Adherent junctions

Tight junctions form selective barriers that regulate paracellular transport across epithelia and endothelia. Tight junctions are composed of transmembrane proteins (occludin, claudins, and JAMs) linked to the actin cytoskeleton through cytoplasmic ZO proteins, whereas adherence junctions are composed of the nectin-afadin system and the E-cadhcrin catenin system [143]. These cell cell adhesion proteins create the barrier and regulate electrical resistance, size, and ionic charge selectivity [144], Several experimental procedures have... 

The calcium chelators such as EDTA have been reported to loosen the tight junctions between the superficial epithelial cells, thus facilitating paracellular transport [31,32]. The Ca2+ depletion does not act directly on the tight junctions rather it induces global changes in the cells, including (1) the disruption of actin filaments, (2) the disruption of adherent junctions, (3) diminished cell adhesion of actin filaments, and (4) the activation of protein kinases [33]. 

The adherent junctions are ubiquitously found in the cerebral vasculature and mediate several functions, including the adhesion of endothelial cells to each other, contact inhibition during remodeling, and growth of the vasculature, and mediate in part the regulation of paracellular permeability (Hawkins and Davis, 2005). The most important components of the adherent junctions are vascular endothelial... 

VE)-cadherin and platelet endothelial cell adhesion molecule-1 (PECAM-1). VE-cadherin is an endothelial-specific Ca " -regulated protein that is linked to the cytoskeleton via catenins (Fig. 1). PECAM-1, also known as CD31, is a key participant in the migration of blood-borne cells across the BBB. Changes in the adherent junction proteins can lead to increased paracellular permeability (Abbruscato and Davis, 1999) and leukocyte trafficking in the CNS (Newman, 1994 Garrido-Urbani et al., 2008). 

Epithelial cadherin (E-cadherin) has a molecular weight of 130 kDa and is found in PNS myelin. E-cadherin is a protein of the superfamily of calcium-dependent cell adhesion molecules that can usually form adherent junctions. This protein has an N-terminal extracellular domain, a short transmembrane domain and a C-terminal intracellular domain. 

The desmosomal junction is a morphological entity that is very distinct from adherence junctions involving classical cadherins [44]. The plasma membrane domains of apposing cells are separated by a 20-30 nm thick layer, which in cross section in electron micrographs reveals a midline structure and electron-dense threads stretching laterally from the midline back to the plasma membrane. The cytoplasmic face of each membrane domain is covered with an electron-dense plaque to which bundles of intermediate filaments attach, rather than the actin filaments present in adherence junctions containing classical cadherins. In most epithelia the intermediate filaments are based on keratins but rarer examples of desmosomal junctions coupled into intermediate filaments of the vimentin or desmin type are known [5]. 

Polyimide friction. The friction of polymers consists of an adhesion component and a deformation component. The adhesion component arises from the shearing of adhered junctions and is usually modeled as the product of the real area of contact and the shear strength of the polymer. The deformation component arises from the frictional work required to balance the energy dissipated in plastic deformation. Some Investigators have developed friction models in which the adhesive bonds at the junctions Increase the amount of plastic deformation over that which would exist in the absence of these bonds (13). 

Influences the interaction of cells of the preimplantation mammalian embryo May couple the morphogenic effects of adhesion and synaptic activity-dependent processes In bone formation, may mediate the interaction of osteoblasts and regulate skeletogenesis May mediate the formation of fiber cell gap junctions and adherence junction during lens cell differentiation... 

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