumor Cellular & Molecular Pathology, Cancer Research Institute, University of South China, Hengyang, Hunan, China
- Institute of Clinical Medicine, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
| | - Jing Zhong
- Hunan Province Key Laboratory of Tumor Cellular & Molecular Pathology, Cancer Research Institute, University of South China, Hengyang, Hunan, China
- Institute of Clinical Medicine, the First Affiliated Hospital of University of South China, Hengyang, Hunan, China
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20
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Host Retromer Protein Sorting Nexin 2 Interacts with Human Respiratory Syncytial Virus Structural Proteins and is Required for Efficient Viral Production. mBio 2020; 11:mBio.01869-20. [PMID: 32994321 PMCID: PMC7527724 DOI: 10.1128/mbio.01869-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The present study contributes new knowledge to understand HRSV assembly by providing evidence that nonglycosylated structural proteins M and N interact with elements of the secretory pathway, shedding light on their intracellular traffic. To the best of our knowledge, the present contribution is important given the scarcity of studies about the traffic of HRSV nonglycosylated proteins, especially by pointing to the involvement of SNX2, a retromer component, in the HRSV assembly process. Human respiratory syncytial virus (HRSV) envelope glycoproteins traffic to assembly sites through the secretory pathway, while nonglycosylated proteins M and N are present in HRSV inclusion bodies but must reach the plasma membrane, where HRSV assembly happens. Little is known about how nonglycosylated HRSV proteins reach assembly sites. Here, we show that HRSV M and N proteins partially colocalize with the Golgi marker giantin, and the glycosylated F and nonglycosylated N proteins are closely located in the trans-Golgi, suggesting their interaction in that compartment. Brefeldin A compromised the trafficking of HRSV F and N proteins and inclusion body sizes, indicating that the Golgi is important for both glycosylated and nonglycosylated HRSV protein traffic. HRSV N and M proteins colocalized and interacted with sorting nexin 2 (SNX2), a retromer component that shapes endosomes in tubular structures. Glycosylated F and nonglycosylated N HRSV proteins are detected in SNX2-laden aggregates with intracellular filaments projecting from their outer surfaces, and VPS26, another retromer component, was also found in inclusion bodies and filament-shaped structures. Similar to SNX2, TGN46 also colocalized with HRSV M and N proteins in filamentous structures at the plasma membrane. Cell fractionation showed enrichment of SNX2 in fractions containing HRSV M and N proteins. Silencing of SNX1 and 2 was associated with reduction in viral proteins, HRSV inclusion body size, syncytium formation, and progeny production. The results indicate that HRSV structural proteins M and N are in the secretory pathway, and SNX2 plays an important role in the traffic of HRSV structural proteins toward assembly sites.
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21
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Tom EC, Mushtaq I, Mohapatra BC, Luan H, Bhat AM, Zutshi N, Chakraborty S, Islam N, Arya P, Bielecki TA, Iseka FM, Bhattacharyya S, Cypher LR, Goetz BT, Negi SK, Storck MD, Rana S, Barnekow A, Singh PK, Ying G, Guda C, Natarajan A, Band V, Band H. EHD1 and RUSC2 Control Basal Epidermal Growth Factor Receptor Cell Surface Expression and Recycling. Mol Cell Biol 2020; 40:e00434-19. [PMID: 31932478 PMCID: PMC7076251 DOI: 10.1128/mcb.00434-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 09/26/2019] [Accepted: 12/26/2019] [Indexed: 01/25/2023] Open
Abstract
Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While postactivation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/preactivation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular structures and at the Golgi compartment. Inducible EHD1 knockdown reduced the cell surface EGFR expression with accumulation at the Golgi compartment, a phenotype rescued by exogenous EHD1. RUSC2 knockdown phenocopied the EHD1 depletion effects. EHD1 or RUSC2 depletion impaired the EGF-induced cell proliferation, demonstrating that the novel, EHD1- and RUSC2-dependent transport of unstimulated EGFR from the Golgi compartment to the cell surface that we describe is functionally important, with implications for physiologic and oncogenic roles of EGFR and targeted cancer therapies.
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Affiliation(s)
- Eric C Tom
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Insha Mushtaq
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Bhopal C Mohapatra
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Haitao Luan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Aaqib M Bhat
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Neha Zutshi
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Sukanya Chakraborty
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Namista Islam
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Priyanka Arya
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Timothy A Bielecki
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Fany M Iseka
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Sohinee Bhattacharyya
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Luke R Cypher
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Benjamin T Goetz
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Simarjeet K Negi
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Matthew D Storck
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Sandeep Rana
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Angelika Barnekow
- Department of Experimental Tumorbiology, Westfälische Wilhelms University Muenster, Muenster, Germany
| | - Pankaj K Singh
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Guoguang Ying
- Laboratory of Cancer Cell Biology, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Vimla Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Hamid Band
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
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22
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Chen Y, Leng M, Gao Y, Zhan D, Choi JM, Song L, Li K, Xia X, Zhang C, Liu M, Ji S, Jain A, Saltzman AB, Malovannaya A, Qin J, Jung SY, Wang Y. A Cross-Linking-Aided Immunoprecipitation/Mass Spectrometry Workflow Reveals Extensive Intracellular Trafficking in Time-Resolved, Signal-Dependent Epidermal Growth Factor Receptor Proteome. J Proteome Res 2019; 18:3715-3730. [PMID: 31442056 DOI: 10.1021/acs.jproteome.9b00427] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ligand binding to the cell surface receptors initiates signaling cascades that are commonly transduced through a protein-protein interaction (PPI) network to activate a plethora of response pathways. However, tools to capture the membrane PPI network are lacking. Here, we describe a cross-linking-aided mass spectrometry workflow for isolation and identification of signal-dependent epidermal growth factor receptor (EGFR) proteome. We performed protein cross-linking in cell culture at various time points following EGF treatment, followed by immunoprecipitation of endogenous EGFR and analysis of the associated proteins by quantitative mass spectrometry. We identified 140 proteins with high confidence during a 2 h time course by data-dependent acquisition and further validated the results by parallel reaction monitoring. A large proportion of proteins in the EGFR proteome function in endocytosis and intracellular protein transport. The EGFR proteome was highly dynamic with distinct temporal behavior; 10 proteins that appeared in all time points constitute the core proteome. Functional characterization showed that loss of the FYVE domain-containing proteins altered the EGFR intracellular distribution but had a minor effect on EGFR proteome or signaling. Thus, our results suggest that the EGFR proteome include functional regulators that influence EGFR signaling and bystanders that are captured as the components of endocytic vesicles. The high-resolution spatiotemporal information of these molecules facilitates the delineation of many pathways that could determine the strength and duration of the signaling, as well as the location and destination of the receptor.
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Affiliation(s)
- Yue Chen
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Mei Leng
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Yankun Gao
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Dongdong Zhan
- The Center for Bioinformatics and Computational Biology, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences , East China Normal University , Shanghai 200241 , China
| | - Jong Min Choi
- Advanced Technology Core, Baylor College of Medicine, Houston, Texas77030, United States
| | - Lei Song
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Kai Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Xia Xia
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Chunchao Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Mingwei Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Shuhui Ji
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China
| | - Antrix Jain
- Advanced Technology Core, Baylor College of Medicine, Houston, Texas77030, United States
| | - Alexander B Saltzman
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Anna Malovannaya
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States,Advanced Technology Core, Baylor College of Medicine, Houston, Texas77030, United States,Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas77030, United States,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Jun Qin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China.,The Center for Bioinformatics and Computational Biology, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences , East China Normal University , Shanghai 200241 , China.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Sung Yun Jung
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
| | - Yi Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center , National Center for Protein Sciences (The PHOENIX Center, Beijing), Institute of Lifeomics , Beijing 102206 , China.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77003, United States,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77003, United States
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Chen K, Healy MD, Collins BM. Towards a molecular understanding of endosomal trafficking by Retromer and Retriever. Traffic 2019; 20:465-478. [DOI: 10.1111/tra.12649] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Kai‐En Chen
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
| | - Michael D. Healy
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
| | - Brett M. Collins
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
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A Critical Role for Sorting Nexin 1 in the Trafficking of Metabotropic Glutamate Receptors. J Neurosci 2018; 38:8605-8620. [PMID: 30143569 DOI: 10.1523/jneurosci.0454-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/22/2018] [Accepted: 08/16/2018] [Indexed: 11/21/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluRs) function as modulators of neuronal physiology and they have also been implicated in various neuropsychiatric disorders. Trafficking of mGluRs plays important roles in controlling the precise localization of these receptors at specific region of the cell, as well as it regulates the activity of these receptors. Despite this obvious significance, we know very little about the cellular machineries that control the trafficking of these receptors in the CNS. Sorting nexin 1 (SNX1) has been shown to regulate the endosomal sorting of few cell surface receptors either to lysosomes where they are downregulated or back to the cell surface. Using "molecular replacement" approach in hippocampal neurons derived from mice of both sexes, we show here that SNX1 plays critical role in the trafficking of mGluR1, a member of the group I mGluR family. Overexpression of dominant-negative SNX1 or knockdown of endogenous SNX1 resulted in the rapid recycling of the receptor. Importantly, recycling via the rapid recycling route, did not allow the resensitization of the receptors. Our data suggest that both, N-terminal and C-terminal region of SNX1 play critical role in the normal trafficking of the receptor. In addition, we also show here that SNX1 regulates the trafficking of mGluR1 through the interaction with Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate), a protein that has been implicated in both signaling and vesicular trafficking. Thus, these studies reveal a mechanistic role of SNX1 in the trafficking of group I mGluRs and its physiological implications.SIGNIFICANCE STATEMENT Group I mGluRs are activated by the neurotransmitter glutamate in the CNS, and play various important roles in the brain. Similar to many other receptors, trafficking plays crucial roles in controlling the precise localization as well as activity of these receptors. Despite this obvious significance very little is known about the cellular machineries that control the trafficking of these receptors. We demonstrate here, that SNX1 plays a critical role in the trafficking of mGluR1, a member of the group I mGluR family. SNX1-mediated trafficking is critical for the resensitization of the receptor. SNX1 controls the trafficking of the receptor through the interaction with another protein, Hrs. The results suggest a role for SNX1 in the regulation of group I mGluRs.
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25
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Turashvili G, Lightbody ED, Tyryshkin K, SenGupta SK, Elliott BE, Madarnas Y, Ghaffari A, Day A, Nicol CJB. Novel prognostic and predictive microRNA targets for triple-negative breast cancer. FASEB J 2018; 32:fj201800120R. [PMID: 29812973 DOI: 10.1096/fj.201800120r] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Triple-negative breast cancers (TNBCs) account for ∼25% of all invasive carcinomas and represent a large subset of aggressive, high-grade tumors. Despite current research focused on understanding the genetic landscape of TNBCs, reliable prognostic and predictive biomarkers remain limited. Although dysregulated microRNAs (miRNAs) have emerged as key players in many cancer types, the role of miRNAs in TNBC disease progression is unclear. We performed miRNA profiling of 51 TNBCs by next-generation sequencing to reveal differentially expressed miRNAs. A total of 228 miRNAs were identified. Three miRNAs (miR-224-5p, miR-375, and miR-205-5p) separated the tumors based on basal status. Six miRNAs (high let-7d-3p, miR-203b-5p, and miR-324-5p; low miR-30a-3p, miR-30a-5p, and miR-199a-5p) were significantly associated with decreased overall survival (OS) and 5 miRNAs (high let-7d-3p; low miR-30a-3p, miR-30a-5p, miR-30c-5p, and miR-128-3p) with decreased relapse-free survival (RFS). On multivariate analysis, high expression of let-7d-3p and low expression of miR-30a were independent predictors of decreased OS and RFS. High expression of miR-95-3p was significantly associated with decreased OS and RFS in patients treated with anthracycline-based chemotherapy. Five miRNAs (let-7d-3p, miR-30a-3p, miR-30c-5p, miR-128-3p, and miR-95-3p) were validated by quantitative RT-PCR. Our findings unveil novel prognostic and predictive miRNA targets for TNBC, including a miRNA signature that predicts patient response to anthracycline-based chemotherapy. This may improve clinical management and/or lead to the development of novel therapies.-Turashvili, G., Lightbody, E. D., Tyryshkin, K., SenGupta, S. K., Elliott, B. E., Madarnas, Y., Ghaffari, A., Day, A., Nicol, C. J. B. Novel prognostic and predictive microRNA targets for triple-negative breast cancer.
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Affiliation(s)
- Gulisa Turashvili
- Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
- Department of Pathology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Elizabeth D Lightbody
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
| | - Kathrin Tyryshkin
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
| | - Sandip K SenGupta
- Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
| | - Bruce E Elliott
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
| | | | - Abdi Ghaffari
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
| | - Andrew Day
- Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Christopher J B Nicol
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Abubakar YS, Zheng W, Olsson S, Zhou J. Updated Insight into the Physiological and Pathological Roles of the Retromer Complex. Int J Mol Sci 2017; 18:ijms18081601. [PMID: 28757549 PMCID: PMC5577995 DOI: 10.3390/ijms18081601] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/13/2022] Open
Abstract
Retromer complexes mediate protein trafficking from the endosomes to the trans-Golgi network (TGN) or through direct recycling to the plasma membrane. In yeast, they consist of a conserved trimer of the cargo selective complex (CSC), Vps26-Vps35-Vps29 and a dimer of sorting nexins (SNXs), Vps5-Vps17. In mammals, the CSC interacts with different kinds of SNX proteins in addition to the mammalian homologues of Vps5 and Vps17, which further diversifies retromer functions. The retromer complex plays important roles in many cellular processes including restriction of invading pathogens. In this review, we summarize some recent developments in our understanding of the physiological and pathological functions of the retromer complex.
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Affiliation(s)
- Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Stefan Olsson
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Jie Zhou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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27
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Caspase-mediated proteolysis of the sorting nexin 2 disrupts retromer assembly and potentiates Met/hepatocyte growth factor receptor signaling. Cell Death Discov 2017; 3:16100. [PMID: 28179995 PMCID: PMC5253419 DOI: 10.1038/cddiscovery.2016.100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 11/23/2016] [Indexed: 12/14/2022] Open
Abstract
The unfolding of apoptosis involves the cleavage of hundreds of proteins by the caspase family of cysteinyl peptidases. Among those substrates are proteins involved in intracellular vesicle trafficking with a net outcome of shutting down the crucial processes governing protein transport to organelles and to the plasma membrane. However, because of the intertwining of receptor trafficking and signaling, cleavage of specific proteins may lead to unintended consequences. Here we show that in apoptosis, sorting nexin 1 and 2 (SNX1 and SNX2), two proteins involved in endosomal sorting, are cleaved by initiator caspases and also by executioner caspase-6 in the case of SNX2. Moreover, SNX1 is cleaved at multiple sites, including following glutamate residues. Cleavage of SNX2 results in a loss of association with the endosome-to-trans-Golgi network transport protein Vps35 and in a delocalization from endosomes of its associated partner Vps26. We also demonstrate that SNX2 depletion causes an increase in hepatocyte growth factor receptor tyrosine phosphorylation and Erk1/2 signaling in cells. Finally, we show that SNX2 mRNA and protein levels are decreased in colorectal carcinoma and that lower SNX2 gene expression correlates with an increase in cancer patient mortality. Our study reveals the importance to characterize the cleavage fragments produced by caspases of specific death substrates given their potential implication in the mechanism of regulation of physiological (signaling/trafficking) pathways or in the dysfunction leading to pathogenesis.
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28
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Tan X, Thapa N, Choi S, Anderson RA. Emerging roles of PtdIns(4,5)P2--beyond the plasma membrane. J Cell Sci 2015; 128:4047-56. [PMID: 26574506 PMCID: PMC4712784 DOI: 10.1242/jcs.175208] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Phosphoinositides are a collection of lipid messengers that regulate most subcellular processes. Amongst the seven phosphoinositide species, the roles for phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at the plasma membrane, such as in endocytosis, exocytosis, actin polymerization and focal adhesion assembly, have been extensively studied. Recent studies have argued for the existence of PtdIns(4,5)P2 at multiple intracellular compartments, including the nucleus, endosomes, lysosomes, autolysosomes, autophagic precursor membranes, ER, mitochondria and the Golgi complex. Although the generation, regulation and functions of PtdIns(4,5)P2 are less well-defined in most other intracellular compartments, accumulating evidence demonstrates crucial roles for PtdIns(4,5)P2 in endolysosomal trafficking, endosomal recycling, as well as autophagosomal pathways, which are the focus of this Commentary. We summarize and discuss how phosphatidylinositol phosphate kinases, PtdIns(4,5)P2 and PtdIns(4,5)P2-effectors regulate these intracellular protein and membrane trafficking events.
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Affiliation(s)
- Xiaojun Tan
- Program in Molecular and Cellular Pharmacology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Narendra Thapa
- Program in Molecular and Cellular Pharmacology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Suyong Choi
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- Program in Molecular and Cellular Pharmacology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA Program in Cellular and Molecular Biology, University of Wisconsin-Madison School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
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Abstract
The lysosomal degradation of G protein-coupled receptors (GPCRs) is essential for receptor signaling and down regulation. Once internalized, GPCRs are sorted within the endocytic pathway and packaged into intraluminal vesicles (ILVs) that bud inward to form the multivesicular endosome (MVE). The mechanisms that control GPCR sorting and ILV formation are poorly understood. Quantitative strategies are important for evaluating the function of adaptor and scaffold proteins that regulate sorting of GPCRs at MVEs. In this chapter, we outline two strategies for the quantification and visualization of GPCR sorting into the lumen of MVEs. The first protocol utilizes a biochemical approach to assay the sorting of GPCRs in a population of cells, whereas the second strategy examines GPCR sorting in individual cells using immunofluorescence confocal microscopy. Combined, these assays can be used to establish the kinetics of activated GPCR lysosomal trafficking in response to specific ligands, as well as evaluate the contribution of endosomal adaptors to GPCR sorting at MVEs. The protocols presented in this chapter can be adapted to analyze GPCR sorting in a myriad of cell types and tissues, and expanded to analyze the mechanisms that regulate MVE sorting of other cargoes.
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Affiliation(s)
- Michael Robert Dores
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - JoAnn Trejo
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA, USA
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Brennand A, Rico E, Rigden DJ, Van Der Smissen P, Courtoy PJ, Michels PAM. ATG24 Represses Autophagy and Differentiation and Is Essential for Homeostasy of the Flagellar Pocket in Trypanosoma brucei. PLoS One 2015; 10:e0130365. [PMID: 26090847 PMCID: PMC4474607 DOI: 10.1371/journal.pone.0130365] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/18/2015] [Indexed: 12/30/2022] Open
Abstract
We have previously identified homologs for nearly half of the approximately 30 known yeast Atg’s in the genome database of the human sleeping sickness parasite Trypanosoma brucei. So far, only a few of these homologs have their role in autophagy experimentally confirmed. Among the candidates was the ortholog of Atg24 that is involved in pexophagy in yeast. In T. brucei, the peroxisome-like organelles named glycosomes harbor core metabolic processes, especially glycolysis. In the autotrophic yeast, autophagy is essential for adaptation to different nutritional environments by participating in the renewal of the peroxisome population. We hypothesized that autophagic turnover of the parasite’s glycosomes plays a role in differentiation during its life cycle, which demands adaptation to different host environments and associated dramatic changes in nutritional conditions. We therefore characterized T. brucei ATG24, the T. brucei ortholog of yeast Atg24 and mammalian SNX4, and found it to have a regulatory role in autophagy and differentiation as well as endocytic trafficking. ATG24 partially localized on endocytic membranes where it was recruited via PI3-kinase III/VPS34. ATG24 silencing severely impaired receptor-mediated endocytosis of transferrin, but not adsorptive uptake of a lectin, and caused a major enlargement of the flagellar pocket. ATG24 silencing approximately doubled the number of autophagosomes, suggesting a role in repressing autophagy, and strongly accelerated differentiation, in accordance with a role of autophagy in parasite differentiation. Overexpression of the two isoforms of T. brucei ATG8 fused to GFP slowed down differentiation, possibly by a dominant-negative effect. This was overcome by ATG24 depletion, further supporting its regulatory role.
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Affiliation(s)
- Ana Brennand
- Research Unit for Tropical Diseases, de Duve Institute, and Laboratory of Biochemistry, Université catholique de Louvain, Brussels, Belgium
| | - Eva Rico
- Research Unit for Tropical Diseases, de Duve Institute, and Laboratory of Biochemistry, Université catholique de Louvain, Brussels, Belgium
- Departamento de Bioquímica y Biología Molecular, Campus Universitario, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain
| | - Daniel J. Rigden
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
| | | | - Pierre J. Courtoy
- Cell Biology Unit, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Paul A. M. Michels
- Research Unit for Tropical Diseases, de Duve Institute, and Laboratory of Biochemistry, Université catholique de Louvain, Brussels, Belgium
- * E-mail:
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NISHIMURA YUKIO, TAKIGUCHI SOICHI, ITO SHIGERU, ITOH KAZUYUKI. EGF-stimulated AKT activation is mediated by EGFR recycling via an early endocytic pathway in a gefitinib-resistant human lung cancer cell line. Int J Oncol 2015; 46:1721-9. [DOI: 10.3892/ijo.2015.2871] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/23/2014] [Indexed: 11/05/2022] Open
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32
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Kornilova ES. Receptor-mediated endocytosis and cytoskeleton. BIOCHEMISTRY (MOSCOW) 2014; 79:865-78. [DOI: 10.1134/s0006297914090041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Zhang A, He X, Zhang L, Yang L, Woodman P, Li W. Biogenesis of lysosome-related organelles complex-1 subunit 1 (BLOS1) interacts with sorting nexin 2 and the endosomal sorting complex required for transport-I (ESCRT-I) component TSG101 to mediate the sorting of epidermal growth factor receptor into endosomal compartments. J Biol Chem 2014; 289:29180-94. [PMID: 25183008 DOI: 10.1074/jbc.m114.576561] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Biogenesis of lysosome-related organelles complex-1 (BLOC-1) is a component of the molecular machinery required for the biogenesis of specialized organelles and lysosomal targeting of cargoes via the endosomal to lysosomal trafficking pathway. BLOS1, one subunit of BLOC-1, is implicated in lysosomal trafficking of membrane proteins. We found that the degradation and trafficking of epidermal growth factor receptor (EGFR) were delayed in BLOS1 knockdown cells, which were rescued through BLOS1 overexpression. A key feature to the delayed EGFR degradation is the accumulation of endolysosomes in BLOS1 knockdown cells or BLOS1 knock-out mouse embryonic fibroblasts. BLOS1 interacted with SNX2 (a retromer subunit) and TSG101 (an endosomal sorting complex required for transport subunit-I) to mediate EGFR lysosomal trafficking. These results suggest that coordination of the endolysosomal trafficking proteins is important for proper targeting of EGFR to lysosomes.
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Affiliation(s)
- Aili Zhang
- From the State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China, the University of Chinese Academy of Sciences, Beijing 100039, China, and
| | - Xin He
- From the State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ling Zhang
- the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Lin Yang
- From the State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Philip Woodman
- the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Wei Li
- From the State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China,
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Mellado M, Cuartero Y, Brugada R, Verges M. Subcellular localisation of retromer in post-endocytic pathways of polarised Madin-Darby canine kidney cells. Biol Cell 2014; 106:377-93. [PMID: 25081925 DOI: 10.1111/boc.201400011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 07/28/2014] [Indexed: 12/14/2022]
Abstract
BACKGROUND INFORMATION Retromer is required for endosome-to-Golgi retrieval of the cation-independent mannose 6-phosphate receptor (CI-MPR), allowing delivery of hydrolases into lysosomes. It is constituted by a conserved heterotrimer formed by vacuolar protein sorting (Vps) gene products Vps26, Vps35 and Vps29, which is in charge of cargo selection, and a dimer of phosphoinositide-binding sorting nexins (SNXs), which has a structural role. Retromer has been implicated in sorting of additional cargo. Thus, retromer also promotes polymeric immunoglobulin A (pIgA) transcytosis by the pIgA receptor (pIgR) in polarised cells, and considerable evidence implicates retromer in controlling epithelial cell polarity. However, the precise localisation of retromer along the endocytic pathway of polarised cells has not been studied in detail. RESULTS Our biochemical analysis using rat liver endosome fractions suggests a distinct distribution pattern. Although subunits of the cargo-selective complex were enriched in early endosomes (EEs), levels of SNX2 were greater in sorting endosomes. We then immunolocalised the retromer subunits in polarised Madin-Darby canine kidney (MDCK) cells by confocal microscopy. An estimated 25% of total Vps26 and SNX2 localised to EEs, with negligible portions in recycling endosomes as well as in late endosomes and lysosomes. Although Vps26 was in structures of more heterogeneous size and shape than SNX2, these markedly overlapped. In consequence, the two retromer subcomplexes mostly colocalised. When we analysed retromer overlap with its cargo, we found that structures retromer and pIgA(+) are independent of those structures retromer and CI-MPR(+) . Remarkably, retromer localised preferentially at the transcytotic pathway. Pharmacological inhibition of phosphoinositide 3-kinase affected the co-distribution of retromer with pIgA and the CI-MPR, delaying pIgA progress to the apical surface. CONCLUSIONS In polarised MDCK cells, we found retromer associated with certain specialised EE-derived pathways. Our data imply that retromer is largely engaged in pIgA transcytosis in pIgR-expressing MDCK cells, as opposed to endosome-to-Golgi retrieval.
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Affiliation(s)
- Maravillas Mellado
- Laboratory of Epithelial Cell Biology, Príncipe Felipe Research Center (CIPF), Valencia, 46012, Spain
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Nishimura Y, Takiguchi S, Ito S, Itoh K. Evidence that depletion of the sorting nexin 1 by siRNA promotes HGF-induced MET endocytosis and MET phosphorylation in a gefitinib-resistant human lung cancer cell line. Int J Oncol 2013; 44:412-26. [PMID: 24297483 DOI: 10.3892/ijo.2013.2194] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/22/2013] [Indexed: 11/05/2022] Open
Abstract
The receptor tyrosine kinase MET and its ligand HGF are known to be overexpressed in malignant tumor cells, and they have been implicated in gefitinib resistance in lung cancer cells. We recently found that sorting nexin 1 (SNX1), a protein that interacts with EGFR, exhibited negative regulation of EGFR trafficking out of early to late endosomes in gefitinib-resistant NSCLC cell lines. To investigate the role of SNX1 on HGF-stimulated MET endocytosis and its downregulation via the early/late endocytic pathway, we examined the effect of depletion of SNX1 expression by siRNA in NSCLC cells. Using immunofluorescence, we found that the silencing of SNX1 by siRNA caused a dramatic change in the intracellular distribution of plasma membrane-associated MET and that the resultant MET staining was spread throughout the cytoplasm, and it co-localized well with the endocytosed Texas red-labeled transferrin in the siRNA-SNX1-transfected cells. We also found efficient MET phosphorylation and rapid endocytic delivery of phosphorylated MET from early endosomes to late endosomes in the siRNA-SNX1-transfected cells. By contrast, the siRNA-control transfected cells showed inefficient endocytic delivery of phosphorylated MET from early endosomes to late endosomes. Furthermore, large amounts of phosphorylated MET that had accumulated in late endosomes were seen even after 60 min of HGF-stimulation in the presence of bafilomycin A1, indicating that degradation of phosphorylated MET proceeds in a late endosome/lysosome pathway. Western blot analysis revealed that depletion of SNX1 by siRNA induced a maximal and dramatic increase in phosphorylated MET at 60 min, followed by an accelerated degradation of phosphorylated MET after HGF stimulation in the cells. Taken together, we suggest that SNX1 plays a suppressive role in the regulation of HGF-stimulated MET/phosphorylated MET endocytosis and downregulation via the early/late endocytic pathway in the gefitinib-resistant NSCLC cells.
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Affiliation(s)
- Yukio Nishimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Soichi Takiguchi
- Institute for Clinical Research, National Kyushu Cancer Center, Fukuoka 811-1395, Japan
| | - Shigeru Ito
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo 101-0062, Japan
| | - Kazuyuki Itoh
- Department of Biology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka 537-8511, Japan
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36
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Fukaya M, Fukushima D, Hara Y, Sakagami H. EFA6A, a guanine nucleotide exchange factor for Arf6, interacts with sorting nexin-1 and regulates neurite outgrowth. J Neurochem 2013; 129:21-36. [PMID: 24261326 DOI: 10.1111/jnc.12524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/09/2013] [Accepted: 11/04/2013] [Indexed: 01/11/2023]
Abstract
The membrane trafficking and actin cytoskeleton remodeling mediated by ADP ribosylation factor 6 (Arf6) are functionally linked to various neuronal processes including neurite formation and maintenance, neurotransmitter release, and receptor internalization. EFA6A is an Arf6-specific guanine nucleotide exchange factor that is abundantly expressed in the brain. In this study, we identified sorting nexin-1 (SNX1), a retromer component that is implicated in endosomal sorting and trafficking, as a novel interacting partner for EFA6A by yeast two-hybrid screening. The interaction was mediated by the C-terminal region of EFA6A and a BAR domain of SNX1, and further confirmed by pull-down assay and immunoprecipitation from mouse brain lysates. In situ hybridization analysis demonstrated the widespread expression of SNX1 in the mouse brain, which overlapped with the expression of EFA6A in the forebrain. Immunofluorescent analysis revealed the partial colocalization of EFA6A and SNX1 in the dendritic fields of the hippocampus. Immunoelectron microscopic analysis revealed the overlapping subcellular localization of EFA6A and SNX1 at the post-synaptic density and endosomes in dendritic spines. In Neuro-2a neuroblastoma cells, expression of either EFA6A or SNX1 induced neurite outgrowth, which was further enhanced by co-expression of EFA6A and SNX1. The present findings suggest a novel mechanism by which EFA6A regulates Arf6-mediated neurite formation through the interaction with SNX1.
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Affiliation(s)
- Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
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37
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Offringa R, Huang F. Phosphorylation-dependent trafficking of plasma membrane proteins in animal and plant cells. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:789-808. [PMID: 23945267 DOI: 10.1111/jipb.12096] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/02/2013] [Indexed: 05/27/2023]
Abstract
In both unicellular and multicellular organisms, transmembrane (TM) proteins are sorted to and retained at specific membrane domains by endomembrane trafficking mechanisms that recognize sorting signals in the these proteins. The trafficking and distribution of plasma membrane (PM)-localized TM proteins (PM proteins), especially of those PM proteins that show an asymmetric distribution over the PM, has received much attention, as their proper PM localization is crucial for elementary signaling and transport processes, and defects in their localization often lead to severe disease symptoms or developmental defects. The subcellular localization of PM proteins is dynamically regulated by post-translational modifications, such as phosphorylation and ubiquitination. These modificaitons mostly occur on sorting signals that are located in the larger cytosolic domains of the cargo proteins. Here we review the effects of phosphorylation of PM proteins on their trafficking, and present the key examples from the animal field that have been subject to studies for already several decades, such as that of aquaporin 2 and the epidermal growth factor receptor. Our knowledge on cargo trafficking in plants is largely based on studies of the family of PIN FORMED (PIN) carriers that mediate the efflux of the plant hormone auxin. We will review what is known on the subcellular distribution and trafficking of PIN proteins, with a focus on how this is modulated by phosphorylation, and identify and discuss analogies and differences in trafficking with the well-studied animal examples.
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Affiliation(s)
- Remko Offringa
- Molecular and Developmental Genetics, Institute Biology Leiden, Sylvius Laboratory, Sylviusweg 72, 2333 BE Leiden, Leiden University, The Netherlands
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38
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Diss G, Dubé AK, Boutin J, Gagnon-Arsenault I, Landry CR. A systematic approach for the genetic dissection of protein complexes in living cells. Cell Rep 2013; 3:2155-67. [PMID: 23746448 DOI: 10.1016/j.celrep.2013.05.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/11/2013] [Accepted: 05/04/2013] [Indexed: 01/23/2023] Open
Abstract
Cells contain many important protein complexes involved in performing and regulating structural, metabolic, and signaling functions. One major challenge in cell biology is to elucidate the organization and mechanisms of robustness of these complexes in vivo. We developed a systematic approach to study structural dependencies within complexes in living cells by deleting subunits and measuring pairwise interactions among other components. We used our methodology to perturb two conserved eukaryotic complexes: the retromer and the nuclear pore complex. Our results identify subunits that are critical for the assembly of these complexes, reveal their structural architecture, and uncover mechanisms by which protein interactions are modulated. Our results also show that paralogous proteins play a key role in the robustness of protein complexes and shape their assembly landscape. Our approach paves the way for studying the response of protein interactomes to mutations and enhances our understanding of genotype-phenotype maps.
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Affiliation(s)
- Guillaume Diss
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC G1V 0A6, Canada
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39
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Sun Y, Hedman AC, Tan X, Schill NJ, Anderson RA. Endosomal type Iγ PIP 5-kinase controls EGF receptor lysosomal sorting. Dev Cell 2013; 25:144-55. [PMID: 23602387 DOI: 10.1016/j.devcel.2013.03.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 01/24/2013] [Accepted: 03/15/2013] [Indexed: 12/24/2022]
Abstract
Endosomal trafficking and degradation of epidermal growth factor receptor (EGFR) play an essential role in the control of its signaling. Phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P(2)) is an established regulator of endocytosis, whereas PtdIns3P modulates endosomal trafficking. However, we demonstrate here that type I gamma phosphatidylinositol phosphate 5-kinase i5 (PIPKIγi5), an enzyme that synthesizes PtdIns4,5P(2), controls endosome-to-lysosome sorting of EGFR. In this pathway, PIPKIγi5 interacts with sorting nexin 5 (SNX5), a protein that binds PtdIns4,5P(2) and other phosphoinositides. PIPKIγi5 and SNX5 localize to endosomes, and loss of either protein blocks EGFR sorting into intraluminal vesicles (ILVs) of the multivesicular body. Loss of ILV sorting greatly enhances and prolongs EGFR signaling. PIPKIγi5 and SNX5 prevent Hrs ubiquitination, and this facilitates the Hrs association with EGFR that is required for ILV sorting. These findings reveal that PIPKIγi5 and SNX5 form a signaling nexus that controls EGFR endosomal sorting, degradation, and signaling.
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Affiliation(s)
- Yue Sun
- University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, USA
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40
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Ogi S, Fujita H, Kashihara M, Yamamoto C, Sonoda K, Okamoto I, Nakagawa K, Ohdo S, Tanaka Y, Kuwano M, Ono M. Sorting nexin 2-mediated membrane trafficking of c-Met contributes to sensitivity of molecular-targeted drugs. Cancer Sci 2013; 104:573-83. [PMID: 23360489 DOI: 10.1111/cas.12117] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 12/20/2022] Open
Abstract
The sorting nexin (SNX) family is a diverse group of cytoplasmic and membrane-associated proteins that are involved in membrane-trafficking steps within the endocytotic network. SNX1 and SNX2 are components of the mammalian retromer complex and they also play critical roles in the membrane trafficking of growth factor receptors including epidermal growth factor receptor (EGFR) and c-Met. The human lung cancer cell lines, which harbor activating mutations in the kinase domain of EGFR gene, are sensitive to EGFR-targeted drugs gefitinib or erlotinib. However, a lung cancer cell line harboring gene amplification of c-Met is sensitive to the c-Met-targeted drug SU11274 but not to EGFR-targeted drugs. C-Met overexpression is identified as one of the bypass mechanisms for acquired resistance to EGFR-targeted drugs. Here we show that the siRNA-mediated knockdown of SNX2 decreases the cell-surface localization of c-Met, but not that of EGFR, resulting in lysosomal degradation of the c-Met protein. SNX2 specifically interacts with c-Met and treatment with lysosomal inhibitors almost completely annihilates downregulation of c-Met protein by SNX2 knockdown. Therefore, silencing of SNX2 markedly alters sensitivity to anticancer drugs targeted to c-Met (SU11274) and EGFR (gefitinib and erlotinib) through promotion of compensatory activation of the EGFR pathway in lung cancer cells. These findings suggest that development of drugs targeting SNX2 could be useful in overcoming drug resistance to EGFR-targeted drugs in lung cancer cells harboring c-Met gene amplification.
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Affiliation(s)
- Sayaka Ogi
- Department of Pharmaceutical Oncology, Kyushu University, Fukuoka, Japan
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41
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Aubry L, Klein G. True arrestins and arrestin-fold proteins: a structure-based appraisal. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:21-56. [PMID: 23764049 DOI: 10.1016/b978-0-12-394440-5.00002-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Arrestin-clan proteins are folded alike, a feature responsible for their recent grouping in a single clan. In human, it includes the well-characterized visual and β-arrestins, the arrestin domain-containing proteins (ARRDCs), isoforms of the retromer subunit VPS26, and DSCR3, a protein involved in Down syndrome. A new arrestin-fold-predicted protein, RGP1, described here may join the clan. Unicellular organisms like the yeast Saccharomyces cerevisiae or the amoeba Dictyostelium discoideum harbor VPS26, DSCR3, and RGP1 isoforms as well as arrestin-related trafficking adaptors or ADCs, but true arrestins are missing. Functionally, members of the arrestin clan have generally a scaffolding role in various membrane protein trafficking events. Despite their similar structure, the mechanism of cargo recognition and internalization and the nature of recruited partners differ for the different members. Based on the recent literature, true arrestins (visual and β-arrestins), ARRDCs, and yeast ARTS are the closest from a functional point of view.
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Affiliation(s)
- Laurence Aubry
- CEA, IRTSV, Laboratoire Biologie à Grande Echelle, F-38054, Grenoble, France
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42
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NISHIMURA YUKIO, TAKIGUCHI SOICHI, YOSHIOKA KIYOKO, NAKABEPPU YUSAKU, ITOH KAZUYUKI. Silencing of SNX1 by siRNA stimulates the ligand-induced endocytosis of EGFR and increases EGFR phosphorylation in gefitinib-resistant human lung cancer cell lines. Int J Oncol 2012; 41:1520-30. [DOI: 10.3892/ijo.2012.1578] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 07/06/2012] [Indexed: 11/06/2022] Open
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43
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Dores MR, Paing MM, Lin H, Montagne WA, Marchese A, Trejo J. AP-3 regulates PAR1 ubiquitin-independent MVB/lysosomal sorting via an ALIX-mediated pathway. Mol Biol Cell 2012; 23:3612-23. [PMID: 22833563 PMCID: PMC3442409 DOI: 10.1091/mbc.e12-03-0251] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A GPCR ubiquitin-independent MVB/lysosomal sorting pathway is regulated by the adaptor protein complex-3 (AP-3) and ALIX, a noncanonical ESCRT component. AP-3 binds to a PAR1 C-tail–localized, tyrosine-based motif and mediates PAR1 lysosomal degradation. AP-3 also facilitates PAR1 interaction with ALIX, suggesting that AP-3 functions before PAR1 engagement of ALIX and MVB/lysosomal sorting. The sorting of signaling receptors within the endocytic system is important for appropriate cellular responses. After activation, receptors are trafficked to early endosomes and either recycled or sorted to lysosomes and degraded. Most receptors trafficked to lysosomes are modified with ubiquitin and recruited into an endosomal subdomain enriched in hepatocyte growth factor–regulated tyrosine kinase substrate (HRS), a ubiquitin-binding component of the endosomal-sorting complex required for transport (ESCRT) machinery, and then sorted into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs)/lysosomes. However, not all receptors use ubiquitin or the canonical ESCRT machinery to sort to MVBs/lysosomes. This is exemplified by protease-activated receptor-1 (PAR1), a G protein–coupled receptor for thrombin, which sorts to lysosomes independent of ubiquitination and HRS. We recently showed that the adaptor protein ALIX binds to PAR1, recruits ESCRT-III, and mediates receptor sorting to ILVs of MVBs. However, the mechanism that initiates PAR1 sorting at the early endosome is not known. We now report that the adaptor protein complex-3 (AP-3) regulates PAR1 ubiquitin-independent sorting to MVBs through an ALIX-dependent pathway. AP-3 binds to a PAR1 cytoplasmic tail–localized tyrosine-based motif and mediates PAR1 lysosomal degradation independent of ubiquitination. Moreover, AP-3 facilitates PAR1 interaction with ALIX, suggesting that AP-3 functions before PAR1 engagement of ALIX and MVB/lysosomal sorting.
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Affiliation(s)
- Michael R Dores
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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44
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Fernandes H, Franklin E, Jollivet F, Bliedtner K, Khan AR. Mapping the interactions between a RUN domain from DENND5/Rab6IP1 and sorting nexin 1. PLoS One 2012; 7:e35637. [PMID: 22558185 PMCID: PMC3338420 DOI: 10.1371/journal.pone.0035637] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 03/19/2012] [Indexed: 12/03/2022] Open
Abstract
Eukaryotic cells have developed a diverse repertoire of Rab GTPases to regulate vesicle trafficking pathways. Together with their effector proteins, Rabs mediate various aspects of vesicle formation, tethering, docking and fusion, but details of the biological roles elicited by effectors are largely unknown. Human Rab6 is involved in the trafficking of vesicles at the level of Golgi via interactions with numerous effector proteins. We have previously determined the crystal structure of Rab6 in complex with DENND5, alternatively called Rab6IP1, which comprises two RUN domains (RUN1 and RUN2) separated by a PLAT domain. The structure of Rab6/RUN1-PLAT (Rab6/R1P) revealed the molecular basis for Golgi recruitment of DENND5 via the RUN1 domain, but the functional role of the RUN2 domain has not been well characterized. Here we show that a soluble DENND5 construct encompassing the RUN2 domain binds to the N-terminal region of sorting nexin 1 by surface plasmon resonance analyses.
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Affiliation(s)
| | - Edward Franklin
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
| | - Florence Jollivet
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
| | | | - Amir R. Khan
- School of Biochemistry and Immunology, Trinity College, Dublin, Ireland
- * E-mail:
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45
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Berger P, Tersar K, Ballmer-Hofer K, Suter U. The CMT4B disease-causing proteins MTMR2 and MTMR13/SBF2 regulate AKT signalling. J Cell Mol Med 2012; 15:307-15. [PMID: 19912440 PMCID: PMC3822797 DOI: 10.1111/j.1582-4934.2009.00967.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Charcot-Marie-Tooth disease type 4B is caused by mutations in the genes encoding either the lipid phosphatase myotubularin-related protein-2 (MTMR2) or its regulatory binding partner MTMR13/SBF2. Mtmr2 dephosphorylates PI-3-P and PI-3,5-P2 to form phosphatidylinositol and PI-5-P, respectively, while Mtmr13/Sbf2 is an enzymatically inactive member of the myotubularin protein family. We have found altered levels of the critical signalling protein AKT in mouse mutants for Mtmr2 and Mtmr13/Sbf2. Thus, we analysed the influence of Mtmr2 and Mtmr13/Sbf2 on signalling processes. We found that overexpression of Mtmr2 prevents the degradation of the epidermal growth factor receptor (EGFR) and leads to sustained Akt activation whereas Erk activation is not affected. Mtmr13/Sbf2 counteracts the blockage of EGFR degradation without affecting prolonged Akt activation. Our data indicate that Mtmr2 and Mtmr13/Sbf2 play critical roles in the sorting and modulation of cellular signalling which are likely to be disturbed in CMT4B.
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Affiliation(s)
- Philipp Berger
- Molecular Cell Biology, Paul Scherrer Institut, Villigen, Switzerland
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46
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Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease. Biochem J 2011; 441:39-59. [DOI: 10.1042/bj20111226] [Citation(s) in RCA: 212] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.
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47
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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: 99] [Impact Index Per Article: 7.1] [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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48
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Swarbrick JD, Shaw DJ, Chhabra S, Ghai R, Valkov E, Norwood SJ, Seaman MNJ, Collins BM. VPS29 is not an active metallo-phosphatase but is a rigid scaffold required for retromer interaction with accessory proteins. PLoS One 2011; 6:e20420. [PMID: 21629666 PMCID: PMC3101248 DOI: 10.1371/journal.pone.0020420] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 05/02/2011] [Indexed: 11/19/2022] Open
Abstract
VPS29 is a key component of the cargo-binding core complex of retromer, a protein assembly with diverse roles in transport of receptors within the endosomal system. VPS29 has a fold related to metal-binding phosphatases and mediates interactions between retromer and other regulatory proteins. In this study we examine the functional interactions of mammalian VPS29, using X-ray crystallography and NMR spectroscopy. We find that although VPS29 can coordinate metal ions Mn(2+) and Zn(2+) in both the putative active site and at other locations, the affinity for metals is low, and lack of activity in phosphatase assays using a putative peptide substrate support the conclusion that VPS29 is not a functional metalloenzyme. There is evidence that structural elements of VPS29 critical for binding the retromer subunit VPS35 may undergo both metal-dependent and independent conformational changes regulating complex formation, however studies using ITC and NMR residual dipolar coupling (RDC) measurements show that this is not the case. Finally, NMR chemical shift mapping indicates that VPS29 is able to associate with SNX1 via a conserved hydrophobic surface, but with a low affinity that suggests additional interactions will be required to stabilise the complex in vivo. Our conclusion is that VPS29 is a metal ion-independent, rigid scaffolding domain, which is essential but not sufficient for incorporation of retromer into functional endosomal transport assemblies.
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Affiliation(s)
- James D. Swarbrick
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Daniel J. Shaw
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Sandeep Chhabra
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Rajesh Ghai
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Eugene Valkov
- School of Chemistry and Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Suzanne J. Norwood
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
| | - Matthew N. J. Seaman
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Cambridge University, Cambridge, United Kingdom
| | - Brett M. Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
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49
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Cui Y, Li X, Chen Q, He X, Yang Q, Zhang A, Yu X, Chen H, Liu N, Xie Q, Yang W, Zuo J, Palme K, Li W. BLOS1, a putative BLOC-1 subunit, interacts with SNX1 and modulates root growth in Arabidopsis. J Cell Sci 2011; 123:3727-33. [PMID: 20971704 DOI: 10.1242/jcs.069732] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Internalization and sorting of macromolecules are inherent properties of all eukaryotic cells that are achieved by vesicle trafficking. However, this process is relatively less understood in plants. An eight-subunit protein complex, BLOC-1, which is involved in endosomal transport from the endosomes to the lysosomes, has been identified in both human and mice. In this study, two homologous subunits of this complex, BLOS1 (or AtGCN5L1) and BLOS2, have been characterized in Arabidopsis. Both BLOS1 and BLOS2 interacted with SNX1 on the sorting endosomes. Inducible RNAi lines with reduced levels of BLOS1 had longer primary roots and more lateral roots. Consistently, PIN1 and PIN2 were increased in BLOS1 RNAi lines, implicating an impaired transport from the endosomes to the vacuoles. These results suggest that a putative BLOC-1 complex in Arabidopsis might mediate the vacuolar degradative transport through direct interaction with SNX1 to regulate the homeostasis of PIN1 and PIN2, which is important for plant growth and development.
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Affiliation(s)
- Yanyan Cui
- Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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50
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Rincón E, de Guinoa JS, Gharbi SI, Sorzano COS, Carrasco YR, Mérida I. Translocation dynamics of sorting nexin 27 in activated T cells. J Cell Sci 2011; 124:776-88. [DOI: 10.1242/jcs.072447] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Sorting nexin 27 (SNX27) belongs to the sorting nexin family of proteins, which participate in vesicular and protein trafficking. Similarly to all sorting nexin proteins, SNX27 has a functional PX domain that is important for endosome binding, but it is the only sorting nexin with a PDZ domain. We identified SNX27 as a partner of diacylglycerol kinase ζ (DGKζ), a negative regulator of T cell function that metabolises diacylglycerol to yield phosphatidic acid. SNX27 interacts with the DGKζ PDZ-binding motif in early/recycling endosomes in resting T cells; however, the dynamics and mechanisms underlying SNX27 subcellular localisation during T cell activation are unknown. We demonstrate that in T cells that encounter pulsed antigen-presenting cells, SNX27 in transit on early/recycling endosomes polarise to the immunological synapse. A fraction of SNX27 accumulates at the mature immunological synapse in a process that is dependent on vesicular trafficking, binding of the PX domain to phosphatidylinositol 3-phosphate and the presence of the PDZ region. Downmodulation of expression of either SNX27 or DGKζ results in enhanced basal and antigen-triggered ERK phosphorylation. These results identify SNX27 as a PDZ-containing component of the T cell immunological synapse, and demonstrate a role for this protein in the regulation of the Ras–ERK pathway, suggesting a functional relationship between SNX27 and DGKζ.
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Affiliation(s)
- Esther Rincón
- Lipid signalling Laboratory, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
| | - Julia Sáez de Guinoa
- B cell Dynamics Laboratory, Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
| | - Severine I. Gharbi
- Lipid signalling Laboratory, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
| | - Carlos O. S. Sorzano
- Biocomputing Unit, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
| | - Yolanda R. Carrasco
- B cell Dynamics Laboratory, Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
| | - Isabel Mérida
- Lipid signalling Laboratory, Centro Nacional de Biotecnología (CNB)/CSIC, E-28049 Madrid, Spain
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