Abstract
Since lysosomes play an important role in maintaining cellular homeostasis by degrading exogenous and endogenous macromolecules with a variety of lysosomal hydrolytic enzymes, wide attention from various aspects has been paid in detail to cellular phenomenon associated with lysosomal activity. Recently, it became evident that lysosomes are mobile, dynamic organelles; they move actively through the cytoplasm to carry out their functions in intracellular digestion, i. e. in heterophagy and autophagy. However, little is known about the regulatory mechanism of intracellular lysosomal movement. In the first part of this paper, we demonstrate that cytoskeletal elements such as actin filaments and microtubules are necessary when lysosomes reveal polymorphic behavior in their shape and size during the heterophagic process by detecting the effects of cytoskeleton-affecting drugs. This is further supported by the morphological evidence that the direct interaction of lysosomes and cytoskeletal elements can be observed in vivo and in vitro. In the second half of this paper, by using cryo-ultrathin section labeling technique, the nature of membranes and matrices of autophagic vacuoles and lysosomes in hepatocytes was examined with respect to the distribution of electric charges and the lectin-binding pattern.
