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  • 1
    Keywords: CELLS ; proliferation ; carcinoma ; Germany ; MICROSCOPY ; GENE-EXPRESSION ; PROTEIN ; PROTEINS ; DIFFERENTIATION ; MONOCLONAL-ANTIBODY ; DOMAIN ; antibodies ; antibody ; MOUSE ; MEMBRANE ; MONOCLONAL-ANTIBODIES ; PHENOTYPE ; PERIPHERAL-BLOOD ; BARRIER FUNCTION ; PERMEABILITY ; CYTOKERATINS ; HETEROGENEITY ; SINGLE ; immunofluorescence ; monoclonal antibody ; BOVINE ; EPITHELIUM ; IA ; ASYMMETRIC UNIT MEMBRANE ; MAMMALIAN URINARY-BLADDER ; PLAQUE PARTICLE ; UROPATHOGENIC ESCHERICHIA-COLI ; uroplakins ; urothelium
    Abstract: Urothelial umbrella cells are characterized by apical, rigid membrane plaques, which contain four major uroplakin proteins (UP la, Ib, II and III) forming UPla/UPII and UPIb/UPIII pairs. These integral membrane proteins are thought to play an important role in maintaining the physical integrity and the permeability barrier function of the urothelium. We asked whether the four uroplakins always coexpress in the entire human lower urinary tract. We stained immunohistochemically (ABC-peroxidase method) paraffin sections of normal human ureter (n = 18) and urinary bladder (n = 10) using rabbit antibodies against UPIa, UPIb,. UPII and UPIII; a recently raised mouse monoclonal antibody (MAb), AU1 and two new MAbs, AU2 and AU3, all against UPHIII; and mouse MAbs against umbrella cell-associated cytokeratins CK18 and CK20. Immunoblotting showed that AU1, AU2 and AU3 antibodies all recognized the N-terminal extracellular domain of bovine UPIII. By immunochemistry, we found that in 15 cases of human ureter, but in only 2 18 TO cases of bladder, groups of normal-looking, CK18-positive umbrella cells lacked both UPIII and UPIb immunostaining. The UPIb/UPIII-negative cells showed either normal or reduced amounts of UPla and UPII staining. These data were confirmed by double immunofluorescence microscopy. The distribution of the UPlb/UPIII-negative umbrella cells was not correlated with localized urothelial proliferation (Ki-67 staining) or with the distribution pattern of CK20. Similar heterogeneities were observed in bovine but not in mouse ureter. We provide the first evidence that urothelial umbrella cells are heterogeneous as some normal-looking umbrella cells can possess only one, instead of two, uroplakin pairs. This heterogeneity seems more prominent in the urothelium Of human ureter than that of bladder. This finding may indicate that ureter urothelium is intrinsically different from bladder urothelium. Alternatively, a single lineage of urothelium may exhibit different phenotypes resulting from extrinsic modulations due to distinct mesenchymal influence and different degrees of pressure and stretch in bladder versus ureter. Additional studies are needed to distinguish these two possibilities and to elucidate the physiological and pathological significance of the observed urothelial and uroplakin heterogeneity. (c) 2005 Elsevier GmbH. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 15819416
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  • 2
    Keywords: CELLS ; CELL ; CELL-PROLIFERATION ; Germany ; GENERATION ; DISTINCT ; PROTEIN ; PROTEINS ; COMPONENTS ; MONOCLONAL-ANTIBODY ; BIOLOGY ; antibodies ; antibody ; PARTICLES ; IDENTIFICATION ; SPECTROMETRY ; REGION ; REGIONS ; XENOPUS ; MONOCLONAL-ANTIBODIES ; DNA-REPLICATION ; REPLICATION ; CLUSTER ; XENOPUS-LAEVIS ; WERNER-SYNDROME PROTEIN ; AMPLIFIED NUCLEOLI ; DESMOSOMAL PLAQUE ; NUCLEAR LAMINA PROTEINS ; NUCLEOPLASMIN FAMILY ; RIBOSOME BIOGENESIS
    Abstract: It has recently become clear that the nucleolus, the most prominent nuclear subcompartment, harbors diverse functions beyond its classic role in ribosome biogenesis. To gain insight into nucleolar functions, we have purified amplified nucleoli from Xenopus laevis oocytes using a novel approach involving fluorescence-activated cell sorting techniques. The resulting protein fraction was analyzed by mass spectrometry and used for the generation of monoclonal antibodies directed against nucleolar components. Here, we report the identification and molecular characterization of a novel, ubiquitous protein, which in most cell types appears to be a constitutive nucleolar component. Immunolocalization studies have revealed that this protein, termed NO66, is highly conserved during evolution and shows in most cells analyzed a dual localization pattern, i.e., a strong enrichment in the granular part of nucleoli and in distinct nucleoplasmic entities. Colocalizations with proteins Ki-67, HP1alpha, and PCNA, respectively, have further shown that the staining pattern of NO66 overlaps with certain clusters of late replicating chromatin. Biochemical experiments have revealed that protein NO66 cofractionates with large preribosomal particles but is absent from cytoplasmic ribosomes. We propose that in addition to its role in ribosome biogenesis protein NO66 has functions in the replication or remodeling of certain heterochromatic regions
    Type of Publication: Journal article published
    PubMed ID: 14742713
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  • 3
  • 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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