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)

A unique acid proteinase different from cathepsin D was purified from rat spleen by a method involving precipitation at pH 3.5, affinity chromatography on pepstatin-Sepharose 4B and concanavalin A-Sepharose 4B, chromatography on Sephadex G-100 and DEAE-Sephacel, and isoelectric focusing. A purification of 4200-fold over the homogenate was achieved and the yield was 11%. The purified enzyme appeared to be homogeneous on electrophoresis in polyacrylamide gels. The isoelectric point of the enzyme was determined to be 4.1-4.4. The enzyme hydrolyzed hemoglobin with a pH optimum of about 3.1. The molecular weight of the enzyme was estimated to be about 90000 by gel filtration on Sephadex G-100. In sodium dodecylsulfate polyacrylamide gel electrophoresis, the purified enzyme showed a single protein band corresponding to a molecular weight of about 45000. The hydrolysis of bovine hemoglobin by the enzyme was much higher than that of serum albumin. Various synthetic and natural inhibitors of the enzyme were tested. The enzyme was inhbited by Zn2+, Fe3+, Pb2+, cyanide, p-chloromercuribenzoate, iodoacetic acid and pepstatin, whereas 2-mercaptoethanol, phenylmethyl-sulfonyl fluoride and leupeptin showed no effect.
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PMID:Affinity purification and properties of cathepsin-E-like acid proteinase from rat spleen. 3 48

Acid and neutral proteinases were isolated with the purpose of investigating their participation in the breakdown of hypothalamic peptides and proteins. The acid proteinase was purified about 1000-fold from hypothalamus by precipitation with acetone, chromatography on SP-Sephadex G-50, gel filtration through column of G-100 and chromatography on DEAE-Sephadex A-50. The molecular weight of the enzyme was approximately 50.000. Maximal activity against hemoglobin was obtained at pH 3,2--3,5: serum albumin was split much more slowly. Hypothalamus acid proteinase was partially inhibited by beta-phenyl pyruvate, benzothonium cloride, and was completely inhibited by low concentrations of pepstatin. This proteinase splits somatostatin, Substance P and some C-fragments of Substance P. The probable sites of enzyme action on these peptides were determined by the end group dansyl technique. Neutral proteinase was isolated from the supernatant fraction(100.000 g) of a 0,3 M sucrose homogenate of bovine hypothalamus by chromatography on DEAE Sephadex A-50, gel filtration through Sephadex G-100 and rechromatography on DEAE sephadex A-50 using luliberin as substrate. The rates of breakdown of luliberin and denaturated hemoglobin were measured by fluorometric estimation of acid-soluble peptides wieht o-phthaldialdehyde. The purifed enzyme preparations have a pH optimum of activity at 7--7,5. The enzymes molecular weight was approximatelyy 30--40.000. Enzyme activity was inhibited by L-1-tosylamide-2-phenylethylchloromethyl ketone, p-chloromercuribenzoate and divalent ions Co2+, Zn2+ and was significantly enhanced by dithiothreitol. The Km values for the reaction of hydrolysis of luliberin and hemoglobin were 1,33.10(-5) and 5,2.10(-5) M respectively. The neutral proteinase from the hypothalamus cleaves luliberin, somatostatin and Substance P. Sites of action of the enzyme upon those peptides were determined by means of the dansyl technique. The acid proteinase, most likely cathepsin D, and neutral proteinase from hypothalamus, may play an important role in the formation and breakdown of peptide hormones in the hypothalamus.
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PMID:[Breakdown of luliberin, somatostatin and substance P as an effect of hypothalamic endopeptidases]. 4 63

Metallothionein (MT) has been extensively studied over the past several years because of its probable role in endogenous metal homeostasis and cellular protection. A large body of knowledge now exists describing the physicochemical properties of MT as well as the mechanisms involved in MT induction. It has been well established that MT protects tissues from metal toxicity by chelating metals that would otherwise be available to interact with and disrupt vital cell functions. Information on the degradation of metal-saturated MT and the fate of the metals associated with it would be extremely important in predicting metal toxicity. Lysosomes have been targeted as a possible subcellular site for the turnover of MT; however, the susceptibility of MT to degradation by specific acidic proteases (i.e., cathepsins) has not been described. Therefore, the purpose of the present study was to examine the relative abilities of cathepsins B, C, and D to degrade Zn7-MT, Cd7-MT, and apo-MT in vitro. In so doing, the effects of metal species, degree of metal saturation, and pH on the degradation processes were evaluated. Time course experiments revealed that apo-MT was rapidly degraded by all three cathepsins. Cathepsin B degraded apo-MT approximately 36-fold more rapidly than cathepsin C and 45-fold more rapidly than cathepsin D. Therefore, under the in vitro conditions used in this study, the relative potency of the cathepsins tested was cathepsin B much much greater than cathepsin C greater than cathepsin D. In comparison, metal-saturated MT was more than 1000-fold more resistant to degradation by the cathepsins tested. In order to determine how much metal was needed to protect MT against degradation, apo-MT was reconstituted with increasing molar equivalents of Zn2+. The results suggest that as metal to apo-MT ratios increase, less apo-MT substrate is available to the protease and degradation decreases.
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PMID:In vitro degradation of apo-, zinc-, and cadmium-metallothionein by cathepsins B, C, and D. 152 44

The content and distribution of cathepsin D, a lysosomal acidic endopeptidase, were determined by immunochemical methods in rat sciatic nerve near the site of a ligature or after exposure of animals to neurotoxins. In normal sciatic nerve, cathepsin D was localized predominantly in the perinuclear regions of Schwann cells. In ligated nerve, cathepsin D increased equally in both the proximal and distal nerve segments adjacent to the ligature. Although orthograde and retrograde axonal transport of cathepsin D may have contributed to this increase, immunocytochemical methods indicated that Schwann cells or other phagocytic cells accounted for the bulk of the increased cathepsin D content of nerve. Axonal function was nontraumatically altered by the administration of 2,5-hexanedione, acrylamide, B,B'-iminodipropionitrile or zinc pyridinethione. Exposure to any of these neurotoxins raised cathepsin D content throughout the sciatic nerve twofold or more, and greater amounts of immunoreactive cathepsin D in the cytoplasm of Schwann cells could be demonstrated immunocytochemically. These results indicate that changes in cathepsin D content of Schwann cells may be a reflection of their catabolic activity. The increased Schwann cell cathepsin D content in toxic axonopathies is further proof for an enhanced Schwann cell role as a phagocyte resulting from axonal injury.
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PMID:Changes in sciatic nerve cathepsin D after ligation or exposure to neurotoxins. 618 44

Enzymatic activity was investigated in metal-binding proteins from rat epidermal cells. Tris-HCl buffer soluble and KSCN solubilized proteins were extracted stepwise from granular and cornified cells of 2-day old rat epidermis. Each extract was separately applied to a Cu2+ or Zn2+ chelate Sepharose 6B column and the proteins were eluted with buffers of different pHs and finally with EDTA solution. Metal chelate-binding proteins were found in both soluble and solubilized proteins but there was a larger amount in the latter. Affinity of the proteins to bind with Cu2+ chelate was greater than that with Zn2+ chelate. In Tris-HCl buffer extract, histidase activity was detected in Cu2+ chelate-binding proteins, but not in Zn2+ chelate-binding proteins. Acid phosphatase, cysteine proteinase, dipeptidase, cathepsin D, beta-galactosidase, gelatin hydrolase, and superoxide dismutase did not bind to metal chelates although these enzymes, except acid phosphatase, were inhibited by Cu2+, but not by Zn2+. In contrast, KSCN solubilized metal chelate-binding proteins showed plasminogen activator, acid phosphatase, and gelatin and casein hydrolases while histone hydrolase did not bind to either chelate column. Since metal-binding proteins in rat epidermal cells have been shown previously to be histidine- and cysteine-rich proteins concentrated in keratohyalin granules, interaction of metals and the structural proteins with certain enzymes may be involved in the regulation of epidermal cell functions.
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PMID:Enzymatic activity of metal-binding proteins in epidermal cells. 653 44

Cadmium metallothionein (CdMT) nephrotoxicity was studied in rats injected i.p. with a single nonlethal dose of CdMT (0.6 mg of Cd per kg). Within 8 hr of CdMT injection, urine volume and urine sodium excretion were increased and sodium dodecyl sulfate gel electrophoresis of urine proteins showed that elevated levels of low molecular weight proteins were present in the urines of CdMT-treated rats. Urine RNAase activity was also elevated, approximately 7-fold, by CdMT but not by zinc metallothionein (ZnMT) or lysozyme at equivalent protein doses, demonstrating that a proteinuria indicative of proximal tubule cell dysfunction develops as an early response to CdMT exposure. Ultrastructural alterations were also present in animals injected with CdMT but not ZnMT or lysozyme. The earliest alterations occurred in the lysosome compartment of the cell. By 1 hr, the number of small lysosomes in renal proximal convoluted tubule cells increased significantly with no changes in other organelle compartments. By 4 and 8 hr, there was a further increase in lysosome number with a concomitant decrease in size and a marked increase in the number of small clear apical vacuoles. Lysosomal cathepsin D activity was decreased at 4 and 8 hr after CdMT injection, and in vitro studies indicated that this effect was not due to a direct inhibition of the enzyme by Cd++ or CdMT. Thus, both lysosome size and protease activity were rapidly altered by CdMT exposure. Studies of Cd binding in the kidney suggest that non-MT-bound Cd is an important factor in CdMT-associated toxicity. Approximately 97% of the Cd present in the cytoplasm at 1 hr was non-MT-bound. Prior induction of renal MT by treatment with zinc (20 mg of Zn per kg as ZnSO4, i.p. 16 hr before CdMT injection) markedly reduced non-MT binding of Cd++ in kidneys of treated animals and inhibited the alterations in urine volume and low molecular weight protein reabsorption induced by CdMT. These data suggest that acute CdMT exposure provides an excellent system for studying the mechanism of cadmium tubular proteinuria and that the intracellular renal MT pool plays a key role in regulating this process.
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PMID:Cadmium-Metallothionein nephropathy: relationships between ultrastructural/biochemical alterations and intracellular cadmium binding. 670 45

In order to develop a clearer understanding of the role of aberrant protein turnover in the pathogenesis of neurodegenerative disorders, the effect of a series of potentially neurotoxic metal ions on a wide range of proteases (lysosomal and cytoplasmic proteinases and peptidases) from human cerebral cortex was determined in vitro. The response of lysosomal and cytoplasmic proteases to inhibition by metal ion species (0.05-5 mmol/l) was broadly similar; Sr2+, Mg2+, Ba2+ or Ca2+ showed little inhibitory effect at any concentration for most protease types, whilst Cu2+, Cd2+, Pb2+, Mg2+ or Zn2+ showed a substantial degree of inhibition, depending on metal ion concentration and enzyme type. Ca2+ activated neutral proteinases were no more susceptible to general metal ion inhibition than most other protease types. Some proteases showed marked activation of activity in the presence of several metal ion species. Both lysosomal and cytoplasmic proteases were relatively insensitive to inhibition by Al3+, compared with that obtained with other metal ion species. It is of note that cathepsin D was particularly resistant to inhibition by most metal ion species, whilst pyroglutamyl aminopeptidase was particularly susceptible to inhibition by low concentrations of many metal ions. The above data suggest that in considering the potential role of neurotoxic metal ions in the pathogenesis of neurodegenerative disorders of the CNS (via protease inhibition in the intracellular protein degradation pathway), attention should be focused on the interactions between a wide range of metal ion species and protease types, rather than be restricted to the Al3+/calpain system (as is presently the case in Alzheimer's disease research). In particular, the potential role of pyroglutamyl aminopeptidase in intracellular protein degradation (in addition to more specialized functions such as neurotransmitter processing) and the pathological consequences of the susceptibility of this enzyme to inhibition by neurotoxic metal ions requires further investigation.
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PMID:Effect of neurotoxic metal ions in vitro on proteolytic enzyme activities in human cerebral cortex. 758 72

The effects of cadmium on estrogen receptor and other estrogen-regulated genes in the human breast cancer cell line MCF-7 were studied. Treatment of MCF-7 cells with 1 microM cadmium decreased the level of estrogen receptor 58%. Cadmium induced a parallel decrease in estrogen receptor mRNA (62%). Progesterone receptor levels increased 3.2-fold after cadmium treatment. This induction was blocked by the anti-estrogen ICI-164,384. Progesterone receptor mRNA was also increased by cadmium, as well as cathepsin D mRNA. An in vitro nuclear transcription run-on assay showed that cadmium increased the transcription of the progesterone receptor and pS2 genes and decreased transcription of the estrogen receptor gene. These are not general effects of heavy metals, as zinc, 25 and 100 microM, did not affect progesterone receptor protein and mRNA levels. Cadmium stimulated pS2 and progesterone receptor mRNAs in a clone of MDA-MB-231 cells transfected with the human estrogen receptor, but had no effect in MDA-MB-231 cells transfected with antisense estrogen receptor. Cadmium also stimulated an estrogen response element in transient transfection experiments. These data suggest that the effects of cadmium are mediated by the estrogen receptor independent of estradiol. In addition to its effect on gene expression, cadmium induced the growth of MCF-7 cells 5.6-fold.
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PMID:Effect of cadmium on estrogen receptor levels and estrogen-induced responses in human breast cancer cells. 820 12

Tissue remodeling is a key process involved in normal development, wound healing, bone remodeling, and embryonic implantation, as well as pathological conditions such as tumor invasion and metastasis, and angiogenesis. The degradation of the extracellular matrix that is associated with those processes is mediated by a number of families of extracellular proteinases. These families include the serine proteinases, such as the plasminogen-urokinase plasminogen activator system and leukocyte elastases, the cysteine proteinases, like cathepsin D and L, and the zinc-dependent matrix metalloproteinases (MMPs) [1]. Accumulating evidence has highlighted the central role of MMP-driven extracellular matrix remodeling in mammary gland development and breast cancer.
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PMID:Roles of the matrix metalloproteinases in mammary gland development and cancer. 982 15

Psoriasis is a T cell-mediated inflammatory disease characterized by hyperproliferation and by aberrant differentiation. We found cathepsin D and zinc-alpha(2)-glycoprotein, two catalytic enzymes associated with apoptosis and desquamation, to be present in the stratum corneum of the normal epidermis but absent from the psoriatic plaque. Psoriasis is characterized by an altered response to interferon-gamma (IFN-gamma), including the induction of apoptosis in normal but not in psoriatic keratinocytes, often with opposite effects on gene expression of suprabasal proteins. We found that IFN-gamma binding and signaling were attenuated in psoriasis: The IFN-gamma receptor, the signal transducer and activator of transcription STAT-1, and the interferon regulatory factor IRF-1 were strongly up-regulated by IFN-gamma in normal keratinocytes, but not in psoriatic ones. IFN-gamma strongly up-regulated the expression of the catalytic enzymes cathepsin D and zinc-alpha(2)-glycoprotein in normal keratinocytes but down-regulated them in psoriatic ones; the reverse was true of the apoptotic suppressor bcl-2. We believe that the aberrant response to IFN-gamma plays a central role in the pathophysiology of psoriasis, particularly the disruption of apoptosis and desquamation.
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PMID:Response of keratinocytes from normal and psoriatic epidermis to interferon-gamma differs in the expression of zinc-alpha(2)-glycoprotein and cathepsin D. 1069 72


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