Targeting Chloride Ion Channels: New Insights into the Mechanism of Action of the Marine Toxin Azaspiracid

Abstract

Azaspiracids (AZAs) are marine toxins produced by dinoflagellates belonging to the genera Azadinium and Amphidoma that caused human intoxications after consumption of contaminated fishery products, such as mussels. However, the exact mechanism for the AZA induced cytotoxic and neurotoxic effects is still unknown. In this study several pharmacological approaches were employed to evaluate the role of anion channels on the AZA effects that demonstrated that cellular anion dysregulation was involved in the toxic effects of these compounds. The results presented here demonstrated that volume regulated anion channels (VRACs) are affected by this group of toxins, and, because there is not any specific activator of VRACs besides the intracellular application of GTPγ-S molecule, this group of natural compounds could represent a powerful tool to analyze the role of these channels in cellular homeostasis. In addition to this, in this work, a detailed pharmacological approach was performed in order to elucidate the anion channels present in human HEK293 cells as well as their regulation by the marine toxins azaspiracids. Altogether, the data presented here demonstrated that the effect of azaspiracids in human cells was completely dependent on ATP-regulated anion channels, whose upregulation by these toxins could lead to regulatory volume decrease and underlie the reported toxicity of these compounds.

In Silico Simulations and Functional Cell Studies Evidence Similar Potency and Distinct Binding of Pacific and Caribbean Ciguatoxins

“…Human embryonic kidney cell line (HEK293) stably expressing the human Na v 1.6 alpha subunit of the sodium channels were kindly provided by Dr Andrew Powell (Glax-oSmithKline R&D, Stevenage, UK) cultured in DMEM/F12 medium supplemented with Glutamax, MEM non-essential amino acids solution (Gibco, 1% w/v), and 10% fetal bovine serum as previously described (Boente-Juncal et al 2021). Geneticin (Gibco) was added at a final concentration of 0.4 mg/mL to increase the expression of sodium channels.…”

Natural Polyether Ionophores and Their Pharmacological Profile

“…Azaspiracids ( 7 – 9 , AZAs) are a group of lipophilic polyether toxins produced by dinoflagellates belonging to the genera Azadinium and Amphidoma and are found in the shellfish and tunicates that accumulate them [ 51 , 52 , 53 , 54 ]. The AZAs induced cytotoxic and neurotoxic effects; however, the mechanism of action is still unknown [ 55 ].…”

Tetrodotoxin, a Potential Drug for Neuropathic and Cancer Pain Relief?

“…TTX is a potent neurotoxin, and as such, it can produce severe toxicity that can lead even to death. In fact, TTX is responsible for many human intoxications after ingestion of mainly puffer fish, but also of some molluscs such as mussels, oysters, clams or trumpet shellfishes largely in Asia, although recently, some cases have also been reported in Europe [ 80 ]. Symptoms and signs of people intoxicated with TTX include headache, diaphoresis, numbness, nausea, vomiting, abdominal pain, weakness, incoordination, hypotension, cardiac arrhythmias, muscle paralysis, and even death in the most critical cases [ 81 ].…”