Immunocytochemical localization of liver-specific proteins in pancreatic hepatocytes of rat.

Hepatocytes are induced in the pancreas of rats maintained first on a copper-deficient diet for 8 weeks and then on normal rat chow. These cells are morphologically identical to parenchymal cells of the liver. These hepatocytes contain two liver-specific proteins: carbamyl phosphate synthetase I, a mitochondrial matrix protein that participates in the conversion of ammonia to carbamyl phosphate; and urate oxidase, an enzyme that catalyzes the oxidation of uric acid to allantoin. In addition, we also present evidence indicating that dietary administration of ciprofibrate induces peroxisomal beta-oxidation pathway enzymes, while the levels of catalase are unaltered in pancreatic hepatocytes. These observations along with the previously published results further establish the identity of pancreatic hepatocytes to parenchymal cells of liver and clearly indicate that transdifferentiation of pancreatic cells to hepatocytes is associated with activation of several liver-specific genes.