| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1988: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1987: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1986: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
We investigated the immunocytochemical localization of albumin in the liver of normal rat. Llbumin was detected in the secretory apparatus of all the parenchymal cells and in the phagosomes of the endothelial cells and Kupffer cells (sinus-lining cells, SLC). The results suggest that synthesis and degradation of albumin are carried out in different cell groups.
To confirm this suggestion, we investigated uptake of formaldehyde-denaturated albumin (FDA) labeled with various markers by SLC. The labeled FDA was found only in the endocytic apparatus of the SLC, but never in that of the parenchymal cells. The endocytic apparatus included coated pits (CP), coated vesicles (CV), and tubules (T). the results indicate that FDA is selectively internalized by the SLC through receptor-mediated process.
Next, we studied the time sequence of the endocytosis and degradation of FDA by the SLC. FDA was trapped in the CP and the CV at 10 sec after injection of HRP-FDA conjugate. It appeared in the T after
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30 sec. At 3 - 5 min, many phagloysosomes were formed through fusion of the CV with the T. The CV and T also fused with the phagolysosomes. Later, however, the phagolysosomes rejected the fusion and converted to secondary lysosomes. The degredation of FDA in the phagolysosomes was largely completed at 30 min after the injection.
To identify proteinases concerning with the degradation process in the phagolysosomes, we studied the immunocytochemical localization of cathepsins B, D, and H in the SLC after thfe injection of FDA.Granular staining for cathepsins D and H increased at 20 - 30 min after the injection, but that for cathepsin b did not increased. The results suggest that cathepsin D and H participate in the degradation of FDA.
We studied localization of cathepsins B and H in the intracellular digestive system of the rat kidney proximal tubule cells after injection of HRP. Cathepsins B and H were co-localizes with HRP in the phagloysosomes. The results show that these proteinases are related to the phagolysosomal degradation of HRP in rat kidney. Less
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