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)

Morphological and biochemical evidence indicates that in several cell types, lysozyme is found in both lysosomes and the medium. Here we report that in calcitriol-treated human promonocytes U937, in which approx. two-thirds of the synthesized lysozyme is secreted, most of the intracellular lysozyme co-localizes with cathepsin D in lysosomal organelles. In the presence of NH4Cl the lysosomal targeting of procathepsin D, but not that of lysozyme, is inhibited. In the presence of 4 beta-phorbol 12-myristate 13-acetate (4 beta-PMA; 'TPA'), the lysosomal packaging of lysozyme is almost completely inhibited, while that of procathepsin D is only partially so. However, the inhibition of the lysosomal targeting of procathepsin D by NH4Cl and 4 beta-PMA is additive. The targeting of lysozyme is partially inhibited in the presence of R-59022, an inhibitor of diacylglycerol kinase, whereas it is not affected by 4 alpha-phorbol 12-myristate 13-acetate, an isomer of 4 beta-PMA that does not activate protein kinase C. It is concluded that in U937 cells both carbohydrate-dependent and -independent recognition contributes to the lysosomal targeting of soluble proteins. We suggest that the carbohydrate-independent traffic of proteins to lysosomal compartments is controlled by a signalling pathway involving protein kinase C.
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PMID:Distinctive inhibition of the lysosomal targeting of lysozyme and cathepsin D by drugs affecting pH gradients and protein kinase C. 809 11

Complementary DNAs (cDNAs), corresponding to the human proteinases cathepsins D and O and proteinase inhibitors alpha2-macroglobulin and PP5/TFPI-2, have recently been isolated and identified from a subtractive human ciliary body library. In the present study we determined: (i) their pattern of expression in the human eye; (ii) the ability of the ciliary body and/or ciliary epithelial cells to synthesize and secrete cathepsin D and alpha1-antitrypsin in vitro; and (iii) whether alpha1-antitrypsin expression in cultured ciliary epithelial cells is modulated by protein kinase C activation. Northern analysis demonstrated that the ciliary body expresses high levels of cathepsins D and O, alpha2-macroglobulin, alpha1-antitrypsin and PP5/TFPI-2 transcripts. Western blot analysis and immunoprecipitation experiments with cathepsin D and alpha1-antitrypsin antibodies indicated that metabolically labeled ciliary body explants and/or ciliary epithelial cells in vitro with 35S-methionine, synthesize and secrete these proteins. Cultured nonpigmented ciliary epithelial ODM-2 cells, in response to phorbol-12-myristate 13-acetate (PMA), but not to the non-protein kinase C binding phorbol ester 4 alpha-phorbol didecanoate (PDBu), elicited up-regulation (up to 5-fold) of transcription, synthesis and secretion of alpha1-antitrypsin. These results provide in vitro evidence that the ciliary epithelium synthesizes and secretes a selective group of proteinases and proteinase inhibitors detected also in aqueous humor. The expression of at least of one of the proteinase inhibitors, alpha1-antitrypsin, can be modulated in response to phorbol ester.
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PMID:Gene expression of proteases and protease inhibitors in the human ciliary epithelium and ODM-2 cells. 926 97

A major aldehydic end product of the peroxidation of arachidonic acid, 4-hydroxy-2,3-nonenal (HNE), has recently been considered for its potential involvement in a variety of cell functions. Here we report on the differential regulation of rat hepatocyte protein kinase C (PKC) isoforms by concentrations of HNE actually detectable in specific biological fluids or tissues. PKC betaI and, to a much greater extent, PKC betaII activities were markedly increased by 0.1 micromol/L HNE (final concentration in cell medium) whereas they were unaffected or even inhibited by 1 to 10 micromol/L HNE. On the contrary, the calcium independent PKC delta activity was inhibited by 0.1 micromol/L and increased by 1 and 10 micromol/L. Further, we show here that HNE-induced stimulation of PKC betaI and betaII activities, both in cytosolic and in membrane fractions, is paralleled by a marked stimulation of the anterograde transport of a lysosomal enzyme within the central vacuolar system. In fact, the treatment with 0.1 micromol/L HNE accelerated the PKC-dependent transport of lysosomal procathepsin D from the trans-Golgi network to the endosomal-lysosomal compartment and, in addition, increased the exocytosis of mature cathepsin D (CD) from these compartments. On the other hand, hepatocyte cotreatment with a selective inhibitor of classic PKCs prevented the aldehyde-induced activation of CD transport. These results support the possible involvement of HNE in the PKC-dependent regulation of the traffic of secretory glycoproteins, and point to remarkable implications of this aldehyde in the pathophysiology of various exocytic processes including hepatocyte lipoprotein secretion.
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PMID:Regulation of rat hepatocyte protein kinase C beta isoenzymes by the lipid peroxidation product 4-hydroxy-2,3-nonenal: A signaling pathway to modulate vesicular transport of glycoproteins. 1021 44

We show that in the rat basophilic leukemia cell line RBL, the physiological stimulation of the IgE receptor or direct activation of PKC leads to the missorting of proteins to the plasma membrane, diverting them from their normal intracellular destination. This is demonstrated for two classes of proteins that are normally targeted to the secretory lysosomes via completely different mechanisms, i.e. proteoglycans and the aspartic protease cathepsin D. In the latter case, normal processing of the enzyme is also affected, leading to secretion of the immature form of cathepsin. The present study shows how completely different sorting mechanisms, such as those for delivering proteoglycans and cathepsin D to secretory lysosomes, might share common regulatory signals and are similarly affected when the levels of these signals are perturbed. Finally, protein kinase C appears to be a major player in the signal transduction pathways, leading to proteoglycan and cathepsin D missorting.
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PMID:Regulation of protein sorting at the TGN by plasma membrane receptor activation. 1065 66

The macrolide antibiotics are bacteriostatic agents interfering with protein synthesis but they are taken up by phagocytic cells, e.g. macrophages, neutrophils and fibroblasts which take up infectious organisms into phagosome-lysosomal vaculoes. Recent studies have suggested that these macrolide antibiotics block the spread of infections by mechanisms associated with the inflammation process. Herein is a study with clarithromycin using human THP-1 monocytes, a phagocytic cell which has not been studied to date. Clarithromycin was rapidly taken up by the monocytes (approximately 1%) utilizing both saturable carrier and passive processes at pH 7.4 but was exclusively passive at pH 6.8 and 5.0. The carrier process was energy and temperature dependent and appeared to be linked to certain ion channels. Efflux of the drug was rapid and complete in 1 hr. Intracellular disposition showed 74% in the cell sap and 11% in the nucleus. Upon stimulation with zymogen A or bacteria significant increases of uptake occurred in the isolated lysosome-phagosomes. Examination showed that initially clarithromycin treatment triggered the release of NO, H2O2, IL-1 and TNFalpha from the monocytes, known mediators of inflammation, but also mediators which cause bacterial cell death or apoptosis. The activity of the monocyte marker hydrolytic enzyme NAG was elevated at this time as well as protein kinase C activity. Treatment from 2-4 hr with clarithromycin appeared to reverse this process in that the chemical mediator release was reduced along with the activities of hydrolytic enzymes, e.g. NAG and cathepsin D with no evidence of lipid peroxidation and protective SOD enzyme activity elevation. The latter effects of the antibiotic would be useful in blocking the spread of infection or inflammation from the original site. The normal bacterial static killing effects of clarithromycin was evident at 24 but not 2 hr in both extracellular free bacteria and those bacteria phagocytosed by the THP-1 monocytes.
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PMID:Disposition and functions of clarithromycin in human THP-1 monocytes during stimulated and unstimulated conditions. 1276 Apr 88

This study characterizes 3 cases of mesenchymal chondrosarcoma (MC) utilizing a proteomic approach that allows for the detection, visual quantification, cellular compartmentalization, and assessment of the functional state of certain proteins that may promote tumor growth and/or oppose apoptosis. Immunohistochemical procedures were performed to detect the following protein antigens: CD99, interleukin (IL)-1alpha, IL-6, transforming growth factor (TGF)-alpha, conventional (c) protein kinase C (cPKC)-alpha, cPKC-betaII, phosphorylated (p)-PKC-alpha/betaII, c-kit (CD117), platelet-derived growth factor receptor (PDGFR)-alpha, PDGFR-beta, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor (HER)-2/neu, cathepsin D, angiotensin-converting enzyme (ACE), angiotensin II type 1 (AT1) receptor, p21ras, the alpha subunit of farnesyl and geranylgeranyl transferase (FTalpha/GGTalpha), phospho (p)-c-Jun N-terminal kinase (p-JNK), p-p38 mitogen-activated protein kinase (MAPK), cyclin D1, c-Jun, Ki-67, bcl-2, TGF-beta1 latency-associated peptide (LAP), TGF-betaRII, and cyclooxygenase (COX)-2. Immunoreactivities were scored from 0 to 3+ positivity using bright-field microscopy. The results showed that malignant mesenchymal chondroblasts exhibit stronger expressions of CD99, IL-1alpha, cPKC-alpha, p-PKC-alpha/betaII, PDGFR-alpha, p-JNK, Ki-67, and bcl-2 antigens than their more mature-appearing chondrocytic counterparts in MC. In conclusion, molecular profiling of mesenchymal chondrosarcoma using a proteomic approach characterized the mesenchymal chondroblasts as possessing pathways that incorporate PKC-alpha and PDGFR-alpha signaling and anti-apoptotic bcl-2 expression. Specific therapies to target the mesenchymal chondroblasts in mesenchymal chondrosarcoma might include interferon-alpha, rapamycin, ciprofloxacin, and STI571.
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PMID:Mesenchymal chondrosarcoma: molecular characterization by a proteomic approach, with morphogenic and therapeutic implications. 1281 16

The effects of grepafloxacin on the release of cytokines, chemical mediators, hydrolytic enzyme activities, and lipoxygenation in zymogen A- or Staphylococcus aureus-stimulated human THP-1 monocytes were evaluated. Initially, consistent with stimulation of phagocytic mechanisms of the monocytes, increases in cyclic adenosine monophosphate (cAMP) release, nitric oxide [NO] release, and hydrogen peroxide [H(2)O(2)] release, with a small decrease in cellular pH, occurred within 2 h. Enzymatic activities associated with oxygen burst of phagocytic cells (e.g., protein kinase C and nicotinamide adenine dinucleotide phosphate, reduced (NADPH) oxidase) were elevated, suggesting that monocytes attempted to destroy the invading organism through an innate phagocytic cidal immunologic mechanism. After 1-2 h of exposure to grepafloxacin, the oxygen burst and the release of proinflammatory cytokines and chemical mediators were suppressed. After 4 h, suppression of n-acetyl glucosaminidase (NAG) and cathepsin D activities and lipid peroxidation occurred, suppressing the pathogen-induced spread of infection and inflammation. Release of tumor necrosis factor (TNFalpha), interleukin (IL)-1, IL-6, and IL-8 was inhibited by grepafloxacin in a concentration-dependent manner, suggesting a reduction in the acute-phase inflammatory responses initiated by cytokine release from monocytes. Later, S. aureus were killed through inhibition of DNA synthesis, consistent with a bacteriostatic effect. Drug action against invading organisms appears to occur through multiple processes. Modulation of the innate immune system occurs within the first hour, causing the activation of cytokines, chemical mediators, and hydrolytic enzymes. A second phase between 2-4 h appears to involve the suppression of cellular components involved in inflammation and the spread of the infection. The third response, an apparent bacteriostatic inhibition of DNA synthesis, causes bacterial death.
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PMID:In-vitro anti-inflammatory and immunomodulatory effects of grepafloxacin in zymogen A- or Staphylococcus aureus-stimulated human THP-1 monocytes. 1282 12

Antimicrobial agents have been reported to exhibit immunomodulatory and anti-inflammatory activities, both in vivo and in vitro (e.g., in human lymphocytes, macrophages and monocytes). The effects of moxifloxacin on cytokine immunomodulatory mediators, free radical generation and hydrolytic enzyme activities in zymogen A-stimulated human THP-1 monocytes were evaluated. An increase in c-AMP levels, protein kinase C activity, and the release of nitric oxide and hydrogen peroxide with a decrease in pH occurred within the first hour. Further, the effects of moxifloxacin were reduced by agents which blocked the oxygen burst, lysosome-phagosome fusion, and the energy generation within the cell. After 4 h, there was a decrease in NAG and cathepsin D activities, lipid peroxidation and the release of pro-inflammatory cytokines. These data indicate that moxifloxacin may modify the acute-phase inflammatory responses through inhibition of cytokine release in monocytes. Moxifloxacin inhibited the release of TNFalpha, IL-1, IL-6, and IL-8 in a concentration-dependent manner across a range of 0.004 to 4 microg/mL. After 4 h, there was a decrease in the release of these cytokines, thus interfering with the inflammation process to reduce infection and its spread. The effects of moxifloxacin appear initially to activate monocytes to kill bacteria through the innate immune process by releasing ROS and lysosomal hydrolytic enzymes as well as phagocytosis of the organism. At a later time the bacteria are killed through a Bacterialstatic mechanism of protein synthesis inhibition and there is a reversal of the effects of moxifloxacin on cytokine release, free radical generation and hydrolytic enzymes so that lipid peroxidation and tissue destruction by the infection process is suppressed.
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PMID:Effects of moxifloxacin in zymogen A or S. aureus stimulated human THP-1 monocytes on the inflammatory process and the spread of infection. 1367 36

Acquisition of microbicidal properties by phagosomes requires the action of molecules which regulate the interactions between phagosomes and endocytic organelles. Members of the protein kinase C (PKC) superfamily of serine/threonine kinases are recruited to phagosomes with various kinetics during phagolysosome biogenesis. To study the role of PKC-alpha in this process, we compared the composition of latex bead-containing phagosomes isolated from control and dominant-negative (DN) PKC-alpha-overexpressing RAW 264.7 macrophages. Western blot analysis indicated that the levels of both lysosomal-associated membrane protein-1 and flotillin-1, which are acquired through interactions with late endosomes and lysosomes, are reduced in phagosomes from DN PKC-alpha-overexpressing macrophages. Proteomic characterization of latex bead-containing phagosomes revealed that recruitment of the small GTPase Rab7, cathepsin D, and cathepsin S is inhibited by DN PKC-alpha. Collectively, these data provide evidence that PKC-alpha plays a role in phagolysosome biogenesis, a critical process of the innate immune response against infections.
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PMID:Proteomic analysis reveals a role for protein kinase C-alpha in phagosome maturation. 1518 55

Cultured human THP-1 monocytes were exposed to serial concentrations of gemifloxacin over 4 h after pre-stimulation with zymogen A for 1 h or Staphylococcus aureus for 2 h. The following parameters were assessed: pH, phagocytosis, c-AMP, NO, TNFalpha, IL-1, IL-6, IL-8 and H2O2 levels, enzyme activities of protein kinase C, NADPH oxidase, SOD, gluthathion reductase, NAG and cathepsin D as well as lipid peroxidation. The reversiblity of these changes was determined in the presence of known blockers of the phagocytic process. The effects of gemifloxacin on DNA synthesis and killing of S. aureus was assessed in bacteria alone and in those bacteria phagocytosed by THP-1 monocytes over 24 h. Gemifloxacin in stimulated THP-1 monocytes over the first 30 min caused an increase in c-AMP, NO, H2O2 and TNFalpha levels and protein kinase C, NADPH oxidase, glutathione reductase, NAG and cathepsin D activities. The pH became more acidic and phagocytosis was stimulated. These parameters were reversed at 1 h and continued to decline until 4 h. Lipid peroxidation was at the highest levels at 1 h and IL-8 levels at 2 h. DNA synthesis and bacterial growth were suppressed at 2 h in both S. aureus alone and bacteria phagocytosed by THP-1 monocytes. These effects were at a higher magnitude at 24 h. Gemifloxacin initiates a phagocyticidal effect of THP-1 monocytes at an early time of 30 min which plays a role in killing bacteria but a higher magnitude of killing of bacteria occurs later by a standard static mechanism. This early action of gemifloxacin should decrease the spread of infection and the inflammatory response since the tissue destruction process was attenuated at 4 h.
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PMID:In vitro anti-inflammatory effects and immunomodulation by gemifloxacin in stimulated human THP-1 monocytes. 1549 55


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