[Changes in lysosomal enzyme activity in the process of L-cell adipocyte differentiation].

The activity of 4 lysosomal enzymes (acid phosphatase, N-acetyl-beta-D-glucosaminidase, beta-D-galactosidase and acid lipase) was studied at different periods (4, 7 and 14 days) after induction of adipocyte-like differentiation in mouse L-cell culture. The differentiation was induced by adding the 60% bovine serum to the culture medium. On the 5th day after induction, an increase in enzyme activities as compared to uninduced cells, was observed. After 7 days of growth in high serum concentration medium, the increased level of activity was maintained. Cytochemical studies revealed hypertrophy of lysosomal apparatus in perinuclear region in differentiating cells. On the 15th day when the cells were filled with large lipid drops, the activity of the enzymes under study decreased in comparison with the 4 and 7-day periods. The data obtained suggest that increased endocytosis and digestion of serum lipoproteins in lysosomes with subsequent utilization of liberated components is, apparently, the source for lipid accumulation. Induction of lysosomal enzymes in connection with endocytosis and autophagocytosis in the course of adipocyte-like conversion of mouse L-cells, is discussed.