Runt-related transcription factor 1 regulates kidney injury in salt-sensitive hypertension

Hypertension is one of the leading causes of chronic kidney disease (CKD). Among its types, salt-sensitive hypertension (SSH) is strongly linked to CKD. In SSH, hemodynamic stress, inflammation, metabolic dysregulation, and fibrosis drive kidney damage. Despite these known mechanisms, the key regulators coordinating these pathogenic responses are largely unknown. As a result, SSH remains mechanistically complex and lacks effective targeted therapies. Therefore, the main objective of this study was to identify key regulators of SSH-induced kidney damage and their therapeutic potential. Chromatin immunoprecipitation (ChIP)-based upstream regulator analysis was performed on our recently developed multi-organ transcriptomic atlas of SSH to identify key regulators of kidney injury. These analyses revealed runt-related transcription factor 1 (RUNX1) as a major upstream regulator. To test its significance, Dahl SS rats were fed a high-salt (HS) diet (4.0% NaCl; Dyets, Inc., D113756) to induce hypertension and treated with either vehicle or the RUNX1 inhibitor Ro5-3335 (15 mg/kg, intraperitoneally), with normal-salt (NS; 0.4% NaCl, D113755) rats serving as controls. On day 21, kidney injury was evaluated through histopathology, biochemical markers, and expression of inflammatory and fibrotic genes. Mechanistic in vitro studies were performed in human renal proximal tubular epithelial cells (RPTECs) with RUNX1 knockdown under baseline or following stimulation with transforming growth factor beta 1 (TGF-β1; 5 ng/mL) to induce fibrotic signaling observed in kidneys during SSH. We found increased RUNX1 expression in the kidneys of HS diet-fed rats starting from day 7 to 35 and correlated with disease progression. ChIP-based target gene analysis identified over 1,000 RUNX1-regulated genes that were significantly altered in the kidneys of HS diet-fed rats compared with the NS group. Pathway analysis showed that RUNX1-target genes clustered within inflammatory, fibrotic, and metabolic pathways, implicating RUNX1 as a central regulator of SSH pathogenesis. RUNX1 inhibition with Ro5-3335 significantly attenuated renal damage in vivo, assessed on day 21 post-HS diet. RUNX1 inhibition reduced tubular injury, fibrosis, and expression of profibrotic and proinflammatory genes, such as Transforming Growth Factor Beta 1 (Tgfb1), Snail Family Transcriptional Repressor 1 (Snai1), and Lysyl Oxidase Like 2 (Loxl2). Mechanistic studies in RPTECs further supported the in vivo findings. RUNX1 knockdown attenuated TGF-β1–induced epithelial-to-mesenchymal transition (EMT), reflected by preserved epithelial cell morphology and reduced expression of EMT genes such as SNAI2 and Fibronectin 1 (FN1). Moreover, RUNX1 knockdown cells showed significantly protected mitochondrial metabolism under TGF-β1 stimulation, whereas control cells exhibited marked metabolic decline by 72 hours. Specifically, RUNX1 knockdown cells showed sustained levels of ATP Synthase F1 Subunit Beta (ATP5F1B), increased Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-Alpha (PGC-1α; PPARGC1A), and improved glucose utilization as compared to control cells following TGF-β1 treatment. Together, our study identifies RUNX1 as a critical regulator of SSH-induced kidney damage and its inhibition protects the kidney. Therefore, RUNX1 blockade may offer a new targeted strategy to treat SSH-induced kidney damage. Funding: National Institutes of Health Grants R01 DK129227 (to AS and OP), K99 DK143296 (to BX), and T32 HL160529 (to RB), Department of Veteran Affairs grant I01 BX004024 and IK6 RD001204 (to A.S.), and USF Hypertension Kidney Research Center Early Investigator Awards (to RT, LVD, and OK). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.