Heat-shock proteins and nucleolar hypertrophy in the liver of rat infused with methionine-free total parenteral nutrition

Infusing a methionine-free solution into rats for 7 days resulted in a marked enlargement of liver nucleoli. By the analysis of two-dimensional gel electrophoresis, a spot 'a' (76 kDa, pI 5.3) stained with Coomassie blue was observed to accumulate highly in liver cytosol from rat infused with methionine-free solution. Metabolically labeling experiments with [35S]methionine showed that 'a' was more heavily labeled in primary hepatocytes of rats infused with methionine-free solution than in those of control rat. To ascertain whether 'a' is one of stress proteins, primary hepatocyte cultures were incubated at 42 degrees C for 2 h. 'a' (76 kDa, pI 5.3) was slightly induced in control hepatocytes but not appreciably in hepatocytes from the treated rat. In contrast, two other spots 'b' (74 kDa, pI 5.6) and 'c' (74 kDa, pI 5.3) were highly induced at 42 degrees C in hepatocytes from control and treated rats. The antibody against the consensus sequence peptide of hsp70 family reacted with 'a' (76 kDa, pI 5.3) as well as 'b' and 'c'. Immunoblot analysis revealed that 'a' accumulates highly in hepatocytes of treated rats. These results indicate that infusion of methionine-free solution into rats induces one member of the hsp70 family in hepatocytes.