Project description:miRNAs and other small RNAs have been found associated with high-density lipoproteins (HDL). The aim of this study was to investigate the miRNA signature on human HDL from 10 donors.
Project description:We quantified differential gene (mRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine which genes are regulated by native HDL compared to components of HDL and categorize data based on shared sets of genes and distinct sets of genes regulated by each component.
Project description:miRNAs are exported to high density lipoproteins (HDL). This study aimed to understand what miRNAs are exported from primary islets to HDL in vitro.
Project description:We quantified differential microRNA (miRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine whichmiRNAs are regulated by native HDL compared to components of HDL and categorize data based on shared sets of miRNAs and distinct sets of miRNAs regulated by each component.
Project description:Background: High density lipoprotein (HDL) protects the artery wall by removing cholesterol from lipid-laden macrophages. However, recent evidence suggests that it might also inhibit atherogenesis by combating inflammation. Methods and Results: To identify potential anti-inflammatory mechanisms, we challenged macrophages with lipopolysaccharide (LPS), an inflammatory microbial ligand for Toll-like receptor 4 (TLR4). HDL inhibited the expression of 33% (301 of 911) of the genes normally induced by LPS, microarray analysis revealed. One of its major targets was the type I interferon response pathway, a family of potent viral immunoregulators controlled by TLR4 and the TRAM/TRIF signaling pathway. Unexpectedly, HDL’s ability to inhibit gene expression was independent of cellular cholesterol stores. Moreover, it was unaffected by downregulation of two ATP-binding cassette transporters, ABCA1 and ABCG1, that promote cholesterol efflux. To examine the pathway’s potential in vivo relevance, we used mice deficient in apolipoprotein (apo) A-I, HDL’s major protein. After infection with Salmonella (a Gram-negative bacterium that expresses LPS), apoA-I–deficient mice had 6-fold higher plasma levels of interferon-beta-a key regulator of the type I interferon response than did wild-type mice. Conclusions: HDL inhibits a subset of LPS-stimulated macrophage genes that regulate the type I interferon response, and its action is independent of sterol metabolism. These findings raise the possibility that regulation of macrophage genes by HDL might link innate immunity and cardioprotection. 12 arrays, 3 experimental groups, mMncN (no treatment), mMncL (LPS treated, exposed for 4 h to serum-free medium or serum-free medium supplemented with 100 ng/mL of LPS), and mMwtL (HDL treated, Macrophages were treated for 4 h with serum-free medium or serum-free medium supplemented with 50 mg/mL of HDL, washed twice with PBS).
Project description:Specific mutations in Apolipoprotein A-I (ApoA-I) of high-density lipoprotein (HDL) are responsible for a late-onset systemic amyloidosis. Carriers do not exhibit increased cardiovascular disease risk despite reduced levels of ApoA-I/ HDL-cholesterol. To explain this paradox, we show that the HDL particle profile of L75P and L174S patients presents a higher relative abundance of the 8.4 nm vs 9.6 nm particles, and that serum from patients, as well as reconstituted 8.4 and 9.6 nm HDL particles (rHDL), possess increased capacity to catalyze cholesterol efflux from macrophages. Synchrotron radiation circular dichroism and hydrogen-deuterium exchange revealed that the variants in 8.4 nm rHDL have altered secondary structure composition and display a more flexible binding to lipids compared to their native counterpart. The reduced HDL-cholesterol levels of patients carrying ApoA-I amyloidogenic variants are thus balanced by higher proportion of small, dense HDL particles and better cholesterol efflux due to altered, region-specific protein structure dynamics.
Project description:The aim of this study was to identify HDL and apoE-regulated genes in human placental endothelial cells (HPEC), which are exposed to fetal HDL. HPECs extracted from 5 human placentas were cultivated and treated for 16 h with 15ug/ml fetal HDL, 15ug/ml reconstituted HDL (rHDL), or endothelial basal medium (EBM) as vehicle control. Gene expression analysis from these 3 conditions (5 biological replicates) using 15 Applied Biosystems Human Whole Genome Survey V2.0 Microarrays was perfomed and significantly differentially expressed genes between two different groups (HDL vs control or rHDL vs control) were identified.
Project description:Nuclear proteins bind chromatin to execute and regulate genome-templated processes. While structural and biochemical studies of individual nucleosome interactions have suggested that an acidic patch on the nucleosome disk surface may be a common site for recruitment to chromatin, the pervasiveness of acidic patch binding and whether other nucleosome surface binding hot-spots exist remains unclear. Here, we use nucleosome affinity proteomics with a library of nucleosomes that collectively disrupts all exposed histone surfaces to establish the universal principles of nucleosome binding. We find that the acidic patch and two adjacent surfaces are the primary hot-spots for nucleosome disk binding and are critical for the majority of nucleosome-protein interactions. In contrast, nearly half of the nucleosome disk surface participates only minimally in protein binding. In addition to establishing the fundamental principles of chromatin binding, our screen defines nucleosome surface requirements of nearly 300 nucleosome interacting proteins implicated in diverse nuclear processes including transcription, DNA damage repair, cell cycle regulation, and nuclear architecture. Building from our screen, we demonstrate that the Anaphase-Promoting Complex/Cyclosome directly binds the acidic patch and elucidate a redundant charge-based mechanism of acidic patch binding by nuclear pore protein ELYS. Overall, our interactome screen illuminates a highly competitive nucleosome binding hub for chromatin-targeted activities and curates a list of nucleosome interacting proteins that will enable mechanistic exploration of many unexpected chromatin-templated nuclear processes.