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Zietek T, Boomgaarden WAD, Rath E. Drug Screening, Oral Bioavailability and Regulatory Aspects: A Need for Human Organoids. Pharmaceutics 2021; 13:1280. [PMID: 34452240 PMCID: PMC8399541 DOI: 10.3390/pharmaceutics13081280] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/12/2021] [Accepted: 08/14/2021] [Indexed: 12/31/2022] Open
Abstract
The intestinal epithelium critically contributes to oral bioavailability of drugs by constituting an important site for drug absorption and metabolism. In particular, intestinal epithelial cells (IEC) actively serve as gatekeepers of drug and nutrient availability. IECs' transport processes and metabolism are interrelated to the whole-body metabolic state and represent potential points of origin as well as therapeutic targets for a variety of diseases. Human intestinal organoids represent a superior model of the intestinal epithelium, overcoming limitations of currently used in vitro models. Caco-2 cells or rodent explant models face drawbacks such as their cancer and non-human origin, respectively, but are commonly used to study intestinal nutrient absorption, enterocyte metabolism and oral drug bioavailability, despite poorly correlative data. In contrast, intestinal organoids allow investigating distinct aspects of bioavailability including spatial resolution of transport, inter-individual differences and high-throughput screenings. As several countries have already developed strategic roadmaps to phase out animal experiments for regulatory purposes, intestinal organoid culture and organ-on-a-chip technology in combination with in silico approaches are roads to go in the preclinical and regulatory setup and will aid implementing the 3Rs (reduction, refinement and replacement) principle in basic science.
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Affiliation(s)
- Tamara Zietek
- Doctors against Animal Experiments, 51143 Köln, Germany
| | | | - Eva Rath
- Chair of Nutrition and Immunology, Technische Universität München, 85354 Freising, Germany
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2
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Prabhala BK, Rahman M, Nour-Eldin HH, Jørgensen FS, Mirza O. PTR2/POT/NPF transporters: what makes them tick? ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 123:219-240. [PMID: 33485485 DOI: 10.1016/bs.apcsb.2020.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PTR2/POT/NPF are a family of primarily proton coupled transporters that belong to the major facilitator super family and are found across most kingdoms of life. They are involved in uptake of nutrients, hormones, ions and several orally administered drug molecules. A wealth of structural and functional data is available for this family; the similarity between the protein structural features have been discussed and investigated in detail on several occasions, however there are no reports on the unification of substrate information. In order to fill this gap, we have collected information about substrates across the entire PTR2/POT/NPF family in order to provide key insights into what makes a molecule a substrate and whether there are common features among confirmed substrates. This review will be of particular interest for researchers in the field trying to probe the mechanisms responsible for the different selectivity of these transporters at a molecular resolution, and to design novel substrates.
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Affiliation(s)
- Bala K Prabhala
- Institute of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Moazur Rahman
- School of Biological Sciences, University of the Punjab, Lahore, Punjab, Pakistan; Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan
| | - Hussam H Nour-Eldin
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Flemming Steen Jørgensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Osman Mirza
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Diabetes downregulates peptide transporter 1 in the rat jejunum: possible involvement of cholate-induced FXR activation. Acta Pharmacol Sin 2020; 41:1465-1475. [PMID: 32341465 DOI: 10.1038/s41401-020-0408-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/24/2020] [Indexed: 12/31/2022] Open
Abstract
Peptide transporter 1 (PepT1), highly expressed on the apical membrane of enterocytes, is involved in energy balance and mediates intestinal absorption of peptidomimetic drugs. In this study, we investigated whether and how diabetes affected the function and expression of intestinal PepT1. Diabetes was induced in rats by combination of high-fat diet and low dose streptozocin injection. Pharmacokinetics study demonstrated that diabetes significantly decreased plasma exposures of cephalexin and acyclovir following oral administration of cephalexin and valacyclovir, respectively. Single-pass intestinal perfusion analysis showed that diabetes remarkably decreased cephalexin absorption, which was associated with decreased expression of intestinal PepT1 protein. We assessed the levels of bile acids in intestine of diabetic rats, and found that diabetic rats exhibited significantly higher levels of chenodeoxycholic acid (CDCA), cholic acid (CA) and glycocholic acid (GCA), and lower levels of lithocholic acid (LCA) and hyodeoxycholic acid (HDCA) than control rats; intestinal deoxycholic acid (DCA) levels were unaltered. In Caco-2 cells, the 6 bile acids remarkably decreased expression of PepT1 protein with CDCA causing the strongest inhibition, whereas TNF-α, LPS and insulin little affected expression of PepT1 protein; short-chain fatty acids induced rather than decreased expression of PepT1 protein. Farnesoid X receptor (FXR) inhibitor glycine-β-muricholic acid or FXR knockdown reversed the downregulation of PepT1 expression by CDCA and GW4064 (another FXR agonist). In diabetic rats, the expression of intestinal FXR protein was markedly increased. Oral administration of CDCA (90, 180 mg·kg-1·d-1, for 3 weeks) dose-dependently decreased the expression and function of intestinal PepT1 in rats. In conclusion, diabetes impairs the expression and function of intestinal PepT1 partly via CDCA-mediated FXR activation.
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Kaji I, Roland JT, Watanabe M, Engevik AC, Goldstein AE, Hodges CA, Goldenring JR. Lysophosphatidic Acid Increases Maturation of Brush Borders and SGLT1 Activity in MYO5B-deficient Mice, a Model of Microvillus Inclusion Disease. Gastroenterology 2020; 159:1390-1405.e20. [PMID: 32534933 PMCID: PMC8240502 DOI: 10.1053/j.gastro.2020.06.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 05/29/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIM Myosin VB (MYO5B) is an essential trafficking protein for membrane recycling in gastrointestinal epithelial cells. The inactivating mutations of MYO5B cause the congenital diarrheal disease, microvillus inclusion disease (MVID). MYO5B deficiency in mice causes mislocalization of SGLT1 and NHE3, but retained apical function of CFTR, resulting in malabsorption and secretory diarrhea. Activation of lysophosphatidic acid (LPA) receptors can improve diarrhea, but the effect of LPA on MVID symptoms is unclear. We investigated whether LPA administration can reduce the epithelial deficits in MYO5B-knockout mice. METHODS Studies were conducted with tamoxifen-induced, intestine-specific knockout of MYO5B (VilCreERT2;Myo5bflox/flox) and littermate controls. Mice were given LPA, an LPAR2 agonist (GRI977143), or vehicle for 4 days after a single injection of tamoxifen. Apical SGLT1 and CFTR activities were measured in Üssing chambers. Intestinal tissues were collected, and localization of membrane transporters was evaluated by immunofluorescence analysis in tissue sections and enteroids. RNA sequencing and enrichment analysis were performed with isolated jejunal epithelial cells. RESULTS Daily administration of LPA reduced villus blunting, frequency of multivesicular bodies, and levels of cathepsins in intestinal tissues of MYO5B-knockout mice compared with vehicle administration. LPA partially restored the brush border height and the localization of SGLT1 and NHE3 in small intestine of MYO5B-knockout mice and enteroids. The SGLT1-dependent short-circuit current was increased and abnormal CFTR activities were decreased in jejunum from MYO5B-knockout mice given LPA compared with vehicle. CONCLUSIONS LPA may regulate a MYO5B-independent trafficking mechanism and brush border maturation, and therefore be developed for treatment of MVID.
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Affiliation(s)
- Izumi Kaji
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee; Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, Tennessee.
| | - Joseph T. Roland
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | | | - Amy C. Engevik
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | - Anna E. Goldstein
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | - Craig A. Hodges
- Cystic Fibrosis Mouse Models Resource Center, Case Western Reserve University, Cleveland, OH
| | - James R. Goldenring
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan,Cell and Developmental Biology, Vanderbilt University School of Medicine, Sapporo, Japan,Nashville Veterans Affairs Medical Center, Nashville TN
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5
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McCauley HA, Matthis AL, Enriquez JR, Nichol JT, Sanchez JG, Stone WJ, Sundaram N, Helmrath MA, Montrose MH, Aihara E, Wells JM. Enteroendocrine cells couple nutrient sensing to nutrient absorption by regulating ion transport. Nat Commun 2020; 11:4791. [PMID: 32963229 PMCID: PMC7508945 DOI: 10.1038/s41467-020-18536-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 08/25/2020] [Indexed: 12/13/2022] Open
Abstract
The ability to absorb ingested nutrients is an essential function of all metazoans and utilizes a wide array of nutrient transporters found on the absorptive enterocytes of the small intestine. A unique population of patients has previously been identified with severe congenital malabsorptive diarrhea upon ingestion of any enteral nutrition. The intestines of these patients are macroscopically normal, but lack enteroendocrine cells (EECs), suggesting an essential role for this rare population of nutrient-sensing cells in regulating macronutrient absorption. Here, we use human and mouse models of EEC deficiency to identify an unappreciated role for the EEC hormone peptide YY in regulating ion-coupled absorption of glucose and dipeptides. We find that peptide YY is required in the small intestine to maintain normal electrophysiology in the presence of vasoactive intestinal polypeptide, a potent stimulator of ion secretion classically produced by enteric neurons. Administration of peptide YY to EEC-deficient mice restores normal electrophysiology, improves glucose and peptide absorption, diminishes diarrhea and rescues postnatal survival. These data suggest that peptide YY is a key regulator of macronutrient absorption in the small intestine and may be a viable therapeutic option to treat patients with electrolyte imbalance and nutrient malabsorption. Enteroendocrine cells (EECs) are specialized gastrointestinal cells that have a role in nutrient sensing and hormone secretion. Here the authors show that peptide YY from EECs regulates nutrient absorption in intestinal organoids.
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Affiliation(s)
- Heather A McCauley
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Andrea L Matthis
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA
| | - Jacob R Enriquez
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Jonah T Nichol
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - J Guillermo Sanchez
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - William J Stone
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Nambirajan Sundaram
- Division of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Michael A Helmrath
- Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.,Division of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Marshall H Montrose
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA
| | - Eitaro Aihara
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA
| | - James M Wells
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA. .,Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA. .,Division of Endocrinology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.
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6
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Zietek T, Giesbertz P, Ewers M, Reichart F, Weinmüller M, Urbauer E, Haller D, Demir IE, Ceyhan GO, Kessler H, Rath E. Organoids to Study Intestinal Nutrient Transport, Drug Uptake and Metabolism - Update to the Human Model and Expansion of Applications. Front Bioeng Biotechnol 2020; 8:577656. [PMID: 33015026 PMCID: PMC7516017 DOI: 10.3389/fbioe.2020.577656] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/19/2020] [Indexed: 12/22/2022] Open
Abstract
Intestinal transport and sensing processes and their interconnection to metabolism are relevant to pathologies such as malabsorption syndromes, inflammatory diseases, obesity and type 2 diabetes. Constituting a highly selective barrier, intestinal epithelial cells absorb, metabolize, and release nutrients into the circulation, hence serving as gatekeeper of nutrient availability and metabolic health for the whole organism. Next to nutrient transport and sensing functions, intestinal transporters including peptide transporter 1 (PEPT1) are involved in the absorption of drugs and prodrugs, including certain inhibitors of angiotensin-converting enzyme, protease inhibitors, antivirals, and peptidomimetics like β-lactam antibiotics. Here, we verify the applicability of 3D organoids for in vitro investigation of intestinal biochemical processes related to transport and metabolism of nutrients and drugs. Establishing a variety of methodologies including illustration of transporter-mediated nutrient and drug uptake and metabolomics approaches, we highlight intestinal organoids as robust and reliable tool in this field of research. Currently used in vitro models to study intestinal nutrient absorption, drug transport and enterocyte metabolism, such as Caco-2 cells or rodent explant models are of limited value due to their cancer and non-human origin, respectively. Particularly species differences result in poorly correlative data and findings obtained in these models cannot be extrapolated reliably to humans, as indicated by high failure rates in drug development pipelines. In contrast, human intestinal organoids represent a superior model of the intestinal epithelium and might help to implement the 3Rs (Reduction, Refinement and Replacement) principle in basic science as well as the preclinical and regulatory setup.
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Affiliation(s)
- Tamara Zietek
- Chair of Nutritional Physiology, Technische Universität München, Munich, Germany
| | - Pieter Giesbertz
- Chair of Nutritional Physiology, Technische Universität München, Munich, Germany
| | - Maren Ewers
- Pediatric Nutritional Medicine, Klinikum Rechts der Isar, Else Kröner-Fresenius-Zentrum für Ernährungsmedizin, Technische Universität München, Munich, Germany
| | - Florian Reichart
- Institute for Advanced Study, Department of Chemistry and Center for Integrated Protein Science (CIPSM), Technische Universität München, Garching, Germany
| | - Michael Weinmüller
- Institute for Advanced Study, Department of Chemistry and Center for Integrated Protein Science (CIPSM), Technische Universität München, Garching, Germany
| | - Elisabeth Urbauer
- Chair of Nutrition and Immunology, Technische Universität München, Munich, Germany
| | - Dirk Haller
- Chair of Nutrition and Immunology, Technische Universität München, Munich, Germany.,ZIEL Institute for Food and Health, Technische Universität München, Munich, Germany
| | - Ihsan Ekin Demir
- Department of Surgery, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,Department of General Surgery, HPB-Unit, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey.,German Cancer Consortium (DKTK), Munich, Germany.,CRC 1321 Modeling and Targeting Pancreatic Cancer, Klinikum rechts der Isar, School of Medicine, Technische Universität München, Munich, Germany
| | - Güralp O Ceyhan
- Department of Surgery, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,Department of General Surgery, HPB-Unit, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Horst Kessler
- Institute for Advanced Study, Department of Chemistry and Center for Integrated Protein Science (CIPSM), Technische Universität München, Garching, Germany
| | - Eva Rath
- Chair of Nutrition and Immunology, Technische Universität München, Munich, Germany
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7
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Xu J, Zeug A, Riederer B, Yeruva S, Griesbeck O, Daniel H, Tuo B, Ponimaskin E, Dong H, Seidler U. Calcium-sensing receptor regulates intestinal dipeptide absorption via Ca 2+ signaling and IK Ca activation. Physiol Rep 2020; 8:e14337. [PMID: 31960592 PMCID: PMC6971415 DOI: 10.14814/phy2.14337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although absorption of di- and tripeptides into intestinal epithelial cells occurs via the peptide transporter 1 (PEPT1, also called solute carrier family 15 member 1 (SLC15A1)), the detailed regulatory mechanisms are not fully understood. We examined: (a) whether dipeptide absorption in villous enterocytes is associated with a rise in cytosolic Ca2+ ([Ca2+ ]cyt ), (b) whether the calcium sensing receptor (CaSR) is involved in dipeptide-elicited [Ca2+ ]cyt signaling, and (c) what potential consequences of [Ca2+ ]cyt signaling may enhance enterocyte dipeptide absorption. Dipeptide Gly-Sar and CaSR agonist spermine markedly raised [Ca2+ ]cyt in villous enterocytes, which was abolished by NPS-2143, a selective CaSR antagonist and U73122, an phospholipase C (PLC) inhibitor. Apical application of Gly-Sar induced a jejunal short-circuit current (Isc), which was reduced by NPS-2143. CaSR expression was identified in the lamina propria and on the basal enterocyte membrane of mouse jejunal mucosa in both WT and Slc15a1-/- animals, but Gly-Sar-induced [Ca2+ ]cyt signaling was significantly decreased in Slc15a1-/- villi. Clotrimazole and TRM-34, two selective blockers of the intermediate conductance Ca2+ -activated K+ channel (IKCa ), but not iberiotoxin, a selective blocker of the large-conductance K+ channel (BKCa ) and apamin, a selective blocker of the small-conductance K+ channel (SKCa ), significantly inhibited Gly-Sar-induced Isc in native tissues. We reveal a novel CaSR-PLC-Ca2+ -IKCa pathway in the regulation of small intestinal dipeptide absorption, which may be exploited as a target for future drug development in human nutritional disorders.
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Affiliation(s)
- Jingyu Xu
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Andre Zeug
- Cellular NeurophysiologyHannover Medical SchoolHannoverGermany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Sunil Yeruva
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | | | - Hannelore Daniel
- Nutritional PhysiologyTechnical University of MunichFreisingGermany
| | - Biguang Tuo
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | | | - Hui Dong
- Department of MedicineUniversity of California, San DiegoLa JollaCAUSA
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
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8
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McCauley HA. Enteroendocrine Regulation of Nutrient Absorption. J Nutr 2020; 150:10-21. [PMID: 31504661 DOI: 10.1093/jn/nxz191] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 12/14/2022] Open
Abstract
Enteroendocrine cells (EECs) in the intestine regulate many aspects of whole-body physiology and metabolism. EECs sense luminal and circulating nutrients and respond by secreting hormones that act on multiple organs and organ systems, such as the brain, gallbladder, and pancreas, to control satiety, digestion, and glucose homeostasis. In addition, EECs act locally, on enteric neurons, endothelial cells, and the gastrointestinal epithelium, to facilitate digestion and absorption of nutrients. Many recent reports raise the possibility that EECs and the enteric nervous system may coordinate to regulate gastrointestinal functions. Loss of all EECs results in chronic malabsorptive diarrhea, placing EECs in a central role regulating nutrient absorption in the gut. Because there is increasing evidence that EECs can directly modulate the efficiency of nutrient absorption, it is possible that EECs are master regulators of a feed-forward loop connecting appetite, digestion, metabolism, and abnormally augmented nutrient absorption that perpetuates metabolic disease. This review focuses on the roles that specific EEC hormones play on glucose, peptide, and lipid absorption within the intestine.
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Affiliation(s)
- Heather A McCauley
- Division of Developmental Biology and the Center for Stem Cell and Organoid Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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9
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Ishizuka N, Nakayama M, Watanabe M, Tajima H, Yamauchi Y, Ikari A, Hayashi H. Luminal Na + homeostasis has an important role in intestinal peptide absorption in vivo. Am J Physiol Gastrointest Liver Physiol 2018; 315:G799-G809. [PMID: 30138575 DOI: 10.1152/ajpgi.00099.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal cell line studies indicated luminal Na+ homeostasis is essential for proton-coupled peptide absorption, because the driving force of PepT1 activity is supported by the apical Na+/H+ exchanger NHE3. However, there is no direct evidence demonstrating the importance of in vivo luminal Na+ for peptide absorption in animal experiments. To investigate the relationship between luminal Na+ homeostasis and peptide absorption, we took advantage of claudin 15-deficient (cldn15-/-) mice, whereby Na+ homeostasis is disrupted. We quantitatively assessed the intestinal segment responsible for peptide absorption using radiolabeled nonhydrolyzable dipeptide (glycylsarcosine, Gly-Sar) and nonabsorbable fluid phase marker polyethylene glycol (PEG) 4000 in vivo. In wild-type (WT) mice, the concentration ratio of Gly-Sar to PEG 4000 decreased in the upper jejunum, suggesting the upper jejunum is responsible for peptide absorption. Gly-Sar absorption was decreased in the jejunum of cldn15-/- mice. To elucidate the mechanism underlining these impairments, a Gly-Sar-induced short-circuit ( Isc) current was measured. In WT mice, increments of Gly-Sar-induced Isc were inhibited by the luminal application of a NHE3-specific inhibitor S3226 in a dose-dependent fashion. In contrast to in vivo experiments, robust Gly-Sar-induced Isc increments were observed in the jejunal mucosa of cldn15-/- mice. Gly-Sar-induced Isc was inhibited by S3226 or a reduction of luminal Na+ concentration, which mimics low luminal Na+ concentrations in vivo . Our study demonstrates that luminal Na+ homeostasis is important for peptide absorption in native epithelia and that there is a cooperative functional relationship between PepT1 and NHE3. NEW & NOTEWORTHY Our study is the first to demonstrate that luminal Na+ homeostasis is important for proton-coupled peptide absorption in in vivo animal experiments.
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Affiliation(s)
- Noriko Ishizuka
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Michiko Nakayama
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Miki Watanabe
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Haruna Tajima
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Yuri Yamauchi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Akira Ikari
- Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University , Gifu , Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
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10
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Spanier B, Rohm F. Proton Coupled Oligopeptide Transporter 1 (PepT1) Function, Regulation, and Influence on the Intestinal Homeostasis. Compr Physiol 2018; 8:843-869. [DOI: 10.1002/cphy.c170038] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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11
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Dengler F, Rackwitz R, Pfannkuche H, Gäbel G. Glucose transport across lagomorph jejunum epithelium is modulated by AMP-activated protein kinase under hypoxia. J Appl Physiol (1985) 2017; 123:1487-1500. [PMID: 28860168 DOI: 10.1152/japplphysiol.00436.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The gastrointestinal epithelium possesses adaptation mechanisms to cope with huge variations in blood flow and subsequently oxygenation. Since sufficient energy supply is crucial under hypoxic conditions, glucose uptake especially must be regulated by these adaptation mechanisms. Therefore, we investigated glucose transport under hypoxic conditions. Jejunal epithelia of rabbits were incubated in Ussing chambers under short-circuit current conditions. Hypoxia was simulated by gassing with 1% O2 instead of 100% O2. The activity of sodium-coupled glucose transporter-1 (SGLT-1) was assessed by measuring the increase of short circuit current ( Isc) after the addition of 2 mM glucose to the mucosal buffer solution. We observed decreased activity of SGLT-1 after hypoxia compared with control conditions. To investigate underlying mechanisms, epithelia were exposed to agonists and antagonists of AMP-activated protein kinase (AMPK) before assessment of SGLT-1-mediated transport and the pAMPK/AMPK protein ratio. Preincubation with the antagonist restored SGLT-1 activity under hypoxic conditions to the level of control conditions, indicating an involvement of AMPK in the downregulation of SGLT-1 activity under hypoxia, which was confirmed in Western blot analysis of pAMPK/AMPK. Transepithelial flux studies using radioactively labeled glucose, ortho-methyl-glucose, fructose, and mannitol revealed no changes after hypoxic incubation. Therefore, we could exclude a decreased transepithelial glucose transport rate and increased paracellular conductance under hypoxia. In conclusion, our study hints at a decreased activity of SGLT-1 under hypoxic conditions in an AMPK-dependent manner. However, transepithelial transport of glucose is maintained. Therefore, we suggest other transport mechanisms, especially glucose transporter 1 and/or 2 to substitute SGLT-1 under hypoxia. NEW & NOTEWORTHY To our knowledge, this is the first approach to simulate hypoxia and study its effects in the jejunal epithelium using the Ussing chamber technique. We were able show that AMPK plays a role in the downregulation of SGLT-1 and that there seems to be an upregulation of other glucose transport mechanisms in the apical membrane of lagomorph jejunum epithelium under hypoxia, securing the epithelial energy supply and thus integrity.
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Affiliation(s)
| | - Reiko Rackwitz
- Institute of Veterinary Physiology, University of Leipzig , Germany
| | - Helga Pfannkuche
- Institute of Veterinary Physiology, University of Leipzig , Germany
| | - Gotthold Gäbel
- Institute of Veterinary Physiology, University of Leipzig , Germany
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12
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Gong Y, Zhang J, Wu X, Wang T, Zhao J, Yao Z, Zhang Q, Liu X, Jian X. Specific expression of proton-coupled oligopeptide transporter 1 in primary hepatocarcinoma-a novel strategy for tumor-targeted therapy. Oncol Lett 2017; 14:4158-4166. [PMID: 28943923 PMCID: PMC5592876 DOI: 10.3892/ol.2017.6724] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/16/2017] [Indexed: 12/13/2022] Open
Abstract
Proton-coupled oligopeptide transporter 1 (PEPT1) is a membrane protein which expressed predominantly in intestine and recognized as the target of dietary nutrients (di/tripeptide) or peptidomimetic drug for delivery. The information on the existence of PEPT1 in carcinomas were limited. Our study aimed to investigate the expression profile and transport activity of PEPT1 both in human hepatocarcinoma tissues and cell lines. Western blotting and an immunofluorescence assay revealed the high level of PEPT1 protein expression in hepatocarcinoma Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cell lines. Quantitative real time PCR showed the mRNA expression of PEPT1 in Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cells. High level PEPT1 expression in hepatocarcinoma patient samples were observed by Immunohistology and showed a significant correlation between protein level and pathological grade. Functional activities were also studied using D-Ala-Lys-AMCA (a substrate of peptide transporter) in above five hepatocarcinoma cell lines. The uptake tests performed by fluorescent microscopy suggested that PEPT1 can transport both D-Ala-Lys-AMCA into the hepatocarcinoma cells and the uptake can be competitively inhibited by three PEPT1 substrates (Gly-sar, Gly-gln and Glyglygly). In conclusion, our findings provided the novel information on the expression and function of PEPT1 in human hepatocarcinoma and expanded the potential values for tumor specific drug delivery.
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Affiliation(s)
- Yanxia Gong
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.,Department of Gastroenterology, Tianjin Nankai Hospital, Tianjin 300100, P.R. China
| | - Jie Zhang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xiang Wu
- Central Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Tao Wang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Jia Zhao
- Clinical Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Zhi Yao
- Department of Immunology, School of Basic Medical Science, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Qingyu Zhang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xi Liu
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xu Jian
- Central Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
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13
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Thammayon N, Wongdee K, Lertsuwan K, Suntornsaratoon P, Thongbunchoo J, Krishnamra N, Charoenphandhu N. Na +/H + exchanger 3 inhibitor diminishes the amino-acid-enhanced transepithelial calcium transport across the rat duodenum. Amino Acids 2016; 49:725-734. [PMID: 27981415 DOI: 10.1007/s00726-016-2374-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/29/2016] [Indexed: 12/22/2022]
Abstract
Na+/H+ exchanger (NHE)-3 is important for intestinal absorption of nutrients and minerals, including calcium. The previous investigations have shown that the intestinal calcium absorption is also dependent on luminal nutrients, but whether aliphatic amino acids and glucose, which are abundant in the luminal fluid during a meal, similarly enhance calcium transport remains elusive. Herein, we used the in vitro Ussing chamber technique to determine epithelial electrical parameters, i.e., potential difference (PD), short-circuit current (Isc), and transepithelial resistance, as well as 45Ca flux in the rat duodenum directly exposed on the mucosal side to glucose or various amino acids. We found that mucosal glucose exposure led to the enhanced calcium transport, PD, and Isc, all of which were insensitive to NHE3 inhibitor (100 nM tenapanor). In the absence of mucosal glucose, several amino acids (12 mM in the mucosal side), i.e., alanine, isoleucine, leucine, proline, and hydroxyproline, markedly increased the duodenal calcium transport. An inhibitor for NHE3 exposure on the mucosal side completely abolished proline- and leucine-enhanced calcium transport, but not transepithelial transport of both amino acids themselves. In conclusion, glucose and certain amino acids in the mucosal side were potent stimulators of the duodenal calcium absorption, but only amino-acid-enhanced calcium transport was NHE3-dependent.
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Affiliation(s)
- Nithipak Thammayon
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Kannikar Wongdee
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Faculty of Allied Health Sciences, Burapha University, Chonburi, 20131, Thailand
| | - Kornkamon Lertsuwan
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand
| | - Panan Suntornsaratoon
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Jirawan Thongbunchoo
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Nateetip Krishnamra
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Narattaphol Charoenphandhu
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand. .,Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170, Thailand.
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14
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Di- and tripeptide transport in vertebrates: the contribution of teleost fish models. J Comp Physiol B 2016; 187:395-462. [PMID: 27803975 DOI: 10.1007/s00360-016-1044-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 02/06/2023]
Abstract
Solute Carrier 15 (SLC15) family, alias H+-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their role in the cellular uptake of di- and tripeptides (di/tripeptides) and peptide-like molecules. Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from dietary protein digestion, while SLC15A2 (PEPT2) mainly allows renal tubular reabsorption of di/tripeptides from ultrafiltration, SLC15A3 (PHT2) and SLC15A4 (PHT1) possibly interact with di/tripeptides and histidine in certain immune cells, and SLC15A5 has unknown function. Our understanding of this family in vertebrates has steadily increased, also due to the surge of genomic-to-functional information from 'non-conventional' animal models, livestock, poultry, and aquaculture fish species. Here, we review the literature on the SLC15 transporters in teleost fish with emphasis on SLC15A1 (PEPT1), one of the solute carriers better studied amongst teleost fish because of its relevance in animal nutrition. We report on the operativity of the transporter, the molecular diversity, and multiplicity of structural-functional solutions of the teleost fish orthologs with respect to higher vertebrates, its relevance at the intersection of the alimentary and osmoregulative functions of the gut, its response under various physiological states and dietary solicitations, and its possible involvement in examples of total body plasticity, such as growth and compensatory growth. By a comparative approach, we also review the few studies in teleost fish on SLC15A2 (PEPT2), SLC15A4 (PHT1), and SLC15A3 (PHT2). By representing the contribution of teleost fish to the knowledge of the physiology of di/tripeptide transport and transporters, we aim to fill the gap between higher and lower vertebrates.
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15
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Sampaio IC, Medeiros PHQS, Rodrigues FAP, Cavalcante PA, Ribeiro SA, Oliveira JS, Prata MMG, Costa DVS, Fonseca SGC, Guedes MM, Soares AM, Brito GAC, Havt A, Moore SR, Lima AAM. Impact of acute undernutrition on growth, ileal morphology and nutrient transport in a murine model. ACTA ACUST UNITED AC 2016; 49:e5340. [PMID: 27737316 PMCID: PMC5064774 DOI: 10.1590/1414-431x20165340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/24/2016] [Indexed: 12/16/2022]
Abstract
Undernutrition represents a major public health challenge for middle- and low-income
countries. This study aimed to evaluate whether a multideficient Northeast Brazil
regional basic diet (RBD) induces acute morphological and functional changes in the
ileum of mice. Swiss mice (∼25 g) were allocated into two groups: i) control mice
were fed a standard diet and II) undernourished mice were fed the RBD. After 7 days,
mice were killed and the ileum collected for evaluation of electrophysiological
parameters (Ussing chambers), transcription (RT-qPCR) and protein expression (western
blotting) of intestinal transporters and tight junctions. Body weight gain was
significantly decreased in the undernourished group, which also showed decreased
crypt depth but no alterations in villus height. Electrophysiology measurements
showed a reduced basal short circuit current (Isc) in the undernourished group, with no differences in transepithelial
resistance. Specific substrate-evoked Isc related to affinity and efficacy (glutamine and alanyl-glutamine) were
not different between groups, except for the maximum Isc (efficacy) induced by glucose. Transcription of Sglt1
and Pept1 was significantly higher in the undernourished group,
while SN-2 transcription was decreased. No changes were found in
transcription of CAT-1 and CFTR, while claudin-2 and occludin transcriptions were
significantly increased in the undernourished group. Despite mRNA changes, SGLT-1,
PEPT-1, claudin-2 and occludin protein expression showed no difference between
groups. These results demonstrate early effects of the RBD on mice, which include
reduced body weight and crypt depth in the absence of significant alterations to
villus morphology, intestinal transporters and tight junction expression.
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Affiliation(s)
- I C Sampaio
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - P H Q S Medeiros
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - F A P Rodrigues
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - P A Cavalcante
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - S A Ribeiro
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - J S Oliveira
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - M M G Prata
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - D V S Costa
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - S G C Fonseca
- Departamento de Farmácia, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - M M Guedes
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - A M Soares
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - G A C Brito
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - A Havt
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
| | - S R Moore
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - A A M Lima
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Instituto de Biomedicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
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16
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Zhang Y, Viennois E, Zhang M, Xiao B, Han MK, Walter L, Garg P, Merlin D. PepT1 Expression Helps Maintain Intestinal Homeostasis by Mediating the Differential Expression of miRNAs along the Crypt-Villus Axis. Sci Rep 2016; 6:27119. [PMID: 27250880 PMCID: PMC4890533 DOI: 10.1038/srep27119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/12/2016] [Indexed: 01/25/2023] Open
Abstract
In the jejunum, PepT1 is particularly enriched in the well-differentiated absorptive epithelial cells in the villi. Studies of expression and function of PepT1 along the crypt-villus axis demonstrated that this protein is crucial to the process of di/tripeptide absorption. We recently exhibited that PepT1 plays an important role in multiple biological functions, including the ability to regulate the expression/secretion of specific microRNAs (miRNAs) and the expression levels of multiple proteins. In this study, we observed that PepT1 knockout (KO) mice exhibited reduced body weight and shorten intestinal microvilli. We then examined the expression levels of various miRNAs and their target proteins along the crypt-villi axis in the jejunum of PepT1 KO mice. We found that PepT1 KO altered the distribution of miRNAs along the crypt-villus axis and changed the miRNA profiles of both villi and crypts. Using miRNA-target prediction and 2D-DIGE/mass spectrometry on villi and crypts samples, we found that ablation of PepT1 further directly or indirectly altered expression levels of certain protein targets. Collectively, our results suggest that PepT1 contributes to maintain balance of homeostasis and proper functions in the small intestine, and dysregulated miRNAs and proteins along the crypt-villus axis are highly related to this process.
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Affiliation(s)
- Yuchen Zhang
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Emilie Viennois
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Mingzhen Zhang
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Bo Xiao
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA.,Institute for Clean Energy and Advanced Materials, Faculty for Materials and Energy, Southwest University, Chongqing, 400715, P. R. China
| | - Moon Kwon Han
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Lewins Walter
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Pallavi Garg
- Department of Biology, Georgia State University, Atlanta, Georgia, 30302, USA
| | - Didier Merlin
- Institute for Biomedical Sciences, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, 30302, USA.,Atlanta Veterans Affairs Medical Center, Decatur, Georgia, 30033, USA
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17
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Yu Q, Liu X, Liu Y, Riederer B, Li T, Tian DA, Tuo B, Shull G, Seidler U. Defective small intestinal anion secretion, dipeptide absorption, and intestinal failure in suckling NBCe1-deficient mice. Pflugers Arch 2016; 468:1419-32. [PMID: 27228994 PMCID: PMC4951514 DOI: 10.1007/s00424-016-1836-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/05/2016] [Accepted: 05/09/2016] [Indexed: 11/27/2022]
Abstract
The electrogenic Na+HCO3− cotransporter NBCe1 (Slc4a4) is strongly expressed in the basolateral enterocyte membrane in a villous/surface predominant fashion. In order to better understand its physiological function in the intestine, isolated mucosae in miniaturized Ussing chambers and microdissected intestinal villi or crypts loaded with the fluorescent pH-indicator BCECF were studied from the duodenum, jejunum, and colon of 14- to 17-days-old slc4a4-deficient (KO) and WT mice. NBCe1 was active in the basal state in all intestinal segments under study, most likely to compensate for acid loads imposed upon the enterocytes. Upregulation of other basolateral base uptake mechanism occurs, but in a segment-specific fashion. Loss of NBCe1 resulted in severely impaired Cl− and fluid secretory response, but not HCO3− secretory response to agonist stimulation. In addition, NBCe1 was found to be active during transport processes that load the surface enterocytes with acid, such as Slc26a3 (DRA)-mediated luminal Cl−/HCO3− exchange or PEPT1-mediated H+/dipeptide uptake. Possibly because of the high energy demand for hyperventilation in conjunction with the fluid secretory and nutrient absorptive defects and the relative scarcity of compensatory mechanisms, NBCe1-deficient mice developed progressive jejunal failure, worsening of metabolic acidosis, and death in the third week of life. Our data suggest that the electrogenic influx of base via NBCe1 maintains enterocyte anion homeostasis and pHi control. Its loss impairs small intestinal Cl− and fluid secretion as well as the neutralization of acid loads imposed on the enterocytes during nutrient and electrolyte absorption.
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Affiliation(s)
- Qin Yu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastroenterology, Tongji Hospital, Huazhong University of Science & Technology, Wuhan, People's Republic of China
| | - Xuemei Liu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastroenterology, Zunyi Medical College, Zunyi, China
| | - Yongjian Liu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Taolang Li
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastrointestinal Surgery, Zunyi Medical College, Zunyi, China
| | - De-An Tian
- Department of Gastroenterology, Tongji Hospital, Huazhong University of Science & Technology, Wuhan, People's Republic of China
| | - Biguang Tuo
- Department of Gastroenterology, Zunyi Medical College, Zunyi, China
| | - Gary Shull
- Department of of Molecular Genetics, University of Cincinnati, Cincinnati, OH, USA
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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18
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Ito K, Yamaguchi M, Noma T, Yamaji T, Itoh H, Oda M. Whey protein hydrolysates enhance water absorption in the perfused small intestine of anesthetized rats. Biosci Biotechnol Biochem 2016; 80:1587-93. [PMID: 27055721 DOI: 10.1080/09168451.2016.1166931] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We evaluated the effect of whey protein hydrolysates (WPH) on the water absorption rate in the small intestine using a rat small intestine perfusion model. The rate was significantly higher with 5 g/L WPH than with 5 g/L soy protein hydrolysates or physiological saline (p < 0.05). WPH dose-dependently increased the water absorption rate in the range of 1.25-10.0 g/L. WPH showed a significantly higher rate than an amino acid mixture whose composition was equal to that of WPH (p < 0.05). The addition of 4-aminomethylbenzoic acid, an inhibitor of PepT1, significantly suppressed WPH's enhancement of water absorption (p < 0.05). The rate of water absorption was significantly correlated with that of peptides/amino acids absorption in WPH (r = 0.82, p < 0.01). These data suggest that WPH have a high water absorption-promoting effect, to which PepT1 contributes.
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Affiliation(s)
- Kentaro Ito
- a Food Science Research Laboratories, R&D Division , Meiji Co., Ltd. , Odawara , Japan
| | - Makoto Yamaguchi
- a Food Science Research Laboratories, R&D Division , Meiji Co., Ltd. , Odawara , Japan
| | - Teruyuki Noma
- a Food Science Research Laboratories, R&D Division , Meiji Co., Ltd. , Odawara , Japan
| | - Taketo Yamaji
- a Food Science Research Laboratories, R&D Division , Meiji Co., Ltd. , Odawara , Japan
| | - Hiroyuki Itoh
- a Food Science Research Laboratories, R&D Division , Meiji Co., Ltd. , Odawara , Japan
| | - Munehiro Oda
- b College of Bioresource Sciences, Nihon University , Fujisawa , Japan
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19
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Ito K, Saito Y, Yamaguchi M, Ashida K, Yamaji T, Itoh H, Takahashi T, Oda M. Addition of Whey Peptides to a Carbohydrate-electrolyte Drink Enhances its Effect on the Early Treatment of Dehydration in Rats. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2016. [DOI: 10.3136/fstr.22.623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Kentaro Ito
- Food Science Research Labs, R&D Division, Meiji Co., Ltd
| | - Yuri Saito
- Food Science Research Labs, R&D Division, Meiji Co., Ltd
| | | | - Kinya Ashida
- Food Science Research Labs, R&D Division, Meiji Co., Ltd
| | - Taketo Yamaji
- Food Science Research Labs, R&D Division, Meiji Co., Ltd
| | - Hiroyuki Itoh
- Food Science Research Labs, R&D Division, Meiji Co., Ltd
| | - Toru Takahashi
- Graduate School of Human Environment Science, Fukuoka Women's University
| | - Munehiro Oda
- College of Bioresource Sciences, Nihon University
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20
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Zietek T, Rath E, Haller D, Daniel H. Intestinal organoids for assessing nutrient transport, sensing and incretin secretion. Sci Rep 2015; 5:16831. [PMID: 26582215 PMCID: PMC4652176 DOI: 10.1038/srep16831] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 10/21/2015] [Indexed: 12/31/2022] Open
Abstract
Intestinal nutrient transport and sensing are of emerging interest in research on obesity and diabetes and as drug targets. Appropriate in vitro models are lacking that allow both, studies on transport processes as well as sensing and subsequent incretin hormone secretion including intracellular signaling. We here demonstrate that murine small-intestinal organoids are the first in vitro model system enabling concurrent investigations of nutrient and drug transport, sensing and incretin hormone secretion as well as fluorescent live-cell imaging of intracellular signaling processes. By generating organoid cultures from wild type mice and animals lacking different nutrient transporters, we show that organoids preserve the main phenotypic features and functional characteristics of the intestine. This turns them into the best in vitro model currently available and opens new avenues for basic as well as medical research.
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Affiliation(s)
- Tamara Zietek
- Department of Nutritional Physiology, Technische Universität München, 85350 Freising, Germany.,ZIEL-Institute for Food &Health, 85350 Freising, Germany
| | - Eva Rath
- ZIEL-Institute for Food &Health, 85350 Freising, Germany.,Chair of Nutrition and Immunology, Technische Universität München, 85350 Freising, Germany
| | - Dirk Haller
- ZIEL-Institute for Food &Health, 85350 Freising, Germany.,Chair of Nutrition and Immunology, Technische Universität München, 85350 Freising, Germany
| | - Hannelore Daniel
- Department of Nutritional Physiology, Technische Universität München, 85350 Freising, Germany.,ZIEL-Institute for Food &Health, 85350 Freising, Germany
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21
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Xia W, Yu Q, Riederer B, Singh AK, Engelhardt R, Yeruva S, Song P, Tian DA, Soleiman M, Seidler U. The distinct roles of anion transporters Slc26a3 (DRA) and Slc26a6 (PAT-1) in fluid and electrolyte absorption in the murine small intestine. Pflugers Arch 2015; 466:1541-56. [PMID: 24233434 PMCID: PMC4092241 DOI: 10.1007/s00424-013-1381-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 01/06/2023]
Abstract
The mixing of gastric and pancreatic juice subjects the jejunum to unique ionic conditions with high luminal CO2 tension and HCO3− concentration. We investigated the role of the small intestinal apical anion exchangers PAT-1 (Slc26a6) and DRA (Slc26a3) in basal and CO2/HCO3−-stimulated jejunal fluid absorption. Single pass perfusion of jejunal segments was performed in anaesthetised wild type (WT) as well as in mice deficient in DRA, PAT-1, Na+/H+ exchanger 3 (NHE3) or NHE2, and in carbonic anhydrase II (CAII). Unbuffered saline (pH 7.4) perfusion of WT jejunum resulted in fluid absorption and acidification of the effluent. DRA-deficient jejunum absorbed less fluid than WT, and acidified the effluent more strongly, consistent with its action as a Cl−/HCO3− exchanger. PAT-1-deficient jejunum also absorbed less fluid but resulted in less effluent acidification. Switching the luminal solution to a 5 % CO2/HCO3− buffered solution (pH 7.4), resulted in a decrease in jejunal enterocyte pHi in all genotypes, an increase in luminal surface pH and a strong increase in fluid absorption in a PAT-1- and NHE3- but not DRA-, CAII, or NHE2-dependent fashion. Even in the absence of luminal Cl−, luminal CO2/HCO3− augmented fluid absorption in WT, CAII, NHE2- or DRA-deficient, but not in PAT-1- or NHE3-deficient mice, indicating the likelihood that PAT-1 serves to import HCO3− and NHE3 serves to import Na+ under these circumstances. The results suggest that PAT-1 plays an important role in jejunal Na+HCO3– reabsorption, while DRA absorbs Cl− and exports HCO3− in a partly CAII-dependent fashion. Both PAT-1 and DRA significantly contribute to intestinal fluid absorption and enterocyte acid/base balance but are activated by different ion gradients.
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22
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Sultan A, Luo M, Yu Q, Riederer B, Xia W, Chen M, Lissner S, Gessner JE, Donowitz M, Yun CC, deJonge H, Lamprecht G, Seidler U. Differential association of the Na+/H+ Exchanger Regulatory Factor (NHERF) family of adaptor proteins with the raft- and the non-raft brush border membrane fractions of NHE3. Cell Physiol Biochem 2014; 32:1386-402. [PMID: 24297041 DOI: 10.1159/000356577] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIMS Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. METHODS Detergent resistant membranes ("lipid rafts") were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3(-) mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. RESULTS NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. CONCLUSIONS The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs.
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Kottra G, Spanier B, Verri T, Daniel H. Peptide transporter isoforms are discriminated by the fluorophore-conjugated dipeptides β-Ala- and d-Ala-Lys-N-7-amino-4-methylcoumarin-3-acetic acid. Physiol Rep 2013; 1:e00165. [PMID: 24744852 PMCID: PMC3970736 DOI: 10.1002/phy2.165] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/16/2013] [Accepted: 10/26/2013] [Indexed: 02/06/2023] Open
Abstract
Peptide transporters of the SLC15 family are classified by structure and function into PEPT1 (low‐affinity/high‐capacity) and PEPT2 (high‐affinity/low‐capacity) isoforms. Despite the differences in kinetics, both transporter isoforms are reckoned to transport essentially all possible di‐ and tripeptides. We here report that the fluorophore‐conjugated dipeptide derivatives β‐Ala‐Lys‐N‐7‐amino‐4‐methylcoumarin‐3‐acetic acid (β‐AK‐AMCA) and d‐Ala‐Lys‐N‐7‐amino‐4‐methylcoumarin‐3‐acetic acid (d‐AK‐AMCA) are transported by distinct PEPT isoforms in a species‐specific manner. Transport of the fluorophore peptides was studied (1) in vitro after heterologous expression in Xenopus oocytes of PEPT1 and PEPT2 isoforms from different vertebrate species and of PEPT1 and PEPT2 transporters from Caenorhabditis elegans by using electrophysiological and fluorescence methods and (2) in vivo in C. elegans by using fluorescence methods. Our results indicate that both substrates are transported by the vertebrate “renal‐type” and the C. elegans “intestinal‐type” peptide transporter only. A systematic analysis among species finds four predicted amino acid residues along the sequence that may account for the substrate uptake differences observed between the vertebrate PEPT1/nematode PEPT2 and the vertebrate PEPT2/nematode PEPT1 subtype. This selectivity on basis of isoforms and species may be helpful in better defining the structure–function determinants of the proteins of the SLC15 family. Peptide transporters of the SLC15 family can be classified by structure and function into the PEPT1 (low‐affinity/high‐capacity) and PEPT2 (high‐affinity/low‐capacity) phenotype. We found that the fluorophore‐conjugated dipeptide derivatives β‐Ala‐Lys‐N‐7‐amino‐4‐methylcoumarin‐3‐acetic acid (β‐AK‐AMCA) and d‐Ala‐Lys‐N‐7‐amino‐4‐methylcoumarin‐3‐acetic acid (d‐AK‐AMCA) are transported only by distinct PEPT isoforms in a species‐specific manner. This selectivity on basis of isoforms and species should be helpful in further defining the substrate‐binding domain of peptide transporters.
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Affiliation(s)
- Gabor Kottra
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Gregor-Mendel-Str. 2, Freising, D-85350, Germany
| | - Britta Spanier
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Gregor-Mendel-Str. 2, Freising, D-85350, Germany
| | - Tiziano Verri
- Laboratory of General Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, via Provinciale Lecce-Monteroni, Lecce, I-73100, Italy
| | - Hannelore Daniel
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Gregor-Mendel-Str. 2, Freising, D-85350, Germany
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Coon SD, Schwartz JH, Rajendran VM, Jepeal L, Singh SK. Glucose-dependent insulinotropic polypeptide regulates dipeptide absorption in mouse jejunum. Am J Physiol Gastrointest Liver Physiol 2013; 305:G678-84. [PMID: 24072682 PMCID: PMC3840233 DOI: 10.1152/ajpgi.00098.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) secreted from jejunal mucosal K cells augments insulin secretion and plays a critical role in the pathogenesis of obesity and Type 2 diabetes mellitus. In recent studies, we have shown GIP directly activates Na-glucose cotransporter-1 (SGLT1) and enhances glucose absorption in mouse jejunum. It is not known whether GIP would also regulate other intestinal nutrient absorptive processes. The present study investigated the effect of GIP on proton-peptide cotransporter-1 (PepT1) that mediates di- and tripeptide absorption as well as peptidomimetic drugs. Immunohistochemistry studies localized both GIP receptor (GIPR) and PepT1 proteins on the basolateral and apical membranes of normal mouse jejunum, respectively. Anti-GIPR antibody detected 50-, 55-, 65-, and 70-kDa proteins, whereas anti-PepT1 detected a 70-kDa proteins in mucosal homogenates of mouse jejunum. RT-PCR analyses established the expression of GIPR- and PepT1-specific mRNA in mucosal cells of mouse jejunum. Absorption of Gly-Sar (a nondigestible dipeptide) measured under voltage-clamp conditions revealed that the imposed mucosal H(+) gradient-enhanced Gly-Sar absorption as an evidence for the presence of PepT1-mediated H(+):Gly-Sar cotransport on the apical membranes of mouse jejunum. H(+):Gly-Sar absorption was completely inhibited by cephalexin (a competitive inhibitor of PepT1) and was activated by GIP. The GIP-activated Gly-Sar absorption was completely inhibited by RP-cAMP (a cAMP antagonist). In contrast to GIP, the ileal L cell secreting glucagon-like peptide-1 (GLP-1) did not affect the H(+):Gly-Sar absorption in mouse jejunum. We conclude from these observations that GIP, but not GLP-1, directly activates PepT1 activity by a cAMP-dependent signaling pathway in jejunum.
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Affiliation(s)
- Steven D. Coon
- 1Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; ,2Veterans Affairs Boston Healthcare System, Boston, Massachusetts; ,3Boston University Clinical and Translational Science Institute, Boston, Massachusetts; and
| | - John H. Schwartz
- 1Department of Medicine, Boston University School of Medicine, Boston, Massachusetts;
| | - Vazhaikkurichi M. Rajendran
- 4Department of Biochemistry and Molecular Biology, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Lisa Jepeal
- 1Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; ,2Veterans Affairs Boston Healthcare System, Boston, Massachusetts;
| | - Satish K. Singh
- 1Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; ,2Veterans Affairs Boston Healthcare System, Boston, Massachusetts;
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Northern contaminant mixtures induced morphological and functional changes in human coronary artery endothelial cells under culture conditions typifying high fat/sugar diet and ethanol exposure. Toxicology 2013; 313:103-12. [DOI: 10.1016/j.tox.2013.01.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 11/22/2012] [Accepted: 01/27/2013] [Indexed: 01/09/2023]
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Spanier B. Transcriptional and functional regulation of the intestinal peptide transporter PEPT1. J Physiol 2013; 592:871-9. [PMID: 23959672 DOI: 10.1113/jphysiol.2013.258889] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Dietary proteins are cleaved within the intestinal lumen to oligopeptides which are further processed to small peptides (di- and tripeptides) and free amino acids. Although the transport of amino acids is mediated by several specific amino acid transporters, the proton-coupled uptake of the more than 8000 different di- and tripeptides is performed by the high-capacity/low-affinity peptide transporter isoform PEPT1 (SLC15A1). Its wide substrate tolerance also allows the transport of a repertoire of structurally closely related compounds and drugs, which explains their high oral bioavailability and brings PEPT1 into focus for medical and pharmaceutical approaches. Although the first evidence for the interplay of nutrient supply and PEPT1 expression and function was described over 20 years ago, many aspects of the molecular processes controlling its transcription and translation and modifying its transporter properties are still awaiting discovery. The present review summarizes the recent knowledge on the factors modulating PEPT1 expression and function in Caenorhabditis elegans, Danio rerio, Mus musculus and Homo sapiens, with focus on dietary ingredients, transcription factors and functional modulators, such as the sodium-proton exchanger NHE3 and selected scaffold proteins.
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Affiliation(s)
- Britta Spanier
- Biochemistry, Technische Universität München, ZIEL Research Center of Nutrition and Food Sciences, Gregor-Mendel-Straße 2, D-85350 Freising, Germany.
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27
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Wuensch T, Schulz S, Ullrich S, Lill N, Stelzl T, Rubio-Aliaga I, Loh G, Chamaillard M, Haller D, Daniel H. The peptide transporter PEPT1 is expressed in distal colon in rodents and humans and contributes to water absorption. Am J Physiol Gastrointest Liver Physiol 2013; 305:G66-73. [PMID: 23660505 DOI: 10.1152/ajpgi.00491.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The peptide transporter PEPT1, expressed in the brush border membrane of enterocytes, mediates the uptake of di- and tripeptides from luminal protein digestion in the small intestine. PEPT1 was proposed not to be expressed in normal colonic mucosa but may become detectable in inflammatory states such as Crohn's disease or ulcerative colitis. We reassessed colonic expression of PEPT1 by performing a systematic analysis of PEPT1 mRNA and protein levels in healthy colonic tissues in mice, rats, and humans. Immunofluorescence analysis of different mouse strains (C57BL/6N, 129/Sv, BALB/c) demonstrated the presence of PEPT1 in the distal part of the colon but not in proximal colon. Rat and human intestines display a similar distribution of PEPT1 as found in mice. However, localization in human sigmoid colon revealed immunoreactivity present at low levels in apical membranes but substantial staining in distinct intracellular compartments. Functional activity of PEPT1 in colonic tissues from mice was assessed in everted sac preparations using [¹⁴C]Gly-Sar and found to be 5.7-fold higher in distal compared with proximal colon. In intestinal tissues from Pept1-/- mice, no [¹⁴C]Gly-Sar transport was detectable but feces samples revealed significantly higher water content than in wild-type mice, suggesting that PEPT1 contributes to colonic water absorption. In conclusion, our studies unequivocally demonstrate the presence of PEPT1 protein in healthy distal colonic epithelium in mice, rats, and humans and proved that the protein is functional and contributes to electrolyte and water handling in mice.
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Affiliation(s)
- Tilo Wuensch
- Technische Universität München, Biochemistry Unit, ZIEL-Research Center for Nutrition and Food Science, CDD-Center for Diet and Disease, Freising-Weihenstephan, Germany
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Kolodziejczak D, Spanier B, Pais R, Kraiczy J, Stelzl T, Gedrich K, Scherling C, Zietek T, Daniel H. Mice lacking the intestinal peptide transporter display reduced energy intake and a subtle maldigestion/malabsorption that protects them from diet-induced obesity. Am J Physiol Gastrointest Liver Physiol 2013; 304:G897-907. [PMID: 23494121 DOI: 10.1152/ajpgi.00160.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal transporter PEPT1 mediates the absorption of di- and tripeptides originating from breakdown of dietary proteins. Whereas mice lacking PEPT1 did not display any obvious changes in phenotype on a high-carbohydrate control diet (HCD), Pept1(-/-) mice fed a high-fat diet (HFD) showed a markedly reduced weight gain and reduced body fat stores. They were additionally protected from hyperglycemia and hyperinsulinemia. Energy balance studies revealed that Pept1(-/-) mice on HFD have a reduced caloric intake, no changes in energy expenditure, but increased energy content in feces. Cecal biomass in Pept1(-/-) mice was as well increased twofold on both diets, suggesting a limited capacity in digesting and/or absorbing the dietary constituents in the small intestine. GC-MS-based metabolite profiling of cecal contents revealed high levels and a broad spectrum of sugars in PEPT1-deficient mice on HCD, whereas animals fed HFD were characterized by high levels of free fatty acids and absence of sugars. In search of the origin of the impaired digestion/absorption, we observed that Pept1(-/-) mice lack the adaptation of the upper small intestinal mucosa to the trophic effects of the diet. Whereas wild-type mice on HFD adapt to diet with increased villus length and surface area, Pept1(-/-) mice failed to show this response. In search for the origin of this, we recorded markedly reduced systemic IL-6 levels in all Pept1(-/-) mice, suggesting that IL-6 could contribute to the lack of adaptation of the mucosal architecture to the diets.
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Affiliation(s)
- Dominika Kolodziejczak
- Biochemistry, Technische Universität München, ZIEL Research Center of Nutrition and Food Sciences, Gregor-Mendel-Straße 2, D-85350 Freising, Germany
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29
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Furutani J, Segawa H, Aranami F, Kuwahara S, Sugano M, Bannai K, Yamato H, Ito M, Miyamoto KI. Dietary inorganic phosphorus regulates the intestinal peptide transporter PepT1. J Ren Nutr 2012; 23:e11-20. [PMID: 22677630 DOI: 10.1053/j.jrn.2012.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/18/2012] [Accepted: 02/21/2012] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Both organic and inorganic phosphorus (Pi) are present in regularly consumed foods, such as meats, eggs, and dairy products. Pi is often included in foods as an additive (as hidden phosphorus). The intestinal peptide transporter PepT1 mediates protein absorption, which is disturbed in renal insufficiency. Our aim was to determine the effects of dietary Pi content on the peptide transport activity and expression of PepT1. METHODS The following animal models were used: (1) 7-week-old male Wistar rats; and (2) rats that underwent 3/4 nephrectomy to induce chronic kidney disease (CKD). The rats were fed a normal-protein (20%) diet containing low (0.02%), normal (0.6%), or high (1.2%) Pi levels. They were also fed diets containing varying amounts of protein and either low or normal Pi levels as follows: (1) low Pi/normal protein, (2) low Pi/high (50%) protein, (3) normal Pi/normal protein, and (4) normal Pi/high protein. RESULTS Intestinal peptide transport activity and PepT1 expression levels were significantly higher in the CKD rats than in sham-operated control ones. Compared with the normal-protein diet, the high-protein diet increased PepT1 expression in the CKD rats. Intestinal dipeptide transport activity and PepT1 protein levels did not increase in the rats fed the low-Pi/high-protein diet. In contrast, intestinal dipeptide transport activity and PepT1 protein expression were markedly increased in the rats fed the normal-Pi/high-protein diet. CONCLUSION Dietary Pi levels regulate intestinal peptide transport activity through PepT1.
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Affiliation(s)
- Junya Furutani
- Department of Molecular Nutrition, Institution of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
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30
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Gallagher MF, Heffron CC, Laios A, O'Toole SA, Ffrench B, Smyth PC, Flavin RJ, Elbaruni SA, Spillane CD, Martin CM, Sheils OM, O'Leary JJ. Suppression of cancer stemness p21-regulating mRNA and microRNA signatures in recurrent ovarian cancer patient samples. J Ovarian Res 2012; 5:2. [PMID: 22260314 PMCID: PMC3285047 DOI: 10.1186/1757-2215-5-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 01/19/2012] [Indexed: 01/05/2023] Open
Abstract
Background Malignant ovarian disease is characterised by high rates of mortality due to high rates of recurrent chemoresistant disease. Anecdotal evidence indicates this may be due to chemoresistant properties of cancer stem cells (CSCs). However, our understanding of the role of CSCs in recurrent ovarian disease remains sparse. In this study we used gene microarrays and meta-analysis of our previously published microRNA (miRNA) data to assess the involvement of cancer stemness signatures in recurrent ovarian disease. Methods Microarray analysis was used to characterise early regulation events in an embryonal carcinoma (EC) model of cancer stemness. This was then compared to our previously published microarray data from a study of primary versus recurrent ovarian disease. In parallel, meta-analysis was used to identify cancer stemness miRNA signatures in tumor patient samples. Results Microarray analysis demonstrated a 90% difference between gene expression events involved in early regulation of differentiation in murine EC (mEC) and embryonic stem (mES) cells. This contrasts the known parallels between mEC and mES cells in the undifferentiated and well-differentiated states. Genelist comparisons identified a cancer stemness signature set of genes in primary versus recurrent data, a subset of which are known p53-p21 regulators. This signature is present in primary and recurrent or in primary alone but essentially never in recurrent tumors specifically. Meta-analysis of miRNA expression showed a much stronger cancer stemness signature within tumor samples. This miRNA signature again related to p53-p21 regulation and was expressed prominently in recurrent tumors. Our data indicate that the regulation of p53-p21 in ovarian cancer involves, at least partially, a cancer stemness component. Conclusion We present a p53-p21 cancer stemness signature model for ovarian cancer. We propose that this may, at least partially, differentially regulate the p53-p21 mechanism in ovarian disease. Targeting CSCs within ovarian cancer represents a potential therapeutic avenue.
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Affiliation(s)
- Michael F Gallagher
- Department of Histopathology, University of Dublin, Trinity College, Trinity Centre for Health Sciences, St James' Hospital, Dublin 8, Ireland.
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Nässl AM, Rubio-Aliaga I, Sailer M, Daniel H. The intestinal peptide transporter PEPT1 is involved in food intake regulation in mice fed a high-protein diet. PLoS One 2011; 6:e26407. [PMID: 22031831 PMCID: PMC3198773 DOI: 10.1371/journal.pone.0026407] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/26/2011] [Indexed: 01/04/2023] Open
Abstract
High-protein diets are effective in achieving weight loss which is mainly explained by increased satiety and thermogenic effects. Recent studies suggest that the effects of protein-rich diets on satiety could be mediated by amino acids like leucine or arginine. Although high-protein diets require increased intestinal amino acid absorption, amino acid and peptide absorption has not yet been considered to contribute to satiety effects. We here demonstrate a novel finding that links intestinal peptide transport processes to food intake, but only when a protein-rich diet is provided. When mice lacking the intestinal peptide transporter PEPT1 were fed diets containing 8 or 21 energy% of protein, no differences in food intake and weight gain were observed. However, upon feeding a high-protein (45 energy%) diet, Pept1(-/-) mice reduced food intake much more pronounced than control animals. Although there was a regain in food consumption after a few days, no weight gain was observed which was associated with a reduced intestinal energy assimilation and increased fecal energy losses. Pept1(-/-) mice on high-protein diet displayed markedly reduced plasma leptin levels during the period of very low food intake, suggesting a failure of leptin signaling to increase energy intake. This together with an almost two-fold elevated plasma arginine level in Pept1(-/-) but not wildtype mice, suggests that a cross-talk of arginine with leptin signaling in brain, as described previously, could cause these striking effects on food intake.
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Affiliation(s)
- Anna-Maria Nässl
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany
| | - Isabel Rubio-Aliaga
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany
| | - Manuela Sailer
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany
| | - Hannelore Daniel
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany
- * E-mail:
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Jappar D, Hu Y, Smith DE. Effect of dose escalation on the in vivo oral absorption and disposition of glycylsarcosine in wild-type and Pept1 knockout mice. Drug Metab Dispos 2011; 39:2250-7. [PMID: 21880829 DOI: 10.1124/dmd.111.041087] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This study evaluated the in vivo absorption and disposition of glycylsarcosine (GlySar), after escalating oral doses, in wild-type and peptide transporter 1 (Pept1) knockout mice. [(3)H]GlySar was administered to mice at doses of 1, 10, 100, 1000, and 5000 nmol/g b.wt. Serial blood samples were obtained over 480 min, the plasma was harvested, and the area under the plasma concentration-time curve (AUC) was determined. It was observed that the GlySar AUC was 60, 45, and 30% lower in knockout than wild-type mice when evaluated over 2, 4, and 8 h, respectively (p < 0.01). Plasma levels of GlySar reached a plateau at 90 min in knockout mice and then rose to a second plateau at 240 min. In wild-type mice, the plasma levels rose continuously to reach a single plateau at 90 min. When partial AUC (0-120 min) was used as an indicator for rate of absorption, there was a 60% reduction in GlySar absorption rate in knockout mice compared with wild-type animals. Tissue distribution studies were also performed after 10 nmol/g oral doses of [(3)H]GlySar. When sampled 1 h after dosing, GlySar tissue concentrations were significantly lower in knockout versus wild-type mice and, with the exception of intestines, reflected differences in the systemic exposure of dipeptide between these two genotypes. Overall, PEPT1 ablation in mice resulted in significant reductions, in vivo, in the rate and extent of GlySar absorption. The AUC of GlySar was proportional to dose in both genotypes over 1 to 100 nmol/g, with minor decrements at the two highest doses.
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Affiliation(s)
- Dilara Jappar
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
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33
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Chen M, Sultan A, Cinar A, Yeruva S, Riederer B, Singh AK, Li J, Bonhagen J, Chen G, Yun C, Donowitz M, Hogema B, de Jonge H, Seidler U. Loss of PDZ-adaptor protein NHERF2 affects membrane localization and cGMP- and [Ca2+]- but not cAMP-dependent regulation of Na+/H+ exchanger 3 in murine intestine. J Physiol 2011; 588:5049-63. [PMID: 20962002 DOI: 10.1113/jphysiol.2010.198721] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Trafficking and regulation of the epithelial brush border membrane (BBM) Na+/H+ exchanger 3 (NHE3) in the intestine involves interaction with four different members of the NHERF family in a signal-dependent and possibly segment-specific fashion. The aim of this research was to study the role of NHERF2 (E3KARP) in intestinal NHE3 BBM localization and second messenger-mediated and receptor-mediated inhibition of NHE3. Immunolocalization of NHE3 in WT mice revealed predominant microvillar localization in jejunum and colon, a mixed distribution in the proximal ileum but localization near the terminal web in the distal ileum. The terminal web localization of NHE3 in the distal ileum correlated with reduced acid-activated NHE3 activity (fluorometrically assessed). NHERF2 ablation resulted in a shift of NHE3 to the microvilli and higher basal fluid absorption rates in the ileum, but no change in overall NHE3 protein or mRNA expression. Forskolin-induced NHE3 inhibition was preserved in the absence of NHERF2, whereas Ca2+ ionophore- or carbachol-mediated inhibition was abolished. Likewise, Escherichia coli heat stable enterotoxin peptide (STp) lost its inhibitory effect on intestinal NHE3. It is concluded that in native murine intestine, the NHE3 adaptor protein NHERF2 plays important roles in tethering NHE3 to a position near the terminal web and in second messenger inhibition of NHE3 in a signal- and segment-specific fashion, and is therefore an important regulator of intestinal fluid transport.
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Affiliation(s)
- Mingmin Chen
- Department of Gastroenterology, Hannover Medical School, Hannover 30625, Germany
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Nässl AM, Rubio-Aliaga I, Fenselau H, Marth MK, Kottra G, Daniel H. Amino acid absorption and homeostasis in mice lacking the intestinal peptide transporter PEPT1. Am J Physiol Gastrointest Liver Physiol 2011; 301:G128-37. [PMID: 21350187 DOI: 10.1152/ajpgi.00017.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal peptide transporter PEPT1 mediates the uptake of di- and tripeptides derived from dietary protein breakdown into epithelial cells. Whereas the transporter appears to be essential to compensate for the reduced amino acid delivery in patients with mutations in amino acid transporter genes, such as in cystinuria or Hartnup disease, its physiological role in overall amino acid absorption is still not known. To assess the quantitative importance of PEPT1 in overall amino acid absorption and metabolism, PEPT1-deficient mice were studied by using brush border membrane vesicles, everted gut sacs, and Ussing chambers, as well as by transcriptome and proteome analysis of intestinal tissue samples. Neither gene expression nor proteome profiling nor functional analysis revealed evidence for any compensatory changes in the levels and/or function of transporters for free amino acids in the intestine. However, most plasma amino acid levels were increased in Pept1(-/-) compared with Pept1(+/+) animals, suggesting that amino acid handling is altered. Plasma appearance rates of (15)N-labeled amino acids determined after intragastric administration of a low dose of protein remained unchanged, whereas administration of a large protein load via gavage revealed marked differences in plasma appearance of selected amino acids. PEPT1 seems, therefore, important for overall amino acid absorption only after high dietary protein intake when amino acid transport processes are saturated and PEPT1 can provide additional absorption capacity. Since renal amino acid excretion remained unchanged, elevated basal concentrations of plasma amino acids in PEPT1-deficient animals seem to arise mainly from alterations in hepatic amino acid metabolism.
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Affiliation(s)
- Anna-Maria Nässl
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany
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