The human genome encodes thousands of long noncoding RNAs (lncRNAs), the majority of which are poorly conserved and uncharacterized. Here we identify a primate-specific lncRNA (CHROME), which is... Show moreThe human genome encodes thousands of long noncoding RNAs (lncRNAs), the majority of which are poorly conserved and uncharacterized. Here we identify a primate-specific lncRNA (CHROME), which is elevated in the plasma and atherosclerotic plaques of individuals with coronary artery disease, and regulates cellular and systemic cholesterol homeostasis. Expression of the lncRNA CHROME is influenced by dietary and cellular cholesterol through the sterol-activated liver X receptor transcription factors, which control genes that mediate responses to cholesterol overload. Using gain- and loss-of-function approaches, we show that CHROME promotes cholesterol efflux and high-density lipoprotein (HDL) biogenesis by curbing the actions of a set of functionally related microRNAs that repress genes in those pathways. CHROME knockdown in human hepatocytes and macrophages increases the levels of miR-27b, miR-33a, miR-33b and miR-128, thereby reducing the expression of their overlapping target gene networks and associated biological functions. In particular, cells that lack CHROME show reduced expression of ABCA1, which regulates cholesterol efflux and nascent HDL particle formation. Collectively, our findings identify CHROME as a central component of the noncoding RNA circuitry that controls cholesterol homeostasis in humans. Show less
Bijkerk, R.; Trimpert, C.; Solingen, C. van; Bruin, R.G. de; Florijn, B.W.; Kooijman, S.; ... ; Zonneveld, A.J. van 2018
This thesis details our studies assessing the role of the endothelial-enriched miRNA-126 in the regulation of vascular homeostasis. In Chapter 2 the current insight in the role of miRNA-126 in... Show moreThis thesis details our studies assessing the role of the endothelial-enriched miRNA-126 in the regulation of vascular homeostasis. In Chapter 2 the current insight in the role of miRNA-126 in vascular homeostasis is reviewed. Chapter 3 focuses on the role of miRNA-126 in ischemia induced angiogenesis, followed by Chapter 4 which describes the potential role of miRNA-126 the mobilization of vasculogenic progenitor cells upon ischemia. Both chapters utilize antagomir-technology to specifically silence miRNA-126 in vivo. This approach to silence miRNA-126 was also used in Chapter 5 to elucidate the regulatory role of miRNA-126 in vascular cell adhesion molecule-1 expression in the kidney vasculature. Chapter 6 details our findings that circulating miRNA-126 in the periphery is not exclusively derived from endothelial cells but can also originate from platelets. Consequently, the use of aspirin has to be taken into account when relating circulating miRNA-126 levels to the progression of cardiovascular disease. Chapter 7 demonstrates that the angiogenic potential of miRNA-126 as described in Chapter 3 might reach beyond the presence of this pro-angiogenic miRNA in endothelium, but that neovascularization can also be supported by miRNA-126 expressed in circulating cells. Finally, Chapter 8 provides a summary of research presented in this thesis, presents the major conclusions that could be drawn and further discusses the role of miRNA-126 in vascular homeostasis. Show less
Asgeirsdottir, S.A.; Solingen, C. van; Kurniati, N.F.; Zwiers, P.J.; Heeringa, P.; Meurs, M. van; ... ; Molema, G. 2012
AIMS MicroRNA-126 (miR-126), which is enriched in endothelial cells, plays a role in angiogenesis. Based on the seed sequence, miR-126 can also be predicted to regulate vasculogenesis by modulating... Show moreAIMS MicroRNA-126 (miR-126), which is enriched in endothelial cells, plays a role in angiogenesis. Based on the seed sequence, miR-126 can also be predicted to regulate vasculogenesis by modulating the endothelial expression of stromal cell-derived factor-1 (SDF-1). METHODS AND RESULTS Using miR-reporter constructs, we first validated that miR-126 inhibits SDF-1 expression in endothelial cells in vitro. Next, we investigated the potential relevance of this observation with respect to the mobilization of progenitor cells. For this, we studied the migration of human CD34+ progenitor cells towards chemotactic factors present in endothelial cell-conditioned medium. Antagomir-induced silencing of miR-126 elevated SDF-1 expression by human umbilical vein endothelial cells and enhanced migration of the CD34+ cells. In a murine model of hind limb ischaemia, a striking increase in the number of circulating Sca-1(+)/Lin(-) progenitor cells in antagomir-126-treated mice was observed when compared with scramblemir-treated controls. Immunohistochemical staining of capillaries in the post-ischaemic gastrocnemius muscle of miR-126-silenced mice revealed elevated SDF-1 expressing CD31-positive capillaries, whereas a mobilizing effect of miR-126 inhibition was not detected in healthy control animals. CONCLUSION miR-126 can regulate the expression of SDF-1 in endothelial cells. In the context of an ischaemic event, systemic silencing of miR-126 leads to the mobilization of Sca-1(+)/Lin(-) progenitor cells into the peripheral circulation, potentially in response to elevated SDF-1 expression by endothelial cells present in the ischaemic tissue. Show less
Solingen, C. van; Monge, M.; Vries, D.K. de; Seghers, L.; Vries, M.R. de; Bijkerk, R.; ... ; Zonneveld, A.J. van 2010
