Proteolysis in isolated autophagic vacuoles from the rat pancreas. Effects of chloroquine administration.
Administration of the antimalaria drug chloroquine increased the number of autophagic vacuoles (AVs) in the rat pancreas. Ultrastructural analysis showed that AVs contained segregated organelles such as mitochondria, zymogen granules, peroxisomes and small portions of cytoplasm. The maximum number of AVs was observed after 3 h of chloroquine treatment. The effect lasted for 12 h and almost disappeared after 16 h. The increase in AVs caused by chloroquine made it possible to isolate them in a discontinuous Metrizamide gradient with high purity. The proteolytic capacity of the AVs isolated after different chloroquine exposure times was measured after prelabeling pancreatic proteins with an injection of L-(1-14C)leucine 16 h before sacrifice. Protein degradation in isolated AVs increased during the first 6 h of chloroquine exposure and then returned to control values 16 h after the administration. In addition, the activities of two lysosomal enzymes, acid phosphatase and cathepsin B, increased in the AV-fractions following chloroquine treatment. It is concluded that the augmented proteolysis in the isolated AVs is due to a combination of increased substrate content and increased proteolytic lysosomal enzyme activities.
Department of Pathology, Karolinska Institute, Huddinge University Hospital, Sweden.
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Yucel-Lindberg
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Jansson
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Glaumann
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D002401:Cathepsin B / Q000378:metabolism; D002458:Cell Fractionation; D002738:Chloroquine / Q000494:pharmacology*; D008297:Male; D008854:Microscopy, Electron; D010179:Pancreas / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D010447:Peptide Hydrolases; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014617:Vacuoles / Q000187:drug effects / Q000502:physiology*
D011506:Proteins; C018589:lysosomal proteins; D002738:Chloroquine; D000135:Acid Phosphatase; D010447:Peptide Hydrolases; D002401:Cathepsin B