المؤلفون: Per E. Stromhaug, Trond Berg, Kristian Berg, Per Ottar Seglen

المصدر: The Biochemical journal. 321

مصطلحات موضوعية: Male, Radiation-Sensitizing Agents, Porphyrins, Endosome, Biochemistry, chemistry.chemical_compound, Cytosol, In vivo, Lactate dehydrogenase, Phagosomes, Animals, Rats, Wistar, Molecular Biology, chemistry.chemical_classification, biology, Leupeptin, Autophagy, Acid phosphatase, Cell Biology, Rats, Enzyme, chemistry, Liver, biology.protein, Lysosomes, Subcellular Fractions, Research Article

الوصف: A photoactivatable porphyrin, tetra(4-sulphonatophenyl)porphine (TPPS4), was shown to accumulate in rat hepatocytes as a linear function of dose after intravenous injection, and to localize predominantly in hepatocytic lysosomes. A major fraction of the lysosomal enzymes acid phosphatase and N-acetyl-β-d-glucosaminidase was inactivated by TPPS4 after 20 h of contact with the drug in vivo in the absence of photoactivation. On exposure of isolated hepatocytes to light, photoactivated TPPS4 caused additional inactivation of the lysosomal enzymes as well as inactivation of intralysosomal lactate dehydrogenase (LDH), a cytosolic enzyme that accumulated in lysosomes as a result of autophagy during a 2 h incubation of hepatocytes at 37 °C in the dark (in the presence of the proteinase inhibitor leupeptin to prevent degradation of intralysosomal LDH). Photoactivation of TPPS4 also induced lysosomal rupture, with a loss of lysosomal enzymes, autophagocytosed LDH, endocytosed 125I-tyramine-cellobiose-asialo-orosomucoid and TPPS4 from the lysosomes. However, LDH-containing autophagosomes, accumulated in the presence of vinblastine (a microtubule inhibitor used to prevent the fusion of lysosomes with autophagosomes or endosomes), were not affected by TPPS4. TPPS4 may thus be useful as a selective lysosomal (or endosomal) perturbant in the study of autophagic–endocytic–lysosomal interactions.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1cdec3921b82f8902d0f2be55b1d2fd7Test
https://pubmed.ncbi.nlm.nih.gov/9003422Test

المؤلفون: Paul B. Gordon, Per Ottar Seglen

المصدر: Biochemical and biophysical research communications. 151(1)

مصطلحات موضوعية: Male, Endocytic cycle, Biophysics, Lactose, Vacuole, Biology, Vinblastine, Biochemistry, chemistry.chemical_compound, Phagocytosis, Autophagy, Animals, Asparagine, Molecular Biology, Cells, Cultured, chemistry.chemical_classification, Rats, Inbred Strains, Cell Biology, Compartment (chemistry), beta-Galactosidase, Endocytosis, Cell biology, Rats, Cytosol, Enzyme, chemistry, Liver, Vacuoles, Lysosomes

الوصف: [14C]Lactose, electroinjected into the cytosol of isolated rat hepatocytes, was sequestered by autophagy, transferred to lysosomes and eventually hydrolysed. Asparagine prevented the fusion between prelysosomal autophagic vacuoles and lysosomes, and caused lactose to accumulate in the former. However, if the hepatocytes were simultaneously allowed to endocytose added β-galactosidase, no lactose accumulation occurred. These results suggest that autophagically sequestered lactose and endocytosed β-galactosidase were delivered to the same prelysosomal vacuole, where the lactose was hydrolysed by the enzyme. The name amphisome is suggested for this new functional compartment, common to the autophagic and endocytic pathways.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a5669d65cf3dfb38c3cff5f8e20b7dedTest
https://pubmed.ncbi.nlm.nih.gov/3126737Test