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Title: Functional roles of microRNA-214 in modulating smooth muscle cell functions and neointima formation
Author: Afzal, T. A.
ISNI:       0000 0004 7962 4990
Awarding Body: Queen Mary, University of London
Current Institution: Queen Mary, University of London
Date of Award: 2019
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Vascular Smooth Muscle cells (VSMCs) have very important role in pathogenesis of atherosclerosis and neointima formation. VSMCs phenotype switching and resultant increase in migration and proliferation under the influence of certain pro-inflammatory mediators is widely addressed but further research aiming at identifying the molecular mechanisms governing these changes is still required. Since the identification of microRNA (miR) as potent post transcriptional gene regulators, several studies have revealed their role in atherosclerosis and neointima formation. miR-214 was previously considered as oncogene but later studies have pointed at its role in tumourogenesis inhibition. Researchers have postulated a divergent role of miR-214 in cardiovascular diseases ranging from beneficial and cardiomyocyte protector to damaging by causing cardiac hypertrophy but its role in VSMC functional regulation is still unclear. In our study, we analysed its role in regulating VSMC function (migration and proliferation) during neointima formation. By applying loss of function and gain of function experiments, we identified that miR-214 has an inverse relationship to VSMCs functions. Overexpressing miR-214 resulted in reduced VSMC migration and proliferation and vice versa. Proteomics analysis and algorithmic computation models revealed an interesting relationship between miR-214 and Nck associated protein 1 (NCKAP1), a major components of WAVE complex and involved in regulating actin polymerization and lamellipodia formation. In our study on VSMCs, we have identified NCKAP1 as the functional target gene of miR-214 in regulating VSMC functions in atherosclerosis and neointima formation. By implementing gene and protein biochemical assays including proteomic analysis, we have provided compelling evidence to support a regulatory role for miR-214/NCKAP1 in VSMCs migration and motility. NCKAP1 knockdown in VSMCs recapitulates the inhibitory effects of miR-214 over-expression on actin plymerization, cell migration and proliferation. Furthermore, cotransfection experiments also revealed that inhibition of NCKAP1 is required for miR-214 medited lamellipodia formation, cell motility and growth. Importantly, locally enforced expression of miR-214 to the injured vessels significantly reduced NCKAP1 expression levels, inhibited VSMC proliferation and prevented neointima hyperplasia after injury. Our data is in line with the aforementioned role of NCKAP1 as imperative and constitutive component of WAVE complex, leading to lamellipodia formation and actin filament polymerization. We have extended NCKAP1's role in VSMC mobility and proliferation under the effect of pro-inflammatory mediators and under conditions of vascular injury. Our study has uncovered an important relationship between miR-214 and its target gene NCKAP1 in modulating VSMC functions and their effect on neointima hyperplasia. Our findings suggest that miR-214 represents a potentioal therapeutic target for vascular disease.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Vascular Smooth Muscle cells ; neointima formation ; microRNA ; vascular disease.