Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/5157
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dc.contributor.advisorSlijepcevic, P-
dc.contributor.advisorKoi, M-
dc.contributor.authorCabuy, Erik-
dc.date.accessioned2011-05-24T12:57:19Z-
dc.date.available2011-05-24T12:57:19Z-
dc.date.issued2005-
dc.identifier.urihttp://bura.brunel.ac.uk/handle/2438/5157-
dc.descriptionThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 17/03/2005.en_US
dc.description.abstractTelomeres are nucleoprotein complexes located at the end of chromosomes. They have an essential role in protecting chromosome ends. Telomerase or ALT (alternative lengthening of telomeres) mechanisms maintain telomeres by compensating natural telomeric loss. We have set up a flow-FISH method and using mouse lymphoma cell lines we identified unexpectedly the presence of subpopulations of cells with different telomere lengths. Subpopulations of cells with different telomere lengths were also observed in a human ALT and non-ALT cell line. Differences in telomere length between subpopulations of cells were significant and we term this phenomenon TELEFLUCS (TElomere LEngth FLUctuations in Cell Subpopulations). By applying flow-FISH we could successfully measure telomere lengths during replicative senescence in human primary fibroblasts with different genetic defects that confer sensitivity to ionising radiation (IR). The results from this study, based on flow-FISH and Southern hybridisation measurements, revealed an accelerated rate of telomere shortening in radiosensitive fibroblasts. We also observed accelerated telomere shortening in murine BRCA1 deficient cells, another defect conferring radiosensitivity, in comparison with a BRCA1 proficient cell line. We transiently depleted BRCA1 by siRNAs in two human mammary epithelial cell lines but could not find changes in telomere length in comparison with control cells. Cytological evidence of telomere dysfunction was observed in all radiosensitive cell lines. These results suggest that mechanisms that confer sensitivity to IR may be linked with mechanisms that cause telomere dysfunction. Furthermore, we have been able to show that human ALT positive cell lines show dysfunctional telomeres as detected by either the presence of DSBs at their telomeres or cytogenetic analysis and usually cells with dysfunctional telomeres are sensitive to IR. Finally, we assessed hTERT mRNA splicing variants and telomerase activity in brain tumours, which exhibit considerable chromosome instability suggesting that DNA repair mechanisms may be impaired. We demonstrated that high levels of hTERT mRNAs and telomerase activity correlate with proliferation rate. The presence of hTERT splice variants did not strictly correlate with absence of telomerase activity but hTERT spliced transcripts were observed in some telomerase negative brain tumours suggesting that hTERT splicing may contribute to activation of ALT mechanisms.en_US
dc.description.sponsorshipGrant to Dr. Predrag Slijepcevic from the Department of Health (RRX97), UK; EC Euratom (Fig h-CT-2002-0021 7); Laboratory of Anatomy, Embryology, Histology and Medial Physics, Faculty of Medicine, University of Ghent, Belgiumen_US
dc.language.isoenen_US
dc.publisherBrunel University School of Health Sciences and Social Care PhD Theses-
dc.relation.ispartofSchool of Health Sciences and Social Care-
dc.relation.urihttp://bura.brunel.ac.uk/bitstream/2438/5157/1/FulltextThesis.pdf-
dc.subjectChromosomesen_US
dc.subjectALT (alternative lengthening of telomeres) mechanismsen_US
dc.subjectMouse lymphoma cell linesen_US
dc.subjectBrain tumoursen_US
dc.subjectHuman primary fibroblastsen_US
dc.titleInvestigations of telomere maintenance in DNA damage response defective cells and telomerase in brain tumoursen_US
dc.typeThesisen_US
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Dept of Life Sciences Theses

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