共查询到20条相似文献,搜索用时 15 毫秒
1.
Prashant K. Nighot Chien-An Andy Hu Thomas Y. Ma 《The Journal of biological chemistry》2015,290(11):7234-7246
Autophagy is an intracellular degradation pathway and is considered to be an essential cell survival mechanism. Defects in autophagy are implicated in many pathological processes, including inflammatory bowel disease. Among the innate defense mechanisms of intestinal mucosa, a defective tight junction (TJ) barrier has been postulated as a key pathogenic factor in the causation and progression of inflammatory bowel disease by allowing increased antigenic permeation. The cross-talk between autophagy and the TJ barrier has not yet been described. In this study, we present the novel finding that autophagy enhances TJ barrier function in Caco-2 intestinal epithelial cells. Nutrient starvation-induced autophagy significantly increased transepithelial electrical resistance and reduced the ratio of sodium/chloride paracellular permeability. Nutrient starvation reduced the paracellular permeability of small-sized urea but not larger molecules. The role of autophagy in the modulation of paracellular permeability was confirmed by pharmacological induction as well as pharmacological and genetic inhibition of autophagy. Consistent with the autophagy-induced reduction in paracellular permeability, a marked decrease in the level of the cation-selective, pore-forming TJ protein claudin-2 was observed after cell starvation. Starvation reduced the membrane presence of claudin-2 and increased its cytoplasmic, lysosomal localization. Therefore, our data show that autophagy selectively reduces epithelial TJ permeability of ions and small molecules by lysosomal degradation of the TJ protein claudin-2. 相似文献
2.
Michael S. Dicay Christina L. Hirota Natalie J. Ronaghan Michael A. Peplowski Raza S. Zaheer Colin A. Carati Wallace K. MacNaughton 《PloS one》2015,10(3)
Inflammatory bowel diseases are associated with dysregulated electrolyte and
water transport and resultant diarrhea. Aquaporins are transmembrane proteins
that function as water channels in intestinal epithelial cells. We investigated
the effect of the inflammatory cytokine, interferon-γ, which is a major
player in inflammatory bowel diseases, on aquaporin-1 expression in a mouse
colonic epithelial cell line, CMT93. CMT93 monolayers were exposed to 10 ng/mL
interferon-γ and aquaporin-1 mRNA and protein expressions were measured
by real-time PCR and western blot, respectively. In other experiments, CMT93
cells were pretreated with inhibitors or were transfected with siRNA to block
the effects of Janus kinases, STATs 1 and 3, or interferon regulatory factor 2,
prior to treatment with interferon-γ. Interferon-γ decreased
aquaporin-1 expression in mouse intestinal epithelial cells in a manner that did
not depend on the classical STAT1/JAK2/IRF-1 pathway, but rather, on an
alternate Janus kinase (likely JAK1) as well as on STAT3. The pro-inflammatory
cytokine, interferon-γ may contribute to diarrhea associated with
intestinal inflammation in part through regulation of the epithelial aquaporin-1
water channel via a non-classical JAK/STAT receptor signalling pathway. 相似文献
3.
Kashiwamura Y Sano Y Abe M Shimizu F Haruki H Maeda T Kawai M Kanda T 《Neurochemical research》2011,36(5):849-855
In autoimmune disorders of the peripheral nervous system (PNS), including Guillain–Barré syndrome and chronic inflammatory
demyelinating polyradiculoneuropathy, breakdown of the blood-nerve barrier (BNB) has been considered to be a key step in the
disease process. Although glucocorticoids (GCs) have been shown to effectively restore the blood–brain barrier (BBB) in some
inflammatory central nervous system diseases such as multiple sclerosis, their action against the BNB has not yet been examined.
To elucidate the role of GCs on the BNB, we established a novel human immortalized endothelial cell lines derived from the
BNB. The established cell line termed “DH-BNBs” expresses two important tight junction proteins, claudin-5 and occludin. Using
DH-BNBs, we analyzed how GCs affect BNB function. We herein report that GCs up-regulate the expression of claudin-5 and increase
the barrier properties of the BNB. This is the first report which indicates how GCs affect the blood-nerve barrier. 相似文献
4.
Huachen Gan Guibo Wang Qin Hao Q. Jane Wang Hua Tang 《The Journal of biological chemistry》2013,288(52):37343-37354
At the interface between host and external environment, the airway epithelium serves as a major protective barrier. In the present study we show that protein kinase D (PKD) plays an important role in the formation and integrity of the airway epithelial barrier. Either inhibition of PKD activity or silencing of PKD increased transepithelial electrical resistance (TEER), resulting in a tighter epithelial barrier. Among the three PKD isoforms, PKD3 knockdown was the most efficient one to increase TEER in polarized airway epithelial monolayers. In contrast, overexpression of PKD3 wild type, but not PKD3 kinase-inactive mutant, disrupted the formation of apical intercellular junctions and their reassembly, impaired the development of TEER, and increased paracellular permeability to sodium fluorescein in airway epithelial monolayers. We further found that overexpression of PKD, in particular PKD3, markedly suppressed the mRNA and protein levels of claudin-1 but had only minor effects on the expression of other tight junctional proteins (claudin-3, claudin-4, claudin-5, occludin, and ZO-1) and adherent junctional proteins (E-cadherin and β-catenin). Immunofluorescence study revealed that claudin-1 level was markedly reduced and almost disappeared from intercellular contacts in PKD3-overexpressed epithelial monolayers and that claudin-4 was also restricted from intercellular contacts and tended to accumulate in the cell cytosolic compartments. Last, we found that claudin-1 knockdown prevented TEER elevation by PKD inhibition or silencing in airway epithelial monolayers. These novel findings indicate that PKD negatively regulates human airway epithelial barrier formation and integrity through down-regulation of claudin-1, which is a key component of tight junctions. 相似文献
5.
Xiaoyu Liu Gui Yang Xiao-Rui Geng Yanjuan Cao Na Li Li Ma Si Chen Ping-Chang Yang Zhigang Liu 《PloS one》2013,8(8)
The epithelial barrier dysfunction is an important pathogenic feature in a number of diseases. The underlying mechanism is to be further investigated. The present study aims to investigate the role of tight junction protein claudin-2 (Cldn2) in the compromising epithelial barrier function. In this study, the expression of Cldn2 in the epithelial layer of mice and patients with food allergy was observed by immunohistochemistry. The induction of Cldn2 was carried out with a cell culture model. The Cldn2-facilitated antigen internalization was observed by confocal microscopy. The epithelial barrier function in the gut epithelial monolayer was assessed by recording the transepithelial resistance and assessing the permeability to a macromolecular tracer. The results showed that the positive immune staining of Cldn2 was observed in the epithelial layer of the small intestine that was weakly stained in naïve control mice, and strongly stained in sensitized mice as well as patients with food allergy. Exposure to cholera toxin or Staphylococcal enterotoxin B induced the expression of Cldn2 in HT-29 or T84 cells. Cldn2 could bind protein antigen to form complexes to facilitate the antigen transport across the epithelial barrier. Blocking Cldn2 prevented the allergen-related hypersensitivity the intestine. We conclude that the tight junction protein Cldn2 is involved in the epithelial barrier dysfunction. 相似文献
6.
Claudins are transmembrane proteins of the tight junction that determine and regulate paracellular ion permeability. We previously
reported that claudin-8 reduces paracellular cation permeability when expressed in low-resistance Madin-Darby canine kidney
(MDCK) II cells. Here, we address how the interaction of heterologously expressed claudin-8 with endogenous claudin isoforms
impacts epithelial barrier properties. In MDCK II cells, barrier improvement by claudin-8 is accompanied by a reduction of
endogenous claudin-2 protein at the tight junction. Here, we show that this is not because of relocalization of claudin-2
into the cytosolic pool but primarily due to a decrease in gene expression. Claudin-8 also affects the trafficking of claudin-2,
which was displaced specifically from the junctions at which claudin-8 was inserted. To test whether replacement of cation-permeable
claudin-2 mediates the effect of claudin-8 on the electrophysiological phenotype of the host cell line, we expressed claudin-8
in high-resistance MDCK I cells, which lack endogenous claudin-2. Unlike in MDCK II cells, induction of claudin-8 in MDCK
I cells (which did not affect levels of endogenous claudins) did not alter paracellular ion permeability. Furthermore, when
endogenous claudin-2 in MDCK II cells was downregulated by epidermal growth factor to create a cell model with low transepithelial
resistance and low levels of claudin-2, the permeability effects of claudin-8 were also abolished. Our findings demonstrate
that claudin overexpression studies measure the combined effect of alterations in both endogenous and exogenous claudins,
thus explaining the dependence of the phenotype on the host cell line. 相似文献
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8.
Yosuke Shimada Makoto Kinoshita Kazuo Harada Masafumi Mizutani Kazunori Masahata Hisako Kayama Kiyoshi Takeda 《PloS one》2013,8(11)
Microbiota have been shown to have a great influence on functions of intestinal epithelial cells (ECs). The role of indole as a quorum-sensing (QS) molecule mediating intercellular signals in bacteria has been well appreciated. However, it remains unknown whether indole has beneficial effects on maintaining intestinal barriers in vivo. In this study, we analyzed the effect of indole on ECs using a germ free (GF) mouse model. GF mice showed decreased expression of junctional complex molecules in colonic ECs. The feces of specific pathogen-free (SPF) mice contained a high amount of indole; however the amount was significantly decreased in the feces of GF mice by 27-fold. Oral administration of indole-containing capsules resulted in increased expression of both tight junction (TJ)- and adherens junction (AJ)-associated molecules in colonic ECs in GF mice. In accordance with the increased expression of these junctional complex molecules, GF mice given indole-containing capsules showed higher resistance to dextran sodium sulfate (DSS)-induced colitis. A similar protective effect of indole on DSS-induced epithelial damage was also observed in mice bred in SPF conditions. These findings highlight the beneficial role of indole in establishing an epithelial barrier in vivo. 相似文献
9.
哺乳动物肠上皮是一种拥有快速自我更新能力的组织,在维持机体免疫稳态与肠道应激后的损伤修复中发挥重要作用。源于隐窝底部的多能肠干细胞不断进行增殖、迁移与分化,并沿隐窝 绒毛轴向上移动,从而维持肠上皮完整性。该过程受严格而复杂的基因调控网络参与。越来越多的数据表明,肠上皮完整性受到广泛的非编码RNA的调控,主要包括肠黏膜再生、保护与上皮屏障功能等方面。本文重点讨论了两类非编码RNA(包括microRNAs和lncRNAs)转录后调控肠上皮屏障功能的研究进展。其中,miR-503、miR-146和lnc-uc.173、lnc-SPRY4-IT1、lnc-plncRNA1、lnc-Gata6等,能够促进肠黏膜的更新,增强上皮屏障功能;相反,miR-222、miR-29b、miR-195和lnc-H19与lnc-BC012900等,抑制肠上皮再生并破坏肠上皮屏障功能。miRNAs、mRNAs与lncRNAs间构成复杂的分子网络,共同调控肠上皮稳态。深入研究与肠上皮相关的miRNAs和IncRNAs分子及其作用机制,探寻引起肠黏膜炎症的关键分子靶标,为肠道炎症临床诊治提供新方向与新方法。 相似文献
10.
哺乳动物肠上皮是一种拥有快速自我更新能力的组织,在维持机体免疫稳态与肠道应激后的损伤修复中发挥重要作用。源于隐窝底部的多能肠干细胞不断进行增殖、迁移与分化,并沿隐窝 绒毛轴向上移动,从而维持肠上皮完整性。该过程受严格而复杂的基因调控网络参与。越来越多的数据表明,肠上皮完整性受到广泛的非编码RNA的调控,主要包括肠黏膜再生、保护与上皮屏障功能等方面。本文重点讨论了两类非编码RNA(包括microRNAs和lncRNAs)转录后调控肠上皮屏障功能的研究进展。其中,miR-503、miR-146和lnc-uc.173、lnc-SPRY4-IT1、lnc-plncRNA1、lnc-Gata6等,能够促进肠黏膜的更新,增强上皮屏障功能;相反,miR-222、miR-29b、miR-195和lnc-H19与lnc-BC012900等,抑制肠上皮再生并破坏肠上皮屏障功能。miRNAs、mRNAs与lncRNAs间构成复杂的分子网络,共同调控肠上皮稳态。深入研究与肠上皮相关的miRNAs和IncRNAs分子及其作用机制,探寻引起肠黏膜炎症的关键分子靶标,为肠道炎症临床诊治提供新方向与新方法。 相似文献
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13.
Neha Chauhan Gongshe Han Niranjanakumari Somashekarappa Kenneth Gable Teresa Dunn Sepp D. Kohlwein 《The Journal of biological chemistry》2016,291(5):2524-2534
Sphingolipid (SL) biosynthesis is negatively regulated by the highly conserved endoplasmic reticulum-localized Orm family proteins. Defective SL synthesis in Saccharomyces cerevisiae leads to increased phosphorylation and inhibition of Orm proteins by the kinase Ypk1. Here we present evidence that the yeast morphogenesis checkpoint kinase, Swe1, regulates SL biosynthesis independent of the Ypk1 pathway. Deletion of the Swe1 kinase renders mutant cells sensitive to serine palmitoyltransferase inhibition due to impaired sphingoid long-chain base synthesis. Based on these data and previous results, we suggest that Swe1 kinase perceives alterations in SL homeostasis, activates SL synthesis, and may thus represent the missing regulatory link that controls the SL rheostat during the cell cycle. 相似文献
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16.
Ying Chen Hai-Sheng Zhang Guo-Hua Fong Qiu-Lei Xi Guo-Hao Wu Chen-Guang Bai Zhi-Qiang Ling Li Fan Yi-Ming Xu Yan-Qing Qin Tang-Long Yuan Heng Sun Jing Fang 《The Journal of biological chemistry》2015,290(33):20580-20589
Prolyl hydroxylase domain proteins (PHDs) control cellular adaptation to hypoxia. PHDs are found involved in inflammatory bowel disease (IBD); however, the exact role of PHD3, a member of the PHD family, in IBD remains unknown. We show here that PHD3 plays a critical role in maintaining intestinal epithelial barrier function. We found that genetic ablation of Phd3 in intestinal epithelial cells led to spontaneous colitis in mice. Deletion of PHD3 decreases the level of tight junction protein occludin, leading to a failure of intestinal epithelial barrier function. Further studies indicate that PHD3 stabilizes occludin by preventing the interaction between the E3 ligase Itch and occludin, in a hydroxylase-independent manner. Examination of biopsy of human ulcerative colitis patients indicates that PHD3 is decreased with disease severity, indicating that PHD3 down-regulation is associated with progression of this disease. We show that PHD3 protects intestinal epithelial barrier function and reveal a hydroxylase-independent function of PHD3 in stabilizing occludin. These findings may help open avenues for developing a therapeutic strategy for IBD. 相似文献
17.
Xinwei Mu Chen Pan Shuyun Zheng Yasir Alhamdi Bingwei Sun Qiankun Shi Xiang Wang Zhiwei Sun Chenghock Toh Guozheng Wang 《PloS one》2014,9(8)
Objective
To investigate the protective effects and mechanisms of carbon monoxide-releasing molecule-2 (CORM-2) on barrier function of intestinal epithelial cells.Materials and Methods
After pre-incubation with CORM-2 for 1 hour, cultured intestinal epithelial IEC-6 cells were stimulated with 50 µg/ml lipopolysaccharides (LPS). Cytokines levels in culture medium were detected using ELISA kits. Trans-epithelial electrical resistance (TER) of IEC-6 cell monolayers in Transwells were measured with a Millipore electric resistance system (ERS-2; Millipore) and calculated as Ω/cm2 at different time points after LPS treatment. The permeability changes were also measured using FITC-dextran. The levels of tight junction (TJ) proteins (occludin and ZO-1) and myosin light chain (MLC) phosphorylation were detected using Western blotting with specific antibodies. The subsequent structural changes of TJ were visualized using transmission electron microscopy (TEM).Results
CORM-2 significantly reduced LPS-induced secretion of TNF-α and IL-1β. The LPS-induced decrease of TER and increase of permeability to FITC-dextran were inhibited by CORM-2 in a concentration dependent manner (P<0.05). LPS-induced reduction of tight junction proteins and increase of MLC phosphorylation were also attenuated. In LPS-treated cells, TEM showed diminished electron-dense material and interruption of TJ and desmosomes between the apical lateral margins of adjoining cells, which were prevented by CORM-2 treatment.Conclusions
The present study demonstrates that CORM-2, as a novel CO-releasing molecule, has ability to protect the barrier function of LPS-stimulated intestinal epithelial cells. Inhibition of inflammatory cytokines release, restoration of TJ proteins and suppression of MLC phosphorylation are among the protective effects of CORM-2. 相似文献18.
Chen C. Tai Ching Y. Chen Hsuan S. Lee Ya C. Wang Tsai K. Li Harry J. Mersamm Shih T. Ding Pei H. Wang 《The Journal of biological chemistry》2009,284(47):32239-32247
Serum amyloid A (SAA) reduces fat deposition in adipocytes and hepatoma cells. Human SAA1 mRNA is increased by docosahexaenoic acid (DHA) treatment in human cells. These studies asked whether DHA decreases fat deposition through SAA1 and explored the mechanisms involved. We demonstrated that DHA increased human SAA1 and C/EBPβ mRNA expression in human hepatoma cells, SK-HEP-1. Utilizing a promoter deletion assay, we found that a CCAAT/enhancer-binding protein β (C/EBPβ)-binding site in the SAA1 promoter region between −242 and −102 bp was critical for DHA-mediated SAA1 expression. Mutation of the putative C/EBPβ-binding site suppressed the DHA-induced SAA1 promoter activity. The addition of the protein kinase A inhibitor H89 negated the DHA-induced increase in C/EBPβ protein expression. The up-regulation of SAA1 mRNA and protein by DHA was also inhibited by H89. We also demonstrated that DHA increased protein kinase A (PKA) activities. These data suggest that C/EBPβ is involved in the DHA-regulated increase in SAA1 expression via PKA-dependent mechanisms. Furthermore, the suppressive effect of DHA on triacylglycerol accumulation was abolished by H89 in SK-HEP-1 cells and adipocytes, indicating that DHA also reduces lipid accumulation via PKA. The observation of increased SAA1 expression coupled with reduced fat accumulation mediated by DHA via PKA suggests that SAA1 is involved in DHA-induced triacylglycerol breakdown. These findings provide new insights into the complicated regulatory network in DHA-mediated lipid metabolism and are useful in developing new approaches to reduce body fat deposition and fatty liver. 相似文献
19.
《Cell cycle (Georgetown, Tex.)》2013,12(21):2484-2488
Polo-like kinase 1 (Plk1), the best characterized member of the mammalian polo-like kinase family, is well regulated throughout the cell cycle, and is inhibited following DNA damage. Chk1 plays a key role in the response to DNA damage. We recently reported that Chk1 is required for mitotic progression through negative regulation of Plk1. Here, we report the phenotypes of cultured cells upon ectopic expression of various forms of Plk1. Epitopic expression of Plk1 led to mitotic arrest, whereas co-expression of Chk1 could release this mitotic block. Moreover, the Plk1 expression-induced mitotic block was also released by inactivation of the spindle-assembly checkpoint. 相似文献