Cisplatin injury to the kidney is characterized, in part, by inhibition of substrate oxidation,
inflammation, and tubular cell death in the form of apoptosis and
necrosis. Recently, we demonstrated that
cisplatin-induced inhibition of substrate oxidation can be reversed by the administration of
peroxisome proliferator-activated receptor-alpha (
PPAR-alpha)
ligands, resulting in amelioration of renal function. We therefore hypothesize that by improving
fatty acid oxidation in vivo might protect renal function by reducing both apoptosis and
necrosis in
cisplatin-treated mice. Mice subjected to a single
intraperitoneal injection of
cisplatin developed
acute renal failure (ARF) at days 3 and 4. At day 4 after
cisplatin injection
mRNA,
protein levels and
enzyme activity of proapoptotic renal
endonuclease G (Endo G) were increased compared with saline-treated mice. In situ hybridization and immunohistochemical studies localized the increased expression of Endo G
mRNA to the cytosolic compartment and Endo
G protein to the nuclear compartment of proximal tubules in
cisplatin-treated mice. Pretreatment of
PPAR-alpha wild-type mice with
PPAR-alpha ligand WY-14643 reduced significantly
cisplatin-induced increased
protein expression and
enzyme activity of Endo G and prevented the nuclear translocation of mitochondrial Endo G. Morphological examination of tubular injury in the
PPAR-alpha wild-type mice that received
PPAR-alpha ligand and
cisplatin did show significant amelioration of acute tubular
necrosis, as well as a significant reduction in the number of apoptotic cells in the proximal tubule when compared with the
cisplatin-treated group. In contrast, in
PPAR-alpha-null mice treated with the
ligand and
cisplatin, Endo
G protein expression was not reduced and this was accompanied by lack of protection of kidney function. We conclude that
PPAR-alpha ligand protects against
cisplatin-induced renal injury via a
PPAR-alpha-dependent mechanism by reducing the expression and
enzyme activity of proximal tubule Endo G, which results in amelioration of both proximal tubule cell apoptosis and
necrosis.