Interleukin enhancer binding factor 2 (Ilf2) and kidney epithelial stress resilience
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Introduction
In the kidney, epithelial cells of medullary collecting ducts (MCD) are exposed to a harsh microenvironment characterized by hyperosmolality, hypoxia, and oxidative stress. Still, under physiological conditions, they show no apparent signs of cellular injury. We hypothesized that the study of transcription factors (TFs) enriched in MCD cells might identify pathways of stress resilience.
Methods
We generated single-cell expression data from mouse kidneys and predicted in silico candidate TFs with MCD-enriched expression and activity. To investigate the transcriptomic effects of perturbing these candidate TFs, we devised a single-cell CRISPR interference (CRISPRi) screen in mouse inner medullary collecting duct (IMCD3) cells.
Results
We found that perturbation of interleukin enhancer-binding factor 2 (Ilf2), Krueppel-like factor 5 (Klf5), and JunB proto-oncogene (Junb), significantly impacted IMCD3 cells’ gene expression programs, including genes involved in proliferation, apoptosis, and stress-related intracellular signaling, highlighting these TFs as potential regulators of cell-specific resilience. We then focused on Ilf2, validated its impact on gene expression signatures by RNA sequencing, and identified a further role of Ilf2 in the splicing of genes involved in epithelial cellular dynamics and stress responses. Loss of Ilf2 function in IMCD3 cells resulted in nuclear atypia, reduced proliferative capacity, and increased cell death in response to osmotic stress. Ilf2 was upregulated in mouse kidneys during the repair phase following ischemia-reperfusion injury, as were Ilf2-regulated transcripts and splicing events, suggesting that Ilf2 might serve as a post-ischemic signal to facilitate epithelial stress resilience.
Conclusions
Our approach nominates novel pathways of cellular resilience in kidney tubular cells and highlights Ilf2 as a potential target for kidney protection.
Translational Statement
We identify Ilf2 as a transcriptional regulator promoting the stress resilience of renal epithelial cells. Our study provides mechanistic insights into the endogenous mechanisms that protect kidney epithelia from the adverse microenvironment of the renal medulla. Furthermore, Ilf2 activation might constitute a broader mechanism to preserve kidney epithelial integrity under injurious conditions.
