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Jia W, Yuan J, Li S, Cheng B. The role of dysregulated mRNA translation machinery in cancer pathogenesis and therapeutic value of ribosome-inactivating proteins. Biochim Biophys Acta Rev Cancer 2023; 1878:189018. [PMID: 37944831 DOI: 10.1016/j.bbcan.2023.189018] [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: 09/14/2023] [Revised: 10/17/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023]
Abstract
Dysregulated protein synthesis is a hallmark of tumors. mRNA translation reprogramming contributes to tumorigenesis, which is fueled by abnormalities in ribosome formation, tRNA abundance and modification, and translation factors. Not only malignant cells but also stromal cells within tumor microenvironment can undergo transformation toward tumorigenic phenotypes during translational reprogramming. Ribosome-inactivating proteins (RIPs) have garnered interests for their ability to selectively inhibit protein synthesis and suppress tumor growth. This review summarizes the role of dysregulated translation machinery in tumor development and explores the potential of RIPs in cancer treatment.
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Affiliation(s)
- Wentao Jia
- Oncology Department of Traditional Chinese Medicine, the First Affiliated Hospital of Naval Medical University, Shanghai 200433, China; Faculty of Traditional Chinese Medicine, Naval Medical University, Shanghai 200043, China
| | - Jiaying Yuan
- Department of Pulmonary and Critical Care Medicine, Tongji Hospital, School of Medicine, Tongji University, Shanghai 200065, China
| | - Shu Li
- Department of Gastroenterology, Baoshan Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201900, China.
| | - Binbin Cheng
- Oncology Department of Traditional Chinese Medicine, the First Affiliated Hospital of Naval Medical University, Shanghai 200433, China; Faculty of Traditional Chinese Medicine, Naval Medical University, Shanghai 200043, China.
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2
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Watts NR, Eren E, Palmer I, Huang PL, Huang PL, Shoemaker RH, Lee-Huang S, Wingfield PT. The ribosome-inactivating proteins MAP30 and Momordin inhibit SARS-CoV-2. PLoS One 2023; 18:e0286370. [PMID: 37384752 PMCID: PMC10310010 DOI: 10.1371/journal.pone.0286370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/15/2023] [Indexed: 07/01/2023] Open
Abstract
The continuing emergence of SARS-CoV-2 variants has highlighted the need to identify additional points for viral inhibition. Ribosome inactivating proteins (RIPs), such as MAP30 and Momordin which are derived from bitter melon (Momordica charantia), have been found to inhibit a broad range of viruses. MAP30 has been shown to potently inhibit HIV-1 with minimal cytotoxicity. Here we show that MAP30 and Momordin potently inhibit SARS-CoV-2 replication in A549 human lung cells (IC50 ~ 0.2 μM) with little concomitant cytotoxicity (CC50 ~ 2 μM). Both viral inhibition and cytotoxicity remain unaltered by appending a C-terminal Tat cell-penetration peptide to either protein. Mutation of tyrosine 70, a key residue in the active site of MAP30, to alanine completely abrogates both viral inhibition and cytotoxicity, indicating the involvement of its RNA N-glycosylase activity. Mutation of lysine 171 and lysine 215, residues corresponding to those in Ricin which when mutated prevented ribosome binding and inactivation, to alanine in MAP30 decreased cytotoxicity (CC50 ~ 10 μM) but also the viral inhibition (IC50 ~ 1 μM). Unlike with HIV-1, neither Dexamethasone nor Indomethacin exhibited synergy with MAP30 in the inhibition of SARS-CoV-2. From a structural comparison of the two proteins, one can explain their similar activities despite differences in both their active-sites and ribosome-binding regions. We also note points on the viral genome for potential inhibition by these proteins.
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Affiliation(s)
- Norman R. Watts
- Protein Expression Laboratory, NIAMS, NIH, Bethesda, Maryland, United States of America
| | - Elif Eren
- Protein Expression Laboratory, NIAMS, NIH, Bethesda, Maryland, United States of America
| | - Ira Palmer
- Protein Expression Laboratory, NIAMS, NIH, Bethesda, Maryland, United States of America
| | - Paul L. Huang
- Department of Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Philip Lin Huang
- Department of Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Robert H. Shoemaker
- Chemopreventive Agent Development Research Group, Division of Cancer Prevention, NCI, NIH, Bethesda, Maryland, United States of America
| | - Sylvia Lee-Huang
- Department of Biochemistry and Molecular Pharmacology, New York University, Grossman School of Medicine, New York, New York, United States of America
| | - Paul T. Wingfield
- Protein Expression Laboratory, NIAMS, NIH, Bethesda, Maryland, United States of America
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Lapadula WJ, Juri Ayub M. Ribosome Inactivating Proteins in Insects: HGT, gene expression, and functional implications. Gene 2023:147547. [PMID: 37286020 DOI: 10.1016/j.gene.2023.147547] [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: 03/22/2023] [Revised: 05/30/2023] [Accepted: 06/02/2023] [Indexed: 06/09/2023]
Abstract
Ribosome-inactivating proteins (RIPs) are RNA N-glycosidases that depurinate an adenine residue in the conserved alpha-sarcin/ricin loop (SRL) of rRNA, inhibiting protein synthesis. Previously, we reported the existence of these toxins in insects, whose presence is restricted to mosquitoes from the Culicinae subfamily (e.g., Aedes aegypti) and whiteflies from the Aleyrodidae family (e.g., Bemisia tabaci). Both groups of genes are derived from two independent horizontal gene transfer (HGT) events and are evolved under purifying selection. Here, we report and characterize the occurrence of a third HGT event in the Sciaroidea superfamily, which supports the recurrent acquisition of RIP genes by insects. Transcriptomic experiments, available in databases, allowed us to describe the temporal and spatial expression profiles for these foreign genes in these organisms. Furthermore, we found that RIP expression is induced after infection with pathogens and provided, for the first time, transcriptomic evidence of parasite SRL depurination. This evidence suggests a possible role of these foreign genes as immune effectors in insects.
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Affiliation(s)
- Walter J Lapadula
- Instituto Multidisciplinario de Investigaciones Biológicas de San Luis, IMIBIO-SL-CONICET and Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Ejército de Los Andes, 950, D5700HHW San Luis, Argentina.
| | - Maximiliano Juri Ayub
- Instituto Multidisciplinario de Investigaciones Biológicas de San Luis, IMIBIO-SL-CONICET and Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Ejército de Los Andes, 950, D5700HHW San Luis, Argentina
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Leucine 232 and hydrophobic residues at the ribosomal P stalk binding site are critical for biological activity of ricin. Biosci Rep 2020; 39:BSR20192022. [PMID: 31548364 PMCID: PMC6822507 DOI: 10.1042/bsr20192022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/15/2019] [Accepted: 08/21/2019] [Indexed: 01/16/2023] Open
Abstract
Ricin interacts with the ribosomal P stalk to cleave a conserved adenine from the α-sarcin/ricin loop (SRL) of the rRNA. Ricin toxin A chain (RTA) uses Arg235 as the most critical arginine for binding to the P stalk through electrostatic interactions to facilitate depurination. Structural analysis showed that a P2 peptide binds to a hydrophobic pocket on RTA and the last two residues form hydrogen bonds with Arg235. The importance of hydrophobic residues relative to Arg235 in the interaction with the P stalk in vivo and on the toxicity of RTA is not known. Here, we mutated residues in the hydrophobic pocket to analyze their contribution to toxicity and depurination activity in yeast and in mammalian cells. We found that Leu232, Tyr183 and Phe240 contribute cumulatively to toxicity, with Leu232 being the most significant. A quadruple mutant, Y183A/L232A/R235A/F240A, which combined mutations in critical hydrophobic residues with R235A completely abolished the activity of RTA, indicating that Arg235 and hydrophobic residues are required for full biological activity. Y183A and F240A mutants had reduced activity on RNA, but higher activity on ribosomes compared with R235A in vitro, suggesting that they could partially regain activity upon interaction with ribosomes. These results expand the region of interaction between RTA and the P stalk critical for cellular activity to include the hydrophobic pocket and provide the first evidence that interaction of P stalk with the hydrophobic pocket promotes a conformational rearrangement of RTA to correctly position the active site residues for catalytic attack on the SRL.
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Szajwaj M, Wawiórka L, Molestak E, Michalec-Wawiórka B, Mołoń M, Wojda I, Tchórzewski M. The influence of ricin-mediated rRNA depurination on the translational machinery in vivo - New insight into ricin toxicity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118554. [DOI: 10.1016/j.bbamcr.2019.118554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/10/2019] [Accepted: 09/04/2019] [Indexed: 11/29/2022]
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Pierce M, Vengsarkar D, McLaughlin JE, Kahn JN, Tumer NE. Ribosome depurination by ricin leads to inhibition of endoplasmic reticulum stress-induced HAC1 mRNA splicing on the ribosome. J Biol Chem 2019; 294:17848-17862. [PMID: 31624149 DOI: 10.1074/jbc.ra119.009128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 09/27/2019] [Indexed: 11/06/2022] Open
Abstract
Ricin undergoes retrograde transport to the endoplasmic reticulum (ER), and ricin toxin A chain (RTA) enters the cytosol from the ER. Previous reports indicated that RTA inhibits activation of the unfolded protein response (UPR) in yeast and in mammalian cells. Both precursor (preRTA) and mature form of RTA (mRTA) inhibited splicing of HAC1u (u for uninduced) mRNA, suggesting that UPR inhibition occurred on the cytosolic face of the ER. Here, we examined the role of ribosome binding and depurination activity on inhibition of the UPR using mRTA mutants. An active-site mutant with very low depurination activity, which bound ribosomes as WT RTA, did not inhibit HAC1u mRNA splicing. A ribosome-binding mutant, which showed reduced binding to ribosomes but retained depurination activity, inhibited HAC1u mRNA splicing. This mutant allowed separation of the UPR inhibition by RTA from cytotoxicity because it reduced the rate of depurination. The ribosome-binding mutant inhibited the UPR without affecting IRE1 oligomerization or cleavage of HAC1u mRNA at the splice site junctions. Inhibition of the UPR correlated with the depurination level, suggesting that ribosomes play a role in splicing of HAC1u mRNA. We show that HAC1u mRNA is associated with ribosomes and does not get processed on depurinated ribosomes, thereby inhibiting the UPR. These results demonstrate that RTA inhibits HAC1u mRNA splicing through its depurination activity on the ribosome without directly affecting IRE1 oligomerization or the splicing reaction and provide evidence that IRE1 recognizes HAC1u mRNA that is associated with ribosomes.
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Affiliation(s)
- Michael Pierce
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520
| | - Diana Vengsarkar
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520
| | - John E McLaughlin
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520
| | - Jennifer N Kahn
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520
| | - Nilgun E Tumer
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520
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Intracellular Transport and Cytotoxicity of the Protein Toxin Ricin. Toxins (Basel) 2019; 11:toxins11060350. [PMID: 31216687 PMCID: PMC6628406 DOI: 10.3390/toxins11060350] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 12/17/2022] Open
Abstract
Ricin can be isolated from the seeds of the castor bean plant (Ricinus communis). It belongs to the ribosome-inactivating protein (RIP) family of toxins classified as a bio-threat agent due to its high toxicity, stability and availability. Ricin is a typical A-B toxin consisting of a single enzymatic A subunit (RTA) and a binding B subunit (RTB) joined by a single disulfide bond. RTA possesses an RNA N-glycosidase activity; it cleaves ribosomal RNA leading to the inhibition of protein synthesis. However, the mechanism of ricin-mediated cell death is quite complex, as a growing number of studies demonstrate that the inhibition of protein synthesis is not always correlated with long term ricin toxicity. To exert its cytotoxic effect, ricin A-chain has to be transported to the cytosol of the host cell. This translocation is preceded by endocytic uptake of the toxin and retrograde traffic through the trans-Golgi network (TGN) and the endoplasmic reticulum (ER). In this article, we describe intracellular trafficking of ricin with particular emphasis on host cell factors that facilitate this transport and contribute to ricin cytotoxicity in mammalian and yeast cells. The current understanding of the mechanisms of ricin-mediated cell death is discussed as well. We also comment on recent reports presenting medical applications for ricin and progress associated with the development of vaccines against this toxin.
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How Ricin Damages the Ribosome. Toxins (Basel) 2019; 11:toxins11050241. [PMID: 31035546 PMCID: PMC6562825 DOI: 10.3390/toxins11050241] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Ricin belongs to the group of ribosome-inactivating proteins (RIPs), i.e., toxins that have evolved to provide particular species with an advantage over other competitors in nature. Ricin possesses RNA N-glycosidase activity enabling the toxin to eliminate a single adenine base from the sarcin-ricin RNA loop (SRL), which is a highly conserved structure present on the large ribosomal subunit in all species from the three domains of life. The SRL belongs to the GTPase associated center (GAC), i.e., a ribosomal element involved in conferring unidirectional trajectory for the translational apparatus at the expense of GTP hydrolysis by translational GTPases (trGTPases). The SRL represents a critical element in the GAC, being the main triggering factor of GTP hydrolysis by trGTPases. Enzymatic removal of a single adenine base at the tip of SRL by ricin blocks GTP hydrolysis and, at the same time, impedes functioning of the translational machinery. Here, we discuss the consequences of SRL depurination by ricin for ribosomal performance, with emphasis on the mechanistic model overview of the SRL modus operandi.
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Zhou Y, Li XP, Kahn JN, Tumer NE. Functional Assays for Measuring the Catalytic Activity of Ribosome Inactivating Proteins. Toxins (Basel) 2018; 10:toxins10060240. [PMID: 29899209 PMCID: PMC6024586 DOI: 10.3390/toxins10060240] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/01/2018] [Accepted: 06/07/2018] [Indexed: 12/11/2022] Open
Abstract
Ribosome-inactivating proteins (RIPs) are potent toxins that inactivate ribosomes by catalytically removing a specific adenine from the α-sarcin/ricin loop (SRL) of the large rRNA. Direct assays for measuring depurination activity and indirect assays for measuring the resulting translation inhibition have been employed to determine the enzyme activity of RIPs. Rapid and sensitive methods to measure the depurination activity of RIPs are critical for assessing their reaction mechanism, enzymatic properties, interaction with ribosomal proteins, ribotoxic stress signaling, in the search for inhibitors and in the detection and diagnosis of enteric infections. Here, we review the major assays developed for measuring the catalytic activity of RIPs, discuss their advantages and disadvantages and explain how they are used in understanding the catalytic mechanism, ribosome specificity, and dynamic enzymatic features of RIPs.
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Affiliation(s)
- Yijun Zhou
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
| | - Xiao-Ping Li
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
| | - Jennifer N Kahn
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
| | - Nilgun E Tumer
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
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Human ribosomal P1-P2 heterodimer represents an optimal docking site for ricin A chain with a prominent role for P1 C-terminus. Sci Rep 2017; 7:5608. [PMID: 28717148 PMCID: PMC5514047 DOI: 10.1038/s41598-017-05675-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 06/15/2017] [Indexed: 12/26/2022] Open
Abstract
The eukaryotic P-stalk contains two P1-P2 protein dimers with a conserved C- terminal domain (CTD) critical for the interaction with external factors. To understand the role of the individual CTD of human P1/P2 proteins, we examined the interaction of reconstituted human P-protein complexes and C-terminally truncated forms with ricin A chain (RTA), which binds to the stalk to depurinate the sarcin/ricin loop (SRL). The interaction between P-protein complexes and RTA was examined by surface plasmon resonance, isothermal titration calorimetry, microscale thermophoresis and bio-layer interferometry. The P1-P2 heterodimer missing a CTD on P2 was able to bind RTA. In contrast, the P1-P2 heterodimer missing the CTD of P1 protein displayed almost no binding toward RTA. Very low interaction was detected between RTA and the non-truncated P2-P2 homodimer, suggesting that the structural architecture of the P1-P2 heterodimer is critical for binding RTA. The reconstituted pentameric human stalk complex had higher affinity for RTA than the P1-P2 dimer. Deletion of P1 CTD, but not P2 CTD reduced the affinity of the pentamer for RTA. These results highlight the importance of the heterodimeric organization of P1-P2 in the human stalk pentamer and functional non-equivalence of the individual P-protein CTDs in the interaction with RTA.
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