DKK1 and age: To further explore the role of Wnt/β‐catenin signaling in mitochondrial dysfunction and the association with age‐related renal fibrosis, we injected mice with the expression plasmid of DKK1, a more specific Wnt inhibitor (He et al., 2010), or the mitochondria‐targeted antioxidant mitoQ (Xiao et al., 2017) after 2 weeks of daily injection of d‐gal in a mouse model of uninephrectomy (Figure 6a), an established age‐associated kidney fibrosis model in which mitochondrial dysfunction and cellular senescence had already occurred (Figure S5).