Davis, T., Singhrao, S.K., Wyllie, F.S., Haughton, M.F., Smith, P.J., Wiltshire, M., Wynford-Thomas, D., Jones, C.J., Faragher, R.G.A. and Kipling, D. (2003) Telomere-based proliferative lifespan barriers in Werner-syndrome fibroblasts involve both p53-dependent and p53-independent mechanisms Journal of Cell Science, 116. pp. 1349-1357.
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Werner-syndrome fibroblasts have a reduced in vitro life span before entering replicative senescence. Although this has been thought to be causal in the accelerated ageing of this disease, controversy remains as to whether Werner syndrome is showing the acceleration of a normal cellular ageing mechanism or the occurrence of a novel Werner-syndrome-specific process. Here, we analyse the signalling pathways responsible for senescence in Werner-syndrome fibroblasts. Cultured Werner-syndrome (AG05229) fibroblasts senesced after ~20 population doublings with most of the cells having a 2N content of DNA. This was associated with hypophosphorylated pRb and high levels of p16Ink4a and p21Waf1. Senescent AG05229 cells re-entered the cell cycle following microinjection of a p53-neutralizing antibody. Similarly, production of the human papilloma virus 16 E6 oncoprotein in presenescent AG05229 cells resulted in senescence being bypassed and extended cellular life span. Werner-syndrome fibroblasts expressing E6 did not proliferate indefinitely but reached a second proliferative lifespan barrier, termed Mint, that could be bypassed by forced production of telomerase in post-M1 E6-producing cells. The conclusions from these studies are that: (1) replicative senescence in Werner-syndrome fibroblasts is a telomere-induced p53-dependent event; and (2) the intermediate lifespan barrier Mint is also a telomere-induced event, although it appears to be independent of p53. Werner-syndrome fibroblasts resemble normal human fibroblasts for both these proliferative lifespan barriers, with the strong similarity between the signalling pathway linking telomeres to cell-cycle arrest in Werner-syndrome and normal fibroblasts providing further support for the defect in Werner syndrome causing the acceleration of a normal ageing mechanism.
|Item Type:||Journal article|
|Uncontrolled Keywords:||Ageing; Cellular senescence; Oncoprotein; Microinjection; Telomerase|
|Subjects:||B000 Health Professions > B100 Anatomy Physiology and Pathology|
|DOI (a stable link to the resource):||10.1242/jcs.00331|
|Faculties:||Faculty of Science and Engineering > School of Pharmacy and Biomolecular Sciences|
|Depositing User:||editor spbs|
|Date Deposited:||08 Nov 2007|
|Last Modified:||21 May 2014 11:02|
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