Subcellular localisation and induction of NADH-sensitive acetyl-CoA hydrolase and propionyl-CoA hydrolase activities in rat liver under lipogenic conditions after treatment with sulfur-substituted fatty acids.

The effects of sulfur-substituted fatty acid analogues on the subcellular distribution and activities of acetyl-CoA and propionyl-CoA hydrolases in rats fed a high carbohydrate diet were studied. Among subcellular fractions of liver homogenates from rats fed a high carbohydrate diet (20%), the acetyl-CoA and propionyl-CoA hydrolase activities are found in the mitochondrial, peroxisome-enriched and cytosolic fractions. We have shown that the subcellular distribution of acetyl-CoA hydrolase appears to be different from the distribution propionyl-CoA hydrolase activity. Thus, the highest specific activity of acetyl-CoA hydrolase was found in the mitochondrial fraction, whereas the highest specific activity of propionyl-CoA hydrolase was found in the peroxisome-enriched fraction. Rats treated with sulfur-substituted fatty acids, i.e., 3-thiadicarboxylic acid (400 mg/day per kg body weight), showed a significant increase in acetyl-CoA hydrolase activity where the peroxisomal and cytosolic hydrolases were increased 3.9- and 2.7-fold, respectively, compared to palmitic acid treated rats. Similar results were obtained with tetradecylthioacetic acid treated rats. Propionyl-CoA hydrolase activities, in rats treated with these two peroxisome proliferating fatty acid analogues showed increased activity mainly in the mitochondrial and the cytosolic subcellular fractions. Acetyl-CoA hydrolase activity was sensitive to NADH, whereas no stimulation of the propionyl-CoA hydrolase activity was observed in the presence of NADH. The hepatic amounts of acetyl-CoA, propionyl-CoA, and free CoASH were elevated after sulfur-substituted fatty acid treatment. Sulfur-substituted fatty acids also elevated the specific acetyl-CoA hydrolase activity in the mitochondrial fraction and the propionyl-CoA hydrolase activity in the light-mitochondrial fraction. These results, therefore, suggest that acetyl-CoA hydrolase and propionyl-CoA hydrolase are two distinct proteins and that these two enzymes have a multiorganelle localisation.