| External factors: | Hyperoxia |
| Aging type: | Accelerate |
| Aging characteristic: |
| Category: | Other |
| Phenotype: | Aging |
| Experiment: | Cell morphological analysis//SA-β-gal activity assay |
| Description: | Unlike PHLFs grown in 21% O2, those cultured in 70% O2 displayed a marked growth arrest, as indicated by reduced number of cells seen per field, and enlarged, flattened phenotype associated with senescence.Approximately 10% of untreated cells stained blue, while 80% stained blue in the PHLF population exposed to 70% O2. |
| Regulatory pathway: | p53-p21//p16-pRb |
| R-EF-Pathway: | --//-- |
| Official symbol(s): | TP53-CDKN1A// |
| Pathway experiment: | Western blot//SA-β-gal activity assay |
| Pathway description: | We suppressed p53 function by overexpressing a dominant negative p53 (DN-p53) in a retroviral vector, which resulted in effective suppression of p21 expression .PHLFs overexpressing DN-p53 showed a significant decrease in the number of β-galactosidase-positive cells after 70% O2 exposure compared to PHLFs expressing empty vector. To test for the requirement of both the p53/p21 and p16/pRb pathways under hyperoxia, we overexpressed the HPV proteins E6 (which suppresses p53 function;ref. 42)and E7 together in the same cells. While ～70% of the PHLFs expressing vector controls senesced under 70% O2, only 20% of E6/E7 expressing PHLFs underwent senescence. |
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