Loosening tight junctions. Lessons from the intestine.

Madara, James L.

doi:10.1172/jci113987

Cited by 312 publications

(134 citation statements)

References 56 publications

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“…The jejunum (beginning 10 cm distal to the Treitz ligament) was removed, rinsed with cold saline, and mounted in the Ussing chamber, as previously described (Li et al, 1989). (Madara, 1989 (Cornell et al, 1971;Warshaw et al, 1974;Heyman et al, 1982;Marcon-Genty et al, 1989). In the present study, the rate of j3-LG absorption through rat jejunum in vitro, as determined by transfer of radioactive material, was slightly higher than that previously reported for rabbit ileum (Marcon-Genty et al, 1989).…”

contrasting

confidence: 55%

“…In the present study, we observed reduced tissue conductance and short-circuit current, and decreased (i-LG absorption in vitro by lactose-fed rat jejunum, compared to the control. Tissue conductance is known to reflect ion permeation through tight junctions (Madara, 1989), and it has been previously observed that G decreases with cell turnover. Therefore, one could assume that lactose-feeding of adult rats results in reduced leakiness of the intestinal epithelium, and that this is a possible consequence of the previously described slowdown of epithelial cell turn-over (Meslin et al, 1981 Lactase activity of the intestinal mucosa of adult rats is low and lactose is known to be poorly absorbed in the small intestine (Kim et al, 1978).…”

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confidence: 99%

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In vitro transport of β-lactoglobulin across the jejunum of lactose-fed rats

Jf¹,

Tomé²

1990

Reprod. Nutr. Dévelop.

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Summary ― Changes in protein absorption through the intestinal mucosa occur with aging and might reflect modifications in enterocyte membrane characteristics. We have observed that bovine [3-lactoglobulin (P-LG) was efficiently transported across the small intestine of adult rats in vitro and that 12-16% of the absorbed protein was recovered intact or as large hydrophobic peptides. Ten percent lactose-feeding resulted in decreased tissue conductance and significantly reduced (-58%, P < 0.05) j3-LG transport across rat small intestinal mucosa. The amounts of j3-LG absorbed, either as amino acids and peptides or as intact protein, were reduced to the same extent. Therefore, the effect of lactose feeding might be related to a decrease in protein endocytosis at the brush-border level, rather than to reduced protein transport across tight junctions. intestine / (3-lactoglobulin / lactose / transport / rat

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contrasting

confidence: 55%

mentioning

confidence: 99%

In vitro transport of β-lactoglobulin across the jejunum of lactose-fed rats

Jf¹,

Tomé²

1990

Reprod. Nutr. Dévelop.

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“…The intestinal epithelial barrier consists of apical plasma membrane of the enterocytes that acts as a transcellular barrier and intercellular tight junctions (TJs) that act as a paracellular barrier against intercellular penetration of toxic luminal substances, including bacterial endotoxins, bacterial by-products, digestive enzymes, and food-degradation products. [1][2][3][4][5][6] The TJ complex consists of cytoplasmic and transmembrane proteins. The transmembrane proteins, which include occludin, claudin family of proteins, and junctional adhesion molecules, extend from cytoplasmic compartment across the plasma membrane into extracellular compartment to participate in the formation of an extracellular TJ seal.…”

mentioning

confidence: 99%

Cellular and Molecular Mechanisms of Heat Stress-Induced Up-Regulation of Occludin Protein Expression

Dokładny

Kennedy

et al. 2008

The American Journal of Pathology

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The heat stress (HS)-induced increase in occludin protein expression has been postulated to be a protective response against HS-induced disruption of the intestinal epithelial tight junction barrier. The aim of this study was to elucidate the cellular and molecular processes that mediate the HS-induced up-regulation of occludin expression in Caco-2 cells. Exposure to HS (39°C or 41°C) resulted in increased expression of occludin protein; this was preceded by an increase in occludin mRNA transcription and promoter activity. HS-induced activation of heat shock factor-1 (HSF-1) resulted in cytoplasmic-to-nuclear translocation of HSF-1 and binding to its binding motif in the occludin promoter region. HSF-1 activation was associated with an increase in occludin promoter activity, mRNA transcription, and protein expression; which were abolished by the HSF-1 inhibitor quercetin. Targeted The intestinal epithelial barrier consists of apical plasma membrane of the enterocytes that acts as a transcellular barrier and intercellular tight junctions (TJs) that act as a paracellular barrier against intercellular penetration of toxic luminal substances, including bacterial endotoxins, bacterial by-products, digestive enzymes, and food-degradation products.1-6 The TJ complex consists of cytoplasmic and transmembrane proteins. The transmembrane proteins, which include occludin, claudin family of proteins, and junctional adhesion molecules, extend from cytoplasmic compartment across the plasma membrane into extracellular compartment to participate in the formation of an extracellular TJ seal.7-10 The critical role of transmembrane proteins in the formation and maintenance of the TJ barrier is well established; however, the precise protein structure and components and molecular determinants of TJ barrier remain unclear. 11Occludin is an integral transmembrane TJ protein that has been shown to play a crucial role in TJ barrier function and TJ signaling process. Previous studies have shown that overexpression of occludin protein in MDCK cells leads to an enhancement of TJ barrier function. 12Conversely, siRNA knock-down of occludin leads to an increase in TJ permeability to selected paracellular markers. 13 Molecular studies have shown that COOH-terminal end of occludin plays a crucial role in the maintenance of paracellular barrier function.14 Additionally, biochemical alteration of occludin phosphorylation has been shown to be an important determinant of TJ localization of occludin protein and enhancement of TJ barrier function.

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“…the tight junction. 14) Low molecular weight drugs with high water-solubility can easily pass through the lipid bilayer membrane of the enterocytes. Although LMWH is a highly water-soluble drug, it cannot pass through such membrane pores due to its relatively large molecular weight (5500 Da) and potent negative charges.…”

Section: Discussionmentioning

confidence: 99%