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Chromatin Immunoprecipitation in the Cnidarian Model System Exaiptasia diaphana
Published on: March 17, 2023
Comparative study of cyanotoxins affecting cytoskeletal and chromatin structures in CHO-K1 cells
Mariann Gácsi1, Otilia Antal, Gábor Vasas
1Department of Experimental Zoology, Balaton Limnological Research Institute, Hungarian Academy of Sciences, Tihany, Hungary.
Abstract:
In this study we compared the effects of the two frequently occuring and most dangerous cyanobacterial toxins on the cellular organization of microfilaments, microtubules and on the chromatin structure in Chinese hamster ovary (CHO-K1) cells. These compounds are the widely known microcystin-LR (MC-LR) and cylindrospermopsin (CYN) classified as the highest-priority cyanotoxin. Toxic effects were tested in a concentration and time dependent manner. The hepatotoxic MC-LR did not cause significant cytotoxicity on CHO-K1 cells under 20 microM, but caused apoptotic changes at higher concentrations. Apoptotic shrinkage was associated with the shortening and loss of actin filaments and with a concentration dependent depolymerization of microtubules. No necrosis was observed over the concentration range (1-50 microM MC-LR) tested. Cylindrospermopsin did cause apoptosis at low concentrations (1-2 microM) and over short exposure periods (12h). Necrosis was observed at higher concentrations (5-10 microM) and following longer exposure periods (24 or 48h). Cyanotoxins also affected the chromatin structure. The condensation process was inhibited by MC-LR at a later stage and manifested as broken elongated prechromosomes. CYN inhibited chromatin condensation at the early fibrillary stage leading to blurred fluorescent images of apoptotic bodies and preventing the formation of metaphase chromosomes. Cylindrospermopsin exhibited a more pronounced toxic effect causing cytoskeletal and nuclear changes as well as apoptotic and necrotic alterations.
Insights
This study reveals that cyanotoxins microcystin-LR (MC-LR) and cylindrospermopsin (CYN) disrupt cell structure. Cylindrospermopsin (CYN) is more toxic, causing significant cytoskeletal, nuclear, and cell death changes in CHO-K1 cells.
Area of Science:
- Environmental toxicology
- Cell biology
- Biochemistry
Background:
- Cyanobacteria produce potent toxins, including microcystin-LR (MC-LR) and cylindrospermopsin (CYN).
- These toxins are classified as high-priority due to their prevalence and danger.
- Understanding their cellular effects is crucial for risk assessment.
Purpose of the Study:
- To compare the toxic effects of MC-LR and CYN on Chinese hamster ovary (CHO-K1) cells.
- To investigate the impact of these cyanotoxins on cytoskeletal organization (microfilaments, microtubules) and chromatin structure.
- To determine the concentration and time-dependent toxicity of MC-LR and CYN.
Main Methods:
- Exposure of CHO-K1 cells to varying concentrations and durations of MC-LR and CYN.
- Microscopic analysis of cellular organization, focusing on actin filaments, microtubules, and chromatin.
- Assessment of cellular damage, including apoptosis and necrosis.
Main Results:
- MC-LR induced apoptosis at higher concentrations (>20 microM) with actin and microtubule disruption, but no necrosis.
- CYN caused apoptosis at lower concentrations (1-2 microM) and short exposures (12h), progressing to necrosis at higher concentrations (5-10 microM) and longer exposures (24-48h).
- Both toxins affected chromatin condensation; MC-LR disrupted later stages, while CYN interfered with early stages, preventing metaphase chromosome formation.
Conclusions:
- Cylindrospermopsin (CYN) demonstrates more potent toxicity than microcystin-LR (MC-LR).
- CYN induces significant cytoskeletal and nuclear alterations, leading to both apoptosis and necrosis.
- Both MC-LR and CYN pose a threat to cellular integrity, with distinct mechanisms of chromatin disruption.
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