BALB/c Fech(m1Pas) mice have a mutated
ferrochelatase gene resulting in protoporphyria that models the hepatic injury occurring sporadically in human
erythropoietic protoporphyria. We used this mouse model to study the development of the injury and to compare the dysfunction of
heme synthesis with hepatic gene expression of liver metabolism, oxidative stress, and cellular injury/
inflammation. From an early age expression of total
cytochrome P450 and many of its
isoforms was significantly lower than in wild-type mice. However, despite massive accumulation of
protoporphyrin in the liver, expression of the main genes controlling
heme synthesis and catabolism (Alas1 and Hmox1, respectively) were only modestly affected even in the presence of the
cytochrome P450-inducing CAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]
benzene. In contrast, in BALB/c mice exhibiting
griseofulvin-induced hepatic protoporphyria with induction and destruction of
cytochrome P450, both Alas1 and Hmox1 genes were markedly up-regulated. Other expression profiles in BALB/c Fech(m1Pas) mice identified roles for oxidative mechanisms in liver injury while modulated gene expression of hepatocyte
transport proteins and
cholesterol and
bile acid synthesis illustrated the development of
cholestasis. Subsequent
inflammation and
cirrhosis were also shown by the up-regulation of
cytokine, cell cycling, and
procollagen genes. Thus, gene expression profiles studied in Fech(m1Pas) mice may provide candidates for human polymorphisms that explain the sporadic hepatic consequences of
erythropoietic protoporphyria.