Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.23.5 (cathepsin D)
4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of botulinum toxin (type A) induced muscle paralysis on endocytosis and lysosomal enzyme activities in skeletal muscle were compared with the effects of surgical denervation. Muscle atrophy, measured as decrease in total muscle protein content, was as large or larger after botulinum toxin treatment as after denervation. Endocytic activity, measured as the in vitro uptake of horseradish peroxidase, and the specific activities of the lysosomal enzymes N-acetyl-beta-D-glucosaminidase and cathepsin D were all increased six days after denervation. Only the specific activity of cathepsin D was increased six days after botulinum toxin poisoning. The uptake of horseradish peroxidase and the specific activity of N-acetyl-beta-D-glucosaminidase were also increased eleven days after poisoning. Transverse sections of eleven days botulinum poisoned muscles from animals injected with horseradish peroxidase showed fibres with dense peroxidase staining similar to those seen in denervated muscle although they seemed to occur less frequently. The results show that increases in endocytic activity and lysosomal enzyme activities may occur in skeletal muscle without the presence of degenerating axons. The differences in effects of surgical denervation and botulinum toxin induced paralysis are discussed in terms of what is known about the mechanism of action of botulinum toxin and the possible functional roles of the two lysosomal enzymes studied.
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PMID:Effects of botulinum toxin induced muscle paralysis on endocytosis and lysosomal enzyme activities in mouse skeletal muscle. 376 72

Rabbit alveolar macrophages rapidly internalize and degrade mannosylated bovine serum albumin (125I-mannose-BSA). Trichloroacetic acid-soluble degradation products appear in the cells as early as 6 min after uptake at 37 degrees C, and in the extracellular medium after 10 min. Incubation of endocytic vesicles containing this ligand in isotonic buffers at pH 7.4 + ATP resulted in intravesicular proteolysis, which was inhibited by monensin, nigericin, or ammonium chloride. At pH 5.0, degradation proceeded rapidly and was abolished by lysis of the vesicles with 0.1% Triton X-100. Readdition of lysosomes to the incubation mixture did not increase the rate of prelysosomal degradation. Proteolysis of 125I-mannose-BSA was optimal at pH 4.5, and inhibited by low concentrations of the cathepsin D inhibitor pepstatin A. After subcellular fractionation of the macrophages on Percoll gradients, 125I-mannose-BSA sedimented with prelysosomal vesicles and was not transported to secondary lysosomes. Addition of pepstatin A to extracellular medium during internalization of prebound 125I-mannose-BSA partially inhibited degradation of ligand, and resulted in transfer of undegraded 125I-mannose-BSA to lysosomes after 20 min. Using 125I-bovine serum albumin as a substrate for the protease in the presence of 0.1% Triton X-100, we have shown that as much as 36% of the total pepstatin A-sensitive activity sediments with nonlysosomal membranes. After intraendosomal iodination using lactoperoxidase, a labeled protease was isolated by affinity chromatography on pepstatin-agarose. The labeled protease, which had a subunit size of 46 kDa, was detected in endocytic vesicles after 5 min of internalization. These results suggest that a cathepsin D-like protease is responsible for the degradation of 125I-mannose-BSA in macrophages, and that this ligand is degraded in a prelysosomal vesicle.
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PMID:Macrophage endosomes contain proteases which degrade endocytosed protein ligands. 390 94

Cathepsin D was visualized in free pulmonary alveolar macrophages (AM), in oil-induced peritoneal macrophages (MN) and in rabbit pulmonary and dermal BCG lesions with unlabeled antibodies and the peroxidase-antiperoxidase (PAP) complex. Large amounts of cathepsin D were present in AM and lower amounts in MN. In the lung this enzyme was richest in the alveolar macrophages that accumulated around the BCG lesions. In the dermal lesions, cathepsin D was in highest concentration in macrophages at the border of the necrotic (liquefying) centers. It was also found in high concentration in keratinizing cells of the dermal epithelium and hair follicles. It did not, however, increase appreciably in many of the activated macrophages that stained intensely for the lysosomal enzyme beta-galactosidase. In fact, many epithelioid cells with high beta-galactosidase activity contained no visible cathepsin D. This proteinase does not, therefore, seem to be primarily involved in the lymphocyte-mediated macrophage activation associated with acquired cellular resistance to tubercle bacilli. It is probably more involved with cell autolysis, with the digestion of ingested necrotic debris and, in all likelihood, with the process of liquefaction, the most adverse event in the pathogenesis of tuberculosis in man.
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PMID:The role of cathepsin D in the pathogenesis of tuberculosis. A histochemical study employing unlabeled antibodies and the peroxidase-antiperoxidase complex. 480 13

BCG lesions were produced in the skin of rabbits, and biopsies were performed at 7, 21, and 42 days, when they were developing, maximal in size, and almost healed, respectively. Tissue sections were prepared and stained histochemically for several enzymes. The percentage of cells stained for a given enzyme and the distribution of such cells within lesions of various ages were determined. Seven-day BCG lesions contained few esterase- and beta-galactosidase-positive macrophages, but 21-day lesions contained many, especially in the viable and nonviable tuberculous granulation tissue at the edge of the now prominent caseous necrotic center. Both 7-day and 21-day lesions contained many acid phosphatase- and cathepsin-D-positive macrophages, which were numerous in the more peripheral parts of the lesion, where little or no necrosis was present. Enzyme patterns in 42-day lesions resembled those in 21-day lesions. The role of each of these enzymes in the development and regression of the BCG lesion is unknown. Nonetheless, these studies clearly demonstrate that this macrophage population is heterogeneous and that macrophages carry out different functions in different parts of the lesion at different times. Histochemical techniques were developed to stain two enzymes in the same tissue section. The first stain usually contained a naphthol substrate and produced a red color; the second stain contained an indoxyl substrate and produced a blue color. A cell staining with both was colored purple. The peroxidase-antiperoxidase immunocytochemical technique for cathepsin D (producing a red color) was also employed. 1) Red esterase (hydrolyzing naphthol AS-D acetate) and beta-galactosidase, and 2) red esterase and blue esterase (hydrolyzing 5-bromo-4-chloro-indoxyl acetate), probably the same enzyme, were usually present in the same macrophage. In contrast, each of the following enzyme pairs was usually present in a different macrophage: 3) cathepsin D and beta-galactosidase, 4) cathepsin D and blue esterase, 5) acid phosphatase and beta-galactosidase, and 6) acid phosphatase and blue esterase. Roughly 10% of the macrophages stained for one enzyme existed side by side with macrophages stained for a different enzyme. These results suggest that local macrophage activation is under two levels of control. The first, macrolocal control, would determine the overall enzyme distribution in the lesion; whereas the second, microlocal control, would determine enzyme distribution on a cell-by-cell basis, ie, how two neighboring macrophages can each be rich in a different enzyme.
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PMID:Macrophage functional heterogeneity in vivo. Macrolocal and microlocal macrophage activation, identified by double-staining tissue sections of BCG granulomas for pairs of enzymes. 615 72

We have demonstrated that incubation of rat liver microsomes with N-hydroxy-2-acetylaminofluorene (N-OH-AAF) leads to formation of a 2-nitrosofluorene-membrane lipid adduct. This adduct exists as a nitroxyl free radical, termed N-O-LAF, in its oxidized state. When microsomes were incubated with the sulfhydryl binding agent, rho-hydroxymercuribenzoate, a larger amount of N-OL-LAF formed. We interpret this as a slowdown in the rate of endogenous chemical reduction of carcinogen-membrane lipid adduct. In this paper we present evidence that N-OH-AAF is deacetylated by a microsomal enzyme to form N-hydroxy-2-aminofluorene and this is then oxidized to 2-nitrosofluorene which adds covalently to membrane lipid double bonds to form N-O-LAF. Various antioxidants, peroxidase inhibitors, and P450 substrates and inhibitors were ineffective in altering the amount of N-O-LAF formed from N-OH-AAF; but two esterase inhibitors, dietyl-rho-nitrophenylphosphate and alpha-toluene-sulfonyl fluoride, prevented N-O-LAF formation. Of the following purified enzymes tested: porcine liver carboxyl esterase, pepsin, chymotrypsin, cathepsin D, ficin, papain, leucine aminopeptidase, Naja naja phospholipase, acetylcholinesterase (type I), trypsin (type I and V) and epoxide hydrase; only carboxyl esterase was effective in deacetylating N-OH-AAF.
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PMID:The deacetylation of N-hydroxy-2-acetylaminofluorene by rat liver microsomes and carboxyl esterase. 626 Mar 32

The spatial distribution of horseradish peroxidase (HRP) uptake has been studied by light- and electron microscopy in the denervated hemidiaphragm of the mouse. Segments with high HRP uptake were observed in a band centrally located in the denervated muscle. This distribution is similar to the well-known innervation pattern of the diaphragm. Ultrastructural studies demonstrated a high incidence of postsynaptic folds in close proximity of fibre areas with high intracellular content of HRP. 8-12 days after denervation a large number of fibres showed segments of high HRP uptake. 2-4 days after denervation very few such segments were observed. Biochemical studies also demonstrated an increase in HRP uptake after denervation occurring primarily in the endplate region. The activities of the lysosomal enzymes N-acetyl-beta-D-glucosaminidase, acid phosphatase and cathepsin D all increased after denervation, most prominently in the endplate region. It is suggested that the observed segmental uptake of HRP and lysosomal activation reflects a process for rapid membrane turnover in denervated muscle.
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PMID:Uptake of horseradish peroxidase in denervated skeletal muscle occurs primarily at the endplate region. 653 Jun 15

The in-vivo uptake of exogenously applied horseradish peroxidase and the activities of the lysosomal enzymes acid phosphatase and cathepsin D were studied histochemically and/or biochemically in innervated and 2-14 day-denervated tibialis anterior muscles of the mouse. The biochemically determined uptake of horseradish peroxidase showed a large increase already 4 days after denervation. The activities of the lysosomal enzymes increased in a more gradual fashion, and only cathepsin D showed an increase in activity when expressed as total activity per muscle. Histochemically horseradish peroxidase was found to be localized in muscle fibres in characteristic spindle-shaped segments after denervation. The main increase in the number of such segments per transverse section of the muscle occurred between 3 and 6 days after denervation. In serial sections these segments frequently showed positive staining also for acid phosphatase. It is concluded that exogenously applied horseradish peroxidase is taken up into the lysosomal system, which after denervation becomes organized into characteristic spindle-shaped segments in the muscle fibres. The endocytic activity of muscle fibres increases early after denervation. This is followed by a more gradual increase in activity of lysosomal enzymes and finally by an organization of the lysosomal system into characteristic spindle-shaped segments. The results are compatible with the working hypothesis that increased endocytosis may initiate lysosomal activation in denervated skeletal muscle.
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PMID:Lysosomes in skeletal muscle following denervation. Time course of horseradish peroxidase uptake and increase of lysosomal enzymes. 671 13

Lysosomal cathepsin D has been localized with the electron microscope employing an indirect immunohistochemical method using peroxidase labeled, monospecific antibody Fab' subunits. The acid proteinase has been demonstrated within secondary lysosomes of cardiac myocytes and interstitial cells, but not in components of the Golgi apparatus or endoplasmic reticulum. Incubations with a variety of peroxidatic inhibitors suggests that the staining that is observed in secondary lysosomes is attributable to the peroxidase-labeled antibody and not to endogenous oxidation of DAB. The protocol outlined here provides a reproducible method to localize the major lysosomal acid proteinase of the heart at the subcellular level.
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PMID:The distribution of lysosomal cathepsin D in cardiac myocytes. 698 33

The localization of cathepsin D (CD) in normal adult rat neural tissue was determined with an indirect immunoperoxidase technique utilizing rabbit anti rat brain CD followed by a horseradish peroxidase conjugate of the Fab portion of goat antirabbit IgG. The immunoreactive enzyme protein was distributed predominantly in a granular pattern, presumably lysosomal, in neurons and choroid plexus epithelium. Smaller amounts were detected in oligodendrocytes and ependymal cells. The neuronal localization included the perikaryon and its processes, was widely distributed, and displayed a range of staining intensities in different anatomical areas. Immunoreactive CD was heavily concentrated in brain stem and spinal cord motoneurons, large neurons of the caudate nucleus, neurons of several nuclear groups, especially the paraventricular and supraoptic, in the hypothalamus, and neurons of superior cervical and dorsal root ganglia. CD was also readily detected in brain stem sensory neurons, pyramidal cells of the hippocampus, inferior olive and Purkinje cells, but was absent or present in very small quantities in the granule cells of the cerebellar cortex, the more superficial layers of the neocortex, and smaller neurons of the caudate nucleus. This distribution suggests that CD may have a major role in specific chemical events in neural functions and peptidergic pathways and could be involved in the alterations of certain neural structures in disease states.
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PMID:Immunocytochemical localization of cathepsin D in rat neural tissue. 702 Aug 77

The molecular charge of the macromolecule, horseradish peroxidase (HRPase, 40 000 mol. wt), was modified to yield highly anionic (PI less than 3.68) and cationic (PI = 9.5-10.5) derivatives. The effects upon the interactions between HRPase and arterial endothelium were then studied in vitro. The net rate of uptake of HRPase into endocytic vesicles and vacuoles of confluent endothelium was influenced by its molecular charge, there being less internalization of the anionic HRPase than of the native (pI = 7.9-8.2) and cationic derivatives. The molecular diameter was not significantly different between the cationic (Ae = 28.8 A), anionic (Ae = 31.2 A) and native (Ae = 29.6 A) HRPase. The rate of uptake of [U-14C]sucrose, a tracer of bulk fluid endocytosis, was unaffected by the presence of the differently charged HRPase, indicating that the volume of vesicles formed per cell per hour remained constant. The intracellular fate of HRPase of different charge was investigated biochemically and morphologically. The rate of loss of internalized HRPase activity in the endothelial cells approximated first-order kinetics. The rate of disappearance of intracellular HRPase activity was much greater for cationic (t1/2 = 8 h) and native (t1/2 = I 8 h) than for anionic HRPase (t1/2 = 80-100 h). By electron microscopy, all 3 forms of HRPase were restricted to intracellular membrane-bounded vesicles and vacuoles consistent with a vesicle-lysosomal pathway. Studies with purified lysosomal cathepsin D indicated that the differences in the intracellular half-lives of HRPase may be attributable in small part to decreased and increased rates of lysosomal proteolysis of anionic and cationic HRPase, respectively, in comparison with native HRPase. Pre-labelling of endothelial secondary lysosomes by inhibitors of phagosome-lysosome fusion (dextran sulphate, polyglutamate) lengthened the intracellular half-life of native HRPase, while introduction of cationic ferritin to cells pulsed with anionic HRPase greatly decreased its half-life. Thus an influence of molecular charge upon endosome-lysosome fusion cannot be excluded. The studies indicate that the net charge carried by exogenous HRPase influences both its internalization in endocytic vesicles and its subsequent intracellular fate, which in turn may be modified by the introduction of other differently charged macromolecules. These results are discussed in relation to macromolecular transport by vascular endothelium in vivo.
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PMID:Influence of molecular charge upon the endocytosis and intracellular fate of peroxidase activity in cultured arterial endothelium. 730 13


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