131 results on '"Hang Thi Thu Nguyen"'
Search Results
102. Tri-Dap Interacts Directly With the Lrr Domain of NOD1 and Consequently Regulates Rick/NOD1 Interactions
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Shanthi V. Sitaraman, Saravanan Ayyadurai, Guillaume Dalmasso, Moiz A. Charania, Hamed Laroui, Didier Merlin, Yutao Yan, and Hang Thi Thu Nguyen
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Physics ,Hepatology ,NOD1 ,Gastroenterology ,Domain (software engineering) ,Cell biology - Published
- 2011
103. Overexpression of PepT1 Increases the Susceptibility of Mice to Colitis in a Process Involving NOD2 Activity
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Yutao Yan, Saravanan Ayyadurai, Moiz A. Charania, Guillaume Dalmasso, Hang Thi Thu Nguyen, Shanthi V. Sitaraman, Didier Merlin, and Hamed Laroui
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Hepatology ,Chemistry ,NOD2 ,Gastroenterology ,medicine ,Cancer research ,Colitis ,medicine.disease - Published
- 2011
104. Intestinal Epithelial Cell-Specific CD98 Overexpression Enhances Tumorigenesis in APC(MIN/+) Mice
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Hang Thi Thu Nguyen, Didier Merlin, Yutao Yan, Shanthi V. Sitaraman, Saravanan Ayyadurai, Moiz A. Charania, Guillaume Dalmasso, and Hamed Laroui
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Min mice ,CD98 ,medicine.anatomical_structure ,Hepatology ,biology ,Chemistry ,Gastroenterology ,Cancer research ,medicine ,biology.protein ,Carcinogenesis ,medicine.disease_cause ,Epithelium - Published
- 2011
105. S1714 STE20-Related Proline/Alanine-Rich Kinase (SPAK) is Involved in Intestinal Barrier Dysfunction in the Pathogenesis of Inflammatory Bowel Diseases (IBD)
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Shanthi V. Sitaraman, Hang Thi Thu Nguyen, Guillaume Dalmasso, Didier Merlin, Yutao Yan, and Tracy S. Obertone
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Alanine ,Pathogenesis ,Hepatology ,business.industry ,Kinase ,Gastroenterology ,Inflammatory Bowel Diseases ,Medicine ,Proline ,Pharmacology ,business - Published
- 2010
106. W1340 A Novel Approach for Gene Therapy in IBD
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Didier Merlin, Shanthi V. Sitaraman, Hamed Laroui, Guillaume Dalmasso, Hang Thi Thu Nguyen, and Yutao Yan
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Hepatology ,business.industry ,Genetic enhancement ,Gastroenterology ,Medicine ,business ,Bioinformatics - Published
- 2010
107. 258 PepT1 Mediates Transport of the Pro-Inflammatory Tripeptide L-Ala-γ-D-Glu-Meso-Dap in Intestinal Epithelial Cells
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Didier Merlin, Shanthi V. Sitaraman, Hamed Laroui, Guillaume Dalmasso, Laetitia Charrier-Hisamuddin, Hang Thi Thu Nguyen, and Yutao Yan
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Interleukin 22 ,Hepatology ,Chemistry ,Gastroenterology ,Tripeptide ,Molecular biology - Published
- 2010
108. Pathogenic Bacteria Induce Colonic PepT1 Expression: An Implication in Host Defense Response
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Shanthi V. Sitaraman, Didier Merlin, Kimberly R. Powell, Daniel Kalman, Hang Thi Thu Nguyen, Guillaume Dalmasso, Yutao Yan, and Shantanu Bhatt
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Genetically modified mouse ,Time Factors ,Transcription, Genetic ,Colon ,Mice, Transgenic ,Biology ,Transfection ,medicine.disease_cause ,Peptide Transporter 1 ,digestive system ,Bacterial Adhesion ,Article ,Proinflammatory cytokine ,Microbiology ,Enteropathogenic Escherichia coli ,Mice ,Membrane Microdomains ,medicine ,Citrobacter rodentium ,Animals ,Humans ,CDX2 Transcription Factor ,RNA, Messenger ,Intestinal Mucosa ,Promoter Regions, Genetic ,Protein kinase A ,Lipid raft ,Homeodomain Proteins ,Symporters ,Hepatology ,Interleukin-8 ,NF-kappa B ,Gastroenterology ,Pathogenic bacteria ,Colitis ,digestive system diseases ,Disease Models, Animal ,Neutrophil Infiltration ,Inflammation Mediators ,Mitogen-Activated Protein Kinases ,HT29 Cells ,Ex vivo - Abstract
Background & Aims Expression of the di/tripeptide transporter PepT1 has been observed in the colon under inflammatory conditions; however, the inducing factors and underlying mechanisms remain unknown. Here, we address the effects of pathogenic bacteria on colonic PepT1 expression together with its functional consequences. Methods Human colonic HT29-Cl.19A cells were infected with the attaching and effacing enteropathogenic Escherichia coli (EPEC). Wild-type and PepT1 transgenic mice or cultured colonic tissues derived from these mice were infected with Citrobacter rodentium , a murine attaching and effacing pathogen related to EPEC. Results EPEC induced PepT1 expression and activity in HT29-Cl.19A cells by intimately attaching to host cells through lipid rafts. Induction of PepT1 expression by EPEC required the transcription factor Cdx2. PepT1 expression reduced binding of EPEC to lipid rafts, as well as activation of nuclear factor-κB and mitogen-activated protein kinase and production of interleukin-8. Accordingly, ex vivo and in vivo experiments revealed that C rodentium induced colonic PepT1 expression and that, compared with their wild-type counterparts, PepT1 transgenic mice infected with C rodentium exhibited decreased bacterial colonization, production of proinflammatory cytokines, and neutrophil infiltration into the colon. Conclusions Our findings demonstrate a molecular mechanism underlying the regulation of colonic PepT1 expression under pathologic conditions and reveal a novel role for PepT1 in host defense via its capacity to modulate bacterial-epithelial interactions and intestinal inflammation.
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- 2009
109. 214 Expression of hPepT1 Aggravates Intestinal Inflammation
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Shanthi V. Sitaraman, Didier Merlin, Mauricio Rojas, Guillaume Dalmasso, Yutao Yan, and Hang Thi Thu Nguyen
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Hepatology ,Expression (architecture) ,Intestinal inflammation ,business.industry ,Gastroenterology ,Cancer research ,Medicine ,business - Published
- 2009
110. T1707 STE20-Related Proline/Alanine-Rich Kinase (SPAK) Regulated Transcriptionally By Hyperosmolarity Is Involved in Intestinal Barrier Function
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Guillaume Dalmasso, Tracy S. Obertone, Yutao Yan, Shanthi V. Sitaraman, Hang Thi Thu Nguyen, and Didier Merlin
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Alanine ,Hepatology ,Osmotic concentration ,Biochemistry ,Chemistry ,Kinase ,Gastroenterology ,Proline ,Barrier function - Published
- 2009
111. S1770 MiR-619 Regulates Expression of the Intestinal Oligopeptide Membrane Transporter PepT1
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Hang Thi Thu Nguyen, Shanthi V. Sitaraman, Guillaume Dalmasso, Yutao Yan, and Didier Merlin
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Oligopeptide ,Membrane ,Hepatology ,Chemistry ,Gastroenterology ,Transporter ,Cell biology - Published
- 2009
112. W1598 CD98 Regulates Cell-Cell Interactions Through Its Extracellular Phosphorylation
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Shanthi V. Sitaraman, Hang Thi Thu Nguyen, Guillaume Dalmasso, Didier Merlin, Tracy S. Obertone, and Yutao Yan
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CD98 ,medicine.anatomical_structure ,Hepatology ,biology ,Chemistry ,Cell ,Gastroenterology ,biology.protein ,medicine ,Extracellular ,Phosphorylation ,Cell biology - Published
- 2009
113. 556 Pathogenic Bacteria Transcriptionally Induce Colonic PepT1 Expression – An Implication in Modulating Bacterial-Epithelial Interaction
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Daniel Kalman, Andrew T. Gewirtz, Guillaume Dalmasso, Kim Powell, Didier Merlin, Yutao Yan, Shanthi V. Sitaraman, Shantanu Bhatt, and Hang Thi Thu Nguyen
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Hepatology ,Gastroenterology ,medicine ,Pathogenic bacteria ,Biology ,medicine.disease_cause ,Microbiology - Published
- 2009
114. Ste20-Related Proline/Alanine-Rich Kinase (SPAK) Regulated Transcriptionally by Hyperosmolarity Is Involved in Intestinal Barrier Function
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Guillaume Dalmasso, Hang Thi Thu Nguyen, Didier Merlin, Shanthi V. Sitaraman, Yutao Yan, and Tracy S. Obertone
- Subjects
Transcription, Genetic ,Colon ,Sp1 Transcription Factor ,Cellular differentiation ,lcsh:Medicine ,Mice, Transgenic ,Protein Serine-Threonine Kinases ,Biology ,Mice ,03 medical and health sciences ,Crohn Disease ,Downregulation and upregulation ,Intestinal mucosa ,Animals ,Humans ,Intestinal Mucosa ,RNA, Small Interfering ,Promoter Regions, Genetic ,lcsh:Science ,Barrier function ,030304 developmental biology ,0303 health sciences ,Gene knockdown ,Sp1 transcription factor ,Gastroenterology and Hepatology/Inflammatory Bowel Disease ,Binding Sites ,Multidisciplinary ,Kinase ,Osmolar Concentration ,lcsh:R ,030302 biochemistry & molecular biology ,NF-kappa B ,NFKB1 ,Molecular biology ,Pathology/Molecular Pathology ,Pathology/Pathophysiology ,Mice, Inbred C57BL ,Gene Knockdown Techniques ,lcsh:Q ,Caco-2 Cells ,Research Article - Abstract
The Ste20-related protein proline/alanine-rich kinase (SPAK) plays important roles in cellular functions such as cell differentiation and regulation of chloride transport, but its roles in pathogenesis of intestinal inflammation remain largely unknown. Here we report significantly increased SPAK expression levels in hyperosmotic environments, such as mucosal biopsy samples from patients with Crohn's disease, as well as colon tissues of C57BL/6 mice and Caco2-BBE cells treated with hyperosmotic medium. NF-kappaB and Sp1-binding sites in the SPAK TATA-less promoter are essential for SPAK mRNA transcription. Hyperosmolarity increases the ability of NF-kappaB and Sp1 to bind to their binding sites. Knock-down of either NF-kappaB or Sp1 by siRNA reduces the hyperosmolarity-induced SPAK expression levels. Furthermore, expression of NF-kappaB, but not Sp1, was upregulated by hyperosmolarity in vivo and in vitro. Nuclear run-on assays showed that hyperosmolarity increases SPAK expression levels at the transcriptional level, without affecting SPAK mRNA stability. Knockdown of SPAK expression by siRNA or overexpression of SPAK in cells and transgenic mice shows that SPAK is involved in intestinal permeability in vitro and in vivo. Together, our data suggest that SPAK, the transcription of which is regulated by hyperosmolarity, plays an important role in epithelial barrier function.
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- 2009
115. Butyrate Transcriptionally Enhances Peptide Transporter PepT1 Expression and Activity
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Shanthi V. Sitaraman, Laetitia Charrier-Hisamuddin, Guillaume Dalmasso, Yutao Yan, Hang Thi Thu Nguyen, and Didier Merlin
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Chromatin Immunoprecipitation ,Transcription, Genetic ,Science ,Blotting, Western ,Butyrate ,Peptide Transporter 1 ,Histones ,Butyric acid ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Western blot ,Gene expression ,medicine ,Humans ,CDX2 Transcription Factor ,RNA, Messenger ,Promoter Regions, Genetic ,CDX2 ,Molecular Biology ,030304 developmental biology ,Homeodomain Proteins ,0303 health sciences ,Binding Sites ,Gastroenterology and Hepatology/Inflammatory Bowel Disease ,Multidisciplinary ,Symporters ,biology ,medicine.diagnostic_test ,Reverse Transcriptase Polymerase Chain Reaction ,Peptide transporter 1 ,Acetylation ,Cell Biology ,Molecular biology ,6. Clean water ,3. Good health ,Blot ,Enhancer Elements, Genetic ,chemistry ,Caco-2 ,Molecular Biology/Post-Translational Regulation of Gene Expression ,biology.protein ,Butyric Acid ,Medicine ,030211 gastroenterology & hepatology ,Caco-2 Cells ,Research Article - Abstract
BackgroundPepT1, an intestinal epithelial apical di/tripeptide transporter, is normally expressed in the small intestine and induced in colon during chronic inflammation. This study aimed at investigating PepT1 regulation by butyrate, a short-chain fatty acid produced by commensal bacteria and accumulated inside inflamed colonocyte.ResultsWe found that butyrate treatment of human intestinal epithelial Caco2-BBE cells increased human PepT1 (hPepT1) promoter activity in a dose- and time-dependent manner, with maximal activity observed in cells treated with 5 mM butyrate for 24 h. Under this condition, hPepT1 promoter activity, mRNA and protein expression levels were increased as assessed by luciferase assay, real-time RT-PCR and Western blot, respectively. hPepT1 transport activity was accordingly increased by approximately 2.5-fold. Butyrate did not alter hPepT1 mRNA half-life indicating that butyrate acts at the transcriptional level. Molecular analyses revealed that Cdx2 is the most important transcription factor for butyrate-induced increase of hPepT1 expression and activity in Caco2-BBE cells. Butyrate-activated Cdx2 binding to hPepT1 promoter was confirmed by gel shift and chromatin immunoprecipitation. Moreover, Caco2-BBE cells overexpressing Cdx2 exhibited greater hPepT1 expression level than wild-type cells. Finally, treatment of mice with 5 mM butyrate added to drinking water for 24 h increased colonic PepT1 mRNA and protein expression levels, as well as enhanced PepT1 transport activity in colonic apical membranes vesicles.ConclusionsCollectively, our results demonstrate that butyrate increases PepT1 expression and activity in colonic epithelial cells, which provides a new understanding of PepT1 regulation during chronic inflammation.
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- 2008
116. M1687 Ecto-Phosphorylation of CD98 Regulates Lymphocytes-Epithelia Interactions
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Hang Thi Thu Nguyen, Guillaume Dalmasso, Yutao Yan, Didier Merlin, Laetitia Charrier-Hisammudin, and Shanthi V. Sitaraman
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CD98 ,Hepatology ,biology ,Chemistry ,Gastroenterology ,biology.protein ,Phosphorylation ,Cell biology - Published
- 2008
117. 397 Colonic STE20-Related Protein Kinase Isoform (SPAK): A Novel Regulator of Intestinal Inflammation
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Shanthi V. Sitaraman, Didier Merlin, Guillaume Dalmasso, Yutao Yan, Hang Thi Thu Nguyen, and Laetitia Charrier-Hisamuddin
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Gene isoform ,Hepatology ,Intestinal inflammation ,Chemistry ,Gastroenterology ,Regulator ,ASK1 ,Protein kinase A ,Protein kinase R ,Cell biology - Published
- 2008
118. M1166 PepT1 Associated with Lipid Rafts Modulates Bacterial-Epithelial Interactions
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Didier Merlin, Guillaume Dalmasso, Hang Thi Thu Nguyen, and Shanthi V. Sitaraman
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Hepatology ,Chemistry ,Gastroenterology ,Lipid raft ,Cell biology - Published
- 2008
119. Association of PepT1 to lipid rafts determines its activity: implications for intestinal inflammatory response
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Yutao Yan, Didier Merlin, Laetitia Charrier-Hisamuddin, S Sitaraman, Hang Thi Thu Nguyen, and G Dalmasso
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Sucrose ,Chemistry ,Immunoprecipitation ,Gastroenterology ,Aminopeptidase ,Sphingolipid ,Epithelium ,chemistry.chemical_compound ,medicine.anatomical_structure ,Biochemistry ,Glycine ,medicine ,Immunology and Allergy ,Threonine ,Lipid raft - Published
- 2008
120. Human intestinal ste20-related proline/alanine kinase (SPAK): A novel regulator of intestinal inflammation
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Didier Merlin, Yutao Yan, Hang Thi Thu Nguyen, L Charrier, S Sitaraman, and G Dalmasso
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Alanine ,Biochemistry ,Kinase ,Chemistry ,Intestinal inflammation ,Gastroenterology ,Regulator ,Immunology and Allergy ,Proline - Published
- 2008
121. CD98 expression modulates intestinal homeostasis, inflammation, and colitis-associated cancer in mice.
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Hang Thi Thu Nguyen, Dalmasso, Guillaume, Torkvist, Leif, Halfvarson, Jonas, Yutao Yan, Laroui, Hamed, Shmerling, Doron, Tallone, Tiziano, D'Amato, Mauro, Sitaraman, Shanthi V., Merlin, Didier, Nguyen, Hang Thi Thu, and Yan, Yutao
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INFLAMMATORY bowel diseases , *COLON diseases , *COLITIS , *GLYCOPROTEINS , *PHYSIOLOGICAL control systems , *HOMEOSTASIS , *INFLAMMATION , *INTESTINAL diseases , *ANIMAL experimentation , *CELL membranes , *CELL physiology , *COMPARATIVE studies , *GENES , *GENETIC polymorphisms , *INTESTINES , *RESEARCH methodology , *MEDICAL cooperation , *MICE , *RESEARCH , *RESEARCH funding , *TUMORS , *EVALUATION research - Abstract
Expression of the transmembrane glycoprotein CD98 (encoded by SLC3A2) is increased in intestinal inflammatory conditions, such as inflammatory bowel disease (IBD), and in various carcinomas, yet its pathogenetic role remains unknown. By generating gain- and loss-of-function mouse models with genetically manipulated CD98 expression specifically in intestinal epithelial cells (IECs), we explored the role of CD98 in intestinal homeostasis, inflammation, and colitis-associated tumorigenesis. IEC-specific CD98 overexpression induced gut homeostatic defects and increased inflammatory responses to DSS-induced colitis, promoting colitis-associated tumorigenesis in mice. Further analysis indicated that the ability of IEC-specific CD98 overexpression to induce tumorigenesis was linked to its capacity to induce barrier dysfunction and to stimulate cell proliferation and production of proinflammatory mediators. To validate these results, we constructed mice carrying conditional floxed Slc3a2 alleles and crossed them with Villin-Cre mice such that CD98 was downregulated only in IECs. These mice exhibited attenuated inflammatory responses and resistance to both DSS-induced colitis and colitis-associated tumorigenesis. Together, our data show that intestinal CD98 expression has a crucial role in controlling homeostatic and innate immune responses in the gut. Modulation of CD98 expression in IECs therefore represents a promising therapeutic strategy for the treatment and prevention of inflammatory intestinal diseases, such as IBD and colitis-associated cancer. [ABSTRACT FROM AUTHOR]
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- 2011
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122. Microbiota Modulate Host Gene Expression via MicroRNAs.
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Dalmasso, Guillaume, Hang Thi Thu Nguyen, Yan, Yutao, Laroui, Hamed, Charania, Moiz A., Ayyadurai, Saravanan, Sitaraman, Shanthi V., and Merlin, Didier
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GENE expression , *RNA , *MACROPHAGES , *CELL culture , *CELL lines - Abstract
Microbiota are known to modulate host gene expression, yet the underlying molecular mechanisms remain elusive. MicroRNAs (miRNAs) are importantly implicated in many cellular functions by post-transcriptionally regulating gene expression via binding to the 3′-untranslated regions (39-UTRs) of the target mRNAs. However, a role for miRNAs in microbiota-host interactions remains unknown. Here we investigated if miRNAs are involved in microbiota-mediated regulation of host gene expression. Germ-free mice were colonized with the microbiota from pathogen-free mice. Comparative profiling of miRNA expression using miRNA arrays revealed one and eight miRNAs that were differently expressed in the ileum and the colon, respectively, of colonized mice relative to germ-free mice. A computational approach was then employed to predict genes that were potentially targeted by the dysregulated miRNAs during colonization. Overlapping the miRNA potential targets with the microbiota-induced dysregulated genes detected by a DNA microarray performed in parallel revealed several host genes that were regulated by miRNAs in response to colonization. Among them, Abcc3 was identified as a highly potential miRNA target during colonization. Using the murine macrophage RAW 264.7 cell line, we demonstrated that mmu-miR-665, which was dysregulated during colonization, down-regulated Abcc3 expression by directly targeting the Abcc3 3′-UTR. In conclusion, our study demonstrates that microbiota modulate host microRNA expression, which could in turn regulate host gene expression. [ABSTRACT FROM AUTHOR]
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- 2011
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123. MicroRNA-92b regulates expression of the oligopeptide transporter PepT1 in intestinal epithelial cells.
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Dalmasso, Guillaume, Hang Thi Thu Nguyen, Yutao Yan, Laroui, Hamed, Charania, Moiz A., Obertone, Tracy S., Sitaraman, Shanthi V., and Merlin, Didier
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RNA , *GENE expression , *CELL physiology , *CELL differentiation , *SMALL intestine , *EPITHELIAL cells - Abstract
MicroRNAs (miRNAs), which are noncoding RNAs that posttranscriptionally inhibit expression of target genes, have recently emerged as important regulators of many cellular functions such as cell differentiation. The epithelial di/tripeptide membrane transporter PepT1 is expressed in highly differentiated cells (the villous tip) but not in undifferentiated cells (the crypt) of the small intestine. Here, we investigated the regulation of PepT1 expression by miRNAs and its functional consequences. We observed a reverse correlation between the expression levels of PepT1 and mature miRNA-92b (miR-92b) during the differentiation of intestinal epithelial Caco2-BBE cells, suggesting a miR-92b-mediated regulation of PepT1 expression. We demonstrate that miR-92b suppressed PepT1 expression at both mRNA and protein levels, with subsequent reduced PepT1 transport activity, in Caco2-BBE cells by directly targeting the PepT1 3'-untranslated region. In addition, miR-92b suppresses bacterial peptide-induced proinflammatory responses in intestinal epithelial cells by inhibiting PepT1 expression. Altogether, our study provides for the first time evidence for the regulation of PepT1 expression at a posttranscriptional level by miRNAs in intestinal epithelial cells during pathophysiological states. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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124. PepT1 mediates transport of the proinflammatory bacterial tripeptide L-Ala-γ-D-Glu-meso-DAP in intestinal epithelial cells.
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Dalmasso, Guillaume, Hang Thi Thu Nguyen, Charrier-Hisamuddin, Laetitia, Yutao Yan, Laroui, Hamed, Demoulin, Benjamin, Sitaraman, Shanthi V., and Merlin, Didier
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INFLAMMATORY bowel diseases , *INFLAMMATION , *GASTROENTERITIS , *INTESTINAL diseases , *PEPTIDES , *CYTOKINES , *INTERLEUKIN-8 - Abstract
PepT1 is a di/tripeptide transporter highly expressed in the small intestine, but poorly or not expressed in the colon. However, dt, ring chronic inflammation, such as inflammatory bowel disease. PepT1 expression is induced in the colon. Commensal bacteria that colonize the human colon produce a large amount of di/tripeptides. To date, two bacterial peptides (N-formylmethionylleucyl-phenylalanine and muramyl dipeptide) have been identified as substrates of PepT1. We hypothesized that the proinflarnmatory tripeptide L-Ala-γ-D-Glu-meso-DAP (Tri-DAP), a breakdown product of bacterial peptidoglycan, is transported into intestinal epithelial cells via PepT1. We found that uptake of glycine-sarcosine, a specific substrate of PepT1, in intestinal epithelial Caco2-BBE cells was inhibited by Tri-DAP in a dose-dependent manner. Tri-DAP induced activation of NF-κB and MAP kinases, consequently leading to production of the proinflammatory cytokine interleukin-8. Tri-DAP induced inflammatory response in Caco2-BBE cells was significantly suppressed by silencing of PepT1 expression by using PepT1-shRNAs in a tetracycline-regulated expression (Tet-off) system. Colonic epithelial HT29-Cl.19A cells, which do not express PepT1 under basal condition, were mostly insensitive to Tri-DAP-induced inflammation. However, HT29-Cl.19A cells exhibited proinflammatory response to Tri-DAP upon stable transfection with a plasmid encoding PepT1. Accordingly, Tri-DAP significantly increased keratinocyte-derived chemokine production in colonic tissues from transgenic mice expressing PepT1 in intestinal epithelial ceils. Finally, Tri-DAP induced a significant drop in intracellular pH in intestinal epithelial cells expressing PepT1. but not in cells that did not express PepT1. Our data collectively support the classification of Tri-DAP as a novel substrate of PepT1. Given that PepT1 is highly expressed in the colon during inflammation, PepTl-mediated Tri-DAP transport may occur more effectively during such conditions, further contributing to intestinal inflammation. [ABSTRACT FROM AUTHOR]
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- 2010
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125. MicroRNA-7 Modulates CD98 Expression during Intestinal Epithelial Cell Differentiation.
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Hang Thi Thu Nguyen, Dalmasso, Guillaume, Yutao Yan, Laroui, Hamed, Dahan, Stephanie, Mayer, Lloyd, Sitaraman, Shanthi V., and Merlin, Didier
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MICRORNA , *GENETIC regulation , *EPITHELIAL cells , *CROHN'S disease diagnosis , *CELL differentiation , *GLYCOPROTEINS , *CYTOKINES - Abstract
The transmembrane glycoprotein CD98 regulates multiple cellular functions, including extracellular signaling, epithelial cell adhesion/polarity, amino acid transport, and cell-cell interactions. MicroRNAs post-transcriptionally regulate gene expression, thereby functioning as modulators of numerous cellular processes, such as cell differentiation, proliferation, and apoptosis. Here, we investigated if microRNAs regulate CD98 expression during intestinal epithelial cell differentiation and inflammation. We found that microRNA-7 repressed CD98 expression in Caco2-BBE cells by directly targeting the 3'-untranslated region of human CD98 mRNA. Expression of CD98 was decreased, whereas that of microRNA-7 was increased in well-differentiated Caco2-BBE cells compared with undifferentiated cells. Undifferentiated crypt cells isolated from mouse jejunum showed higher CD98 levels and lower levels of mmumicroRNA-706, a murine original microRNA candidate for CD98, than well-differentiated villus cells. Importantly, microRNA-7 decreased Caco2-BBE cell attachment on laminm-i, and CD98 overexpression recovered this inhibition, suggesting that microRNA-7 modulates epithelial cell adhesion to extracellular matrix, which in turn could affect proliferation and differentiation during the migration of enterocytes across the crypt-villus axis, by regulating CD98 expression. In a pathological context, the pro-inflammatory cytokine interleukin 1-j3 increased CD98 expression in Caco2-BBE cells by decreasing microRNA-7 levels. Consistent with the in vitro findings, microRNA-7 levels were decreased in actively inflamed Crohn disease colonic tissues, where CD98 expression was up-regulated, compared with normal tissues. Together, these results reveal a novel mechanism underlying regulation of CD98 expression during patho-physiological states. This study raises microRNAs as a promising target for therapeutic modulations of CD98 expression in intestinal inflammatory disorders. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
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126. Butyrate Transcriptionally Enhances Peptide Transporter PepT1 Expression and Activity.
- Author
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Dalmasso, Guillaume, Hang Thi Thu Nguyen, Yutao Yan, Charrier-Hisamuddin, Laetitia, Sitaraman, Shanthi V., and Merlin, Didier
- Subjects
- *
PEPTIDES , *GENE expression , *GENETIC transcription , *SMALL intestine diseases , *COLON diseases , *LUCIFERASES , *CHROMATIN , *MICE , *MESSENGER RNA - Abstract
Background: PepT1, an intestinal epithelial apical di/tripeptide transporter, is normally expressed in the small intestine and induced in colon during chronic inflammation. This study aimed at investigating PepT1 regulation by butyrate, a short-chain fatty acid produced by commensal bacteria and accumulated inside inflamed colonocyte. Results: We found that butyrate treatment of human intestinal epithelial Caco2-BBE cells increased human PepT1 (hPepT1) promoter activity in a dose- and time-dependent manner, with maximal activity observed in cells treated with 5 mM butyrate for 24 h. Under this condition, hPepT1 promoter activity, mRNA and protein expression levels were increased as assessed by luciferase assay, real-time RT-PCR and Western blot, respectively. hPepT1 transport activity was accordingly increased by ∼2.5-fold. Butyrate did not alter hPepT1 mRNA half-life indicating that butyrate acts at the transcriptional level. Molecular analyses revealed that Cdx2 is the most important transcription factor for butyrate-induced increase of hPepT1 expression and activity in Caco2-BBE cells. Butyrate-activated Cdx2 binding to hPepT1 promoter was confirmed by gel shift and chromatin immunoprecipitation. Moreover, Caco2-BBE cells overexpressing Cdx2 exhibited greater hPepT1 expression level than wild-type cells. Finally, treatment of mice with 5 mM butyrate added to drinking water for 24 h increased colonic PepT1 mRNA and protein expression levels, as well as enhanced PepT1 transport activity in colonic apical membranes vesicles. Conclusions: Collectively, our results demonstrate that butyrate increases PepT1 expression and activity in colonic epithelial cells, which provides a new understanding of PepT1 regulation during chronic inflammation. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
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127. Association of PepT 1 with lipid rafts differently modulates its transport activity in polarized and nonpolarized cells.
- Author
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Hang Thi Thu Nguyen, Charrier-Hisamuddin, Laetitia, Dalmasso, Guillaume, Hiol, Abel, Sitaraman, Shanthi, and Merlin, Didier
- Subjects
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EPITHELIAL cells , *CELLULAR immunity , *TRANSPLANTATION immunology , *CELL membranes , *GASTROINTESTINAL system , *PHYSIOLOGY - Abstract
The transporter PepT1, apically expressed in intestinal epithelial cells, is responsible for the uptake of di/tripeptides. PepT1 is also expressed in nonpolarized immune cells. Here we investigated the localization of PepT1 in lipid rafts in small intestinal brush border membranes (BBM5) and polarized and nonpolarized cells, as well as functional consequences of the association of PepT1 with lipid rafts. Immunoblot analysis showed the presence of PepT1 in low-density fractions isolated from mouse intestinal BBMs, polarized intestinal Caco2-BBE cells, and nonpolarized Jurkat cells by solubilization in ice-cold 0.5% Triton X-100 and sucrose gradient fractionation. PepT1 colocalized with lipid raft markers GM1 and N-aminopeptidase in intestinal BBMs and Caco2-BBE cell membranes. Disruption of lipid rafts with methyl-β-cyclodextrin (MβCD) shifted PepT1 from low- to high-density fractions. Remarkably, we found that MβCD treatment increased PepT1 transport activity in polarized intestinal epithelia but decreased that in intestinal BBM vesicles and nonpolarized immune cells. Mutational analysis showed that phenylalanine 293, phenylalanine 297, and threonine 281 in transmembrane segment 7 of the human di/tripeptide transporter, hPepT1, are important for the targeting to lipid rafts and transport activity of hPepT1. In conclusion, the association of PepT1 with lipid rafts differently modulates its transport activity in polarized and nonpolarized cells. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
128. Both the RGD sequence and the cytoplasmic tail of ADAM15 are required for homotypic aggregation of T lymphocytes and heterotypic interactions between T lymphocytes and intestinal epithelia.
- Author
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Charrier, Laetitia, Yutao Yan, Hang Thi Thu Nguyen, Dalmasso, Guillaume, Laboisse, Christian L., Gewirtz, Andrew T., Sitaraman, Shanthi V., and Merlin, Didier
- Subjects
AMINO acid sequence ,PROTEINS ,T cells ,EPITHELIAL cells ,INTESTINES ,CELL adhesion ,CELL communication - Abstract
We previously showed that the RGD integrin-binding sequence-containing ADAM15 is expressed in intestinal epithelial cells (IEC). The presence of a RGD-containing disintegrin protein in IEC suggested a potential role of ADAM15 in cell adhesion involving these cells. As already described in NIH3T3 cells, our previous finding of the inhibition of IEC wound-healing by ADAM15 overexpression could-be due to enhanced cell-cell interactions. Therefore, our recent finding of ADAM15 up-regulation during inflammatory bowel disease (IBD) led us to examine the roles of ADAM15 in cell adhesion relevant to IBD. T cell adhesion on IEC was assessed using Jurkat cells and Caco2-BBE monolayers. Our results show that an anti-ADAM15 ectodomain antibody inhibited the binding of Jurkat cells on Caco2-BBE monolayers. Overexpression of ADAM15 in Caco2-BBE cells enhanced Jurkat cells binding and overexpression of ADAM15 in Jurkat cells enhanced homotypic adhesion. Both the mutation of the RGD domain and the deletion of the cytoplasmic tail decreased these cell-cell interactions. Here we demonstrate that 1) ADAM15 is involved in T cell adhesion to IEC as well as T cell aggregation; 2) both the RGD motif and the cytoplasmic tail of ADAM15 are involved for these cell-cell interactions. Altogether these findings point to ADAM15 as a possible. therapeutic target for prevention of inappropriate T cell activation involved in some pathologies. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
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129. The localization of PepT1 in intestinal brush border lipid raft microdomains determines its transport function.
- Author
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Hang Thi Thu Nguyen, Charrier, Laetitia, Sitaraman, Shanthi, and Merlin, Didier
- Subjects
- *
PEPTIDES , *BRUSH border membrane , *CELL membranes , *SMALL intestine , *BIOLOGICAL transport - Abstract
The brush border (BB) of small intestinal enterocytes is a rich source of lipid rafts, which are membrane microdomains that are enriched in cholesterol and glycosphingolipids, and contain some digestive enzymes, trafficking molecules and signaling proteins. The intestinal epithelial apical transporter, hPepT1, is expressed in intestinal epithelial cells, where it is responsible for the uptake of a broad range of small peptides. To examine the mechanism of hPepT1-mediated peptide transport in more detail, we herein investigated the presence of hPepT1 in intestinal lipid rafts. Immunoblotting showed that hPepT1 was enriched in low-density fractions (LDFs; containing the lipid rafts) isolated from mouse intestinal BB and polarized Caco2-BBE cells by detergent extraction and sucrose gradient fractionation. In these fractions, hPepT1 co-localized with N aminopeptidase, a well-known intestinal raft resident, as well as the raft marker, ganglioside GM1. Disruption of lipid rafts by cholesterol depletion with methyl beta cyclodextrin caused hPepT1 to shift from the LDFs to the high-density fractions and decreased the hPepT1-mediated transport activity. Lastly, detergent-insoluble fractions extracted from non-polarized Caco2-BBE cells were almost completely devoid of hPepT1. These findings collectively suggest that hPepT1 is mainly distributed in the lipid rafts from polarized enterocytes, where its activity may be lipid raft-dependent. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
130. ADAM-15/Metargidin Mediates Homotypic Aggregation of Human T Lymphocytes and Heterotypic Interactions of T Lymphocytes with Intestinal Epithelial CelIs.
- Author
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Charrier, Laetitia, Yutao Yan, Hang Thi Thu Nguyen, Dalmasso, Guillaume, Laboisse, Christian L., Gewirtz, Andrew T., Sitaraman, Shanthi V., and Merlin, Didier
- Subjects
- *
EPITHELIAL cells , *IMMUNOREGULATION , *LYMPHOCYTES , *INTESTINAL diseases , *CELL adhesion - Abstract
Intestinal epithelial cells (IEC) play an immunoregulatory role in the intestine. This role involves cell-cell interactions with intraepithelial lymphocytes that may also play a role in some enteropathies. The discovery of the RGD motif-containing protein ADAM-15 (a disintegrin and metalloprotease-15) raises the question of its involvement in these cell-cell interactions. Cell adhesion assays were performed using the Jurkat E6.1T cell line as a model of T lymphocytes and Caco2-BBE monolayers as a model of intestinal epithelia. Our results show that an anti-ADAM-15 ectodomain antibody inhibited the attachment of Jurkat cells on Caco2-BBE monolayers. Overexpression of ADAM-15 in Caco2-BBE cells enhanced Jurkat cell binding, and overexpression of ADAM-15 in Jurkat cells enhanced their aggregation. Mutagenesis experiments showed that both the mutation of ADAM-15 RGD domain or the deletion of its cytoplasmic tail decreased these cell-cell interactions. Moreover, wound-healing experiments showed that epithelial ADAM-15-mediated Jurkat cell adhesion to Caco2-BBE cells enhances the mechanisms of wound repair. We also found that ADAM-15-mediated aggregation of Jurkat cells increases the expression of tumor necrosis factor-α mRNA. These results demonstrate the following: 1) ADAM-15 is involved in heterotypic adhesion of intraepithelial lymphocytes to IEC as well as in homotypic aggregation of T cells; 2) both the RGD motif and the cytoplasmic tail of ADAM-15 are involved for these cell-cell interactions; and 3) ADAM-15-mediated cell-cell interactions are involved in mechanisms of epithelial restitution and production of pro-inflammatory mediators. Altogether these findings point to ADAM-15 as a possible therapeutic target for prevention of inappropriate T cell activation involved in some pathologies. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
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131. Infectious etiopathogenesis of Crohn's disease.
- Author
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Carrière J, Darfeuille-Michaud A, and Nguyen HT
- Subjects
- Anti-Bacterial Agents therapeutic use, Bacteria drug effects, Bacteria immunology, Crohn Disease diagnosis, Crohn Disease genetics, Crohn Disease immunology, Crohn Disease therapy, Dysbiosis, Host-Pathogen Interactions, Humans, Intestines immunology, Microbiota, Probiotics therapeutic use, Risk Factors, Treatment Outcome, Bacteria growth & development, Crohn Disease microbiology, Intestines microbiology
- Abstract
Important advances during the last decade have been made in understanding the complex etiopathogenesis of Crohn's disease (CD). While many gaps in our knowledge still exist, it has been suggested that the etiology of CD is multifactorial including genetic, environmental and infectious factors. The most widely accepted theory states that CD is caused by an aggressive immune response to infectious agents in genetically predisposed individuals. The rise of genome-wide association studies allowed the identification of loci and genetic variants in several components of host innate and adaptive immune responses to microorganisms in the gut, highlighting an implication of intestinal microbiota in CD etiology. Moreover, numerous independent studies reported a dysbiosis, i.e., a modification of intestinal microbiota composition, with an imbalance between the abundance of beneficial and harmful bacteria. Although microorganisms including viruses, yeasts, fungi and bacteria have been postulated as potential CD pathogens, based on epidemiological, clinicopathological, genetic and experimental evidence, their precise role in this disease is not clearly defined. This review summarizes the current knowledge of the infectious agents associated with an increased risk of developing CD. Therapeutic approaches to modulate the intestinal dysbiosis and to target the putative CD-associated pathogens, as well as their potential mechanisms of action are also discussed.
- Published
- 2014
- Full Text
- View/download PDF
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