Toxins

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Open AccessReview

Ribosome-Inactivating Proteins: From Plant Defense to Tumor Attack

by Maddalena de Virgilio, Alessio Lombardi, Rocco Caliandro and Maria Serena Fabbrini

Toxins 2010, 2(11), 2699-2737; https://doi.org/10.3390/toxins2112699 - 10 Nov 2010

Cited by 130 | Viewed by 16435

Ribosome-inactivating proteins (RIPs) are EC3.2.32.22 N-glycosidases that recognize a universally conserved stem-loop structure in 23S/25S/28S rRNA, depurinating a single adenine (A4324 in rat) and irreversibly blocking protein translation, leading finally to cell death of intoxicated mammalian cells. Ricin, the plant RIP prototype that [...] Read more.

Ribosome-inactivating proteins (RIPs) are EC3.2.32.22 N-glycosidases that recognize a universally conserved stem-loop structure in 23S/25S/28S rRNA, depurinating a single adenine (A4324 in rat) and irreversibly blocking protein translation, leading finally to cell death of intoxicated mammalian cells. Ricin, the plant RIP prototype that comprises a catalytic A subunit linked to a galactose-binding lectin B subunit to allow cell surface binding and toxin entry in most mammalian cells, shows a potency in the picomolar range. The most promising way to exploit plant RIPs as weapons against cancer cells is either by designing molecules in which the toxic domains are linked to selective tumor targeting domains or directly delivered as suicide genes for cancer gene therapy. Here, we will provide a comprehensive picture of plant RIPs and discuss successful designs and features of chimeric molecules having therapeutic potential. Full article

(This article belongs to the Special Issue Toxins as Therapeutics)

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625 KiB

Open AccessReview

Genetics of Dothistromin Biosynthesis of Dothistroma septosporum: An Update

by Arne Schwelm and Rosie E. Bradshaw

Toxins 2010, 2(11), 2680-2698; https://doi.org/10.3390/toxins2112680 - 5 Nov 2010

Cited by 21 | Viewed by 10302

Abstract

Dothistroma needle blight is one of the most devastating fungal pine diseases worldwide. The disease is characterized by accumulation in pine needles of a red toxin, dothistromin, that is chemically related to aflatoxin (AF) and sterigmatocystin (ST). This review updates current knowledge of [...] Read more.

Dothistroma needle blight is one of the most devastating fungal pine diseases worldwide. The disease is characterized by accumulation in pine needles of a red toxin, dothistromin, that is chemically related to aflatoxin (AF) and sterigmatocystin (ST). This review updates current knowledge of the genetics of dothistromin biosynthesis by the Dothistroma septosporum pathogen and highlights differences in gene organization and regulation that have been discovered between the dothistromin and AF/ST systems. Some previously reported genes are promoted or demoted as ‘dothistromin genes’ based on recent research. A new dothistromin gene, norB, is reported, and evidence of dothistromin gene homologs in other Dothideomycete fungi is presented. A hypothesis for the biological role of dothistromin is outlined. Finally, the impact that the availability of the D. septosporum genome sequence will have on dothistromin research is discussed. Full article

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Open AccessArticle

β-N-Methylamino-L-Alanine Induces Neurological Deficits and Shortened Life Span in Drosophila

by Xianchong Zhou, Wilfredo Escala, Spyridon Papapetropoulos and R. Grace Zhai

Toxins 2010, 2(11), 2663-2679; https://doi.org/10.3390/toxins2112663 - 3 Nov 2010

Cited by 23 | Viewed by 10094

Abstract

The neurotoxic non-protein amino acid, β-N-methylamino-L-alanine (BMAA), was first associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam. Recently, BMAA has been implicated as a fierce environmental factor that contributes to the etiology of Alzheimer’s and Parkinson’s diseases, [...] Read more.

The neurotoxic non-protein amino acid, β-N-methylamino-L-alanine (BMAA), was first associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam. Recently, BMAA has been implicated as a fierce environmental factor that contributes to the etiology of Alzheimer’s and Parkinson’s diseases, in addition to ALS. However, the toxicity of BMAA in vivo has not been clearly demonstrated. Here we report our investigation of the neurotoxicity of BMAA in Drosophila. We found that dietary intake of BMAA reduced life span, locomotor functions, and learning and memory abilities in flies. The severity of the alterations in phenotype is correlated with the concentration of BMAA detected in flies. Interestingly, developmental exposure to BMAA had limited impact on survival rate, but reduced fertility in females, and caused delayed neurological impairment in aged adults. Our studies indicate that BMAA exposure causes chronic neurotoxicity, and that Drosophila serves as a useful model in dissecting the pathogenesis of ALS/PDC. Full article

(This article belongs to the Special Issue Neurotoxins of Biological Origin)

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155 KiB

Open AccessReview

Targeted Toxins in Brain Tumor Therapy

by Yan Michael Li and Walter A. Hall

Toxins 2010, 2(11), 2645-2662; https://doi.org/10.3390/toxins2112645 - 1 Nov 2010

Cited by 37 | Viewed by 8960

Abstract

Targeted toxins, also known as immunotoxins or cytotoxins, are recombinant molecules that specifically bind to cell surface receptors that are overexpressed in cancer and the toxin component kills the cell. These recombinant proteins consist of a specific antibody or ligand coupled to a [...] Read more.

Targeted toxins, also known as immunotoxins or cytotoxins, are recombinant molecules that specifically bind to cell surface receptors that are overexpressed in cancer and the toxin component kills the cell. These recombinant proteins consist of a specific antibody or ligand coupled to a protein toxin. The targeted toxins bind to a surface antigen or receptor overexpressed in tumors, such as the epidermal growth factor receptor or interleukin-13 receptor. The toxin part of the molecule in all clinically used toxins is modified from bacterial or plant toxins, fused to an antibody or carrier ligand. Targeted toxins are very effective against cancer cells resistant to radiation and chemotherapy. They are far more potent than any known chemotherapy drug. Targeted toxins have shown an acceptable profile of toxicity and safety in early clinical studies and have demonstrated evidence of a tumor response. Currently, clinical trials with some targeted toxins are complete and the final results are pending. This review summarizes the characteristics of targeted toxins and the key findings of the important clinical studies with targeted toxins in malignant brain tumor patients. Obstacles to successful treatment of malignant brain tumors include poor penetration into tumor masses, the immune response to the toxin component and cancer heterogeneity. Strategies to overcome these limitations are being pursued in the current generation of targeted toxins. Full article

(This article belongs to the Special Issue Toxins as Therapeutics)

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Open AccessReview

Tetanus Toxin C-Fragment: The Courier and the Cure?

by Janne M. Toivonen, Sara Oliván and Rosario Osta

Toxins 2010, 2(11), 2622-2644; https://doi.org/10.3390/toxins2112622 - 29 Oct 2010

Cited by 46 | Viewed by 11579

Abstract

In many neurological disorders strategies for a specific delivery of a biological activity from the periphery to the central nervous system (CNS) remains a considerable challenge for successful therapy. Reporter assays have established that the non-toxic C‑fragment of tetanus toxin (TTC), provided either [...] Read more.

In many neurological disorders strategies for a specific delivery of a biological activity from the periphery to the central nervous system (CNS) remains a considerable challenge for successful therapy. Reporter assays have established that the non-toxic C‑fragment of tetanus toxin (TTC), provided either as protein or encoded by non-viral naked DNA plasmid, binds pre-synaptic motor neuron terminals and can facilitate the retrograde axonal transport of desired therapeutic molecules to the CNS. Alleviated symptoms in animal models of neurological diseases upon delivery of therapeutic molecules offer a hopeful prospect for TTC therapy. This review focuses on what has been learned on TTC-mediated neuronal targeting, and discusses the recent discovery that, instead of being merely a carrier molecule, TTC itself may well harbor neuroprotective properties. Full article

(This article belongs to the Special Issue Toxins as Therapeutics)

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Open AccessReview

Snake Venom Disintegrins and Cell Migration

by Heloisa S. Selistre-de-Araujo, Carmen L. S. Pontes, Cyntia F. Montenegro and Ana Carolina B. M. Martin

Toxins 2010, 2(11), 2606-2621; https://doi.org/10.3390/toxins2112606 - 29 Oct 2010

Cited by 62 | Viewed by 11100

Abstract

Cell migration is a key process for the defense of pluricellular organisms against pathogens, and it involves a set of surface receptors acting in an ordered fashion to contribute directionality to the movement. Among these receptors are the integrins, which connect the cell [...] Read more.

Cell migration is a key process for the defense of pluricellular organisms against pathogens, and it involves a set of surface receptors acting in an ordered fashion to contribute directionality to the movement. Among these receptors are the integrins, which connect the cell cytoskeleton to the extracellular matrix components, thus playing a central role in cell migration. Integrin clustering at focal adhesions drives actin polymerization along the cell leading edge, resulting in polarity of cell movement. Therefore, small integrin-binding proteins such as the snake venom disintegrins that inhibit integrin-mediated cell adhesion are expected to inhibit cell migration. Here we review the current knowledge on disintegrin and disintegrin-like protein effects on cell migration and their potential use as pharmacological tools in anti-inflammatory therapy as well as in inhibition of metastatic invasion. Full article

(This article belongs to the Special Issue Disintegrins: Structure-Function and Translational Potential)

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Open AccessReview

Ecophysiology of Aspergillus Section Nigri Species Potential Ochratoxin A Producers

by Andrea L. Astoreca, Carina E. Magnoli and Ana M. Dalcero

Toxins 2010, 2(11), 2593-2605; https://doi.org/10.3390/toxins2112593 - 29 Oct 2010

Cited by 28 | Viewed by 8975

Abstract

After aflatoxins, ochratoxin A (OTA) is the most studied mycotoxin due to the toxicological significance in human and animal diets. OTA presence has been extensively reported worldwide in the last decade in several agricultural products. The main OTA producer in tropical and temperate [...] Read more.

After aflatoxins, ochratoxin A (OTA) is the most studied mycotoxin due to the toxicological significance in human and animal diets. OTA presence has been extensively reported worldwide in the last decade in several agricultural products. The main OTA producer in tropical and temperate climates is Aspergillus carbonarius followed by species belonging to A. niger aggregate. Currently, many scientists worldwide have studied the influence of water activity and temperature for growth and biosynthesis of OTA by these species on synthetic media. This article reviews ecophysiological studies of Aspergillus section Nigri strains on synthetic media and natural substrates. The results of these investigations suggest that significant amounts of OTA can be produced in only five days and that the use of different storage practices, such as a_W and temperature levels below 0.930 and 15 °C, respectively, allow controlling fungal contamination and minimizing the OTA production in several products as peanuts, corn, dried grapes and derived products for human consumption. Full article

(This article belongs to the Special Issue Ochratoxins)

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Open AccessArticle

Warfarin Toxicity and Individual Variability—Clinical Case

by Irina Piatkov, Colin Rochester, Trudi Jones and Steven Boyages

Toxins 2010, 2(11), 2584-2592; https://doi.org/10.3390/toxins2112584 - 28 Oct 2010

Cited by 19 | Viewed by 17698

Abstract

Warfarin is a widely used anticoagulant in the treatment and prevention of thrombosis, in the treatment for chronic atrial fibrillation, mechanical valves, pulmonary embolism, and dilated cardiomyopathy. It is tasteless and colorless, was used as a poison, and is still marketed as a [...] Read more.

Warfarin is a widely used anticoagulant in the treatment and prevention of thrombosis, in the treatment for chronic atrial fibrillation, mechanical valves, pulmonary embolism, and dilated cardiomyopathy. It is tasteless and colorless, was used as a poison, and is still marketed as a pesticide against rats and mice. Several long-acting warfarin derivatives—superwarfarin anticoagulants—such as brodifacoum, diphenadione, chlorophacinone, bromadiolone, are used as pesticides and can produce profound and prolonged anticoagulation. Several factors increase the risk of warfarin toxicity. However, polymorphisms in cytochrome P450 genes and drug interactions account for most of the risk for toxicity complications. Each person is unique in their degree of susceptibility to toxic agents. The toxicity interpretation and the health risk of most toxic substances are a subject of uncertainty. Genetically determined low metabolic capacity in an individual can dramatically alter the toxin and metabolite levels from those normally expected, which is crucial for drugs with a narrow therapeutic index, like warfarin. Personalized approaches in interpretation have the potential to remove some of the scientific uncertainties in toxicity cases. Full article

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Open AccessReview

Toxin-Based Therapeutic Approaches

by Assaf Shapira and Itai Benhar

Toxins 2010, 2(11), 2519-2583; https://doi.org/10.3390/toxins2112519 - 28 Oct 2010

Cited by 119 | Viewed by 22185

Abstract

Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying [...] Read more.

Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin. Full article

(This article belongs to the Special Issue Toxins as Therapeutics)

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657 KiB

Open AccessReview

Mechanisms of Cisplatin Nephrotoxicity

by Ronald P. Miller, Raghu K. Tadagavadi, Ganesan Ramesh and William Brian Reeves

Toxins 2010, 2(11), 2490-2518; https://doi.org/10.3390/toxins2112490 - 26 Oct 2010

Cited by 1308 | Viewed by 45051

Abstract

Cisplatin is a widely used and highly effective cancer chemotherapeutic agent. One of the limiting side effects of cisplatin use is nephrotoxicity. Research over the past 10 years has uncovered many of the cellular mechanisms which underlie cisplatin-induced renal cell death. It has [...] Read more.

Cisplatin is a widely used and highly effective cancer chemotherapeutic agent. One of the limiting side effects of cisplatin use is nephrotoxicity. Research over the past 10 years has uncovered many of the cellular mechanisms which underlie cisplatin-induced renal cell death. It has also become apparent that inflammation provoked by injury to renal epithelial cells serves to amplify kidney injury and dysfunction in vivo. This review summarizes recent advances in our understanding of cisplatin nephrotoxicity and discusses how these advances might lead to more effective prevention. Full article

(This article belongs to the Special Issue Renal Toxicity)

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Toxins, Volume 2, Issue 11 (November 2010) – 10 articles , Pages 2490-2737

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