An inducible and podocyte-specific diphtheria toxin receptor knock-in mouse model for studying glomerular injury and chronic kidney disease progression.

Abstract

Podocyte injury and depletion play a central role in chronic kidney disease (CKD) pathogenesis and progression. However, modeling podocyte loss with temporal control and cell-type specificity remains a major challenge. To address this, we developed a previously undescribed knock-in mouse model, podocyte-specific toxin receptor-mediated cell knockout (Pod-TRECK), expressing the human diphtheria toxin receptor under the endogenous Nphs2 (podocin) promoter. This system enables the inducible and podocyte-specific ablation of cells upon diphtheria toxin (DT) administration. We administered graded doses of DT (50-750 ng) and assessed the functional, histological, and molecular consequences of podocyte depletion. We evaluated urinary albumin-to-creatinine ratio, glomerular pathology, and interstitial fibrosis. To characterize transcriptomic changes over time, we performed bulk RNA sequencing on days 5, 14, and 21 post-DT administration. DT treatment induced dose-dependent effects, including albuminuria, nephrin loss, podocyte loss, glomerulosclerosis, and interstitial fibrosis. Transcriptomic profiling revealed a dynamic, time-dependent trajectory. On Day 5, acute inflammatory responses predominated, marked by chemokine and adhesion molecule upregulation. On Day 14, pathways related to cytoskeletal remodeling, extracellular matrix turnover, and mitochondrial dysfunction were enriched. On Day 21, innate immune activity was suppressed, while markers of metabolic exhaustion, oxidative stress, and compensatory antioxidant responses were upregulated. In parallel, we observed a progressive accumulation of oxidative stress-related SNVs (mainly C > T and G > A), indicating genomic instability driven by sustained oxidative stress. Together, the Pod-TRECK model recapitulates key molecular and pathological features of human CKD progression. This platform provides precise temporal control, enabling robust mechanistic studies and preclinical evaluation of podocyte-targeted therapies.