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12:04
Examination of Mitotic and Meiotic Fission Yeast Nuclear Dynamics by Fluorescence Live-cell Microscopy
Published on: June 24, 2019
Generation of micronuclei during interphase by coupling between cytoplasmic membrane blebbing and nuclear budding
Koh-ichi Utani1, Atsushi Okamoto, Noriaki Shimizu
1Graduate School of Biosphere Science, Hiroshima University, Higashi-hiroshima, Hiroshima, Japan.
Plos One
|November 11, 2011
Summary
Nuclear budding extrudes chromatin, forming lamin B1-negative micronuclei during interphase. Cytoplasmic membrane blebbing drives this process, potentially impacting cancer cell genomes.
Area of Science:
- Cell Biology
- Genomics
- Cancer Research
Background:
- Micronucleation via interphase nuclear budding remains poorly understood.
- Lamin B1-negative micronuclei have been observed, but their formation mechanism is unclear.
Purpose of the Study:
- To elucidate the mechanism of interphase nuclear budding and micronuclei formation.
- To investigate the role of cytoplasmic membrane dynamics in nuclear envelope rupture and chromatin extrusion.
Main Methods:
- Established a live-cell line to visualize lamin B1 and extrachromosomal DNA simultaneously.
- Utilized time-lapse microscopy to observe nuclear budding and micronuclei formation in real-time.
- Induced cytoplasmic blebbing using serum or camptothecin to study its effect on nuclear budding.
Main Results:
- Confirmed the presence of lamin B1-negative micronuclei, often entrapped in cytoplasmic blebs connected by chromatin stalks.
- Observed simultaneous cytoplasmic blebbing and nuclear content extrusion, leading to lamin B1-negative micronuclei formation during interphase.
- Demonstrated that induced blebbing rapidly triggers nuclear budding, particularly during S phase, and preferentially extrudes smaller chromatin fragments.
Conclusions:
- Proposed a novel mechanism where cytoplasmic membrane dynamics pull chromatin out through nuclear lamina breaks.
- Provided evidence for this mechanism in cancer cell lines (COLO 320, HeLa).
- Highlighted the potential for this process to cause genomic instability and affect cancer phenotypes.
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