Relationship between autophagy and the intracellular degradation of asialoglycoproteins in cultured rat hepatocytes
The relationship between autophagy and the intracellular distribution of endocytosed asialoorosomucoid was studied in cultured rat hepatocytes. Overt autophagy was induced by shifting the cells to a minimal salt medium. Incubation in minimal salt medium led to the formation of buoyant lysosomes at the expense of denser lysosomes manifested as a dual distribution of these organelles in Nycodenz gradients. Asialoorosomucoid was labeled with /sup 125/I-tyramine cellobiose. The labeled degradation products formed from this ligand are trapped at the site of degradation and may therefore serve as markers for the subgroup of lysosomes involved in the degradation. In control cells the degradation of the ligand was initiated in a light prelysosomal compartment and continued in denser lysosomes. In cells with high autophagic activity, the degradation of labeled asialoorosomucoid took place exclusively in a buoyant group of lysosomes. These results suggest that degradation of endocytosed ligand takes place in the same secondary lysosomes as substrate sequestered by autophagic mechanisms. These light lysosomes represent a subgroup of active lysosomes which are gradually recruited from dense bodies. Data are also presented that indicate that insulin may prevent the change in buoyant density brought about by incubation in deficient medium.
- Research Organization:
- Univ. of Oslo, Norway
- OSTI ID:
- 6332237
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 15; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
AMINES
ANIMAL CELLS
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MARKERS
CARBOHYDRATES
CELL CONSTITUENTS
CELLOBIOSE
CULTURE MEDIA
DAYS LIVING RADIOISOTOPES
DISACCHARIDES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
GLUCOPROTEINS
HORMONES
HYDROXY COMPOUNDS
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGANDS
LIVER CELLS
LYSOSOMES
MAMMALS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
ORGANOIDS
PEPTIDE HORMONES
PHAGOCYTOSIS
PHENOLS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SACCHARIDES
SOMATIC CELLS
SYMPATHOMIMETICS
TRACER TECHNIQUES
TYRAMINE
VERTEBRATES