Bcl-2 can promote p53-dependent senescence versus apoptosis without affecting the G1/S transition
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With the aim to identify events involved in the determination of p53-dependent apoptosis versus growth arrest, we used rat embryo fibroblasts expressing a temperature-sensitive mutant (tsA58) of the SV40 large tumour antigen (LT). Heat-inactivation of LT leads to p53 activation and commitment to a senescent-like state (REtsA15 cell line) or apoptosis (REtsAF cell line). We report that senescence is associated with high levels of the anti-apoptotic Bcl-2 protein and a cell cycle arrest in G1 phase, whereas apoptosis is associated with low levels of Bcl-2 and a cell cycle arrest in G2 phase. Here we show that Bcl-2, which can inhibit apoptosis and proliferation, turns the apoptotic phenotype into a senescent-like phenotype in G2 phase. This result suggests that Bcl-2-dependent inhibition of apoptosis could be crucial for the commitment to replicative senescence, whereas its ability to inhibit G1 progression would not be required.
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Cellular senescence serves as a fail-safe mechanism against the transforming activity of antiapoptotic oncogenes.
“Another tumor suppressor response, called cellular senescence, serves as a fail-safe mechanism against the transforming activity of antiapoptotic oncogenes (29, 40, 43).”
From Mitochondrial Dysfunction Contributes to Oncogene-Induced Senescence (2009) · cites this paper as [40]
The Results (p. 7) show that Bcl-2 overexpression turned apoptosis into a senescent-like phenotype in rat fibroblasts. The Discussion (p. 9) notes the paradox that Bcl-2 promotes senescence despite being an oncogene. The paper does not establish that senescence generally serves as a fail-safe against the transforming activity of antiapoptotic oncogenes. (LLM, conf=0.84)
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The Rb/E2F pathway: expanding roles and emerging paradigms
Harbour, J. W., & Dean, D. C. (2000) · Genes & Development · doi:10.1101/gad.813200 · Cited by 1,153 · see citing works
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- [23][23] G.P. Dimri, X. Lee, G. Basile, M.Acosta, G. Scott, C. Roskelley, E.E. Medrano, M. Linskens, I. Rubelj, O. Pereira-Smith. et al. A biomarker that identifies senescent human cells in culture and in aging skin in vivo, Proc. Natl. Acad. Sci. USA 92 (1995) 9363-9367.
- [25][25] J.L. Vayssière, P.X. Petit, Y. Risler, B. Mignotte, Commitment to apoptosis is associated with changes in mitochondrial biogenesis and activity in cell lines conditionally immortalized with Simian Virus 40, Proc. Natl. Acad. Sci. USA 91 (1994) 11752-11756.
- [30][30] X.Q. Qin, D.M. Livingston, W.G. Jr Kaelin, P.D. Adams, Deregulated transcription factor E2F-1 expression leads to S-phase entry and p53-mediated apoptosis, Proc. Natl. Acad. Sci. USA 91 (1994) 10918-10922. FIG. 1. Analysis of REtsA15 and REtsAF phenotype at 39.5°C. (a) REtsA15 and REtsAF cells were incubated at 39.5°C. REtsA15 cells (●) progressively stop to proliferate and harbour a senescent-like morphology whereas REtsAF cells (■) are detached from the culture dish and harbour an apoptotic-like phenotype (photographs were taken 48h after shift at 39.5°C). (b) A flow cytometric analysis of cell death was performed on both cell lines after 48h at 39.5°C. The cytograms obtained with REtsA15 and REtsAF cells show three distinct populations of cells: surviving, apoptotic and necrotic cells. REtsAF cells undergo a massive apoptotic cell death while most of REtsA15 cells remain alive. <!-- image --> FIG. 2. Analysis of bax and bcl-2 expression in REtsAF and REtsA15 cells. RT-PCR and Western-blot analysis were performed to study expression of the bax and bcl-2 genes. RTPCR was used to characterise mRNA levels (a). For bax , similar basal levels were found in both cell lines whereas higher levels were observed for REtsAF cells at 39.5°C. For bcl-2 , higher levels were observed for REtsA15 at 33°C and 39.5°C. Western-blot analysis (b) reveal that the Bax protein equally accumulates in both cell lines at 39.5°C whereas the amount of Bcl-2 is always superior in REtsA15 cells. <!-- image --> FIG. 3. Analysis of p21 Waf-1/Sdi-1/Cip1 expression and Rb phosphorylation. Western-blot analysis were performed to characterise the level of p21 Waf-1/Sdi-1/Cip1 protein and Rb phosphorylation at 33°C and 39.5°C. The p21 Waf-1/Sdi-1/Cip1 protein accumulates in both cell lines at 39.5°C. The analysis of Rb also shows that it accumulates in both cell lines at 39.5°C. A long time exposure (a) allows to distinguish the hypophosphorylated (p105), phosphorylated (p110) and hyperphosphorylated (p115) forms of Rb in both cell lines at 33°C. A short time exposure (b) shows that p105, the hypophosphorylated and active form of Rb disappears in REtsAF cells at 39.5°C whereas it accumulates in REtsA15 cells. <!-- image --> FIG. 4. Analysis of DNA synthesis and cell cycle regulation in REtsAF and REtsA15 cells. DNA synthesis was estimated by measuring BrdU incorporation at 33°C and 39.5°C by flow cytometry. The percentage of BrdU positive cells strongly decreases in both REtsA15 and REtsAF cells at 39.5°C but decreases more rapidly in REtsA15 cells than in REtsAF (a). The distribution of REtsAF and REtsA15 cells in the different phases of cell cycle, is identical at 33°C (b). At 39.5°C, the proportion of REtsAF and REtsA15 cells in S phase decreases but REtsAF cells accumulate in G2/M phases whereas REtsA15 cells essentially accumulate in G1 phase. <!-- image --> <!-- image --> FIG. 5. Characterisation of the REtsAF-Bcl-2 phenotype at 39.5°C. Analysis of cell death (a) reveals that REtsAF-Bcl-2 cells at 39.5°C are essentially surviving cells. A photograph of REtsAF-Bcl-2 cells at 39.5°C (b) shows a senescent-like morphology and a Western-blot analysis shows a small accumulation of Bax, a strong accumulation of p21 Waf-1/Sdi-1/Cip1 and an hyperphosphorylation of Rb, similar to those observed in REtsAF cells at 39.5°C. Finally, bcl2 overexpression does not seem to modify significantly DNA synthesis (d) and cell cycle regulation (e) when compared to Figure 4.
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Mitochondrial Dysfunction Contributes to Oncogene-Induced Senescence
Moiseeva, O., Bourdeau, V., Roux, A., Deschênes-Simard, X., & Ferbeyre, G. (2009) · Molecular and Cellular Biology · doi:10.1128/mcb.01868-08 · Cited by 408 · see citing works
Senescent cells: a therapeutic target for cardiovascular disease
Childs, B. G., Li, H., & van Deursen, J. M. (2018) · Journal of Clinical Investigation · doi:10.1172/jci95146 · Cited by 192 · see citing works
Cell senescence and hypermitogenic arrest
Blagosklonny, M. V. (2003) · The EMBO Reports · doi:10.1038/sj.embor.embor806 · Cited by 156 · see citing works
- Authors
- Rincheval, V., Renaud, F., Lemaire, C., Godefroy, N., Trotot, P., Boulo, V., Mignotte, B., & Vayssière, J.-L.
- Affiliations
- Centre National de la Recherche Scientifique (FR)
- École Pratique des Hautes Études (FR)
- Corresponding author
- Vayssière, Jean-Luc
- Venue
- Biochemical and Biophysical Research Communications
- Publisher
- Elsevier BV
- Published
- 2002-10
- Volume
- 298
- Issue
- 2
- Pages
- 282-288
- ISSN
- 0006-291X (ISSN-L)
- OpenAlex
- W2070655871
- Cited by
- 46
- References
- 1
- Citations by year
- 2023: 3 · 2022: 4 · 2021: 2 · 2020: 1 · 2018: 2 · 2015: 1 · 2014: 1 · 2013: 1 · 2012: 2
- FWCI
- 2.60
- Type
- journal article
- Language
- en
- Open access
- green
- hal.science
- Licence
- Locations
- Biochemical and Biophysical Research Communications (publishedVersion)
- PubMed (publishedVersion)
- HAL (submittedVersion, other-oa)
- Topics
- Health Sciences › Medicine › Physiology › Telomeres, Telomerase, and Senescence
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Cell death mechanisms and regulation
- Health Sciences › Medicine › Oncology › Cancer-related Molecular Pathways
- Keywords
- Bcl-2, p53, replicative senescence, apoptosis, G1/S transition, cell cycle arrest, G2 phase, temperature-sensitive SV40 large T antigen, rat embryo fibroblasts, growth arrest, anti-apoptotic proteins
- MeSH terms
- Animals, Cell Line, DNA, Fibroblasts, Phenotype, RNA, Messenger, Temperature, Tumor Suppressor Protein p53, G1 Phase, S Phase, Cellular Senescence, Apoptosis, Proto-Oncogene Proteins c-bcl-2, Rats
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