Multiomics Reveal c-Jun and SLC4A4 as Key Drivers of Kidney Fibrosis in Diabetic Nephropathy

Background: Diabetic nephropathy (DN) is a major cause of chronic kidney disease globally. However, the lack of targeted treatments for renal fibrosis in DN is due to an incomplete understanding of disease progression. We generated a detailed map of human diabetic nephropathy by employing multiplexed single-cell imaging and spatial transcriptomic profiling of DN patients and controls. Methods: We utilized an integrative multi-omic approach, combining single-cell RNA sequencing, chromatin accessibility assays, spatial transcriptomics, and CODEX multiplexed imaging. This comprehensive analysis provided unprecedented spatial and molecular resolution of kidney tissues from DN patients and controls. Results: Our multi-omic analysis revealed novel, cell-type-specific regulatory changes and provided unique mechanistic insights into DN progression. We identified the transcription factor cJun as a novel and pivotal driver of epithelial-to-mesenchymal transition (EMT) in proximal tubule and renal fibrosis. Additionally, we discovered that the sodium bicarbonate cotransporter SLC4A4 is a crucial modulator of proximal tubular injury, causally regulated by cJun. Overexpression of SLC4A4 in human proximal epithelial cells led to reduced expression of epithelial markers (E-cadherin, cingulin), indicative of EMT. Functional assays demonstrated that intracellular pH regulation, highly dependent on SLC4A4, is critical for maintaining epithelial cell function. Disruption of this regulation promoted EMT and exacerbated tubular injury, contributing to DN progression. Using an inducible cJun mouse model, we confirmed that cJun overexpression in tubule drives renal fibrosis in chronic kidney disease. Spatially resolved transcriptomics and CODEX imaging provided detailed insights into the spatial organization of these molecular changes, emphasizing the critical role of multi-omics in uncovering these novel drivers of DN. Conclusion: Our study underscores the power of multi-omics in identifying novel molecular drivers of diabetic nephropathy. The discovery of cJun and SLC4A4 as key regulators highlights their potential as unique therapeutic targets to mitigate renal fibrosis in DN. These findings offer a robust foundation for future research aimed at developing targeted treatments to improve outcomes for patients with DN. Funding: Private Foundation Support