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Nederlof RA, van der Veen D, Perrault JR, Bast R, Barron HW, Bakker J. Emerging Insights into Brevetoxicosis in Sea Turtles. Animals (Basel) 2024; 14:991. [PMID: 38612230 PMCID: PMC11010821 DOI: 10.3390/ani14070991] [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: 02/28/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
This review summarizes the current understanding of how brevetoxins, produced by Karenia brevis during harmful algal blooms, impact sea turtle health. Sea turtles may be exposed to brevetoxins through ingestion, inhalation, maternal transfer, and potentially absorption through the skin. Brevetoxins bind to voltage-gated sodium channels in the central nervous system, disrupting cellular function and inducing neurological symptoms in affected sea turtles. Moreover, the current evidence suggests a broader and longer-term impact on sea turtle health beyond what is seen during stranding events. Diagnosis relies on the detection of brevetoxins in tissues and plasma from stranded turtles. The current treatment of choice, intravenous lipid emulsion therapy, may rapidly reduce symptoms and brevetoxin concentrations, improving survival rates. Monitoring, prevention, and control strategies for harmful algal blooms are discussed. However, as the frequency and severity of blooms are expected to increase due to climate change and increased environmental pollution, continued research is needed to better understand the sublethal effects of brevetoxins on sea turtles and the impact on hatchlings, as well as the pharmacokinetic mechanisms underlying brevetoxicosis. Moreover, research into the optimization of treatments may help to protect endangered sea turtle populations in the face of this growing threat.
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Affiliation(s)
| | | | - Justin R. Perrault
- Loggerhead Marinelife Center, Juno Beach, FL 33408, USA; (J.R.P.); (H.W.B.)
| | - Robin Bast
- Clinic for the Rehabilitation of Wildlife, Inc., Sanibel, FL 33957, USA;
| | - Heather W. Barron
- Loggerhead Marinelife Center, Juno Beach, FL 33408, USA; (J.R.P.); (H.W.B.)
| | - Jaco Bakker
- Animal Science Department, Biomedical Primate Research Centre, Lange Kleiweg 161, 2288 GJ Rijswijk, The Netherlands;
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2
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Minns LA, Sausman KT, Brown AP, York RA, McCall JR. Karenia brevis Extract Induces Cellular Entry through Distinct Mechanisms in Phagocytic RAW 264.7 Macrophages versus Non-Phagocytic Vero Cells. Mar Drugs 2023; 22:4. [PMID: 38276642 PMCID: PMC10820030 DOI: 10.3390/md22010004] [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: 11/28/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 01/27/2024] Open
Abstract
Marine algae extracts are an important area of potential drug discovery; however, nearly all studies to date have used non-fluorescent-based methods to determine changes in target cell activity. Many of the most robust immunological and cellular analyses rely on fluorescent probes and readouts, which can be problematic when the algae extract is fluorescent itself. In this study, we identified the fluorescent spectrum of an isolated extract from the marine dinoflagellate Karenia brevis, which included two fluorescing components: chlorophyll α and pheophytin α. When excited at 405 nm and 664 nm, the extract emitted fluorescence at 676 nm and 696 nm, respectively. The extract and its fluorescing components, chlorophyll α and pheophytin α, entered phagocytic RAW 264.7 macrophages and non-phagocytic Vero kidney cells through distinct mechanisms. When incubated with the extract and its main components, both the RAW 264.7 macrophages and the Vero cells accumulated fluorescence as early as 30 min and continued through 48 h. Vero kidney cells accumulated the K. brevis fluorescent extract through a dynamin-independent and acidified endosomal-dependent mechanism. RAW 264.7 macrophages accumulated fluorescent extract through a dynamin-independent, acidified endosomal-independent mechanism, which supports accumulation through phagocytosis. Furthermore, RAW 264.7 macrophages downregulated cell-surface expression of CD206 in response to extract stimulation indicating activation of phagocytic responses and potential immunosuppression of these immune cells. This study represents the first characterization of the cellular update of K. brevis extracts in phagocytic versus non-phagocytic cells. The data suggest the importance of understanding cellular uptake of fluorescing algae extracts and their mechanism of action for future drug discovery efforts.
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Affiliation(s)
- Laurie A. Minns
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA; (L.A.M.)
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
| | - Kathryn T. Sausman
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA; (L.A.M.)
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
| | - Ariel P. Brown
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA; (L.A.M.)
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
| | - Robert A. York
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
- Algal Resources Collection, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
| | - Jennifer R. McCall
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA; (L.A.M.)
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K Moss Lane, Wilmington, NC 28409, USA
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Jobson J, Tsegay PS, Beltran MT, Taher EA, Rein SR, Liu Y, Rein KS. Brevetoxin induces a shift in the redox state of the proteome and unfolded protein response in human lymphoblast cells that can be alleviated with the acrolein scavenger MESNA. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023; 100:104137. [PMID: 37127110 DOI: 10.1016/j.etap.2023.104137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 04/24/2023] [Accepted: 04/29/2023] [Indexed: 05/03/2023]
Abstract
Human lymphoblast cells were treated with the marine algal toxin, brevetoxin-2 (PbTx-2), and its effects on the proteome were assessed by redox proteomics using cysteine reactive tandem mass tags (TMT). Additionally, cells were simultaneously treated with PbTx-2 and the antioxidant and acrolein scavenger sodium 2-mercaptoethylsulfonate (MESNA) to determine if MESNA could prevent the proteomic effects of brevetoxin-2. A massive shift in the redox state of the proteome of brevetoxin-2 treated cells was observed. The main pathway affected was genetic information processing. Significantly oxidized proteins included Trx-1, peroxyredoxins (Prxs), ribosomal proteins, and the eukaryotic initiation factor 2 β subunit (eIF2β). Proteins that were overexpressed in brevetoxin-treated cells included four folding chaperones. These effects were diminished in the presence of MESNA indicating that MESNA may act through its antioxidant properties or as a brevetoxin scavenger. These studies provide novel insights into new prophylactics for brevetoxicosis in humans and wildlife.
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Affiliation(s)
- Jordan Jobson
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Pawlos S Tsegay
- Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA
| | - Mayra Tabares Beltran
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Eman A Taher
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Samuel R Rein
- The School District of Philadelphia, Philadelphia, PA 19130, USA
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Current address: The Water School, Department of Marine and Earth Science and Department of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, FL 33965.
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Pesek JJ, Matyska MT, Hiltz T, McCall J. Application of a Cholesterol-Based Stationary Phase for the Analysis of Brevetoxins. J Sep Sci 2023; 46:e2200666. [PMID: 36369995 DOI: 10.1002/jssc.202200666] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/20/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022]
Abstract
A high-performance liquid chromatography protocol for the analysis of brevetoxins has been developed using a silica hydride-based cholesterol column. Brevetoxins are neurotoxins produced by harmful algae that have additional potential as drugs for a number of illnesses/diseases. To develop the optimum conditions, a number of different experimental approaches were tested. These include isocratic and gradient elution, different organic mobile phase components, and temperature variations. A separate protocol was developed for the compounds brevenal and brevenol, also produced by the same algae that make brevetoxins. Brevenal is a natural product under investigation as a therapy for chronic respiratory diseases, such as cystic fibrosis or asthma. The goal of this study was to provide a protocol for the analysis of these compounds that could be further developed into a validated method depending on a particular laboratory's capabilities and to highlight some of the unique features of the cholesterol stationary phase.
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Affiliation(s)
- Joseph J Pesek
- Department of Chemistry, San Jose State University, San Jose, California, USA
| | - Maria T Matyska
- Department of Chemistry, San Jose State University, San Jose, California, USA
| | - Tanya Hiltz
- MicroSolv Technology Corporation, Leland, North Carolina, USA
| | - Jennifer McCall
- University of North Carolina Wilmington, College of Health and Human Services, Wilmington, North Carolina, USA
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5
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Chen H, Wang J, Zhuang Y, Yu W, Liu G. Reduced Fitness and Elevated Oxidative Stress in the Marine Copepod Tigriopus japonicus Exposed to the Toxic Dinoflagellate Karenia mikimotoi. Antioxidants (Basel) 2022; 11:2299. [PMID: 36421485 PMCID: PMC9687495 DOI: 10.3390/antiox11112299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 11/13/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
Blooms of the toxic dinoflagellate Karenia mikimotoi cause devastation to marine life, including declines of fitness and population recruitment. However, little is known about the effects of them on benthic copepods. Here, we assessed the acute and chronic effects of K. mikimotoi on the marine benthic copepod Tigriopus japonicus. Results showed that adult females maintained high survival (>85%) throughout 14-d incubation, but time-dependent reduction of survival was detected in the highest K. mikimotoi concentration, and nauplii and copepodites were more vulnerable compared to adults. Ingestion of K. mikimotoi depressed the grazing of copepods but significantly induced the generation of reactive oxygen species (ROS), total antioxidant capacity, activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and acetylcholinesterase. Under sublethal concentrations for two generations, K. mikimotoi reduced the fitness of copepods by prolonging development time and decreasing successful development rate, egg production, and the number of clutches. Our findings suggest that the bloom of K. mikimotoi may threaten copepod population recruitment, and its adverse effects are associated with oxidative stress.
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Affiliation(s)
- Hongju Chen
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
- Laboratory for Marine Ecology and Environmental Science Laboratory, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Jing Wang
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Yunyun Zhuang
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
- Laboratory for Marine Ecology and Environmental Science Laboratory, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Wenzhuo Yu
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Guangxing Liu
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
- Laboratory for Marine Ecology and Environmental Science Laboratory, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
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6
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McCall JR, Sausman KT, Keeler DM, Brown AP, Turrise SL. Immune Modulating Brevetoxins: Monocyte Cytotoxicity, Apoptosis, and Activation of M1/M2 Response Elements Is Dependent on Reactive Groups. Mar Drugs 2022; 20:md20040233. [PMID: 35447906 PMCID: PMC9031394 DOI: 10.3390/md20040233] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/24/2022] [Accepted: 03/27/2022] [Indexed: 12/03/2022] Open
Abstract
Brevetoxins are a suite of marine neurotoxins that activate voltage-gated sodium channels (VGSCs) in cell membranes, with toxicity occurring from persistent activation of the channel at high doses. Lower doses, in contrast, have been shown to elicit neuroregeneration. Brevetoxins have thus been proposed as a novel treatment for patients after stroke, when neuron regrowth and repair is critical to recovery. However, findings from environmental exposures indicate that brevetoxins may cause inflammation, thus, there is concern for brevetoxins as a stroke therapy given the potential for neuroinflammation. In this study, we examined the inflammatory properties of several brevetoxin analogs, including those that do and do not bind strongly to VGSCs, as binding has classically indicated toxicity. We found that several analogs are toxic to monocytes, while others are not, and the degree of toxicity is not directly related to VGSC binding. Rather, results indicate that brevetoxins containing aldehyde groups were more likely to cause immunotoxicity, regardless of binding affinity to the VGSC. Our results demonstrate that different brevetoxin family members can elicit a spectrum of apoptosis and necrosis by multiple possible mechanisms of action in monocytes. As such, care should be taken in treating “brevetoxins” as a uniform group, particularly in stroke therapy research.
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Affiliation(s)
- Jennifer R. McCall
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, Wilmington, NC 28403, USA; (K.T.S.); (A.P.B.); (S.L.T.)
- Correspondence:
| | - Kathryn T. Sausman
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, Wilmington, NC 28403, USA; (K.T.S.); (A.P.B.); (S.L.T.)
| | | | - Ariel P. Brown
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, Wilmington, NC 28403, USA; (K.T.S.); (A.P.B.); (S.L.T.)
| | - Stephanie L. Turrise
- School of Nursing, College of Health and Human Services, University of North Carolina Wilmington, Wilmington, NC 28403, USA; (K.T.S.); (A.P.B.); (S.L.T.)
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7
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Zhang B, Fang J. Assay of selenol species in biological samples by the fluorescent probe Sel-green. Methods Enzymol 2022; 662:259-273. [PMID: 35101214 DOI: 10.1016/bs.mie.2021.10.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Selenium (Se) is an essential trace element for diverse cellular functions. The biological significance of Se is predominantly dependent on its incorporation into the selenocysteine (Sec) for synthesis of selenoproteins (SePs), such as thioredoxin reductase family enzymes and glutathione peroxidase family enzymes. In general, the hyperactivity of the selenol group in Sec confers the Sec residue critical for functions of SePs. The Sec is much less abundant than its sulfur analog cysteine (Cys), and it remains a high challenge to detect Sec, especially in complex biological samples. We recently reported a selective fluorescent probe Sel-green for selenols and summarized the principles for design of selenol (and thiophenol) probes. Sel-green discriminates selenols from other biological species, especially thiols, under physiological conditions, and has been applied to detect both endogenous and exogenous selenol species in live cells. In this chapter, we describe a protocol and guideline for the selective detection of Sec by applying the Sel-green. This protocol is also suitable for detection of other selenol species. This practical and convenient assay would assist scientists to better understand the pivotal roles of Sec as well as SePs.
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Affiliation(s)
- Baoxin Zhang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China
| | - Jianguo Fang
- State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China.
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8
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Colon R, Wheater M, Joyce EJ, Ste Marie EJ, Hondal RJ, Rein KS. The Marine Neurotoxin Brevetoxin (PbTx-2) Inhibits Karenia brevis and Mammalian Thioredoxin Reductases by Targeting Different Residues. JOURNAL OF NATURAL PRODUCTS 2021; 84:2961-2970. [PMID: 34752085 DOI: 10.1021/acs.jnatprod.1c00795] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The brevetoxins, neurotoxins produced by Karenia brevis, the Florida red tide dinoflagellate, effect fish and wildlife mortalities and adverse public health and economic impacts during recurrent blooms. Knowledge of the biochemical consequences of toxin production for K. brevis could provide insights into an endogenous role of the toxins, yet this aspect has not been thoroughly explored. In addition to neurotoxicity, the most abundant of the brevetoxins, PbTx-2, inhibits mammalian thioredoxin reductase (TrxR). The thioredoxin system, composed of the enzymes TrxR and thioredoxin (Trx), is present in all living organisms and is responsible in part for maintaining cellular redox homeostasis. Herein, we describe the cloning, expression, and semisynthesis of the selenoprotein TrxR from K. brevis (KbTrxR) and reductase activity toward a variety of substrates. Unlike mammalian TrxR, KbTrxR reduces oxidized glutathione (GSSG). We further demonstrate that PbTx-2 is an inhibitor of KbTrxR. Covalent adducts between KbTrxR and rat TrxR were detected by mass spectrometry. While both enzymes are adducted at or near the catalytic centers, the specific residues are distinct. Biochemical differences reported for high and low toxin producing strains of K. brevis are consistent with the inhibition of KbTrxR and suggest that PbTx-2 is an endogenous regulator of this critical enzyme.
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Affiliation(s)
- Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, Florida 33199, United States
| | - Michelle Wheater
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Emily J Joyce
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Emma J Ste Marie
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Robert J Hondal
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room 413B, Burlington, Vermont 05405, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, Florida 33199, United States
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Zhang J, Duan D, Osama A, Fang J. Natural Molecules Targeting Thioredoxin System and Their Therapeutic Potential. Antioxid Redox Signal 2021; 34:1083-1107. [PMID: 33115246 DOI: 10.1089/ars.2020.8213] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Significance: Thioredoxin (Trx) and thioredoxin reductase are two core members of the Trx system. The system bridges the gap between the universal reducing equivalent NADPH and various biological molecules and plays an essential role in maintaining cellular redox homeostasis and regulating multiple cellular redox signaling pathways. Recent Advance: In recent years, the Trx system has been well documented as an important regulator of many diseases, especially tumorigenesis. Thus, the development of potential therapeutic molecules targeting the system is of great significance for disease treatment. Critical Issues: We herein first discuss the physiological functions of the Trx system and the role that the Trx system plays in various diseases. Then, we focus on the introduction of natural small molecules with potential therapeutic applications, especially the anticancer activity, and review their mechanisms of pharmacological actions via interfering with the Trx system. Finally, we further discuss several natural molecules that harbor therapeutic potential and have entered different clinical trials. Future Directions: Further studies on the functions of the Trx system in multiple diseases will not only improve our understanding of the pathogenesis of many human disorders but also help develop novel therapeutic strategies against these diseases. Antioxid. Redox Signal. 34, 1083-1107.
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Affiliation(s)
- Junmin Zhang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, and School of Pharmacy, Lanzhou University, Lanzhou, China
- Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji, China
| | - Dongzhu Duan
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, and School of Pharmacy, Lanzhou University, Lanzhou, China
- Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji, China
| | - Alsiddig Osama
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, and School of Pharmacy, Lanzhou University, Lanzhou, China
- Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji, China
| | - Jianguo Fang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, and School of Pharmacy, Lanzhou University, Lanzhou, China
- Shaanxi Key Laboratory of Phytochemistry, Baoji University of Arts and Sciences, Baoji, China
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10
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Chupakhin E, Krasavin M. Thioredoxin reductase inhibitors: updated patent review (2017-present). Expert Opin Ther Pat 2021; 31:745-758. [PMID: 33666133 DOI: 10.1080/13543776.2021.1899160] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Introduction: Thioredoxin reductase (TrxR) is a selenocysteine-containing enzyme which is responsible - as a part of the thioredoxin system - for maintaining redox homeostasis in cells. It is upregulated in cancerous state as a defense against oxidative stress. TrxR has been mostly considered an anticancer drug target although it has applications in other therapeutic areas such as neurodegeneration, inflammation, microbial infections, and neonatal hyperoxic lung injury.Areas covered: The present review covers the patent literature that appeared in the period 2017-2020, i.e. since the publication of the previous expert opinion patent review on TrxR inhibitors. The recent additions to the following traditional classes of inhibitors are discussed: metal complexes, Michael acceptors as well as arsenic and selenium compounds. At the same time, a novel group of nitro (hetero)aromatic compounds have emerged which likely acts via covalent inhibition mechanism. Several miscellaneous chemotypes are grouped under Miscellaneous subsection.Expert opinion: While specificity over glutathione reductase is achieved easily, TrxR is still moving toward the later stages of development at a very slow rate. Michael acceptors, particularly based on TRXR substrate-mimicking scaffolds, are gaining impetus and so are dual and hybrid compounds. The development prospects of the emerging nitro (hetero)aromatic chemotypes remain uncertain.
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Affiliation(s)
- Evgeny Chupakhin
- Institute of Chemistry, Saint Petersburg State University, Saint Petersburg Russian Federation.,Institute for Living Systems, Immanuel Kant Baltic Federal University, Kaliningrad Russian Federation
| | - Mikhail Krasavin
- Institute of Chemistry, Saint Petersburg State University, Saint Petersburg Russian Federation.,Institute for Living Systems, Immanuel Kant Baltic Federal University, Kaliningrad Russian Federation
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11
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Colon R, Rein KS. Essential components of the xanthophyll cycle differ in high and low toxin Karenia brevis. HARMFUL ALGAE 2021; 103:102006. [PMID: 33980446 PMCID: PMC10246377 DOI: 10.1016/j.hal.2021.102006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/26/2021] [Accepted: 02/27/2021] [Indexed: 06/09/2023]
Abstract
The dinoflagellate Karenia brevis, blooms annually in the Gulf of Mexico, producing a suite of neurotoxins known as the brevetoxins. The cellular toxin content of K. brevis, however, is highly variable between or even within strains. Herein, we investigate physiological differences between high (KbHT) and low (KbLT) toxin producing cultures both derived from the Wilson strain, related to energy-dependent quenching (qE) by photosystem II, and reduced thiol content of the proteome. We demonstrate that gene and protein expression of the xanthophyll cycle enzyme diadinoxanthin de-epoxidase (Dde) and monogalactosyldiacylglycerol (MGDG) synthase are not significantly different in the two cultures. Using redox proteomics, we report a significantly higher reduced cysteine content in the low toxin proteome, including plastid localized thioredoxin reductase (Trx) which can result in inactivation of Dde and activation of MGDG synthase. We also report significant differences in the lipidomes of KbHT and KbLT with respect to MGDG, which facilitates the xanthophyll cycle.
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Affiliation(s)
- Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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12
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Zhang W, Zhu Y, Yu H, Liu X, Jiao B, Lu X. Libertellenone H, a Natural Pimarane Diterpenoid, Inhibits Thioredoxin System and Induces ROS-Mediated Apoptosis in Human Pancreatic Cancer Cells. Molecules 2021; 26:molecules26020315. [PMID: 33435380 PMCID: PMC7827531 DOI: 10.3390/molecules26020315] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/28/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
Libertellenone H (LH), a marine-derived pimarane diterpenoid isolated from arctic fungus Eutypella sp. D-1, has shown effective cytotoxicity on a range of cancer cells. The present study is to explore the anticancer effect of LH on human pancreatic cancer cells and to investigate the intracellular molecular target and underlying mechanism. As shown, LH exhibited anticancer activity in human pancreatic cancer cells by promoting cell apoptosis. Mechanistic studies suggested that LH-induced reactive oxygen species (ROS) accumulation was responsible for apoptosis as antioxidant N-acetylcysteine (NAC) and antioxidant enzyme superoxide dismutase (SOD) antagonized the inhibitory effect of LH. Zymologic testing demonstrated that LH inhibited Trx system but had little effect on the glutathione reductase and glutaredoxin. Mass spectrometry (MS) analysis revealed that the mechanism of action was based on the direct conjugation of LH to the Cys32/Cys35 residue of Trx1 and Sec498 of TrxR, leading to a decrease in the cellular level of glutathione (GSH) and activation of downstream ASK1/JNK signaling pathway. Taken together, our findings revealed LH was a marine derived inhibitor of Trx system and an anticancer candidate.
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Affiliation(s)
- Weirui Zhang
- College of Basic Medical Sciences, Department of Biochemistry and Molecular Biology, Naval Medical University, Shanghai 200433, China; (W.Z.); (H.Y.); (X.L.)
| | - Yuping Zhu
- College of Basic Medical Sciences, Experimental Teacher Center, Naval Medical University, Shanghai 200433, China;
| | - Haobing Yu
- College of Basic Medical Sciences, Department of Biochemistry and Molecular Biology, Naval Medical University, Shanghai 200433, China; (W.Z.); (H.Y.); (X.L.)
| | - Xiaoyu Liu
- College of Basic Medical Sciences, Department of Biochemistry and Molecular Biology, Naval Medical University, Shanghai 200433, China; (W.Z.); (H.Y.); (X.L.)
| | - Binghua Jiao
- College of Basic Medical Sciences, Department of Biochemistry and Molecular Biology, Naval Medical University, Shanghai 200433, China; (W.Z.); (H.Y.); (X.L.)
- Correspondence: (B.J.); (X.L.); Tel.: +86-21-81870970 (ext. 8001) (B.J.); +86-21-81870970 (ext. 8004) (X.L.)
| | - Xiaoling Lu
- College of Basic Medical Sciences, Department of Biochemistry and Molecular Biology, Naval Medical University, Shanghai 200433, China; (W.Z.); (H.Y.); (X.L.)
- Correspondence: (B.J.); (X.L.); Tel.: +86-21-81870970 (ext. 8001) (B.J.); +86-21-81870970 (ext. 8004) (X.L.)
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13
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Walsh CJ, Cocilova C, Restivo J, Flewelling L, Milton S. Immune function in Trachemys scripta following exposure to a predominant brevetoxin congener, PbTx-3, as a model for potential health impacts for sea turtles naturally exposed to brevetoxins. ECOTOXICOLOGY (LONDON, ENGLAND) 2019; 28:1085-1104. [PMID: 31559558 DOI: 10.1007/s10646-019-02110-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/09/2019] [Indexed: 06/10/2023]
Abstract
Many species of marine life in southwestern Florida, including sea turtles, are impacted by blooms of the toxic dinoflagellate, Karenia brevis. Sublethal exposure to toxins produced by K. brevis has been shown to impact sea turtle health. Since all sea turtles in the Gulf of Mexico have protected status, a freshwater turtle, Trachemys scripta, was used as a model for immune system effects following experimental exposure to a predominant brevetoxin congener in K. brevis blooms, PbTx-3. Exposure to PbTx-3 was oral or intratracheal and health effects were assessed using a suite of immune function parameters: innate immune function (phagocytosis, plasma lysozyme activity), adaptive immune function (lymphocyte proliferation), and measures of oxidative stress (superoxide dismutase (SOD) and glutathione-S-transferase (GST) activity in plasma). Inflammation was also measured using plasma protein electrophoresis. In addition, differential expression of genes in peripheral blood leukocytes was determined using suppression subtractive hybridization followed by real-time PCR of specific genes. The primary immune effects of sublethal brevetoxin exposure in T. scripta following PbTx-3 administration, appear to be an increase in oxidative stress, a decrease in lysozyme activity, and modulation of immune function through lymphocyte proliferation responses. Plasma protein electrophoresis showed a decreased A:G ratio which may indicate potential inflammation. Genes coding for oxidative stress, such as thioredoxin and GST, were upregulated in exposed animals. That sublethal brevetoxin exposures impact immune function components suggests potential health implications for sea turtles naturally exposed to toxins. Knowledge of physiological stressors induced by brevetoxins may contribute to the ultimate goal of developing directed treatment strategies in exposed animals for reduced mortality resulting from red tide toxin exposure in sea turtles.
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Affiliation(s)
- Catherine J Walsh
- Marine Immunology Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA.
| | - Courtney Cocilova
- Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
| | - Jessica Restivo
- Marine Immunology Program, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
| | - Leanne Flewelling
- Florida Fish and Wildlife Conservation Commission, 100 8th Ave SE, St. Petersburg, FL, 33701, USA
| | - Sarah Milton
- Florida Atlantic University, 777 Glades Road, Boca Raton, FL, 33431, USA
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14
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Liao J, Wang L, Wu Z, Wang Z, Chen J, Zhong Y, Jiang F, Lu Y. Identification of phenazine analogue as a novel scaffold for thioredoxin reductase I inhibitors against Hep G2 cancer cell lines. J Enzyme Inhib Med Chem 2019; 34:1158-1163. [PMID: 31179772 PMCID: PMC6567043 DOI: 10.1080/14756366.2019.1624541] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Even though phenazines have been extensively reported as anticancer molecules, the molecular target of these compounds is severely lagging behind. Our study consequently focuses on the anticancer target of a phenazine analogue (CPUL1) for its potently antitumor activities in initial stage. Along with redox status courses of Hep G2 cells, thioredoxin reductase I (TrxR1) was speculated as anticancer target of CPUL1. By virtue of zymologic, immunological and molecular biological experiments, we demonstrated that TrxR1 could be the anticancer target of CPUL1. The knowledge on phenazine targeting to TrxR1 have not been reported previously. Thus, it can provide valuable information for further development of the TrxR1 inhibitors.
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Affiliation(s)
- Jianming Liao
- a School of Life Science and Technology , China Pharmaceutical University , Nanjing , China
| | - Linlin Wang
- a School of Life Science and Technology , China Pharmaceutical University , Nanjing , China
| | - Zhongxi Wu
- b School of Engineering , China Pharmaceutical University , Nanjing , China
| | - Zhixiang Wang
- b School of Engineering , China Pharmaceutical University , Nanjing , China
| | - Jun Chen
- a School of Life Science and Technology , China Pharmaceutical University , Nanjing , China
| | - Yucheng Zhong
- a School of Life Science and Technology , China Pharmaceutical University , Nanjing , China
| | - Feng Jiang
- b School of Engineering , China Pharmaceutical University , Nanjing , China
| | - Yuanyuan Lu
- a School of Life Science and Technology , China Pharmaceutical University , Nanjing , China
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15
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Tuladhar A, Hondal RJ, Colon R, Hernandez EL, Rein KS. Effectors of thioredoxin reductase: Brevetoxins and manumycin-A. Comp Biochem Physiol C Toxicol Pharmacol 2019; 217:76-86. [PMID: 30476593 PMCID: PMC7485175 DOI: 10.1016/j.cbpc.2018.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 02/03/2023]
Abstract
The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme. In general, the reduction of substrates by Sec-containing TrxR is inhibited and NADPH oxidase activity is activated. For non-Sec-containing TrxR the effect of Man-A on the reduction of substrates is variable, but NADPH oxidase activity can be activated even in the absence of covalent modification of TrxR. The effect of PbTx is less pronounced. A smaller subset of enzymes is affected by PbTx. With a single exception, the activities of most of this subset are activated. Although both PbTx variants can react with selenocysteine, a stable covalent adduct is not formed with any of the TrxR enzymes. The key findings from this work are (i) the identification of an alternate mechanism of toxicity for the algal toxin brevetoxin (ii) the demonstration that covalent modification of TrxR is not a prerequisite for the activation of NADPH oxidase activity of TrxR and (iii) the identification of an inhibitor which can discriminate between cytosolic and mitochondrial TrxR.
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Robert J Hondal
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room 413B, Burlington, VT 05405, United States
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Elyssa L Hernandez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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16
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Tuladhar A, Rein KS. Manumycin A Is a Potent Inhibitor of Mammalian Thioredoxin Reductase-1 (TrxR-1). ACS Med Chem Lett 2018; 9:318-322. [PMID: 29670693 DOI: 10.1021/acsmedchemlett.7b00489] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/05/2018] [Indexed: 12/15/2022] Open
Abstract
The anticancer effect of manumycin A (Man A) has been attributed to the inhibition of farnesyl transferase (FTase), an enzyme that is responsible for post-translational modification of Ras proteins. However, we have discovered that Man A inhibits mammalian cytosolic thioredoxin reductase 1 (TrxR-1) in a time-dependent manner, with an IC50 of 272 nM with preincubation and 1586 nM without preincubation. The inhibition of TrxR-1 by Man A is irreversible and is the result of a covalent interaction between Man A and TrxR-1. Evidence presented herein demonstrates that Man A forms a Michael adduct with the selenocysteine residue, which is located in the C-terminal redox center of TrxR-1. Inhibitors of TrxR-1, which act through this mechanism, convert TrxR-1 into a SecTRAP, which utilizes NADPH to reduce oxygen to superoxide radical anion (O2-•).
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, Florida 33199, United States
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, Florida 33199, United States
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17
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Chen W, Colon R, Louda JW, Del Rey FR, Durham M, Rein KS. Brevetoxin (PbTx-2) influences the redox status and NPQ of Karenia brevis by way of thioredoxin reductase. HARMFUL ALGAE 2018; 71:29-39. [PMID: 29306394 PMCID: PMC5994908 DOI: 10.1016/j.hal.2017.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 11/18/2017] [Accepted: 11/18/2017] [Indexed: 06/07/2023]
Abstract
The Florida red tide dinoflagellate, Karenia brevis, is the major harmful algal bloom dinoflagellate of the Gulf of Mexico and plays a destructive role in the region. Blooms of K. brevis can produce brevetoxins: ladder-shaped polyether (LSP) compounds, which can lead to adverse human health effects, such as reduced respiratory function through inhalation exposure, or neurotoxic shellfish poisoning through consumption of contaminated shellfish. The endogenous role of the brevetoxins remains uncertain. Recent work has shown that some forms of NADPH dependent thioredoxin reductase (NTR) are inhibited by brevetoxin-2 (PbTx-2). The study presented herein reveals that high toxin and low toxin K. brevis, which have a ten-fold difference in toxin content, also show a significant difference in their ability, not only to produce brevetoxin, but also in their cellular redox status and distribution of xanthophyll cycle pigments. These differences are likely due to the inhibition of NTR by brevetoxin. The work could shed light on the physiological role that brevetoxin fills for K. brevis.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - J William Louda
- Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 United States.
| | - Freddy Rodriguez Del Rey
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Michaella Durham
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8thStreet, Miami, FL 33199, United States.
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