Cytoskeletal toxicity of pectenotoxins in hepatic cells
B Espiña1, M C Louzao, I R Ares
1Departamento de Farmacologia, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain.
Background And Purpose:
Pectenotoxins are macrocyclic lactones found in dinoflagellates of the genus Dinophysis, which induce severe liver damage in mice after i.p. injection. Here, we have looked for the mechanism(s) underlying this hepatotoxicity.
Experimental Approach:
Effects of pectenotoxin (PTX)-1, PTX-2, PTX-2 seco acid (PTX-2SA) and PTX-11 were measured in a hepatocyte cell line with cancer cell characteristics (Clone 9) and in primary cultures of rat hepatocytes. Cell morphology was assessed by confocal microscopy; F- and G-actin were selectively stained and cell viability measured by Alamar Blue fluorescence.
Key Results:
Clone 9 cells and primary hepatocytes showed a marked depolymerization of F-actin with PTX-1, PTX-2 and PTX-11 (1-1000 nM) associated with an increase in G-actin level. However, morphology was only clearly altered in Clone 9 cells. PTX-2SA had no effect on the actin cytoskeleton. Despite the potent F-actin depolymerizing effect, PTX-1, PTX-2 or PTX-11 did not decrease the viability of Clone 9 cells after 24-h treatment. Only prolonged incubation (> 48 h) with PTXs induced a fall in viability, and under these conditions, morphology of both Clone 9 and primary hepatocytes was drastically changed.
Conclusions And Implications:
Although the actin cytoskeleton was clearly altered by PTX-1, PTX-2 and PTX-11 in the hepatocyte cell line and primary hepatocytes, morphological assessments indicated a higher sensitivity of the cancer-like cell line to these toxins. However, viability of both cell types was not altered.
Insights
Pectenotoxins (PTXs) disrupt the actin cytoskeleton in liver cells, but do not immediately impact cell viability. Prolonged exposure to PTXs alters cell morphology, with cancer-like cells showing higher sensitivity.
Area of Science:
- Marine Toxinology
- Hepatology
- Cell Biology
Background:
- Pectenotoxins (PTXs) are marine toxins from Dinophysis species.
- PTXs are known to cause severe liver damage in animal models.
- The precise mechanisms of PTX hepatotoxicity require elucidation.
Purpose of the Study:
- To investigate the cellular mechanisms of pectenotoxin-induced hepatotoxicity.
- To assess the effects of PTXs on the actin cytoskeleton and cell viability in hepatocytes.
Main Methods:
- Hepatotoxicity assays using a rat hepatocyte cell line (Clone 9) and primary rat hepatocytes.
- Confocal microscopy to evaluate cell morphology.
- Staining for F-actin and G-actin to analyze cytoskeleton dynamics.
- Alamar Blue fluorescence assay to measure cell viability.
Main Results:
- PTX-1, PTX-2, and PTX-11 induced significant F-actin depolymerization and G-actin increase in both cell types.
- Morphological alterations were more pronounced in the Clone 9 cell line.
- PTX-2 seco acid (PTX-2SA) did not affect the actin cytoskeleton.
- Cell viability remained unaffected after 24-hour PTX exposure, but decreased after prolonged incubation (>48 hours).
Conclusions:
- Pectenotoxins disrupt the actin cytoskeleton in hepatocytes, with varying sensitivity between normal and cancer-like cell lines.
- While PTXs alter cell morphology, they do not cause acute cell death.
- Prolonged PTX exposure is required to induce significant cytotoxicity and morphological changes in hepatocytes.
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