Cardiovascular disease (CVD) is a major cause of death worldwide. The underlying cause of most CVD is atherosclerosis. Atherosclerosis is characterized by progressive plaque build-up in the... Show moreCardiovascular disease (CVD) is a major cause of death worldwide. The underlying cause of most CVD is atherosclerosis. Atherosclerosis is characterized by progressive plaque build-up in the arterial wall.Noncoding RNAs (ncRNAs) are RNAs that are not translated into protein. This thesis focuses on two types: microRNAs and small nucleolar RNAs (snoRNAs). MicroRNAs inhibit the production of proteins and act on multiple proteins simultaneously. In CVD, many different proteins are involved. Changing expression of one microRNA can therefore have a major impact.Numerous snoRNAs have been associated with diseases, including CVD. The function of half of the human C/D box snoRNAs, however, is unknown.The first aim of this thesis is to investigate inhibition of microRNA-494-3p in advanced atherosclerosis. The second aim is to elucidate the function of SNORD113-6, a snoRNA that is involved in CVD.The thesis shows that inhibition of microRNA-494-3p halts plaque progression and increases stability of advanced plaques. This reduces the risk of e.g. a myocardial infarction.Furthermore, SNORD113-6 influences the function of fibroblasts, scar cells, and thus plays a role in maintaining function of our blood vessels.These insights may open up new therapeutic possibilities in future treatment of CVD. Show less
To circumvent the dependency on prediction models, we developed a microRNA-screen-based assay to establish links between cellular phenotypes and microRNAs (miRNAs). To this end, a miRNA expression... Show moreTo circumvent the dependency on prediction models, we developed a microRNA-screen-based assay to establish links between cellular phenotypes and microRNAs (miRNAs). To this end, a miRNA expression library (miR-Lib) was built consisting of 300 annotated miRNAs and around 100 candidate miRNAs. These miRNA 'minigenes' were cloned from genomic DNA of human cells and inserted in a specially engineered retroviral expression vector. This vector, named miR-Vec, is a modified murine stem cell virus (pMSCV) vector, with the expression of the miRNA minigenes under the control of the CMV pol II promoter. The vast majority of naturally transcribed miRNA genes are known to be expressed by pol II promoters. In parallel with the miRNA library, a corresponding microarray was developed (miR-Array) containing DNA spots of the miRNA minigenes from the library. By combining the miRNA library and microarray tools, we designed and performed three distinct functional genetic approaches to identify cancerous microRNAs. Show less
