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Telomere erosion-induced mitotic catastrophe in continuously grown chinese hamster don cells
Sea H Sohn1, Asha S Multani, Pankaj K Gugnani
1Department of Animal Science and Biotechnology, Chinju National University, Chinju, 660-758, Republic of Korea.
Abstract:
We have previously reported that telomere erosion is the earliest chromatin modification in cells entering the apoptotic pathway. The purpose of this investigation was to determine whether loss of telomeric DNA was involved in inducing mitotic catastrophe and death in Chinese hamster Don cells. Don, a male Chinese hamster-derived cell line which requires daily subculturing to remain diploid, was grown without subculturing for 1-4 days at 37 degrees C and analyzed cytologically. Our results indicated that (1) the frequency of metaphase chromosomes with structural anomalies was significantly higher in 3-day continuously grown cells than in 1-day control cells (8.2% vs 5.7%; P < 0.01), (2) the mitotic index was considerably lower in 3-day continuously grown cells (0.13%) than in control cells (3.64%), (3) cells grown for 3 days continuously showed a higher incidence (7.6%) of endoreduplicated metaphase chromosomes than did control cells (4.9%), (4) 4-day continuously grown Don cells showed significantly smaller amounts of telomeric DNA in interphase nuclei than did control cells, and (5) apoptotic cells were more frequent in 4-day cell cultures (40.6%) than in control cells (4.3%). These results support our earlier observations and contribute additional support for our hypothesis that telomere reduction is the cause of mitotic catastrophe and that cell death in continuously grown Don cells occurs because of the loss of telomeric DNA.
Insights
Telomere erosion, the loss of telomeric DNA, triggers mitotic catastrophe and cell death in Chinese hamster Don cells. This study confirms telomere reduction as the cause of cell death in continuously cultured cells.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- Telomere erosion is an early chromatin modification preceding apoptosis.
- Chinese hamster Don cells require subculturing to maintain diploidy.
Purpose of the Study:
- To investigate if telomeric DNA loss induces mitotic catastrophe and cell death in Chinese hamster Don cells.
- To establish the role of telomere reduction in cell death pathways.
Main Methods:
- Chinese hamster Don cells were cultured without subculturing for 1-4 days.
- Cytological analysis was performed to assess chromosomal anomalies, mitotic index, and endoreduplication.
- Telomeric DNA content in interphase nuclei and apoptotic cell frequency were quantified.
Main Results:
- Continuously grown cells showed increased chromosomal structural anomalies and endoreduplication.
- Mitotic index significantly decreased in continuously grown cells.
- 4-day cultures exhibited reduced telomeric DNA and a higher incidence of apoptosis (40.6% vs 4.3%).
Conclusions:
- Telomere reduction is a causative factor in mitotic catastrophe.
- Loss of telomeric DNA leads to cell death in continuously cultured Don cells.
- Findings support the hypothesis linking telomere shortening to cell death mechanisms.