Identification of proteins potentially associated with renal aging in rats.

We established a young (Y)-old (O) rat kidney transplantation model. With this model, we detected no age related differences in renal structure between Y -> Y and Y -> O kidneys or O -> O and O -> Y kidneys. However, we did detect differences in levels of the senescence markers beta-gal and p16 as well as the inflammatory cytokines TNF-alpha and IL-1 beta. Using proteomics analysis we detected 66 proteins associated with suppression of aging and 73 proteins associated with enhancement of aging. After construction of a protein-protein interaction network, a total of 73 nodes and 99 edges were analyzed using MCODE, and three significant modules were selected. GO and KEGG analyses showed that these proteins were mainly located in mitochondria and were largely related to oxidative stress. Among them, SOD1 expression was lower in Y -> O than Y -> Y kidneys and higher in O -> Y than O -> O kidneys. Acetylated (Ac)-NF-kappa B showed the opposite expression profile. In addition, SOD1 expression was higher in primary tubular epithelial cells from young rats than old rats, and SOD1 knockdown led to increased Ac-NF-kappa B expression. These findings suggest the local renal environment, particularly oxidative stress/mitochondrial function, affects renal aging.