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Published on: May 30, 2013
Disruption of cytoskeleton by methylmercury in cultured CHO cells
R Vignani1, C Milanesi, P Di Simplicio
1Department of Environmental Biology, Faculty of Science, University of Siena, Via Mattioli 4, 54100 Siena, Italy.
Abstract:
The effect of methylmercury (MM) on three main cytoskeletal components [i.e. microtubules (MT), microfilaments (MF) and intermediate filaments (IF)] and on specific biochemical parameters (i.e. glutathione transferase (GST), glutathione reductase (RED), glutathione peroxidase (GSH-Px), glyoxalase 1 (GLY 1) and total -SH groups (TSH) of the cytosolic fraction) was studied in cultured Chinese hamster ovary (CHO) cells. The experiments were conducted with increasing doses of MM (i.e. 1, 4 and 8 mum), using an exposure time of 16 hr; and with a fixed dose of MM (2 mum), using increasing exposure periods (i.e. 0-24 hr). The morphological changes observed by immunofluorescence seemed to indicate that MF were damaged as much as (if not more than) MT after 16 hr of exposure to 4 mum-MM. At a concentration of 1 mum, MM only affected MF. The time-course experiments revealed that IF as well as MF and MT were severely disorganized after 3 and 6 hr of incubation in the presence of 2 mum-MM. However, an obvious reorganization was observed after 24 hr of exposure. In experiments using increasing MM doses, changes in the enzymatic activities were less noticeable than those observed in the morphology; only a modest decrease in TSH and RED activities (<30%) was recorded at the highest dose of MM used (i.e. 8 mum). In contrast, increasing the time of exposure to MM induced changes in both the cytoskeletal structures and the biochemical parameters: the lowest RED activity and TSH were observed after 3-6 hr exposure; control values were obtained after an exposure period of 24 hr. Ultrastructural observations on cells treated with increasing doses of MM showed changes in plasmamembrane profile, cytoskeleton organization and mitochondrion structure. The results confirm that MM causes non-specific damage to CHO cells and suggest that a functional interaction may exist between GSH-dependent enzymes and cytoskeletal structures.
Insights
Methylmercury (MM) damages cytoskeletal components like microtubules and microfilaments in Chinese hamster ovary cells. This mercury compound also affects cellular biochemical parameters, suggesting interactions with cellular defense systems.
Area of Science:
- Cell Biology
- Toxicology
- Biochemistry
Background:
- Methylmercury (MM) is a potent neurotoxin with known cellular effects.
- Cytoskeletal integrity is crucial for cell structure and function.
- Glutathione-dependent enzymes play a role in cellular defense against toxins.
Purpose of the Study:
- To investigate the impact of methylmercury on cytoskeletal components (microtubules, microfilaments, intermediate filaments) in cultured Chinese hamster ovary (CHO) cells.
- To assess the effects of methylmercury on specific biochemical parameters, including glutathione transferase (GST), glutathione reductase (RED), glutathione peroxidase (GSH-Px), glyoxalase 1 (GLY 1), and total -SH groups (TSH).
- To explore potential interactions between methylmercury, cytoskeletal structures, and glutathione-dependent enzymes.
Main Methods:
- Cultured Chinese hamster ovary (CHO) cells were exposed to varying concentrations of methylmercury (1, 4, and 8 µM) for 16 hours.
- Cells were also exposed to a fixed concentration of methylmercury (2 µM) for increasing durations (0-24 hours).
- Immunofluorescence microscopy was used to observe cytoskeletal changes, while ultrastructural analysis examined cellular morphology. Biochemical assays measured enzyme activities and total -SH groups.
Main Results:
- Methylmercury exposure led to dose- and time-dependent morphological changes in cytoskeletal components, with microfilaments and microtubules being particularly affected.
- Significant disorganization of intermediate filaments, microfilaments, and microtubules was observed after 3-6 hours of exposure.
- Biochemical analyses showed modest decreases in total -SH groups and glutathione reductase activity at higher methylmercury doses, with more pronounced effects observed over time. A reorganization of cytoskeletal structures was noted after 24 hours.
- Ultrastructural observations revealed alterations in the plasma membrane, cytoskeleton, and mitochondria.
Conclusions:
- Methylmercury induces non-specific damage to Chinese hamster ovary cells.
- The findings suggest a potential functional interaction between glutathione-dependent enzymes and cytoskeletal structures in response to methylmercury toxicity.
- Cytoskeletal disruption is a key mechanism underlying methylmercury-induced cellular damage.
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