Gelatinases matrix metalloproteinase-2 and matrix metalloproteinase-9 have been shown to mediate claudin-5 and occludin degradation, and play an important regulatory role in blood-brain barrier permeability. This stud...Gelatinases matrix metalloproteinase-2 and matrix metalloproteinase-9 have been shown to mediate claudin-5 and occludin degradation, and play an important regulatory role in blood-brain barrier permeability. This study established a rat model of 1.5-hour middle cerebral artery occlusion with reperfusion. Protein expression levels of claudin-5 and occludin gradually decreased in the early stage of reperfusion, which corresponded to the increase of the gelatinolytic activity of matrix metalloproteinase-2 and matrix metalloproteinase-9. In addition, rats that received treatment with matrix metalloproteinase inhibitor N-[（2R）-2-（hydroxamidocarbonylmethyl）-4-methylpenthanoyl]-L- tryptophan methylamide （GM6001） showed a significant reduction in Evans blue leakage and an inhibition of claudin-5 and occludin protein degradation in striatal tissue. These data indicate that matrix metalloproteinase-2 and matrix metalloproteinase-9-mediated claudin-5 and occludin degradation is an important reason for blood-brain barrier leakage in the early stage of reperfusion. The leakage of the blood-brain barrier was present due to gelatinases-mediated degradation of claudin-5 and occludin proteins. We hypothesized that the timely closure of the structural component of the blood-brain barrier （tight junction proteins） is of importance.展开更多
AIM： To investigate the influence of experimental obstructive jaundice and exogenous bombesin （BBS） and neurotensin （NT） administration on the expression of the tight junction （TJ）-protein claudin-4 in intestin...AIM： To investigate the influence of experimental obstructive jaundice and exogenous bombesin （BBS） and neurotensin （NT） administration on the expression of the tight junction （TJ）-protein claudin-4 in intestinal epithelium of rats. METHODS： Forty male Wistar rats were randomly divided into five groups： Ⅰ = controls, Ⅱ = sham operated,Ⅲ = bile duct ligation （BDL）,Ⅳ = BDL＋BBS （30μg/kg per d）, V = BDL＋NT （300μg/kg per d）. At the end of the experiment on d 10, endotoxin was measured in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and immunohistochemically for evaluation of claudin-4 expression in intestinal epithelium. RESULTS： Obstructive jaundice led to intestinal barrier failure demonstrated by significant portal and aortic endotoxemia. Claudin-4 expression was significantly increased in the upper third of the villi in jaundiced rats and an upregulation of its lateral distribution was noted. Administration of BBS or NT restored claudin-4 expression to the control state and significantly reduced portal and aortic endotoxemia. CONCLUSION： Experimental obstructive jaundice increases claudin-4 expression in intestinal epithelium,which may be a key factor contributing to the disruption of the mucosal barrier. Gut regulatory peptides BBS and NT can prevent this alteration and reduce portal and systemic endotoxemia.展开更多
AIM To investigate the effects of Clostridium perfringens enterotoxin(CPE) on gastric cancer cells which highly expressed claudin-4(CL4) protein.METHODS In this study, we detected expression of CL4 protein in differen...AIM To investigate the effects of Clostridium perfringens enterotoxin(CPE) on gastric cancer cells which highly expressed claudin-4(CL4) protein.METHODS In this study, we detected expression of CL4 protein in different gastric cancer cell lines. Then, we investigated the effects of CPE on SGC7901 cells which highly expressed CL4 protein and the effects of CPE on sub-cutaneous tumor in nude mice models.RESULTS CL4 are highly expressed in SGC7901 cells. CPE expressedsignificant cytotoxicity in SGC7901 cells. Suppression of CL4 expression significantly decreased CPE-mediated cytotoxicity. CPE also inhibited tumor growth in subcutaneous tumor xenograft models.CONCLUSION CPE showed CL4 mediated cytotoxicity on gastric cancer cells SGC7901 and inhib-ited tumor growth in nude mice models.展开更多
The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated clau...The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.展开更多
Formation of claudin-10 based tight junctions(TJs)is paramount to paracellular Na+transport in multiple epithelia.Sequence variants in CLDN10 have been linked to HELIX syndrome,a salt-losing tubulopathy with altered h...Formation of claudin-10 based tight junctions(TJs)is paramount to paracellular Na+transport in multiple epithelia.Sequence variants in CLDN10 have been linked to HELIX syndrome,a salt-losing tubulopathy with altered handling of divalent cations accompanied by dysfunctional salivary,sweat,and lacrimal glands.Here,we investigate molecular basis and phenotypic consequences of a newly identified homozygous CLDN10 variant that translates into a single amino acid substitution within the fourth transmembrane helix of claudin-10.In addition to hypohidrosis(H),electrolyte(E)imbalance with impaired urine concentrating ability,and hypolacrimia(L),phenotypic findings include altered salivary electrolyte composition and amelogenesis imperfecta but neither ichthyosis(I)nor xerostomia(X).Employing cellular TJ reconstitution assays,we demonstrate perturbation of cis-and trans-interactions between mutant claudin-10 proteins.Ultrastructures of reconstituted TJ strands show disturbed continuity and reduced abundance in the mutant case.Throughout,both major isoforms,claudin-10a and claudin-10b,are differentially affected with claudin-10b showing more severe molecular alterations.However,expression of the mutant in renal epithelial cells with endogenous TJs results in wild-type-like ion selectivity and conductivity,indicating that aberrant claudin-10 is generally capable of forming functional paracellular channels.Thus,mutant proteins prove pathogenic by compromising claudin-10 TJ strand assembly.Additional ex vivo investigations indicate their insertion into TJs to occur in a tissue-specific manner.展开更多
文摘Gelatinases matrix metalloproteinase-2 and matrix metalloproteinase-9 have been shown to mediate claudin-5 and occludin degradation, and play an important regulatory role in blood-brain barrier permeability. This study established a rat model of 1.5-hour middle cerebral artery occlusion with reperfusion. Protein expression levels of claudin-5 and occludin gradually decreased in the early stage of reperfusion, which corresponded to the increase of the gelatinolytic activity of matrix metalloproteinase-2 and matrix metalloproteinase-9. In addition, rats that received treatment with matrix metalloproteinase inhibitor N-[（2R）-2-（hydroxamidocarbonylmethyl）-4-methylpenthanoyl]-L- tryptophan methylamide （GM6001） showed a significant reduction in Evans blue leakage and an inhibition of claudin-5 and occludin protein degradation in striatal tissue. These data indicate that matrix metalloproteinase-2 and matrix metalloproteinase-9-mediated claudin-5 and occludin degradation is an important reason for blood-brain barrier leakage in the early stage of reperfusion. The leakage of the blood-brain barrier was present due to gelatinases-mediated degradation of claudin-5 and occludin proteins. We hypothesized that the timely closure of the structural component of the blood-brain barrier （tight junction proteins） is of importance.
文摘AIM： To investigate the influence of experimental obstructive jaundice and exogenous bombesin （BBS） and neurotensin （NT） administration on the expression of the tight junction （TJ）-protein claudin-4 in intestinal epithelium of rats. METHODS： Forty male Wistar rats were randomly divided into five groups： Ⅰ = controls, Ⅱ = sham operated,Ⅲ = bile duct ligation （BDL）,Ⅳ = BDL＋BBS （30μg/kg per d）, V = BDL＋NT （300μg/kg per d）. At the end of the experiment on d 10, endotoxin was measured in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and immunohistochemically for evaluation of claudin-4 expression in intestinal epithelium. RESULTS： Obstructive jaundice led to intestinal barrier failure demonstrated by significant portal and aortic endotoxemia. Claudin-4 expression was significantly increased in the upper third of the villi in jaundiced rats and an upregulation of its lateral distribution was noted. Administration of BBS or NT restored claudin-4 expression to the control state and significantly reduced portal and aortic endotoxemia. CONCLUSION： Experimental obstructive jaundice increases claudin-4 expression in intestinal epithelium,which may be a key factor contributing to the disruption of the mucosal barrier. Gut regulatory peptides BBS and NT can prevent this alteration and reduce portal and systemic endotoxemia.
基金Supported by The National Natural Science Foundation of China,No.81300268
文摘AIM To investigate the effects of Clostridium perfringens enterotoxin(CPE) on gastric cancer cells which highly expressed claudin-4(CL4) protein.METHODS In this study, we detected expression of CL4 protein in different gastric cancer cell lines. Then, we investigated the effects of CPE on SGC7901 cells which highly expressed CL4 protein and the effects of CPE on sub-cutaneous tumor in nude mice models.RESULTS CL4 are highly expressed in SGC7901 cells. CPE expressedsignificant cytotoxicity in SGC7901 cells. Suppression of CL4 expression significantly decreased CPE-mediated cytotoxicity. CPE also inhibited tumor growth in subcutaneous tumor xenograft models.CONCLUSION CPE showed CL4 mediated cytotoxicity on gastric cancer cells SGC7901 and inhib-ited tumor growth in nude mice models.
文摘The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.
基金supported by Deutsche Forschungsgemeinschaft(DFG)grants(No.GU 447/14-1,14-2 to DG,PI 837/4-1,4-2 to JP,and(No.HA 6908/2-1 to JH,respectively)by Else Kroner-Fresenius-Stiftung grant(No.2016_A52 to JH)+3 种基金JH receives additional funding from the DFG(No.6908/3-1)CB is an employee of Limbach and holds a part-time faculty appointment at the University of FreiburgHis research laboratory receives support from the DFG(No.BE 3910/8-1 and BE 3910/9-1)from the Federal Ministry of Education and Research(BMBF,No.01GM1903I and 01GM1903G).
文摘Formation of claudin-10 based tight junctions(TJs)is paramount to paracellular Na+transport in multiple epithelia.Sequence variants in CLDN10 have been linked to HELIX syndrome,a salt-losing tubulopathy with altered handling of divalent cations accompanied by dysfunctional salivary,sweat,and lacrimal glands.Here,we investigate molecular basis and phenotypic consequences of a newly identified homozygous CLDN10 variant that translates into a single amino acid substitution within the fourth transmembrane helix of claudin-10.In addition to hypohidrosis(H),electrolyte(E)imbalance with impaired urine concentrating ability,and hypolacrimia(L),phenotypic findings include altered salivary electrolyte composition and amelogenesis imperfecta but neither ichthyosis(I)nor xerostomia(X).Employing cellular TJ reconstitution assays,we demonstrate perturbation of cis-and trans-interactions between mutant claudin-10 proteins.Ultrastructures of reconstituted TJ strands show disturbed continuity and reduced abundance in the mutant case.Throughout,both major isoforms,claudin-10a and claudin-10b,are differentially affected with claudin-10b showing more severe molecular alterations.However,expression of the mutant in renal epithelial cells with endogenous TJs results in wild-type-like ion selectivity and conductivity,indicating that aberrant claudin-10 is generally capable of forming functional paracellular channels.Thus,mutant proteins prove pathogenic by compromising claudin-10 TJ strand assembly.Additional ex vivo investigations indicate their insertion into TJs to occur in a tissue-specific manner.
