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At least 19 recordsLinked to original sources
PubMed2000

Cathepsin B, a prognostic indicator in lymph node-negative breast carcinoma patients: comparison with cathepsin D, cathepsin L, and other clinical indicators.

New prognosticators are needed for breast cancer patients after the initial surgical treatment to make therapeutic decisions that ultimately will affect their DFS. These consist of specific proteolytic enzymes including lysosomal endopeptidases. In this study, the activity and protein concentrations of cathepsins (Cats) D, B, and L were measured in 282 invasive breast tumor cytosols. These potential biological prognostic indicators were compared with other histopathological parameters, such as tumor size, lymph node involvement, tumor-node-metastasis stage, histological grade, DNA analysis, and steroid receptors. CatD protein concentration correlated with lymph node involvement. CatB and CatL levels correlated significantly with Scarf-Bloom-Richardson histological grade and were also higher in estrogen-negative tumors, and CatB was higher in larger tumors. As prognostic markers, CatB concentration was significant for increased risk for recurrence in the entire patient population and specifically also in lymph node-negative patients as follows: high CatB concentration (above 371 micrograms/g) in tumor cytosols was significant (P < 0.00) for high risk of recurrence but was of only borderline prognostic significance (P < 0.06) for overall survival of all patients. In lymph node-negative patients, CatB (above 240 micrograms/g, P < 0.003) was highly significant for recurrence-free survival, followed by CatL (above 20 micrograms/g, P < 0.049) and CatD (above 45 nmol/g, P < 0.044) concentrations. For overall survival of node-negative patients, only CatB was a significant (P < 0.014) prognosticator. We conclude that CatB is useful as a prognostic indicator in lymph node-negative patients. This suggests that selective adjuvant therapy should be applied in this lower risk group of patients when high levels of CatB are determined.

Adult↗
PubMed1994

T cell-stimulatory fragments of foot-and-mouth disease virus released by mild treatment with cathepsin D.

Cathepsin D and cathepsin B are endosomal/lysosomal proteases that are thought to play a role during in vivo antigen processing, releasing fragments for binding to major histocompatibility complex class II products and subsequent presentation to T cells. Here we treated purified foot-and-mouth disease virus (FMDV) strain A10Holland with both enzymes. Cathepsin D, but not cathepsin B, was shown to release fragments from reduced or non-reduced FMDV under mild conditions in vitro. Twenty-eight predominant cathepsin D-released fragments were purified by HPLC and identified by amino acid composition analysis and sequencing. The unseparated set of fragments produced (the digest) was able to stimulate T cells from eight vaccinated cattle. With respect to the response to intact virus the extent of the response to the digest differed between animals: four animals could be classified as good responders, three as intermediate responders and one as a low responder. Subsequently, we investigated the proliferative T cell response to a large set of synthetic peptides in detail for two animals, one belonging to the group of good responders, the other being the low responder. The peptides covered all 28 cathepsin D-released fragments analysed and also several sequences not recovered from the digest. In this way seven T cell sites could be identified, five of which coincided with cathepsin D-released fragments. The other two T cell sites were VP2[54-72], being a homologue of a T cell site identified for FMDV strain O1K and the N terminus of VP4. Whether the most dominantly recognized T cell site was recovered from the digest or not was shown to be related to the good or low response to the digest. These findings suggest a role for cathepsin D in the release of some but not all T cell-stimulatory fragments from FMDV.

Amino Acid Sequence↗
PubMed2003

Biochemical and immunohistochemical study on physiological activity and distribution of hepatic cathepsin D.

Cathepsin D (EC 3.4.23.5) is a lysosomal endopeptidase physiologically present at very low concentration in different tissues. The aim of the study was to estimate the physiological activity and distribution of cathepsin D in the liver. Four groups of ten-week-old male Wistar rats were raised without xenobiotics and sacrificed on day 4, 42, 47 and 84 of the experiment, and their livers were taken for immunohistochemical and biochemical investigation. Immunostaining for cathepsin D was evaluated by light microscope. Activity of the free and bound fractions of hepatic cathepsin D was measured spectrophotometrically. Immunohistochemical staining for cathepsin D was positive in Browicz-Kupffer cells in some but not in all rat liver specimens of each experimental group. The staining pattern was cytoplasmic and granular. Occasionally the positive stained endothelial cells were also found. No activity of cathepsin D in hepatocytes was detected. The positive immunostaining was found in livers with high enzyme activity in the biochemical investigation. No significant differences in activity of the free and bound fractions of cathepsin D among the different age groups were noted. However, the higher, age-dependent activity (p>0.05) of the free fraction was observed in the youngest and the two-middle groups of rats that were sacrificed on day 42 and 47 than in the oldest one. The bound fraction did not reveal such changes. It could be concluded that there were no differences in the activity of hepatic free and bound fractions of cathepsin D in male Wistar rats of various reproductive age. The rat Browicz-Kupffer cells revealed the highest activity of cathepsin D.

Animals↗
PubMed1980

Immunochemical difference between cathepsin D and cathepsin E-like enzyme from rat spleen.

The immunological properties of acid proteinases from rat spleen, two types of cathepsin D and a cathepsin E-like enzyme, were examined. The rabbit antiserum was prepared against the major form of cathepsin D (cathepsin D-I) from rat spleen. The antiserum quantitatively precipitated the enzyme activity from the purified cathepsin D-I preparation. On immunodiffusion analysis, the antiserum showed an identical reaction with the minor form of cathepsin D (cathepsin D-II) from rat spleen. Immunoelectrophoresis showed that the precipitin line with cathepsin D-II ran somewhat faster to the anode than that with cathepsin D-I. The cathepsin E-like acid proteinaspe was neither precipitated nor inhibited by the antiserum to cathepsin D-I, indicating that the cathepsin E-like enzyme is different from cathepsin D. Immunological gel diffusion with the antiserum indicated that rat spleen cathepsin D was immunologically identical with cathepsin D obtained from rat brain, thymus, lungs, heart, liver, kidneys, and adrenals.

Animals↗
PubMed2000

Influence of Ukrain and cyclophosphamide administration on HA-1 murine hepatoma and LS lymphoma on aspartic proteinase cathepsin D.

Cathepsin D, the major lysosomal aspartyl proteinase and a mediator of interferon-gamma and tumor necrosis factor-alpha-induced apoptosis, was studied in murine models of LS lymphosarcoma treated by cyclophosphamide (possible apoptosis induction), and HA-1 hepatoma treated by Ukrain (positive antitumor effect). It was found that cyclophosphamide, as well as cyclophosphamide plus Ukrain, increased cathepsin D specific activity in mice with LS lymphosarcoma. Ukrain alone had no effect on cathepsin D activity in LS lymphosarcoma. In HA-1 hepatoma cells cathepsin D activity was not changed compared with intact normal murine liver (day 10) and activity decreased during tumor development (on day 12). Ukrain significantly increased cathepsin D activity in ascitic fluid (day 10) and had a tendency to increase cathepsin D activity in ascitic cells but not to the normal value.

Alkaloids↗
PubMed1982

Thyroglobulin degradation by thyroidal proteases: action of purified cathepsin D.

Cathepsin D has been purified from rabbit thyroids, and its action on thyroglobulin has been examined. The enzyme was obtained in an electrophoretically homogenous form by gel filtration, followed by ion exchange chromatography and affinity chromatography with immobilized pepstatin. In some preparations, the enzyme occurred in a high molecular weight form. The ability of cathepsin D to hydrolyze [125I]thyroglobulin to fragments with a molecular weight of less than 100K was determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This activity showed a pH optimum of 3.5, was greater with reduced thyroglobulin as substrate than with the native protein, and was unaffected by potassium iodide (1-10 mM). Purified cathepsin D rapidly hydrolyzed thyroglobulin to a number of peptide intermediates. Those in the 20-45K molecular weight range had an iodothyronine content equal to or less than that of intact thyroglobulin, but the smallest peptides (apparent molecular weight, less than 2K) were iodothyronine enriched. No evidence was obtained for the release of free hormone by cathepsin D under the experimental conditions used. We conclude that cathepsin D plays a role in the initial breakdown of thyroglobulin in the thyroid and may have some selectivity for the iodothyronine portion of the molecule. The rapid hydrolysis of thyroglobulin that occurs in vivo, however, probably requires the concerted action of cathepsin D with other lysosomal endopeptidases and exopeptidases.

Animals↗
PubMed1977

Human cathepsin D.

Cathepsin D was purified from human liver by a procedure involving autolysis, acetone fractionation, and chromatography on ion-exchange media and organomercurial-sepharose. Multiple forms of the enzyme were then separated by preparative isoelectric focusing. The molecular weight of the protein was found to be 43,000. Its amino acid composition was determined and it was shown to be a glycoprotein. When treated with sodium dodecyl sulphate or chaotropic agents (without reduction) all forms of the enzyme tested gave components of about 28,000 and 14,000 molecular weight. Specific antisera were raised against the enzyme, and the characteristics of immunoinhibition were investigated. Immuno-inhibition of rabbit cathepsin D within living macrophages was shown to interfere with degradation of some proteins endocytosed by the cells. The antisera against human and rabbit cathepsin D were used in immunofluorescent localization of the enzyme in sites of tissue damage in which cathepsin D might be implicated. The characteristics of inhibition of human cathepsin D by pepstatin were established. At pH values below 5, KD values of 5 x 10(-10)M were determined and pepstatin was shown to be an excellent titrant for cathepsin D. In the range pH 5-6.4 DK increased steeply and it was concluded that the binding site for substrate and inhibitor was abolished by a conformational change in the enzyme molecule in which three protons are lost.

Amino Acids↗
PubMed1989

Nonhuman cells correctly sort and process the human lysosomal enzyme cathepsin D.

Cathepsin D, like most lysosomal enzymes, undergoes multiple proteolytic cleavages during its lifetime. Although the significance of the earliest cleavages of cathepsin D is apparent (loss of the NH2-terminal signal peptide and activation peptide), functions of the two later cleavages are not understood and do not occur in all species. To examine these later events, a cDNA coding for human cathepsin D, which is normally processed to a two-chain form, was isolated and then expressed in mammalian cells from species which do not process the enzyme to the two-chain form. Analysis of the expressed human cathepsin D demonstrated proteolytic processing identical with that seen in normal human fibroblasts. Since processing to the two-chain form of the enzyme occurs in the lysosome, these studies revealed that the human cathepsin D was correctly sorted. The data also indicated that the sorting mechanism was conserved between diverse species and that late proteolytic processing in a variety of species was not determined by the presence or absence of the processing enzymes in the cell.

Amino Acid Sequence↗
PubMed1998

Cathepsin D and cathepsin L activities in aortic aneurysm wall and parietal thrombus.

Deterioration of the aortic wall resulting in formation of aneurysms may be caused by increased activity of metalloproteases and lysosomal proteases. The aim of this work was the evaluation of cathepsin D and cathepsin L activities, and activities of inhibitors of cysteine cathepsins in the wall of aortic aneurysms and in parietal thrombus. Aortic aneurysms were obtained during operation. Aortas taken from organ donors and blood clots were used as control material. Activities of cathepsin D and cathepsin L in the aortic aneurysm wall and parietal thrombus were higher than in the control groups. The aneurysm wall showed lower activity of inhibitors of cysteine proteases than the normal aorta. Parietal thrombus had a higher level of cysteine protease inhibitor activity than blood clot. Cathepsin D and cathepsin L present in the aneurysm wall and in the parietal thrombus filling the aneurysm may act on proteins determining elasticity and mechanical resistance of arteries.

Aorta↗
PubMed1988

[Tumor-associated impairment of the processing of hepatoma cathepsin D].

Cathepsin D was purified to apparently homogeneous form from normal human liver and hepatoma. The purified enzyme could not be distinguished between normal liver and hepatoma in terms of specific activity, subunit composition, antigenicity, amino acid composition and tryptic peptides. However, the hepatoma enzyme exhibited more charge heterogeneity to give multiple acidic variant forms which were devoid or much less in the normal liver enzyme. When the hepatoma enzyme was treated with endo-beta-N-acetylglucosaminidase H, the acidic variant forms disappeared and were converted into forms identical to those of normal liver. The content of mannose-6-phosphate in the hepatoma enzyme was twice as much as that in the normal liver enzyme. Thus, charge heterogeneity found in hepatoma cathepsin D is ascribed to increased phosphorylation on oligosaccharides bound to the enzyme, most probably due to cancer-associated, impaired processing in carbohydrate moiety. A significant elevation of cathepsin D activity per tissue proteins was observed in hepatoma as compared to normal liver. In contrast, true specific activity per cathepsin D protein in hepatoma was significantly lowered than that of normal liver. The lower true specific activity in hepatoma tissue may be attributed to an increased content in an inactive, large-molecular precursor form of the enzyme.

Amino Acids↗
PubMed1990

Proteolytic processing of porcine big endothelin-1 catalyzed by cathepsin D.

Cathepsin D, a candidate for endothelin-converting enzyme (ECE), was allowed to act on porcine big endothelin-1 (big ET-1, 1-39). The proteinase primarily cleaved the Asp18-Ile19 and Trp21-Val22 bonds of big ET-1(1-39), with a optimum pH of 3.5. The mature ET-1(1-21), generated by the cleavage between Trp21 and Val22, was subsequently degraded by removal of most of the C-terminal tripeptide (Ile19-Ile20-Trp21). Therefore, cathepsin D is by no means a specific ECE, although the proteinase does cleave the Trp21-Val22 bond of big ET-1(1-39) to produce mature ET-1(1-21). The possibility that cathepsin D can act as an endothelin-degrading enzyme in vivo warrants consideration.

Amino Acid Sequence↗
PubMed1996

Bovine milk procathepsin D and cathepsin D: coagulation and milk protein degradation.

Cathepsin D is an indigenous aspartic proteinase in bovine milk. By competitive enzyme-linked immunosorbent assay the amount of immunoreactive cathepsin D and procathepsin D in bovine skim milk was estimated to be 0.4 microgram/ml. Immunoreactive cathepsin D purified from whey consisted of a small fraction of mature cathepsin D, but the major form was the proenzyme procathepsin D. A preparation of bovine milk procathepsin D was, like mature cathepsin D, able to degrade purified alpha s1-, alpha s2-, beta- and kappa-casein and alpha-lactalbumin, while beta-lactoglobulin was resistant to cleavage. The cleavage sites in these proteins were determined and compared with those of chymosin. Cathepsin D was capable of generating the alpha s1-I, beta-I, beta-II and beta-III fragments originally described from the action of chymosin on the respective caseins, and these fragments were subjected to further proteolysis. Cathepsin D was also able to liberate the caseinomacropeptide from purified kappa-casein, and to coagulate bovine skim milk. This demonstrated that milk contains an indigenous coagulation enzyme present mainly in the whey fraction.

Animals↗
PubMed1999

Characterization of new fluorogenic substrates for the rapid and sensitive assay of cathepsin E and cathepsin D.

Cathepsin E and cathepsin D are two major intracellular aspartic proteinases implicated in the physiological and pathological degradation of intra- and extracellular proteins. In this study, we designed and constructed highly sensitive synthetic decapeptide substrates for assays of cathepsins E and D based on the known sequence specificities of their cleavage sites. These substrates contain a highly fluorescent (7-methoxycoumarin-4-yl)acetyl (MOCAc) moiety and a quenching 2,4-dinitrophenyl (Dnp) group. When the Phe-Phe bond is cleaved, the fluorescence at an excitation wavelength of 328 nm and emission wavelength of 393 increases due to diminished quenching resulting from the separation of the fluorescent and quenching moieties. The first substrate, MOCAc-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the Lys-Pro combination at positions P5 and P4 was designed for specific interaction with cathepsin E, is hydrolyzed equally well by cathepsins E and D (kcat/Km = 10.9 microM(-1) x s(-1) for cathepsin E and 15.6 microM(-1) x s(-1) for cathepsin D). A very acidic pH optimum o was obtained for both enzymes. The second substrate, MOCAc-Gly-Lys-Pro-Ile-Ile-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the isoleucine residue at position P2 was meant to increase the specificity for cathepsin E, is also hydrolyzed equally by both enzymes (kcat/Km = 12.2 microM(-1) x s(-1) for cathepsin E and 16.3 microM(-1) x s(-1) for cathepsin D). The kcat/Km values for both substrates are greater than those for the best substrates for cathepsins E and D described so far. Unfortunately, each substrate shows little discrimination between cathepsin E and cathepsin D, suggesting that amino acids at positions far from the cleavage site are important for discrimination between the two enzymes. However, in combination with aspartic proteinase inhibitors, such as pepstatin A and Ascaris pepsin inhibitor, these substrates enable a rapid and sensitive determination of the precise levels of cathepsins E and D in crude cell extracts of various tissues and cells. Thus these substrates represent a potentially valuable tool for routine assays and for mechanistic studies on cathepsins E and D.

Amino Acid Sequence↗
PubMed2001

Thermal inactivation kinetics of bovine cathepsin D.

Cathepsin D, the principal indigenous acid proteinase in bovine milk, is a lysosomal proteinase, which exists in milk in four forms, including the inactive zymogen procathepsin D. The thermal inactivation kinetics of bovine cathepsin D, isolated from spleen and milk, were studied under isothermal conditions, using a specific HPLC assay to determine residual activity. Inactivation of the blood enzyme preparation followed first order kinetics, with z-values in phosphate buffer (pH 6.7) and skimmed milk of 6.5 and 7.6 degrees C, respectively, the enzyme being far more stable in the latter environment. Inactivation kinetics of the enzyme purified from milk were more complex, and could be best approximated by a double exponential model. Again, stability was higher in milk than in buffer. The double exponential model may indicate differing heat stabilities of isoforms of the enzyme, or stabilization of the enzyme by some milk constituent. It is clear that the enzyme can survive, at least partially, processes such as heating at 55 degrees C for 30 min during manufacture of high-cook cheese varieties (45% survival), and HTST pasteurization (8% survival), and thus may contribute to proteolysis in a range of dairy products.

Animals↗
PubMed1997

Design of sensitive fluorogenic substrates for human cathepsin D.

Cathepsin D is a lysosomal aspartic proteinase that has been implicated in several pathological processes such as breast cancer and Alzheimer's disease. We designed and synthesized a number of quenched fluorogenic substrates with P2 variations in the series AcEE(EDANS)KPIXFFRLGK(DABCYL)E-NH2, where X=cysteine, methylcysteine, ethylcysteine, tert-butylcysteine, carboxymethylcysteine, methionine, valine or isoleucine. Most of the fluorogenic substrates exhibited greater k(cat)/Km ratios than the best cathepsin D substrates described so far. Differences in kinetic constants, which were rationalized using structure-based modeling, might make certain substrates useful for particular applications, such as active site titrations or initial velocity determination using a fluorescent plate reader.

Cathepsin D↗
PubMed2006

A new mechanism for prolactin processing into 16K PRL by secreted cathepsin D.

Cathepsins are lysosomal enzymes that were shown to release the antiangiogenic fragments 16K prolactin (PRL), endostatin, and angiostatin by processing precursors at acidic pH in vitro. However, the physiological relevance of these findings is questionable because the neutral pH of physiological fluids is not compatible with the acidic conditions required for the proteolytic activity of these enzymes. Here we show that cathepsin D secreted from various tissues is able to process PRL into 16K PRL outside the cell. To specifically target extracellular proteolysis, we used tissues from PRL receptor-deficient mice, which are unable to internalize PRL. As assessed by the use of specific inhibitors of proton extruders, we show that the proteolytic activity of cathepsin D requires local acid secretion driven by Na(+)/H(+) exchangers and H(+)/ATPase. Although it is usually assumed that cathepsin-mediated generation of antiangiogenic peptides occurs in the moderately acidic pericellular milieu found in malignant tumors, we propose a new mechanism explaining the extracellular activity of this acidic protease under physiological pH. Our data support the concept that secreted lysosomal enzymes could be involved in the maintenance of angiogenesis dormancy via the generation of active antiangiogenic peptides in nonpathological contexts.

Animals↗
PubMedDate not supplied

Conformation and processing of cathepsin D.

Cathepsin D occurs in two forms, a single polypeptide chain (Mr 44 000) and a non-covalent complex of two peptides of Mr 14 000 and 30 000 that is derived by proteolytic processing of the 44 000 polypeptide. The two forms from bovine spleen are closely similar in secondary structure content, in aromatic amino acid environment and in the two step denaturation behaviour. Enzyme activity is lost irreversibly on denaturation but conformation can be partially regained. The two separated chains will only refold partially and this is related to their positions in the overall structure of cathepsin D. It is suggested that the processing step is related to protein turnover.

Animals↗
PubMed1979

[Isolation and purification of bovine and porcine cerebral cathepsin D].

Cathepsin D was isolated from the grey matter of bovine and porcine large cerebral hemispheres and purified by affinity chromatography on haemoglobin--Sepharose. The isolation and purification of the enzyme also included: acidic extraction, precipitation by ammonium sulfate, dialysis, affinity chromatography, concentration and gel-chromatography on Sephadex G-100. The degree of purification of bovine cerebral enzyme was 3280. The Km value for the enzyme was 2,06 . 10(-5) M. The purified enzyme from bovine brain showed three major and two minor adjacent bands, possessing the cathepsin D activities. The purified enzyme from porcine brain showed only one protein band.

Animals↗