Stress-induced tRNA-derived small RNAs in cardiac fibrosis

Massachusetts General Hospital, Boston MA

Investigators

Abstract

PROJECT ABSTRACT Heart failure (HF) remains the leading cause of morbidity and mortality in the US, impacting approximately 6.2 million Americans. Cardiac fibrosis, resulting from disruptions in cardiac homeostasis and subsequent injury, stands as a major contributor to the detrimental remodeling of the heart that ultimately leads to HF. Therefore, identifying novel therapeutic pathways is crucial for advancing treatment options in the field. Recent studies have shown that under stress conditions, tRNAs can be processed by ribonucleases into smaller regulatory fragments known as tRNA-derived small RNAs (tDRs), which serve as an adaptive mechanism helping cells cope with stressors. Emerging evidence indicated that tDRs play critical roles in cellular stress response machineries during diverse biological processes. However, the regulatory functions of tDR in cardiac fibrosis remain largely unexplored. To uncover functional tDRs that are crucial for fibrosis pathways, we utilized an optimized tDR sequencing technique known as ARM-seq to profile the differentially regulated tDRs in cardiac fibroblasts (CFs) during ischemic response. Initial functional screening of the five most significantly regulated tDRs identified a potent anti-fibrotic tDR derived from the 3’-end of tRNA-Asp-GTC (Asp-GTC-3’tDR). Our pilot in vivo studies demonstrate that delivering Asp-GTC-3’tDR mimics to the heart effectively reduces cardiac fibrosis and improves cardiac functions in a mouse myocardial infarction model. Conversely, inhibition of this tDR using our optimal locked-nucleic acid antisense promotes fibrotic responses in the heart. Mechanistically, our preliminary data suggest that autophagy pathway, particularly ribophagy, plays a critical role in mediating the anti-fibrotic effects of Asp-GTC-3’tDR. The primary objective of this project is to investigate the anti-fibrotic roles of Asp-GTC-3’tDR in cardiac fibrosis, with the ultimate goal of developing novel tDR-based interventions for treating cardiac fibrosis. By leveraging a comprehensive toolkit designed to study tDR functions, we aim to elucidate the functional roles and regulatory mechanisms of Asp-GTC-3’tDR in both cell culture and mouse acute and chronic cardiac fibrosis models using the complementary gain-of-function and loss-of-function approaches. This will be followed by the development of innovative strategies for Asp-GTC-3’tDR expression, including the delivery of DNA analogs of Asp-GTC-3’tDR or our engineered CRISPR/Cas13 machinery to the heart, as a means of treating cardiac fibrosis. The successful completion of this study will define a new area of RNA biology within the context of cardiac fibrosis and provide proof-of-concept for targeting Asp-GTC-3’tDR as a novel first-in-class treatment for cardiac fibrosis.