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

---

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

We investigated the intracellular route of Salmonella in macrophages to determine a plausible mechanism for their survival in phagocytes. Western blot analysis of isolated phagosomes using specific antibodies revealed that by 5 min after internalization dead Salmonella-containing phagosomes acquire transferrin receptors (a marker for early endosomes), whereas by 30 min the dead bacteria are found in vesicles carrying the late endosomal markers cation-dependent mannose 6-phosphate receptors, Rab7 and Rab9. In contrast, live Salmonella-containing phagosomes (LSP) retain a significant amount of Rab5 and transferrin receptor until 30 min, selectively deplete Rab7 and Rab9, and never acquire mannose 6-phosphate receptors even 90 min after internalization. Retention of Rab5 and Rab18 and selective depletion of Rab7 and Rab9 presumably enable the LSP to avoid transport to lysosomes through late endosomes. The presence of immature cathepsin D (48 kDa) and selective depletion of the vacuolar ATPase in LSP presumably contributes to the less acidic pH of LSP. In contrast, proteolytically processed cathepsin D (M(r) 17,000) was detected by 30 min on the dead Salmonella-containing phagosomes. Morphological analysis also revealed that after uptake by macrophages, the dead Salmonella are transported to lysosomes, whereas the live bacteria persist in compartments that avoid fusion with lysosomes, indicating that live Salmonella bypass the normal endocytic route targeted to lysosomes and mature in a specialized compartment.
...
PMID:Live Salmonella modulate expression of Rab proteins to persist in a specialized compartment and escape transport to lysosomes. 1082 69

Chinese hamster ovary (CHO) cell mutants defective in the disintegration of endocytosed low-density lipoprotein (LDL) were isolated from mutagenized cells by repeated flow-cytometric cell sorting. After seven rounds of cell sorting, we obtained mutant pools, from which nine mutant clones were established. These mutant strains were all recessive, and were categorized into three complementation groups A, B, and C. The previously established CHO mutant, LEX1 (Lysosome-Endosome X1), fell into the complementation group A. One of the newly isolated mutants, LEX2, fell into the complementation group B, and showed slower degradation of RET-LDL than LEX1 cells. LEX2 showed prominence of well-elaborated multivesicular bodies (MVBs), positive for lysosomal glycoprotein-B/cathepsin D and cation-independent mannose 6-phosphate receptor (CI-MPR), yet negative for transferrin receptor or rab7. Endocytosed intact LDL accumulated in these CI-MPR-positive structures starting at 10-15 minutes of internalization and the accumulation reached completion at 20 minutes. Intermixing of separately internalized fluorescent LDLs between the LEX2 MVBs was slow and saturable at a lower level than observed between late endosomes/lysosomes in wild-type or in LEX1 cells. The receptor recycling pathway to the plasma membrane and the acidification of intracellular compartments were normal in LEX2 cells. These results are consistent with the idea that LEX2 cells are defective in the segregation and sequestration of contents at compartments equivalent to the transport intermediates, previously referred to as endosomal carrier vesicles or maturing MVBs. This MVB stage is likely to be an earlier stage than rab7-positive, lysosome-interacting late endosomes observed in LEX1 cells. Thus, LEX1 and LEX2 mutations could be considered as landmarks for these distinct late endocytic stages, and use of these cells in biochemical and molecular genetic analyses would help to understand the as yet unidentified details of late endocytic pathways including the MVB dynamics.
...
PMID:Arrested maturing multivesicular endosomes observed in a Chinese hamster ovary cell mutant, LEX2, isolated by repeated flow-cytometric cell sorting. 1082 92

Bordetella pertussis is readily killed after uptake by professional phagocytes, whereas its close relative Bordetella bronchiseptica is not and can persist intracellularly for days. Phagocytosis of members of either species by a mouse macrophage cell line results in transport of the bacteria to a phagosomal compartment positive for the lysosome-associated membrane protein 1, the protease cathepsin D, and the late endosomal vacuolar proton-pumping ATPase but negative for the early endosome antigen 1 and the early endosomal transferrin receptor. In addition, we demonstrate that Bordetella-containing phagosomes rapidly acidify to pH 4.5 to 5.0. Taken together, these data demonstrate that Bordetella-containing phagosomes rapidly mature to an acidic late endosomal/lysosomal compartment. Following up on this observation, we determined that B. pertussis does not survive in bacterial growth media adjusted to a pH of 4.5, whereas this pH has only minor effects on the growth of B. bronchiseptica. Raising the intracellular pH in infected macrophages by the addition of bafilomycin A(1), ammonium chloride, or monensin increases the survival of acid-sensitive B. pertussis but, surprisingly, decreases that of acid-tolerant B. bronchiseptica. In summary, we hypothesize that the differential survival of B. pertussis and B. bronchiseptica in macrophages is, at least in part, due to the differences in their acid tolerance.
...
PMID:Phagosome acidification has opposite effects on intracellular survival of Bordetella pertussis and B. bronchiseptica. 1108 29

Legionella pneumophila survives within macrophages by evading phagosome-lysosome fusion. To determine whether L. pneumophila resides in an intermediate endosomal compartment or is isolated from the endosomal pathway and to investigate what bacterial factors contribute to establishment of its vacuole, we applied a series of fluorescence microscopy assays. The majority of vacuoles, aged 2.5 min to 4 h containing post-exponential phase (PE) L. pneumophila, appeared to be separate from the endosomal pathway, as judged by the absence of transferrin receptor, LAMP-1, cathepsin D and each of four fluorescent probes used to label the endocytic pathway either before or after infection. In contrast, more than 70% of phagosomes that contained Escherichia coli, polystyrene beads, or exponential phase (E) L. pneumophila matured to phagolysosomes, as judged by co-localization with LAMP-1, cathepsin D and fluorescent endosomal probes. Surprisingly, neither bacterial viability nor the putative Dot/Icm transport complex was absolutely required for vacuole isolation; although phagosomes containing either formalin-killed PE wild-type or live PE dotA or dotB mutant L. pneumophila rapidly accumulated LAMP-1, less than 20% acquired lysosomal cathepsin D or fluorescent endosomal probes. Therefore, a Dot-dependent factor(s) isolates the L. pneumophila phagosome from a LAMP-1-containing compartment, and a formalin-resistant Dot-independent activity inhibits vacuolar accumulation of endocytosed material and delivery to the degradative lysosomes.
...
PMID:Evidence that Dot-dependent and -independent factors isolate the Legionella pneumophila phagosome from the endocytic network in mouse macrophages. 1120 24

Afipia felis is a Gram-negative bacterium that causes some cases of human Cat Scratch Disease. A. felis can survive and multiply in several mammalian cell types, including macrophages, but the precise intracellular compartmentalization of A. felis-containing phagosomes is unknown. Here, we demonstrate that, in murine macrophages, most A. felis-containing phagosomes exclude lysosomal tracer loaded into macrophage lysosomes before, as well as endocytic tracer loaded after, establishment of an infection. Established Afipia-containing phagosomes possess neither early endosomal marker proteins [early endosome antigen 1 (EEA1), Rab5, transferrin receptor, trytophane aspartate containing coat protein (TACO)] nor late endosomal or lysosomal proteins [cathepsin D, beta-glucuronidase, vacuolar proton-pumping ATPase, rab7, mannose-6-phosphate receptor, vesicle-associated membrane protein 8, lysosome-associated membrane proteins LAMP-1 and LAMP-2]. Those bacteria that will be found in a nonendosomal compartment enter the macrophage via an EEA1-negative compartment, which remains negative for LAMP-1. The smaller subpopulation of afipiae whose phagosomes will be part of the endocytic system enters into an EEA1-positive compartment, which also subsequently acquires LAMP-1. Killing of Afipia or opsonization with immune antibodies leads to a strong increase in the percentage of A. felis-containing phagosomes that interact with the endocytic system. We conclude that most phagosomes containing A. felis are disconnected from the endosome-lysosome continuum, that their unusual compartmentalization is decided at uptake, and that this compartmentalization requires bacterial viability.
...
PMID:Afipia felis induces uptake by macrophages directly into a nonendocytic compartment. 1140 61

Aspergillus fumigatus is the most prevalent airborne fungal pathogen responsible for fatal invasive aspergillosis in immunocompromised patients. Upon arrival in the lung alveolus, conidia of A. fumigatus are phagocytosed by alveolar macrophages, the major phagocytic cells of the lung. Engulfment and intracellular trafficking of A. fumigatus conidia in alveolar macrophages of two different origins, the murine cell line MH-S and human pulmonary alveolar macrophages, were analyzed by electron microscopy and immunofluorescence. Phagocytosis of A. fumigatus conidia required actin polymerization and phosphatidylinositol 3-kinase activity. Fusion of A. fumigatus phagosomes with early and late endosomes was shown by immunolabeling with specific markers for the transferrin receptor, early endosome antigen, and Rab7. Maturation of A. fumigatus phagolysosomes was monitored by using a fixable acidotropic probe, LysoTracker Red DND-99, and an anti-cathepsin D antibody. Bafilomycin A-induced inhibition of lysosomal acidification abolished the conidial killing by the macrophages. These data suggest that the maturation of A. fumigatus phagosomes results from fusion with the compartments of the endocytic pathway and that the killing of conidia depends on phagolysosome acidification. A model for the phagocytosis of A. fumigatus conidia by alveolar macrophages is proposed on the basis of these results.
...
PMID:Phagocytosis and intracellular fate of Aspergillus fumigatus conidia in alveolar macrophages. 1254 May 71

Small GTPase RhoA regulates signal transduction from receptors in the membrane to a variety of cellular events related to cell morphology, motility, cytoskeletal dynamics, cytokinesis, and tumour progression, but it is unclear how RhoA regulates intracellular membrane dynamics of lysosomes. We showed previously by confocal immunofluorescence microscopy that the transfection of dominant active RhoA in MM1 cells causes the dispersal translocation of lysosomes stained for cathepsin D throughout the cytoplasm. Y-27632, a selective inhibitor of p160ROCK, impeded the cellular redistribution of lysosomes and promoted reclustering of lysosomes toward the perinuclear region. Here we have further investigated whether the acidic lysosomal vesicles dispersed throughout the cytoplasm are applied to the early endosomes in the endocytic pathway, and we demonstrate that the dispersed lysosomes were accessible to endocytosed molecule such as dextran, and their acidity was not changed, as determined by increased accumulation of the acidotropic probe LysoTracker Red. Brefeldin A did not induce the tabulation of these dispersed lysosomes, but it caused early endosomes to form an extensive tubular network. The dispersed lysosomes associated with cathepsin D and LIMPII were not colocalized with early endosomes, and these vesicles were not inaccessible to the endocytosed anti-transferrin receptor antibody. Moreover, wortmannin, an inhibitor of phosphatidylinositol 3-kinase, induced a dramatic change in LIMPII-containing structures in which LIMPII-positive swollen large vacuoles were increased and small punctate structures disappeared in the cytoplasm. These swollen vacuoles were not doubly positive for LIMPII and transferrin receptor, and were not inaccessible to the internalized anti-transferrin receptor antibody. Therefore, our novel findings presented in this paper indicate that RhoA activity causes a selective translocation of lysosomes without perturbing the machinery of endocytic pathway.
...
PMID:A role for small GTPase RhoA in regulating intracellular membrane traffic of lysosomes in invasive rat hepatoma cells. 1258 97

Escherichia coli K1 has been shown to invade human brain microvascular endothelial cells (HBMEC) in vitro and translocate the blood-brain barrier in vivo, but it is unclear how E. coli K1 traverses HBMEC. We have previously shown that internalized E. coli K1 is localized within membrane-bound vacuole in HBMEC. The present study was carried out to understand intracellular trafficking of E. coli K1 containing vacuoles (ECVs) in HBMEC. ECVs initially acquired two early endosomal marker proteins, EEA1 and transferrin receptor. Rab7 and Lamp-1, markers for late endosome and late endosome/lysosome, respectively, were subsequently recruited on the ECVs, which was confirmed with flow cytometry analysis of ECVs. However, ECVs did not obtain cathepsin D, a lysosomal enzyme, even after 120 min incubation, suggesting that E. coli K1 avoids lysosomal fusion. In contrast, isogenic K1 capsule-deletion mutant obtained early and late endosomal markers on vacuolar membranes and allowed lysosomal fusion with subsequent degradation inside vacuoles. This observation was consistent with the decreased intracellular survival of K1 capsule-deletion mutant, even though the binding and internalization rates of the mutant were higher than those of the parent E. coli K1 strain. This is the first demonstration that E. coli K1, via the K1 capsule on the bacterial surface, modulates the maturation process of ECVs and prevents fusion with lysosomes, which is an event necessary for traversal of the blood-brain barrier as live bacteria.
...
PMID:The K1 capsule modulates trafficking of E. coli-containing vacuoles and enhances intracellular bacterial survival in human brain microvascular endothelial cells. 1267 82

LIM kinase (LIMK) plays a critical role in stimulus-induced remodeling of the actin cytoskeleton by linking signals from the Rho family GTPases to changes in cofilin activity. Recent studies have shown an important role for LIMK1 signaling in tumor cell invasion through regulating actin dynamics. In this study, we investigate the role of LIMK1 in intracellular vesicle trafficking of lysosomes/endosomes. We analyzed by confocal immunofluorescence microscopy the cellular distribution of lysosomal proteins and the endocytosis of an endocytic tracer, epidermal growth factor (EGF), in LIMK1-transfected cells. We found in these cells an abnormal dispersed translocation of lysosomes stained for LIMPII and cathepsin D throughout the cytoplasm. The small punctate structures that stained for these lysosomal proteins were redistributed to the periphery of the cell. Computational 3D-image analysis of confocal immunofluorescence micrographs further demonstrated that these vesicles did not colocalize with the transferrin receptor, an early endosomal marker. Furthermore, LIMPII-positive lysosomes did not colocalize with early endosomes labeled with endocytosed Texas red-transferrin. These results indicate that there is no mixing between dispersed lysosomes and early endosomes in the LIMK1-transfected cells. Moreover, LIMK1 overexpression resulted in a marked retardation in the receptor-mediated internalization of Texas red-labeled EGF in comparison with mock-transfected cells. At 30 min after internalization, most of the Texas red-EGF staining overlapped with LIMPII-positive late endosomes/lysosomes in mock-transfected cells, whereas in LIMK1 transfectants only a small fraction of internalized EGF colocalized with LIMPII-positive structures in the perinuclear region. Taken together, the findings presented in this paper suggest that LIMK1 has a role in regulating vesicle trafficking of lysosomes and endosomes in invasive tumor cells.
...
PMID:LIM kinase 1: evidence for a role in the regulation of intracellular vesicle trafficking of lysosomes and endosomes in human breast cancer cells. 1550 60

Ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) are currently under development for the intracellular delivery of therapeutics. However, the mechanisms of cellular uptake and the cellular reaction to this uptake, independent of therapeutics, are not well defined. The interactions of biocompatible cationic aminoUSPIONs with human cells was studied in 2D and 3D cultures using biochemical and electron microscopy techniques. AminoUSPIONs were internalized by human melanoma cells in 2D and 3D cultures. Uptake was clathrin mediated and the particles localized in lysosomes, inducing activation of the lysosomal cathepsin D and decreasing the expression of the transferrin receptor in human melanoma cells and/or skin fibroblasts. AminoUSPIONs deeply invaded 3D spheroids of human melanoma cells. Thus, aminoUSPIONs can invade tumors and their uptake by human cells induces cell reaction.
...
PMID:Interaction of cationic ultrasmall superparamagnetic iron oxide nanoparticles with human melanoma cells. 2087 22


<< Previous 1 2 3 Next >>

---