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dc.contributor.advisorDrake, Mandyen
dc.contributor.advisorMeehan, Richarden
dc.contributor.authorRose, Catherine Margareten
dc.date.accessioned2017-04-10T14:02:01Z
dc.date.available2017-04-10T14:02:01Z
dc.date.issued2015-07-04
dc.identifier.urihttp://hdl.handle.net/1842/21082
dc.description.abstractFetal exposure to excess glucocorticoid is associated with low birth weight and increased cardiovascular disease risk in first generation offspring. Such phenotypes can be produced experimentally through the administration of the synthetic glucocorticoid dexamethasone (Dex) to pregnant rats during the last week of gestation. These ‘programmed effects’ can be transmitted to a second generation through both maternal and paternal lines. The overall hypothesis for this thesis was that the transmission of programmed effects through the male line may result from alterations in fetal germ cells, which form sperm in adulthood. Epigenetic reprogramming of germ cells is characterised by the genome-wide erasure and subsequent re-establishment of 5-methylcytosine (5mC), however this process has not previously been described for the rat. Furthermore, the involvement of more recently identified cytosine modifications; 5-hydroxymethylcytosine (5hmC), 5- formylcytosine (5fC) and 5-carboxylcytosine (5caC), has not been characterised during germ cell ontogeny. Using immunofluorescence to study DNA modifications during late gestation I identified that 5hmC, 5fC and 5caC were present between e14.5 and e16.5 but absent thereafter. In contrast, 5mC was absent during this time but remethylation was noted from e19.5 onwards. Prenatal Dex exposure was associated with the presence of significantly more 5mC-positive germ cells at e19.5 relative to controls. This difference did not persist at e20.5 suggesting that Dex exposure promotes premature global remethylation. The mechanisms for this are unclear since there were no differences between groups in the localisation of the DNA methyltransferases DNMT3a and 3b, or in markers of normal testis maturation. To enable the study of gene-specific changes in DNA methylation in the germline a colony of Germ Cell Specific-Enhanced Green Fluorescent Protein (GCS-EGFP) rats was established and characterised. GCS-EGFP rats had a transgenerational decrease in pup weight with Dex exposure, as in Wistar rats. The expression of both established and novel candidate genes was compared between strains. Multiple genes across different pathways had altered expression, with some affected in both Wistar and GCS-EGFP rats, whilst other differences were strain-specific. Enhanced Reduced Representation Bisulfite Sequencing was performed on liver and fetal germ cells from males exposed to Dex in utero to explore effects on DNA methylation. These studies confirm that epigenetic reprogramming occurs in the rat and that this process may be susceptible to modification by prenatal Dex exposure. GCS-EGFP rats also exhibited a Dex programming phenotype, with decreased pup weight and altered liver gene expression. The use of this unique strain of rats will permit dissection of the mechanisms for the transmission of programmed phenotypes across generations.en
dc.contributor.sponsorotheren
dc.language.isoen
dc.publisherThe University of Edinburghen
dc.relation.hasversionRose CM, van den Driesche S, Sharpe RM, Meehan RR, Drake AJ (2014) Dynamic changes in DNA modification states during late gestation male germ line development in the rat. Epigenetics & Chromatin 7:1-15en
dc.relation.hasversionRose CM, van den Driesche S, Meehan RR, Drake AJ (2013) Epigenetic reprogramming: preparing the epigenome for the next generation. Biochem Soc Trans 41: 809-814en
dc.subjectfetal programmingen
dc.subjectepigeneticsen
dc.subjectcardiovascular diseaseen
dc.subjectspermen
dc.titleProgramming of cardiovascular disease: an exploration of epigenetic mechanismsen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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