TY - JOUR
T1 - Depolymerization of hepatocellular microtubules after partial hepatectomy
AU - Bommineni, Vasudeva R.
AU - Chowdhury, Namita Roy
AU - Wu, George Y.
AU - Wu, Catherine H.
AU - Franki, Nicholas
AU - Hays, Richard M.
AU - Chowdhury, Jayanta Roy
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1994/10/7
Y1 - 1994/10/7
N2 - Asialoglycoproteins (ASG) are internalized by hepatocytes by ASG receptor (ASGR)-mediated endocytosis. We have shown previously that when a plasmid DNA, pAlb(9-12)CAT (expressing chloramphenicol acetyltransferase driven by an albumin promoter enhancer), was complexed with an ASG-polylysine conjugate and injected intravenously in rats, 80% of the DNA was internalized by the liver. In normal recipient rats, over 95% of the internalized DNA was degraded in 4 h; the plasmid was undetectable after 48 h. In contrast, when 66% hepatectomy was performed 20 min after DNA administration, the internalized DNA persisted for several weeks in cytoplasmic vesicles (Chowdhury, N. R., Wu, C. H., Wu, B. Y., Yerneni, P. C., Bommineni, V. R., and Chowdhury, J. R. (1993) J. Biol. Chem. 268, 11265-11271). Since microtubules are required for the translocation of ligand-containing endosomes to lysosomes, the site of ligand degradation, we hypothesized that persistence of the endocytosed DNA might be related to changes in microtubular structure and function. To test this hypothesis, we examined hepatocellular microtubules by immunofluorescence confocal microscopy. Liver from untreated rats or sham-operated controls showed a network of fibrillar microtubules throughout the cytoplasm. The extent of the microtubular network was substantially reduced 3-6 h after 66% hepatectomy. By 24 h, microtubules had regenerated. Intraportal infusion of cycloheximide (250 mg/kg body weight) 15 min before 66% hepatectomy, prevented microtubular disruption, indicating that protein synthesis is required for this process. Immunotransblot analysis showed that hepatic α-tubulin concentration remained unchanged through microtubular disassembly and subsequent reassembly, which is consistent with conservation and reutilization of tubulin released by depolymerization of microtubules.
AB - Asialoglycoproteins (ASG) are internalized by hepatocytes by ASG receptor (ASGR)-mediated endocytosis. We have shown previously that when a plasmid DNA, pAlb(9-12)CAT (expressing chloramphenicol acetyltransferase driven by an albumin promoter enhancer), was complexed with an ASG-polylysine conjugate and injected intravenously in rats, 80% of the DNA was internalized by the liver. In normal recipient rats, over 95% of the internalized DNA was degraded in 4 h; the plasmid was undetectable after 48 h. In contrast, when 66% hepatectomy was performed 20 min after DNA administration, the internalized DNA persisted for several weeks in cytoplasmic vesicles (Chowdhury, N. R., Wu, C. H., Wu, B. Y., Yerneni, P. C., Bommineni, V. R., and Chowdhury, J. R. (1993) J. Biol. Chem. 268, 11265-11271). Since microtubules are required for the translocation of ligand-containing endosomes to lysosomes, the site of ligand degradation, we hypothesized that persistence of the endocytosed DNA might be related to changes in microtubular structure and function. To test this hypothesis, we examined hepatocellular microtubules by immunofluorescence confocal microscopy. Liver from untreated rats or sham-operated controls showed a network of fibrillar microtubules throughout the cytoplasm. The extent of the microtubular network was substantially reduced 3-6 h after 66% hepatectomy. By 24 h, microtubules had regenerated. Intraportal infusion of cycloheximide (250 mg/kg body weight) 15 min before 66% hepatectomy, prevented microtubular disruption, indicating that protein synthesis is required for this process. Immunotransblot analysis showed that hepatic α-tubulin concentration remained unchanged through microtubular disassembly and subsequent reassembly, which is consistent with conservation and reutilization of tubulin released by depolymerization of microtubules.
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M3 - Article
C2 - 7929209
AN - SCOPUS:0027997611
SN - 0021-9258
VL - 269
SP - 25200
EP - 25205
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 40
ER -