OBJECTIVETo observe the effect of SIRT1 on intestinal barrier function of epithelial Caco-2 cells under hypoxia and investigate its mechanism.

METHODSCaco-2 cells were randomly divided into three groups: normoxia group (Nx), hypoxia group (Hx,1%O2 for 6 h) and hypoxia plus 40 μmol/L Resveratrol (agonist of SIRT1) group (Hx+Res). Transepithelial electrical resistance (TER) was determined. mRNA and protein expressions of SIRT1 and tight junctions (ZO-1, Occludin, Claudin-1) were examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting.

RESULTSBoth mRNA and protein expressions of SIRT1 were significantly reduced in Hx group as compared with Nx group (0.40±0.02 vs. 0.70±0.07, P=0.001; 0.37±0.03 vs. 0.76±0.03, P=0.001). The mRNA and protein expressions of SIRT1 were significantly increased in Hx+Res group as compared with Hx group(0.50±0.02 vs. 0.40±0.02, P=0.026; 0.54±0.02 vs. 0.37±0.03, P=0.011). The expression levels of ZO-1, Occludin and Claudin-1 in Hx group were lower than those in Nx group (P<0.05), however, pretreatment with Resveratrol could attenuate the decreased expression of above 3 molecules under hypoxia(P<0.05). TERs of Nx group, Hx group and Hx+Res group were (142±7) Ohm/cm(2), (94±3) Ohm/cm(2) and (119±7) Ohm/cm(2) respectively. Compare with the Nx group, the TER of Hx group was significantly decreased(P<0.05). TER of Hx+Res group was significantly increased compare with Hx group, but it was still significantly lower than that in Nx group(P<0.05).

CONCLUSIONSExpression of SIRT1 is significantly reduced under hypoxia. Activation of SIRT1 can maintain the epithelial barrier function through regulating the expression of tight junctions under hypoxia.

Caco-2 Cells ; Cell Hypoxia ; Claudin-1 ; metabolism ; Epithelial Cells ; metabolism ; Humans ; Intestinal Mucosa ; cytology ; Occludin ; metabolism ; Sirtuin 1 ; metabolism ; Zonula Occludens-1 Protein ; metabolism

After a series of studies, we found that the intestinal permeability was increased, tight junction protein (zonula occluden-1) obviously decreased and redistributed, accompanied by an increase in expression of myosin light chain (MLC) phosphorylation in severely burned rats. After using inhibitor of MLC kinase (ML-9 2 mg/kg) or of Rho-associated kinase (Y-27632 2 mg/kg), above-mentioned changes could be alleviated. Therefore, to regulate the MLC phosphorylation of tight junction protein and perijunctional actin-myosin ring may be one of the key links to lessen the intestinal epithelium permeability after burn injury.
Animals ; Burns ; metabolism ; Intestinal Mucosa ; metabolism ; Intestines ; metabolism ; Membrane Proteins ; metabolism ; Myosin Light Chains ; metabolism ; Permeability ; Phosphoproteins ; metabolism ; Phosphorylation ; Rats ; Zonula Occludens-1 Protein ; rho-Associated Kinases ; metabolism

OBJECTIVETo observe the effect of 25-hydroxyvitamin D3 on the permeability and ZO-1 expression in normal human airway epithelial cells.

METHODSMTT assay was used to assess the viability of human airway epithelial cell line 16HBE following a 24-hour exposure to different concentrations of 25-hydroxy vitamin D3, and the transepithelial electrical resistance (TER) of the cell monolayer was measured using a Millicell-ERS voltohmmeter. Real-time quantitative RT-PCR was employed to determine the changes of ZO-1 mRNA expression in the cells following the exposures.

RESULTSExposure to 25-hydroxyvitamin D3 resulted in significantly increased permeability of 16HBE cells, but the exspression of ZO-1 showed no obvious changes. 25-hydroxyvitamin D3 at 4×10(-9) mol/L showed the strongest effect in increasing the permeability of cell monolayer.

CONCLUSION25-hydroxyvitamin D3 increases the permeability of normal bronchial airway epithelial cell monolayer in vitro, but this effect is not mediated by upregulation of ZO-1 expression.

Bronchi ; cytology ; metabolism ; Calcifediol ; pharmacokinetics ; pharmacology ; Cell Line ; Cell Membrane Permeability ; drug effects ; Epithelial Cells ; cytology ; metabolism ; Humans ; RNA, Messenger ; genetics ; metabolism ; Zonula Occludens-1 Protein ; genetics ; metabolism

OBJECTIVE: To observe the time-course expression of zonula occludens-1 (ZO-1) in cerebral cortex after traumatic brain injury (TBI). METHODS: The TBI model of mouse was established. The mice were divided in 1 h, 3 h, 6 h, 12 h, 24 h, 3 d, 7 d after TBI, sham and control groups. The permeability of the blood brain barrier was evaluated by measuring the extravasation of Evans blue (EB) dye. The expression of ZO-1 in cerebral cortex in the injured area was detected by Western blotting and immunohistochemistry. RESULTS: The extravasation of EB dye of injured cortex gradually increased from 1 h, peaked at 1-3 d and approximately decreased to normal at 7 d after TBI. Western blotting revealed that the expression of ZO-1 gradually decreased after 1 h, was at the lowest at 1-3 d, and then significantly increased after 7 d but was still lower than that of normal and sham groups. The result of immunohistochemistry showed that ZO-1 had strong expression in vessel of normal cortex, gradually decreased after TBI, and almost disappeared at 3 d after TBI and gradually recovered to normal level later. CONCLUSION The expression of ZO-1 in the injured cortex after TBI initially decreases and then increases. The negative correlation between ZO-1 expression and EB extravasation after TBI could be used as a new indicator for wound age estimation.
Animals ; Blood-Brain Barrier ; Blotting, Western ; Brain Injuries/physiopathology* ; Cerebral Cortex/metabolism* ; Immunohistochemistry ; Mice ; Permeability ; Tight Junctions/metabolism* ; Zonula Occludens-1 Protein/metabolism*

This paper is aimed to investigate the effect of fluid shear stress on the tight junction of laryngeal squamous carcinoma (Hep2) cells and to explore the potential molecular mechanism. Hep2 cells were selected and subjected to the fluid shear stress of 1.4 dyn/cm2 for different time, respectively. The morphological changes of Hep2 cells under shear stress were observed using inverted microscope. The cell-cell junctions were examined by transmission electron microscope (TEM). The expressions of tight junction proteins (including Occludin, Claudin-5 and ZO-1) and the distribution of Claudin-5 were examined by Western blot assay and laser scanning confocal microscope, respectively. The results indicated that Hep2 cells turned to spindle-like shapes after exposed to shear stress, and showed the trend of the recovering to original shapes when the shear stress was cancelled. The cell-cell junctions were tight under the shear flow condition, and the permeability was reduced under the condition of 1.4 dyn/cm shear flow. The expressions of tight junction proteins were enhanced with increased duration of shear flow, but reduced after removing shear flow. The result of Claudin-5 expression by immufluorescence assay was consistent with that by Western blot. The Claudin-5 mainly distributed in the cytoplasm under static condition, while it located at the intercellular after shear flow stimulation, and it appeared intercellular and cytoplasm after stopping shear flow stimulation. Therefore, it can be concluded that shear stress changes the morphology of laryngeal squamous carcinoma Hep2 cells, and upregulates the tight junction.
Blotting, Western ; Carcinoma, Squamous Cell ; pathology ; Claudin-5 ; metabolism ; Hep G2 Cells ; Humans ; Laryngeal Neoplasms ; pathology ; Occludin ; metabolism ; Stress, Mechanical ; Tight Junctions ; Zonula Occludens-1 Protein ; metabolism

OBJECTIVEThe purpose of this study was to assess weather the immortalized mouse brain endothelial cell line Bend.3 displays the comparative barrier characteristics as the primary brain microvascular endothelial cells (BEMC).

METHODSImmortalized mouse brain endothelial cell line, Bend.3 cells were cultured in transwell inserts and their restrictive characteristics were assessed by transendothelial electrical resistance (TEER) and horseradish peroxidase (HRP) permeability assays. Western blot and direct fluorescent staining methods were used to detect the tight junction protein expression and F-actin distribution.

RESULTSThe TEER in Bend.3 cells increased with the prolonged culture time and increased to 82.3+/-6.0 Omega cm2 10 days after culture, which was significantly higher than that 3 days after culture (37.3+/-3.1 Omega cm2; P<0.05). There were significant differences in the permeability rates for HRP 3 and 10 days after culture (4.3+/-0.20)% vs (2.2+/-0.05)% (P<0.05). Western blot indicated high level expression of tight junction proteins occludin and ZO-1 in Bend.3 cells 10 days after culture. F-actin was visualized around the cell membrane and presented scrobiculate linear fluorescence 10 days after culture.

CONCLUSIONSBend.3 cells have similar barrier characteristics to BEMC, and their barrier function may reach to the best effect 10 days after culture.

Actins ; analysis ; Animals ; Blood-Brain Barrier ; Cell Line ; Electric Impedance ; Endothelial Cells ; metabolism ; Horseradish Peroxidase ; metabolism ; Membrane Proteins ; analysis ; Mice ; Phosphoproteins ; analysis ; Zonula Occludens-1 Protein

The study was aimed to identify a new leukemia related gene zo-1 from leukemia and to explore its mechanism in leukemia. Methylation specific PCR (MSP) was used for testing gene zo-1 methylation in leukemia cells. The gene zo-1 specific siRNA was designed according to its sequence, and transfected into THP-1 cell, and the cells were cultured for 48 hours before harvesting. The effect of zo-1 siRNA was monitored by RT-PCR. The cellular proliferation activity was assayed by CCK-8, the apoptosis was detected by Annexin-V-fluorescence in isothiocyanate (FITC) assay, and cell cycle was observed by propidium iodide (PI). The results indicated that the gene zo-1 in patients with acute leukemia was hypermethylated, while the gene zo-1 in healthy persons was unmethylated. The THP-1 cells with unmethylation of zo-1 gene promoter overexpressed the gene zo-1, while the Molt4 and HL-60 cells with hypermethylation of gene zo-1 promoter did not express the gene zo-1. The silenced zo-1 gene in Molt4 and HL-60 leukemia cell lines could be reactivated by demethylation treatment with 5-AZA-dC. The oligofectamine-transfected siRNA for zo-1 gene successfully inhibited the expression of gene zo-1 in THP-1 cells, but did not interfere with cell proliferation, cell cycle and apoptosis. It is concluded that gene zo-1 is a leukemia-related gene. Gene zo-1 in acute leukemia was hypermethylated, the methylation status of gene zo-1 regulates the expression of gene zo-1. Lack of gene zo-1 expression in THP-1 cells does not influence the cell proliferation, apoptosis and cell cycle, which suggests that the methylation of gene zo-1 may be involved in the genesis of acute leukemia, its mechanism is worthy to be studied.
CpG Islands ; DNA Methylation ; Gene Silencing ; HL-60 Cells ; Humans ; Leukemia ; genetics ; Membrane Proteins ; metabolism ; Phosphoproteins ; metabolism ; RNA, Small Interfering ; genetics ; Zonula Occludens-1 Protein

OBJECTIVETo explore ZO-1 gene expression and methylation in leukemia cells and the involvement of ZO-1 gene in leukemogenesis.

METHODSRestriction landmark genomic scanning (RLGS) was used to identify new leukemia related gene, and methylation specific PCR (MSP) for ZO-1 methylation status. ZO-1 specific siRNA was designed and prepared by in vitro transcription and transfected into K562 cells, the transfected cells were cultured for 48 hours before harvesting. The effect of ZO-1 siRNA was monitored by Northern blot. Cellular proliferation capacity was assayed by CCK-8, cell apoptosis by Annexin V-fluorescence in isothiocyanate (FITC) assay, and cell cycle by phosphatidylinositol (PI).

RESULTSThe intensified spots in RLGS gel were subjected to bioinformatics analysis and one of the candidate spots was proved to be ZO-1 gene. In fresh leukemia cells, Molt4 cells and HL-60 cells, ZO-1 was hypermethylated, causing it reduced or silenced. ZO-1 gene was highly expressed with no methylation in normal peripheral blood MNC and K562 cells. There was a good correlation between promoter methylation and the gene silence. The silenced gene can be re-activated by demethylation treatment with 5-AZA-dC in most leukemia cell lines. RNA interference for ZO-1 gene in K562 cells did not interfere with cell proliferation, cell cycle and apoptosis.

CONCLUSIONZO-1 gene methylation might be involved in the tumorigenesis of acute leukemia.

Animals ; DNA Methylation ; HL-60 Cells ; Humans ; K562 Cells ; Leukemia ; genetics ; pathology ; Membrane Proteins ; genetics ; metabolism ; Mice ; Phosphoproteins ; genetics ; metabolism ; Zonula Occludens-1 Protein

OBJECTIVETo explore the effects of acrylamide on the permeability of blood cerebrospinal fluid barrier (BCB) and tight junction protein ZO-1 of choroid plexus in rats and to provide a theoretical basis for explaining the mechanism of nerve injury induced by acrylamide.

METHODSThirty two male Sprague-Dawley rats were randomly divided into ACR and control groups. ACR group was exposed to 20 mg/kg ACR daily for 5 days a week by intraperitoneal injection (i.p.) for 4 weeks. Control group was exposed to normal saline. The neurobehavioral tests (including sensatory and motor functions) were performed every week. At the end of exposure, Evan blue (EB) and Sodium fluorescein (NaFI) content in rat CSF were detected for determining the BCB permeability, Real-time PCR was used to measure the expression levels of ZO-1 mRNA in the epithelium cells of choroid plexus, and laser scanning confocal microscope (LSCM) was utilized to observe the distribution of ZO-1 protein.

RESULTSNeurobehavioral tests showed that the tail-flick latencies of ACR group were 27.77% and 53.71% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). The hind lamb splay distances of ACR group were 131.76% and 153.77% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). Evan blue (EB) and Sodium fluorescein (NaFI) content of ACR group were significantly higher than those of control group (P < 0.05). In the 4th week, the expression level of ZO-1 mRNA in ACR group was 0.21 +/- 0.07, which was significantly lower than that (0.31 +/- 0.11) in control group (P < 0.05). In the 4th week, the ZO-1 protein expression level of choroid plexus in ACR group was significantly lower than that in control group (P < 0.05).

CONCLUSIONAcrylamide could increased the BCB permeability of rats, which may be involved in the central nervous injury induced by ACR.

Acrylamide ; toxicity ; Animals ; Blood-Brain Barrier ; drug effects ; Choroid Plexus ; metabolism ; Male ; Permeability ; drug effects ; Rats ; Rats, Sprague-Dawley ; Zonula Occludens-1 Protein ; metabolism

Recently, several studies showed that gastrointestinal tract may be associated with pathophysiology of Parkinson's disease (PD). Intestine tight junction protein zonula occluden-1 (ZO-1) is an important component of intestinal barrier which can be degraded by matrix metallopeptidase 9 (MMP-9). In our previous study, a significant decline in ZO-1 was observed along with enhanced MMP-9 activity in the duodenum and distal colon of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice. In this study, the protective effect of simvastatin on ZO-1 was investigated using an MPTP mouse model of PD. Seven days after the end of MPTP application, the expression level of ZO-1 was evaluated by immunohistochemistry. The protein expression levels of ZO-1 and MMP9 were detected by Western blotting. Meanwhile, MMP-9 activity was analyzed by gelatin zymography. MPTP treatment led to a decrease in the expression of ZO-1, which was accompanied by elevated MMP-9 activity. Treatment with simvastatin could partly reverse the MPTP-induced changes in ZO-1 expression and reduce MMP-9 protein and activity. Taken together, these findings suggest that simvastatin administration may partially reverse the impairment of ZO-1 induced by MPTP via inhibiting the activity of MMP9, fortify the impaired intestinal barrier and limit gut-derived toxins that pass across the intestinal barrier.
Animals ; Disease Models, Animal ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; pharmacology ; Mice ; Parkinson Disease ; metabolism ; Simvastatin ; pharmacology ; Zonula Occludens-1 Protein ; drug effects