Marine toxins and the cytoskeleton: azaspiracids

Vilariño, Natalia

doi:10.1111/j.1742-4658.2008.06713.x

Cited by 34 publications

(24 citation statements)

References 39 publications

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“…This effect is consistent with the in vivo effects inducing complete degradation of gastrointestinal lining and confirmed by TEER experiments on monolayer Caco2 model [30] or by disturbance of filament organization in Caco2 cells [31]. Even if some data indicated that AZA1 induced the fragmentation of E-cadherin [21] and inhibited endocytosis [32], its molecular target is still unknown.…”

Section: Dose-response Relationship and Ic 50 Valuessupporting

confidence: 89%

“…The human HepG2 hepatocarcinoma cell line (ATCC HB8065, passages [15][16][17][18][19][20][21][22][23][24][25] and the human Caco2 colorectal adenocarcinoma cell line (ATCC HTB-37, passages were cultured in MEM-Glutamax containing 1 g/l glucose and supplemented with 10 % fetal calf serum (FCS), 50 U/mL penicillin and 50 μg/mL streptomycin, and 1 % nonessential amino acids. The mouse Neuro2a neuroblastoma cell line (ATCC CCL-131, passages 11-50) was cultured in RPMI 1640-Glutamax containing 2 g/l glucose and supplemented with 10 % FCS, 1 mM sodium pyruvate, 50 U/mL penicillin, and 50 μg/mL streptomycin.…”

Section: Cell Maintenancementioning

confidence: 99%

“…To date, the cellular effects of phycotoxins have been studied on a range of cell types including neuroblastoma [7][8][9][10][11][12][13][14], fibroblasts [15,16], myoblasts [17], and intestinal cells [18]. Some studies have been designed to characterize the toxic effect of one toxin on different cell types, like for AZA1 cytotoxicity [19][20][21]. The effects of pectenotoxins (PTXs) on the actin skeleton were first evidenced by Hori et al [18].…”

Section: Introductionmentioning

confidence: 97%

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Collaborative study for the detection of toxic compounds in shellfish extracts using cell-based assays. Part I: screening strategy and pre-validation study with lipophilic marine toxins

et al. 2012

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Human poisoning due to consumption of seafood contaminated with phycotoxins is a worldwide problem, and routine monitoring programs have been implemented in various countries to protect human consumers. Following successive episodes of unexplained shellfish toxicity since 2005 in the Arcachon Bay on the French Atlantic coast, a national research program was set up to investigate these atypical toxic events. Part of this program was devoted to fit-for-purpose cell-based assays (CBA) as complementary tools to collect toxicity data on atypical positive-mouse bioassay shellfish extracts. A collaborative study involving five laboratories was conducted. The responses of human hepatic (HepG2), human intestinal (Caco2), and mouse neuronal (Neuro2a) cell lines exposed to three known lipophilic phycotoxins-okadaic acid (OA), azaspiracid-1 (AZA1), and pectenotoxin-2 (PTX2)-were investigated. A screening strategy composed of standard operating procedures and a decision tree for dose-response modeling and assay validation were designed after a round of "trial-and-error" process. For each toxin, the shape of the concentration-response curves and the IC(50) values were determined on the three cell lines. Whereas OA induced a similar response irrespective of the cell line (complete sigmoid), PTX2 was shown to be less toxic. AZA1 induced cytotoxicity only on HepG2 and Neuro2a, but not on Caco2. Intra- and inter-laboratory coefficients of variation of cell responses were large, with mean values ranging from 35 to 54 % and from 37 to 48 %, respectively. Investigating the responses of the selected cell lines to well-known toxins is the first step supporting the use of CBA among the panel of methods for characterizing atypical shellfish toxicity. Considering these successful results, the CBA strategy will be further applied to extracts of negative, spiked, and naturally contaminated shellfish tissues.

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Section: Dose-response Relationship and Ic 50 Valuessupporting

confidence: 89%

Section: Cell Maintenancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Collaborative study for the detection of toxic compounds in shellfish extracts using cell-based assays. Part I: screening strategy and pre-validation study with lipophilic marine toxins

et al. 2012

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“…8 In vivo studies in mice exposed to AZA1 revealed severe effects such as deformation of intestinal epithelial villi 9, 10 as well as damage to T and B lymphocytes, accumulation of fatty acid deposits in the liver, increased prevalence of lung tumors, and hyperplasia within the stomach lining. 11, 12 In vitro studies have shown the AZAs to be highly cytotoxic causing a variety of cytoskeletal effects 13-18 and stimulation of cAMP production and cytosolic calcium release. 19, 20 In spinal cord neurons, AZA1 was shown to inhibit bioelectrical activity through a mechanism that was independent of voltage-gated sodium (Na + ) or calcium (Ca 2+ ) current.…”

Section: Introductionmentioning

confidence: 99%

Marine Algal Toxin Azaspiracid Is an Open-State Blocker of hERG Potassium Channels

Twiner

Doucette

Rasky

et al. 2012

Chem. Res. Toxicol.

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Azaspiracids (AZA) are polyether marine dinoflagellate toxins that accumulate in shellfish and represent an emerging human health risk. Although human exposure is primarily manifested by severe and protracted diarrhea, this toxin class has been shown to be highly cytotoxic, a teratogen to developing fish, and a possible carcinogen in mice. Until now, AZA's molecular target(s) has not yet been determined. Using three independent methods (voltage clamp, channel binding assay, and thallium flux assay), we have for the first time demonstrated that AZA1, AZA2, and AZA3 each bind to and block the hERG (human ether-à-go-go related gene) potassium channel heterologously expressed in HEK-293 mammalian cells. Inhibition of K+ current for each AZA analogue was concentration-dependent (IC50 value range: 0.64 - 0.84 μM). The mechanism of hERG channel inhibition by AZA1 was investigated further in Xenopus oocytes where it was shown to be an open state-dependent blocker and, using mutant channels, to interact with F656 but not with Y652 within the S6 transmembrane domain that forms the channel's central pore. AZA1, AZA2, and AZA3 were each shown to inhibit [3H]dofetilide binding to the hERG channel and thallium ion flux through the channel (IC50 value range: 2.1 – 6.6 μM). AZA1 did not block K+ current of the closely related EAG1 channel. Collectively, these data suggest that the AZAs physically block the K+ conductance pathway of hERG1 channels by occluding the cytoplasmic mouth of the open pore. Although the concentrations necessary to block hERG channels are relatively high, AZA-induced blockage may prove to contribute to the toxicological properties of the AZAs.

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“…Toxin that this species produce is called azaspiracid. It have been described that effects of azaspiracids could be related to cytoskeletal changes, such as E-cadherin degradation, caspase activation / apoptosis, membrane cholesterol reduction, or gene expression alterations (Vilarino, 2008). The highest content of this toxin is accumulation in digestive gland (James et al, 2008).…”

Section: Azaspiracid Shellfish Poisoningmentioning

confidence: 99%