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Cristina Julio-Gonzalez L, Garcia-Cañas V, Rico F, Hernandez-Hernandez O. Transglycosylation catalysed by Caco-2 membrane disaccharidases: A new approach to understand carbohydrates digestibility. Food Res Int 2023; 172:113067. [PMID: 37689856 DOI: 10.1016/j.foodres.2023.113067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/24/2023] [Accepted: 05/26/2023] [Indexed: 09/11/2023]
Abstract
Under appropriate experimental conditions, some glycoside hydrolases can catalyze transglycosylation reactions; a hypothesis associated with this is that the glycosidic linkages formed will be preferentially hydrolyzed under optimal conditions. Therefore, the hydrolytic and transglycosylation activities of isolated membranes from differentiated Caco-2 cells on sucrose, maltose and isomaltulose were evaluated. After the enzymatic reactions, the di- and trisaccharides obtained were identified by gas chromatography coupled to a mass spectrometer. Differentiated Caco-2 cell membranes exerted hydrolytic and transglycosylation activities towards the studied disaccharides. The obtained di- and trisaccharides were detected for the first time using human cell models. Due to the absence of maltase-glucoamylase complex (MGAM) in Caco-2 cells, and the known hydrolytic activity of sucrase-isomaltase (SI) towards sucrose, maltose and isomaltulose, it is plausible that the glycosidic linkages obtained after the transglycosylation reaction, mainly α-glucosyl-fructoses and α-glucosyl-glucoses, were carried out by SI complex. This approach can be used as a model to explain carbohydrate digestibility in the small intestine and as a tool to design new oligosaccharides with low intestinal digestibility.
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Affiliation(s)
- Lesbia Cristina Julio-Gonzalez
- Institute of Food Science Research, CIAL (CSIC-UAM), Madrid-28049, Spain; Faculty of Engineering, Universidad de Cartagena, Cartagena de Indias, Colombia
| | | | - Fabian Rico
- Faculty of Engineering, Universidad de Cartagena, Cartagena de Indias, Colombia
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2
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Masloh S, Culot M, Gosselet F, Chevrel A, Scapozza L, Zeisser Labouebe M. Challenges and Opportunities in the Oral Delivery of Recombinant Biologics. Pharmaceutics 2023; 15:pharmaceutics15051415. [PMID: 37242657 DOI: 10.3390/pharmaceutics15051415] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/22/2023] [Accepted: 04/24/2023] [Indexed: 05/28/2023] Open
Abstract
Recombinant biological molecules are at the cutting-edge of biomedical research thanks to the significant progress made in biotechnology and a better understanding of subcellular processes implicated in several diseases. Given their ability to induce a potent response, these molecules are becoming the drugs of choice for multiple pathologies. However, unlike conventional drugs which are mostly ingested, the majority of biologics are currently administered parenterally. Therefore, to improve their limited bioavailability when delivered orally, the scientific community has devoted tremendous efforts to develop accurate cell- and tissue-based models that allow for the determination of their capacity to cross the intestinal mucosa. Furthermore, several promising approaches have been imagined to enhance the intestinal permeability and stability of recombinant biological molecules. This review summarizes the main physiological barriers to the oral delivery of biologics. Several preclinical in vitro and ex vivo models currently used to assess permeability are also presented. Finally, the multiple strategies explored to address the challenges of administering biotherapeutics orally are described.
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Affiliation(s)
- Solene Masloh
- Laboratoire de la Barrière Hémato-Encéphalique (LBHE), Faculté des sciences Jean Perrin, University of Artois, UR 2465, Rue Jean Souvraz, 62300 Lens, France
- Affilogic, 24 Rue de la Rainière, 44300 Nantes, France
- School of Pharmaceutical Sciences, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
| | - Maxime Culot
- Laboratoire de la Barrière Hémato-Encéphalique (LBHE), Faculté des sciences Jean Perrin, University of Artois, UR 2465, Rue Jean Souvraz, 62300 Lens, France
| | - Fabien Gosselet
- Laboratoire de la Barrière Hémato-Encéphalique (LBHE), Faculté des sciences Jean Perrin, University of Artois, UR 2465, Rue Jean Souvraz, 62300 Lens, France
| | - Anne Chevrel
- Affilogic, 24 Rue de la Rainière, 44300 Nantes, France
| | - Leonardo Scapozza
- School of Pharmaceutical Sciences, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
| | - Magali Zeisser Labouebe
- School of Pharmaceutical Sciences, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, 1 Rue Michel Servet, 1201 Geneva, Switzerland
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3
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Barber E, Houghton MJ, Williamson G. Flavonoids as Human Intestinal α-Glucosidase Inhibitors. Foods 2021; 10:foods10081939. [PMID: 34441720 PMCID: PMC8392382 DOI: 10.3390/foods10081939] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022] Open
Abstract
Certain flavonoids can influence glucose metabolism by inhibiting enzymes involved in carbohydrate digestion and suppressing intestinal glucose absorption. In this study, four structurally-related flavonols (quercetin, kaempferol, quercetagetin and galangin) were evaluated individually for their ability to inhibit human α-glucosidases (sucrase, maltase and isomaltase), and were compared with the antidiabetic drug acarbose and the flavan-3-ol(−)-epigallocatechin-3-gallate (EGCG). Cell-free extracts from human intestinal Caco-2/TC7 cells were used as the enzyme source and products were quantified chromatographically with high accuracy, precision and sensitivity. Acarbose inhibited sucrase, maltase and isomaltase with IC50 values of 1.65, 13.9 and 39.1 µM, respectively. A similar inhibition pattern, but with comparatively higher values, was observed with EGCG. Of the flavonols, quercetagetin was the strongest inhibitor of α-glucosidases, with inhibition constants approaching those of acarbose, followed by galangin and kaempferol, while the weakest were quercetin and EGCG. The varied inhibitory effects of flavonols against human α-glucosidases depend on their structures, the enzyme source and substrates employed. The flavonols were more effective than EGCG, but less so than acarbose, and so may be useful in regulating sugar digestion and postprandial glycaemia without the side effects associated with acarbose treatment.
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Wongon M, Limpeanchob N. Artocarpus lacucha Extract and Oxyresveratrol Inhibit Glucose Transporters in Human Intestinal Caco-2 Cells. PLANTA MEDICA 2021; 87:709-715. [PMID: 33511623 DOI: 10.1055/a-1324-3570] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Reduction of intestinal glucose absorption might result from either delayed carbohydrate digestion or blockage of glucose transporters. Previously, oxyresveratrol was shown to inhibit α-glucosidase, but its effect on glucose transporters has not been explored. The present study aimed to assess oxyresveratrol-induced inhibition of the facilitative glucose transporter 2 and the active sodium-dependent glucose transporter 1. An aqueous extract of Artocarpus lacucha, Puag Haad, which is oxyresveratrol-enriched, was also investigated. Glucose transport was measured by uptake into Caco-2 cells through either glucose transporter 2 or sodium-dependent glucose transporter 1 according to the culture conditions. Oxyresveratrol (40 to 800 µM) dose-dependently reduced glucose transport, which appeared to inhibit both glucose transporter 2 and sodium-dependent glucose transporter 1. Puag Haad at similar concentrations also inhibited these transporters but with greater efficacy. Oxyresveratrol and Puag Haad could help reduce postprandial hyperglycemic peaks, which are considered to be most damaging in diabetics.
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Affiliation(s)
- Matusorn Wongon
- Department of Pharmacy Practice and Center of Excellence for Innovation in Chemistry, Pharmacological Research Unit, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
| | - Nanteetip Limpeanchob
- Department of Pharmacy Practice and Center of Excellence for Innovation in Chemistry, Pharmacological Research Unit, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
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Lactose-Gated Mesoporous Silica Particles for Intestinal Controlled Delivery of Essential Oil Components: An In Vitro and In Vivo Study. Pharmaceutics 2021; 13:pharmaceutics13070982. [PMID: 34209675 PMCID: PMC8309014 DOI: 10.3390/pharmaceutics13070982] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 11/21/2022] Open
Abstract
Mesoporous silica microparticles functionalized with lactose for the specific release of essential oil components (EOCs) in the small intestine are presented. In vitro and in vivo intestinal models were applied to validate the microparticles (M41-EOC-L), in which the presence of lactase acts as the triggering stimulus for the controlled release of EOCs. Among the different microdevices prepared (containing thymol, eugenol and cinnamaldehyde), the one loaded with cinnamaldehyde showed the most significant Caco-2 cell viability reduction. On the other hand, interaction of the particles with enterocyte-like monolayers showed a reduction of EOCs permeability when protected into the designed microdevices. Then, a microdevice loaded with cinnamaldehyde was applied in the in vivo model of Wistar rat. The results showed a reduction in cinnamaldehyde plasma levels and an increase in its concentration in the lumen of the gastrointestinal tract (GIT). The absence of payload release in the stomach, the progressive release throughout the intestine and the prolonged stay of the payload in the GIT-lumen increased the bioavailability of the encapsulated compound at the site of the desired action. These innovative results, based on the specific intestinal controlled delivery, suggest that the M41-payload-L could be a potential hybrid microdevice for the protection and administration of bioactive molecules in the small intestine and colon.
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Glucose absorption regulation and mechanism of the compounds in Lilium lancifolium Thunb on Caco-2 cells. Food Chem Toxicol 2021; 149:112010. [PMID: 33493636 DOI: 10.1016/j.fct.2021.112010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/11/2021] [Accepted: 01/16/2021] [Indexed: 11/22/2022]
Abstract
In this paper, the Caco-2 cell was used to study the glucose absorption regulation and mechanism of kaempferol, caffeic acid and quercetin-3-O-β-D-galactoside in Lilium lancifolium Thunb in vitro. Glucose oxidase-peroxidase (GOD-POD) method was used to measure glucose consumption in supernatant. The fluorescent D-glucose analog (2-NBDG) was used as a tracer probe to study the changes in the fluorescence intensity of 2-NBDG uptake by Caco-2 cells with an inverted fluorescence microscope. Western blotting and quantitative real-time PCR were used to detect the protein expression and mRNA transcription of SGLT1 and GLUT2. The results showed that caffeic acid and quercetin-3-O-β-D-galactoside could significantly promote the absorption of glucose by normal Caco-2 cells compared with the control group (P < 0.001). Both caffeic acid and quercetin-3-O-β-D-galactoside could significantly promote the uptake of glucose tracer 2-NBDG on Caco-2 cells. Caffeic acid and quercetin-3-O-β-D-galactoside could significantly promote SGLT1 and GLUT2 protein expression levels and mRNA transcription (P < 0.001, P < 0.01, P < 0.05). The mechanism might be related to the promotion of SGLT1 and GLUT2 protein expression levels and mRNA transcription.
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Gene Expression Changes Accompanying the Duodenal Adenoma-Carcinoma Sequence in Familial Adenomatous Polyposis. Clin Transl Gastroenterol 2020; 10:e00053. [PMID: 31211760 PMCID: PMC6613862 DOI: 10.14309/ctg.0000000000000053] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Duodenal cancer in familial adenomatous polyposis (FAP) arises from adenomas. Differentially expressed genes (DEGs) in the duodenal adenoma-carcinoma pathway have been identified in murine FAP models, but similar data in patients with FAP are limited. Identifying such changes may have significance in understanding duodenal polyposis therapies and identifying cancer biomarkers. We performed a genome-wide transcriptional analysis to describe the duodenal adenoma-carcinoma sequence and determine changes distinguishing patients with FAP with and without duodenal cancer.
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Inhibitory effect of Artocarpus lakoocha Roxb and oxyresveratrol on α-glucosidase and sugar digestion in Caco-2 cells. Heliyon 2020; 6:e03458. [PMID: 32154416 PMCID: PMC7056649 DOI: 10.1016/j.heliyon.2020.e03458] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 12/09/2019] [Accepted: 02/18/2020] [Indexed: 12/13/2022] Open
Abstract
Long-term diabetic complications are exacerbated by post-prandial hyperglycemia which could be ameliorated by α-glucosidase inhibitor including oxyresveratrol. Puag-Haad is an aqueous extract from Artocarpus lakoocha Roxb. containing ~65% oxyresveratrol. Oxyresveratrol is an inhibitor of isolated yeast α-glucosidase enzyme but has not been tested on intact gut enterocytes where the enzyme is membrane-bound. Accordingly, differentiated Caco-2 cells that contain the native enzyme were used to test maltose hydrolysis in the present study. The results demonstrated that purified yeast α-glucosidase was non-competitively inhibited by oxyresveratrol (Ki 54.4 ± 0.7 μg/mL) and Puag-Haad (2.7 ± 0.1 μg/mL) compared to 153.8 ± 4.3 μg/mL acarbose, an anti-diabetic drug. In differentiated Caco-2 cells, both oxyresveratrol and Puag-Haad inhibited maltose hydrolysis with lesser potency compared to acarbose. Thus, although weaker than acarbose, oxyresveratrol and Puag-Haad do not inhibit pancreatic amylase which might be a therapeutic asset in preventing fermentation of unabsorbed carbohydrate causes abdominal bloating, flatulence, or diarrhea. Oxyresveratrol and Puag-Haad may help control postprandial hyperglycemia with low risk of gastrointestinal side effects.
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Pyner A, Chan SY, Tumova S, Kerimi A, Williamson G. Indirect Chronic Effects of an Oleuropein-Rich Olive Leaf Extract on Sucrase-Isomaltase In Vitro and In Vivo. Nutrients 2019; 11:nu11071505. [PMID: 31266155 PMCID: PMC6683085 DOI: 10.3390/nu11071505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 06/27/2019] [Accepted: 06/28/2019] [Indexed: 01/20/2023] Open
Abstract
Consumption of dietary bioactives is an avenue to enhancing the effective healthiness of diets by attenuating the glycaemic response. The intestinal brush border enzyme sucrase-isomaltase (SI) is the sole enzyme hydrolysing consumed sucrose, and we previously showed the acute effects of olive leaf extract (OLE) on sucrase activity when given together with sugars both in vitro and in vivo. Here we tested whether OLE could affect sucrase expression when pre-incubated chronically, a "priming" effect not dependent on competitive interaction with SI, in both a cell model and a human intervention. Using differentiated Caco-2/TC7 cells, long-term pre-treatment with oleuropein-rich olive leaf extract (OLE) lowered SI mRNA, surface protein and activity, and attenuated subsequent sucrose hydrolysis. Based on these results, a randomised, double-blinded, placebo-controlled, crossover pilot study was conducted. OLE (50 mg oleuropein) was consumed in capsule form 3 times a day for 1 week by 11 healthy young women followed by an oral sucrose tolerance test in the absence of OLE. However this treatment, compared to placebo, did not induce a change in post-prandial blood glucose maximum concentration (Glcmax), time to reach Glcmax and incremental area under the curve. These results indicate that changes in SI mRNA, protein and activity in an intestinal cell model by OLE are not sufficient under these conditions to induce a functional effect in vivo in healthy volunteers.
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Affiliation(s)
- Alison Pyner
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
| | - Shuk Yan Chan
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
| | - Sarka Tumova
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
| | - Asimina Kerimi
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Notting Hill BASE facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia
| | - Gary Williamson
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK.
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Notting Hill BASE facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
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10
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Tunçer S, Çolakoğlu M, Ulusan S, Ertaş G, Karasu Ç, Banerjee S. Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium. Heliyon 2019; 5:e01336. [PMID: 30963117 PMCID: PMC6434063 DOI: 10.1016/j.heliyon.2019.e01336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/04/2019] [Accepted: 03/07/2019] [Indexed: 01/02/2023] Open
Abstract
Colloidal platinum (Pt) is widely consumed due to its health promoting benefits. However, the exact biological effects of these nanoparticles have not been studied in detail, particularly in the gut. In the present study we observed that colloidal Pt was not cytotoxic towards three different epithelial colon cancer cell lines. Co-treatment of the colon cancer cell line Caco-2 with the oxidative stress inducing agent hydrogen peroxide (H2O2) and colloidal Pt resulted in a significant decrease in H2O2 induced oxidative stress. Colloidal Pt by itself did not induce any oxidative stress. Additionally, both overnight pretreatment of Caco-2 cells with colloidal Pt followed by 1 h treatment with H2O2, or co-treatment of cells for 1 h with colloidal Pt and H2O2 resulted in a significant recovery of cell death. Of note, the same protective effects of colloidal Pt were not observed when the oxidative stress was induced in the presence of 2, 2-azobis (2-amidinopropane) dihydrochloride, indicating that the source of free radicals may define the outcome of anti-oxidant activity of colloidal Pt. Colloidal Pt was also able to cross a model intestinal barrier formed in vitro with differentiated Caco-2 cells easily. Overall, our data indicate that colloidal Pt was not toxic towards intestinal epithelial cells, reduced H2O2 induced oxidative stress, protected from oxidative stress related death of intestinal epithelial cells and could pass a model gut barrier easily. Colloidal Pt can therefore be consumed orally for its anti-oxidant and other health promoting benefits.
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Affiliation(s)
- Sinem Tunçer
- Department of Biological Sciences, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara 06800, Turkey
| | - Melis Çolakoğlu
- Department of Biological Sciences, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara 06800, Turkey
| | - Sinem Ulusan
- Department of Chemistry, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara 06800, Turkey
| | - Gülay Ertaş
- Department of Chemistry, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara 06800, Turkey
| | - Çimen Karasu
- Department of Medical Pharmacology, Gazi University, Faculty of Medicine, Ankara 06500, Turkey
| | - Sreeparna Banerjee
- Department of Biological Sciences and Cancer Systems Biology Laboratory (CanSyl), Orta Dogu Teknik Universitesi (ODTU/METU), Ankara 06800, Turkey
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Tunçer S, Banerjee S. Determination of Autophagy in the Caco-2 Spontaneously Differentiating Model of Intestinal Epithelial Cells. Methods Mol Biol 2019; 1854:55-70. [PMID: 28842896 DOI: 10.1007/7651_2017_66] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The Caco-2 colorectal cancer cell line is widely used as a model for intestinal differentiation and barrier function. These cells, upon reaching confluency, spontaneously differentiate into enterocyte-like cells, synthesize intestinal enzymes, and form domes. Caco-2 cells also undergo autophagy in the course of differentiation. The criteria to establish the induction of autophagy in cells are already well established. Here, we describe the protocol for the spontaneous differentiation of Caco-2 cells and the detection of autophagy using Western blot, flow cytometry, and immunofluorescence.
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Affiliation(s)
- Sinem Tunçer
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
| | - Sreeparna Banerjee
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
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12
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Igarashi M, Watanabe K, Tsuduki T, Kimura I, Kubota N. NAPE-PLD controls OEA synthesis and fat absorption by regulating lipoprotein synthesis in an in vitro model of intestinal epithelial cells. FASEB J 2018; 33:3167-3179. [PMID: 30399323 DOI: 10.1096/fj.201801408r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Oleoylethanolamide (OEA), a fatty acid ethanolamide (FAE), is a lipid mediator that controls food intake and lipid metabolism. Accumulating data imply the importance of intestinal OEA in controlling satiety in addition to gastrointestinal peptide hormones. Although the biochemical pathway of FAE production has been illustrated, the enzymes responsible for the cleavage of OEA from its precursor N-acyl-phosphatidylethanolamine (NAPE) must be identified among reported candidates in the gut. In this study, we assessed the involvement of NAPE-specific phospholipase D (NAPE-PLD), which can directly release FAEs from NAPE, in intestinal OEA synthesis and lipid metabolism. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPER-associated protein 9 (Cas9)-mediated deletion of the NAPE-PLD gene in intestinal epithelial-like Caco-2 cells reduced OEA levels, regardless of their differentiation states. Transcriptome analysis revealed that deletion of NAPE-PLD activates a transcriptional program for nutrient transportation, including lipids and lipoproteins, and inactivates cell-cycle or mitosis-related genes in Caco-2 cells. In addition, the basolateral secretion of lipoproteins was increased in NAPE-PLD-deleted cells although lipoprotein size was not affected. By contrast, cellular lipid levels were reduced in NAPE-PLD-deleted cells. Overall, these results indicate that NAPE-PLD plays important roles in OEA synthesis and fat absorption by regulating lipoprotein production in the intestinal epithelial cells.-Igarashi, M., Watanabe, K., Tsuduki, T., Kimura, I., Kubota, N. NAPE-PLD controls OEA synthesis and fat absorption by regulating lipoprotein synthesis in an in vitro model of intestinal epithelial cells.
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Affiliation(s)
- Miki Igarashi
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.,RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | | | - Tsuyoshi Tsuduki
- Department of Bioscience and Biotechnology for Future Bioindustries, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Ikuo Kimura
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Naoto Kubota
- RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan.,Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Department of Clinical Nutrition, National Institute of Health and Nutrition, Tokyo, Japan; and.,Department of Clinical Nutrition Therapy, The University of Tokyo, Tokyo, Japan
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Dosh RH, Jordan-Mahy N, Sammon C, Le Maitre CL. Tissue Engineering Laboratory Models of the Small Intestine. TISSUE ENGINEERING PART B-REVIEWS 2018; 24:98-111. [DOI: 10.1089/ten.teb.2017.0276] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Rasha Hatem Dosh
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
- Department of Anatomy and Histology, Faculty of Medicine, University of Kufa, Kufa, Iraq
| | - Nicola Jordan-Mahy
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
| | - Christopher Sammon
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, United Kingdom
| | - Christine Lyn Le Maitre
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
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14
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Chegeni M, Amiri M, Nichols BL, Nairn HY, Hamaker BR. Dietary starch breakdown product sensing mobilizes and apically activates α‐glucosidases in small intestinal enterocytes. FASEB J 2018; 32:3903-3911. [DOI: 10.1096/fj.201701029r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mohammad Chegeni
- Department of Food ScienceWhistler Center for Carbohydrate ResearchPurdue UniversityWest LafayetteIndianaUSA
| | - Mahdi Amiri
- Department of Physiological ChemistryUniversity of Veterinary Medicine HannoverHannoverGermany
- Department of Gastroenterology, Hepatology, and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Buford L. Nichols
- Department of PediatricsU.S. Department of Agriculture/Agricultural Research ServiceChildren's Nutrition Research CenterBaylor College of MedicineHoustonTexasUSA
| | - Hassan Y. Nairn
- Department of Physiological ChemistryUniversity of Veterinary Medicine HannoverHannoverGermany
| | - Bruce R. Hamaker
- Department of Food ScienceWhistler Center for Carbohydrate ResearchPurdue UniversityWest LafayetteIndianaUSA
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15
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Peck BCE, Sincavage J, Feinstein S, Mah AT, Simmons JG, Lund PK, Sethupathy P. miR-30 Family Controls Proliferation and Differentiation of Intestinal Epithelial Cell Models by Directing a Broad Gene Expression Program That Includes SOX9 and the Ubiquitin Ligase Pathway. J Biol Chem 2016; 291:15975-84. [PMID: 27261459 PMCID: PMC4965549 DOI: 10.1074/jbc.m116.733733] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Indexed: 12/18/2022] Open
Abstract
Proliferation and differentiation of intestinal epithelial cells (IECs) occur in part through precise regulation of key transcription factors, such as SOX9. MicroRNAs (miRNAs) have emerged as prominent fine-tuners of transcription factor expression and activity. We hypothesized that miRNAs, in part through the regulation of SOX9, may mediate IEC homeostasis. Bioinformatic analyses of the SOX9 3'-UTR revealed highly conserved target sites for nine different miRNAs. Of these, only the miR-30 family members were both robustly and variably expressed across functionally distinct cell types of the murine jejunal epithelium. Inhibition of miR-30 using complementary locked nucleic acids (LNA30bcd) in both human IECs and human colorectal adenocarcinoma-derived Caco-2 cells resulted in significant up-regulation of SOX9 mRNA but, interestingly, significant down-regulation of SOX9 protein. To gain mechanistic insight into this non-intuitive finding, we performed RNA sequencing on LNA30bcd-treated human IECs and found 2440 significantly increased genes and 2651 significantly decreased genes across three time points. The up-regulated genes are highly enriched for both predicted miR-30 targets, as well as genes in the ubiquitin-proteasome pathway. Chemical suppression of the proteasome rescued the effect of LNA30bcd on SOX9 protein levels, indicating that the regulation of SOX9 protein by miR-30 is largely indirect through the proteasome pathway. Inhibition of the miR-30 family led to significantly reduced IEC proliferation and a dramatic increase in markers of enterocyte differentiation. This in-depth analysis of a complex miRNA regulatory program in intestinal epithelial cell models provides novel evidence that the miR-30 family likely plays an important role in IEC homeostasis.
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Affiliation(s)
| | | | | | | | | | - P Kay Lund
- From the Curriculum in Genetics & Molecular Biology, Cell Biology and Physiology, and
| | - Praveen Sethupathy
- From the Curriculum in Genetics & Molecular Biology, the Departments of Genetics, the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
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16
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Chaudet MM, Rose DR. Divergent evolution for diverse substrate recognition by family 31 glycoside hydrolases. Biochem Cell Biol 2016; 94:323-30. [PMID: 27459002 DOI: 10.1139/bcb-2016-0022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Carbohydrates make up an important component of our diet, contributing a significant portion to our total caloric intake. The ability to harvest these molecules for energy is reliant on the activity of carbohydrate-active enzymes. Family 31 α-glucosidases are a group of glycoside hydrolases that has been shown to play a key role in the metabolic process of hydrolyzing dietary starch into monomers of glucose. The purpose of the research presented here is to explore evolutionary changes that occurred within this family of glycoside hydrolases, and to relate these divergences to observed structural differences in relation to predicted substrate preferences. Here we report specific single amino acid changes that are believed to have arisen through evolution, and are directly related to the ability of these enzymes to bind different starch-based glycans. Through phylogenetic analysis we observed a number of evolutionary adaptions that we believe resulted in duplicated genes that allow for the efficient utilization of dietary starch.
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Affiliation(s)
- M M Chaudet
- University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada.,University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - D R Rose
- University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada.,University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
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17
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Kim HJ, Ingber DE. Gut-on-a-Chip microenvironment induces human intestinal cells to undergo villus differentiation. Integr Biol (Camb) 2014; 5:1130-40. [PMID: 23817533 DOI: 10.1039/c3ib40126j] [Citation(s) in RCA: 467] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Existing in vitro models of human intestinal function commonly rely on use of established epithelial cell lines, such as Caco-2 cells, which form polarized epithelial monolayers but fail to mimic more complex intestinal functions that are required for drug development and disease research. We show here that a microfluidic 'Gut-on-a-Chip' technology that exposes cultured cells to physiological peristalsis-like motions and liquid flow can be used to induce human Caco-2 cells to spontaneously undergo robust morphogenesis of three-dimensional (3D) intestinal villi. The cells of that line these villus structures are linked by tight junctions, and covered by brush borders and mucus. They also reconstitute basal proliferative crypts that populate the villi along the crypt-villus axis, and form four different types of differentiated epithelial cells (absorptive, mucus-secretory, enteroendocrine, and Paneth) that take characteristic positions similar to those observed in living human small intestine. Formation of these intestinal villi also results in exposure of increased intestinal surface area that mimics the absorptive efficiency of human intestine, as well enhanced cytochrome P450 3A4 isoform-based drug metabolizing activity compared to conventional Caco-2 cell monolayers cultured in a static Transwell system. The ability of the human Gut-on-a-Chip to recapitulate the 3D structures, differentiated cell types, and multiple physiological functions of normal human intestinal villi may provide a powerful alternative in vitro model for studies on intestinal physiology and digestive diseases, as well as drug development.
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Affiliation(s)
- Hyun Jung Kim
- Wyss Institute for Biologically Inspired Engineering at Harvard University, CLSB Bldg. 5th floor, 3 Blackfan Circle, Boston, MA 02115, USA.
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18
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Abstract
Excessive post-prandial glucose excursions are a risk factor for developing diabetes, associated with impaired glucose tolerance. One way to limit the excursion is to inhibit the activity of digestive enzymes for glucose production and of the transporters responsible for glucose absorption. Flavonols, theaflavins, gallate esters, 5-caffeoylqunic acid and proanthocyanidins inhibit α-amylase activity. Anthocyanidins and catechin oxidation products, such as theaflavins and theasinsensins, inhibit maltase; sucrase is less strongly inhibited but anthocyanidins seem somewhat effective. Lactase is inhibited by green tea catechins. Once produced in the gut by digestion, glucose is absorbed by SGLT1 and GLUT2 transporters, inhibited by flavonols and flavonol glycosides, phlorizin and green tea catechins. These in vitro data are supported by oral glucose tolerance tests on animals, and by a limited number of human intervention studies on polyphenol-rich foods. Acarbose is a drug whose mechanism of action is only through inhibition of α-amylases and α-glucosidases, and in intervention studies gives a 6% reduction in diabetes risk over 3 years. A lifetime intake of dietary polyphenols, assuming the same mechanism, has therefore a comparable potential to reduce diabetes risk, but more in vivo studies are required to fully test the effect of modulating post-prandial blood glucose in humans.
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Affiliation(s)
- Gary Williamson
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK.
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19
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Précourt LP, Marcil V, Ntimbane T, Taha R, Lavoie JC, Delvin E, Seidman EG, Beaulieu JF, Levy E. Antioxidative properties of paraoxonase 2 in intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 2012; 303:G623-34. [PMID: 22744335 PMCID: PMC3468556 DOI: 10.1152/ajpgi.00039.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Paraoxonase (PON) family members seem central to a wide variety of human illnesses, but appreciation of their antioxidative function in the gastrointestinal tract is in its infancy. The major objective of the present work is to highlight the role of the ubiquitously expressed PON2 in the small intestine. With use of pLKO lentiviral vector containing short hairpin RNA (shRNA) lentivirus, PON2 expression was knocked down in intestinal Caco-2/15 cells, where antioxidative status, lipid peroxidation, and degree of inflammation were evaluated. As a consequence of PON2 inactivation in the epithelial cells, we observed 1) imbalanced primary and secondary antioxidative responses, characterized by increased superoxide dismutases and decreased catalase, 2) high concentrations of H(2)O(2) and malondialdehyde, along with low glutathione-to-glutathione disulfide ratio, 3) upregulation of TNF-α, IL-6, and monocyte chemoattractant protein-1 gene expression after induction of oxidative stress, and 4) raised level of the activation of transcription factor NF-κB, which was likely implicated in exacerbation of the inflammatory activation. These results suggest that PON2 is involved in the antioxidative and anti-inflammatory response in intestinal epithelial cells.
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Affiliation(s)
- Louis-Philippe Précourt
- 1Department of Nutrition, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada;
| | - Valérie Marcil
- 2Research Institute, McGill University, Montreal, Quebec, Canada;
| | - Thierry Ntimbane
- 1Department of Nutrition, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada;
| | - Rame Taha
- 1Department of Nutrition, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada;
| | | | - Edgard Delvin
- 3Department of Pediatrics, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; ,4Department of Biochemistry, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; and
| | - Ernest G. Seidman
- 2Research Institute, McGill University, Montreal, Quebec, Canada; ,5Canadian Institutes for Health Research Team on the Digestive Epithelium, Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jean-François Beaulieu
- 5Canadian Institutes for Health Research Team on the Digestive Epithelium, Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Emile Levy
- 1Department of Nutrition, Research Centre, CHU-Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; ,5Canadian Institutes for Health Research Team on the Digestive Epithelium, Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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20
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A protocol for in situ enzyme assays to assess the differentiation of human intestinal Caco-2 cells. Toxicol In Vitro 2011; 26:1247-51. [PMID: 22123491 DOI: 10.1016/j.tiv.2011.11.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 09/15/2011] [Accepted: 11/09/2011] [Indexed: 11/24/2022]
Abstract
The Caco-2 cell line spontaneously differentiates into polarised enterocytes expressing high levels of brush border enzymes typical of small intestinal epithelial cells (peptidases, alkaline phosphatase, disaccharidases). The activities of these enzymes gradually increase after cell confluence reaching a plateau after 2-3 weeks of culture and can be used as reliable markers to evaluate differentiation of Caco-2 cells. We have developed a rapid in situ method on live cells to measure activities of alkaline phosphatase, alanyl amino peptidase and sucrase. The substrates were added to the apical compartment of confluent cells maintained for 8, 15 and 21 days on polycarbonate filter inserts and sampling was performed at time intervals. Alkaline phosphatase and alanyl aminopeptidase were assayed using as substrates p-Nitrophenyl phosphate and alanine-p-nitroanilide, respectively, and the yellow product detected spectrophotometrically at 405 nm. Sucrase activity was measured as the release of glucose from sucrose using a fluorimetric assay (Amplex® Red Glucose Assay Kit) in which H(2)O(2), produced by the coupled glucose oxidase/horseradish peroxidase reactions, oxidises the colourless reagent to red-fluorescent resorufin. All these assays are rapid and reproducible and can easily be adapted to robotised high throughput platforms.
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21
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Brodrick B, Vidrich A, Porter E, Bradley L, Buzan JM, Cohn SM. Fibroblast growth factor receptor-3 (FGFR-3) regulates expression of paneth cell lineage-specific genes in intestinal epithelial cells through both TCF4/beta-catenin-dependent and -independent signaling pathways. J Biol Chem 2011; 286:18515-25. [PMID: 21388956 DOI: 10.1074/jbc.m111.229252] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Fibroblast growth factor receptor-3 (FGFR-3) expression in the developing intestine is restricted to the undifferentiated epithelial cells within the lower portion of the crypt. We previously showed that mice lacking functional FGFR-3 have a significant decrease in the number of Paneth cells in the small intestine. Here, we used Caco2 cells to investigate whether FGFR-3 signaling can directly modulate expression of Paneth cell differentiation markers through its effects on TCF4/β-catenin or through other signaling pathways downstream of this receptor. Caco2 cells treated with FGFR-3 ligands or expressing FGFR-3(K650E), a constitutively active mutant, resulted in a significantly increased expression of genes characteristic of mature Paneth cells, including human α-defensins 5 and 6 (HD5 and HD6) and Paneth cell lysozyme, whereas enterocytic differentiation markers were reduced. Activation of FGFR-3 signaling sustained high levels of β-catenin mRNA expression, leading to increased TCF4/β-catenin-regulated transcriptional activity in Caco2 cells. Sustained activity of the TCF4/β-catenin pathway was required for the induction of Paneth cell markers. Activation of the MAPK pathway by FGFR-3 is also required for the induction of Paneth cell markers in addition to and independent of the effect of FGFR-3 on TCF4/β-catenin activity. These studies suggest that coordinate activation of multiple independent signaling pathways downstream of FGFR-3 is involved in regulation of Paneth cell differentiation.
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Affiliation(s)
- Brooks Brodrick
- Division of Gastroenterology and Hepatology, University of Virginia, Charlottesville, Virginia 22908, USA
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22
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The effects of ethanol administration on brush border membrane glycolipids in rat intestine. Alcohol 2010; 44:515-22. [PMID: 20708369 DOI: 10.1016/j.alcohol.2010.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 05/17/2010] [Accepted: 07/14/2010] [Indexed: 11/22/2022]
Abstract
Ethanol ingestion is well known to induce morphological and biochemical changes in intestine and is responsible for intestinal dysfunctions. Luminal surface of enterocytes is rich in glycolipids, but the effects of ethanol ingestion on membrane glycolipids are not well characterized. In the present study, rats were given 1 mL of 30% ethanol daily for 15, 25, 35, and 56 days. Ethanol feeding for 15 days did not affect glycolipid pattern in microvillus membranes, but the levels of cerebrosides (glucosylceramide, lactosylceramide, globotriasyloceramide) were enhanced in rats fed with ethanol for 35 or 56 days compared with controls. In contrast, the content of fucolipids and gangliosides was reduced in rats on ethanol ingestion for 35 or 56 days. The observed changes in membrane glycolipids were substantiated using biotinylated lectins Jacalin (affinity for N-acetylgalactosamine) and Aleuria aurantia (affinity for α-l-fucose). The incorporation of [(14)C]-mannose and [(14)C]-glucosamine revealed an increase (P<.01) in glucosamination and reduction (P<.01) in mannosylation of glycolipids from ethanol-fed rats for 45 days compared with controls. These findings were further characterized by autoradiography of the glycolipids separated on thin layer chromatograms. These findings indicate that ethanol ingestion modulates the glycolipids composition of brush borders, resulting in generalized aberration of intestinal glycosylation in chronic alcoholism in rats.
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23
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Receptor-Mediated Transcytosis of Leptin through Human Intestinal Cells In Vitro. Int J Cell Biol 2010; 2010:928169. [PMID: 20454702 PMCID: PMC2862316 DOI: 10.1155/2010/928169] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 02/11/2010] [Indexed: 01/08/2023] Open
Abstract
Gastric Leptin is absorbed by duodenal enterocytes and released on the basolateral side towards the bloodstream. We investigated in vitro some of the mechanisms of this transport. Caco-2/15 cells internalize leptin from the apical medium and release it through transcytosis in the basal medium in a time- temperature-dependent and saturable fashion. Leptin receptors are revealed on the apical brush-border membrane of the Caco-2 cells. RNA-mediated silencing of the receptor led to decreases in the uptake and basolateral release. Leptin in the basal medium was found bound to the soluble form of its receptor. An inhibitor of clathrin-dependent endocytosis (chlorpromazine) decreased leptin uptake. Confocal immunocytochemistry and the use of brefeldin A and okadaic acid revealed the passage of leptin through the Golgi apparatus. We propose that leptin transcytosis by intestinal cells depends on its receptor, on clathrin-coated vesicles and transits through the Golgi apparatus.
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24
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Suzuki T, Mochizuki K, Goda T. Localized expression of genes related to carbohydrate and lipid absorption along the crypt-villus axis of rat jejunum. Biochim Biophys Acta Gen Subj 2009; 1790:1624-35. [PMID: 19715743 DOI: 10.1016/j.bbagen.2009.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 08/13/2009] [Accepted: 08/18/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND Enterocytes of the jejunum express several genes related to digestion/absorption of nutrients and ions when these cells rapidly differentiate from crypt to villus cells. However, it is unknown whether the distribution of extensive gene expression along the villus-crypt axis of the jejunum is altered during differentiation. METHODS We investigated the changes in jejunal gene expression during differentiation from crypt to villus cells in rats using DNA microarray analysis on cryostat sections of the villus-crypt columns. RESULTS During differentiation, the expression of many genes related to cell growth rapidly decreased, while expression of genes related to digestion and absorption of nutrients and ions increased. Expression of a subset of genes related to the digestion and absorption of starch and sucrose was highest at the middle of the villi, whereas expression of genes related to dietary fat absorption was highest at the top of the villi. Several transcriptional factors such as Pdx1, Foxa2 and Thra were expressed in the crypt, whereas Klf15 was highly expressed during the crypt-villus transition. Expression of Klf4 and Pparg was highest at the top of the villi. CONCLUSIONS Subsets of genes related to the digestion and absorption of starch/sucrose and dietary fat as well as their transcriptional factors/co-factors are expressed in the specific locations along the crypt-villus axis. GENERAL SIGNIFICANCE The jejunum may absorb nutrients effectively by simultaneously expressing subsets of genes along the villus-crypt axis.
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Affiliation(s)
- Takuji Suzuki
- Laboratory of Nutritional Physiology, The University of Shizuoka Graduate School of Nutritional and Environmental Sciences and Global COE, Shizuoka, Japan
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25
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Li T, Yang W, Li M, Byun DS, Tong C, Nasser S, Zhuang M, Arango D, Mariadason JM, Augenlicht LH. Expression of selenium-binding protein 1 characterizes intestinal cell maturation and predicts survival for patients with colorectal cancer. Mol Nutr Food Res 2009; 52:1289-99. [PMID: 18435490 DOI: 10.1002/mnfr.200700331] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To identify candidate genes involved in the development of colorectal cancer, we used cDNA microarrays to analyze gene expression differences between human colorectal tumors and paired adjacent normal mucosa. We identified approximately 3.5-fold significant downregulation of selenium-binding protein 1 (SBP1) in colorectal tumors compared to normal mucosa (p = 0.003). Importantly, stage III colorectal cancer patients with low tumor-SBP1 expression had significantly shorter disease-free and overall survival as compared with those patients with high tumor-SBP1 expression (p = 0.04 and 0.03, respectively). We further characterized the role of SBP1 in colorectal cancer in vivo and in vitro. In normal tissue, SBP1 was maximally expressed in terminally differentiated epithelial cells on the luminal surface of crypts in the large intestine. Consistent with this in vivo localization, SBP1 was upregulated during in vitro colonic cell differentiation along the absorptive (Caco-2) and secretory (HT29 Clones 16E and 19A) cell lineages. Downregulation (approximately 50%) of SBP1 expression by small interfering RNA in colonic cancer cells was associated with reduced expression of another epithelial differentiation marker, carcinoembryonic antigen (CEA), although PCNA and p21(WAF1/cip1 )expression were not altered. These data demonstrate that higher expression of SBP1 is associated with differentiation of the normal colonic epithelia and may be a positive prognostic factor for survival in stage III colorectal carcinoma.
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Affiliation(s)
- Tianhong Li
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, USA.
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26
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Linder N, Martelin E, Lundin M, Louhimo J, Nordling S, Haglund C, Lundin J. Xanthine oxidoreductase - clinical significance in colorectal cancer and in vitro expression of the protein in human colon cancer cells. Eur J Cancer 2008; 45:648-55. [PMID: 19112016 DOI: 10.1016/j.ejca.2008.10.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 10/02/2008] [Accepted: 10/15/2008] [Indexed: 11/27/2022]
Abstract
Xanthine oxidoreductase (XOR) is a key enzyme in degradation of DNA and RNA, and has previously been shown to be decreased in aggressive breast and gastric cancer. In this study, XOR expression was assessed in tissue microarray specimens of 478 patients with colorectal cancer and related to clinical parameters. In addition, we performed in vitro studies of XOR activity, protein and mRNA in colon cancer cells (Caco-2). Results from the tissue expression analyses show that XOR was decreased in 62% and undetectable in 22% of the tumours as compared to normal tissue. Loss of XOR was associated with poor grade of differentiation (p=0.006) and advanced Dukes stage (p=0.03). In multivariate survival analysis, XOR was a prognostic factor (p=0.008), independent of Dukes stage, histological grade, age and tumour location. The in vitro analyses show that XOR is not measurable in undifferentiated Caco-2 cells, but appears and increases with differentiation. We conclude that XOR expression is associated with histological grade of differentiation and extent of disease in colorectal cancer, and it provides significant prognostic information independently of established factors.
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Affiliation(s)
- Nina Linder
- Department of Oncology, Institute of Clinical Medicine, University of Helsinki, Haartmaninkatu 4, PO Box 105, 00029 Helsinki, Finland
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27
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Lukovac S, Los EL, Stellaard F, Rings EHHM, Verkade HJ. Essential fatty acid deficiency in mice impairs lactose digestion. Am J Physiol Gastrointest Liver Physiol 2008; 295:G605-13. [PMID: 18653724 DOI: 10.1152/ajpgi.90206.2008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Essential fatty acid (EFA) deficiency in mice induces fat malabsorption. We previously reported indications that the underlying mechanism is located at the level of the intestinal mucosa. We have investigated the effects of EFA deficiency on small intestinal morphology and function. Mice were fed an EFA-deficient or control diet for 8 wk. A 72-h fat balance, the EFA status, and small intestinal histology were determined. Carbohydrate absorptive and digestive capacities were assessed by stable isotope methodology after administration of [U-(13)C]glucose and [1-(13)C]lactose. The mRNA expression and enzyme activity of lactase, and concentrations of the EFA linoleic acid (LA) were measured in small intestinal mucosa. Mice fed the EFA-deficient diet were markedly EFA-deficient with a profound fat malabsorption. EFA deficiency did not affect the histology or proliferative capacity of the small intestine. Blood [13C6]glucose appearance and disappearance were similar in both groups, indicating unaffected monosaccharide absorption. In contrast, blood appearance of [13C]glucose, originating from [1-(13)C]lactose, was delayed in EFA-deficient mice. EFA deficiency profoundly reduced lactase activity (-58%, P<0.01) and mRNA expression (-55%, P<0.01) in mid-small intestine. Both lactase activity and its mRNA expression strongly correlated with mucosal LA concentrations (r=0.77 and 0.79, respectively, P<0.01). EFA deficiency in mice inhibits the capacity to digest lactose but does not affect small intestinal histology. These data underscore the observation that EFA deficiency functionally impairs the small intestine, which in part may be mediated by low LA levels in the enterocytes.
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Affiliation(s)
- S Lukovac
- Pediatric Gastroenterology, Department of Pediatrics, Beatrix Children's Hospital, Groningen University Institute for Drug Exploration, Center for Liver, Digestive and Metabolic Diseases, Groningen, The Netherlands
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28
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Graham WV, Wang F, Clayburgh DR, Cheng JX, Yoon B, Wang Y, Lin A, Turner JR. Tumor Necrosis Factor-induced Long Myosin Light Chain Kinase Transcription Is Regulated by Differentiation-dependent Signaling Events. J Biol Chem 2006; 281:26205-15. [PMID: 16835238 DOI: 10.1074/jbc.m602164200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Myosin light chain kinase (MLCK) is expressed as long and short isoforms from unique transcriptional start sites within a single gene. Tumor necrosis factor (TNF) augments intestinal epithelial long MLCK expression, which is critical to cytoskeletal regulation. We found that TNF increases long MLCK mRNA transcription, both in human enterocytes in vitro and murine enterocytes in vivo.5'-RACE identified two novel exons, 1A and 1B, which encode alternative long MLCK transcriptional start sites. Chromatin immunoprecipitation (ChIP) and site-directed mutagenesis identified two essential Sp1 sites upstream of the exon 1A long MLCK transcriptional start site. Analysis of deletion and truncation mutants showed that a 102-bp region including these Sp1 sites was necessary for basal transcription. A promoter construct including 4-kb upstream of exon 1A was responsive to TNF, AP-1, or NFkappaB, but all except NFkappaB responses were absent in a shorter 2-kb construct, and all responses were absent in a 1-kb construct. Electrophoretic mobility shift assays, ChIP, and site-directed mutagenesis explained these data by identifying three functional AP-1 sites between 2- and 4-kb upstream of exon 1A and two NFkappaB sites between 1- and 2-kb upstream of exon 1A. Analysis of differentiating epithelia showed that only well differentiated enterocytes activated the 4-kb long MLCK promoter in response to TNF, and consensus promoter reporters demonstrated that TNF-induced NFkappaB activation decreased during differentiation while TNF-induced AP-1 activation increased. Thus either AP-1 or NFkappaB can up-regulate long MLCK transcription, but the mechanisms by which TNF up-regulates intestinal epithelial long MLCK transcription from exon 1A are differentiation-dependent.
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Affiliation(s)
- W Vallen Graham
- Department of Pathology, University of Chicago, Chicago, Illinois 60637, USA
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29
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Godiwala NT, Vandewalle A, Ward HD, Leav BA. Quantification of in vitro and in vivo Cryptosporidium parvum infection by using real-time PCR. Appl Environ Microbiol 2006; 72:4484-8. [PMID: 16751574 PMCID: PMC1489663 DOI: 10.1128/aem.00189-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 04/09/2006] [Indexed: 11/20/2022] Open
Abstract
Established methods for quantifying experimental Cryptosporidium infection are highly variable and subjective. We describe a new technique using quantitative real-time PCR (qPCR) that can be used to measure in vitro and in vivo laboratory infections with Cryptosporidium. We show for the first time that qPCR permits absolute quantification of the parasite while simultaneously controlling for the amount of host tissue and correlates significantly with established methods of quantification in in vitro and in vivo laboratory models of infection.
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Affiliation(s)
- Nihal T Godiwala
- Division of Geographic Medicine and Infectious Diseases, Tufts-New England Medical Center, Box 041, 750 Washington Street, Boston, MA 02111, USA
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Gautrey H, McConnell J, Hall J, Hesketh J. Polarised distribution of the RNA-binding protein Staufen in differentiated intestinal epithelial cells. FEBS Lett 2005; 579:2226-30. [PMID: 15811346 DOI: 10.1016/j.febslet.2005.02.074] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 01/21/2005] [Accepted: 02/08/2005] [Indexed: 11/22/2022]
Abstract
mRNA localisation, as a mechanism for directing localised protein synthesis, plays a vital role in the functioning of certain cells, such as neurons and oocytes. Potentially this mechanism may also occur in polarised intestinal epithelial cells. Here we show that Staufen1(55), a protein involved in mRNA localisation and transport, is asymmetrically distributed in differentiated Caco-2 intestinal epithelial cells and partly co-localised with calnexin, a marker of the endoplasmic reticulum. The localisation to the apical region of the cell indicates that Staufen may be involved in localisation of transcripts to this domain.
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Affiliation(s)
- Hannah Gautrey
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle-upon-Tyne NE1 7RU, UK
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31
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Troelsen JT. Adult-type hypolactasia and regulation of lactase expression. Biochim Biophys Acta Gen Subj 2005; 1723:19-32. [PMID: 15777735 DOI: 10.1016/j.bbagen.2005.02.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 02/08/2005] [Accepted: 02/09/2005] [Indexed: 11/25/2022]
Abstract
A common genetically determined polymorphism in the human population leads to two distinct phenotypes in adults, lactase persistence and adult-type hypolactasia (lactase non-persistence). All healthy newborn children express high levels of lactase and are able to digest large quantities of lactose, the main carbohydrate in milk. Individuals with adult-type hypolactasia lose their lactase expression before adulthood and consequently often become lactose intolerant with associated digestive problems (e.g. diarrhoea). In contrast, lactase persistent individuals have a lifelong lactase expression and are able to digest lactose as adults. Lactase persistence can be regarded as the mutant phenotype since other mammals down-regulate their lactase expression after weaning (the postweaning decline). This phenomenon does not occur in lactase persistent individuals. The regulation of lactase expression is mainly transcriptional and it is well established that adult-type hypolactasia is inherited in an autosomal recessive manner, whereas persistence is dominant. The recent findings of single nucleotide polymorphisms associated with lactase persistence have made it possible to study the potential mechanisms underlying adult-type hypolactasia. This work has led to the identification of gene-regulatory sequences located far from the lactase gene (LCT). The present review describes the recent advances in the understanding of the regulation of lactase expression and the possible mechanisms behind adult-type hypolactasia.
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Affiliation(s)
- Jesper T Troelsen
- Department of Medical Biochemistry and Genetics, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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32
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Verhave M, Krasinski SD, Christian SI, Van Schaik S, Van Den Brink GR, Doting EMH, Maas SM, Wolthers KC, Grand RJ, Montgomery RK. Regulatory regions in the rat lactase-phlorizin hydrolase gene that control cell-specific expression. J Pediatr Gastroenterol Nutr 2004; 39:275-85. [PMID: 15319629 DOI: 10.1097/00005176-200409000-00010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Lactase-phlorizin hydrolase (LPH) is an enterocyte-specific gene whose expression has been well-characterized, not only developmentally but also along the crypt-villus axis and along the length of the small bowel. Previous studies from the authors' laboratory have demonstrated that 2 kb of the 5'-flanking region of the rat LPH gene control the correct tissue, cell, and crypt-villus expression in transgenic animals. METHODS To examine further the regulation conferred by this region, protein-DNA interactions were studied using DNase I footprint analyses in LPH-expressing and nonexpressing cell lines. Functional delineation of this 5'-flanking sequence was performed using deletion analysis in transient transfection assays. RESULTS Studies revealed a generally positive activity between -74 and -37 bp, a cell-specific negative region between -210 and -95 bp, and additional elements further toward the 5'-terminus that conferred a highly cell-specific response in reporter activity. Computer analysis of distal regions encompassing identified footprints revealed potential binding sites for various intestinal transcription factors. Co-transfection and electromobility shift assay experiments indicated binding of HNF3beta at three sites relevant to LPH expression. CONCLUSIONS The data demonstrate that the cell specificity of LPH gene expression depends upon both positive and negative interactions among elements in the first 2 kb of the LPH 5'-flanking region.
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Affiliation(s)
- Menno Verhave
- Division of Pediatric Gastroenterology and Nutrition, Department of Pediatrics, The Floating Hospital for Children, New England Medical Center Hospitals, Boston, Massachusetts, USA
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Chen AC, Donovan SM. Genistein at a concentration present in soy infant formula inhibits Caco-2BBe cell proliferation by causing G2/M cell cycle arrest. J Nutr 2004; 134:1303-8. [PMID: 15173388 DOI: 10.1093/jn/134.6.1303] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fifteen percent of all U.S. infants are fed soy formulas containing up to 47 mg/L of isoflavones (>65% as genistin + genistein); thus, these infants' intestines are exposed to a high dose of genistein, a phytoestrogen and tyrosine kinase inhibitor. Little attention has been focused on genistein's impact on the developing intestine. We hypothesized that a high dose of genistein would inhibit intestinal cell growth. Caco-2BBe human intestinal cells were exposed to 0, 3.7, and 111 micro mol/L (0, 1, and 30 mg/L) genistein in DMEM + 0.5% fetal bovine serum for 24-48 h. Cell number, thymidine incorporation, apoptosis, and cell cycle analyses were performed. The low genistein concentration increased intestinal cell proliferation by 28% (P = 0.001), but did not affect cell number or caspase-3 activity compared to the control. Furthermore, the addition of ICI, an estrogen receptor antagonist, negated the proliferative effect of the low genistein. In contrast, the high genistein concentration reduced cell number by 40%, proliferation by 94%, and caspase-3 activity by 50% compared to the control (P < 0.05). Cell cycle analysis after 48 h exposure to high genistein revealed 37% of cells in G0/G1 and 35% in G2/M vs. 71% in G0/G1 and 17% in G2/M for the control and low genistein groups. Thus, a biphasic effect of genistein was seen with a low dose stimulating intestinal cell proliferation through the estrogen receptor, whereas a high dose of genistein inhibited intestinal cell proliferation and altered cell cycle dynamics. A high dose of genistein may potentially compromise intestinal growth.
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Affiliation(s)
- An-Chian Chen
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Labadie K, Pelletier I, Saulnier A, Martin J, Colbère-Garapin F. Poliovirus mutants excreted by a chronically infected hypogammaglobulinemic patient establish persistent infections in human intestinal cells. Virology 2004; 318:66-78. [PMID: 14972536 DOI: 10.1016/j.virol.2003.09.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Revised: 09/04/2003] [Accepted: 09/09/2003] [Indexed: 11/23/2022]
Abstract
Immunodeficient patients whose gut is chronically infected by vaccine-derived poliovirus (VDPV) may excrete large amounts of virus for years. To investigate how poliovirus (PV) establishes chronic infections in the gut, we tested whether it is possible to establish persistent VDPV infections in human intestinal Caco-2 cells. Four type 3 VDPV mutants, representative of the viral evolution in the gut of a hypogammaglobulinemic patient over almost 2 years [J. Virol. 74 (2000) 3001], were used to infect both undifferentiated, dividing cells, and differentiated, polarized enterocytes. A VDPV mutant excreted 36 days postvaccination by the patient was lytic in both types of intestinal cell cultures, like the parental Sabin 3 (S3) strain. In contrast, three VDPVs excreted 136, 442, and 637 days postvaccination, established persistent infections both in undifferentiated cells and in enterocytes. Thus, viral determinants selected between day 36 and 136 conferred on VDPV mutants the capacity to infect intestinal cells persistently. The percentage of persistently VDPV-infected cultures was higher in enterocytes than in undifferentiated cells, implicating cellular determinants involved in the differentiation of enterocytes in persistent VDPV infections. The establishment of persistent infections in enterocytes was not due to poor replication of VDPVs in these cells, but was associated with reduced viral adsorption to the cell surface.
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Affiliation(s)
- Karine Labadie
- Unité de Neurovirologie et Régénération du Système Nerveux, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
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35
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Mackey AD, McMahon RJ, Townsend JH, Gregory JF. Uptake, hydrolysis, and metabolism of pyridoxine-5'-beta-D-glucoside in Caco-2 cells. J Nutr 2004; 134:842-6. [PMID: 15051835 DOI: 10.1093/jn/134.4.842] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An important dietary source of vitamin B-6, pyridoxine-5'-beta-D-glucoside (PNG), exhibits only partial bioavailability, which is limited by the extent of enzymatic cleavage of the beta-glucosidic bond to release metabolically available pyridoxine (PN). This laboratory showed that the intestinal hydrolysis of PNG is catalyzed by cytosolic PNG hydrolase (PNGH) and brush border lactase-phlorizin hydrolase (LPH). LPH-catalyzed PNG hydrolysis in vitro is competitively inhibited by lactose. In the present study, the uptake and hydrolysis of PNG were examined in Caco-2 human colon carcinoma cells, which express a functional LPH but exhibit no PNGH activity. PNG uptake at 37 degrees C was linear over 5-500 micromol/L PNG. Uptake was not significantly reduced when Na(+) was substituted with K(+), Li(+), or Tris in the medium. Increasing PNG concentration in the medium did not change intracellular concentrations of PN, pyridoxamine (PM), pyridoxamine 5'-phosphate (PMP), or pyridoxal 5'-phosphate (PLP); however, intracellular pyridoxal (PL) concentration increased. Intracellular PNG concentration was not significantly reduced in the presence of lactose, but the concentration of PL declined in proportion to extracellular lactose (P = 0.01). These results indicate that PNG can be absorbed intact in a Na(+)-independent process and is taken up by passive diffusion. The presence of lactose in this in vitro model of intestinal uptake reduced the enzymatic hydrolysis of PNG by lactase.
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Affiliation(s)
- Amy D Mackey
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
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36
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Houle VM, Li W, Montgomery RK, Grand RJ. mRNA localization in polarized intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 2003; 284:G722-7. [PMID: 12490432 DOI: 10.1152/ajpgi.00458.2002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
An important feature of enterocyte maturation is the asymmetrical distribution of cellular functions including protein localization. mRNA sorting is one mechanism for establishment and maintenance of this process in other systems, and we have previously demonstrated differential localization of mRNAs in human enterocytes. To study regulation of mRNA sorting, we established a model in polarized Caco-2 cells. Proxy cDNA constructs containing beta-galactosidase (beta-gal)/green fluorescence protein (GFP) and the 3'-untranslated region (3'-UTR) of either human sucrase-isomaltase or villin were transfected transiently or stably. A control construct contained poly-A sequence in place of 3'-UTR. Expression of GFP was observed by confocal microscopy; intracellular location of the construct mRNA was imaged by in situ hybridization. The sucrase-isomaltase mRNA proxy localized to an apical position in Caco-2 cells as in native enterocytes; the villin mRNA proxy did not show significant localization. The control construct was not localized and was found diffusely throughout the cell. Proxy GFP proteins tended to localize with their mRNA proxies, but with less precision. This study establishes a valuable model for the investigation of mRNA localization in intestinal epithelial cells. Mechanisms controlling asymmetrical distribution of intestinal mRNAs can be now be elucidated.
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Affiliation(s)
- Vicki M Houle
- Gastrointestinal Cell Biology Research, Division of Gastroenterology and Nutrition, Harvard Digestive Disease Center, Children's Hospital, Harvard Medical School, Boston 02115, USA
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37
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Fleet JC, Wang L, Vitek O, Craig BA, Edenberg HJ. Gene expression profiling of Caco-2 BBe cells suggests a role for specific signaling pathways during intestinal differentiation. Physiol Genomics 2003; 13:57-68. [PMID: 12644633 DOI: 10.1152/physiolgenomics.00152.2002] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the pattern of gene expression resulting from spontaneous differentiation of Caco-2 BBe cells to gain insight into the molecular changes necessary for enterocyte differentiation. RNA was prepared from cells harvested at three cell stages: proliferating (50% confluent, 2 days in culture), postproliferative nondifferentiated (8 days), and differentiated (15 days). Gene expression profiles were determined using Affymetrix Human Genome U95A GeneChips. Differentially expressed genes were identified following statistical analysis (i.e., ANOVA, bootstrapping adjustments to P values, false detection rate criterion). We identified 1,150 unique genes as differentially expressed; expression of 48.6% fell and 46% increased from 2 to 15 days, while 5.4% had expression that either peaked or dipped at 8 days. Genes expressed during differentiation included several small-intestine-specific genes involved in nutrient transport/metabolism, e.g., DCT1, hephaestin, folate receptor 1, sucrase-isomaltase, and apolipoproteins CI, CIII, B100, H, and M, indicating that this colonic adenocarcinoma cell line has a hybrid colonocyte/enterocyte phenotype. Patterns of gene expression based upon functional classification suggest a role for cell-cell/cell-matrix interactions, suppression of Wnt signaling, and activation of TGFbeta and phosphatidylinositol 3-kinase pathways during enterocyte differentiation.
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Affiliation(s)
- James C Fleet
- Interdepartmental Nutrition Program, Purdue University, West Lafayette, Indiana 47907,
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38
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Rings EH, Boudreau F, Taylor JK, Moffett J, Suh ER, Traber PG. Phosphorylation of the serine 60 residue within the Cdx2 activation domain mediates its transactivation capacity. Gastroenterology 2001; 121:1437-50. [PMID: 11729123 DOI: 10.1053/gast.2001.29618] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Cdx2 is critical in intestinal proliferation and differentiation. Modulation of Cdx2 function in response to cellular signaling is to be elucidated. We hypothesize that phosphorylation of the Cdx2 activation domain can modulate its function. METHODS The Cdx2 activation domain was delineated in transient transfections using different portions of Cdx2 fused to the Gal4-DNA binding domain. In vivo phosphorylation was studied by metabolic labeling with (32)P-orthophosphate. To study a potential phosphorylation site, polyclonal antibodies were generated: CNL was raised against amino acids 54-66 of Cdx2 and P-Cdx2-S60 against the same epitope in which serine 60 was phosphorylated. RESULTS A critical region for transactivation resides within amino acids 60-70. Substitution of serine 60 with alanine reduces incorporation of (32)P-orthophosphate substantially. S60-phosphorylation decreases Cdx2 transactivation. Phosphorylation of serine 60 can be inhibited with the mitogen-activated protein kinase inhibitors PD98059 or UO126. P-Cdx2-S60 recognizes phosphorylated serine 60 mainly in proliferative compartment of the intestinal epithelial layer. In contrast, CNL recognizes Cdx2 predominantly in the differentiated compartment. CONCLUSIONS The Cdx2 activation domain is phosphorylated at serine 60 via the mitogen-activated protein kinase pathway. S60-phosphorylated and S60-nonphosphorylated Cdx2 have different transcriptional activity, as well as different spatial expression patterns in the intestinal epithelium.
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Affiliation(s)
- E H Rings
- Division of Gastroenterology, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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39
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Krasinski SD, Van Wering HM, Tannemaat MR, Grand RJ. Differential activation of intestinal gene promoters: functional interactions between GATA-5 and HNF-1 alpha. Am J Physiol Gastrointest Liver Physiol 2001; 281:G69-84. [PMID: 11408257 DOI: 10.1152/ajpgi.2001.281.1.g69] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of GATA-4, -5, and -6, hepatocyte nuclear factor-1 alpha (HNF-1 alpha) and -beta, and Cdx-2 on the rat and human lactase-phlorizin hydrolase (LPH) and human sucrase-isomaltase (SI) promoters were studied using transient cotransfection assays in Caco-2 cells. GATA factors and HNF-1 alpha were strong activators of the LPH promoters, whereas HNF-1 alpha and Cdx-2 were strong activators of the SI promoter, although GATA factors were also necessary for maximal activation of the SI gene. Cotransfection of GATA-5 and HNF-1 alpha together resulted in a higher activation of all three promoters than the sum of the activation by either factor alone, demonstrating functional cooperativity. In the human LPH promoter, an intact HNF-1 binding site was required for functional synergy. This study is the first to demonstrate 1) differential activation of the LPH and SI promoters by multiple transcription factors cotransfected singly and in combination and 2) that GATA and HNF-1 transcription factors cooperatively activate intestinal gene promoters. Synergistic activation is a mechanism by which higher levels of tissue-specific expression might be attained by overlapping expression of specific transcription factors.
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Affiliation(s)
- S D Krasinski
- Division of Pediatric Gastroenterology and Nutrition, Department of Pediatrics, The Floating Hospital for Children, New England Medical Center, and Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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40
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Cevallos AM, Zhang X, Waldor MK, Jaison S, Zhou X, Tzipori S, Neutra MR, Ward HD. Molecular cloning and expression of a gene encoding Cryptosporidium parvum glycoproteins gp40 and gp15. Infect Immun 2000; 68:4108-16. [PMID: 10858228 PMCID: PMC101706 DOI: 10.1128/iai.68.7.4108-4116.2000] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cryptosporidium parvum is a significant cause of diarrheal disease worldwide. The specific molecules that mediate C. parvum-host cell interactions and the molecular mechanisms involved in the pathogenesis of cryptosporidiosis are unknown. In this study we have shown that gp40, a mucin-like glycoprotein, is localized to the surface and apical region of invasive stages of the parasite and is shed from its surface. gp40-specific antibodies neutralize infection in vitro, and native gp40 binds specifically to host cells, implicating this glycoprotein in C. parvum attachment to and invasion of host cells. We have cloned and sequenced a gene designated Cpgp40/15 that encodes gp40 as well as gp15, an antigenically distinct, surface glycoprotein also implicated in C. parvum-host cell interactions. Analysis of the deduced amino acid sequence of the 981-bp Cpgp40/15 revealed the presence of an N-terminal signal peptide, a polyserine domain, multiple predicted O-glycosylation sites, a single potential N-glycosylation site, and a hydrophobic region at the C terminus, a finding consistent with what is required for the addition of a GPI anchor. There is a single copy of Cpgp40/15 in the C. parvum genome, and this gene does not contain introns. Our data indicate that the two Cpgp40/15-encoded proteins, gp40 and gp15, are products of proteolytic cleavage of a 49-kDa precursor protein which is expressed in intracellular stages of the parasite. The surface localization of gp40 and gp15 and their involvement in the host-parasite interaction suggest that either or both of these glycoproteins may serve as effective targets for specific preventive or therapeutic measures for cryptosporidiosis.
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Affiliation(s)
- A M Cevallos
- Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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41
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Turner JR. Show me the pathway! Regulation of paracellular permeability by Na(+)-glucose cotransport. Adv Drug Deliv Rev 2000; 41:265-81. [PMID: 10854686 DOI: 10.1016/s0169-409x(00)00046-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The physiological impact of Na(+)-nutrient cotransport-dependent regulation of intestinal tight junction permeability has been controversial. Nonetheless, increased permeability of small intestinal mucosae and enterocyte tight junctions as a consequence of Na(+)-nutrient cotransport has been documented by a significant number of in vivo and in vitro studies. Some details of the intracellular signaling events that regulate this process have been described recently. The aims of this article are to: (i) review studies of tight junction regulation and paracellular nutrient absorption in mammalian intestine, (ii) identify potential applications of tight junction regulation, and (iii) summarize recent progress in defining molecular mechanisms that lead to altered tight junction permeability.
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Affiliation(s)
- J R Turner
- Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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42
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Fang R, Santiago NA, Olds LC, Sibley E. The homeodomain protein Cdx2 regulates lactase gene promoter activity during enterocyte differentiation. Gastroenterology 2000; 118:115-27. [PMID: 10611160 DOI: 10.1016/s0016-5085(00)70420-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Lactase is the intestinal disaccharidase responsible for digestion of lactose, the predominant carbohydrate in milk. Transcription of the lactase gene is activated during enterocyte differentiation. We have characterized the interaction between the lactase promoter and Cdx2, a homeodomain protein involved in regulating intestinal development and differentiation. METHODS Nuclear protein bound to the lactase gene cis element, CE-LPH1, was analyzed by electrophoretic mobility shift assays and supershifts with Cdx2 antibody. Lactase promoter activities were assayed in cells transfected with luciferase reporter constructs and a Cdx2 expression construct. RESULTS Electrophoretic mobility shift assay with CE-LPH1 yields a specific DNA/protein complex that requires the caudal-related protein binding site, TTTAC. The complex is recognized by Cdx2 antibody and is more abundant in differentiated enterocytes. A Cdx2 expression construct is able to activate transcription driven by the wild-type, but not a mutated, promoter and results in increased endogenous lactase messenger RNA. CONCLUSIONS The homeodomain protein Cdx2 interacts with the lactase promoter and is capable of activating transcription of the endogenous gene. In contrast to a previous report, Cdx2 interaction with the lactase promoter correlates with enterocyte differentiation. These conclusions are consistent with the role of Cdx2 in regulating intestinal cell differentiation.
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Affiliation(s)
- R Fang
- Department of Pediatrics, Stanford University Medical Center, Stanford, California 94305, USA
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43
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Turner JR, Angle JM, Black ED, Joyal JL, Sacks DB, Madara JL. PKC-dependent regulation of transepithelial resistance: roles of MLC and MLC kinase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:C554-62. [PMID: 10484342 DOI: 10.1152/ajpcell.1999.277.3.c554] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms by which protein kinase C (PKC) activation results in increased transepithelial resistance (TER) are unknown [G. Hecht, B. Robinson, and A. Koutsouris. Am. J. Physiol. 266 (Gastrointest. Liver Physiol. 29): G214-G221, 1994]. We have previously shown that phosphorylation of the regulatory light chain of myosin II (MLC) is associated with decreases in TER and have suggested that contraction of the perijunctional actomyosin ring (PAMR) increases tight junction (TJ) permeability [J. R. Turner, B. K. Rill, S. L. Carlson, D. Carnes, R. Kerner, R. J. Mrsny, and J. L. Madara. Am. J. Physiol. 273 (Cell Physiol. 42): C1378-C1385, 1997]. We therefore hypothesized that PKC activation alters TER via relaxation of the PAMR. Activation of PKC by the phorbol ester phorbol 12-myristate 13-acetate (PMA) resulted in a progressive dose-dependent increase in TER that was apparent within 15 min (111% of controls) and maximal within 2 h (142% of controls). Similar increases were induced by a diacylglycerol analog, and the effects of both PMA and the diacylglycerol analog were prevented by the PKC inhibitor bisindolylmaleimide I. PMA treatment caused progressive decreases in MLC phosphorylation, by 12% at 15 min and 41% at 2 h. Phosphorylation of MLC kinase (MLCK) increased by 64% within 15 min of PMA treatment and was stable over 2 h (51% greater than that of controls). Thus increases in MLCK phosphorylation preceded decreases in MLC phosphorylation. These data suggest that PKC regulates TER via decreased phosphorylation of MLC, possibly due to inhibitory phosphorylation of MLCK. The decreased phosphorylation of MLC likely reduces PAMR tension, leading to decreased TJ permeability.
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Affiliation(s)
- J R Turner
- Department of Pathology,Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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Akompong T, Ramm E, Chang C, Yu ZK, Wessling-Resnick M. Immunological analysis of beta-thalassemic mouse intestinal proteins reveals up-regulation of sucrase-isomaltase in response to iron overload. J Nutr 1999; 129:949-52. [PMID: 10222384 DOI: 10.1093/jn/129.5.949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Maintenance of iron homeostasis must balance the demand for iron due to heme synthesis, which is driven by hematopoiesis, and the restricted intestinal uptake of iron, which otherwise limits absorption of this toxic element. The consequences of perturbed iron homeostasis are witnessed in inherited forms of beta-thalassemia in which erythroid hyperplasia results in enhanced intestinal iron absorption despite tissue iron overload. To gain a better understanding of intestinal factors that are induced when iron homeostasis is disrupted, a panel of monoclonal antibodies that recognize intestinal microvillous membrane proteins of the beta-thalassemic Hbbd(th3)/Hbbd(th3) mouse was established. The monoclonal antibodies were screened by differential Western blotting against normal and beta-thalassemic mouse intestine to identify antigens modulated in the disease state. Here we report the initial characterization of one immunoreactive species that is up-regulated in beta-thalassemic mouse intestine and the tentative identification of this antigen as sucrase-isomaltase. Studies in Caco-2 cells revealed the rather unexpected finding that expression of this intestinal hydrolase is increased in response to iron toxicity.
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Affiliation(s)
- T Akompong
- Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA
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45
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Weiss MD, DeMarco V, Strauss DM, Samuelson DA, Lane ME, Neu J. Glutamine synthetase: a key enzyme for intestinal epithelial differentiation? JPEN J Parenter Enteral Nutr 1999; 23:140-6. [PMID: 10338221 DOI: 10.1177/0148607199023003140] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND We have previously shown that glutamine synthetase protein and mRNA are concentrated in the crypt region of the rat small intestine and that the activity of this enzyme is highest around the time of weaning. This anatomical location and time of peak activity are sites and periods of active enterocyte differentiation. This led to our current hypothesis that glutamine synthetase is important in the differentiation of enterocytes. METHODS To test our hypothesis, we treated Caco-2 cells with physiologic (0.6 mM) glutamine concentrations in cell culture medium. The experimental group was treated with methionine sulfoximine, an irreversible glutamine synthetase inhibitor, and the control group with phosphate buffered saline. Three standard and well-defined markers of intestinal differentiation-sucrase-isomaltase activity, microvillus formation, and electrical impedance in transwell plates-were compared between the two groups. RESULTS The methionine-sulfoximine-inhibited group was found to have lower sucrase-isomaltase activity, a lower density of microvilli, and lower electrical impedance values over time compared with the control group. CONCLUSION The experimental group was found to be less differentiated by all three markers of differentiation. Therefore, glutamine synthetase is important for Caco-2 cell differentiation.
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Affiliation(s)
- M D Weiss
- Department of Pediatrics, University of Florida, Gainesville 32610, USA
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Spodsberg N, Troelsen JT, Carlsson P, Enerbäck S, Sjöström H, Norén O. Transcriptional regulation of pig lactase-phlorizin hydrolase: involvement of HNF-1 and FREACs. Gastroenterology 1999; 116:842-54. [PMID: 10092306 DOI: 10.1016/s0016-5085(99)70067-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND & AIMS One-kilobase sequence of the upstream fragment of the pig lactase-phlorizin hydrolase gene has been shown to control small intestinal-specific expression and postweaning decline of lactase-phlorizin hydrolase in transgenic mice. The aim of this study was to identify the regulatory DNA elements and transcription factors controlling lactase-phlorizin hydrolase expression. METHODS The activity of different lactase-phlorizin hydrolase promoter fragments was investigated by transfection experiments using Caco-2 cells. Electrophoretic mobility shift assays and supershift analyses were used to characterize the interaction between intestinal transcription factors and the identified regulatory elements. RESULTS Functional analysis revealed three previously undescribed regulatory regions in the lactase-phlorizin hydrolase promoter: a putative enhancer between -894 and -798 binding hepatocyte nuclear factor (HNF)-1 at position -894 to -880; a repressor-binding element between -278 to -264 to which an HNF-3-like factor is able to bind; and an element between -178 to -164 that binds an activating transcription factor. CONCLUSIONS Identification of three new regulatory regions and HNF-1 and HNF-3-like transcription factor as players in the regulation of lactase-phlorizin hydrolase gene transcription has an impact on the understanding of the molecular mechanisms behind age-dependent, tissue-specific, differentiation-dependent, and regional regulation of expression in the intestine.
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Affiliation(s)
- N Spodsberg
- Department of Medical Biochemistry and Genetics, Biochemical Laboratory C, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
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Abstract
Novel proteins of the Stat (signal transducers and activators of transcription) family have been associated with proliferation and differentiation of certain cells; the role of these transcription factors in gut differentiation has not been examined. The purpose of this study was to determine whether the cellular levels and actual binding of the Stat proteins are altered with intestinal differentiation using the Caco-2 cell line that spontaneously differentiates to a small bowel phenotype after confluency. We found that both Stat3 and Stat5 protein levels were increased in preconfluent and confluent Caco-2 cells; levels then decreased with postconfluency. Mobility shift assays demonstrated maximal binding of Stat3 and Stat5 at confluency and, similar to protein levels, binding activity decreased with postconfluency. The intestinal differentiation marker gene sucrase-isomaltase was increased by postconfluent day 1 with maximal levels by day 6. The progressive decrease of Stat3 and Stat5 protein levels and binding activity, occurring at a time associated with increased Caco-2 cell differentiation, suggests that a decrease in the cellular levels of these proteins may potentially play a role in subsequent intestinal cell differentiation. Delineating the cellular mechanisms responsible for intestinal differentiation is crucial to a better understanding of both normal gut development and aberrant gut growth.
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Affiliation(s)
- S Wang
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555-0533, USA
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Joe A, Verdon R, Tzipori S, Keusch GT, Ward HD. Attachment of Cryptosporidium parvum sporozoites to human intestinal epithelial cells. Infect Immun 1998; 66:3429-32. [PMID: 9632617 PMCID: PMC108364 DOI: 10.1128/iai.66.7.3429-3432.1998] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/1997] [Accepted: 04/08/1998] [Indexed: 02/07/2023] Open
Abstract
An enzyme-linked immunosorbent assay-based attachment model using the human intestinal cell line Caco-2A was developed to study attachment of Cryptosporidium parvum sporozoites in vitro and to assess potential inhibitors of sporozoite binding. In this system, attachment was related to sporozoite dose, incubation time, and host cell differentiation status. Polyclonal antibodies to C. parvum as well as glycoprotein inhibitors of a sporozoite lectin reduced attachment. This model will be a valuable tool in elucidating specific molecules and mechanisms involved in sporozoite-host cell attachment.
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Affiliation(s)
- A Joe
- Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Van Beers EH, Rings EH, Taminiau JA, Heymans HS, Einerhand AW, Dekker J, Büller HA. Regulation of lactase and sucrase-isomaltase gene expression in the duodenum during childhood. J Pediatr Gastroenterol Nutr 1998; 27:37-46. [PMID: 9669724 DOI: 10.1097/00005176-199807000-00007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
BACKGROUND In children, lactase and sucrase-isomaltase are essential intestinal glycohydrolases, and insufficiency of either enzyme causes diarrhea and malnutrition. Little is known about the regulation of lactase and sucrase-isomaltase expression in the duodenum during childhood. In this study, the mechanisms of regulation of duodenal expression of both enzymes were examined in a study population with ages ranging from 1 to 18 years. METHODS Duodenal biopsy specimens from 60 white children were used to analyze tissue morphology and to quantify lactase and sucrase-isomaltase mRNA and protein. RESULTS Among healthy subjects, high interindividual variability was noted in both mRNA and protein levels for lactase and sucrase-isomaltase. Lactase mRNA level per subject did not correlate with sucrase-isomaltase mRNA level and thus appeared independent. Both lactase and sucrase-isomaltase protein levels correlated significantly with their respective mRNA levels. For each enzyme, a significant inverse correlation was observed between the degree of villus atrophy and mRNA levels. Aging from 1 to 18 years did not result in significant changes in mRNA or protein levels of either enzyme. Immunostaining patterns within the duodenal epithelium for lactase differed from sucrase-isomaltase in adjacent sections, illustrating independent regulation at the cellular level. CONCLUSIONS In the duodenum of white children, lactase and sucrase-isomaltase seem primarily regulated at the transcriptional level. The expression of each enzyme in the intestinal epithelium is regulated by an independent mechanism. Lactase and sucrase-isomaltase exhibit stable mRNA and protein levels in healthy children as they grow to adulthood. Mucosal damage affected levels of both enzymes negatively.
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Affiliation(s)
- E H Van Beers
- Laboratory for Pediatric Gastroenterology and Nutrition, Academic Medical Center, University of Amsterdam, The Netherlands
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Delagebeaudeuf C, Gassama-Diagne A, Nauze M, Ragab A, Li RY, Capdevielle J, Ferrara P, Fauvel J, Chap H. Ectopic epididymal expression of guinea pig intestinal phospholipase B. Possible role in sperm maturation and activation by limited proteolytic digestion. J Biol Chem 1998; 273:13407-14. [PMID: 9593672 DOI: 10.1074/jbc.273.22.13407] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Guinea pig intestinal phospholipase B is a calcium-independent phospholipase hydrolyzing sequentially the acyl ester bonds at sn-2 and sn-1 positions of glycerophospholipids, promoting the formation of sn-glycero-3-phosphocholine from phosphatidylcholine. This 140-kDa glycoprotein from the brush border membrane of differentiated enterocytes contributes to lipid digestion as an ectoenzyme. The cDNA coding for guinea pig phospholipase B was revealed to be the homologue of AdRab-B, an mRNA appearing in rabbit upon intestine development. The sequence predicts a polypeptide of 1463 amino acids displaying four homologous repeats, two of them containing the lipase consensus sequence GXSXG. A 5-kilobase transcript was particularly abundant in mature ileal and jejunal enterocytes but was also detected in epididymis, where phospholipase B displayed a higher molecular mass (170 kDa versus 140 kDa in intestine), with no obvious evidence for enzyme activity. Trypsin treatment of phospholipase B immunoprecipitated from epididymal membranes reduced its size to 140 kDa, coinciding with the appearance of a significant phospholipase A2 activity. The same results were obtained in COS cells transfected with phospholipase B cDNA. Since sn-glycero-3-phosphocholine present at high concentrations in seminal plasma mainly stems from epididymis, this suggests a possible role of phospholipase B in male reproduction. This novel localization also unravels a mechanism of phospholipase B activation by limited proteolysis involving either trypsin in the intestinal lumen or a trypsin-like endopeptidase in the male reproductive tract.
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Affiliation(s)
- C Delagebeaudeuf
- Institut Fédératif de Recherche en Immunologie Cellulaire et Moléculaire, Université Paul Sabatier, Toulouse Cedex, France
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