- Title
- Quality control mechanisms responsible for the maintenance of genomic integrity in the female germline
- Creator
- Martin, Jacinta
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- DNA is the genetic repository containing the necessary information for cellular viability, fate decisions and development. In the female germline, genetic integrity also underpins successful conception, embryonic development, pregnancy and the future health of the offspring. In spite of its importance, DNA remains a chemical entity prone to structural alteration. If left unresolved, these structural lesions have the potential to lead to mutation and broader-scale genomic aberrations, which may elevate the predisposition of individuals to non-communicable diseases in later life. While it is therefore likely that female germ cells possess a sophisticated suite of quality control mechanism to defend their genome, the precise nature of these defence systems is not well understood. Given this knowledge gap, the overall aim of the studies described within this thesis was to explore the endogenous DNA protection and repair machinery present in the mammalian oocyte and early embryo. In completing these studies, we have uncovered several novel protective strategies employed by the oocyte and early preimplantation embryo to safeguard their genomic integrity. These include the first evidence for a critical link between fertilisation and the synthesis of transmembrane transporter molecules belonging to the multidrug resistant protein family. Specifically, we implicate permeability glycoprotein (PGP) in increasing the bi-directional transport capacity of the zygote immediately following fertilisation. We posit that the activity of membrane bound PGP counters the influx of genotoxic agents, shielding the embryonic pronuclei from the induction of DNA damage. Excitingly, we also demonstrate that the preservation of the maternal genome, prior to fertilisation, is enhanced by an endogenous store of DNA repair proteins accumulated during oogenesis, providing the first evidence of an active DNA repair program in the post-ovulatory (MII) oocyte. Accordingly, we demonstrate a role for non-homologous end joining (NHEJ) as a repair platform for correcting damage of the maternal DNA prior to fertilisation. Having demonstrated that the oocyte and preimplantation embryo contain a sophisticated suite of defence strategies for the detection, repair or prevention of DNA damage, we hypothesized that the efficacy of these defences may be augmented by pro-survival factors. We therefore explored the capacity of C-peptide, a hormone implicated in the regulation of intracellular signalling pathways, to modulate oocyte and early embryo biology. Through this work, we observed a previously unappreciated abundance of C-peptide within the mouse ovary, oocyte and follicular fluid and uncovered a putative interaction between C-peptide and the DNA repair enzyme, breast cancer type 2 susceptibility protein (BRCA2) following oocyte activation. Collectively, these findings lend support to a novel role for C-peptide in the female germline and raise the prospect that C-peptide may exert direct physiological effects within the female reproductive system. Taken together, the findings reported in this thesis have enhanced our understanding of the maintenance of genetic stability in the female germline. Importantly, this collection of studies offers a molecular understanding of the endogenous capacity of the oocyte and preimplantation embryo to detect and subsequently respond to DNA damage and, in turn, identifies novel clinical targets to enhance oocyte competence in vitro and potentially improve assisted reproductive technologies.
- Subject
- oocytes; embryos; fertilisation; genotoxic; zygote; female infertility; pro-survival factors; C-peptide; insulin; BRCA2; DNA damage; DNA repair; non homologous end joining; quality control; permeability glycoprotein; DNA; double strand break; MII oocytes; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1395720
- Identifier
- uon:33931
- Rights
- Copyright 2019 Jacinta Martin
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 23 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 559 KB | Adobe Acrobat PDF | View Details Download |