Renal
fibrosis is the common pathological feature in a variety of
chronic kidney diseases. Aging is highly associated with the progression of renal
fibrosis. Among several determinants,
mitochondrial dysfunction plays an important role in aging. However, the underlying mechanisms of
mitochondrial dysfunction in age-related renal
fibrosis are not elucidated. Herein, we found that Wnt/β-
catenin signaling and renin-angiotensin system (RAS) activity were upregulated in aging kidneys. Concomitantly, mitochondrial mass and functions were impaired with aging. Ectopic expression of Klotho, an antagonist of endogenous Wnt/β-
catenin activity, abolished renal
fibrosis in
d-galactose (d-gal)-induced accelerated aging mouse model and significantly protected renal mitochondrial functions by preserving mass and diminishing the production of
reactive oxygen species. In an established aging mouse model, dickkopf 1, a more specific Wnt inhibitor, and the mitochondria-targeted
antioxidant mitoquinone restored mitochondrial mass and attenuated tubular senescence and renal
fibrosis. In a human proximal tubular cell line (HKC-8), ectopic expression of Wnt1 decreased biogenesis and induced dysfunction of mitochondria, and triggered cellular senescence. Moreover, d-gal triggered the transduction of Wnt/β-
catenin signaling, which further activated
angiotensin type 1 receptor (AT1), and then decreased the mitochondrial mass and increased cellular senescence in HKC-8 cells and primary cultured renal tubular cells. These effects were inhibited by AT1 blocker of
losartan. These results suggest inhibition of Wnt/β-
catenin signaling and the RAS could slow the onset of age-related
mitochondrial dysfunction and renal
fibrosis. Taken together, our results indicate that Wnt/β-
catenin/RAS signaling mediates age-related renal
fibrosis and is associated with
mitochondrial dysfunction.