LINEAGE TRACING OF REGENERATING PROXIMAL TUBULE CELLS (STC) BY SINGLE CELL PROFILING IN ACUTE KIDNEY INJURY

Abstract Background and Aims Acute tubular injury accounts for the most common intrinsic cause for acute kidney injury (AKI). The scattered tubular cell (STC) phenotype was discovered as a uniform reaction of tubule cells triggered by injury. Our group was the first to identify an inducible transgenic mouse (PEC-rtTA-mouse) specifically labeling STCs with eGFP. Analysis of the transcriptional factors and associated signaling pathways might reveal the function and role of STCs in AKI. Method Here, we performed single-cell RNA sequencing of unilateral ischemia-reperfusion murine model of AKI 8, 24, 48 hours and 6 and 12 days after AKI induction. Results Genes expressing proximal tubular proteins and transporters were markedly downregulated during transition into the STC phenotype upon injury; but expression recovered over time and upon resolution and tubular cells re-differentiated into proximal tubule cells. This provides evidence for the first time that the STC phenotype is a transient and reversible phenotype triggered by injury. Among cells in the STC phenotype, we could identify 2 sub-clusters; a highly proliferating sub-cluster that in the cell cycle analysis showed the highest proportion of cycling cells. The second eGFP-positive cluster appeared very early after AKI and expressed a distinct set of genes (defined by 7 anchor genes). Some of the highly up-regulated genes are known markers of STCs hence confirming the specificity of our transgenic mouse line. Conclusion Our study provides gene expression patterns specifically in STCs upon injury and repair at multiple time points and suggests that the STC phenotype is a transient and reversible phenotype triggered by injury.