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Characterisation of oestrogen-responsive microRNAs modulating tissue factor and factor VIII: Potential novel biomarkers of thrombosis

Tian, Jiayin (2021) Characterisation of oestrogen-responsive microRNAs modulating tissue factor and factor VIII: Potential novel biomarkers of thrombosis. PhD thesis, Murdoch University.

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Abstract

Females with high oestrogen levels are more susceptible to develop thrombosis. Increased oestrogen levels lead to an induction of several pro-coagulant factors, including tissue factor and factor VIII, and a significant reduction of protein S (anti-coagulant factor), which engenders a hypercoagulable state to provoke venous thromboembolism (VTE). There is no specific cure for oestrogen-mediated VTE. This PhD project proposes that oestrogen may indirectly regulate coagulation factors via oestrogen-responsive microRNAs (miRs), which are small post-transcriptional regulators. miR-365a-3p and miR-548aa have previously been shown to be down-regulated by oestrogen, and contained a direct binding site on tissue factor and factor VIII mRNA, respectively. The overall aim is to investigate the role of these miRs on their coagulation factor targets, in vitro and in the circulation, and to evaluate the potential of using selected miRs as blood biomarkers of oestrogen-related VTE.

Overexpression of miR-365a-3p in vitro resulted in significant reductions of tissue factor mRNA (~49 %) and protein expression (~27 %), respectively. The miR-365a-3p-mediated tissue factor downregulation further attenuated tissue factor-initiated factor X activity (by 20 %) and thrombin generation (3.0-7.0-fold change of assay parameters, P<0.05). Exogenous expression of miR-548aa confirmed factor VIII mRNA expression was significantly decreased (27 %, P<0.05). Following the miR expression and coagulation factors profile screen, high oestrogen cohorts (hormone-based contraceptive users and pregnant donors) demonstrated a 2.4-fold (P<0.05) and 1.5-fold increase of miR-365a-3p expression, compared to controls. These changes were both correlated with a 1.5-fold (P<0.05 for hormone-based contraceptive group) elevation of tissue factor activity. Women with high oestrogen levels showed a 1.3-2.0-fold induction of miR-548aa, particularly for pregnant participants at their third trimester (P<0.05), and a relative increase of factor VIII activity (1.2-1.5-fold, P<0.001 for third trimester pregnancy).

This PhD thesis is the first to report miR-365a-3p as a potent regulator of tissue factor, and to investigate the haemostatic role of miR-548aa in regulating factor VIII mRNA. In the presence of high oestrogen levels, a positive correlation between levels of miRs and target coagulation factors in circulation was observed, suggesting miR response to oestrogen may vary between cells and circulating blood. Taken together, these novel findings strongly support the rationale for an oestrogen-mediated miR regulatory network in haemostasis that may be essential for the pathophysiology of VTE. It also highlights the importance for additional research on miR and its regulatory roles in hormone-related VTE. Further investigation of hormone mediated miR regulation in thrombosis can improve our understanding of disease pathogenesis, identify precise biomarkers, or develop molecular-targeted therapies, e.g., anti-miRs, to reduce the health-care cost of thrombosis and benefit current and future patients.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): Medical, Molecular and Forensic Sciences
United Nations SDGs: Goal 3: Good Health and Well-Being
Supervisor(s): Adams, Murray, Tiao, Jim and Baker, Ross
URI: http://researchrepository.murdoch.edu.au/id/eprint/61845
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