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  • 1
    Keywords: DESMOSOMAL PLAQUE PROTEINS ; ADHERENS JUNCTIONS ; N-CADHERIN ; SERTOLI-CELL ; POSTNATAL-DEVELOPMENT ; MALE CONTRACEPTIVE DEVELOPMENT ; RAT TESTIS ; ECTOPLASMIC SPECIALIZATION ; BARRIER DYNAMICS ; CYTOSKELETAL PROTEINS
    Abstract: The seminiferous tubules and the excurrent ducts of the mammalian testis are physiologically separated from the mesenchymal tissues and the blood and lymph system by a special structural barrier to paracellular translocations of molecules and particles: the "blood-testis barrier", formed by junctions connecting Sertoli cells with each other and with spermatogonial cells. In combined biochemical as well as light and electron microscopical studies we systematically determine the molecules located in the adhering junctions of adult mammalian (human, bovine, porcine, murine, i.e., rat and mouse) testis. We show that the seminiferous epithelium does not contain desmosomes, or "desmosome-like" junctions, nor any of the desmosome-specific marker molecules and that the adhering junctions of tubules and ductules are fundamentally different. While the ductules contain classical epithelial cell layers with E-cadherin-based adherens junctions (AJs) and typical desmosomes, the Sertoli cells of the tubules lack desmosomes and "desmosome-like" junctions but are connected by morphologically different forms of AJs. These junctions are based on N-cadherin anchored in cytoplasmic plaques, which in some subforms appear thick and dense but in other subforms contain only scarce and loosely arranged plaque structures formed by alpha- and beta-catenin, proteins p120, p0071 and plakoglobin, together with a member of the striatin family and also, in rodents, the proteins ZO-1 and myozap. These N-cadherin-based AJs also include two novel types of junctions: the "areae adhaerentes", i.e., variously-sized, often very large cell-cell contacts and small sieve-plate-like AJs perforated by cytoplasm-to-cytoplasm channels of 5-7 nm internal diameter ("cribelliform junctions"). We emphasize the unique character of this epithelium that totally lacks major epithelial marker molecules and structures such as keratin filaments and desmosomal elements as well as EpCAM- and PERP-containing junctions. We also discuss the nature, development and possible functions of these junctions.
    Type of Publication: Journal article published
    PubMed ID: 24907851
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  • 2
    Keywords: ANGIOGENESIS ; CELLS ; ENDOTHELIAL-CELLS ; IN-VITRO ; BLOOD ; Germany ; human ; IN-VIVO ; VITRO ; SYSTEM ; PROTEIN ; PROTEINS ; desmoplakin ; TISSUE ; COMPLEX ; COMPLEXES ; TISSUES ; beta-catenin ; TIGHT JUNCTIONS ; rodent ; JUNCTIONS ; LYMPHATIC ENDOTHELIUM ; RE ; DESMOSOMAL PLAQUE ; INTERCELLULAR-JUNCTIONS ; DESMOSOMAL PLAQUE PROTEINS ; SIZE ; ADHERENS JUNCTIONS ; BOVINE ; function ; lymph node ; LYMPH-NODE ; N-CADHERIN ; adhering junction ; VE-CADHERIN ; BLOOD-BRAIN-BARRIER ; Complexus adhaerens ; DESMOPLAKIN-CONTAINING JUNCTIONS ; HUMAN GLIOBLASTOMA-MULTIFORME ; retothelium ; TO-CELL JUNCTIONS
    Abstract: The significance of a special kind of VE-cadherin-based, desmoplakin- and plakoglobin-containing adhering junction, originally identified in certain endothelial cells of the mammalian lymphatic system ( notably the retothelial cells of the lymph node sinus and a subtype of lining endothelial cells of peripheral lymphatic vessels), has been widely confirmed and its importance in the formation of blood and lymph vessels has been demonstrated in vivo and in vitro. We have recently extended the molecular and structural characterization of the complexus adhaerens and can now report that it represents a rare and special combination of components known from three other major types of cell junction. It comprises zonula adhaerens proteins (VE-cadherin, alpha- and beta-catenin, protein p120(ctn), and afadin), desmosomal plaque components ( desmoplakin and plakoglobin), and tight-junction proteins (claudin-5 and ZO-1) and forms junctions that vary markedly in size and shape. The special character and the possible biological roles of the complexus adhaerens and its unique ensemble of molecules in angiogenesis, immunology, and oncology are discussed. The surprising finding of claudin-5 and protein ZO-1 in substructures of retothelial cell-cell bridges, i.e., structures that do not separate different tissues or cell layer compartments,suggests that such tight-junction molecules are involved in functions other than the "fence" and "barrier" roles of zonulae occludentes
    Type of Publication: Journal article published
    PubMed ID: 16372193
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  • 3
    Keywords: INTERMEDIATE-SIZED FILAMENTS ; STRATIFIED EPITHELIA ; DESMOSOMAL PLAQUE PROTEINS ; ADHERENS JUNCTIONS ; Area composita ; HEART-MUSCLE CELLS ; Molecular composition ; INTERCELLULAR ADHERING JUNCTIONS ; TARGET GENE PERP ; HUMAN-EPIDERMIS
    Abstract: Protein PERP (p53 apoptosis effector related to PMP-22) is a small (21.4 kDa) transmembrane polypeptide with an amino acid sequence indicative of a tetraspanin character. It is enriched in the plasma membrane and apparently contributes to cell-cell contacts. Hitherto, it has been reported to be exclusively a component of desmosomes of some stratified epithelia. However, by using a series of newly generated mono- and polyclonal antibodies, we show that protein PERP is not only present in all kinds of stratified epithelia but also occurs in simple, columnar, complex and transitional epithelia, in various types of squamous metaplasia and epithelium-derived tumors, in diverse epithelium-derived cell cultures and in myocardial tissue. Immunofluorescence and immunoelectron microscopy allow us to localize PERP predominantly in small intradesmosomal locations and in variously sized, junction-like peri- and interdesmosomal regions ("tessellate junctions"), mostly in mosaic or amalgamated combinations with other molecules believed, to date, to be exclusive components of tight and adherens junctions. In the heart, PERP is a major component of the composite junctions of the intercalated disks connecting cardiomyocytes. Finally, protein PERP is a cobblestone-like general component of special plasma membrane regions such as the bile canaliculi of liver and subapical-to-lateral zones of diverse columnar epithelia and upper urothelial cell layers. We discuss possible organizational and architectonic functions of protein PERP and its potential value as an immunohistochemical diagnostic marker.
    Type of Publication: Journal article published
    PubMed ID: 23689684
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