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Nelli RK, Roth JA, Gimenez-Lirola LG. Distribution of Coronavirus Receptors in the Swine Respiratory and Intestinal Tract. Vet Sci 2022; 9:vetsci9090500. [PMID: 36136717 PMCID: PMC9504008 DOI: 10.3390/vetsci9090500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/06/2022] [Accepted: 09/11/2022] [Indexed: 11/16/2022] Open
Abstract
Coronaviruses use a broad range of host receptors for binding and cell entry, essential steps in establishing viral infections. This pilot study evaluated the overall distribution of angiotensin-converting enzyme 2 (ACE2), aminopeptidase N (APN), carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), and dipeptidyl peptidase 4 (DPP4) receptors in the pig respiratory and intestinal tract. All the receptors evaluated in this study were expressed and differentially distributed through the respiratory and intestinal tract. The presence and expression levels of these receptors could determine susceptibility to coronavirus infections. This study may have important implications for the development of research models and the assessment of the potential risk and introduction of novel coronaviruses into the swine population.
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Vieira da Silva I, P. Soares B, Pimpão C, M. A. Pinto R, Costa T, Freire JPB, Corrent E, Chalvon-Demersay T, Prates JAM, Lopes PA, Soveral G. Glutamine and cystine-enriched diets modulate aquaporins gene expression in the small intestine of piglets. PLoS One 2021; 16:e0245739. [PMID: 33465153 PMCID: PMC7815100 DOI: 10.1371/journal.pone.0245739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 01/07/2021] [Indexed: 12/13/2022] Open
Abstract
The regulation of glycerol permeability in the gastrointestinal tract is crucial to control fat deposition, lipolysis and gluconeogenesis. Knowing that the amino acid glutamine is a physiological regulator of gluconeogenesis, whereas cystine promotes adiposity, herein we investigated the effects of dietary supplementation with glutamine and cystine on the serum biochemical parameters of piglets fed on amino acid-enriched diets, as well as on the transcriptional profile of membrane water and glycerol channels aquaporins (AQPs) in the ileum portion of the small intestine and its impact on intestinal permeability. Twenty male piglets with an initial body weight of 8.8 ± 0.89 kg were allocated to four dietary treatments (n = 5) and received, during a four week-period, a basal diet without supplementation (control) or supplemented with 8 kg/ton of glutamine (Gln), cystine (Cys) or the combination of the two amino acids in equal proportions (Gln + Cys). Most biochemical parameters were found improved in piglets fed Gln and Cys diet. mRNA levels of AQP3 were found predominant over the others. Both amino acids, individually or combined, were responsible for a consistent downregulation of AQP1, AQP7 and AQP10, without impacting on water permeability. Conversely, Cys enriched diet upregulated AQP3 enhancing basolateral membranes glycerol permeability and downregulating glycerol kinase (GK) of intestinal cells. Altogether, our data reveal that amino acids dietary supplementation can modulate intestinal AQPs expression and unveil AQP3 as a promising target for adipogenesis regulation.
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Affiliation(s)
- Inês Vieira da Silva
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal
- Dept. Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Bárbara P. Soares
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal
- Dept. Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Catarina Pimpão
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal
- Dept. Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Rui M. A. Pinto
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal
- JCS, Laboratório de Análises Clínicas Dr. Joaquim Chaves, Algés, Portugal
| | - Teresa Costa
- Indukern Portugal, Lda., Centro Empresarial Sintra Estoril II, Sintra, Portugal
| | - João P. B. Freire
- LEAF—Linking Engineering, Agriculture and Food, Departamento de Ciências e Engenharia de Biossistemas, Instituto Superior de Agronomia (ISA), Universidade de Lisboa, Lisboa, Portugal
| | | | | | - José A. M. Prates
- CIISA—Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
| | - Paula A. Lopes
- CIISA—Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (PAL); (GS)
| | - Graça Soveral
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal
- Dept. Bioquímica e Biologia Humana, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (PAL); (GS)
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3
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Abstract
The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.
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Affiliation(s)
- Patrick E Hanna
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - M W Anders
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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4
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Picariello G, Ferranti P, Addeo F. Use of brush border membrane vesicles to simulate the human intestinal digestion. Food Res Int 2016. [DOI: 10.1016/j.foodres.2015.11.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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5
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Michael Danielsen E, Hansen GH. Small molecule pinocytosis and clathrin-dependent endocytosis at the intestinal brush border: Two separate pathways into the enterocyte. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:233-43. [PMID: 26615917 DOI: 10.1016/j.bbamem.2015.11.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/20/2015] [Accepted: 11/21/2015] [Indexed: 12/30/2022]
Abstract
Pinocytosis at the small intestinal brush border was studied in postweaned porcine cultured mucosal explants, using the fluorescent polar probes Alexa hydrazide (AH, MW 570), Texas red dextran (TRD, MW ~ 3000), and Cascade blue dextran (CBD, MW ~ 10,000). Within 1 h, AH appeared in a string of subapical punctae in enterocytes, indicative of an ongoing constitutive pinocytosis. By comparison, TRD was taken up less efficiently into the same compartment, and no intracellular labeling of CBD was detectable, indicating that only small molecules are pinocytosed from the postweaned gut lumen. AH remained in the terminal web region in EEA-1-positive endosomes (“TWEEs”) for at least 2 h, implying that the pinocytic uptake does not proceed towards a transcytic pathway. Like AH, cholera toxin B subunit (CTB) was readily internalized, but the two probes appeared in completely non-overlapping subapical compartments, indicating the existence of two different uptake mechanisms operating simultaneously at the brush border. CTB is internalized by clathrin-dependent receptor mediated endocytosis, but surprisingly the toxin also caused a rapid disappearance from the apical cell surface of two major brush border enzymes, alkaline phosphatase and aminopeptidase N, demonstrating the disruptive effect of this pathway. By immunofluorescence, caveolin-1 was hardly detectable in enterocytes, arguing against a caveolae-mediated uptake of AH, whereas the pinocytosis/phagocytosis inhibitors dimethyl amiloride and cytochalasin D both arrested AH uptake. We propose that the constitutive pinocytic mechanism visualized by AH contributes to maintenance of membrane homeostasis and to enrich the contents of lipid raft constituents at the brush border.
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Affiliation(s)
- E Michael Danielsen
- Department of Cellular and Molecular Medicine, The Panum Institute, Faculty of Health Sciences, University of Copenhagen, Denmark.
| | - Gert H Hansen
- Department of Cellular and Molecular Medicine, The Panum Institute, Faculty of Health Sciences, University of Copenhagen, Denmark
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6
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Danielsen EM, Hansen GH, Rasmussen K, Niels-Christiansen LL. Permeabilization of enterocytes induced by absorption of dietary fat. Mol Membr Biol 2013; 30:261-72. [DOI: 10.3109/09687688.2013.780642] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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7
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Asanuma-Date K, Hirano Y, Le N, Sano K, Kawasaki N, Hashii N, Hiruta Y, Nakayama KI, Umemura M, Ishikawa K, Sakagami H, Ogawa H. Functional regulation of sugar assimilation by N-glycan-specific interaction of pancreatic α-amylase with glycoproteins of duodenal brush border membrane. J Biol Chem 2012; 287:23104-18. [PMID: 22584580 DOI: 10.1074/jbc.m111.314658] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Porcine pancreatic α-amylase (PPA) binds to N-linked glycans of glycoproteins (Matsushita, H., Takenaka, M., and Ogawa, H. (2002) J. Biol Chem., 277, 4680-4686). Immunostaining revealed that PPA is located at the brush-border membrane (BBM) of enterocytes in the duodenum and that the binding is inhibited by mannan but not galactan, indicating that PPA binds carbohydrate-specifically to BBM. The ligands for PPA in BBM were identified as glycoprotein N-glycans that are significantly involved in the assimilation of glucose, including sucrase-isomaltase (SI) and Na(+)/Glc cotransporter 1 (SGLT1). Binding of SI and SGLT1 in BBM to PPA was dose-dependent and inhibited by mannan. Using BBM vesicles, we found functional changes in PPA and its ligands in BBM due to the N-glycan-specific interaction. The starch-degrading activity of PPA and maltose-degrading activity of SI were enhanced to 240 and 175%, respectively, while Glc uptake by SGLT1 was markedly inhibited by PPA at high but physiologically possible concentrations, and the binding was attenuated by the addition of mannose-specific lectins, especially from Galanthus nivalis. Additionally, recombinant human pancreatic α-amylases expressed in yeast and purified by single-step affinity chromatography exhibited the same carbohydrate binding specificity as PPA in binding assays with sugar-biotinyl polymer probes. The results indicate that mammalian pancreatic α-amylases share a common carbohydrate binding activity and specifically bind to the intestinal BBM. Interaction with N-glycans in the BBM activated PPA and SI to produce much Glc on the one hand and to inhibit Glc absorption by enterocytes via SGLT1 in order to prevent a rapid increase in blood sugar on the other.
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Affiliation(s)
- Kimie Asanuma-Date
- Graduate School of Humanities and Sciences and the Glycoscience Institute, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
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Abstract
Chemical genetics is an emerging research field that utilises biologically active small molecules to study biological functions of genes and their products. The direct regulation of the protein function by the biologically active small molecules can alternate the gene mutagenesis studies utilised in conventional genetics. Like conventional genetics, chemical genetics can be divided into two concepts - 'forward' and 'reverse' chemical genetics. These approaches of chemical genetics have a tremendous impact on both functional genomics and drug development. This review focuses on the two ways in which chemical genetics can be used for therapeutic target mining and their practical application in drug development, particularly, in angiogenesis-related diseases.
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Affiliation(s)
- Joong Sup Shim
- Sejong University, Chemical Genomics National Research Laboratory, Department of Bioscience and Biotechnology, Institute of Bioscience, Seoul 143-747, Korea
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9
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Waagepetersen HS, Hansen GH, Fenger K, Lindsay JG, Gibson G, Schousboe A. Cellular mitochondrial heterogeneity in cultured astrocytes as demonstrated by immunogold labeling of α-ketoglutarate dehydrogenase. Glia 2005; 53:225-31. [PMID: 16206171 DOI: 10.1002/glia.20276] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In brain cells, various metabolites and metabolic pathways, largely of mitochondrial origin, have been shown to be compartmentalized. Attention has therefore been focused on the possible existence of mitochondrial heterogeneity in the brain at the cellular level. To determine whether mitochondria in cultured cortical and cerebellar astrocytes are heterogeneous at the single cell level, immunogold electron microscopy and an antibody against the alpha-ketoglutarate dehydrogenase component of the alpha-ketoglutarate dehydrogenase complex, a marker enzyme for the tricarboxylic acid (TCA) cycle, were employed. The number of gold particles was counted in the mitochondria of 36 and 42 cells from cultured cerebellar and cortical astrocytes, respectively. A test for random distribution (Poisson distribution) of mitochondria according to the number of gold particles was subsequently performed for every one of the 36 and 42 cells as the ratio variance/mean (= index of dispersion). This should be approximately distributed as chi2/degrees of freedom (df) = n - 1, n = number of mitochondria), if the observations obeyed a Poisson distribution. For 26 of the 36 (cerebellar astrocytes) distributions and for 28 of the 42 (cortical astrocytes) distributions a random distribution had to be rejected. These findings therefore strongly indicate that alpha-ketoglutarate dehydrogenase is heterogeneously distributed in mitochondria within individual astrocytes originating either from cerebellum or cerebral cortex. In conclusion, this study underlines the probability that mitochondrial heterogeneity at the single cell level might be extended to involve other metabolic pathways and metabolites.
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Affiliation(s)
- Helle S Waagepetersen
- Department of Pharmacology, Danish University of Pharmaceutical Sciences, Copenhagen, Denmark
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10
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Jardinaud F, Banisadr G, Noble F, Mélik-Parsadaniantz S, Chen H, Dugave C, Laplace H, Rostène W, Fournié-Zaluski MC, Roques BP, Popovici T. Ontogenic and adult whole body distribution of aminopeptidase N in rat investigated by in vitro autoradiography. Biochimie 2004; 86:105-13. [PMID: 15016448 DOI: 10.1016/j.biochi.2003.12.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2003] [Accepted: 12/23/2003] [Indexed: 01/09/2023]
Abstract
Aminopeptidase N (APN), which is widely distributed in mammalian tissues, is able to cleave numerous regulatory peptides. The selective inhibitor of APN, [(125)I] RB129, has been used to study the distribution of this exopeptidase during rat prenatal development and adult life by in vitro whole-body autoradiography. In the central nervous system, APN shows a weak labeling compared to the major part of the non-nervous tissues in the embryo and in the adult. APN is progressively expressed in kidney, intestine, heart, lung, sensory organs, eye, and thymus. In organs such as the liver, the cartilages and the bones, altered levels of APN expression are observed during the development, or in the embryo compared to the adult, suggesting a role of APN during the liver haematopoiesis and bone growth. At this time, all the physiological functions of APN are still incompletely known, however its developmental pattern of expression strongly suggests a function of modulation of this enzyme during the development, next in physiological and/or pathological situations in adult. In this way, APN could represent a new therapeutic target in pathological processes, such as tumoral proliferation and/or angiogenesis associated with cancer development, where an increase in the level of this enzyme has been observed.
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Affiliation(s)
- Fanny Jardinaud
- Département de Pharmacochimie Moléculaire & Structurale, Inserm U266, CNRS FRE 2463, UFR des Sciences Pharmaceutiques & Biologiques, 4, avenue de l'Observatoire, 75270 Paris cedex, France
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11
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Hansen GH, Pedersen J, Niels-Christiansen LL, Immerdal L, Danielsen EM. Deep-apical tubules: dynamic lipid-raft microdomains in the brush-border region of enterocytes. Biochem J 2003; 373:125-32. [PMID: 12689332 PMCID: PMC1223483 DOI: 10.1042/bj20030235] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2003] [Revised: 04/02/2003] [Accepted: 04/10/2003] [Indexed: 11/17/2022]
Abstract
The brush border of small intestinal enterocytes is highly enriched in cholesterol- and glycosphingolipid-containing membrane microdomains, commonly termed as lipid 'rafts'. Functionally, transcytosis of IgA and exocytosis of newly made brush-border proteins in enterocytes occur through apical lipid raft-containing compartments, but little is otherwise known about these raft microdomains. We therefore studied in closer detail apical lipid-raft compartments in enterocytes by immunogold electron microscopy and biochemical analyses. Novel membrane structures, deep-apical tubules, were visualized by the non-permeable surface marker Ruthenium Red in the brush-border region of the cells. The surface-connected tubules were labelled by antibodies to caveolin-1 and the glycolipid asialo G(M1), and they were sensitive to cholesterol depletion by methyl-beta-cyclodextrin, indicating the presence of raft microdomains. Deep-apical tubules were positioned close to the actin rootlets of adjacent microvilli in the terminal web region, which had a diameter of 50-100 nm, and penetrated up to 1 microm into the cytoplasm. Markers for transcytosis, IgA and the polymeric immunoglobulin receptor, as well as the resident brush-border enzyme aminopeptidase N, were present in these deep-apical tubules. We propose that deep-apical tubules are a specialized lipid-raft microdomain in the brush-border region functioning as a hub in membrane trafficking at the brush border. In addition, the sensitivity to cholesterol depletion suggests that deep-apical tubules function as a cell-surface membrane reservoir for cholesterol and for rapid adaptive changes in the size of microvilli at the brush border.
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Affiliation(s)
- Gert H Hansen
- Department of Medical Biochemistry and Genetics, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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12
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Hansen GH, Immerdal L, Thorsen E, Niels-Christiansen LL, Nystrøm BT, Demant EJ, Danielsen EM. Lipid rafts exist as stable cholesterol-independent microdomains in the brush border membrane of enterocytes. J Biol Chem 2001; 276:32338-44. [PMID: 11389144 DOI: 10.1074/jbc.m102667200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Glycosphingolipid/cholesterol-rich membranes ("rafts")can be isolated from many types of cells, but their existence as stable microdomains in the cell membrane has been elusive. Addressing this problem, we studied the distribution of galectin-4, a raft marker, and lactase, a protein excluded from rafts, on microvillar vesicles from the enterocyte brush border membrane. Magnetic beads coated with either anti-galectin-4 or anti-lactase antibodies were used for immunoisolation of vesicles followed by double immunogold labeling of the two proteins. A morphometric analysis revealed subpopulations of raft-rich and raft-poor vesicles by the following criteria: 1) the lactase/galectin-4 labeling ratio/vesicle captured by the anti-lactase beads was significantly higher (p < or = 0.01) than that of vesicles captured by anti-galectin-4 beads, 2) subpopulations of vesicles labeled by only one of the two antibodies were preferentially captured by beads coated with the respective antibody (p < or = 0.01), 3) the average diameter of "galectin-4 positive only" vesicles was smaller than that of vesicles labeled for lactase. Surprisingly, pretreatment with methyl-beta-cyclodextrin, which removed >70% of microvillar cholesterol, did not affect the microdomain localization of galectin-4. We conclude that stable, cholesterol-independent raft microdomains exist in the enterocyte brush border.
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Affiliation(s)
- G H Hansen
- Department of Medical Biochemistry and Genetics, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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13
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Hansen GH, Niels-Christiansen LL, Thorsen E, Immerdal L, Danielsen EM. Cholesterol depletion of enterocytes. Effect on the Golgi complex and apical membrane trafficking. J Biol Chem 2000; 275:5136-42. [PMID: 10671559 DOI: 10.1074/jbc.275.7.5136] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intestinal brush border enzymes, including aminopeptidase N and sucrase-isomaltase, are associated with "rafts" (membrane microdomains rich in cholesterol and sphingoglycolipids). To assess the functional role of rafts in the present work, we studied the effect of cholesterol depletion on apical membrane trafficking in enterocytes. Cultured mucosal explants of pig small intestine were treated for 2 h with the cholesterol sequestering agent methyl-beta-cyclodextrin and lovastatin, an inhibitor of hydroxymethylglutaryl-coenzyme A reductase. The treatment reduced the cholesterol content >50%. Morphologically, the Golgi complex/trans-Golgi network was partially transformed into numerous 100-200 nm vesicles. By immunogold electron microscopy, aminopeptidase N was localized in these Golgi-derived vesicles as well as at the basolateral cell surface, indicating a partial missorting. Biochemically, the rates of the Golgi-associated complex glycosylation and association with rafts of newly synthesized aminopeptidase N were reduced, and less of the enzyme had reached the brush border membrane after 2 h of labeling. In contrast, the basolateral Na(+)/K(+)-ATPase was neither missorted nor raft-associated. Our results implicate the Golgi complex/trans-Golgi network in raft formation and suggest a close relationship between this event and apical membrane trafficking.
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Affiliation(s)
- G H Hansen
- Department of Medical Biochemistry and Genetics, the Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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14
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Naim HY, Joberty G, Alfalah M, Jacob R. Temporal association of the N- and O-linked glycosylation events and their implication in the polarized sorting of intestinal brush border sucrase-isomaltase, aminopeptidase N, and dipeptidyl peptidase IV. J Biol Chem 1999; 274:17961-7. [PMID: 10364244 DOI: 10.1074/jbc.274.25.17961] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The temporal association between O-glycosylation and processing of N-linked glycans in the Golgi apparatus as well as the implication of these events in the polarized sorting of three brush border proteins has been the subject of the current investigation. O-Glycosylation of pro-sucrase-isomaltase (pro-SI), aminopeptidase N (ApN), and dipeptidyl peptidase IV (DPPIV) is drastically reduced when processing of the mannose-rich N-linked glycans is blocked by deoxymannojirimycin, an inhibitor of the Golgi-located mannosidase I. By contrast, O-glycosylation is not affected in the presence of swainsonine, an inhibitor of Golgi mannosidase II. The results indicate that removal of the outermost mannose residues by mannosidase I from the mannose-rich N-linked glycans is required before O-glycosylation can ensue. On the other hand, subsequent mannose residues in the core chain impose no sterical constraints on the progression of O-glycosylation. Reduction or modification of N- and O-glycosylation do not affect the transport of pro-SI, ApN, or DPPIV to the cell surface per se. However, the polarized sorting of two of these proteins, pro-SI and DPPIV, to the apical membrane is substantially altered when O-glycans are not completely processed, while the sorting of ApN is not affected. The processing of N-linked glycans, on the other hand, has no influence on sorting of all three proteins. The results indicate that O-linked carbohydrates are at least a part of the sorting mechanism of pro-SI and DPPIV. The sorting of ApN implicates neither O-linked nor N-linked glycans and is driven most likely by carbohydrate-independent mechanisms.
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Affiliation(s)
- H Y Naim
- Department of Physiological Chemistry, School of Veterinary Medicine Hannover, Bünteweg 17, D-30559 Hannover, Germany.
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15
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Abstract
BACKGROUND Development of the small intestine is essential for proper nutrition of the fetus and the neonate. This investigation examines the morphogenesis and cytodifferentiation of developing fetal porcine small intestinal mucosa. METHODS Fetuses were collected from gilts after hysterectomy. Small intestinal segments were removed and processed for light and electron microscopy. RESULTS Fetal porcine small intestine developed from a simple tube of stratified epithelium to a tube containing villus and intervillus regions of simple columnar epithelium. This development occurred in a proximal to distal direction. By Day 40 of gestation, cytodifferentiation was evident with the presence of goblet cells and enteroendocrine cells in the duodenum. As development progressed, microvilli lengthened and components of the apical endocytic complex (AEC) were observed. By Day 110 of gestation, tubular and vesicular components of the AEC were confined to the jejunum, whereas large lysosomal vacuoles were observed in the distal jejunum. Duodenal epithelium at Day 110 was similar to postnatal epithelium. CONCLUSIONS The pattern of fetal porcine small intestinal development is similar to that reported for fetal human small intestine. Villus development and cytodifferentiation occur at similar relative times in gestation when compared to the human. These observations support the use of the fetal pig as a model for investigations of human small intestinal development.
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Affiliation(s)
- C M Dekaney
- Department of Veterinary Anatomy and Public Health, Texas A&M University, College Station 77843-4458, USA
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