Projects Area B: Nucleic acids and lipid mediators
Circular RNAs (circRNAs) are a novel class of RNAs. In preliminary work, we found that numerous circRNAs are down-regulated in atherosclerotic lesions, suggesting atheroprotective properties. We will study mechanisms of identified circRNAs in cell functions of atherogenesis in vitro (Aim 1) and investigate their molecular effector mechanisms using bioinformatics and molecular biology (Aim 2). CircRNAs will be applied in vivo in mouse models of atherosclerosis (Aim 3) and will be studied to predict human atherosclerosis in different vascular beds (Aim 4). Since circRNAs are stable against degradation, they constitute promising novel diagnostic and therapeutic approaches.
Several loci which harbor genes of the NO-cGMP-signaling pathway have been genome-wide significantly associated with coronary artery disease (CAD) and myocardial infarction. While the molecular mechanisms affecting the GUCY1A3 locus have been resolved this remains unclear for variants at the loci which encode endothelial nitric oxide synthase (NOS3) and phosphodiesterase 5A (PDE5A). Here, we aim to specifically investigate the link between genotype and phenotype at the NOS3 locus (Aim 1), to elucidate the role of PDE5A in modulating CAD risk (Aim 2), and to evaluate strategies for therapeutic targeting the pathway in in vitro and in vivo models (Aim 3).
Our previous work established a pro-inflammatory and pro-atherogenic role of HDAC9 and identified an activating effect of HDAC9 on NF-κB signaling. We now aim to expand on these results by addressing the following: (Aim 1) examine effects of HDAC9 on chromatin accessibility, the transcriptome, as well as the cellular proteome and secretome using ATAC-seq, RNA-seq, and LC-MS/MS; (Aim 2) investigate HDAC9-related alterations in NF-κB signaling under pro-inflammatory conditions; (Aim 3) study cell-specific effects of HDAC9 on atheroprogression and neointima formation using Hdac9flox/flox and atherogenic deleter mice.
topB04: miRNA-regulated energy metabolism in macrophage-derived foam cells
Excessive lipid storage in macrophages is regulated by miRNAs and results in the formation of foam cells, which eventually undergo apoptosis and contribute decisively to the necrotic core in atherosclerotic lesions. We hypothesize that miRNAs control foam cell formation by regulating the metabolism of triglycerides. Thus, we will study whether Dicer limits foam cell formation by increasing fatty acid oxidation (Aim 1), investigate the mechanism by which miR-147 regulates energy metabolism in foam cells (Aim 2), and test whether let-7b expression in macrophages reduces foam cell formation and atherosclerosis by enhancing oxidative phosphorylation (Aim 3).
Activation of SMCs and macrophages is important in advanced atherosclerosis. A screen of miRNAs embedded within neutrophil extracellular traps (NETs) revealed the targeted deposition of several miRNAs with relevance to macrophage and SMC activity. To dissect the importance of neutrophil miRNAs, we will study the intrinsic impact of these on neutrophil functionality (Aim 1) and investigate how NET-bound miRNAs alter the functionality of macrophages and SMC (Aim 2). Finally, we will study the contribution of neutrophil-borne miRNAs to atheroprogression and use intervention approaches to abrogate deregulated processes initiated by neutrophil miRNAs (Aim 3).
Innate immune cells contribute to atherothrombosis. Yet, how aging impacts on the pro- and antithrombotic action of innate immune cells remains incompletely understood. We therefore plan to identify and compare the inflammatory pathways that support and suppress atherothrombosis in young and aged atherosclerotic mice (Aim 1). We will dissect the role of immune cell pathways controlled by mTORC1 activity and autophagy induction, processes that altogether affect aging (Aim 2). Finally, we will investigate how necrotic core components are sensed and engulfed by recruited immune cells during atherothrombosis in young and aged mice (Aim 3).top
B07: Mechanisms of microbiota-mediated alteration in atherogenesis
Our data provide evidence that the inflammasome members Nlrp3 and Nlrp6 promote opposing functions in atherogenesis. We found that NLRP3 serves as “early sensor” for high fat western diet (WD) and initiates epigenetic changes and advanced onset of atherosclerotic disease, whereas NLRP6 protects the host, possibly by maintaining intestinal immune homeostasis. Here, we aim at identifying active NLRP3 and NLRP6 inflammasomes during WD (Aim 1), metabolic evaluation of the gut-liver-atheroma axis in a hypercholesteremic environment (Aim 2), and deciphering NLRP6-based influences on the epigenetic landscape in the early onset of atherosclerotic disease (Aim 3).
In view of potential therapeutic application of peripherally active cannabinoid receptor CB1 antagonists, we aim to clarify cell-specific effects of vascular and hematopoietic CB1 in atherosclerosis. So far, our data suggest opposing roles of endothelial and myeloid CB1 in atherosclerotic plaque formation, with surprising effects on metabolic parameters in absence of endothelial CB1. In the following, we aim to address how endothelial CB1 promotes atheroprogression (Aim 1) and affects metabolic parameters (Aim 2). In addition, we will investigate how macrophage CB1 signaling affects atherosclerotic plaque stability (Aim 3).