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Li K, Wang A, Diao Y, Fan S. Oxidative medicine and cellular longevity the role and mechanism of NCOA4 in ferroptosis induced by intestinal ischemia reperfusion. Int Immunopharmacol 2024; 133:112155. [PMID: 38688134 DOI: 10.1016/j.intimp.2024.112155] [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: 02/22/2024] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Ferroptosis is an iron-dependent and cystathione-non-dependent non-apoptotic cell death characterized by elevated intracellular free iron levels and reduced antioxidant capacity, leading to the accumulation of lipid peroxides. Nuclear receptor coactivator 4 (NCOA4) mediates ferritinophagy, increasing labile iron levels, which can result in oxidative damage. However, the specific mechanism of NCOA4-mediated ferritinophagy in intestinal ischemia-reperfusion and the underlying mechanisms have not been reported in detail. OBJECT 1. To investigate the role of NCOA4 in ferroptosis of intestinal epithelial cells induced by II/R injury in mouse. 2. To investigate the mechanism of action of NCOA4-induced ferroptosis. METHODS 1. Construct a mouse II/R injury model and detect ferroptosis related markers such as HE staining, immunohistochemistry, ELISA, and WB methods. 2. Detect expression of NCOA4 in the intestine of mouse with II/R injury model and analyze its correlation with intestinal ferroptosis in mouse with II/R injury model. 3. Construct an ischemia-reperfusion model at the cellular level through hypoxia and reoxygenation, and overexpress/knockdown NCOA4 to detect markers related to ferroptosis. Based on animal experimental results, analyze the correlation and mechanism of action between NCOA4 and intestinal epithelial ferroptosis induced by II/R injury in mouse. RESULTS 1. Ferroptosis occurred in the intestinal epithelial cells of II/R-injured mouse, and the expression of critical factors of ferroptosis, ACSL4, MDA and 15-LOX, was significantly increased, while the levels of GPX4 and GSH were significantly decreased. 2. The expression of NCOA4 in the intestinal epithelium of mouse with II/R injure was significantly increased, the expression of ferritin was significantly decreased, and the level of free ferrous ions was significantly increased; the expression of autophagy-related proteins LC3 and Beclin-1 protein was increased, and the expression of P62 was decreased, and these changes were reversed by autophagy inhibitors. 3. Knockdown of NCOA4 at the cellular level resulted in increased ferritin expression and decreased ferroptosis, and CO-IP experiments suggested that NCOA4 can bind to ferritin, which suggests that NCOA4 most likely mediates ferritinophagy to induce ferroptosis. CONCLUSION This thesis explored the role of NCOA4 in II/R injury in mice and the mechanism of action. The research results suggest that NCOA4 can mediate ferritinophagy to induce ferroptosis during II/R injury. This experiment reveals the pathological mechanism of II/R injury and provides some scientific basis for the development of drugs for the treatment of II/R injury based on the purpose of alleviating ferroptosis.
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Affiliation(s)
- Kun Li
- College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China.
| | - Annan Wang
- College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Yunpeng Diao
- College of Pharmacy, Dalian Medical University, Dalian, 116044, China
| | - Shuyuan Fan
- College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China.
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2
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Vanhaesebroeck B, Perry MWD, Brown JR, André F, Okkenhaug K. PI3K inhibitors are finally coming of age. Nat Rev Drug Discov 2021; 20:741-769. [PMID: 34127844 PMCID: PMC9297732 DOI: 10.1038/s41573-021-00209-1] [Citation(s) in RCA: 216] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2021] [Indexed: 01/08/2023]
Abstract
Overactive phosphoinositide 3-kinase (PI3K) in cancer and immune dysregulation has spurred extensive efforts to develop therapeutic PI3K inhibitors. Although progress has been hampered by issues such as poor drug tolerance and drug resistance, several PI3K inhibitors have now received regulatory approval - the PI3Kα isoform-selective inhibitor alpelisib for the treatment of breast cancer and inhibitors mainly aimed at the leukocyte-enriched PI3Kδ in B cell malignancies. In addition to targeting cancer cell-intrinsic PI3K activity, emerging evidence highlights the potential of PI3K inhibitors in cancer immunotherapy. This Review summarizes key discoveries that aid the clinical translation of PI3Kα and PI3Kδ inhibitors, highlighting lessons learnt and future opportunities.
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Affiliation(s)
| | - Matthew W D Perry
- Medicinal Chemistry, Research and Early Development, Respiratory & Immunology BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Jennifer R Brown
- CLL Center, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Fabrice André
- Institut Gustave Roussy, INSERM U981, Université Paris Saclay, Paris, France
| | - Klaus Okkenhaug
- Department of Pathology, University of Cambridge, Cambridge, UK
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Feng G, Han K, Li Y, Yang Q, Feng W, Wang J, Yang X. Undigestible Gliadin Peptide Nanoparticles Penetrate Mucus and Reduce Mucus Production Driven by Intestinal Epithelial Cell Damage. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:7979-7989. [PMID: 34251199 DOI: 10.1021/acs.jafc.1c02177] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Wheat protein is the most consumed plant protein in our diet, and there is an increased prevalence of wheat/gluten intolerance and adherence to a gluten-free diet in many countries. Despite the known immunodominant effect of undigested gliadin peptides responsible for gluten-related intolerance, it remains unclear if and how gliadin peptides self-assemble into ordered nanostructures during gastrointestinal digestion, as well as their biological impact on the mucus barrier function. In this study, we purified undigestible gliadin peptide nanoparticles (UGPNs) by ultracentrifugation and characterized their structural and physiochemical properties. The results demonstrate that the UGPNs are self-assembled nanostructures generated by cationic amino acids (Lys and Arg)-capped surfactant-like peptides (SLPs), mainly derived from γ-gliadin and α-gliadin. SLPs trigger the concentration-dependent self-assembly driven by β-sheet conformational transitions above their critical aggregation concentration (cac, ∼0.1 mg/mL). UGPNs can easily penetrate the mucus layer in Caco-2/HT29-MTX cocultures with a high Papp value (∼5.7 × 10-6 cm/s) and reduce the production and thickness of the mucus layer driven by intestinal epithelial cell damage. Isothermal titration calorimetry and Langmuir monolayer studies indicate that the self-assembled state of UGPNs significantly affects their binding to DPPC/DOPE lipid membrane models. These results highlight the relevance of the self-assembly of gliadin peptides as a trigger of mucosal inflammation-related wheat/gluten intolerance.
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Affiliation(s)
- Guangxin Feng
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Kaining Han
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Yanlei Li
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Qian Yang
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Weiting Feng
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Jinmei Wang
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
| | - Xiaoquan Yang
- Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China
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4
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Asowata EO, Olusanya O, Abaakil K, Chichger H, Srai SKS, Unwin RJ, Marks J. Diet-induced iron deficiency in rats impacts small intestinal calcium and phosphate absorption. Acta Physiol (Oxf) 2021; 232:e13650. [PMID: 33749990 DOI: 10.1111/apha.13650] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 02/26/2021] [Accepted: 03/17/2021] [Indexed: 12/31/2022]
Abstract
AIMS Recent reports suggest that iron deficiency impacts both intestinal calcium and phosphate absorption, although the exact transport pathways and intestinal segment responsible have not been determined. Therefore, we aimed to systematically investigate the impact of iron deficiency on the cellular mechanisms of transcellular and paracellular calcium and phosphate transport in different regions of the rat small intestine. METHODS Adult, male Sprague-Dawley rats were maintained on a control or iron-deficient diet for 2 weeks and changes in intestinal calcium and phosphate uptake were determined using the in situ intestinal loop technique. The circulating levels of the hormonal regulators of calcium and phosphate were determined by ELISA, while the expression of transcellular calcium and phosphate transporters, and intestinal claudins were determined using qPCR and western blotting. RESULTS Diet-induced iron deficiency significantly increased calcium absorption in the duodenum but had no impact in the jejunum and ileum. In contrast, phosphate absorption was significantly inhibited in the duodenum and to a lesser extent the jejunum, but remained unchanged in the ileum. The changes in duodenal calcium and phosphate absorption in the iron-deficient animals were associated with increased claudin 2 and 3 mRNA and protein levels, while levels of parathyroid hormone, fibroblast growth factor-23 and 1,25-dihydroxy vitamin D3 were unchanged. CONCLUSION We propose that iron deficiency alters calcium and phosphate transport in the duodenum. This occurs via changes to the paracellular pathway, whereby upregulation of claudin 2 increases calcium absorption and upregulation of claudin 3 inhibits phosphate absorption.
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Affiliation(s)
- Evans O. Asowata
- Department of Neuroscience, Physiology & Pharmacology University College London London UK
| | - Oluwatobi Olusanya
- Department of Neuroscience, Physiology & Pharmacology University College London London UK
| | - Kaoutar Abaakil
- Department of Neuroscience, Physiology & Pharmacology University College London London UK
| | - Havovi Chichger
- Biomedical Research Group School of Life Sciences Anglia Ruskin University Cambridge UK
| | - Surjit K. S. Srai
- Institute of Structural and Molecular Biology University College London London UK
| | - Robert J. Unwin
- Department of Renal Medicine University College London London UK
| | - Joanne Marks
- Department of Neuroscience, Physiology & Pharmacology University College London London UK
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5
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Korner JL, Stephenson EB, Elvira KS. A bespoke microfluidic pharmacokinetic compartment model for drug absorption using artificial cell membranes. LAB ON A CHIP 2020; 20:1898-1906. [PMID: 32322848 DOI: 10.1039/d0lc00263a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Early prediction of the rate and extent of intestinal absorption is vital for the efficient development of orally administered drugs. Here we show a new type of pharmacokinetic compartment model that shows a threefold improvement in the prediction of molecular absorption in the jejunum than the current state-of-the-art in vitro technique, parallel artificial membrane permeability assays (PAMPA). Our three-stage pharmacokinetic compartment model uses microfluidic droplets and bespoke, biomimetic artificial cells to model the path of a drug proxy from the intestinal space into the blood via an enterocyte. Each droplet models the buffer and salt composition of each pharmacokinetic compartment. The artificial cell membranes are made from the major components of human intestinal cell membranes (l-α-phosphatidylcholine, PC and l-α-phosphatidylethanolamine, PE) and sizes are comparable to human cells (∼0.5 nL). We demonstrate the use of the microfluidic platform to quantify common pharmacokinetic parameters such as half-life, flux and the apparent permeability coefficient (Papp). Our determined Papp more closely resembles that of actual intestinal tissue than PAMPA, which overestimates it by a factor of 20.
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Affiliation(s)
- Jaime L Korner
- Department of Chemistry, University of Victoria, Victoria, BC, Canada.
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6
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Grassi S, Giussani P, Mauri L, Prioni S, Sonnino S, Prinetti A. Lipid rafts and neurodegeneration: structural and functional roles in physiologic aging and neurodegenerative diseases. J Lipid Res 2020; 61:636-654. [PMID: 31871065 PMCID: PMC7193971 DOI: 10.1194/jlr.tr119000427] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/11/2019] [Indexed: 12/14/2022] Open
Abstract
Lipid rafts are small, dynamic membrane areas characterized by the clustering of selected membrane lipids as the result of the spontaneous separation of glycolipids, sphingolipids, and cholesterol in a liquid-ordered phase. The exact dynamics underlying phase separation of membrane lipids in the complex biological membranes are still not fully understood. Nevertheless, alterations in the membrane lipid composition affect the lateral organization of molecules belonging to lipid rafts. Neural lipid rafts are found in brain cells, including neurons, astrocytes, and microglia, and are characterized by a high enrichment of specific lipids depending on the cell type. These lipid rafts seem to organize and determine the function of multiprotein complexes involved in several aspects of signal transduction, thus regulating the homeostasis of the brain. The progressive decline of brain performance along with physiological aging is at least in part associated with alterations in the composition and structure of neural lipid rafts. In addition, neurodegenerative conditions, such as lysosomal storage disorders, multiple sclerosis, and Parkinson's, Huntington's, and Alzheimer's diseases, are frequently characterized by dysregulated lipid metabolism, which in turn affects the structure of lipid rafts. Several events underlying the pathogenesis of these diseases appear to depend on the altered composition of lipid rafts. Thus, the structure and function of lipid rafts play a central role in the pathogenesis of many common neurodegenerative diseases.jlr;61/5/636/F1F1f1.
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Affiliation(s)
- Sara Grassi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Paola Giussani
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Laura Mauri
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Simona Prioni
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Sandro Sonnino
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Alessandro Prinetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy. mailto:
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7
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Ischemia-induced ACSL4 activation contributes to ferroptosis-mediated tissue injury in intestinal ischemia/reperfusion. Cell Death Differ 2019; 26:2284-2299. [PMID: 30737476 PMCID: PMC6889315 DOI: 10.1038/s41418-019-0299-4] [Citation(s) in RCA: 544] [Impact Index Per Article: 108.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/06/2019] [Accepted: 01/23/2019] [Indexed: 12/19/2022] Open
Abstract
Ferroptosis is a recently identified form of regulated cell death defined by the iron-dependent accumulation of lipid reactive oxygen species. Ferroptosis has been studied in various diseases such as cancer, Parkinson's disease, and stroke. However, the exact function and mechanism of ferroptosis in ischemia/reperfusion (I/R) injury, especially in the intestine, remains unknown. Considering the unique conditions required for ferroptosis, we hypothesize that ischemia promotes ferroptosis immediately after intestinal reperfusion. In contrast to conventional strategies employed in I/R studies, we focused on the ischemic phase. Here we verified ferroptosis by assessing proferroptotic changes after ischemia along with protein and lipid peroxidation levels during reperfusion. The inhibition of ferroptosis by liproxstatin-1 ameliorated I/R-induced intestinal injury. Acyl-CoA synthetase long-chain family member 4 (ACSL4), which is a key enzyme that regulates lipid composition, has been shown to contribute to the execution of ferroptosis, but its role in I/R needs clarification. In the present study, we used rosiglitazone (ROSI) and siRNA to inhibit ischemia/hypoxia-induced ACSL4 in vivo and in vitro. The results demonstrated that ACSL4 inhibition before reperfusion protected against ferroptosis and cell death. Further investigation revealed that special protein 1 (Sp1) was a crucial transcription factor that increased ACSL4 transcription by binding to the ACSL4 promoter region. Collectively, this study demonstrates that ferroptosis is closely associated with intestinal I/R injury, and that ACSL4 has a critical role in this lethal process. Sp1 is an important factor in promoting ACSL4 expression. These results suggest a unique and effective mechanistic approach for intestinal I/R injury prevention and treatment.
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8
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Pacheco J, Dominguez L, Bohórquez-Hernández A, Asanov A, Vaca L. A cholesterol-binding domain in STIM1 modulates STIM1-Orai1 physical and functional interactions. Sci Rep 2016; 6:29634. [PMID: 27459950 PMCID: PMC4962086 DOI: 10.1038/srep29634] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/20/2016] [Indexed: 11/09/2022] Open
Abstract
STIM1 and Orai1 are the main components of a widely conserved Calcium influx pathway known as store-operated calcium entry (SOCE). STIM1 is a calcium sensor, which oligomerizes and activates Orai channels when calcium levels drop inside the endoplasmic reticulum (ER). The series of molecular rearrangements that STIM1 undergoes until final activation of Orai1 require the direct exposure of the STIM1 domain known as SOAR (Stim Orai Activating Region). In addition to these complex molecular rearrangements, other constituents like lipids at the plasma membrane, play critical roles orchestrating SOCE. PI(4,5)P2 and enriched cholesterol microdomains have been shown as important signaling platforms that recruit the SOCE machinery in steps previous to Orai1 activation. However, little is known about the molecular role of cholesterol once SOCE is activated. In this study we provide clear evidence that STIM1 has a cholesterol-binding domain located inside the SOAR region and modulates Orai1 channels. We demonstrate a functional association of STIM1 and SOAR to cholesterol, indicating a close proximity of SOAR to the inner layer of the plasma membrane. In contrast, the depletion of cholesterol induces the SOAR detachment from the plasma membrane and enhances its association to Orai1. These results are recapitulated with full length STIM1.
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Affiliation(s)
- Jonathan Pacheco
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, DF 04510, México
| | - Laura Dominguez
- Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México DF 04510, México
| | - A Bohórquez-Hernández
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, DF 04510, México
| | | | - Luis Vaca
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, DF 04510, México
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9
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Abstract
Store Operated Ca(2+) Entry (SOCE), the main Ca(2+) influx mechanism in non-excitable cells, is implicated in the immune response and has been reported to be affected in several pathologies including cancer. The basic molecular constituents of SOCE are Orai, the pore forming unit, and STIM, a multidomain protein with at least two principal functions: one is to sense the Ca(2+) content inside the lumen of the endoplasmic reticulum(ER) and the second is to activate Orai channels upon depletion of the ER. The link between Ca(2+) depletion inside the ER and Ca(2+) influx from extracellular media is through a direct association of STIM and Orai, but for this to occur, both molecules have to interact and form clusters where ER and plasma membrane (PM) are intimately apposed. In recent years a great number of components have been identified as participants in SOCE regulation, including regions of plasma membrane enriched in cholesterol and sphingolipids, the so called lipid rafts, which recruit a complex platform of specialized microdomains, which cells use to regulate spatiotemporal Ca(2+) signals.
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10
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Farnoud AM, Toledo AM, Konopka JB, Del Poeta M, London E. Raft-like membrane domains in pathogenic microorganisms. CURRENT TOPICS IN MEMBRANES 2015; 75:233-68. [PMID: 26015285 DOI: 10.1016/bs.ctm.2015.03.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The lipid bilayer of the plasma membrane is thought to be compartmentalized by the presence of lipid-protein microdomains. In eukaryotic cells, microdomains composed of sterols and sphingolipids, commonly known as lipid rafts, are believed to exist, and reports on the presence of sterol- or protein-mediated microdomains in bacterial cell membranes are also appearing. Despite increasing attention, little is known about microdomains in the plasma membrane of pathogenic microorganisms. This review attempts to provide an overview of the current state of knowledge of lipid rafts in pathogenic fungi and bacteria. The current literature on characterization of microdomains in pathogens is reviewed, and their potential role in growth, pathogenesis, and drug resistance is discussed. Better insight into the structure and function of membrane microdomains in pathogenic microorganisms might lead to a better understanding of their pathogenesis and development of raft-mediated approaches for therapy.
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Affiliation(s)
- Amir M Farnoud
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Alvaro M Toledo
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - James B Konopka
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Maurizio Del Poeta
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
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11
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Gylfason GA, Knútsdóttir E, Ásgeirsson B. Nervonic Acid (24:1n-9) is a Dominant Unsaturated Fatty Acid in the Intestinal Brush Border of Atlantic Cod. Lipid Insights 2012. [DOI: 10.4137/lpi.s10291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Atlantic cod is a coldwater teleost of commercial importance. The intestinal epithelium is a large organ in vertebrates serving an important role in nutrient selection and uptake as well as an immunological barrier. Here, we perform lipid and fatty acid analysis of the plasma membrane from the cod intestinal enterocytes after separation of the brush border membrane and the basolateral membrane fractions. Our results show that both membrane fractions contain an unusually high amount of cholesterol and glycolipids but low levels of glycerophospholipids compared with other reported studies on fish. Sphingomyelin was the dominant lipid in the brush border fraction and was also prominent in the basolateral fraction where phosphatidylcholine was the dominant glycerophospholipid. Furthermore, our results show a distinct difference in fatty acids content, where monounsaturated fatty acids (MUFA) were more abundant than polyunsaturated fatty acid (PUFA). Nervonic acid (24:1n-9) was a prominent fatty acid in the BBM at ~50% of the total MUFA. We hypothesize that the high cholesterol content and the presence of this rare fatty acid may serve to maintain membrane fluidity in the cold environment.
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Affiliation(s)
- Gudjón Andri Gylfason
- Department of Biochemistry, Science Institute, University of Iceland, Reykjavik, Iceland
| | - Erna Knútsdóttir
- Department of Biochemistry, Science Institute, University of Iceland, Reykjavik, Iceland
| | - Bjarni Ásgeirsson
- Department of Biochemistry, Science Institute, University of Iceland, Reykjavik, Iceland
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12
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Ray S, Taylor M, Banerjee T, Tatulian SA, Teter K. Lipid rafts alter the stability and activity of the cholera toxin A1 subunit. J Biol Chem 2012; 287:30395-405. [PMID: 22787142 DOI: 10.1074/jbc.m112.385575] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cholera toxin (CT) travels from the cell surface to the endoplasmic reticulum (ER) as an AB holotoxin. ER-specific conditions then promote the dissociation of the catalytic CTA1 subunit from the rest of the toxin. CTA1 is held in a stable conformation by its assembly in the CT holotoxin, but the dissociated CTA1 subunit is an unstable protein that spontaneously assumes a disordered state at physiological temperature. This unfolding event triggers the ER-to-cytosol translocation of CTA1 through the quality control mechanism of ER-associated degradation. The translocated pool of CTA1 must regain a folded, active structure to modify its G protein target which is located in lipid rafts at the cytoplasmic face of the plasma membrane. Here, we report that lipid rafts place disordered CTA1 in a functional conformation. The hydrophobic C-terminal domain of CTA1 is essential for binding to the plasma membrane and lipid rafts. These interactions inhibit the temperature-induced unfolding of CTA1. Moreover, lipid rafts could promote a gain of structure in the disordered, 37 °C conformation of CTA1. This gain of structure corresponded to a gain of function: whereas CTA1 by itself exhibited minimal in vitro activity at 37 °C, exposure to lipid rafts resulted in substantial toxin activity at 37 °C. In vivo, the disruption of lipid rafts with filipin substantially reduced the activity of cytosolic CTA1. Lipid rafts thus exhibit a chaperone-like function that returns disordered CTA1 to an active state and is required for the optimal in vivo activity of CTA1.
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Affiliation(s)
- Supriyo Ray
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32826, USA
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13
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Gerl MJ, Sampaio JL, Urban S, Kalvodova L, Verbavatz JM, Binnington B, Lindemann D, Lingwood CA, Shevchenko A, Schroeder C, Simons K. Quantitative analysis of the lipidomes of the influenza virus envelope and MDCK cell apical membrane. ACTA ACUST UNITED AC 2012; 196:213-21. [PMID: 22249292 PMCID: PMC3265945 DOI: 10.1083/jcb.201108175] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Analysis of the lipid composition of influenza virus–infected cells provides support for the membrane raft-based biogenesis model. The influenza virus (IFV) acquires its envelope by budding from host cell plasma membranes. Using quantitative shotgun mass spectrometry, we determined the lipidomes of the host Madin–Darby canine kidney cell, its apical membrane, and the IFV budding from it. We found the apical membrane to be enriched in sphingolipids (SPs) and cholesterol, whereas glycerophospholipids were reduced, and storage lipids were depleted compared with the whole-cell membranes. The virus membrane exhibited a further enrichment of SPs and cholesterol compared with the donor membrane at the expense of phosphatidylcholines. Our data are consistent with and extend existing models of membrane raft-based biogenesis of the apical membrane and IFV envelope.
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Affiliation(s)
- Mathias J Gerl
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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14
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Gallala HD, Breiden B, Sandhoff K. Regulation of the NPC2 protein-mediated cholesterol trafficking by membrane lipids. J Neurochem 2011; 116:702-7. [PMID: 21214551 DOI: 10.1111/j.1471-4159.2010.07014.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Recycling and turnover of cell membranes play a critical role in cell metabolism. The internalization of membranes through the different processes of endocytosis, phagocytosis, and autophagy deliver a considerable amount of membranes and lipids to the endosomal and lysosomal system which is tasked with its degradation. Its failure to do so leads to severe fatal neurodegenerative diseases. In order to better understand how membranes are degraded, we have to investigate the complex interactions that take place in this compartment between complex membrane lipids, enzymes and lipid binding and transfer proteins involved. To this end, we developed lipid transfer and fusion assays which allow us to quantify these interactions and assess their specificity. The published results of these investigations are summarized in this article. One of our main conclusions is that we have provided evidence for the hypothesis that acid sphingomyelinase stimulates Niemann pick disease protein type 2-mediated cholesterol export substantially by converting sphingomyelin to ceramide in the inner membranes of late endosomes.
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Affiliation(s)
- Hichem D Gallala
- LIMES, Membrane Biology & Lipid Biochemistry Unit, Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Bonn, Germany
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Glycosphingolipids and Kidney Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 721:121-38. [PMID: 21910086 DOI: 10.1007/978-1-4614-0650-1_8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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16
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17
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Xu YH, Barnes S, Sun Y, Grabowski GA. Multi-system disorders of glycosphingolipid and ganglioside metabolism. J Lipid Res 2010; 51:1643-75. [PMID: 20211931 DOI: 10.1194/jlr.r003996] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Glycosphingolipids (GSLs) and gangliosides are a group of bioactive glycolipids that include cerebrosides, globosides, and gangliosides. These lipids play major roles in signal transduction, cell adhesion, modulating growth factor/hormone receptor, antigen recognition, and protein trafficking. Specific genetic defects in lysosomal hydrolases disrupt normal GSL and ganglioside metabolism leading to their excess accumulation in cellular compartments, particularly in the lysosome, i.e., lysosomal storage diseases (LSDs). The storage diseases of GSLs and gangliosides affect all organ systems, but the central nervous system (CNS) is primarily involved in many. Current treatments can attenuate the visceral disease, but the management of CNS involvement remains an unmet medical need. Early interventions that alter the CNS disease have shown promise in delaying neurologic involvement in several CNS LSDs. Consequently, effective treatment for such devastating inherited diseases requires an understanding of the early developmental and pathological mechanisms of GSL and ganglioside flux (synthesis and degradation) that underlie the CNS diseases. These are the focus of this review.
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Affiliation(s)
- You-Hai Xu
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and the Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229-3039, USA
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18
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Gylfason GA, Knútsdóttir E, Asgeirsson B. Isolation and biochemical characterisation of lipid rafts from Atlantic cod (Gadus morhua) intestinal enterocytes. Comp Biochem Physiol B Biochem Mol Biol 2009; 155:86-95. [PMID: 19854289 DOI: 10.1016/j.cbpb.2009.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 01/21/2023]
Abstract
Lipid rafts are glycosphingolipid/cholesterol-enriched membrane microdomains that have been extensively studied during the past two decades. Our aim was to isolate and perform biochemical characterization of lipid rafts from the intestinal brush border membrane (BBM) of Atlantic cod (Gadus morhua) to confirm their existence in a cold-water species and compare their characteristics with lipid rafts from other species in terms of lipid and protein content. To validate the isolation process, we assayed marker enzymes for subcellular organelles, including alkaline phosphatase (AP) and leucine aminopeptidase (LAP), both well-known marker enzymes for BBM and lipid rafts. All biochemical methods showed enrichment of AP in both the BBM and lipid raft fractions. Proteomic studies were performed by MALDI-TOF mass spectrometry using trypsin digested SDS-PAGE samples. Various proteins were associated with the cod intestinal lipid raft preparation such as aminopeptidase-N, prohibitin, and beta-actin. Lipid analysis with (31)P NMR and thin layer chromatography on BBMs and lipid rafts samples gave higher content of sphingomyelin than previously reported in the BBM and lower content of phosphatidylcholine. Furthermore, sphingomyelin was highly dominant in the lipid rafts together with cholesterol. The existence of lipid rafts containing previously reported lipid raft characteristics from the cod intestine has, therefore, been confirmed in a ray-finned fish for the first time to the best of our knowledge.
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Affiliation(s)
- Gudjón Andri Gylfason
- Department of Biochemistry, Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik, Iceland
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19
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Bibert S, Aebischer D, Desgranges F, Roy S, Schaer D, Kharoubi-Hess S, Horisberger JD, Geering K. A link between FXYD3 (Mat-8)-mediated Na,K-ATPase regulation and differentiation of Caco-2 intestinal epithelial cells. Mol Biol Cell 2008; 20:1132-40. [PMID: 19109419 DOI: 10.1091/mbc.e08-10-0999] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
FXYD3 (Mat-8) proteins are regulators of Na,K-ATPase. In normal tissue, FXYD3 is mainly expressed in stomach and colon, but it is also overexpressed in cancer cells, suggesting a role in tumorogenesis. We show that FXYD3 silencing has no effect on cell proliferation but promotes cell apoptosis and prevents cell differentiation of human colon adenocarcinoma cells (Caco-2), which is reflected by a reduction in alkaline phosphatase and villin expression, a change in several other differentiation markers, and a decrease in transepithelial resistance. Inhibition of cell differentiation in FXYD3-deficient cells is accompanied by an increase in the apparent Na+ and K+ affinities of Na,K-ATPase, reflecting the absence of Na,K-pump regulation by FXYD3. In addition, we observe a decrease in the maximal Na,K-ATPase activity due to a decrease in its turnover number, which correlates with a change in Na,K-ATPase isozyme expression that is characteristic of cancer cells. Overall, our results suggest an important role of FXYD3 in cell differentiation of Caco-2 cells. One possibility is that FXYD3 silencing prevents proper regulation of Na,K-ATPase, which leads to perturbation of cellular Na+ and K+ homeostasis and changes in the expression of Na,K-ATPase isozymes, whose functional properties are incompatible with Caco-2 cell differentiation.
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Affiliation(s)
- Stéphanie Bibert
- Department of Pharmacology, University of Lausanne, 1005 Lausanne, Switzerland
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20
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Regina Todeschini A, Hakomori SI. Functional role of glycosphingolipids and gangliosides in control of cell adhesion, motility, and growth, through glycosynaptic microdomains. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1780:421-33. [PMID: 17991443 PMCID: PMC2312458 DOI: 10.1016/j.bbagen.2007.10.008] [Citation(s) in RCA: 322] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 09/29/2007] [Accepted: 10/12/2007] [Indexed: 01/11/2023]
Abstract
At cell surface microdomains, glycosyl epitopes, carried either by glycosphingolipids, N- or O-linked oligosaccharides, are recognized by carbohydrate-binding proteins or complementary carbohydrates. In both cases, the carbohydrate epitopes may be clustered with specific signal transducers, tetraspanins, adhesion receptors or growth factor receptors. Through this framework, carbohydrates can mediate cell signaling leading to changes in cellular phenotype. Microdomains involved in carbohydrate-dependent cell adhesion inducing cell activation, motility, and growth are termed "glycosynapse". In this review a historical synopsis of glycosphingolipids-enriched microdomains study leading to the concept of glycosynapse is presented. Examples of glycosynapse as signaling unit controlling the tumor cell phenotype are discussed in three contexts: (i) Cell-to-cell adhesion mediated by glycosphingolipids-to-glycosphingolipids interaction between interfacing glycosynaptic domains, through head-to-head (trans) carbohydrate-to-carbohydrate interaction. (ii) Functional role of GM3 complexed with tetraspanin CD9, and interaction of such complex with integrins, or with fibroblast growth factor receptor, to control tumor cell phenotype and its reversion to normal cell phenotype. (iii) Inhibition of integrin-dependent Met kinase activity by GM2/tetraspanin CD82 complex in glycosynaptic microdomain. Data present here suggest that the organizational status of glycosynapse strongly affects cellular phenotype influencing tumor cell malignancy.
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Affiliation(s)
- Adriane Regina Todeschini
- Division of Biomembrane Research, Pacific Northwest Research Institute, University of Washington, Seattle, WA, USA.
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21
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Characterizing the interactions between GPI-anchored alkaline phosphatases and membrane domains by AFM. Pflugers Arch 2007; 456:179-88. [DOI: 10.1007/s00424-007-0409-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 11/12/2007] [Accepted: 11/20/2007] [Indexed: 12/12/2022]
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22
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Zhou Y, Berry CK, Storer PA, Raphael RM. Peroxidation of polyunsaturated phosphatidyl-choline lipids during electroformation. Biomaterials 2007; 28:1298-306. [PMID: 17107709 DOI: 10.1016/j.biomaterials.2006.10.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Accepted: 10/09/2006] [Indexed: 10/23/2022]
Abstract
Giant unilamellar vesicles (GUVs) have been utilized both as model systems to study the physico-chemical properties of biomembranes and as host materials for investigating biological processes in microbioreactors. GUVs are commonly formed by an electroformation technique. However, there is a concern that the electric fields applied during electroformation can peroxidize lipid acyl chains, thereby altering the phospholipid composition and material properties of the synthesized vesicles. Here in this paper, we report the effect of electroformation on the extent of peroxidation of a number of polyunsaturated phosphatidyl-choline lipids (PULs). Specifically, we detected peroxidation byproducts (malonaldehydes and conjugated dienes) of the following lipids utilizing UV/Vis spectroscopy: dilinoleoyl phosphatidyl-choline (DLPC) (di-18:2 PC), dilinolenoyl phosphatidyl-choline (DNPC) (di-18:3 PC), diarachidonoyl phosphatidyl-choline (DAPC) (di-20:4 PC), and didocosaheexaenoyl phosphatidyl-choline (DHA) (di-22:6 PC). The results indicate that PC PULs lipids are prone to peroxidation, with increasing unsaturation levels leading to higher levels of peroxidation byproducts. The levels of peroxidation byproducts of DAPC were found to depend linearly on the strength of the electric field, indicating that the observed effects were due to the applied electric field. Lipid peroxidation can affect a number of important membrane properties, including domain formation and mechanical stability. Thus, alteration of the chemical composition of polyunsaturated lipids (PULs) by the electroformation technique can potentially complicate the interpretation of experimental studies that utilize GUVs composed of PULs.
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Affiliation(s)
- Yong Zhou
- The Department of Biochemistry and Cell Biology, Rice University, Houston, TX, USA
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23
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Sillence DJ. New insights into glycosphingolipid functions--storage, lipid rafts, and translocators. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 262:151-89. [PMID: 17631188 DOI: 10.1016/s0074-7696(07)62003-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glycosphingolipids are key components of eukaryotic cellular membranes. Through their propensity to form lipid rafts, they are important in membrane transport and signaling. At the cell surface, they are required for caveolar-mediated endocytosis, a process required for the action of many glycosphingolipid-binding toxins. Glycosphingolipids also exist intracellularly, on both leaflets of organelle membranes. It is expected that dissecting the mechanisms of cell pathology seen in the glycosphingolipid storage diseases, where lysosomal glycosphingolipid degradation is defective, will reveal their functions. Disrupted cation gradients in Mucolipidosis type IV disease are interlinked with glycosphingolipid storage, defective rab 7 function, and the activation of autophagy. Relationships between drug translocators and glycosphingolipid synthesis are also discussed. Mass spectrometry of cell lines defective in drug transporters reveal clear differences in glycosphingolipid mass and fatty acid composition. The potential roles of glycosphingolipids in lipid raft formation, endocytosis, and cationic gradients are discussed.
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Affiliation(s)
- Dan J Sillence
- Leicester School of Pharmacy, Hawthorne Building, De Montfort University, Leicester, LE1 9BH, United Kingdom
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Hakomori S. Glycosynapses: microdomains controlling carbohydrate-dependent cell adhesion and signaling. AN ACAD BRAS CIENC 2004; 76:553-72. [PMID: 15334254 DOI: 10.1590/s0001-37652004000300010] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The concept of microdomains in plasma membranes was developed over two decades, following observation of polarity of membrane based on clustering of specific membrane components. Microdomains involved in carbohydrate-dependent cell adhesion with concurrent signal transduction that affect cellular phenotype are termed "glycosynapse". Three types of glycosynapse have been distinguished: "type 1" having glycosphingolipid associated with signal transducers (small G-proteins, cSrc, Src family kinases) and proteolipids; "type 2" having O-linked mucin-type glycoprotein associated with Src family kinases; and "type 3" having N-linked integrin receptor complexed with tetraspanin and ganglioside. Different cell types are characterized by presence of specific types of glycosynapse or their combinations, whose adhesion induces signal transduction to either facilitate or inhibit signaling. E.g., signaling through type 3 glycosynapse inhibits cell motility and differentiation. Glycosynapses are distinct from classically-known microdomains termed "caveolae", "caveolar membrane", or more recently "lipid raft", which are not involved in carbohydrate-dependent cell adhesion. Type 1 and type 3 glycosynapses are resistant to cholesterol-binding reagents, whereas structure and function of "caveolar membrane" or "lipid raft" are disrupted by these reagents. Various data indicate a functional role of glycosynapses during differentiation, development, and oncogenic transformation.
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25
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Vistisen B, Høy CE. 13C-labeled 18:2n-6 recovered in brush border membrane phospholipids short time after administration. Nutr Res 2004. [DOI: 10.1016/j.nutres.2003.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Kobayashi M. [The transport mechanism of polycationic compounds across intestinal and renal cell membrane]. YAKUGAKU ZASSHI 2002; 122:607-14. [PMID: 12235852 DOI: 10.1248/yakushi.122.607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This article reviewed the transport mechanism of polycationic compounds across rat intestinal and renal cell membranes. The inside-negative diffusion potential stimulated the initial uptake of dicationic compounds into intestinal brush-border membrane vesicles, and a good correlation was observed between lipophilicity and the amount of diffusion potential-dependent transport of the dications. On the other hand, tri- and tetracationic compounds were not affected by the diffusion potential because of their much lower lipophilicity. The membrane surface potential affected to the transport of polycationic compounds, similar to monocationic compounds. Therefore it appears that the membrane surface potential plays a common role in the transport of mono- and polycationic compounds across cell membranes. On the intestinal basolateral membrane, it was found that there was a Na+/putrescine symporter. This recognized dicationic compounds and transported them from the blood into intestinal cells. This transporter did not recognize spermine and spermidine. Furthermore, we found a novel transport system, a Na+/spermine antiporter, on the rat renal brush-border membrane. This transporter recognized aliphatic polycation, which has more than four amino groups, and actively secreted spermine and trientine into the renal proximal tubules in vitro and in vivo. However, this transporter did not recognize trientine-copper complex. These results are useful for the prediction of the intestinal absorption and renal excretion of polyamine derivatives.
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Affiliation(s)
- Michiya Kobayashi
- Department of Pharmacy, Hokkaido University Hospital, School of Medicine, Hokkaido University, Kita-14-jo, Nishi-5-chome, Kita-ku, Sapporo 060-8648, Japan
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27
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Holthuis JC, Pomorski T, Raggers RJ, Sprong H, Van Meer G. The organizing potential of sphingolipids in intracellular membrane transport. Physiol Rev 2001; 81:1689-723. [PMID: 11581500 DOI: 10.1152/physrev.2001.81.4.1689] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Eukaryotes are characterized by endomembranes that are connected by vesicular transport along secretory and endocytic pathways. The compositional differences between the various cellular membranes are maintained by sorting events, and it has long been believed that sorting is based solely on protein-protein interactions. However, the central sorting station along the secretory pathway is the Golgi apparatus, and this is the site of synthesis of the sphingolipids. Sphingolipids are essential for eukaryotic life, and this review ascribes the sorting power of the Golgi to its capability to act as a distillation apparatus for sphingolipids and cholesterol. As Golgi cisternae mature, ongoing sphingolipid synthesis attracts endoplasmic reticulum-derived cholesterol and drives a fluid-fluid lipid phase separation that segregates sphingolipids and sterols from unsaturated glycerolipids into lateral domains. While sphingolipid domains move forward, unsaturated glycerolipids are retrieved by recycling vesicles budding from the sphingolipid-poor environment. We hypothesize that by this mechanism, the composition of the sphingolipid domains, and the surrounding membrane changes along the cis-trans axis. At the same time the membrane thickens. These features are recognized by a number of membrane proteins that as a consequence of partitioning between domain and environment follow the domains but can enter recycling vesicles at any stage of the pathway. The interplay between protein- and lipid-mediated sorting is discussed.
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Affiliation(s)
- J C Holthuis
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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28
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van Meer G, Holthuis JC. Sphingolipid transport in eukaryotic cells. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1486:145-70. [PMID: 10856719 DOI: 10.1016/s1388-1981(00)00054-8] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Sphingolipids constitute a sizeable fraction of the membrane lipids in all eukaryotes and are indispensable for eukaryotic life. First of all, the involvement of sphingolipids in organizing the lateral domain structure of membranes appears essential for processes like protein sorting and membrane signaling. In addition, recognition events between complex glycosphingolipids and glycoproteins are thought to be required for tissue differentiation in higher eukaryotes and for other specific cell interactions. Finally, upon certain stimuli like stress or receptor activation, sphingolipids give rise to a variety of second messengers with effects on cellular homeostasis. All sphingolipid actions are governed by their local concentration. The intricate control of their intracellular topology by the proteins responsible for their synthesis, hydrolysis and intracellular transport is the topic of this review.
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Affiliation(s)
- G van Meer
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, The Netherlands.
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29
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Hakomori SI. Cell adhesion/recognition and signal transduction through glycosphingolipid microdomain. Glycoconj J 2000; 17:143-51. [PMID: 11201785 DOI: 10.1023/a:1026524820177] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Glycosphingolipids (GSLs) and sphingomyelin in animal cells are clustered and organized as membrane microdomains closely associated with various signal transducer molecules such as cSrc, Src family kinases, small G-proteins (e.g., RhoA, Ras), and focal adhesion kinase. GSL clustering in such microdomains causes adhesion to complementary GSLs on the surface of counterpart cells or presented on plastic surfaces, through carbohydrate-to-carbohydrate interaction. GSL-dependent cell adhesion in microdomain causes activation of the signal transducers, leading to cell phenotypic changes. A retrospective of the development of this concept, and current status of our studies, are presented.
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Affiliation(s)
- S I Hakomori
- Pacific Northwest Research Institute, Seattle, WA 98122-4327, USA.
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30
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31
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Poulsen C, Christensen MS, Høy CE. INCORPORATION OF N-3 POLYUNSATURATED FATTY ACIDS OF MARINE OR VEGETABLE ORIGIN INTO RAT ENTEROCYTE PHOSPHOLIPIDS. Nutr Res 1997. [DOI: 10.1016/s0271-5317(96)00241-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Wild G, Madsen K, Thomson A. Intestinal tight junctions and their importance in health and disease: role of dietary lipids. J Nutr Biochem 1997. [DOI: 10.1016/s0955-2863(96)00151-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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33
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van Helvoort A, van Meer G. Intracellular lipid heterogeneity caused by topology of synthesis and specificity in transport. Example: sphingolipids. FEBS Lett 1995; 369:18-21. [PMID: 7641876 DOI: 10.1016/0014-5793(95)00616-h] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The differences in lipid composition between intracellular membranes cannot be adequately explained by local synthesis and degradation. Especially in the case of sphingolipids, which are synthesized in the Golgi complex but enriched on the cell surface and in endocytotic organelles, there is evidence for a cellular machinery that preferentially shuttles these lipids in vesicles to the cell surface. The machinery appears to involve the formation of domains of sphingolipid and cholesterol in the lumenal leaflet of Golgi membranes. Several pieces of evidence suggest that the selective anterograde transport of plasma membrane proteins may be mechanistically related to the sphingolipid domains.
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Affiliation(s)
- A van Helvoort
- Department of Cell Biology, Faculty of Medicine, Universiteit Utrecht, The Netherlands
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34
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Muriana FJ, Ruiz-Gutierrez V, Blaya JA, Bolufer J. Phospholipid fatty acid composition of hepatopancreatic brush-border membrane vesicles from the prawn Penaeus japonicus. Biochimie 1995; 77:190-3. [PMID: 7647111 DOI: 10.1016/0300-9084(96)88124-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Brush-border membrane vesicles (BBMV) were isolated from prawn hepatopancreas as we previously described (Muriana et al (1993) J Biochem 113, 625-629). The characterization of hepatopancreatic BBMV (hBBMV) by monitoring the activity of marker enzymes indicated a relatively pure apical membrane preparation reduced in basolateral contamination. Phospholipid composition of hBBMV was examined by the Iatroscan TLC/FID technique, whereas the fatty acid profile of phospholipids was examined by capillary gas chromatography. Phosphatidylcholine and phosphatidylethanolamine are the principal phospholipids of these membranes. The major fatty acids of phospholipids are palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), oleic (18:1n-9), eicosapentaenoic (20:5n-3) and docosapentaenoic (22:5n-3) acids. Individual phospholipids are characterized by distinct fatty acid compositions, but display a similar ratio of unsaturated-to-saturated fatty acids and a similar unsaturation index.
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Affiliation(s)
- F J Muriana
- Instituto de la Grasa (CSIC), Sevilla, Spain
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35
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Schulthess G, Hauser H. A unique feature of lipid dynamics in small intestinal brush border membrane. Mol Membr Biol 1995; 12:105-12. [PMID: 7767368 DOI: 10.3109/09687689509038504] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The lipid composition of the brush border membrane (BBM) or apical plasma membrane of enterocytes is characterized by a remarkably high glycosphingolipid content (glycosphingolipid: phospholipid:neutral lipid mole ratio of about 1:1:1). A manifestation of the high glycolipid content of the BBM is the lipid fluidity which is low compared to other mammalian plasma membranes and related to it a steep flexibility gradient: hydrocarbon chain segments close to the lipid-water interface have quasi-crystalline packing while hydrocarbon chain segments close to the centre of the lipid bilayer behave like a fluid. An important function of the BBM is the absorption of dietary lipids. The absorption of cholesterol from bile salt micelles has been shown to be protein-mediated. The integral membrane protein responsible for this activity has features similar to non-specific lipid transfer proteins. Another remarkable property of the BBM is described here: phospholipids are exchanged between the lipid bilayer of the BBM and the lipid bilayers of small unilamellar egg phosphatidylcholine (PC) vesicles. In the course of this probably 1:1 exchange, endogenous BBM phospholipids move out of the BBM and the lipid loss is compensated by the insertion of exogenous PC from the small unilamellar vesicles. This exchange activity is probably due to the same protein(s) responsible for lipid absorption in this membrane or at least related to the absorptive capacity of the BBM. The unique feature of small intestinal BBM is that the on- and off-rate of certain lipids is remarkably high: the underlying structure of this activity is still unknown.
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Affiliation(s)
- G Schulthess
- Laboratorium für Biochemie, Eidgenössische Technische Hochschule Zürich, Switzerland
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36
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Alcorn CJ, Simpson RJ, Leahy D, Peters TJ. In vitro studies of intestinal drug absorption. Determination of partition and distribution coefficients with brush border membrane vesicles. Biochem Pharmacol 1991; 42:2259-64. [PMID: 1764112 DOI: 10.1016/0006-2952(91)90228-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Brush border membrane vesicles (BBMV) were isolated from rat small intestine and characterized in terms of relative enrichment of specific organelle marker enzymes (20-fold enrichment; 20% yield), contamination by other subcellular organelles (less than 1%) and functional integrity (Na(+)-dependent glucose uptake). Using these vesicles, techniques were developed for the determination of partition and distribution coefficients for the model solutes, nitrobenzene, toluene and benzoic acid. No gender, age or regional variation along the small intestine in partition coefficient (log P) values was detected. There was no temperature (10-40 degrees) or pH (4.5-8.0) dependence in partition coefficients of nitrobenzene and toluene. Fair agreement was obtained for log P and log D values for these two solutes determined with BBMV and those reported with octanol and propylene glycol dipelargonate. Selective removal of proteins, both ecto-brush border and micro-villus core proteins, did not alter the partition coefficients of the three model solutes. In contrast, depletion of the BBMV of non-esterified fatty acids significantly decreased the partition coefficients. Liposomes prepared from BBMV lipid extracts were also used for partition coefficient determinations and gave similar values to intact BBMV; addition of increasing amounts of cholesterol to the lipid extract caused small increases in the partition coefficients of the model solutes in the liposomes. It was concluded that the partition coefficients of the BBMV were related to the lipid and not to the protein composition of the vesicles. The method offers a rapid and reliable means of measuring the partition coefficient of non-protein bound drugs and nutrients in isolated intestinal BBMV and should assist in the subsequent modelling and prediction of intestinal absorption in vivo.
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Affiliation(s)
- C J Alcorn
- Department of Clinical Biochemistry, King's College School of Medicine and Dentistry, London, U.K
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37
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Beaudoin AR, Grondin G. Shedding of vesicular material from the cell surface of eukaryotic cells: different cellular phenomena. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1071:203-19. [PMID: 1958687 DOI: 10.1016/0304-4157(91)90014-n] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- A R Beaudoin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Canada
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38
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Proulx P. Structure-function relationships in intestinal brush border membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1071:255-71. [PMID: 1958689 DOI: 10.1016/0304-4157(91)90016-p] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- P Proulx
- Department of Biochemistry, Faculty of Medicine, University of Ottawa, Canada
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39
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van Genderen IL, van Meer G, Slot JW, Geuze HJ, Voorhout WF. Subcellular localization of Forssman glycolipid in epithelial MDCK cells by immuno-electronmicroscopy after freeze-substitution. J Biophys Biochem Cytol 1991; 115:1009-19. [PMID: 1955453 PMCID: PMC2289941 DOI: 10.1083/jcb.115.4.1009] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Forssman antigen, a neutral glycosphingolipid carrying five monosaccharides, was localized in epithelial MDCK cells by the immunogold technique. Labeling with a well defined mAb and protein A-gold after freeze-substitution and low temperature embedding in Lowicryl HM20 of aldehyde-fixed and cryoprotected cells, resulted in high levels of specific labeling and excellent retention of cellular ultrastructure compared to ultra-thin cryosections. No Forssman glycolipid was lost from the cells during freeze-substitution as measured by radio-immunostaining of lipid extracts. Redistribution of the glycolipid between membranes did not occur. Forssman glycolipid, abundantly expressed on the surface of MDCK II cells, did not move to neighboring cell surfaces in cocultures with Forssman negative MDCK I cells, even though they were connected by tight junctions. The labeling density on the apical plasma membrane was 1.4-1.6 times higher than basolateral. Roughly two-thirds of the gold particles were found intracellularly. The Golgi complex was labeled for Forssman as were endosomes, identified by endocytosed albumin-gold, and lysosomes, defined by double labeling for cathepsin D. In most cases, the nuclear envelope was Forssman positive, but the labeling density was 10-fold less than on the plasma membrane. Mitochondria and peroxisomes, the latter identified by catalase, remained free of label, consistent with the notion that they do not receive transport vesicles carrying glycosphingolipids. The present method of lipid immunolabeling holds great potential for the localization of other antigenic lipids.
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Affiliation(s)
- I L van Genderen
- Department of Cell Biology, Medical School, University of Utrecht, The Netherlands
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40
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Affiliation(s)
- R W Compans
- Department of Microbiology, University of Alabama, Birmingham 35294
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41
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van 't Hof W, van Meer G. Generation of lipid polarity in intestinal epithelial (Caco-2) cells: sphingolipid synthesis in the Golgi complex and sorting before vesicular traffic to the plasma membrane. J Cell Biol 1990; 111:977-86. [PMID: 2391372 PMCID: PMC2116282 DOI: 10.1083/jcb.111.3.977] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Generation of intestinal epithelial lipid polarity was studied in Caco-2 cells. Confluent monolayers on filters incorporated the exchangeable lipid N-6-NBD-aminocaproyl-sphingosine (C6-NBD-ceramide) from liposomes. The fluorescent ceramide was converted equally to C6-NBD-glucosylceramide and C6-NBD-sphingomyelin, analogues of lipids enriched on the apical and basolateral surface, respectively, of intestinal cells in vivo. Below 16 degrees C, where vesicular traffic is essentially blocked, each fluorescent product accumulated in the Golgi area. At 37 degrees C, 50% had been transported to the cell surface within 0.5 h, as measured by selective extraction of the fluorescent lipids onto BSA in the medium ("back-exchange") at 10 degrees C. Transport to the two surfaces could be assayed separately, as a diffusion barrier existed for both NBD-lipids and BSA. C6-NBD-glucosylceramide was enriched twofold apically, whereas C6-NBD-sphingomyelin was equally distributed over both domains. Polarities did not decrease when 37 degrees C incubations were carried out in the presence of increasing BSA concentrations to trap the fluorescent lipids immediately after their arrival at the cell surface. Within 10 min from the start of synthesis, both products displayed their typical surface polarity. Lipid transcytosis displayed a half time of hours. In conclusion, newly synthesized sphingolipids in Caco-2 cells are sorted before reaching the cell surface. Transcytosis is not required for generating the in vivo lipid polarity.
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Affiliation(s)
- W van 't Hof
- Department of Cell Biology, Medical School, University of Utrecht, The Netherlands
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42
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Saitoh H, Ebina M, Fukuda S, Iseki K, Miyazaki K, Arita T. Involvement of sialic acid in high-affinity binding of quaternary ammonium compounds by brush border membrane from rat intestine. J Pharm Pharmacol 1989; 41:459-63. [PMID: 2570850 DOI: 10.1111/j.2042-7158.1989.tb06500.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
As one approach to clarify the absorption mechanisms of quaternary ammonium compounds (QACs), their binding characteristics have been studied using brush border membrane vesicles isolated from rat small intestine and liposomes composed of phospholipid and GM3 ganglioside. The binding of propantheline was significantly decreased when the vesicles were pretreated with neuraminidase. Propantheline and methochlorpromazine bound to the liposomes, the binding for the latter drug being significantly greater than that for propantheline. When GM3, isolated from rat small intestine, was incorporated into the liposomes their binding capacity for both drugs increased significantly. It is suggested that the binding of QACs to the lipid layer and sialic acid play a role in the high binding of drugs to the intestinal brush border membrane. Furthermore, a sensitive and reproducible high-performance liquid chromatographic method for sialic acid has been developed.
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Affiliation(s)
- H Saitoh
- Department of Pharmacy, Hokkaido University Hospital, School of Medicine, Hokkaido University, Sapporo, Japan
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43
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Simpson RJ, Venkatesan S, Peters TJ. Brush border membrane non-esterified fatty acids. Physiological levels and significance for mucosal iron uptake in mouse proximal intestine. Cell Biochem Funct 1989; 7:165-71. [PMID: 2791212 DOI: 10.1002/cbf.290070303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Brush border membrane vesicles prepared using divalent cation precipitation methods can contain unphysiological levels of non-esterified fatty acids. Fatty acid production from endogenous lipid during brush border membrane vesicle preparation is effectively prevented by the lipase inhibitor diethyl 4-nitrophenylphosphate plus cooling. Vesicles prepared using this procedure have variable levels of non-esterified fatty acids (range 22-193 nmol mg-1 protein). Changes in non-esterified fatty acid levels in brush border membrane vesicles parallel Fe uptake by vesicles from Fe/ascorbate solutions. Brush border membrane vesicle fatty acids appear to be derived from the diet but hypoxic mice are able to maintain high brush border membrane non-esterified fatty acid levels despite reduced dietary intake. Non-esterified fatty acids in brush border membrane may thus provide a physiological mechanism of mucosal Fe uptake.
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Affiliation(s)
- R J Simpson
- Department of Clinical Biochemistry, King's College School of Medicine and Dentistry, London, U.K
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44
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Larson G, Falk P, Howard R, Banwell JG. Intestinal sphingolipid excretion associated with feeding of phytohemagglutinin lectin (Phaseolus vulgaris) to germ-free and conventional rats. Glycoconj J 1989; 6:539-50. [PMID: 2535498 DOI: 10.1007/bf01053776] [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: 01/01/2023]
Abstract
Intestinal sphingolipids of feces of germ-free and conventional rats were analyzed during the pair feeding of a complete defined diet containing phytohemagglutinin lectin (PHA) from red kidney beans (Phaseolus vulgaris) as 1% dietary protein in comparison to casein fed controls. Phytohemagglutinin in the diet increased the total fecal excretion of sphingomyelins (18-fold for germ-free and 20-fold for conventional rats), of non-acid glycosphingolipids (3.5-fold for germ-free and 9-fold for conventional rats) and also of the gangliosides (2.5-fold) for the germ-free rats compared to controls. For germ-free rats the increase of non-acid glycolipids was ascribed to an effect of the lectin strictly on the small intestinal mucosa, while for conventional rats an effect was seen also on the large intestinal mucosa. Increase of fecal gangliosides of germ-free rats was due mainly to an increased excretion of N-acetylneuraminosyl-lactosylceramide, a ganglioside species restricted to epithelial cells of duodenum, of upper jejunum and of large intestines. The effects on glycolipid excretion observed in germ-free rats and the rather similar effects seen in conventional animals suggested that the influence of dietary PHA was due directly to effects elicited by PHA binding to the enterocyte brush border membrane and not to secondary effects induced by increase in the luminal microflora.
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Affiliation(s)
- G Larson
- Department of Clinical Chemistry, Gothenburg University, Sahlgren's Hospital, Sweden
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45
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Affiliation(s)
- K Simons
- European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany
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46
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Venien C, Le Grimellec C. Phospholipid asymmetry in renal brush-border membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 942:159-68. [PMID: 3164218 DOI: 10.1016/0005-2736(88)90285-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The topological distribution of phospholipids between the inside and the outside of rabbit kidney brush-border membranes has been investigated by incubating membrane vesicles with sphingomyelinase, phospholipases A2 from bee venom and hog pancreas, phospholipases C and D, and trinitrobenzene sulfonate. Orientation and integrity of vesicles upon phospholipase treatment was determined by using two monoclonal antibodies recognizing an extracytoplasmic and a cytoplasmic domain, respectively, of the neutral endopeptidase (EC 3.4.24.11). It is shown that the transbilayer distribution of phospholipids is highly asymmetrical in kidney brush-border membranes: sphingomyelin accounted for 75% of the phospholipids present in the external leaflet, whereas phosphatidylethanolamine and phosphatidylserine plus phosphatidylinositol were found to comprise the majority of the inner layer of the membrane.
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Affiliation(s)
- C Venien
- INSERM U.251, Département de Physiologie, Faculté de Medecine Xavier-Bichat, Paris, France
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47
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De Jonge H, Schmeeda H, Shaltiel S. Orientation of the brush-border membranal proteinase which specifically splits the catalytic subunit of cAMP-dependent protein kinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 169:503-9. [PMID: 2826148 DOI: 10.1111/j.1432-1033.1987.tb13638.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The active site of the rat intestinal brush-border membranal proteinase [Alhanaty E. and Shaltiel S. (1979) Biochem. Biophys. Res. Commun. 89, 323-332], which splits the catalytic subunit (C) of cAMP-dependent protein kinase with a remarkable specificity [Alhanaty E., Tauber-Finkelstein, M., Schmeeda, H. and Shaltiel, S. (1985) Curr. Topics Cell. Regul. 27, 267-277], is shown to face predominantly the cell exterior; vesicles prepared from these brush-borders (mostly sealed and right-side-out) fully express the proteinase activity as judged by the fact that there is no increase in activity upon rupture or solubilization of the vesicles. Although the brush-border vesicles contain a cAMP-dependent protein kinase, this membrane-bound kinase is not likely to be the physiological target of the proteinase, since it appears to have an intracellular orientation and, at least in the vesicles, to be inaccessible to the proteinase. It is, therefore, suggested that the physiological substrate of the proteinase might be either an extracellular cAMP-dependent protein kinase, which is lost (e.g. removed, inactivated or degraded) in the course of vesicle isolation, or a kinase domain in one of the family of proteins recently shown to have a considerable structural and conformational homology with C. Alternatively the physiological site of action of this kinase-splitting proteinase might be an intracellular organelle to which it is translocated by endocytosis.
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Affiliation(s)
- H De Jonge
- Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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48
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Nichols GE, Shiraishi T, Allietta M, Tillack TW, Young WW. Polarity of the Forssman glycolipid in MDCK epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 930:154-66. [PMID: 3040119 DOI: 10.1016/0167-4889(87)90027-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To determine whether epithelial plasma membrane glycolipids are polarized in a manner analogous to membrane proteins, MDCK cells grown on permeable filters were analyzed for the expression of Forssman ceramide pentasaccharide, the major neutral glycolipid in these cells. In contrast to a recent report which described exclusive apical localization of the Forssman glycolipid (Hansson, G.C., Simons, K. and Van Meer, G. (1986) EMBO J. 5, 483-489), immunofluorescence and immunoelectron microscopic staining revealed the Forssman glycolipid on both the apical and basolateral surfaces of polarized cells. Immunoblots indicated that the Forssman antigen was detectable only on glycolipids and not on proteins. Analysis of metabolically labeled glycolipids released into the apical and basal culture medium, either as shed membrane vesicles or in budding viruses, also demonstrated the presence of the Forssman glycolipid on both apical and basolateral membranes of polarized cells. Quantitation of the released glycolipid indicated that the Forssman glycolipid was concentrated in the apical membrane. These results are consistent with previous reports which described quantitative enrichment of glycolipids in the apical domain of several epithelia.
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49
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Trier JS, Allan CH, Marcial MA, Madara JL. Structural features of the apical and tubulovesicular membranes of rodent small intestinal tuft cells. Anat Rec (Hoboken) 1987; 219:69-77. [PMID: 3688463 DOI: 10.1002/ar.1092190112] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Tuft cells are present in most columnar epithelia derived from endoderm including the small intestine. They are characterized by long, wide apical microvilli and an extensively developed cytoplasmic tubulovesicular system. We examined in detail the structural features of the apical plasma membrane of small intestinal tuft cells from adult guinea pigs, rats, and adult and suckling mice with freeze-fracture and conventional transmission electron microscopy methods and utilized cationized ferritin and horseradish peroxidase as tracers to determine whether tuft cells endocytose macromolecules. The microvillus membrane of intestinal tuft cells has few P-face intramembrane particles, displays little alkaline phosphatase activity, and is highly enriched in cholesterol. Tuft cell tight junctions resemble those of absorptive cells in strand count and strand-to-strand crosslinks but, unlike those of absorptive cells, they display many abluminal free-ending strands. Tuft cells of adult and suckling mouse intestine show no evidence of internalization of cationized ferritin or, in suckling mice, uptake of horseradish peroxidase. We conclude that the microvillus membrane of small intestinal tuft cells is protein-poor but cholesterol-rich and that small intestinal tuft cells do not endocytose macromolecules in bulk from the intestinal lumen.
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Affiliation(s)
- J S Trier
- Department of Medicine, Brigham and Women's Hospital, Boston, MA
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50
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Mizuno M, Yoshino H, Hashida M, Sezaki H. Decreased transport of D-glucose and L-alanine across brush-border membrane vesicles from small intestine of rats treated with mitomycin C. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 902:93-100. [PMID: 3111535 DOI: 10.1016/0005-2736(87)90139-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To elucidate the mechanisms underlying the dysfunctions of intestinal absorption induced by antitumor drugs, the effect of pretreatment with mitomycin C on sodium gradient-dependent D-glucose and L-alanine transports was studied in rat brush-border membrane vesicles. 24, 48, 96, or 120 h following a single intravenous injection of mitomycin C, brush-border membrane vesicles were prepared from rat small-intestines. The uptake of D-glucose and L-alanine was shown to be Na+ gradient-dependent even in the case of vesicles obtained from mitomycin C-treated rats, but uptake rates measured at 15 s and magnitude of overshooting effect in uptake of both solutes were decreased in vesicles maximally from 48 h mitomycin C-treated rats. The rate of D-glucose uptake calculated at 15 s recovered to the control level in vesicles prepared at 96 h and 120 h after mitomycin C-treatment, indicating that the effect of mitomycin C on Na+ gradient-dependent D-glucose transport would be fully reversible. Tracer exchange experiments under Na+ and D-glucose equilibrated conditions indicated that the Na+/D-glucose transporters were similarly operative in the vesicles from control and 48 h mitomycin C-treated rats. Rates of 22Na+ uptake measured at 15 s in vesicles from 48 h mitomycin C-treated rats, however, were increased. The increased permeability to Na+ might bring about a more rapid dissipation of the Na+ gradient in these vesicles and this would secondarily cause the decrease in Na+-dependent D-glucose uptake in vesicles from mitomycin C-treated rats.
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