Expression of p53 during apoptosis induced by D-galactosamine and the protective role of PGE1 in cultured rat hepatocytes

The controlled cell death (apoptosis) is involved in the normal regulation of organ size as well as the underlying mechanism of liver disease. Hepatic injury induced by D-galactoseamine (D-GalN) in rats is suitable experimental model to study human liver failure. Many transcription factors are involved in cellular responses, among of them are NF-kβ, TNF-α, AP-1 family; Jun, Fos and p53. Prostaglandin E1 (PGE1) reduces liver injury induced experimentally. P53 is a critical player in the prevention of tumor development. It can contribute directly to DNA repair and inhibition of angiogenesis and to the induction of apoptosis. The regulation of p53 expression is mediated by NF-kβ. This includes regulation of p53 protein stability, control of its subcellular localization and conformational changes that allow activation of the DNA binding activity of p53. Methods: Rat hepatocytes were isolated from male Wistar rats following collagenase perfusion of liver. We examined the change in the expression level of p53 in hepatocytes as a response of treatment with D-GalN (5 and 40 mM) in the presence or absence of PGE1 (1 mM) with or without the proteosome inhibitor (PSI) in protection against apoptosis. The expression of p53 is determined by separating the protein in denatured SDS-PAGE followed by western blotting and detecting the protein using polyclonal antibodies specific for p53. Results: The addition of prostaglandin to control and D-GalN treated hepatocytes increased p53 expression in the cytoplasm during 24 h. While the addition of PSI in the absence of prostaglandin decreased p53 expression at 5 mM D-GalN. This inhibition is reversed in the presence of PGE1 at 5 and 40 mM D-GalN