Atherosclerosis, the underlying cause of heart attack and stroke, is a major cause of death and suffering worldwide. The scavenger receptor BI (SR-BI) plays crucial roles in preventing atherosclerosis both by serving as a hepatic receptor for HDL cholesterol and by regulating macrophage cellular cholesterol homeostasis and survival in the arterial plaque. Recent studies have implicated SR-BI in cell survival by preventing apoptosis. Interestingly, our preliminary studies implicate a critical role for SR-BI in regulating autophagy, another key mechanism for promoting cell survival. Furthermore, our data suggest a novel role for SR-BI in mediating cell survival through the regulation of angiogenin, a RNase III enzyme that mediates tRNA cleavage to produce tRNA-derived smRNAs (tDRs), which promote cell survival through protein translation suppression and post- transcriptional repression of mRNA targets. Importantly, we have recently found that tDRs represent the most abundant class of smRNAs on HDL, as over 60% of smRNAs were aligned to tRNA loci in the reference genomes. Strikingly, our preliminary studies suggest that atherosclerotic vessels have increased levels of tDRs compared to healthy aortas.
In Specific Aim 1, we will examine the hypothesis that SR-BI antagonizes atherogenesis by controlling authophagic flux to limit macrophage death and foam cell formation.
In Specific Aim 2, we will examine the hypothesis that macrophage SR-BI promotes cell survival by specific tDR expression through regulation of angiogenin activity.
In Specific Aim 3, we will define the impact of SR-BI regulation of HDL-tDR communication in atherosclerosis. Furthermore, we will examine the impact of SR-BI deficiency on the signature of tDRs on HDL from humans with both common and rare loss-of function-variants of the SCARB1 gene. In addition, we will examine the impact of these human SCARB1 loss-of function variants on autophagy in macrophages. A better understanding of what processes lead macrophages to export tDRs to HDL and how this contributes to atherogenesis will likely lead to the discovery of new mechanisms underlying atherosclerosis and the identification of novel drug targets. Our ultimate goal is to leverage these novel roles of SR-BI in regulating autophagy, angiogenin and tRNA-derived small RNAs for therapeutic gain in the prevention and treatment of dyslipidemia and atherosclerosis.

Public Health Relevance

As the underlying cause of heart attack and stroke, atherosclerosis (plaque buildup in arteries) is a significant health and financial burden, and new approaches for prevention and treatment are needed. We will examine the novel hypothesis that the scavenger receptor BI (SR-BI) prevents atherosclerosis by regulating novel pathways for cell survival including a process called autophagy (self-preservation) and the generation of chemical messages called tRNA-derived smRNAs (tDRs) by the enzyme angiogenin. Our ultimate goal is to leverage these novel roles of SR-BI in regulating autophagy, angiogenin and tRNA-derived small RNAs to identify potential drug targets for nucleic acid-based therapies to treat and prevent atherosclerosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL127173-05
Application #
9618258
Study Section
Atherosclerosis and Inflammation of the Cardiovascular System Study Section (AICS)
Program Officer
Chen, Jue
Project Start
2016-01-01
Project End
2019-12-31
Budget Start
2019-01-01
Budget End
2019-12-31
Support Year
5
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Type
DUNS #
079917897
City
Nashville
State
TN
Country
United States
Zip Code
37232
Allen, Ryan M; Zhao, Shilin; Ramirez Solano, Marisol A et al. (2018) Bioinformatic analysis of endogenous and exogenous small RNAs on lipoproteins. J Extracell Vesicles 7:1506198
Mueller, Paul A; Zhu, Lin; Tavori, Hagai et al. (2018) Deletion of Macrophage Low-Density Lipoprotein Receptor-Related Protein 1 (LRP1) Accelerates Atherosclerosis Regression and Increases C-C Chemokine Receptor Type 7 (CCR7) Expression in Plaque Macrophages. Circulation 138:1850-1863
Li, Kang; Rodosthenous, Rodosthenis S; Kashanchi, Fatah et al. (2018) Advances, challenges, and opportunities in extracellular RNA biology: insights from the NIH exRNA Strategic Workshop. JCI Insight 3:
Zhu, Lin; Shi, Jeanne; Luu, Thao N et al. (2018) Hepatocyte estrogen receptor alpha mediates estrogen action to promote reverse cholesterol transport during Western-type diet feeding. Mol Metab 8:106-116
Babaev, Vladimir R; Ding, Lei; Zhang, Youmin et al. (2018) Loss of 2 Akt (Protein Kinase B) Isoforms in Hematopoietic Cells Diminished Monocyte and Macrophage Survival and Reduces Atherosclerosis in Ldl Receptor-Null Mice. Arterioscler Thromb Vasc Biol :ATVBAHA118312206
Babaev, Vladimir R; Huang, Jiansheng; Ding, Lei et al. (2018) Loss of Rictor in Monocyte/Macrophages Suppresses Their Proliferation and Viability Reducing Atherosclerosis in LDLR Null Mice. Front Immunol 9:215
Sedgeman, Leslie R; Beysen, Carine; Allen, Ryan M et al. (2018) Intestinal bile acid sequestration improves glucose control by stimulating hepatic miR-182-5p in type 2 diabetes. Am J Physiol Gastrointest Liver Physiol :
Sheng, Quanhu; Vickers, Kasey; Zhao, Shilin et al. (2017) Multi-perspective quality control of Illumina RNA sequencing data analysis. Brief Funct Genomics 16:194-204
Dean, E Danielle; Li, Mingyu; Prasad, Nripesh et al. (2017) Interrupted Glucagon Signaling Reveals Hepatic ? Cell Axis and Role for L-Glutamine in ? Cell Proliferation. Cell Metab 25:1362-1373.e5
Guo, Yan; Vickers, Kasey; Xiong, Yanhua et al. (2017) Comprehensive evaluation of extracellular small RNA isolation methods from serum in high throughput sequencing. BMC Genomics 18:50

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