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Rajendran A, Poncet N, Oparija-Rogenmozere L, Herzog B, Verrey F. Tissue-specific deletion of mouse basolateral uniporter LAT4 (Slc43a2) reveals its crucial role in small intestine and kidney amino acid transport. J Physiol 2020; 598:5109-5132. [PMID: 32841365 PMCID: PMC7693055 DOI: 10.1113/jp280234] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 08/19/2020] [Indexed: 01/16/2023] Open
Abstract
Key points LAT4 is a broadly expressed uniporter selective for essential branched chain amino acids, methionine and phenylalanine, which are involved in epithelial transport. Its global deletion leads to an early malnutrition‐like phenotype and death within 10 days after birth. Here, we tested the impact of deleting LAT4 selectively in the mouse intestine. This affected slightly the absorption of amino acids (AAs) and delayed gastrointestinal motility; however, it had no major phenotypic effect, even when combined with aromatic AA uniporter TAT1 knockout (KO). Conversely, kidney tubule‐selective deletion of LAT4 led to a substantial aminoaciduria that strongly increased under a high protein diet. Combining a partial tubular LAT4 deletion with TAT1 KO implicated their synergistic action on AA reabsorption. These results show that LAT4 plays an important role for kidney AA reabsorption, but that its functional role in intestinal AA absorption is largely dispensable.
Abstract Amino acid (AA) transporter LAT4 (Slc43a2) functions as facilitated diffusion uniporter for essential neutral AAs and is highly expressed at the basolateral membrane of small intestine (SI) and kidney tubule epithelia. Previously, we showed that LAT4 global knockout (KO) mice were born at the expected Mendelian ratio but died within 10 days. Their failure to gain weight and a severe malnutrition‐like phenotype contrasted with apparently normal feeding, suggesting a severe intestinal AA absorption defect. In the present study, using conditional global and tissue‐specific LAT4 KO mouse models, we nullified this hypothesis, demonstrating that the selective lack of intestinal LAT4 does not impair postnatal development, although it leads to an absorption defect accompanied by delayed gastrointestinal motility. Kidney tubule‐specific LAT4 KO led to a substantial aminoaciduria as a result of a reabsorption defect of AAs transported by LAT4 and of other AAs that are substrates of the antiporter LAT2, demonstrating, in vivo, the functional co‐operation of these two transporters. The major role played by basolateral uniporters in the kidney was further supported by the observation that, in mice lacking TAT1, another neutral AA uniporter, a partial LAT4 KO led to a synergistic increase of urinary AA loss. Surprisingly in the SI, the same combined KO induced no major effect, suggesting yet unknown compensatory mechanisms. Taken together, the lethal malnutrition‐like phenotype observed previously in LAT4 global KO pups is suggested to be the consequence of a combinatorial effect of LAT4 deletion in the SI, kidney and presumably other tissues. LAT4 is a broadly expressed uniporter selective for essential branched chain amino acids, methionine and phenylalanine, which are involved in epithelial transport. Its global deletion leads to an early malnutrition‐like phenotype and death within 10 days after birth. Here, we tested the impact of deleting LAT4 selectively in the mouse intestine. This affected slightly the absorption of amino acids (AAs) and delayed gastrointestinal motility; however, it had no major phenotypic effect, even when combined with aromatic AA uniporter TAT1 knockout (KO). Conversely, kidney tubule‐selective deletion of LAT4 led to a substantial aminoaciduria that strongly increased under a high protein diet. Combining a partial tubular LAT4 deletion with TAT1 KO implicated their synergistic action on AA reabsorption. These results show that LAT4 plays an important role for kidney AA reabsorption, but that its functional role in intestinal AA absorption is largely dispensable.
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Affiliation(s)
| | - Nadège Poncet
- Institute of Physiology University of Zurich, Zurich, Switzerland
| | | | - Brigitte Herzog
- Institute of Physiology University of Zurich, Zurich, Switzerland
| | - François Verrey
- Institute of Physiology University of Zurich, Zurich, Switzerland.,NCCR Kidney. CH, University of Zurich, Zurich, Switzerland
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Jordi J, Guggiana-Nilo D, Bolton AD, Prabha S, Ballotti K, Herrera K, Rennekamp AJ, Peterson RT, Lutz TA, Engert F. High-throughput screening for selective appetite modulators: A multibehavioral and translational drug discovery strategy. SCIENCE ADVANCES 2018; 4:eaav1966. [PMID: 30402545 PMCID: PMC6209392 DOI: 10.1126/sciadv.aav1966] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 09/27/2018] [Indexed: 05/19/2023]
Abstract
How appetite is modulated by physiological, contextual, or pharmacological influence is still unclear. Specifically, the discovery of appetite modulators is compromised by the abundance of side effects that usually limit in vivo drug action. We set out to identify neuroactive drugs that trigger only their intended single behavioral change, which would provide great therapeutic advantages. To identify these ideal bioactive small molecules, we quantified the impact of more than 10,000 compounds on an extended series of different larval zebrafish behaviors using an in vivo imaging strategy. Known appetite-modulating drugs altered feeding and a pleiotropy of behaviors. Using this multibehavioral strategy as an active filter for behavioral side effects, we identified previously unidentified compounds that selectively increased or reduced food intake by more than 50%. The general applicability of this strategy is shown by validation in mice. Mechanistically, most candidate compounds were independent of the main neurotransmitter systems. In addition, we identified compounds with multibehavioral impact, and correlational comparison of these profiles with those of known drugs allowed for the prediction of their mechanism of action. Our results illustrate an unbiased and translational drug discovery strategy for ideal psychoactive compounds and identified selective appetite modulators in two vertebrate species.
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Affiliation(s)
- Josua Jordi
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Institute of Veterinary Physiology, University of Zurich, Switzerland
- Corresponding author. (J.J.); (F.E.)
| | - Drago Guggiana-Nilo
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Andrew D Bolton
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Srishti Prabha
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Kaitlyn Ballotti
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Kristian Herrera
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Andrew J. Rennekamp
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - Randall T. Peterson
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - Thomas A. Lutz
- Institute of Veterinary Physiology, University of Zurich, Switzerland
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Corresponding author. (J.J.); (F.E.)
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Ullrich SS, Fitzgerald PCE, Giesbertz P, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of Intragastric Administration of Tryptophan on the Blood Glucose Response to a Nutrient Drink and Energy Intake, in Lean and Obese Men. Nutrients 2018; 10:nu10040463. [PMID: 29642492 PMCID: PMC5946248 DOI: 10.3390/nu10040463] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 02/07/2023] Open
Abstract
Tryptophan stimulates plasma cholecystokinin and pyloric pressures, both of which slow gastric emptying. Gastric emptying regulates postprandial blood glucose. Tryptophan has been reported to decrease energy intake. We investigated the effects of intragastric tryptophan on the glycaemic response to, and gastric emptying of, a mixed-nutrient drink, and subsequent energy intake. Lean and obese participants (n = 16 each) received intragastric infusions of 1.5 g ("Trp-1.5g") or 3.0 g ("Trp-3.0g") tryptophan, or control, and 15 min later consumed a mixed-nutrient drink (56 g carbohydrates). Gastric emptying (13C-acetate breath-test), blood glucose, plasma C-peptide, glucagon, cholecystokinin and tryptophan concentrations were measured (t = 0-60 min). Energy intake was assessed between t = 60-90 min. In lean individuals, Trp-3.0g, but not Trp-1.5g, slowed gastric emptying, reduced C-peptideAUC and increased glucagonAUC (all P < 0.05), but did not significantly decrease the blood glucose response to the drink, stimulate cholecystokinin or reduce mean energy intake, compared with control. In obese individuals, Trp-3.0g, but not Trp-1.5g, tended to slow gastric emptying (P = 0.091), did not affect C-peptideAUC, increased glucagonAUC (P < 0.001) and lowered blood glucose at t = 30 min (P < 0.05), and did not affect cholecystokinin or mean energy intake. In obese individuals, intragastrically administered tryptophan may reduce postprandial blood glucose by slowing gastric emptying; the lack of effect on mean energy intake requires further investigation.
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Affiliation(s)
- Sina S Ullrich
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Penelope C E Fitzgerald
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Pieter Giesbertz
- Department of Nutritional Physiology, Technical University of Munich, Gregor-Mendel Strasse 2, 85354 Freising, Germany.
| | - Robert E Steinert
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland.
| | - Michael Horowitz
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Christine Feinle-Bisset
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
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Colón-Useche S, González-Álvarez I, Mangas-Sanjuan V, González-Álvarez M, Pastoriza P, Molina-Martínez I, Bermejo M, García-Arieta A. Investigating the Discriminatory Power of BCS-Biowaiver in Vitro Methodology to Detect Bioavailability Differences between Immediate Release Products Containing a Class I Drug. Mol Pharm 2015; 12:3167-74. [PMID: 26287948 DOI: 10.1021/acs.molpharmaceut.5b00076] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this work is to investigate the discriminatory power of the Biopharmaceutics Classification System (BCS)-biowaiver in vitro methodology, i.e., to investigate if a BCS-biowaiver approach would have detected the Cmax differences observed between two zolpidem tablets and to identify the cause of the in vivo difference. Several dissolution conditions were tested with three zolpidem formulations: the reference (Stilnox), a bioequivalent formulation (BE), and a nonbioequivalent formulation (N-BE). Zolpidem is highly soluble at pH 1.2, 4.5, and 6.8. Its permeability in Caco-2 cells is higher than that of metoprolol and its transport mechanism is passive diffusion. None of the excipients (alone or in combination) showed any effect on permeability. All formulations dissolved more than 85% in 15 min in the paddle apparatus at 50 rpm in all dissolution media. However, at 30 rpm the nonbioequivalent formulation exhibited a slower dissolution rate. A slower gastric emptying rate was also observed in rats for the nonbioequivalent formulation. A slower disintegration and dissolution or a delay in gastric emptying might explain the Cmax infra-bioavailability for a highly permeable drug with short half-life. The BCS-biowaiver approach would have declared bioequivalence, although the in vivo study was not conclusive but detected a 14% mean difference in Cmax that precluded the bioequivalence demonstration. Nonetheless, these findings suggest that a slower dissolution rate is more discriminatory and that rotation speeds higher than 50 rpm should not be used in BCS-biowaivers, even if a coning effect occurs.
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Affiliation(s)
- Sarin Colón-Useche
- Engineering: Pharmacokinetics and Pharmaceutical Technology Area, Miguel Hernandez University , 03550 Alicante, Spain.,Pharmacokinetics and Pharmaceutical Technology, Complutense University of Madrid , 28040 Madrid, Spain.,Analysis and Control Department, University of Los Andes , Mérida, Venezuela
| | - Isabel González-Álvarez
- Engineering: Pharmacokinetics and Pharmaceutical Technology Area, Miguel Hernandez University , 03550 Alicante, Spain
| | - Victor Mangas-Sanjuan
- Engineering: Pharmacokinetics and Pharmaceutical Technology Area, Miguel Hernandez University , 03550 Alicante, Spain
| | - Marta González-Álvarez
- Engineering: Pharmacokinetics and Pharmaceutical Technology Area, Miguel Hernandez University , 03550 Alicante, Spain
| | - Pilar Pastoriza
- Pharmacokinetics and Pharmaceutical Technology, Complutense University of Madrid , 28040 Madrid, Spain
| | - Irene Molina-Martínez
- Pharmacokinetics and Pharmaceutical Technology, Complutense University of Madrid , 28040 Madrid, Spain
| | - Marival Bermejo
- Engineering: Pharmacokinetics and Pharmaceutical Technology Area, Miguel Hernandez University , 03550 Alicante, Spain
| | - Alfredo García-Arieta
- Service on Pharmacokinetics and Generic Medicines, Division of Pharmacology and Clinical Evaluation, Department of Human Use Medicines, Spanish Agency for Medicines and Health Care Products , 28022 Madrid, Spain
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Jordi J, Guggiana-Nilo D, Soucy E, Song EY, Lei Wee C, Engert F. A high-throughput assay for quantifying appetite and digestive dynamics. Am J Physiol Regul Integr Comp Physiol 2015; 309:R345-57. [PMID: 26108871 DOI: 10.1152/ajpregu.00225.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 06/16/2015] [Indexed: 01/23/2023]
Abstract
Food intake and digestion are vital functions, and their dysregulation is fundamental for many human diseases. Current methods do not support their dynamic quantification on large scales in unrestrained vertebrates. Here, we combine an infrared macroscope with fluorescently labeled food to quantify feeding behavior and intestinal nutrient metabolism with high temporal resolution, sensitivity, and throughput in naturally behaving zebrafish larvae. Using this method and rate-based modeling, we demonstrate that zebrafish larvae match nutrient intake to their bodily demand and that larvae adjust their digestion rate, according to the ingested meal size. Such adaptive feedback mechanisms make this model system amenable to identify potential chemical modulators. As proof of concept, we demonstrate that nicotine, l-lysine, ghrelin, and insulin have analogous impact on food intake as in mammals. Consequently, the method presented here will promote large-scale translational research of food intake and digestive function in a naturally behaving vertebrate.
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Affiliation(s)
- Josua Jordi
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and
| | - Drago Guggiana-Nilo
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and Committee for Higher Degrees in Biophysics, Harvard University, Cambridge, Massachusetts
| | - Edward Soucy
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and
| | - Erin Yue Song
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and
| | - Caroline Lei Wee
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts; and
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