Rat Liver Ammonia Carbamoyl Phosphate Enzyme ¢ñ, Synthetic Gene Expression In Mammalian Cells

Carbamyl Phosphate Synthetase I (CPSI) is the first key-enzyme, mainly located in the hepatocyle mitochodria. It is charaterized by liver tissue-specific expression and is closely associated with hepatocyte differentiation and changes in expression during the different development periods. It is generally realized that neoplastic transformation is closely related to abnormal cell proliferation. The abnormal cell differentiation may play a more important part in the process of oncogenesis. Our previous work has shown that the activity of CPSI was decreased during hepato-carcinogenesis induced by diethylinitrosamine, and the decrease in enzyme activity was substantiated to be attributed to changes in the amount of enzyme protein and the rate of protein biosynthesis. RNA-DNA hybridization revealed a decrease in CPSI mRNA content during hepato- carcinogenesis. The alteration of CPSI gene expression was closely correlated to that of chromatin structure. These results suggested that changes in CPSI expression would be resulted from an aberration in gene regulation at the transcriptional...