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Mitotic inhibition and chromosome displacement induced by estradiol in Chinese hamster cells
Abstract:
We tested diethylstilbestrol (DES) and 17 beta-estradiol as mitotic arrestants to determine their effects on chromosome distribution, spindle microtubules, and the cytoplasmic microtubule complex (CMTC) in the Chinese hamster strain Don. Cytological experiments assessed micronuclei induction, chromosome displacement, and anaphase recovery. Indirect immunofluorescence microscopy with antibody to tubulin and electron microscopy were used to illustrate effects on microtubules. Both DES and estradiol were potent inhibitors of mitosis when applied to cells in vitro. Estradiol induced micronuclei at a greater frequency than did DES. Estradiol-arrested metaphases often contained misaligned chromosomes despite the presence of a bipolar spindle and an equatorial plate. Equatorial plates were not observed in DES-arrested cells. Cells recovered quickly from estradiol exposure upon removal of the steroid. The frequency of abnormal metaphases and abnormal anaphases declined as the recovery period increased. Microtubule experiments showed that DES inhibited spindle assembly and disassembled the CMTC, whereas estradiol, at similar concentrations, arrested mitosis in a manner that allowed spindle assembly. A definite effect on the CMTC by estradiol could not be determined. However, changes in cell morphology were observed. In the presence of estradiol, centrosomes organized microtubules that joined with kinetochores of chromosomes at the equatorial plate as well as with those of misaligned chromosomes. Misaligned chromosomes appeared predominantly at polar regions of mitotic cells. Following drug removal, the pole-oriented chromosomes reoriented at the equatorial plate. The unique arresting properties of estradiol may prove useful in studies of chromosome migration and segregation during mitosis.
Insights
Diethylstilbestrol (DES) and 17 beta-estradiol are potent mitotic inhibitors. Estradiol arrests mitosis with spindle assembly, while DES disrupts it, offering distinct research applications.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Diethylstilbestrol (DES) and 17 beta-estradiol are known endocrine disruptors.
- Their effects on mitosis, particularly microtubule dynamics and chromosome segregation, require detailed investigation.
Purpose of the Study:
- To compare the effects of DES and 17 beta-estradiol on mitosis in Chinese hamster cells.
- To elucidate their distinct mechanisms of action on spindle microtubules and chromosome distribution.
Main Methods:
- Cytological analysis including micronuclei induction, chromosome displacement, and anaphase recovery.
- Indirect immunofluorescence and electron microscopy to visualize microtubule organization.
- In vitro cell exposure to DES and 17 beta-estradiol.
Main Results:
- Both DES and estradiol potently inhibited mitosis.
- Estradiol induced higher micronuclei frequency and arrested cells with misaligned chromosomes but intact spindles.
- DES inhibited spindle assembly and disassembled cytoplasmic microtubule complex (CMTC), preventing equatorial plate formation.
Conclusions:
- Estradiol arrests mitosis allowing spindle assembly, with potential applications in studying chromosome segregation.
- DES inhibits spindle assembly and CMTC, providing a different model for mitotic disruption.
- Differential effects highlight distinct mechanisms of action for these steroids on cell division.