Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As a first step in studies on the molecular mechanism(s) underlying gentamicin toxicity, the effect of treating rats with this aminoglycoside antibiotic (100 mg/kg once or twice daily for 3 days) on the analytical subfractionation of the kidney cortex has been examined. DNA was used as a marker for the nuclei, cytochrome oxidase for mitochondria, acid phosphatase for lysosomes, catalase for peroxisomes (with reservations; see the companion paper), NADPH-cytochrome c reductase for the endoplasmic reticulum, p-nitrophenyl-alpha-mannosidase (at pH 5.5) for the Golgi apparatus, AMPase for the plasma membrane in general and alkaline phosphatase for the brush border, and lactate dehydrogenase for the cytosol. In addition, the presumptive lysosomal hydrolases N-acetyl-beta-D-glucosaminidase, p-nitrophenyl-alpha-mannosidase (at pH 4.5), cathepsin D, and DNase II were monitored. Electron microscopy was also performed on the subfractions obtained. The only significant biochemical changes brought about by gentamicin treatment were that N-acetyl-beta-D-glucosaminidase demonstrated both a greater total activity and a larger enrichment in the 104,000gav pellet, while p-nitrophenyl-alpha-mannosidase at pH 4.5 demonstrated the same total activity and a greater enrichment in the 104,000gav pellet. Since myeloid bodies were shown by electron microscopy to sediment primarily with the 500gav and 10,000gav pellets, the biochemical changes seen cannot be associated with these morphological structures. These findings suggest that selective changes in a certain subpopulation(s) of lysosomes or in certain lysosomal enzymes may be involved in the early stages of gentamicin toxicity. On the other hand, no lysosomal membrane damage was observed here, since both the latency of acid phosphatase and the recovery of this activity in the soluble cytosol were unchanged. The present investigation may also have relevance for the dosage and duration of gentamicin treatment chosen in clinical situations.
 ...
PMID:Biochemical effects of gentamicin on rat kidney cortex. II. Analytical subfractionation after short-term, high-dose treatment. 303 Aug

A preliminary study on 9 suckling Wistar rats, which received E. coli stable toxin, and on 12 sham-operated controls showed that acid phosphatase, the marker enzyme for lysosome, was significantly increased in the infected group whereas alkaline phosphatase, glucose 6-phosphatase, succinic dehydrogenase, and proteinase, the marker enzymes for brush border, microsome, mitochondria, and the soluble fraction, respectively, remained unaffected. The results suggest that lysosome, the subcellular organelle responsible for intracellular digestion could be modified by E. coli stable toxin. In another set of experiments, where 7 infected suckling rats and 7 sham-operated controls were used, the maximal activities of lysosomal enzymes (released by Triton X-100) were found to be increased in the infected group confirming the results obtained in the preliminary experiment. The values of the ratio between maximal and basal activity (an expression of the degree of retention of enzymes to lysosome) of acid phosphatase and cathepsin D were also significantly increased, indicating that lysosomal membrane may also be stabilized during the infection. The increased activities of lysosomal enzymes and the increased lysosomal membrane stability suggest that intracellular digestion by lysosome could be increased during E. coli stable toxin infection.
 ...
PMID:Effect of enterotoxigenic Escherichia coli heat stable toxin on intestinal lysosomal enzymes in the suckling rat. 328 51

Subcellular distribution of cathepsin B following subfractionation of the kidney cortex mitochondrial/lysosomal fraction by rate sedimentation indicates that this enzyme is mainly associated with the large, fast sedimenting lysosomes (protein droplets). A small proportion of cathepsin B is also present in the small lysosomes which cosediment with mitochondria, peroxisomes, and brush border and other large membrane vesicles. Amongst this broad spectrum of small lysosomes the distribution of cathepsin B, together with other acid hydrolases is associated with the more rapidly sedimenting lysosomes whilst cathepsin D differs in being associated with the slowest sedimenting lysosomes. Equilibrium banding in sucrose gradients shows the large lysosomes band at a density of 1.235 g/ml and that the small lysosomes have two distinct populations at densities 1.20 and 1.235 g/ml. Cathepsin B (and also cathepsin D and acid ribonuclease) appears to be associated only with lysosomes of high density. The various other acid hydrolases assayed are found in all the lysosomal populations. Small and large lysosomes of high density are very rich in a number of proteinases and therefore most probably represent lysosomal populations involved in the catabolism of proteins taken up from the glomerular filtrate.
 ...
PMID:The lysosomal distribution of cathepsin B in the rat kidney cortex. 360 83

Rat kidney cortex slices were homogenized with a polytron in a isoosmotic medium containing 5 mmol/l EGTA. By two precipitations with MgCl2 (12 mmol/l) and differential centrifugation, brush border membranes were purified. The brush border marker enzymes alkaline phosphatase and aminopeptidase M were found to be enriched 17.0 +/- 5.3-fold and 16.7 +/- 3.7-fold, respectively. By this method, a high yield of brush border membranes was obtained (48.3 +/- 7.9% for alkaline phosphatase; 47.0 +/- 9.5% for aminopeptidase M). The acid phosphatase was enriched 5-fold, whereas other lysosomal enzymes (glucosaminidase, glucuronidase, cathepsin D) were enriched only 0.2-fold. Acid phosphatase activity could not be washed out, but could be separated from alkaline phosphatase and leucine aminopeptidase by means of free flow electrophoresis and sucrose density gradient centrifugation. Vesicles prepared by the presently described Mg/EGTA-method show better transport properties, compared to vesicles prepared by the calcium method of Evers et al. (Evers, C., Haase, W., Murer, H. and Kinne, R. (1978) Membrane Biochem. 1, 203-219), whereas by SDS-polyacrylamide gel electrophoresis, no differences in the protein patterns were observed.
 ...
PMID:A high yield preparation for rat kidney brush border membranes. Different behaviour of lysosomal markers. 611 19

We have studied the cellular content and the extracellular release of cathepsins B and D, and of plasminogen activator, in 2 different tumor cell populations before confluence and after late confluence: the HT-29 colon carcinoma cell line, which contains primarily undifferentiated cells, and a subpopulation derived from this cell line, which contains cells committed to differentiation into mucus-secreting goblet cells after confluence. In both populations, cellular cathepsin-B activity increased after confluence, and latent cathepsin B was found in all culture media. In the parental cell line, cellular cathepsin D activity decreased after confluence; however, cathepsin D was secreted at high levels into the extracellular medium. In contrast, in the subpopulation of cells committed to differentiation, cellular cathepsin D activity increased after confluence, and cathepsin D was not secreted into the extracellular medium, but was immunolocalized in the apical brush border of the differentiated cells. Plasminogen activator of urokinase type was identified by immunocytochemistry. Both subconfluent cell populations, and the post-confluent undifferentiated cell population, produced plasminogen activator activity at similar levels. In contrast, in the differentiated postconfluent cells, the production of plasminogen activator activity was markedly lower. Our data show that the differentiation of HT-29 colon carcinoma cells into mucus-secreting cells impairs the secretion of plasminogen activator and cathepsin D, but does not affect cathepsin B.
 ...
PMID:The state of differentiation of HT-29 colon carcinoma cells alters the secretion of cathepsin D and of plasminogen activator. 791 58

We have studied the intracellular trafficking of cathepsin D in different colon carcinoma cell populations: the HT-29 cell line, composed of >95% undifferentiated cells; 2 subpopulations derived from this cell line, containing cells committed to differentiation into mucin-secreting cells (HT-29 MTX) or enterocyte-like cells (HT-29 G-) after confluence; and the Caco-2 cell line, which spontaneously differentiates into enterocyte-like cells after confluence. Post-confluent undifferentiated HT-29 cells and differentiated enterocyte-like HT-29 G- and Caco-2 cells secrete significant levels of cathepsin D in culture medium, in contrast to post-confluent differentiated mucin-secreting HT-29 MTX cells, which secrete this enzyme at a very low level. The intracellular content and the mRNA level of cathepsin D increase after confluence in the different cell types, particularly in Caco-2 cells, which intensify the secretion of cathepsin D along with the differentiation process post-confluence. Membrane-associated mature cathepsin D was detected in HT-29 cells but not in Caco-2 cells. In the different types of cell, pro-cathepsin D associates with the membrane concomitantly to its binding to an Mr 72,000 protein. Membrane association persists after dissociation of the complex in HT-29 cells but not in Caco-2 cells. In the mucin-secreting HT-29 MTX cells, cathepsin D was immunolocalised to the membrane of mucin vacuoles localised under the brush border. Our results show that cathepsin D can be regulated differently in colon carcinoma cells, and this finding might have specific functional implications for each cell type.
 ...
PMID:Regulation of cathepsin D dependent on the phenotype of colon carcinoma cells. 894 19

Nramp2 (DMT1) is a pH-dependent divalent cation transporter that acts as the transferrin-independent iron uptake system at the intestinal brush border and also transports iron released from transferrin across the membrane of acidified endosomes. In this study, RAW264.7 macrophages and 2 independently derived murine Sertoli cells lines, TM4 and 15P-1, were used to further study the subcellular localization of Nramp2/DMT1 in phagocytic cells, including possible recruitment to the phagosomal membrane. Nramp2/DMT1 was localized primarily to the EEA1-positive recycling endosome compartment, with some overlapping staining with Lamp1-positive late endosomes. After phagocytosis, immunofluorescence analysis and in vitro biochemical studies using purified latex bead-containing phagosomes indicated Nramp2/DMT1 recruitment to the membrane of Lamp1, cathepsin D, and rab7-positive phagosomes. Nramp2/DMT1 was also found associated with erythrocyte-containing phagosomes in RAW macrophages and with the periphery of sperm-containing phagosomes in Sertoli cells. These results suggest that, as for the macrophage-specific Nramp1 protein, Nramp2/DMT1 may transport divalent metals from the phagosomal space.
 ...
PMID:Iron transporter Nramp2/DMT-1 is associated with the membrane of phagosomes in macrophages and Sertoli cells. 1223 76