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Changes in microtubule organization after exposure to a benzimidazole derivative in Chinese hamster cells
C Pisano1, A Battistoni, A Antoccia
1Research and Development, Sigma-Tau, Pomezia, Rome, Department of Genetics and Molecular Biology, University 'La Sapienza', Rome, Italy.
Abstract:
Many aneugenic compounds are known to affect one or several components of the mitotic apparatus. The mechanisms and targets of the aneuploidy-inducing activity of the benzimidazole derivative thiabendazole remain uninvestigated. In our experiments we found that thiabendazole-treated Chinese hamster cells (Cl-1) exhibited low levels of newly synthesized tubulin, indicating microtubule poisoning. In addition, microtubule growth and organization were substantially affected at mitosis. This was revealed by the reduced length of both interpolar and astral microtubules. Furthermore, thiabendazole strongly induced multipolar and asymmetric alpha-tubulin-positive metaphase spindles, characterized, however, by the absence of fragmentation of centrosome material as evaluated by anti-gamma-tubulin antibody staining. Interestingly, we found that microtubule poisoning induced by thiabendazole was qualitatively different from that of colchicine, the best known microtubule depolymerizing agent. In fact, in interphase cells colchicine was comparatively more effective than thiabendazole in promoting depolymerization of cytoplasmic microtubules. However, colchicine could not depolymerize a sub-population of stable, acetylated microtubules, which were however significantly reduced after thiabendazole exposure. In conclusion, the capability of thiabendazole to promote chromosomal malsegregation could be related to an effect on microtubule polymerization that specifically promotes formation of aberrant spindles.
Insights
Thiabendazole, a benzimidazole derivative, causes aneuploidy by disrupting microtubule polymerization and forming aberrant spindles. Unlike colchicine, it affects stable, acetylated microtubules, leading to chromosomal malsegregation.
Area of Science:
- Cell Biology
- Molecular Toxicology
Background:
- Aneuploidy-inducing compounds often target the mitotic apparatus.
- The specific mechanisms of thiabendazole's aneuploidy induction were previously uninvestigated.
Purpose of the Study:
- To investigate the mechanisms and targets of thiabendazole's aneuploidy-inducing activity.
- To compare thiabendazole's effects on microtubules with colchicine.
Main Methods:
- Treatment of Chinese hamster cells (Cl-1) with thiabendazole.
- Analysis of tubulin synthesis, microtubule organization, and spindle morphology.
- Evaluation of centrosome material using anti-gamma-tubulin antibody staining.
- Comparison with colchicine's effects on cytoplasmic and stable microtubules.
Main Results:
- Thiabendazole treatment led to reduced tubulin synthesis and impaired microtubule growth and organization.
- Aberrant, multipolar, and asymmetric metaphase spindles were observed without centrosome fragmentation.
- Thiabendazole affected stable, acetylated microtubules, unlike colchicine.
- Thiabendazole's microtubule poisoning differed qualitatively from colchicine's.
Conclusions:
- Thiabendazole induces aneuploidy through an effect on microtubule polymerization, promoting aberrant spindle formation.
- Its distinct mechanism involves targeting stable microtubules, contributing to chromosomal malsegregation.