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Title: p53 and responses to DNA damage in small airway epithelium
Author: Armit, Christopher James
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2001
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The effects of p53 were investigated in a mouse model of acute lung injury and in short-term primary cultures of isolated Clara cells. Gene targeted mice, germline deficient in p53, were exposed to γ-irradiation and compared to wild type controls. The in vivo response was to DNA damage was characterised in terms of growth arrest, apoptosis, morphology, and gene expression. An acute stress response was observed in vivo, and localised to a subpopulation of the lung epithelium, the bronchiolar cells. p53 was stabilised in this population and was associated with transcriptional induction of Bax, but not other bcl-2 family members. p53 deficient mice did not display this rapid accumulation of Bax transcripts, as assessed by RNase Protection Assay. Within wild type and p53 null mice, γ-irradiation did not induce apoptosis in lung epithelial cells at any timepoints studied, as assessed by morphology, but induce strand breaks that were detectable by TUNEL. Cell cycle activity as assessed by BrdU incorporation, was infrequent in the lung at all timepoints, regardless of p53 status, and hence an effect of p53 on cell cycle progression was not detected in vivo. The effects of p53-deficiency was additionally investigated in short-term primary cultures of murine bronchiolar Clara cells. Culturing of Clara cells allowed an assessment of the functional consequences of p53 deficiency in proliferating cells. Clara cells, isolated from gene-targeted p53-deficient mice, were compared to cells derived from wild type littermates. Baseline proliferation rates, as determined by BrdU incorporation, were similar irrespective of p53 status. p53 null cultures displayed abnormal morphology; specifically, a high incidence of multinucleation, which increased with time in culture. Multinucleated cells maintained expression of the Clara cell marker for CC10, and were proficient in S phase DNA synthesis, as determined by BrdU incorporation. Nucleation defects in p53 -/- Clara cells associated with abnormalities in mitosis and cytokinesis, as documented by time-lapse videomicroscopy, and with increased centrosome number, determined by confocal microscopy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available