- Title
- The role of cell cycle regulation in granulosa cells during mouse ovarian development
- Creator
- Frost, Emily Rose
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Infertility is a public health issue affecting up to 15% of couples globally, with 50% of all infertility attributed to female factors. Female infertility can be caused by abnormalities in the fallopian tubes, uterus, ovaries and endocrine system. Infertility also occurs with increasing maternal age, as the reserve of oocytes is depleted in the ovary and menopause is reached. Thus, women have a finite reproductive lifespan in which to conceive a child, determined at least in part by the number and quality of oocytes within the ovary. Oocytes are stored in primordial follicles, which remain dormant until selected for activation. While many molecular pathways have been implicated, the complex mechanisms that coordinate primordial follicle activation remain unclear. The Cip/Kip family of cyclin-dependent kinase inhibitors are well characterised for their role in preventing cell cycle progression. This protein family consisting of p21Cip1, p27kip1 and p57kip2 canonically act by binding to CDKs and cyclins to prevent cell cycle resumption. However, recent studies demonstrate that p21Cip1, p27kip1 and p57kip2 also regulate other cellular processes including apoptosis, cell migration, cell fate decisions, and importantly transcriptional regulation. In particular, these proteins are expressed in the mouse gonad but the transcriptional role that these proteins play in the growth and maturation of the ovary remains unknown. The purpose of this thesis was to characterise the transcriptomic signature of pregranulosa cells before, during and after primordial follicle activation. I developed a novel method of mouse ovarian dissociation suitable for single cell RNA-sequencing and generated a transcriptomic dataset of the mouse ovary at three developmental stages. The heterogeneity observed in the gene expression signatures of granulosa cells suggests that the regulation of key genes controls and facilitates primordial follicle activation. One of the genes identified in pregranulosa cells was Cdkn1b, the gene name for p27kip1. I established that p27kip1 is an essential moderator of primordial follicle activation and loss of p27kip1 changes the transcriptome of the somatic cells and disrupts primordial follicle activation. I also generated a genetically altered mouse model deficient in FOXL2 and p27kip1 expression which provides evidence that FOXL2 maintains the expression of p27kip1 during primordial follicle formation. Taken together, the findings of this thesis contribute to our understanding of the transcriptional profile of pregranulosa cells during the window of primordial follicle activation. Importantly, these studies have provided extensive datasets to interrogate the mechanisms regulating follicle activation in all cells in the perinatal mouse ovary. The integration of these datasets illustrates an alternate way to study follicle activation, by combining wild-type data with infertility models to understand how this process can be changed. By an increased understanding of how this process happens in mice, this thesis provides the field with more knowledge about the ovarian reserve is established and conserved, which holds the potential to improve the diagnosis and treatments available for women diagnosed with POI and other infertility conditions, including infertility as a result of chemotherapy.
- Subject
- ovarian development; infertility; single-cell RNA sequencing; primordial follicles; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1468513
- Identifier
- uon:48058
- Rights
- Copyright 2021 Emily Rose Frost
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 25 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 177 KB | Adobe Acrobat PDF | View Details Download |