Project 3 (P3). Noncanonical activities of a tRNA synthetase in metabolism and atherosclerosis Paul L. Fox, Ph.D., Project Leader Project Summary/Abstract The long-term goal of Project 3 is to understand the noncanonical function of an extraordinary tRNA synthetase, the Glu-Pro tRNA synthetase or EPRS, in diet-induced obesity and consequent cardiovascular disease, particularly atherosclerosis. The recent explosive epidemic of obesity, insulin resistance, and cardiovascular disease has begun an unprecedented decline in the health-span of adults in the U.S., and likewise threatens an equally unprecedented economic burden. In 1942, James Neel suggested a possible rationale for the genetic selection of genes causing these pathologies. He posited that metabolic pathways were naturally selected to efficiently store fat and carbohydrate during periods of food scarcity; however, the same genes and pathways are detrimental during periods of plentiful, calorie-rich food supply as in the Western world today. A kinase cascade involving the mammalian target of rapamycin (mTORC1) and ribosomal protein S6 kinase-1 (S6K1) is implicated as a key metabolic pathway regulating food utilization, and is conserved from Drosophila to humans. Despite intense study, the key downstream effector(s) of mTORC1-S6K1, and consequent cell mechanisms that regulate metabolism remains unknown. During the previous Project period, we made fundamental in vitro and in vivo discoveries that revealed phosphorylated EPRS as a key downstream effector of mTORC1-S6K1, regulating post-transcriptional, inflammation-related pathways in macrophages and metabolic pathways in adipocytes. Inflammatory macrophages permeate the more abundant adipocytes in adipose tissue of obese subjects, and EPRS phosphorylation in both cell types by S6K1 might functionally couple these cells, and contribute importantly to obesity-associated cardiovascular disease. To test the role of phospho-EPRS in these processes we have generated genetically-modified EPRS phospho-deficient and phospho-mimetic knock-in mice. Preliminary studies show that phospho-deficient EPRS mice phenocopy S6K1-null mice, e.g., small size and low fat mass, and will permit rigorous investigation of the role of EPRS in mTORC1-S6K1-driven mechanisms in vivo. We propose to test the following hypothesis: Phospho-EPRS is a critical effector of the mTORC1-S6K1 signaling pathway in both adipocytes and macrophages, and contributes importantly to diet- induced obesity and atherosclerosis. Our discovery that EPRS is a key mTORC1-S6K1 effector activated by agonists of both inflammation and metabolism provides a molecular link between these processes. We anticipate our studies will reveal new mechanisms underlying obesity and atherosclerosis, and can provide novel therapeutic targets for treatment of these related disorders.

Public Health Relevance

Project 3 (P3). Project Narrative The United States is facing an accelerating epidemic of diet-induced obesity, and its associated pathological consequences, including diabetes and atherosclerosis. We have discovered a new connection between an agent previously known to drive dietary obesity, namely mTOR, with a protein not previously associated with this process, i.e., EPRS. We will study the mechanisms by which EPRS exacerbates diet-induced obesity in cells and in mice. These studies can provide novel approaches and therapeutic targets for future treatments.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL029582-32
Application #
8960943
Study Section
Special Emphasis Panel (ZHL1)
Project Start
Project End
Budget Start
2015-11-01
Budget End
2016-10-31
Support Year
32
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Cleveland Clinic Lerner
Department
Type
DUNS #
135781701
City
Cleveland
State
OH
Country
United States
Zip Code
44195
Herjan, Tomasz; Hong, Lingzi; Bubenik, Jodi et al. (2018) IL-17-receptor-associated adaptor Act1 directly stabilizes mRNAs to mediate IL-17 inflammatory signaling. Nat Immunol 19:354-365
Robinet, Peggy; Milewicz, Dianna M; Cassis, Lisa A et al. (2018) Consideration of Sex Differences in Design and Reporting of Experimental Arterial Pathology Studies-Statement From ATVB Council. Arterioscler Thromb Vasc Biol 38:292-303
Zhang, Cun-Jin; Wang, Chenhui; Jiang, Meiling et al. (2018) Act1 is a negative regulator in T and B cells via direct inhibition of STAT3. Nat Commun 9:2745
Han, Juying; Enyindah-Asonye, Gospel; Lin, Feng et al. (2018) CD6 expression has no effect on atherosclerosis in apolipoprotein E-deficient mice. BMC Res Notes 11:229
Sarvestani, Samaneh K; Signs, Steven A; Lefebvre, Veronique et al. (2018) Cancer-predicting transcriptomic and epigenetic signatures revealed for ulcerative colitis in patient-derived epithelial organoids. Oncotarget 9:28717-28730
Arif, Abul; Yao, Peng; Terenzi, Fulvia et al. (2018) The GAIT translational control system. Wiley Interdiscip Rev RNA 9:
Hai, Qimin; Ritchey, Brian; Robinet, Peggy et al. (2018) Quantitative Trait Locus Mapping of Macrophage Cholesterol Metabolism and CRISPR/Cas9 Editing Implicate an ACAT1 Truncation as a Causal Modifier Variant. Arterioscler Thromb Vasc Biol 38:83-91
Eswarappa, Sandeep M; Potdar, Alka A; Sahoo, Sarthak et al. (2018) Metabolic origin of the fused aminoacyl-tRNA synthetase, glutamyl-prolyl-tRNA synthetase. J Biol Chem 293:19148-19156
Halawani, Dalia; Gogonea, Valentin; DiDonato, Joseph A et al. (2018) Structural control of caspase-generated glutamyl-tRNA synthetase by appended noncatalytic WHEP domains. J Biol Chem 293:8843-8860
Zepp, Jarod A; Zhao, Junjie; Liu, Caini et al. (2017) IL-17A-Induced PLET1 Expression Contributes to Tissue Repair and Colon Tumorigenesis. J Immunol 199:3849-3857

Showing the most recent 10 out of 276 publications