EPRS1-mediated fibroblast activation and mitochondrial dysfunction promote kidney fibrosis

Kidney fibrosis causes irreversible structural damage in chronic kidney disease and is characterized by aberrant extracellular matrix (ECM) accumulation. Although glutamyl-prolyl-tRNA synthetase 1 (EPRS1) is a crucial enzyme involved in proline-rich protein synthesis, its role in kidney fibrosis remains unclear. The present study revealed that EPRS1 expression levels were increased in the fibrotic kidneys of patients and mice, especially in fibroblasts and proximal tubular epithelial cells, on the basis of single-cell analysis and immunostaining of fibrotic kidneys. Moreover, C57BL/6 EPRS1 tm1b heterozygous knockout ( Eprs1 +/− ) and pharmacological EPRS1 inhibition with the first-in-class EPRS1 inhibitor DWN12088 protected against kidney fibrosis and dysfunction by preventing fibroblast activation and proximal tubular injury. Interestingly, in vitro assays demonstrated that EPRS1-mediated nontranslational pathways in addition to translational pathways under transforming growth factor β-treated conditions by phosphorylating SMAD family member 3 in fibroblasts and signal transducers and activators of transcription 3 in injured proximal tubules. EPRS1 knockdown and catalytic inhibition suppressed these pathways, preventing fibroblast activation, proliferation, and subsequent collagen production. Additionally, we revealed that EPRS1 caused mitochondrial damage in proximal tubules but that this damage was attenuated by EPRS1 inhibition. Our findings suggest that the EPRS1-mediated ECM accumulation induces kidney fibrosis via fibroblast activation and mitochondrial dysfunction. Therefore, targeting EPRS1 could be a potential therapeutic target for alleviating fibrotic injury in chronic kidney disease. EPRS1 inhibition prevents kidney fibrosis and dysfunction Kidney fibrosis, a common result of chronic kidney disease, leads to irreversible kidney dysfunction. Researchers found that the enzyme EPRS1 plays a key role in this process. Researchers discovered elevated EPRS1 levels in fibrotic kidneys of both patients and mice. The study involved patients, mice, and in vitro cells such as NRK-49F, NIH3T3, and HK-2 cells. The researchers used multiple techniques, including immunohistochemistry, western blot, electron microscopy and single-cell RNA sequencing, to identify EPRS1’s role. They found that EPRS1 promotes fibrosis by activating fibroblasts and causing mitochondrial dysfunction. Single-cell RNA sequencing and western blotting identified the pathophysiological