1
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Morgens DW, Gulyas L, Rivera-Madera A, Souza AS, Glaunsinger BA. From enhancers to genome conformation: complex transcriptional control underlies expression of a single herpesviral gene. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.08.548212. [PMID: 37461644 PMCID: PMC10350069 DOI: 10.1101/2023.07.08.548212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Complex transcriptional control is a conserved feature of both eukaryotes and the viruses that infect them. Here, we illustrate this by combining high-density functional genomics, expression profiling, and viral-specific chromosome conformation capture to define with unprecedented detail the transcriptional regulation of a single gene, ORF68, from Kaposi's sarcoma-associated herpesvirus (KSHV). We first identified seven cis-regulatory regions by densely tiling the ~154 kb KSHV genome with CRISPRi. A parallel Cas9 nuclease screen indicated that three of these regions act as promoters of genes that regulate ORF68. RNA expression profiling demonstrated that three more of these regions act by either repressing or enhancing other distal viral genes involved in ORF68 transcriptional regulation. Finally, we tracked how the 3D structure of the viral genome changes during its lifecycle, revealing that these enhancing regulatory elements are physically closer to their targets when active, and that disrupting some elements caused large-scale changes to the 3D genome. These data enable us to construct a complete model revealing that the mechanistic diversity of this essential regulatory circuit matches that of human genes.
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Affiliation(s)
- David W Morgens
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Leah Gulyas
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | | | | | - Britt A Glaunsinger
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
- Department of Molecular and Cell Biology, UC Berkeley, CA, USA
- Howard Hughes Medical Institute, UC Berkeley, CA, USA
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2
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Tsui CK, Twells N, Doan E, Woo J, Khosrojerdi N, Brooks J, Kulepa A, Webster B, Mahal LK, Dillin A. CRISPR screens and lectin microarrays identify novel high mannose N-glycan regulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.23.563662. [PMID: 37961200 PMCID: PMC10634773 DOI: 10.1101/2023.10.23.563662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Glycans play critical roles in cellular signaling and function. Unlike proteins, glycan structures are not templated from genes but the concerted activity of many genes, making them historically challenging to study. Here, we present a strategy that utilizes pooled CRISPR screens and lectin microarrays to uncover and characterize regulators of cell surface glycosylation. We applied this approach to study the regulation of high mannose glycans - the starting structure of all asparagine(N)-linked-glycans. We used CRISPR screens to uncover the expanded network of genes controlling high mannose surface levels, followed by lectin microarrays to fully measure the complex effect of select regulators on glycosylation globally. Through this, we elucidated how two novel high mannose regulators - TM9SF3 and the CCC complex - control complex N-glycosylation via regulating Golgi morphology and function. Notably, this method allowed us to interrogate Golgi function in-depth and reveal that similar disruption to Golgi morphology can lead to drastically different glycosylation outcomes. Collectively, this work demonstrates a generalizable approach for systematically dissecting the regulatory network underlying glycosylation.
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Affiliation(s)
- C Kimberly Tsui
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicholas Twells
- Department of Chemistry, University of Alberta, Edmonton, Canada, T6G 2G2
| | - Emma Doan
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jacqueline Woo
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Noosha Khosrojerdi
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Janiya Brooks
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ayodeji Kulepa
- Department of Chemistry, University of Alberta, Edmonton, Canada, T6G 2G2
| | - Brant Webster
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Lara K Mahal
- Department of Chemistry, University of Alberta, Edmonton, Canada, T6G 2G2
| | - Andrew Dillin
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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3
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Bingham R, McCarthy H, Buckley N. Exploring Retrograde Trafficking: Mechanisms and Consequences in Cancer and Disease. Traffic 2024; 25:e12931. [PMID: 38415291 DOI: 10.1111/tra.12931] [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: 11/29/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 02/29/2024]
Abstract
Retrograde trafficking (RT) orchestrates the intracellular movement of cargo from the plasma membrane, endosomes, Golgi or endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) in an inward/ER-directed manner. RT works as the opposing movement to anterograde trafficking (outward secretion), and the two work together to maintain cellular homeostasis. This is achieved through maintaining cell polarity, retrieving proteins responsible for anterograde trafficking and redirecting proteins that become mis-localised. However, aberrant RT can alter the correct location of key proteins, and thus inhibit or indeed change their canonical function, potentially causing disease. This review highlights the recent advances in the understanding of how upregulation, downregulation or hijacking of RT impacts the localisation of key proteins in cancer and disease to drive progression. Cargoes impacted by aberrant RT are varied amongst maladies including neurodegenerative diseases, autoimmune diseases, bacterial and viral infections (including SARS-CoV-2), and cancer. As we explore the intricacies of RT, it becomes increasingly apparent that it holds significant potential as a target for future therapies to offer more effective interventions in a wide range of pathological conditions.
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Affiliation(s)
- Rachel Bingham
- School of Pharmacy, Queen's University Belfast, Belfast, UK
| | - Helen McCarthy
- School of Pharmacy, Queen's University Belfast, Belfast, UK
| | - Niamh Buckley
- School of Pharmacy, Queen's University Belfast, Belfast, UK
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4
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Replogle JM, Bonnar JL, Pogson AN, Liem CR, Maier NK, Ding Y, Russell BJ, Wang X, Leng K, Guna A, Norman TM, Pak RA, Ramos DM, Ward ME, Gilbert LA, Kampmann M, Weissman JS, Jost M. Maximizing CRISPRi efficacy and accessibility with dual-sgRNA libraries and optimal effectors. eLife 2022; 11:e81856. [PMID: 36576240 PMCID: PMC9829409 DOI: 10.7554/elife.81856] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
CRISPR interference (CRISPRi) enables programmable, reversible, and titratable repression of gene expression (knockdown) in mammalian cells. Initial CRISPRi-mediated genetic screens have showcased the potential to address basic questions in cell biology, genetics, and biotechnology, but wider deployment of CRISPRi screening has been constrained by the large size of single guide RNA (sgRNA) libraries and challenges in generating cell models with consistent CRISPRi-mediated knockdown. Here, we present next-generation CRISPRi sgRNA libraries and effector expression constructs that enable strong and consistent knockdown across mammalian cell models. First, we combine empirical sgRNA selection with a dual-sgRNA library design to generate an ultra-compact (1-3 elements per gene), highly active CRISPRi sgRNA library. Next, we compare CRISPRi effectors to show that the recently published Zim3-dCas9 provides an excellent balance between strong on-target knockdown and minimal non-specific effects on cell growth or the transcriptome. Finally, we engineer a suite of cell lines with stable expression of Zim3-dCas9 and robust on-target knockdown. Our results and publicly available reagents establish best practices for CRISPRi genetic screening.
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Affiliation(s)
- Joseph M Replogle
- Medical Scientist Training Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Jessica L Bonnar
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Angela N Pogson
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Christina R Liem
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Nolan K Maier
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Yufang Ding
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Baylee J Russell
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Xingren Wang
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Kun Leng
- Medical Scientist Training Program, University of California, San FranciscoSan FranciscoUnited States
- Institute for Neurodegenerative Disease, University of California, San FranciscoSan FranciscoUnited States
| | - Alina Guna
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Thomas M Norman
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Ryan A Pak
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Daniel M Ramos
- Center for Alzheimer's Disease and Related Dementias, National Institutes of HealthBethesdaUnited States
- National Institute on Aging, National Institutes of HealthBethesdaUnited States
| | - Michael E Ward
- National Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaUnited States
| | - Luke A Gilbert
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California, San FranciscoSan FranciscoUnited States
- Arc InstitutePalo AltoUnited States
| | - Martin Kampmann
- Institute for Neurodegenerative Disease, University of California, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Whitehead Institute for Biomedical ResearchCambridgeUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Marco Jost
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
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5
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Fry MY, Najdrová V, Maggiolo AO, Saladi SM, Doležal P, Clemons WM. Structurally derived universal mechanism for the catalytic cycle of the tail-anchored targeting factor Get3. Nat Struct Mol Biol 2022; 29:820-830. [DOI: 10.1038/s41594-022-00798-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/26/2022] [Indexed: 11/09/2022]
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6
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Sandvig K, Kavaliauskiene S, Myrann AG, Iversen TG, Skotland T. Modulation of Ricin Intoxication by the Autophagy Inhibitor EACC. Toxins (Basel) 2022; 14:toxins14050360. [PMID: 35622606 PMCID: PMC9145485 DOI: 10.3390/toxins14050360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 02/04/2023] Open
Abstract
The compound EACC (ethyl (2-(5-nitrothiophene-2-carboxamido) thiophene-3-carbonyl) carbamate) was recently reported to inhibit fusion of autophagosomes with lysosomes in a reversible manner by inhibiting recruitment of syntaxin 17 to autophagosomes. We report here that this compound also provides a strong protection against the protein toxin ricin as well as against other plant toxins such as abrin and modeccin. The protection did not seem to be caused by inhibition of endocytosis and retrograde transport, but rather by inhibited release of the enzymatically active A-moiety to the cytosol. The TANK-binding kinase 1 (TBK1) has been reported to phosphorylate syntaxin 17 and be required for initiation of autophagy. The inhibitor of TBK1, MRT68601, induced in itself a strong sensitization to ricin, apparently by increasing transport to the Golgi apparatus. Importantly, MRT68601 increased Golgi transport of ricin even in the presence of EACC, but EACC was still able to inhibit intoxication, supporting the idea that EACC protects at a late step along the retrograde pathway. These results also indicate that phosphorylation of syntaxin 17 is not required for the protection observed.
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Affiliation(s)
- Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; (S.K.); (A.G.M.); (T.G.I.); (T.S.)
- Department of Biosciences, University of Oslo, 0315 Oslo, Norway
- Correspondence:
| | - Simona Kavaliauskiene
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; (S.K.); (A.G.M.); (T.G.I.); (T.S.)
- Institute for Experimental Medical Research, University of Oslo and Oslo University Hospital Ullevål, 0450 Oslo, Norway
| | - Anne Grethe Myrann
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; (S.K.); (A.G.M.); (T.G.I.); (T.S.)
| | - Tore Geir Iversen
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; (S.K.); (A.G.M.); (T.G.I.); (T.S.)
| | - Tore Skotland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway; (S.K.); (A.G.M.); (T.G.I.); (T.S.)
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7
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Veale CGL, Talukdar A, Vauzeilles B. ICBS 2021: Looking Toward the Next Decade of Chemical Biology. ACS Chem Biol 2022; 17:728-743. [PMID: 35293726 DOI: 10.1021/acschembio.2c00209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Clinton G. L. Veale
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa
| | - Arindam Talukdar
- Department of Organic and Medicinal Chemistry, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, West Bengal, India
| | - Boris Vauzeilles
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198, Gif-sur-Yvette, France
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8
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Keszei AF, Yip MC, Hsieh TC, Shao S. Structural insights into metazoan pretargeting GET complexes. Nat Struct Mol Biol 2021; 28:1029-1037. [PMID: 34887561 PMCID: PMC9477564 DOI: 10.1038/s41594-021-00690-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 10/20/2021] [Indexed: 11/09/2022]
Abstract
Close coordination between chaperones is essential for protein biosynthesis, including the delivery of tail-anchored (TA) proteins containing a single C-terminal transmembrane domain to the endoplasmic reticulum (ER) by the conserved GET pathway. For successful targeting, nascent TA proteins must be promptly chaperoned and loaded onto the cytosolic ATPase Get3 through a transfer reaction involving the chaperone SGTA and bridging factors Get4, Ubl4a and Bag6. Here, we report cryo-electron microscopy structures of metazoan pretargeting GET complexes at 3.3-3.6 Å. The structures reveal that Get3 helix 8 and the Get4 C terminus form a composite lid over the Get3 substrate-binding chamber that is opened by SGTA. Another interaction with Get4 prevents formation of Get3 helix 4, which links the substrate chamber and ATPase domain. Both interactions facilitate TA protein transfer from SGTA to Get3. Our findings show how the pretargeting complex primes Get3 for coordinated client loading and ER targeting.
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Affiliation(s)
- Alexander F.A. Keszei
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, 240 Longwood Ave., Boston, MA 02115
| | - Matthew C.J. Yip
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, 240 Longwood Ave., Boston, MA 02115
| | - Ta-Chien Hsieh
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, 240 Longwood Ave., Boston, MA 02115,Massachusetts College of Pharmacy and Health Sciences, 179 Longwood Ave., Boston, MA 02115
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA, USA.
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9
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Rudolph MJ, Poon AY, Kavaliauskiene S, Myrann AG, Reynolds-Peterson C, Davis SA, Sandvig K, Vance DJ, Mantis NJ. Structural Analysis of Toxin-Neutralizing, Single-Domain Antibodies that Bridge Ricin's A-B Subunit Interface. J Mol Biol 2021; 433:167086. [PMID: 34089718 DOI: 10.1016/j.jmb.2021.167086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/18/2021] [Accepted: 05/27/2021] [Indexed: 01/20/2023]
Abstract
Ricin toxin kills mammalian cells with notorious efficiency. The toxin's B subunit (RTB) is a Gal/GalNAc-specific lectin that attaches to cell surfaces and promotes retrograde transport of ricin's A subunit (RTA) to the trans Golgi network (TGN) and endoplasmic reticulum (ER). RTA is liberated from RTB in the ER and translocated into the cell cytoplasm, where it functions as a ribosome-inactivating protein. While antibodies against ricin's individual subunits have been reported, we now describe seven alpaca-derived, single-domain antibodies (VHHs) that span the RTA-RTB interface, including four Tier 1 VHHs with IC50 values <1 nM. Crystal structures of each VHH bound to native ricin holotoxin revealed three different binding modes, based on contact with RTA's F-G loop (mode 1), RTB's subdomain 2γ (mode 2) or both (mode 3). VHHs in modes 2 and 3 were highly effective at blocking ricin attachment to HeLa cells and immobilized asialofetuin, due to framework residues (FR3) that occupied the 2γ Gal/GalNAc-binding pocket and mimic ligand. The four Tier 1 VHHs also interfered with intracellular functions of RTB, as they neutralized ricin in a post-attachment cytotoxicity assay (e.g., the toxin was bound to cell surfaces before antibody addition) and reduced the efficiency of toxin transport to the TGN. We conclude that the RTA-RTB interface is a target of potent toxin-neutralizing antibodies that interfere with both extracellular and intracellular events in ricin's cytotoxic pathway.
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Affiliation(s)
| | - Amanda Y Poon
- Department of Biomedical Sciences, University at Albany, Albany, NY, USA; Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Simona Kavaliauskiene
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway
| | - Anne Grethe Myrann
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway
| | - Claire Reynolds-Peterson
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Simon A Davis
- New York Structural Biology Center, New York, NY, USA
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway; Department of Biosciences, University of Oslo, Oslo, Norway
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA.
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10
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The Protein Toxins Ricin and Shiga Toxin as Tools to Explore Cellular Mechanisms of Internalization and Intracellular Transport. Toxins (Basel) 2021; 13:toxins13060377. [PMID: 34070659 PMCID: PMC8227415 DOI: 10.3390/toxins13060377] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/12/2021] [Accepted: 05/22/2021] [Indexed: 12/18/2022] Open
Abstract
Protein toxins secreted by bacteria and found in plants can be threats to human health. However, their extreme toxicity can also be exploited in different ways, e.g., to produce hybrid toxins directed against cancer cells and to study transport mechanisms in cells. Investigations during the last decades have shown how powerful these molecules are as tools in cell biological research. Here, we first present a partly historical overview, with emphasis on Shiga toxin and ricin, of how such toxins have been used to characterize processes and proteins of importance for their trafficking. In the second half of the article, we describe how one can now use toxins to investigate the role of lipid classes for intracellular transport. In recent years, it has become possible to quantify hundreds of lipid species using mass spectrometry analysis. Thus, it is also now possible to explore the importance of lipid species in intracellular transport. The detailed analyses of changes in lipids seen under conditions of inhibited toxin transport reveal previously unknown connections between syntheses of lipid classes and demonstrate the ability of cells to compensate under given conditions.
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11
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Treasure T, Nelson CDS. Inhibition of JC polyomavirus infectivity by the retrograde transport inhibitor Retro-2.1. Microbiol Immunol 2020; 64:783-791. [PMID: 32965709 DOI: 10.1111/1348-0421.12851] [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: 02/20/2020] [Revised: 09/02/2020] [Accepted: 09/16/2020] [Indexed: 11/28/2022]
Abstract
JC polyomavirus (JCPyV) is a common human pathogen that results in a chronic asymptomatic infection in healthy adults. Under conditions of immunosuppression, JCPyV spreads to the central nervous system and can cause the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML), a disease for which there are no vaccines or antiviral therapies. Retro-2 is a previously identified small molecule inhibitor that was originally shown to block retrograde transport of toxins such as ricin toxin from endosomes to the Golgi apparatus and endoplasmic reticulum (ER), and Retro-2.1 is a chemical analog of Retro-2 that has been shown to inhibit ricin intoxication of cells at low nanomolar concentrations. Retro-2 has previously been shown to prevent retrograde transport of JCPyV virions to the ER, but the effect of Retro-2.1 on JCPyV infectivity is unknown. Here it is shown that Retro-2.1 inhibits JCPyV with an EC50 of 3.9 μM. This molecule inhibits JCPyV infection at dosages that are not toxic to human tissue culture cells. Retro-2.1 was also tested against two other polyomaviruses, the human BK polyomavirus and simian virus 40, and was also shown to inhibit infection at similar concentrations. Viral uncoating studies demonstrate that Retro-2.1 inhibits BKPyV infectivity in a manner similar to Retro-2. These studies demonstrate that improved analogs of Retro-2 can inhibit infection at lower dosages than Retro-2 and further optimization of these compounds may lead to effective treatment options for those suffering from JCPyV infection and PML.
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Affiliation(s)
- Tashania Treasure
- Department of Biological Sciences, State University of New York, Cortland, Cortland, New York
| | - Christian D S Nelson
- Department of Biological Sciences, State University of New York, Cortland, Cortland, New York
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12
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The macrophage microtubule network acts as a key cellular controller of the intracellular fate of Leishmania infantum. PLoS Negl Trop Dis 2020; 14:e0008396. [PMID: 32722702 PMCID: PMC7386624 DOI: 10.1371/journal.pntd.0008396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/16/2020] [Indexed: 11/19/2022] Open
Abstract
The parasitophorous vacuoles (PVs) that insulate Leishmania spp. in host macrophages are vacuolar compartments wherein promastigote forms differentiate into amastigote that are the replicative form of the parasite and are also more resistant to host responses. We revisited the biogenesis of tight-fitting PVs that insulate L. infantum in promastigote-infected macrophage-like RAW 264.7 cells by time-dependent confocal laser multidimensional imaging analysis. Pharmacological disassembly of the cellular microtubule network and silencing of the dynein gene led to an impaired interaction of L. infantum-containing phagosomes with late endosomes and lysosomes, resulting in the tight-fitting parasite-containing phagosomes never transforming into mature PVs. Analysis of the shape of the L. infantum parasite within PVs, showed that factors that impair promastigote-amastigote differentiation can also result in PVs whose maturation is arrested. These findings highlight the importance of the MT-dependent interaction of L. infantum-containing phagosomes with the host macrophage endolysosomal pathway to secure the intracellular fate of the parasite. Kinetoplastid parasites of the genus Leishmania are responsible for a diverse spectrum of mammalian infectious diseases, the leishmaniases, including cutaneous, mucocutaneous, and mucosal pathologies. Infectious metacyclic promastigotes of infected female Phlebotomus sandflies are injected into the host at the site of the bite during the sandfly blood meal, after which they are internalized by host professional phagocytic neutrophils and macrophages. Leishmania infantum is an etiological agent of potentially fatal visceral pathology. This study molecularly dissects the maturation of L. infantum-containing phagosomes/parasitophorous vacuoles (PVs) in host macrophages. We reveal the requirement of vacuolar movement along macrophage microtubule tracks for the phagosome trafficking toward the endolysosomal pathway necessary for the development of the mature tight-fitting PV crucial for L. infantum survival and proliferation.
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13
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Li XP, Harijan RK, Kahn JN, Schramm VL, Tumer NE. Small Molecule Inhibitors Targeting the Interaction of Ricin Toxin A Subunit with Ribosomes. ACS Infect Dis 2020; 6:1894-1905. [PMID: 32428396 DOI: 10.1021/acsinfecdis.0c00127] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ricin toxin A subunit (RTA) removes an adenine from the universally conserved sarcin/ricin loop (SRL) on eukaryotic ribosomes, thereby inhibiting protein synthesis. No high affinity and selective small molecule therapeutic antidotes have been reported against ricin toxicity. RTA binds to the ribosomal P stalk to access the SRL. The interaction anchors RTA to the P protein C-termini at a well-defined hydrophobic pocket, which is on the opposite face relative to the active site. The RTA ribosome binding site has not been previously targeted by small molecule inhibitors. We used fragment screening with surface plasmon resonance to identify small molecular weight lead compounds that bind RTA and defined their interactions by crystallography. We identified five fragments, which bound RTA with mid-micromolar affinity. Three chemically distinct binding fragments were cocrystallized with RTA, and crystal structures were solved. Two fragments bound at the P stalk binding site, and the third bound to helix D, a motif distinct from the P stalk binding site. All fragments bound RTA remote from the catalytic site and caused little change in catalytic site geometry. Two fragments uniquely bound at the hydrophobic pocket with affinity sufficient to inhibit the catalytic activity on eukaryotic ribosomes in the low micromolar range. The binding mode of these inhibitors mimicked the interaction of the P stalk peptide, establishing that small molecule inhibitors can inhibit RTA binding to the ribosome with the potential for therapeutic intervention.
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Affiliation(s)
- Xiao-Ping Li
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
| | - Rajesh K. Harijan
- Department of Biochemistry, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus,1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Jennifer N. Kahn
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Jack and Pearl Resnick Campus,1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Nilgun E. Tumer
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
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14
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Nicolas V, Lievin-Le Moal V. Small Trafficking Inhibitor Retro-2 Disrupts the Microtubule-Dependent Trafficking of Autophagic Vacuoles. Front Cell Dev Biol 2020; 8:464. [PMID: 32626708 PMCID: PMC7314991 DOI: 10.3389/fcell.2020.00464] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/19/2020] [Indexed: 12/13/2022] Open
Abstract
Autophagy is a catabolic recycling process by which a cell degrades its own constituents to contribute to cell homeostasis or survival. We report that the small trafficking inhibitor Retro-2 impairs microtubule-dependent vacuolar trafficking in autophagy. Retro-2 induced autophagy and promoted the dramatic cytoplasmic accumulation of large autophagosomes. Moreover, Retro-2 decreased the spreading of autophagosomes within the cytoplasm of nutrient-starved cells. In addition, Retro-2 abolished autolysosomes formation. We show that these effects arise from hitherto unsuspected disassembly activity of the small molecule on the cellular microtubule network, which is known to act as a key regulator of vacuolar trafficking of the autophagy pathway.
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Affiliation(s)
- Valérie Nicolas
- Université Paris-Saclay, Institut Paris-Saclay d'Innovation Thérapeutique (IPSIT), Microscope Facility (MIPSIT), UMS-US31-UMS3679, Châtenay-Malabry, France
| | - Vanessa Lievin-Le Moal
- University Paris-Saclay, Inserm, UMR-S 996 Inflammation, Microbiome and Immunosurveillance, Clamart, France
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15
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Targeting the Early Endosome-to-Golgi Transport of Shiga Toxins as a Therapeutic Strategy. Toxins (Basel) 2020; 12:toxins12050342. [PMID: 32456007 PMCID: PMC7290323 DOI: 10.3390/toxins12050342] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 02/07/2023] Open
Abstract
Shiga toxin (STx) produced by Shigella and closely related Shiga toxin 1 and 2 (STx1 and STx2) synthesized by Shiga toxin-producing Escherichia coli (STEC) are bacterial AB5 toxins. All three toxins target kidney cells and may cause life-threatening renal disease. While Shigella infections can be treated with antibiotics, resistance is increasing. Moreover, antibiotic therapy is contraindicated for STEC, and there are no definitive treatments for STEC-induced disease. To exert cellular toxicity, STx, STx1, and STx2 must undergo retrograde trafficking to reach their cytosolic target, ribosomes. Direct transport from early endosomes to the Golgi apparatus is an essential step that allows the toxins to bypass degradative late endosomes and lysosomes. The essentiality of this transport step also makes it an ideal target for the development of small-molecule inhibitors of toxin trafficking as potential therapeutics. Here, we review the recent advances in understanding the molecular mechanisms of the early endosome-to-Golgi transport of STx, STx1, and STx2, as well as the development of small-molecule inhibitors of toxin trafficking that act at the endosome/Golgi interface.
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16
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Cojean S, Nicolas V, Lievin-Le Moal V. Key role of the macrophage microtubule network in the intracellular lifestyle of Leishmania amazonensis. Cell Microbiol 2020; 22:e13218. [PMID: 32406568 DOI: 10.1111/cmi.13218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/11/2020] [Accepted: 04/28/2020] [Indexed: 11/30/2022]
Abstract
We conducted a study to decipher the mechanism of the formation of the large communal Leishmania amazonensis-containing parasitophorous vacuole (PV) and found that the macrophage microtubule (MT) network dynamically orchestrates the intracellular lifestyle of this intracellular parasite. Physical disassembly of the MT network of macrophage-like RAW 264.7 cells or silencing of the dynein gene, encoding the MT-associated molecular motor that powers MT-dependent vacuolar movement, by siRNA resulted in most of the infected cells hosting only tight parasite-containing phagosome-like vacuoles randomly distributed throughout the cytoplasm, each insulating a single parasite. Only a minority of the infected cells hosted both isolated parasite-containing phagosome-like vacuoles and a small communal PV, insulating a maximum of two to three parasites. The tight parasite-containing phagosome-like vacuoles never matured, whereas the small PVs only matured to a small degree, shown by the absence or faint acquisition of host-cell endolysosomal characteristics. As a consequence, the parasites were unable to successfully complete promastigote-to-amastigote differentiation and died, regardless of the type of insulation.
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Affiliation(s)
- Sandrine Cojean
- CNRS, UMR 8076 BioCis, University Paris-Saclay, Châtenay-Malabry, France
| | - Valérie Nicolas
- Institut Paris-Saclay d'Innovation Thérapeutique (IPSIT), UMS -US31 -UMS3679, Microscopy facility (MIPSIT), University Paris-Saclay, Châtenay-Malabry, France
| | - Vanessa Lievin-Le Moal
- Inserm, UMR-S 996 Inflammation, Microbiome and Immunosurveillance, University Paris-Saclay, Clamart, France
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