The Experts below are selected from a list of 1038 Experts worldwide ranked by ideXlab platform
Robert D. Goldman - One of the best experts on this subject based on the ideXlab platform.
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Insights into the mechanical properties of epithelial cells: the effects of shear stress on the assembly and remodeling of keratin intermediate filaments
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2009Co-Authors: Eric W. Flitney, Edward R. Kuczmarski, Stephen A. Adam, Robert D. GoldmanAbstract:The effects of shear stress on the keratin intermediate filament (KIF) cytoskeleton of cultured human alveolar epithelial (A549) cells have been investigated. Under normal culture conditions, immunofluorescence revealed a delicate network of fine Tonofibrils containing KIFs, together with many nonfilamentous, keratin-containing "particles," mostly containing either keratin 8 (K8) or 18 (K18), but not both. Triton X-100 extracted approximately 10% of the cellular keratin, and this was accompanied by a loss of the particles but not the KIFs. Shear stress dramatically reduced the soluble keratin component and transformed the fine bundles of KIFs into thicker, "wavy" Tonofibrils. Both effects were accompanied by the disappearance of most keratin particles and by increased phosphorylation of K8 and K18 on serine residues 73 and 33, respectively. The particles that remained after shearing were phosphorylated and were closely associated with KIFs. We suggest that keratin particles constitute a reservoir of protein that can be recruited into KIFs under flow, creating a more robust cytoskeleton able to withstand shear forces more effectively.
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Insights into the dynamic properties of keratin intermediate filaments in living epithelial cells.
The Journal of cell biology, 2001Co-Authors: Kyeong Han Yoon, Miri Yoon, Robert D. Moir, Satya Khuon, Frederick W. Flitney, Robert D. GoldmanAbstract:The properties of keratin intermediate filaments (IFs) have been studied after transfection with green fluorescent protein (GFP)-tagged K18 and/or K8 (type I/II IF proteins). GFP-K8 and -K18 become incorporated into Tonofibrils, which are comprised of bundles of keratin IFs. These Tonofibrils exhibit a remarkably wide range of motile and dynamic activities. Fluorescence recovery after photobleaching (FRAP) analyses show that they recover their fluorescence slowly with a recovery t 1/2 of ∼100 min. The movements of bleach zones during recovery show that closely spaced Tonofibrils (
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A transglutaminase-related antigen associates with keratin filaments in some mouse epidermal cells.
The Journal of investigative dermatology, 1997Co-Authors: Sophie Clement, Amy V. Trejo-skalli, Pauline T. Velasco, Laszlo Lorand, Robert D. GoldmanAbstract:A mouse monoclonal IgG, G82, directed against guinea pig liver transglutaminase recognizes a transglutaminase-related antigen that is associated with the keratin intermediate filament network in some primary mouse keratinocytes. The association can be seen at the resolution of individual keratin Tonofibrils following fixation and staining for double-label indirect immunofluorescence. Western blots indicate that G82 reacts with two proteins of 95kDa and 280kDa, respectively, in extracts of these cells. The 95-kDa band is also recognized by a polyclonal antibody against purified guinea pig liver transglutaminase, and the 280-kDa protein seems to correspond to a similar protein that was shown to be recognized by G92.1.2 in the intermediate filament fraction of primary mouse fibroblasts. The transglutaminase-related antigen was shown by confocal microscopy to co-localize only with nonbasal cell specific keratin intermediate filaments.
Paolo Romagnoli - One of the best experts on this subject based on the ideXlab platform.
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Human keratinocytes cultured without a feeder layer undergo progressive loss of differentiation markers.
Histology and histopathology, 1999Co-Authors: Francesca Prignano, L. Domenici, Gianni Gerlini, Nicola Pimpinelli, Paolo RomagnoliAbstract:Culture of keratinocytes in conventional medium without a mesenchyme-derived feeder layer leads to poor growth and impaired differentiation; however, the exact pathway and degree of differentiation achieved in such conditions is unclear. We have cultured normal human keratinocytes in Rheinwald and Green's medium, on plastic without a feeder layer, in order to investigate the degree of differentiation that they achieve in these conditions. Intermediate filament proteins, Tonofibrils and desmosomes were assumed as markers of differentiation and their expression was analyzed by immunohistochemistry and electron micros~opy. Before reaching confluence, keratinocytes expressed keratin molecules, as well as vimentin, and formed Tonofibrils and desmosomes. The expression of these markers was progressively reduced until confluence and was totally lost thereafter, while cultures could be propagated for at least six passages. On the contrary, reseeding on a feeder layer after the first passage led to rapid cell death. It could be concluded that signals from a feeder layer are relevant to support continuous synthesis of intermediate filaments proteins and formation of tonofibils and desmosomes, and that the derangement of the cytoskeleton in these conditions leads to altered, not simply defective, response to delayed stimulation by a feeder layer.
Shin-ichi Iwasaki - One of the best experts on this subject based on the ideXlab platform.
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Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa
The Anatomical record, 1996Co-Authors: Shin-ichi Iwasaki, Tomoichiro Asami, Chaitip WanichanonAbstract:Background Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. Methods The light microscope, scanning electron microscope and transmission electron microscope were used. Results Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, Tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the Tonofibrils and tonofilaments, was clearly distinguishable. Conclusions The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.© 1996 Wiley-Liss, Inc.
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Fine structure of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus.
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft, 1992Co-Authors: Shin-ichi IwasakiAbstract:Summary Light and electron microscopic observations of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus , revealed three different regions: the epithelium on the anterior side of the filiform papillae, the epithelium on the posterior side of the filiform papillae, and the interpapillar epithelium. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules appear predominantly in the intermediate layer of the epithelium on the anterior side of filiform papillae. In the epithelium on the posterior side of the filiform papillae, no keratohyalin granules are seen and, instead, Tonofibrils are prominent. The cells begin to be sigificantly flattened. In the interpapillar epithelium, no keratohyalin granules and Tonofibrils are seen, and the tonofilaments occupy almost the entire cytoplasm of the cells of the intermediate and surface layers, with the cells having larger volumes in these layers.
Chaitip Wanichanon - One of the best experts on this subject based on the ideXlab platform.
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Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa
The Anatomical record, 1996Co-Authors: Shin-ichi Iwasaki, Tomoichiro Asami, Chaitip WanichanonAbstract:Background Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. Methods The light microscope, scanning electron microscope and transmission electron microscope were used. Results Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, Tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the Tonofibrils and tonofilaments, was clearly distinguishable. Conclusions The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.© 1996 Wiley-Liss, Inc.
K Miyata - One of the best experts on this subject based on the ideXlab platform.
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Fine structure of the dorsal epithelium of the mongoose tongue.
Journal of anatomy, 1990Co-Authors: S Iwasaki, K MiyataAbstract:The epithelium of the lingual dorsum of the mongoose, Herpestes edwardsi, was composed of two main areas: the interpapillary area, characterised by the absence of keratinisation; and the papillary area, characterised by hard keratinisation. The number of Tonofibrils in the cytoplasm gradually increased, and the volume of the individual cells also increased, from the germinal layer to the intermediate layer of the interpapillary epithelium. No keratohyalin granules were recognised in these cells. In the cells of the surface layer of the interpapillary epithelium, most of the cytoplasm was filled with tonofilaments. The germinal layer of the papillary epithelium was almost identical to that of the interpapillary epithelium. In the intermediate layer, three different types of keratohyalin granule were apparent. The first type consisted of loosely aggregated ribosomes and had moderate electron density. The second type consisted of electron-dense granules derived from granules of the first type. The third type consisted of conjugated structures made up of Tonofibrils, which were embedded in electron-dense material. Free ribosomes gradually disappeared as the keratinised layer was approached and most of the cytoplasm of cells in this layer was filled with keratin fibres.
