The Integral Role of Tight Junction Proteins in the Repair of Injured Intestinal Epithelium

Abstract

The intestinal epithelial monolayer forms a transcellular and paracellular barrier that separates luminal contents from the interstitium. The paracellular barrier consists of a highly organized complex of intercellular junctions that is primarily regulated by apical tight junction proteins and tight junction-associated proteins. This homeostatic barrier can be lost through a multitude of injurious events that cause the disruption of the tight junction complex. Acute repair after injury leading to the reestablishment of the tight junction barrier is crucial for the return of both barrier function as well as other cellular functions, including water regulation and nutrient absorption. This review provides an overview of the tight junction complex components and how they link to other plasmalemmal proteins, such as ion channels and transporters, to induce tight junction closure during repair of acute injury. Understanding the components of interepithelial tight junctions and the mechanisms of tight junction regulation after injury is crucial for developing future therapeutic targets for patients experiencing dysregulated intestinal permeability.

Bioactive Polyphenols from Pomegranate Juice Reduce 5-Fluorouracil-Induced Intestinal Mucositis in Intestinal Epithelial Cells

“…In conditions of intestinal epithelium injury, as during mucositis, detachment of the epithelium from the basement membrane and separation of adjacent epithelial cells due to dysregulation and loss of TJs occurs. Closure of the tight junction after acute intestinal injury is a predominant aspect in restoring barrier function and homeostatic functioning [61]. In particular, down regulation of claudin-1, occludin and ZO-1 contributes to increased intestinal permeability that results in cell polarity loss, [62].…”

The Link between Oral and Gut Microbiota in Inflammatory Bowel Disease and a Synopsis of Potential Salivary Biomarkers

“…Generally, the small intestine has a relatively low density and diversity of microbiota colonizers due to frequent disruption of digestive secretions such as bile and vary depending on oxygen and nutrient availability [60]. The major functions of the large intestine are to absorb and synthesize vitamins, absorb electrolytes and water via osmosis and electrochemical gradients, and to aid in the elimination of indigestible material [61]. Like much of the GI tract, the large intestine is made up of several layers including the mucosa layer, submucosa, muscle layer, and serosa, from the lumen out.…”

Intestinal Barrier Breakdown and Mucosal Microbiota Disturbance in Neuromyelitis Optical Spectrum Disorders

“…Epithelial cells join together tightly by different types of intercellular junctions such as TJs, AJs, and desmosomes ( 50 , 51 ). Additionally, gap junction proteins such as OCC, CLA, and ZO-1 are important in maintaining the integrity of the intestinal epithelium.…”

“…Additionally, gap junction proteins such as OCC, CLA, and ZO-1 are important in maintaining the integrity of the intestinal epithelium. Defects in ZO-1, OCC, and CLA expression may lead to abnormal intestinal mucosal barrier permeability by increasing paracellular permeability ( 50 , 52 ). In the present study, we analyzed three types of gap junction proteins (OCC, CLA, and ZO-1), and the results showed that the levels of these proteins were significantly decreased in NMOSD patients.…”