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  • COMPLEX  (6)
  • 1
    Keywords: CELLS ; Germany ; PROTEIN ; PROTEINS ; METABOLISM ; desmosome ; COMPLEX ; COMPLEXES ; MESSENGER-RNA ; FAMILY ; BINDING ; PARTICLES ; IDENTIFICATION ; NUMBER ; STRESS ; EPITHELIAL-CELLS ; INVOLVEMENT ; OXIDATIVE STRESS ; INITIATION ; JUNCTIONS ; RE ; DESMOSOMAL PLAQUE ; TRANSLATION ; INTERCELLULAR-JUNCTIONS ; PLAQUE PROTEINS ; BAND-6 PROTEIN ; MENTAL-RETARDATION PROTEIN ; P120 CATENIN ; PROCESSING BODIES ; TRANSLATION INITIATION
    Abstract: Recent studies on the subcellular distribution of cytoplasmic plaque proteins of intercellular junctions have revealed that a number of such proteins can also occur in the cyto- and the nucleoplasm. This occurrence in different, and distant locations suggest that some plaque proteins play roles in cytoplasmic and nuclear processes in addition to their involvement in cell-cell adhesive interactions. Plakophilin (PKP) 3, a member of the arm-repeat family of proteins, occurs, in a diversity of cell types, both as an architectural component in plaques of desmosomes and dispersed in cytoplasmic particles. In immuno-selection experiments using PKP3-specific antibodies, we have identified by mass spectrometric analysis the following RNA-binding proteins: Poly (A) binding protein (PABPC1), fragile-X-related protein (FXR1), and ras-GAP-SH3-binding protein (G3BP). Moreover, the RNA-binding proteins codistributed after sucrose gradient centrifugation in PKP3-containing fractions corresponding to 25-35 S and 45-55 S. When cells are exposed to environmental stress (e.g., heat shock or oxidative stress) proteins FXR1, G3BP, and PABPC1 are found, together with PKP3 or PKP1, in "stress granules" known to accumulate stalled translation initiation complexes. Moreover, the protein eIF-4E and the ribosomal protein S6 are also detected in PKP3 particles. Our results show that cytoplasmic PKP3 is constitutively associated with RNA-binding proteins and indicate an involvement in processes of translation and RNA metabolism
    Type of Publication: Journal article published
    PubMed ID: 16407409
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  • 2
    Keywords: brain ; DISTINCT ; GENES ; PROTEIN ; COMPLEX ; antibodies ; ARRANGEMENT ; ALPHA-TUBULIN ; ANCIENT EUKARYOTE ; BETA-TUBULIN ; cytoskeleton ; DIVERSITY ; Giardia lamblia ; immunocytochemistry ; MICROTUBULES ; POLYGLYCYLATION ; SUPERFAMILY ; TRYPANOSOMA-BRUCEI ; tubulin
    Abstract: Giardia lamblia is a diplomonad that parasitizes the small intestine of vertebrates. The trophozoite is multiflagellar and its cytoskeleton presents a complex organization of microtubular structures. One of these, the adhesive disk, consists of a microtubular spiral. The median body, whose function is not yet determined, is also composed by microtubules. The cell has eight flagella and two microtubule sheets, known as the funis. In this study we used several antibodies and immunofluorescence microscopy to help in the characterization of these structures. We observed that Giardia tubulin reacts with antibodies raised against very distinct immunogens. The antibodies used were against: (1) alpha-tubulin from chicken embryo brain, Trypanosoma brucei, sea urchin sperm, Paramecium, acetylated alpha-tubulin from Paramecium, and tyrosinated alpha-tubulin, (2) beta-tubulin from chicken embryo brain and Physarum polycephalum, and (3) an antibody with specificity to beta-tubulin having as immunogen the FtsZ bacterial protein. Each cytoskeletal structure of Giardia presented a distinct pattern of labeling by the several antibodies used. These data indicate that even being considered one of the most ancient of organisms, Giardia shares similarities (at least in relation to tubulin) with other organisms. They also open some questions about the organization and composition of its microtubular structures
    Type of Publication: Journal article published
    PubMed ID: 12687378
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  • 3
    Keywords: CELLS ; IN-VITRO ; SYSTEM ; PROTEIN ; COMPLEX ; ENRICHMENT ; DYNAMICS ; NERVOUS-SYSTEM ; immunohistochemistry ; FIBROBLAST-GROWTH-FACTOR ; ACTIN-BINDING-PROTEIN ; CD2-ASSOCIATED PROTEIN ; CONGENITAL NEPHROTIC SYNDROME ; CONTRACTILE PROTEINS ; DENDRITIC SPINES ; FOCAL SEGMENTAL GLOMERULOSCLEROSIS ; INTERMEDIATE FILAMENT PROTEINS ; SLIT DIAPHRAGM ; ULTRASTRUCTURAL ORGANIZATION
    Abstract: Drebrins are actin-binding proteins (ABP) initially identified in and thought to be specific for neuronal cells, where they appear to contribute to the formation of cell processes. Recent studies have also detected the isoform drebrin E2 in a wide range of non-neuronal cell types, notably in and near actin- rich lamellipodia and filopodia. The present study demonstrates drebrin enrichment in renal glomeruli. Immunohistochemistry and double-label confocal laser scanning microscopy have shown intense drebrin reactions in the mesangial cells of diverse mammalian species. In adult human and bovine kidneys, drebrin is, in addition, markedly enriched in the foot processes of podocytes, as also demonstrable by immunoelectron microscopy. By contrast, the podocytes of rodent glomeruli appear to contain significant drebrin concentrations only during early developmental stages. In differentiated murine podocytes cultured in vitro, however, drebrin is concentrated in the cell processes, where it partially codistributes with actin and other ABP. In biochemical analyses using protein extracts from renal cortices, large (approximately 20S) complexes ("drebrosomes") were found containing drebrin and actin. These findings confirm and extend our hypothesis that drebrin is involved in the regulation of actin dynamics also outside the nervous system. Clearly, drebrin has to be added to the ensemble of ABP regulating the actomyosin system and the dynamics of mesangial cells and foot processes in podocytes
    Type of Publication: Journal article published
    PubMed ID: 12761245
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  • 4
    Keywords: CANCER ; CELLS ; GROWTH ; GROWTH-FACTOR ; tumor ; carcinoma ; Germany ; human ; MICROSCOPY ; DIAGNOSIS ; PROTEIN ; PROTEINS ; TUMORS ; COMPLEX ; COMPLEXES ; INDUCTION ; KERATINOCYTES ; SKIN ; ASSOCIATION ; immunohistochemistry ; skin cancer ; CARCINOMA-CELLS ; LOCALIZATION ; ADHESION ; intermediate filaments ; CARCINOMAS ; INVOLVEMENT ; squamous cell carcinoma ; beta-catenin ; epidermis ; human hair follicle ; HUMAN EPIDERMIS ; SKIN-CANCER ; CATENIN ; basal cell carcinoma ; HUMAN SKIN ; EPIDERMAL-GROWTH-FACTOR ; INNER-ROOT-SHEATH ; RE ; keratinocyte ; TUMORIGENESIS ; HAIR FOLLICLE ; SKIN CANCERS ; cell adhesion ; hair ; INTERCELLULAR-JUNCTIONS ; BCC ; DESMOSOMAL PLAQUE PROTEINS ; ADHERENS JUNCTIONS ; CELL-CARCINOMA ; E-CADHERIN EXPRESSION ; actin-binding protein ; INTERCELLULAR-ADHESION
    Abstract: Isoform E2 of drebrin, an actin-binding protein originally identified in neuronal cells, has recently been identified in diverse non-neuronal cells, mostly in association with cell processes and intercellular junctions. Here, we report on the presence of drebrin in normal human skin, epithelial skin cancers, and cultured keratinocytes. Keratinocytes of normal epidermis contain almost no drebrin but the protein is readily seen in hair follicles. By immunohistochemistry and immunoblot, basal cell carcinomas (BCC) are rich in drebrin, and confocal laser scanning and immunoelectron microscopy show accumulation at adhering junctions, in co-localization with actin and partially with plaque proteins. In squamous cell carcinomas, keratoacanthomas, and in epidermal precancers, drebrin is heterogeneously distributed, appearing as mosaics. Primary keratinocyte cultures contain significant amounts of drebrin enriched at adhering junctions. When epithelium-derived cells devoid of drebrin are transfected with drebrin-enhanced green fluorescent protein, constructs accumulate in the cell periphery, and immunoprecipitation shows complexes with actin. During epidermal growth factor induced formation of cell processes, drebrin retains this junction association, as observed by live cell microscopy. Our results suggest novel functions of drebrin such as an involvement in cell-cell adhesion and tumorigenesis and a potential value in diagnosis of BCC
    Type of Publication: Journal article published
    PubMed ID: 16185277
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  • 5
    Keywords: APOPTOSIS ; CELLS ; EXPRESSION ; GROWTH ; INVASION ; tumor ; carcinoma ; IN-VIVO ; GENE ; GENE-EXPRESSION ; COMPLEX ; COMPLEXES ; DOMAIN ; INDUCTION ; cell cycle ; CELL-CYCLE ; CYCLE ; ALPHA ; antibodies ; antibody ; PROGRESSION ; gene expression ; SUBUNIT ; PLASMA ; MEMBRANE ; TUMOR PROGRESSION ; METASTASIS ; SIGNALING PATHWAYS ; CANCER-CELLS ; EXTRACELLULAR-MATRIX ; BETA ; LOCALIZATION ; ADHESION ; MIGRATION ; TRANSFORMATION ; PLASMA-MEMBRANE ; EPITHELIAL-CELLS ; INTEGRIN ; SUBUNITS ; GROWTH-FACTOR-BETA ; Ras ; ALPHA-6-BETA-4 INTEGRIN ; FACTOR-BETA ; MATRIX ; PROGRAM ; RE ; collagen ; extracellular matrix ; TRANSITION ; TGF-BETA ; EPITHELIAL-MESENCHYMAL TRANSITIONS ; plasma membrane ; MOLECULAR-MECHANISMS ; TGF beta ; EXTRACELLULAR-MATRIX PROTEINS ; laminin ; EMT ; fibronectin receptor ; laminin receptor
    Abstract: In nontumorigenic mammary epithelial cells (EpH4), transforming growth factor-beta (TGF beta 1) causes cell cycle arrest/apoptosis, but induces epitheliomesenchymal transition (EMT) in Ha-Ras-transformed EpH4 cells (EpRas). EMT is closely correlated with late-stage tumor progression and results in fibroblastic, migratory cells displaying a mesenchymal gene expression program (FibRas). EpRas and FibRas cells showed strongly increased cell substrate adhesion to fibronectin, collagens I/IV and laminin 1. Furthermore, Ras transformation caused enhanced or de-novo expression of the integrin subunits beta 1, alpha 2 and alpha 3, or alpha 5 and alpha 6, respectively, the latter subunits being even more strongly expressed in FibRas cells. Importantly, polarized EpRas cells expressed integrin subunits beta 1 and beta 6 at distinct (apical and lateral) membrane domains, while FibRas cells coexpressed these integrins and alpha 5 at the entire plasma membrane. During EMT, EpRas cells formed an alpha 5 beta 1 complex and deposited its ligand fibronectin into the extracellular matrix. Function-blocking alpha 5 antibodies attenuated migration, and caused massive apoptosis in EpRas cells undergoing TGF beta 1-induced EMT in collagen gels, but failed to affect EpRas- or FibRas-derived structures. We conclude that functional alpha 5b1 integrin is centrally implicated in EMT induction. Importantly, FibRas cells also failed to deposit the alpha 6 beta 4 ligand laminin 5, suggesting that alpha 6 beta 4 is no longer functional after EMT and replaced by mesenchymal integrins such as alpha 5 beta 1
    Type of Publication: Journal article published
    PubMed ID: 15688013
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  • 6
    Keywords: APOPTOSIS ; CELLS ; Germany ; human ; POPULATION ; DISTINCT ; PROTEIN ; PROTEINS ; COMPLEX ; COMPLEXES ; REDUCTION ; STAGE ; mass spectrometry ; FUSION ; MASS-SPECTROMETRY ; POPULATIONS ; INTERACTS ; HEAT-SHOCK PROTEINS ; CHROMOSOMES ; RE ; HELA-CELLS ; LEVEL ; PERSISTENCE ; CHAPERONE ; function ; ESSENTIAL COMPONENT ; PROGRESS ; AURORA KINASES ; Poles ; CENP-E ; CYSTEINE-STRING PROTEIN ; misaligned chromosomes ; prometaphase arrest ; REACTION CYCLE ; REPEAT-CONTAINING PROTEIN ; TPR-CONTAINING PROTEIN
    Abstract: The human small glutamine-rich TPR-containing protein (hSGT) is essential for cell division since RNA-interference-mediated strong reduction of hSGT protein levels causes mitotic arrest (M. Winnefeld, J. Rommelaere, and C. Cziepluch, The human small glutamine-rich TPR-containing protein is required for progress through cell division, Exp. Cell Res. 293 (2004), 43-57). Analysis of HeLa cells expressing a histone 2A-YFP fusion protein revealed the continuous presence of few mislocalized chromosomes close to the spindle poles as possible cause for hSGT depletion-dependent prometaphase arrest. Cells unable to rescue these mislocalized chromosomes into the metaphase plate died at this stage through apoptosis. in order to address hSGT function at the molecular level, mass spectrometry analysis of proteins which co-immunoprecipitated with Flag-tagged hSGT was performed. Thereby, Hsp70 and Bag-6/Bat-3/Scythe were identified as novel hSGT interaction partners while interaction with Hsc70 was confirmed. Results obtained with truncated versions of the hSGT protein revealed that Bag-6/Bat-3/Scythe and Hsp70 or Hsc70 were independently able to form complexes with hSGT. Interaction of hSGT with Hsc70, Hsp70 or Bag-6/Bat-3/Scythe was demonstrated in prometaphase, thereby suggesting a possible role for complexes containing hSGT and distinct (co)-chaperones during mitosis. Finally, cells from populations with reduced levels of Bag-6/Bat-3/Scythe also displayed persistence of mislocalized chromosomes and mitotic arrest, which strongly indicated that hSGT-Bag-6/Bat-3/Scythe complexes could be directly or indirectly required for complete chromosome congression. (c) 2006 Elsevier Inc. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 16777091
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