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)

The kinin-forming enzyme of rat brain was studied by bioassaying kinin using a rat uterus. The enzyme released a kinin from the partially purified kininogen of rat plasma. The activity is exclusively distributed in the mitochondrial fraction and was detected in the pH range of 2.5-4.0 (optimally at pH 3.0). The enzyme was potently inhibited by pepstatin, but not by aprotinin. Released kinin was extracted by n-butanol and it was purified using Amberlite CG-50 absorption and CM-cellulose column chromatography. The elution profile of kinin from the CM-cellulose column did not coincide with that of bradykinin, Lys-bradykinin or Met-Lys-bradykinin. Isolated kinin was inactivated by treatment with chymotrypsin, but not with trypsin. In addition to the contractile activity on rat uterus, the kinin caused contraction of guinea pig ileum, with the response being potentiated by the presence of bradykinin-potentiator B. It also relaxed a rat duodenum, decreased rat blood pressure, and increased the vascular permeability in guinea pigs. Relative potencies of kinin on these pharmacological activities did not coincide with those of bradykinin. From these results, it is concluded that a kinin-forming enzyme is present in the rat brain. It is a cathepsin D-like enzyme, and furthermore, the enzyme releases a kinin-like peptide from the plasma kininogen fraction.
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PMID:Kinin-forming enzyme in rat brain mitochondria fraction and biological activity of a kinin released from rat plasma kininogen by this enzyme. 674 70

The present study was performed to investigate the enzymatic changes in dystrophic chickens compared to those of dystrophic mice. The activities of 14 kinds of aminopeptidases, 5 kinds of endopeptidase, 4 kinds of glycosidases, phosphatase, esterase, and ribonuclease were measured in muscles of control and dystrophic chickens. When the enzyme activities were expressed as specific activity per unit weight of organs, only some of them were found to be significantly elevated in dystrophic chickens; e.g., alanine aminopeptidase (Ala-AP), Gly-AP and cathepsin D. On the contrary, the activities of alpha-D-glycosidase, alpha-D-galactosidase and alpha-D-mannosidase were significantly decreased. Muscular protein contents of dystrophic chickens also tended to be lower than those of controls. These observations offer a striking contrast with the one obtained in the study on dystrophic mice. However, when expressed as specific activity per mg protein, many enzyme activities were found to be significantly elevated suggesting an extensive abnormality of metabolism in dystrophic chickens. Among 14 kinds of aminopeptidase activities, highly significant elevations were seen especially in AP-A, AP-B, Gly-AP, Ala-AP, Ser-AP, Pro-AP, Leu-AP, Met-AP and Trp-AP. Interestingly enough, a statistical approach suggested a significant correlation between the aminopeptidase changes of dystrophic chickens with those of dystrophic mice. In addition to aminopeptidases, there were highly significant increases in the activities of cathepsin D, alpha-D-glucosidase, beta-D-galactosidase, alpha-D-mannosidase, esterase and RNase. These results indicate that the intramuscular metabolic abnormality of dystrophic chickens are generally different from but partly resembled with those of dystrophic mice.
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PMID:Intramuscular enzyme abnormalities of dystrophic chickens compared to those of dystrophic mice. 701 13

Production of active lysosomal enzymes may involve limited proteolysis of inactive high molecular weight precursors. Precursor processing potentially regulates lysosomal enzyme activity. To test whether rabbit cardiac cathepsin D is first synthesized as a precursor and whether prolonged fasting (a condition affecting both cathepsin D and total cardiac protein turnover) influences precursor processing, rates of cathepsin D synthesis and processing were compared in left ventricular slices of control and 3-d-fasted rabbits incubated in vitro with [(35)S]methionine. (35)S-labeled cathepsin D was isolated by butanol-Triton X-100 extraction, immunoprecipitation, and dodecyl sulfate-polyacrylamide gel electrophoresis. Total cardiac protein synthesis was measured by tracer incorporation and normalized for differences in precursor pool size by direct measurement of [(35)S]aminoacyl-tRNA-specific radioactivity. Relative cathepsin D synthetic rates were obtained by comparing (35)S incorporation into cathepsin D with (35)S incorporation into all cardiac proteins. Enzyme processing was assessed in pulse-chase experiments and assayed by autoradiography. The results indicate that (a) rabbit cardiac cathepsin D is synthesized as a precursor (53,000 mol wt) that is processed to a 48,000-mol wt form, (b) rates of both cathepsin D and total cardiac protein synthesis are similar in control and fasted rabbits, suggesting that decreased enzyme degradation rather than increased synthesis is responsible for the elevated levels of cardiac cathepsin D in starvation, and (c) cathepsin D processing in hearts of fasted animals is incomplete, with accumulation of the precursor during pulse-chase experiments of 6 h duration. Based upon these results, a three-stage model for the regulation of cathepsin D activity in rabbit heart is proposed.
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PMID:Regulation of cathepsin D metabolism in rabbit heart: evidence for a role for precursor processing in the control of enzyme activity. 707 56

A major pre-beta-amyloid protein695 (APP695) processing activity from Alzheimer's disease brain extracts was identified and found to be indistinguishable from the activity of cathepsin D.APP695 processing activity cleaved APP695 into a series of fragments that reacted on immunoblots to a monoclonal antibody (C286.8a) against beta-amyloid-(1-7)-peptide and cleaved N-dansyl-APP-(591-601)-amide at the Glu-Val and Met-Asp bonds. Fragments of 5.5 kDa and 10-12 kDa were formed from the cleavage of APP695 by cathepsin D at the Glu593-Val594 bond, and had the same N-terminus as a minor form of beta-amyloid released by cells. The Lys595-->Asn and Met596-->Leu substitutions found in a pedigree of familial Alzheimer's disease, increased the cathepsin D-catalyzed rate of accumulation of 5.5 kDa and 10-12 kDa C286.8a-reactive fragments 5-10fold. This substitution also increased the rate of N-dansyl-APP-(591-601)-amide cleavage at the Xaa-Asp bond by up to 41-fold. These observations suggest a role of cathepsin D in beta-amyloid formation under certain circumstances.
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PMID:Processing of the pre-beta-amyloid protein by cathepsin D is enhanced by a familial Alzheimer's disease mutation. 752 15

To investigate the intracellular transport and maturation of lysosomal cathepsin D, we carried out an in vivo pulse-chase analysis with [35S]methionine in the primary cultures of rat hepatocytes. Cathepsin D was initially synthesized as a proenzyme of 45 kDa. The proenzyme was subsequently processed, becoming a mature enzyme of 43 kDa. The proenzyme and mature enzyme showed complete susceptibility to endoglycosidase H treatment, suggesting the presence of high-mannose type oligosaccharide chains. The effects of tunicamycin and chloroquine were also investigated. In the presence of tunicamycin, the 42.5-kDa unglycosylated precursor polypeptide appeared in the cell, and this protein was exclusively secreted from the cells without undergoing proteolytic processing. These results support the notion that the oligosaccharide moieties are of importance in addressing the lysosomal hydrolases to the lysosomes. However, in the presence of chloroquine, proteolytic processing of the proenzyme was prevented, and the enhanced release of proenzyme from the cells was observed. These results indicate that the processing of proenzyme to mature enzyme would take place in the lysosomes.
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PMID:Biosynthesis and processing of lysosomal cathepsin D in primary cultures of rat hepatocytes. 755 Jan 14

Proteolytic processing of neuropeptide precursors is required for production of active neurotransmitters and hormones. In this study, a chromaffin granule (CG) aspartic proteinase of 70 kDa was found to contribute to enkephalin precursor cleaving activity, as assayed with recombinant ([35S]Met) preproenkephalin. The 70-kDa CG aspartic proteinase was purified by concanavalin A-Sepharose, Sephacryl S-200, and pepstatin A agarose affinity chromatography. The proteinase showed optimal activity at pH 5.5. It was potently inhibited by pepstatin A, a selective aspartic proteinase inhibitor, but not by inhibitors of serine, cysteine, or metalloproteinases. Lack of inhibition by Val-D-Leu-Pro-Phe-Val-D-Leu--an inhibitor of pepsin, cathepsin D, and cathepsin E--distinguishes the CG aspartic proteinases from classical members of the aspartic proteinase family. The CG aspartic proteinase cleaved recombinant proenkephalin between the Lys172-Arg173 pair located at the COOH-terminus of (Met)enkephalin-Arg6-Gly7-Leu8, as assessed by peptide microsequencing. The importance of full-length prohormone as substrate was demonstrated by the enzyme's ability to hydrolyze 35S-labeled proenkephalin and proopiomelanocortin and its inability to cleave tri- and tetrapeptide substrates containing dibasic or monobasic cleavage sites. In this study, results provide evidence for the role of an aspartic proteinase in proenkephalin and prohormone processing.
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PMID:Characteristics of the chromaffin granule aspartic proteinase involved in proenkephalin processing. 756 75

To investigate the potential contribution of the lysosomal compartment in the processing of amyloid precursor protein (APP) to amyloid beta-peptides (A beta s), we stably overexpressed a series of lysosomal proteases (the cysteine proteases, cathepsins B, L and S, and the aspartic protease, cathepsin D) in a human kidney epithelial cell line (293) transfected to express high levels of beta APP. Preliminary experiments indicated that 293 cells endogenously synthesize cathepsins B, L and D, but not cathepsin S. A beta secretion was assessed by immunoprecipitation and ELISA and found to be increased approximately 2-fold following cathepsin S expression, but to be unchanged (cathepsins B, L) or decreased (cathepsin D) in the other double transfectants. E-64d, an inhibitor of lysosomal cysteine proteases, significantly reduced A beta secretion by the cathepsin S transfectants, but had no effect on cells expressing the other proteases. Radiosequencing of A beta secreted by cathepsin S-expressing cells revealed that a previously unreported variant beginning at Met -1 (relative to the most common A beta N-terminus, Asp -1) accounted for most of the increase in A beta secretion. Immunostaining of human brain sections revealed cathepsin S in cortical neurons and glia in samples of brain from patients with Alzheimer's disease. These results provide evidence in living cells for a pathway in which cathepsin S generates A beta from amyloidogenic fragments of beta APP in the endosomal/lysosomal compartment. This pathway appears to be inducible, distinct from a constitutive pathway used by 293 and other cells to generate A beta, and may be relevant to the pathogenesis of Alzheimer's disease.
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PMID:Lysosomal processing of amyloid precursor protein to A beta peptides: a distinct role for cathepsin S. 757 68

We have reported that mid-region fragments of human parathyroid hormone (hPTH), exemplified by hPTH-(28-48), stimulated [3H]thymidine incorporation into DNA and increased the specific activity of the brain-type isoenzyme of creatine kinase (CK) in both skeletal-derived cell cultures (ROS 17/2.8 cells) and immature rat epiphyseal cartilage and diaphyseal bone, without stimulating cyclic AMP synthesis which is a prerequisite for bone resorption. In the present study, substitution of amino acids in hPTH-(28-48), which resulted in increased resistance to proteolysis, produced variants that stimulated skeletal systems at two orders of magnitude lower concentration than the wild-type fragment. We modified hPTH-(28-48) at Leu-37 by replacement with Met, Thr or Val. Under conditions in which 20% of the native hPTH-(28-48) resisted proteolysis by cathepsin D for 6 h, approx. 40% of the L37V mutant and 70% of the L37T mutant remained intact. Substitution of Met for Phe-34 in addition to Thr for Leu-37, or the substitution of Met for Phe-34 alone, produced 100%-resistant fragments. These variants at residue 34 caused maximal stimulation of CK in ROS 17/2.8 cells at 0.24 nM compared with 24 nM for hPTH-(28-48). The double mutant stimulated CK activity significantly in immature rats, at a minimum dose of 12.5 ng/rat, and caused maximal stimulation at 125 ng/rat, a 10-fold lower dose than for hPTH-(28-48). The effect of the double mutant lasted up to 24 h which differs from the stimulation by hPTH-(28-48) in which CK specific activity returns to the control level at 24 h. This same dose also significantly stimulated CK activity in gonadectomized rats. These results show the advantage of using protease-resistant mid-region variants of hPTH-(28-48) to stimulate bone cells, in terms of lower doses and longer duration of effectiveness, both in vitro and in vivo.
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PMID:Stimulation of creatine kinase activity in rat skeletal tissue in vivo and in vitro by protease-resistant variants of parathyroid hormone fragments. 761 87

An acid protease activity from human brain was found to cleave a fluorogenic peptide substrate encompassing the amino terminus of Alzheimer's amyloid-beta peptide (A beta). The protease was isolated and determined to be cathepsin D based on chromatographic, immunological, and enzymatic data. Analysis of the cleavage sites indicated that cathepsin D hydrolyzed the methionine--aspartate bond generating the in vivo amino terminus of A beta. These data suggested that cathepsin D could be involved in amyloidogenic processing of the amyloid precursor protein. Consequently, cathepsin D from both Alzheimer's-diseased and control brains was compared to determine whether there were any differences which could account for an increase in A beta production in Alzheimer's disease. No differences were detected in isoform composition or tissue content of cathepsin D as measured by 2-D IEF-SDS-PAGE. Enzymological characterization of brain cathepsin D demonstrated that it could undergo a previously undescribed pH-dependent reversible activation. However, that activation appeared identical for both AD and normal brain enzymes. These data demonstrate that concentration, isoform distribution, and several enzymological characteristics of cathepsin D are not distinguishable between AD and normal brain. The pH dependence of cathepsin D activity suggests, however, that its intracellular localization may be important in considering the potential role of cathepsin D in Alzheimer's disease.
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PMID:Cathepsin D from Alzheimer's-diseased and normal brains. 764 17

The way in which the human epididymis modifies spermatozoa during their sojourn in this structure might be clarified by knowledge of the nature of its secretions. We have examined the presence of several lysosomal hydrolases in human epididymal tissue and fluids, and their synthesis and secretion by monolayer cultures. Tissues were obtained from men undergoing orchidectomy for prostatic carcinoma. The enzymes cathepsin D and acid alpha-glucosidase were localised in the lysosomes of epithelial cells from the corpus epididymidis, by an immunocytochemical technique. Cathepsin D was also found in epithelial cells of the efferent ducts within lysosomes, apical vesicles and multivesicular bodies. No immunolocalisation of acid glucosidase in the efferent ducts or on the microvilli of the corpus was demonstrable. Cathepsin D, beta-hexosaminidase (N-acetylglucosaminidase) and alpha-glucosidase were measurable in the luminal fluid from the human corpus epididymidis; beta-hexosaminidase was secreted into the culture medium by confluent monolayers of epididymal and efferent duct cells. Immunoprecipitation of cell extracts and culture medium of these cultures incubated with 35S-methionine revealed that the precursors of cathepsin D and beta-hexosaminidase were synthesized and secreted by such monolayers. Thus, active lytic enzymes are secreted by the human epididymis and could modify sperm membranes.
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PMID:Immunocytochemical localisation of some lysosomal hydrolases, their presence in luminal fluid and their directional secretion by human epididymal cells in culture. 778 Oct 38


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