The development of cellular senescence is not consistent in cultured bovine fibroblasts. Numerous factors may be contributing to the variable onset of cellular senescence, including oxidative stress, telomere shortening and DNA damage. Recent results indicate that cellular senescence is also associated with markers of DNA replication. This suggests that cells may be more likely to enter a senescent state depending on their cell cycle progression. The purpose of this study was to determine the effect of cell cycle phase on the development of stress-induced premature cellular senescence (SIPS). Bovine fibroblasts were synchronized at various cell cycle phases, followed by treatment with increasing doses of H2O2. Senescent cells were detected using SA-β-galactosidase staining assay. As H2O2 dosage increased, the amount of cell death by necrosis increased in both unsynchronized and cell cycle synchronized groups, while the amount of senescence varied depending on cell cycle phase. Our results suggest that the S phase of the cell cycle is the most resistant to oxidative damage, the G2/M phase is the most susceptible, and the G1/S phase is the most likely to enter senescence as a protective measure following low doses of H2O2. Increased senescence also resulted from an increased recovery time post-H2O2 treatment, and gene expression studies suggest SIPS bovine fibroblasts senesce via the p53-independent pathway. An improved understanding of SIPS has important implications for improving cloning efficiency and understanding age-related diseases.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OGU.10214/2956 |
| Date | 02 September 2011 |
| Creators | Hunt, Andrea |
| Contributors | Madan, Pavneesh |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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