• Applied Microscopy
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• v.25 no.2
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• pp.53-64
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• 1995

This study was designed to investigate the morphological alterations of zonula occludens, macula adherences and gap junctions between the hepatocytes in the fasting conditions. Animals (Sprague Dawley, $250{\sim}280g$) were divided into two groups: normal and fasting. The latter were fasted for eight days prior to sampling. Liver tissues were sectioned and replicated after freeze fracturing for the transmission electron microscopy. In the normal rat liver, the interhepatocellular space at the area of some zonula occludens appeared to be widened in thin sections. On the freeze fracture replicas., the zonula occludens appeared as an anastomosing network of $2{\sim}4$ strands or grooves on P or E faces. Free ends and fragments of the strands were observed. In the rat fasted for eight days, the hepatocytes were diminished in size and the organelles were decreased in number and size. The intercellular space was wide at many areas of zonula occludens in thin section. On the freeze fracture replicas, the zonula occludens showed diminution or disappearence of anastomosing network of strands or grooves. Free ends and small fragments of the strands or grooves were frequently encountered. The macula adherens was markedly increased in number in thin sections, although they could not be found on the freeze fracture replicas. The gap junctions were increased in number in thin sections. Small aggregations of the intramembranous particles appeared with larger ones on the freeze fracture replica. The evidences may suggest the followings: (1) The disassembly of zonula occludens in the fasting states is led from the diminished mechanical stress on the luminal surface of bile canaliculus with the impaired secretion of bile components from the hepatocytes. (2) The increase of macula adherens is necessary to maintain the liver parenchyma integrity in the fasting state which leads the hepatocyte to be diminished and finally the intercellular space to be separated. (3) The rise in both number and size of gap junctions is owing to the need of increasing intercellular communication between the hepatocytes during the fasting. (4) The alteration of zonula occludens is easily led by the physiological condition of hepatocytes even in the normal ones.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.580-586
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• 2014

Intestinal epithelial cells (IECs) forming the barrier for the first-line of protection are interconnected by tight junction (TJ) proteins. TJ alteration results in impaired barrier function, which causes potentially excessive inflammation leading to intestinal disorders. It has been suggested that toll-like receptor (TLR) 2 ligands and some bacteria enhance epithelial barrier function in humans and mice. However, no such study has yet to be claimed in swine. The aim of the present study was to examine whether Bacillus subtilis could improve barrier integrity and protection against deoxynivalenol (DON)-induced barrier disruption in porcine intestinal epithelial cell line (IPEC-J2). We found that B. subtilis decreased permeability of TJ and improved the expression of zonula occludens (ZO)-1 and occludin during the process of forming TJ. In addition, ZO-1 expression of IPEC-J2 cells treated with B. subtilis was up-regulated against DON-induced damage. In conclusion, B. subtilis may have potential to enhance epithelial barrier function and to prevent the cells from DON-induced barrier dysfunction.

• Journal of Animal Science and Technology
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• v.64 no.3
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• pp.500-514
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• 2022

The blood-epididymis barrier (BEB) forms a unique microenvironment that is crucial for the maturation, protection, transport, and storage of spermatozoa in the epididymis. To characterize the function of tight junctions (TJs), which are constitutive components of the BEB, we determined the expression and localization of TJ proteins such as zonula occludens (ZO)-1, 2, and 3, occludin, and claudin3 (Cldn3) during postnatal development in the goat epididymis. To assess the expression patterns of TJ proteins in immature (3 months of age) and mature (14 months of age) goat epididymides, two different experimental methods were used including immunofluorescence labeling and western blotting. We show that, ZO-1, 2, and 3, and occludin, were strictly expressed and localized to the TJs of the goat epididymis, whereas Cldn3 was present in basolateral membranes as well as TJs. All TJ proteins examined were more highly expressed in the immature epididymis compared to levels in mature tissue. In conclusion, our study indicates that at least five TJ proteins, namely ZO-1, ZO-2, ZO-3, occludin, and Cldn3, are present in TJs, and the expression strength and pattern of TJ proteins tend to be age dependent in the goat epididymis. Together, these data suggest that the distinct expression patterns of TJ proteins are essential for regulating components of the luminal contents in the epididymal epithelium and for forming adequate luminal conditions that are necessary for the maturation, protection, transport, and storage of spermatozoa in the goat epididymis.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.21-21
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• 2001

PDZ domains are molecular-recognition elements that mediate protein-protein interactions. The PDZ domain was discovered originally as a common motif present in three structurally related proteins： PSD-95 (postsynaptic density protein), Dlg (discs-large protein) and ZQ-1 (zonula occludens-1). The PDZ domain is globular domain, containing about 80-100 amino acids, and a conserved motif with two alpha helices and six beta strands. Most of them bind selectively to the C-termini of the interacting proteins at the complexes of signaling molecules and membrane associated receptors.(omitted)

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1480-1487
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• 2020

Our previous report determined that miR-144 is a key regulator of intestinal epithelial permeability in irritable bowel syndrome with diarrhea (IBS-D) rats. Recent evidence has shown that lactobacilli play an important role in the relief of IBS-D symptoms. However, few studies have addressed the mechanisms by which microRNAs and lactobacilli exert their beneficial effects on intestinal epithelial permeability. Hence, to elucidate whether miRNAs and lactobacilli play roles in intestinal epithelial barrier regulation, we compared miRNA expression levels in intestinal epithelial cells (IECs) under Lactobacillus casei (L. casei LC01) treatment. IECs and L. casei LC01 were co-cultured and then subjected to microRNA microarray assay. qRT-PCR, western blot and ELISA were used to detect the expression of occludin (OCLN) and zonula occludens 1 (ZO1/TJP1). The interaction between miRNAs and L. casei LC01 acting in IECs was investigated through transfection of RNA oligoribonucleotides and pcDNA 3.1 plasmid. The results are as follows: 1) L. casei LC01 decreased the expression of miR-144 and FD4 and promoted OCLN and ZO1 expression in IECs; 2) L. casei LC01 enhanced the barrier function of IECs via downregulation of miR-144 and upregulation of OCLN and ZO1; 3) Under L. casei LC01 treatment, OCLN and ZO1 overexpression could partially eliminate the promoting effect of miR-144 on intestinal permeability in IECs. Our results demonstrate that L. casei LC01 regulates intestinal permeability of IECs through miR-144 targeting of OCLN and ZO1. L. casei LC01 can be a possible therapeutic target for managing dysfunction of the intestinal epithelial barrier.

• Journal of Life Science
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• v.25 no.1
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• pp.101-112
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• 2015

A type of cell junction that is formed between different parts within the same cell is called autotypic cell junction. Autotypic junction proteins form tight junctions found between membrane lamellae of a cell, especially in myelinating glial cells. Some of them have postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domains, which interact with the carboxyl (C)-terminal PDZ-binding motif of other proteins. PDZ domains are protein-protein interaction modules that play a role in protein complex assembly. The PDZ domain, which is widespread in bacteria, plants, yeast, metazoans, and Drosophila, allows the assembly of large multi-protein complexes. The multi-protein complexes act in intracellular signal transduction, protein targeting, and membrane polarization. The identified PDZ domain-containing proteins located at autotypic junctions include zonula occludens-1 (ZO-1), ZO-2, pals-1-associated tight junction protein (PATJ), multi-PDZ domain proteins (MUPPs), membrane-associated guanylate kinase inverted 2 (MAGI2), and protease-activated receptor (PAR)-3. PAR-3 interacts with atypical protein kinase C and PAR-6, forming a ternary complex, which plays an important role in the regulation of cell polarity. MAGI2 interacts with ${\alpha}$-amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA) receptor at excitatory synapses. PATJ is detected in paranodal loops associated with claudin-1. On the other hand, MUPP1 is found in mesaxons and Schmidt-Lanterman incisures with claudin-5. ZO-1, ZO-2, and PAR-3 are found at all three sites. Different distributions of PDZ domain-containing proteins affect the development of autotypic junctions. In this review, we will describe PDZ domain-containing proteins at autotypic tight junctions in myelinating Schwann cells and their roles.

• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.87-101
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• 1997

The development of trachea in fetuses on 60, 90 and 120 days of gestation and neonates of Korean native goats was investigated by microscopy and scanning and transmission electron microscopy. The results were summarized as follows; Light microscopic studies: 1. In the 60-day-old fetuses, the tracheal walls were differentiated and divided into four layers of the mucosa, submucosa, muscle and cartilage, and adventitia. The tracheal epithelium is composed of stratified ciliated columnar epithelium at 60- and 90-day-old fetuses while the epithelium observed at 120-day-old fetuses was pseudostraified ciliated colummar epithelium. 2. In the 90-day-old fetuses, tracheal glands extended into the submucosa and peripheral area of the tracheal cartilage. The blood vessels were observed in the submucosa and adventitia. The elastic and collagenous fibers were observed in the tracheal walls. 3. In the neonates, the tracheal walls consisted of mucosa with well-developed folds, submucosa, tracheal glands, muscle and cartilage, collagenous and elastic fibers, and adventitia, which were more developed than those of 120-day-old fetuses. The tracheal epithelium was developed as that in adults. Scanning electron microscopic studies: 4. In the 60-day-old fetuses, most of tracheal epithelial cells were nonciliated but short microvilli were sporadically observed on the luminal surface. On rare occasions, a few cells have solitary cilium. 5. In the 90-day-old fetuses, the ciliated cells appeared increasingly and cilia elongated longer than those of 60-day-old fetuses. 6. In the 120-day-old fetuses, the nonciliated cells covered with microvilli in dome-shape were barriered by thick carpet of cilia. The nonciliated cells also have many papillary projectons on the apical surface. 7. In the neonates, the nonciliated cells in tracheal epithelium were covered compactly with numerous cilia, and many secretory droplets were found on the cilia. Transmission electron microscopic studies: 8. In the 60-day-old fetuses, nonciliated cells of the tracheal epithelium contain large amounts of glycogen granules in the supernuclear and subnuclear areas meanwhile a few cell organelles were formed. Cilia were well formed along the apical cell membranes of the ciliated cells. Also found in the ciliated cells were basal corpuscles, mitochondria and short chains in granular endoplasmic reticulum(GER). Between the epithelial cells presented were well-defined junctional complex with zonula occludens and desmosomes. The nuclei were variable in size and shape. The more developed nucleoli were observed conspicuosly. 9. In the 90-day-old fetuses, nonciliated cells contained large glycogen granules. Accumulated glycogen granules were observed in the subnuclear and supranuclear portion of the cytoplasm. A few short microvilli were covered with glycocalyx. Ciliated cells contained numerous mitochondria and short chains of GER. 10. In the 120-day-old fetuses, the ciliated cells contained numerous mitochondria, abundant short chains of GER and nucleoli. Nonciliated cells contained some Golgi complex and mitochondria. The cell borders were well-defined and distinct junctional complex with zonula occludens, desmosomes, and interdigitorum. 11. In the neonates, well-developed goblet cells were observed in the tracheal epithelium. Ultrastructures of ciliated and nonciliated cells on the tracheal epithelia were similar in pattern as those in adults.

• Journal of Ginseng Research
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• v.37 no.1
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• pp.94-99
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• 2013

Proteinuric conditions demonstrate structural and compositional changes of the foot processes and slit diaphragms between podocytes. p130Cas in podocytes serves as an adapter protein anchoring glomerular basement membrane to actin filaments of podocyte cytoskeleton. To investigate the effect of ginseng total saponin (GTS) on the pathologic changes of podocyte p130Cas induced by diabetic conditions, we cultured mouse podocytes under: 1) normal glucose (5 mM, control); 2) high glucose (HG, 30 mM); 3) advanced glycosylation endproducts (AGE)-added; or 4) HG plus AGE-added conditions and treated with GTS. In confocal imaging, p130Cas colocalized with zonula occludens-1 and synaptopodin connecting to F-actin. However, diabetic conditions relocalized p130Cas molecules at perinuclear cytoplasmic area and reduced the intensity of p130Cas. In Western blotting, diabetic conditions, especially HG plus AGE-added condition, decreased cellular p130Cas protein levels at 24 and 48 h. GTS improved such quantitative and qualitative changes. These findings imply that HG and AGE have an influence on the redistribution and amount of p130Cas of podocytes, which can be reversed by GTS.

• Journal of Life Science
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• v.24 no.12
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• pp.1276-1283
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• 2014

Cell adhesion molecules determine the cell-cell binding and the interactions between cells and extracellular signals. Cell-cell junctional complexes, which maintain the structural integrity of tissues, consist of more than 50 proteins including multi-PDZ domain protein 1 (MUPP1). MUPP1 contains 13 postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domains and serves a scaffolding function for transmembrane proteins and cytoskeletal proteins or signaling proteins, but the mechanism how MUPP1 links and stabilizes the juxtamembrane proteins has not yet been elucidated. We used the yeast two-hybrid system to identify proteins that interact with PDZ domains of MUPP1. We found an interaction between MUPP1 and cell adhesion molecule 1 (Cadm1, also known as SynCAM1, Necl-2, or TSLC1). Cadm1 bound to the second PDZ domain of MUPP1. The carboxyl (C)-terminal end of Cadm1 has a type II PDZ-association motif (-Y-F-I) which was essential for the interaction with MUPP1 in the yeast two-hybrid assay. MUPP1 also bound to the C-terminal cytoplasmic tail region of other Cadm family members (Cadm2, Cadm3, and Cadm4). In addition, these protein-protein interactions were observed in the glutathione S-transferase (GST) pull-down assay and by co-immunoprecipitation. Anti-MUPP1 antibody co-immunoprecipitated Cadm1 and Cadm4 with MUPP1 from mouse brain extracts. These results suggest that MUPP1 could mediate interaction between Cadms and cytoskeletal proteins.

• Journal of Veterinary Science
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• v.24 no.3
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• pp.23.1-23.16
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• 2023

Background: Irritable bowel syndrome (IBS) is a functional bowel disorder (FBD). Objectives: To assess the therapeutic effects of paeoniflorin (PF) on IBS in rats. Method: Sixty male Sprague-Dawley rats were randomly divided into normal, model, positive drug, low-dose PF, medium-dose PF and high-dose PF groups (n = 10). After gavage for 2 consecutive weeks, the effect of PF on abdominal pain symptoms was assessed based on the abdominal withdrawal reflex (AWR) score, fecal water content and pathological changes in colon tissues. D-lactate, interleukin-1β (IL-1β), transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay, and phosphorylated nuclear factor kappa B (p-NF-κB) p65 was detected by Western blotting. The abundance and diversity changes of intestinal flora were explored using 16S ribosomal RNA sequencing. Result: In PF groups, the mucosal morphology of colon tissues was intact, and the glands were arranged neatly and structured clearly, without obvious inflammatory cell infiltration. Compared with the model group, PF groups had significantly elevated pain threshold, and mRNA and protein levels of zonula occludens-1 (ZO-1) and occludin, decreased AWR score at 20 mmHg pressure, fecal water content, mRNA levels of IL-1β, TGF-β, and TNF-α, protein level of p-NF-κB p65 and level of serum D-lactate, and reduced levels of serum IL-1β, TGF-β, and TNF-α (p < 0.05, p < 0.01). PF groups had higher abundance of Lactobacillus, Akkermansia, Alistipes, and Bacteroides, but lower abundance of Desulfovibrio, Parasutterella, and Enterococcus than those of the model group. Conclusions: PF exerts therapeutic effects on IBS in rats probably by regulating the intestinal flora, and then up-regulating the expressions of ZO-1 and occludin in colon tissue while down-regulating the levels of IL-1β, TGF-β, TNF-α, D-lactate and p-NF-κB p65.