WWP2 Regulates Kidney Fibrosis and the Metabolic Reprogramming of Profibrotic Myofibroblasts.

BACKGROUND: Renal fibrosis is a common pathological endpoint in CKD that is challenging to reverse, and myofibroblasts are responsible for the accumulation of a fibrillar collagen-rich extracellular matrix (ECM). Recent studies have unveiled myofibroblasts diversity in terms of proliferative and fibrotic characteristics, which are linked to different metabolic states. We previously demonstrated the regulation of ECM genes and tissue fibrosis by WWP2, a multifunctional E3 ubiquitin-protein ligase. Here, we investigate WWP2 in renal fibrosis and in the metabolic reprograming of myofibroblasts in CKD.

METHODS: We used kidney samples from CKD patients and WWP2 -null kidney disease mice models, and leveraged single cell RNA-seq analysis to detail the cell-specific regulation of WWP2 in fibrotic kidneys. Experiments in primary cultured myofibroblasts by bulk-RNA seq, ChIP-seq, metabolomics and cellular metabolism assays, were used to study the metabolic regulation of WWP2 and its downstream signaling.

RESULTS: The tubulointerstitial expression of WWP2 was associated with fibrotic progression in CKD patients and in murine kidney disease models. WWP2 deficiency promoted myofibroblast proliferation and halts pro-fibrotic activation, reducing the severity of kidney fibrosis in vivo . In renal myofibroblasts, WWP2 deficiency increased fatty acid oxidation and activated the pentose phosphate pathway, boosting mitochondrial respiration at the expense of glycolysis. WWP2 suppressed the transcription of PGC-1α, a metabolic mediator of fibrotic response, and pharmacological inhibition of PGC-1α partially abrogated the protective effects of WWP2 deficiency on myofibroblasts.

CONCLUSIONS: WWP2 regulates the metabolic reprogramming of profibrotic myofibroblasts by a WWP2-PGC-1α axis, and WWP2 deficiency protects against kidney fibrosis in CKD.