Views
8 months ago

2017 Cardiovascular Research Day Abstract Book

73 A specific rotamer of

73 A specific rotamer of apolipoprotein A-I enables Lecithin-cholesterol acyl transferase activation by discoidal HDL Allison L. Cooke 1 • Jamie C. Morris 1 • John T. Melchior, PhD 1 • Rong Huang, PhD 1 • W. Gray Jerome, PhD 2 • Scott E Street 1 • W. Sean Davidson, PhD 1 1Pathology, University of Cincinnati • 2 Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center Graduate Student Investigating the structure of apolipoprotein (apo)A-I, the primary protein component of high density lipoprotein (HDL), is important for understanding how HDL interacts with lipid-modifying proteins to mediate its cardioprotective functions in plasma. HDL lipid discs contain two molecules of apoA-I arranged in an antiparallel, stacked ring-structure. ApoA-I is composed of 10 tandem, amphipathic, alpha-helical repeats that encapsulate lipid for plasma transport on the hydrophobic face of the ring-structure, and allows HDL to interact with modifying proteins on the hydrophilic face. For example, lecithin-cholesterol acyl transferase (LCAT) is a critical lipoprotein-associated enzyme that converts cholesterol to cholesterol ester for transport out of peripheral cells. It was hypothesized that changing the orientation of apoA-I on HDL discs can modulate LCAT reactivity. To test this, site-directed cysteine-point mutagenesis was used to generate different orientations (rotamers) of apoA-I on HDL discs of similar size and composition: K133C- helix 5 of one apoA-I molecule adjacent to helix 5 of its antiparallel partner (5/5 rotamer), K206C- helix 5 adjacent to helix 2 (5/2 rotamer), and K195C-helix 5 adjacent to helix 1 (5/1 rotamer). Initially, an LCAT activation assay revealed LCAT had significantly increased reactivity to discs with the 5/5 rotamer relative to wild-type or the other rotamers (p

74 Circulating Bacterial Small RNA Bound to LDL Induce Inflammatory Activation of Macrophages Ryan Allen, PhD 1 • Shilin Zhao, PhD 2 • Marisol Ramirez, MS 1 • Bradley Richmond, MD, PhD 3 • Timothy Blackwell, MD 3 • Quanhu Sheng, PhD 2 • Kasey Vickers, PhD 1 1Cardiovascular Medicine, Vanderbilt University Medical Center • 2 Center for Quantitative Sciences, Vanderbilt University Medical Center • 3 Allergy and Inflammation, Vanderbilt University Medical Center Postdoc Chronic, sub-acute inflammation is an active component of many human diseases of diverse etiology, characterized by sustained recruitment and activation of macrophages. Macrophages are phagocytic, myeloid-derived cells that are resident in nearly every tissue to provide innate defense against invasive pathogens. Upon injury, macrophages respond to remove damaged cells and cell debris and facilitate tissue repair. However, in disease, prolonged activation of macrophages promotes tissue remodeling, often to the detriment of tissue function. This is classically observed in the development of atherosclerosis, in which monocytes infiltrate the artery wall, differentiate to macrophages, and phagocytize LDL to become cholesterol-engorged “foam cells”, which rapidly develop a pro-inflammatory phenotype that contributes to further cardiovascular disease. Our lab previously reported that high-density lipoproteins (HDL) traffic miRNAs between cells as part of intercellular gene-regulation networks that we proposed could mediate anti-inflammatory properties of HDL. Although low-density lipoproteins (LDL) have also been reported to traffic miRNA, more recent data from small-RNA sequencing (sRNA-SEQ) indicates that LDL-associated sRNA are primarily exogenous, with most sRNA fragments originating from bacteria. Most interestingly, taxonomic analysis of bacteria contributing sRNA to the LDL pool revealed a profile distinct from any characterized profile of the comprehensive human microbiome. Additionally, antibiotic mediated ablation of the gut microbiome failed to disrupt lipoprotein-sRNA pools of mice, suggesting that bacterial sRNA fragments are not linked to the gut microbiome. However, manipulation of housing conditions was capable of inducing stark changes in the landscape of bacterial sRNA bound to lipoproteins of mice, indicative of a potential role for the environment in shaping the lipoprotein-sRNA fingerprint. In support of this, we characterized the lipoprotein-sRNA profiles of wild-type and polymeric IgA receptor deficient (Pigr-/-) mice, a model of compromised airway mucosal immunity, and found reduced abundance of bacterial sRNA fragments, most notably of Proteobacteria and Firmicutes. Although many potential functions remain to be explored, we hypothesized that exogenous sRNA associated with LDL may influence the inflammatory potential of LDL upon uptake by artery-wall macrophages by activation of endosomal, nucleic acidsensing toll-like receptors (TLR), which are highly expressed in macrophages and facilitate innate immunity. To test this hypothesis, we treated primary mouse macrophages and PMA-stimulated THP1 cells with physiologically relevant concentrations of fresh, native LDL (nLDL) and observed induction of pro-inflammatory cytokine expression. Strikingly, partial silencing of nucleic acidsensing TLRs blunted this nLDL induced activation of pro-inflammatory gene expression. Conversely, treatment of human hepatoma cells, which express low levels of exogenous RNAsensing TLRs, with nLDL failed to induce pro-inflammatory cytokine expression. Taken together, our data identify a novel, non-lipid cargo of LDL that is capable of modulating inflammatory gene expression in macrophages and may contribute to the pathogenesis of atherosclerosis, and many other metabolic diseases. 90

Assessment of Tobacco Smoke-Mediated Atherosclerosis in Mouse ...
Research Days 2013 Abstract Book - Office of the Vice President for ...
Abstract Book Research Day 2013.pdf - University of Minnesota ...
Research Day Book 2013 - College of Medicine - Florida Atlantic ...
2010 Abstracts - Radiation Research Society
Abstract Booklet - University of Ottawa Heart Institute
Book of Abstracts - Australian Centre for Economic Research on ...
book of abstracts 11th annual research half day may 12, 2010 ...
research day - University of Toronto Department of Obstetrics and ...
Abstract Book - Pathology and Laboratory Medicine - University of ...
Abstracts - Society of Cardiovascular Anesthesiologists
Abstracts - Interactive CardioVascular and Thoracic Surgery
Abstracts for The European Society for Cardiovascular Surgery 53rd ...
CARDIOVASCULAR DISEASE IN WOMEN - Epib.nl
PATHOLOGY OF THE CARDIOVASCULAR SYSTEM Dr: Khitam Dr ...
Oral Presentations - Arteriosclerosis, Thrombosis, and Vascular ...
Reverse cholesterol transport and cholesterol efflux in atherosclerosis
Technologist Abstracts - Society of Cardiovascular Magnetic ...
Conditional Risk Factors for Atherosclerosis - Mayo Medical ...
The interplay of inflammation and cardiovascular disease in ...
Book of Abstracts - Oxygen Club of California
Cardiovascular Lab Indicators - Anaturalhealingcenter.com
Cardiovascular Disease: C-Reactive Protein - Thorne Research
Book of Abstracts - Oxygen Club of California