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Title: Transcriptional and post-transcriptional control of DNMT1 in oocytes and somatic cells
Author: Lau, Ho-Tak
ISNI:       0000 0004 2722 3618
Awarding Body: University of Ulster
Current Institution: Ulster University
Date of Award: 2010
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In mammals, the DNA methylation patterns are established by the de novo methyltransferases of the DNMT3 family and subsequently maintained DNMTl. The DNA methylation patterns of imprinted genes are established during gametogenesis. Many imprinted genes are found methylated on the maternal allele, and this modification is established during oocyte growth. My primary aim was to develop a simple in vitro system for culturing oocytes during the period of de novo methylation, which would allow us to access this critical developmental period and to manipulate the microenvironment by supplementing growth factors in order to examine the signalling required for initiating de novo methylation. In Chapter 2, I show the development of the primary follicles from primordial follicles in an in vitro environment. By addition of SCF, I confirmed that it acts as a major growth stimulant in early oocyte growth. However, follicular development was arrested at the primary follicle stage, probably due to the absence of a theca layer surrounding the follicle. Secondly, I wanted to investigate if DNA methylation could be established at imprinted genes and repeat sequences in cultured oocytes with a view to investigating factors responsible for these events. Chapter 3 revealed limited establishment of DNA methylation in the cultured oocytes. Chromatin staining illustrated improper chromatin remodelling of the oocytes which accompanied follicle developmental arrest, and may have blocked de novo methylation. Lastly, I aimed to determine whether Dnmtl expression is regulated posttranscriptionally by the cytoplasmic polyadenylation element present in its 3 'UTR. Results in Chapter 4 show the CPE enhances DNMTl expression and also suggest the importance of a 26nt long conserved region in regulating the gene.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available