The Glomerular Kinome in Health and Disease

Background: Pharmacologically targeting the glomerular kinome is an appealing strategy as existing kinase inhibitors could potentially be repurposed for treating kidney diseases. To this end, we investigated alterations in the glomerular kinome signature in rat models of minimal change disease and hypertensive nephropathy in combination with single-nucleus RNA sequencing (snRNA-seq) from biopsies of patients in the Kidney Precision Medicine Project (KPMP). Methods: Sprague-Dawley rats were injected with a single dose of 100mg/kg puromycin aminonucleoside (PAN) and studied for 4 weeks with tissue collected at post-injection days 7, 14, 21, and 28. 13-week-old spontaneously hypertensive rats and age- and sex-matched Wistar-Kyoto rats were studied for 5 weeks before harvesting kidneys. Quantitative isobaric tandem mass tag proteomics was performed on isolated glomeruli, with differentially abundant proteins (DAPs) identified using the LIMMA statistical package and correlated with functional measurements such as urine albumin-creatinine ratio. Publicly available KPMP snRNA-seq data was analyzed using Seurat. Pathway analyses on DAPs and differentially expressed genes (DEGs) were performed using Enrichr and Molecular-Biology-of-the-Cell Ontology. Results: Both rat models showed severe and overlapping perturbations to the glomerular kinome. In PAN rats, alterations in glomerular kinome corresponded to the severity of albuminuria (Figure 1A). Enrichment of the top up- and down-regulated kinases showed cytoskeletal dynamics, adhesion, and the Hippo pathway to be significantly impacted. Patient snRNA-seq data from KPMP similarly showed dysregulation of Hippo-related transcripts which correlated with levels of albuminuria (Figure 1B). Conclusion: In albuminuric kidney diseases, the altered kinome and dysregulation of the Hippo pathway may represent common underlying disease mechanisms. Funding: NIDDK Support - NIDDK Support, NIDDK SupportFigure 1: (A) UMAP of glomerular expression levels of detected kinases during transient glomerular dysfunction in PAN rats (red = injury during days 0-7, blue = recovery during days 8-28). (B) Expression levels of Hippo-related genes in KPMP glomerular cells split by severity of albuminuria.