Disease relevance of LOC396026

• When chicken occludin was overexpressed in insect cells by recombinant baculovirus infection, peculiar multilamellar structures accumulated in the cytoplasm [1].

High impact information on LOC396026

• COOH terminus of occludin is required for tight junction barrier function in early Xenopus embryos [2].
• Importantly, our data show that tight junctions containing four of the COOH-terminally truncated occludin proteins were leaky; the intercellular spaces between the apical cells were penetrated by sulfosuccinimidyl-6-(biotinamido) Hexanoate (NHS-LC-biotin) [2].
• Nevertheless, expression of both wild-type and mutant occludin induced increased transepithelial electrical resistance (TER) [3].
• Additionally, the C-terminal domain of occludin was also able to mediate endocytosis [4].
• To test whether the basolateral membrane is an obligatory intermediate in transport of occludin to tight junctions, we analyzed the expression of occludin molecules rendered unable to efficiently integrate into tight junctions by the introduction of N-linked glycosylation sites into the two extracellular loops [4].

Biological context of LOC396026

• However, nothing is known about the identity of specific occludin kinase(s) and occludin phosphorylation site(s) [5].
• Biogenesis of tight junctions: the C-terminal domain of occludin mediates basolateral targeting [4].

Anatomical context of LOC396026

• Occludin: a novel integral membrane protein localizing at tight junctions [6].
• Occludin is a protein component of the membrane domain of tight junctions, and has been shown to be phosphorylated in vivo in cultured cells and Xenopus laevis embryos [5].
• Chick occludin was detectable by western blot within two hours of adding isopropyl- beta-D-thiogalactoside to monolayers that had previously achieved steady state transepithelial electrical resistance; this coincided with focal immunofluorescence staining for chick occludin at the cell membrane of some cells [7].
• Here we demonstrate the presence of the major tight junction protein occludin in granulosa cells [8].
• The possible roles of occludin in the developing gastrointestinal tract are discussed [9].

Associations of LOC396026 with chemical compounds

• Once steady state transepithelial electrical resistance was achieved, isopropyl- beta-D-thiogalactoside was added to induce chick occludin expression [7].
• Two days after plating confluent monolayers that were induced to express chick occludin, mannitol flux was reduced to a variable degree relative to control monolayers [7].
• Under supplementation with DMSO, immunofluorescently demonstrable occludin and ZO-1 were induced progressively at cell borders in parallel with the increase in TER that occurred with decreases in inulin and dextran permeability [10].
• The existence of a blood-brain barrier is demonstrated by the exclusion of intravascularly injected tracer (horseradish peroxidase), and immunocytochemical demonstration of glucose transporter-1 as a functional marker and of neurothelin, occludin and ZO-1 as structural markers [11].

Other interactions of LOC396026

• While densitometric analysis of western blots indicated that the presence of chick occludin had no detectable effect on E-cadherin or ZO-1 expression, the possibility cannot be excluded that ZO-1 might be a limiting factor in the expression of chick occludin at the cell surface [7].
• By immunocytochemistry, the tight junction (TJ) proteins occludin and claudin-1 were localized in the periderm and in the subperiderm, and sites of close contact between adjacent cells were detected by electron microscopy [12].
• With the onset of barrier differentiation as determined by junctional restriction of the tight junction protein occludin, N-cadherin labelling rapidly decreased [13].

Analytical, diagnostic and therapeutic context of LOC396026

• This rearrangement of occludin was not paralleled by apparent changes in the junctional morphology as seen by thin section electron microscopy nor apparent discontinuities of the junctional strands observed by freeze-fracture [3].
• Confocal immunofluorescence and immunoelectron microscopy demonstrated that mutant occludin was incorporated into tight junctions but, in contrast to full-length chicken occludin, exhibited a discontinuous junctional staining pattern and also disrupted the continuous junctional ring formed by endogenous occludin [3].
• Immunoprecipitation analysis of detergent-solubilized embryo membranes revealed that the exogenous occludin was bound to endogenous Xenopus occludin in vivo, indicating that occludin oligomerized during tight junction assembly [2].
• Upon removal of isopropyl- beta-D-thiogalactoside chick occludin expression declined slowly until it was no longer detected in western blots 72 hours later; transepithelial electrical resistance also returned to baseline values during this time [7].
• Confocal laser scanning microscopy of monolayers immunolabeled with Oc-2 monoclonal antibody revealed that chick occludin localized precisely to the preformed tight junctions [7].

References