Establishing human diabetic vascular models and investigating the role of RNA binding proteins to treat diabetic vasculopathy

Abstract

Vascular diseases are major causes of disability and death in patients with diabetes mellitus. Despite the high morbidity, mortality and economic burden, the pathogenesis behind diabetic vascular dysfunction remains predominantly unclear, limiting treatment strategies. Although underlying mechanisms are poorly defined, it is clear that endothelial cell dysfunction plays a central role, thereby representing a potential therapeutic target. Due to the problems surrounding obtaining functional primary endothelial cells, induced pluripotent stem cell derived endothelial cells (iPS-ECs) have emerged as valuable research models. This thesis assesses the ability of diabetic derived iPS-ECs (dbiPS-ECs) to effectively recapitulate the disease phenotype. Sequencing and functional analysis revealed dbiPS-ECs to have reduced angiogenic capacity, mitochondrial dysfunction, impaired barrier function and increased reactive oxygen species (ROS) generation versus those from healthy donors; demonstrating dbiPS-ECs as clinically relevant models of diabetic vasculopathy that could help uncover pathogenic mechanisms and develop novel therapies. Previously the RNA Binding Protein QKI-7 was shown to be a critical mediator of vascular dysfunction in experimental diabetes, with knockdown in vivo significantly restoring blood flow and reperfusion in a diabetic hindlimb ischemia mouse model. Here further evaluation has revealed QKI-7 to promote the degradation of downstream homeostatic genes, COL4A2, JUN, TMEM184A and PPP1R15A in dbiPS-ECs resulting in impaired network formation, identifying four mediators of QKI-7 orchestrated angiogenic dysfunction and further highlighting QKI-7 as an attractive therapeutic target for diabetic vasculopathy. Connectivity mapping of QKI-7 gene signatures against FDA approved compounds was subsequently performed to identify drugs which may suppress its activity, with Simvastatin, Halcinonide and Retinoic Acid being found to have potential to target QKI-7 expression. In vitro studies in dbiPS-ECs confirmed the ability of each drug to suppress QKI-7 signalling and restore vascular function, quantified by network formation, barrier function and ROS production. Taken together, this thesis validates the use of dbiPS-ECs as disease models, provides a key insight into the signalling pathways underlying diabetic vasculopathy, particularly identifying QKI-7 as a central mediator of endothelial cell dysfunction and highlights downstream targets COL4A2, JUN, TMEM184A and PPP1R15A to be key regulators of vascular function. Importantly, this thesis indicates repurposing of FDA approved drugs to specifically target QKI-7 as a promising therapeutic strategy for this debilitating condition.

Thesis embargoed until 31st July 2026

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy & British Heart Foundation
Supervisor	Andriana Margariti (Supervisor) & David Grieve (Supervisor)