Search results for "Desmosome"

Aging changes of the ciliary epithelium border layers and their significance for intraocular pressure.

1971

Intermediate filaments and desmosomal plaque proteins in testicular seminomas and non-seminomatous germ cell tumours as revealed by immunohistochemis…

1987

Seminomas and non-seminomatous testicular germ cell tumours were studied for the presence of cytokeratin and vimentin filaments and desmosomes using immunohistochemical methods. In the majority of the classical seminomas and in seminomatous areas of mixed tumours most tumour cells appeared to lack cytokeratin filaments. Some seminomas contained a focally variable proportion of cells exhibiting cytokeratin-positive structures while other cases contained only few seminoma cells with a well developed fibrillar cytokeratin network. Gel electrophoresis of cytoskeletal proteins from microdissected regions revealed cytokeratin polypeptides nos. 8 and 18 typical of simple epithelia. In one seminoma…

Structural and regulatory functions of keratins.

2007

The diversity of epithelial functions is reflected by the expression of distinct keratin pairs that are responsible to protect epithelial cells against mechanical stress and to act as signaling platforms. The keratin cytoskeleton integrates these functions by forming a supracellular scaffold that connects at desmosomal cell-cell adhesions. Multiple human diseases and murine knockouts in which the integrity of this system is destroyed testify to its importance as a mechanical stabilizer in certain epithelia. Yet, surprisingly little is known about the precise mechanisms responsible for assembly and disease pathology. In addition to these structural aspects of keratin function, experimental e…

The cell adhesion domain of type XVII collagen promotes integrin-mediated cell spreading by a novel mechanism.

2001

Type XVII collagen (BP180) is a keratinocyte transmembrane protein that exists as the full-length protein in hemidesmosomes and as a 120-kDa shed ectodomain in the extracellular matrix. The largest collagenous domain of type XVII collagen, COL15, has been described previously as a cell adhesion domain (Tasanen, K., Eble, J. A., Aumailley, M., Schumann, H., Baetge, J, Tu, H., Bruckner, P., and Bruckner-Tuderman, L. (2000) J. Biol. Chem. 275, 3093-3099). In the present work, the integrin binding of triple helical, human recombinant COL15 was tested. Solid phase binding assays using recombinant integrin alpha(1)I, alpha(2)I, and alpha(10)I domains and cell spreading assays with alpha(1)beta(1)…

Tumor dedifferentiation: an important step in tumor invasion.

1985

Tumor invasion in vivo was studied by light and electron microscopy as well as by immunofluorescence microscopy. Special regard was paid to the grade of tumor differentiation. Dimethylhydrazine-induced murine colonic carcinomas comprising a differentiated and an undifferentiated tumor type with low and high invasiveness respectively, were used. At the invasion front of both tumor types a striking dissociation of the organized tumor cell complexes into isolated tumor cells was found together with a loss of most of the cytological features of differentiation. It is supposed that this process mobilizes the tumor cells from the main tumor bulk enabling them to invade the host tissue by active l…

Intermediate filament protein profiles of human testicular non-seminomatous germ cell tumors: correlation of cytokeratin synthesis to cell differenti…

1991

Abstract The patterns of cytoskeletal differentiation were studied in 20 testicular non-seminomatous germ cell tumors by immunohistochemistry, using diverse monoclonal antibodies specific for different intermediate filament (IF) proteins and for desmoplakin. Immuno-fluorescence and immunoperoxidase methods on both formalin-fixed and frozen tissues were applied, in some cases together with a gel electrophoretic analysis of IF proteins. The tumors examined included embryonal carcinoma (EC), endodermal sinus tumor (EST), choriocar-cinoma and teratoma. Nine of the tumors were composed of only one histological type, the others showed mixed components. Cytokeratins 8 and 18 were identified in all…

Electron microscopic observations on primary hepatocyte cultures infected with herpes simplex virus Types I and II

1984

The replication cycle of the Herpes simplex virus (HSV) strains I and II has so far been described mainly in established proliferative cell cultures. Most of the biochemical data and ultrastructural cell changes regarding the virus-cell interaction have been obtained from ‘permissive’ cells which allow almost unrestricted viral multiplication. It seems obvious, however, that the in vivo viral infections are not represented adequately by these experiments. In order to achieve a more realistic view of the ultrastructural events during HSV infection of adult tissue, cell cultures were prepared from adult mouse and rat livers and infected with several HSV strains. Established ‘permissive’ cell …

Loss of desmoglein 2 suggests essential functions for early embryonic development and proliferation of embryonal stem cells.

2002

Summary Desmoglein 2 (Dsg2) is a Ca 2+ -dependent adhesion molecule of desmosomes and is synthesized in all desmosome-bearing tissues from their earliest appearance onward. To examine the function of Dsg2, its gene was inactivated by homologous recombination in embryonal stem (ES) cells for the generation of knockout mice. DSG2 −/− mice and a considerable number of DSG2 +/− mice died at or shortly after implantation. On the other hand, DSG2 −/− blastocysts developed an apparently normal trophectoderm layer, the first tissue known to produce desmosomes, and hatched properly. Immunofluorescence analyses of these blastocysts showed, however, that the distribution of the desmosomal plaque prote…

Ultrastructural changes of the intercellular relationship in impaired human spermatogenesis

1980

In seven hypo- or aspermic patients, electron microscopic investigations of the intercellular connections of the seminiferous tubule were performed. The analysis of cell junctions of Sertoli cells and germ cells revealed irregularities of the Sertoli-cell junctions, hypoplasias of occluding junctions, hypo- and hyperplasias of the Sertoli-spermatid cell junctions and abnormal formation of Sertoli cell junctions with early spermatids, spermatocytes, and spermatogonia. Gap junction-like cell membrane specializations were very rare. Intercellular cytoplasmic bridges of germ cells were always present together with these cells. One hypoplastic bridge connecting two spermatogonia was found. The r…

Desmosomes: interconnected calcium-dependent structures of remarkable stability with significant integral membrane protein turnover

2002

Desmosomes are prominent cell adhesion structures that are major stabilizing elements, together with the attached cytoskeletal intermediate filament network, of the cytokeratin type in epithelial tissues. To examine desmosome dynamics in tightly coupled cells and in situations of decreased adhesion, fluorescent desmosomal cadherin desmocollin 2a (Dsc2a) chimeras were stably expressed in human hepatocellular carcinoma-derived PLC cells (clone PDc-13) and in Madin-Darby canine kidney cells (clone MDc-2) for the continuous monitoring of desmosomes in living cells. The hybrid polypeptides integrated specifically and without disturbance into normal-appearing desmosomes that occurred in associati…