HORMONAL AND DIETARY-REGULATION OF LYSOSOMAL CYSTEINE PROTEINASES IN LIVER UNDER GLUCONEOGENESIS CONDITIONS

The activities of cathepsin B, L, J and Fl in rat liver were significa ntly increased by starvation if compared with normal diet rats, Furthe rmore, the activitiy of cathepsin L increased with glucagon treatment, and the activities of cathepsin L and H decreased significantly with insulin treatment, The changes in cathepsin a and J activities showed the same tendencies as those of cathepsin L and Fl, but the difference s were not statistically significant. The changes in the activities of cathepsin a and L on starvation corresponded with the changes of enzy me protein amounts judged from Western blotting analysis, The levels o f the lysosomal cysteine proteinases and amino acid deaminases in the liver changed in parallel with the hormonal and dietary conditions. Th e increases of alanine amino transferase activity (AAT) started from a much earlier stage than those of cathepsins under the starvation cond ition, Although administration of prednisolone caused marked induction of the deamination enzymes such as AAT, the levels of cathepsins in t he liver were not changed.