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Küng CJ, Daryadel A, Fuente R, Haykir B, de Angelis MH, Hernando N, Rubio-Aliaga I, Wagner CA. A novel mouse model for familial hypocalciuric hypercalcemia (FHH1) reveals PTH-dependent and independent CaSR defects. Pflugers Arch 2024; 476:833-845. [PMID: 38386045 PMCID: PMC11033242 DOI: 10.1007/s00424-024-02927-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/11/2024] [Accepted: 02/12/2024] [Indexed: 02/23/2024]
Abstract
The Calcium-sensing receptor (CaSR) senses extracellular calcium, regulates parathyroid hormone (PTH) secretion, and has additional functions in various organs related to systemic and local calcium and mineral homeostasis. Familial hypocalciuric hypercalcemia type I (FHH1) is caused by heterozygous loss-of-function mutations in the CaSR gene, and is characterized by the combination of hypercalcemia, hypocalciuria, normal to elevated PTH, and facultatively hypermagnesemia and mild bone mineralization defects. To date, only heterozygous Casr null mice have been available as model for FHH1. Here we present a novel mouse FHH1 model identified in a large ENU-screen that carries an c.2579 T > A (p.Ile859Asn) variant in the Casr gene (CasrBCH002 mice). In order to dissect direct effects of the genetic variant from PTH-dependent effects, we crossed CasrBCH002 mice with PTH deficient mice. Heterozygous CasrBCH002 mice were fertile, had normal growth and body weight, were hypercalcemic and hypermagnesemic with inappropriately normal PTH levels and urinary calcium excretion replicating some features of FHH1. Hypercalcemia and hypermagnesemia were independent from PTH and correlated with higher expression of claudin 16 and 19 in kidneys. Likewise, reduced expression of the renal TRPM6 channel in CasrBCH002 mice was not dependent on PTH. In bone, mutations in Casr rescued the bone phenotype observed in Pth null mice by increasing osteoclast numbers and improving the columnar pattern of chondrocytes in the growth zone. In summary, CasrBCH002 mice represent a new model to study FHH1 and our results indicate that only a part of the phenotype is driven by PTH.
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Affiliation(s)
- Catharina J Küng
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Arezoo Daryadel
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Rocio Fuente
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
- Department of Morphology and Cellular Biology, University of Oviedo, Oviedo, Spain
| | - Betül Haykir
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Martin Hrabĕ de Angelis
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Lehrstuhl Für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
- Member of German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Nati Hernando
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
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Daryadel A, Küng CJ, Haykir B, Sabrautzki S, de Angelis MH, Hernando N, Rubio-Aliaga I, Wagner CA. The calcium-sensing receptor has only a parathyroid hormone-dependent role in the acute response of renal phosphate transporters to phosphate intake. Am J Physiol Renal Physiol 2024; 326:F792-F801. [PMID: 38545651 DOI: 10.1152/ajprenal.00009.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 05/04/2024] Open
Abstract
The kidney controls systemic inorganic phosphate (Pi) levels by adapting reabsorption to Pi intake. Renal Pi reabsorption is mostly mediated by sodium-phosphate cotransporters NaPi-IIa (SLC34A1) and NaPi-IIc (SLC34A3) that are tightly controlled by various hormones including parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23). PTH and FGF23 rise in response to Pi intake and decrease NaPi-IIa and NaPi-IIc brush border membrane abundance enhancing phosphaturia. Phosphaturia and transporter regulation occurs even in the absence of PTH and FGF23 signaling. The calcium-sensing receptor (CaSR) regulates PTH and FGF23 secretion, and may also directly affect renal Pi handling. Here, we combined pharmacological and genetic approaches to examine the role of the CaSR in the acute phosphaturic response to Pi loading. Animals pretreated with the calcimimetic cinacalcet were hyperphosphatemic, had blunted PTH levels upon Pi administration, a reduced Pi-induced phosphaturia, and no Pi-induced NaPi-IIa downregulation. The calcilytic NPS-2143 exaggerated the PTH response to Pi loading but did not abolish Pi-induced downregulation of NaPi-IIa. In mice with a dominant inactivating mutation in the Casr (CasrBCH002), baseline NaPi-IIa expression was higher, whereas downregulation of transporter expression was blunted in double CasrBCH002/PTH knockout (KO) transgenic animals. Thus, in response to an acute Pi load, acute modulation of the CaSR affects the endocrine and renal response, whereas chronic genetic inactivation, displays only subtle differences in the downregulation of NaPi-IIa and NaPi-IIc renal expression. We did not find evidence that the CaSR impacts on the acute renal response to oral Pi loading beyond its role in regulating PTH secretion.NEW & NOTEWORTHY Consumption of phosphate-rich diets causes an adaptive response of the body leading to the urinary excretion of phosphate. The underlying mechanisms are still poorly understood. Here, we examined the role of the calcium-sensing receptor (CaSR) that senses both calcium and phosphate. We confirmed that the receptor increases the secretion of parathyroid hormone involved in stimulating urinary phosphate excretion. However, we did not find any evidence for a role of the receptor beyond this function.
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Affiliation(s)
- Arezoo Daryadel
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Catharina J Küng
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Betül Haykir
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Sibylle Sabrautzki
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabĕ de Angelis
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising, Germany
- Member of German Center for Diabetes Research, Neuherberg, Germany
| | - Nati Hernando
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | | | - Carsten A Wagner
- Institute of Physiology, University of Zürich, Zürich, Switzerland
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Radvanyi Z, Yoo EJ, Kandasamy P, Salas-Bastos A, Monnerat S, Refardt J, Christ-Crain M, Hayashi H, Kondo Y, Jantsch J, Rubio-Aliaga I, Sommer L, Wagner CA, Hediger MA, Kwon HM, Loffing J, Pathare G. Extracellular sodium regulates fibroblast growth factor 23 (FGF23) formation. J Biol Chem 2024; 300:105480. [PMID: 37992803 PMCID: PMC10770535 DOI: 10.1016/j.jbc.2023.105480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 10/30/2023] [Accepted: 11/16/2023] [Indexed: 11/24/2023] Open
Abstract
The bone-derived hormone fibroblast growth factor-23 (FGF23) has recently received much attention due to its association with chronic kidney disease and cardiovascular disease progression. Extracellular sodium concentration ([Na+]) plays a significant role in bone metabolism. Hyponatremia (lower serum [Na+]) has recently been shown to be independently associated with FGF23 levels in patients with chronic systolic heart failure. However, nothing is known about the direct impact of [Na+] on FGF23 production. Here, we show that an elevated [Na+] (+20 mM) suppressed FGF23 formation, whereas low [Na+] (-20 mM) increased FGF23 synthesis in the osteoblast-like cell lines UMR-106 and MC3T3-E1. Similar bidirectional changes in FGF23 abundance were observed when osmolality was altered by mannitol but not by urea, suggesting a role of tonicity in FGF23 formation. Moreover, these changes in FGF23 were inversely proportional to the expression of NFAT5 (nuclear factor of activated T cells-5), a transcription factor responsible for tonicity-mediated cellular adaptations. Furthermore, arginine vasopressin, which is often responsible for hyponatremia, did not affect FGF23 production. Next, we performed a comprehensive and unbiased RNA-seq analysis of UMR-106 cells exposed to low versus high [Na+], which revealed several novel genes involved in cellular adaptation to altered tonicity. Additional analysis of cells with Crisp-Cas9-mediated NFAT5 deletion indicated that NFAT5 controls numerous genes associated with FGF23 synthesis, thereby confirming its role in [Na+]-mediated FGF23 regulation. In line with these in vitro observations, we found that hyponatremia patients have higher FGF23 levels. Our results suggest that [Na+] is a critical regulator of FGF23 synthesis.
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Affiliation(s)
- Zsuzsa Radvanyi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland
| | - Eun Jin Yoo
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Palanivel Kandasamy
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Bern, Switzerland
| | | | - Sophie Monnerat
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Julie Refardt
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Mirjam Christ-Crain
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Himeka Hayashi
- Department of Animal Sciences, Teikyo University of Science, Yamanashi, Japan
| | - Yasuhiko Kondo
- Department of Animal Sciences, Teikyo University of Science, Yamanashi, Japan
| | - Jonathan Jantsch
- Institute of Clinical Microbiology and Hygiene, University Hospital of Regensburg and University of Regensburg, Regensburg, Germany; Institute for Medical Microbiology, Immunology, and Hygiene, and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Isabel Rubio-Aliaga
- Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Lukas Sommer
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Matthias A Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Bern, Switzerland
| | - Hyug Moo Kwon
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland
| | - Ganesh Pathare
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland.
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Egli-Spichtig D, Hamid AK, Arroyo EMP, Ketteler M, Wiecek A, Rosenkranz AR, Pasch A, Lorenz H, Hellmann B, Karus M, Ammer R, Rubio-Aliaga I, Wagner CA. Intact FGF23 predicts serum phosphate improvement after combined nicotinamide and phosphate binder treatment in hemodialysis patients. Clin Kidney J 2023; 16:1622-1633. [PMID: 37779856 PMCID: PMC10539220 DOI: 10.1093/ckj/sfad040] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 10/03/2023] Open
Abstract
Background Hyperphosphatemia is associated with increased mortality and cardiovascular morbidity of end-stage kidney failure (ESKF) patients. Managing serum phosphate in ESKF patients is challenging and mostly based on limiting intestinal phosphate absorption with low phosphate diets and phosphate binders (PB). In a multi-centric, double-blinded, placebo-controlled study cohort of maintenance hemodialysis patients with hyperphosphatemia, we demonstrated the efficacy of nicotinamide modified release (NAMR) formulation treatment in addition to standard PB therapy in decreasing serum phosphate. Here we aimed to assess the relationship between phosphate, FGF23, inflammation and iron metabolism in this cohort. Methods We measured the plasma concentrations of intact fibroblast growth factor 23 (iFGF23) and selected proinflammatory cytokines at baseline and Week 12 after initiating treatment. Results We observed a strong correlation between iFGF23 and cFGF23 (C-terminal fragment plus iFGF23). We identified iFGF23 as a better predictor of changes in serum phosphate induced by NAMR and PB treatment compared with cFGF23. Recursive partitioning revealed at baseline and Week 12, that iFGF23 and cFGF23 together with T50 propensity were the most important predictors of serum phosphate, whereas intact parathyroid hormone (iPTH) played a minor role in this model. Furthermore, we found serum phosphate and iPTH as the best predictors of iFGF23 and cFGF23. Sex, age, body mass index, and markers of inflammation and iron metabolism had only a minor impact in predicting FGF23. Conclusion Lowering serum phosphate in ESKF patients may depend highly on iFGF23 which is correlated to cFGF23 levels. Serum phosphate was the most important predictor of plasma FGF23 in this ESKF cohort.
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Affiliation(s)
- Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Markus Ketteler
- Robert Bosch Hospital, Department of General Internal Medicine and Nephrology, Stuttgart, Germany
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice, Poland
| | - Alexander R Rosenkranz
- Division of Nephrology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Andreas Pasch
- Calciscon AG, 2503 Biel, Switzerland
- Department of Nephrology, Lindenhofspital, 3012 Bern, Switzerland
- Department of Physiology and Pathophysiology, Johannes Kepler University Linz, Linz, Austria
| | - Horst Lorenz
- Buero fuer Biometrie und Statistik, Neuberg, Germany
| | | | - Michael Karus
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
| | - Richard Ammer
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
- Department of Medicine D, Division of General Internal Medicine, Nephrology and Rheumatology, University Hospital of Münster, Münster, Germany
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
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Fuente R, Pastor-Arroyo EM, Gehring N, Oro Carbajosa P, Alonso-Durán L, Zderic I, Tapia-Dean J, Hamid AK, Bettoni C, Santos F, Wagner CA, Rubio-Aliaga I. Blocking FGF23 signaling improves the growth plate of mice with X-linked hypophosphatemia. J Endocrinol 2023; 259:e230025. [PMID: 37439399 DOI: 10.1530/joe-23-0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 07/12/2023] [Indexed: 07/14/2023]
Abstract
Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone. X-linked hypophosphatemia (XLH) is the most prevalent inherited phosphate wasting disorder due to mutations in the PHEX gene, which cause elevated circulating FGF23 levels. Clinically, it is characterized by growth impairment and defective mineralization of bones and teeth. Treatment of XLH is challenging. Since 2018, neutralizing antibodies against FGF23 have dramatically improved the therapy of XLH patients, although not all patients fully respond to the treatment, and it is very costly. C-terminal fragments of FGF23 have recently emerged as blockers of intact FGF23 signaling. Here, we analyzed the effect on growth and bone of a short 26 residues long C-terminal FGF23 (cFGF23) fragment and two N-acetylated and C-amidated cFGF23 peptides using young XLH mice (Phex C733RMhda mice). Although no major changes in blood parameters were observed after 7 days of treatment with these peptides, bone length and growth plate structure improved. The modified peptides accelerated the growth rate probably by improving growth plate structure and dynamics. The processes of chondrocyte proliferation, death, hypertrophy, and the cartilaginous composition in the growth plate were partially improved in young treated XLH mice. In conclusion, these findings contribute to understand the role of FGF23 signaling in growth plate metabolism and show that this may occur despite continuous hypophosphatemia.
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Affiliation(s)
- Rocío Fuente
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
- Division of Pediatrics, University of Oviedo, Oviedo, Spain
- Department of Pediatrics, Hospital Universitario Central, Oviedo, Spain
| | - Eva-Maria Pastor-Arroyo
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
| | | | | | - Ivan Zderic
- AO Research Institute Davos, AO Foundation, Clavadelerstrasse, Davos Platz, Switzerland
| | - James Tapia-Dean
- Department of Pediatrics, Hospital Universitario Central, Oviedo, Spain
| | - Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
| | - Fernando Santos
- Division of Pediatrics, University of Oviedo, Oviedo, Spain
- Department of Pediatrics, Hospital Universitario Central, Oviedo, Spain
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NNCR Kidney, Zurich, CH, Switzerland
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Abstract
Phosphate is essential in living organisms and its blood levels are regulated by a complex network involving the kidneys, intestine, parathyroid glands, and the skeleton. The crosstalk between these organs is executed primarily by three hormones, calcitriol, parathyroid hormone, and fibroblast growth factor 23. Largely due to a higher intake of ultraprocessed foods, dietary phosphate intake has increased in the last decades. The average intake is now about twice the recommended dietary allowance. Studies investigating the side effect of chronic high dietary phosphate intake suffer from incomplete dietary phosphate assessment and, therefore, often make data interpretation difficult. Renal excretion is quickly adapted to acute and chronic phosphate intake. However, at the high ends of dietary intake, renal adaptation, even in pre-existing normal kidney function, apparently is not perfect. Experimental intervention studies suggest that chronic excess of dietary phosphate can result in sustained higher blood phosphate leading to hyperphosphatemia. Evidence exists that the price of the homeostatic response (phosphaturia in response to phosphate loading/hyperphosphatemia) is an increased risk for declining kidney function, partly due by intraluminal/tubular calcium phosphate particles that provoke renal inflammation. High dietary phosphate intake and hyperphosphatemia are progression factors for declining kidney function and are associated with higher cardiovascular disease and mortality risk. This is best established for pre-existing chronic kidney disease, but epidemiological and experimental data strongly suggest that this holds true for subjects with normal renal function as well. Here, we review the latest advances in phosphate intake and kidney function decline.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Institute of Physiology, National Center of Competence in Research NCCR Kidney.CH, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Reto Krapf
- Synlab Suisse, 6002, Lucerne, Switzerland
- Department of Medicine, University of Basel, 4056, Basel, Switzerland
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Ugrica M, Gehring N, Giesbertz P, Pastor-Arroyo EM, Daniel H, Wagner CA, Rubio-Aliaga I. Chronic High Phosphate Intake in Mice Affects Macronutrient Utilization and Body Composition. Mol Nutr Food Res 2022; 66:e2100949. [PMID: 35194921 DOI: 10.1002/mnfr.202100949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/04/2022] [Indexed: 11/11/2022]
Abstract
SCOPE In the last decades, dietary phosphate intake has increased due to a higher consumption of processed food. This higher intake has an impact on body composition and health state. Recently, we found that a high chronic phosphate diet leads to no major renal alterations, but negatively affects parameters of bone health probably due to the chronic acid load. Here we assessed the effect of high phosphate consumption on parameters of energy metabolism. METHODS AND RESULTS Healthy mature adult mice were fed for 1 year or four months with either a standard (0.6 % w/w) or a high phosphate (1.2 % w/w) diet. Males and females of two different genetic backgrounds were investigated. Mice fed the high phosphate diet showed an attenuated body-weight gain, lower respiratory exchange ratio, decreased body fat mass and increased lean-to-fat mass ratio. Moreover, the high phosphate diet led to fasting hypoglycemia with no differences in the glucose response to an oral glucose tolerance test. Triglycerides and cholesterol in blood were similar independently of dietary phosphate content. However, 1-methylhistidine was lower in animals fed a chronic high phosphate intake. CONCLUSIONS High phosphate diet attenuates body weight gain, but induces hypoglycaemia and may alter muscle homeostasis. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Marko Ugrica
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney, Zurich, 8057, Switzerland
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney, Zurich, 8057, Switzerland
| | - Pieter Giesbertz
- Nutritional Physiology, Technical University of Munich, Freising, 85354, Germany
| | - Eva-Maria Pastor-Arroyo
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney, Zurich, 8057, Switzerland
| | - Hannelore Daniel
- Nutritional Physiology, Technical University of Munich, Freising, 85354, Germany
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney, Zurich, 8057, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney, Zurich, 8057, Switzerland
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Gehring N, Bettoni C, Wagner CA, Rubio-Aliaga I. Jak1/Stat3 Activation Alters Phosphate Metabolism Independently of Sex and Extracellular Phosphate Levels. Kidney Blood Press Res 2021; 46:714-722. [PMID: 34515136 DOI: 10.1159/000518488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/12/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Phosphate homeostasis is regulated by a complex network involving the parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and calcitriol acting on several organs including the kidney, intestine, bone, and parathyroid gland. Previously, we showed that activation of the Janus kinase 1 (Jak1)-signal transducer and activator of transcription 3 (Stat3) signaling pathway leads to altered mineral metabolism with higher FGF23 levels, lower PTH, and higher calcitriol levels. Here, we investigated if there are sex differences in the role of Jak1/Stat3 signaling pathway on phosphate metabolism and if this pathway is sensitive to extracellular phosphate alterations. METHODS We used a mouse model (Jak1S645P+/-) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans and analyzed the impact of sex on mineral metabolism parameters. Furthermore, we challenged Jak1S645P+/- male and female mice with a high (1.2% w/w) and low (0.1% w/w) phosphate diet and a diet with phosphate with organic origin with lower bioavailability. RESULTS Female mice, as male mice, showed higher intact FGF23 levels but no phosphaturia, and higher calcitriol and lower PTH levels in plasma. A phosphate challenge did not alter the effect of Jak1/Stat3 activation on phosphate metabolism for both genders. However, under a low phosphate diet or a diet with lower phosphate availability, the animals showed a tendency to develop hypophosphatemia. Moreover, male and female mice showed similar phosphate metabolism parameters. The only exception was higher PTH levels in male mice than those in females. DISCUSSION/CONCLUSION Sex and extracellular phosphate levels do not affect the impact of Jak1/Stat3 activation on phosphate metabolism.
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Affiliation(s)
- Nicole Gehring
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
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Fuente R, Gehring N, Bettoni C, Gil-Peña H, Alonso-Durán L, Michalke B, Santos F, Wagner CA, Rubio-Aliaga I. Systemic Jak1 activation causes extrarenal calcitriol production and skeletal alterations provoking stunted growth. FASEB J 2021; 35:e21721. [PMID: 34118090 DOI: 10.1096/fj.202100587r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/12/2021] [Accepted: 05/20/2021] [Indexed: 02/06/2023]
Abstract
Mineral homeostasis is regulated by a complex network involving endocrine actions by calcitriol, parathyroid hormone (PTH), and FGF23 on several organs including kidney, intestine, and bone. Alterations of mineral homeostasis are found in chronic kidney disease and other systemic disorders. The interplay between the immune system and the skeletal system is not fully understood, but cytokines play a major role in modulating calcitriol production and function. One of the main cellular signaling pathways mediating cytokine function is the Janus kinase (JAK)--signal transducer and activator of transcription (STAT) pathway. Here, we used a mouse model (Jak1S645P+/- ) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans, and shows altered mineral metabolism, with higher fibroblast growth factor 23 (FGF23) levels, lower PTH levels, and higher calcitriol levels. The higher calcitriol levels are probably due to extrarenal calcitriol production. Furthermore, systemic Jak1/Stat3 activation led to growth impairment and skeletal alterations. The growth plate in long bones showed decreased chondrocyte proliferation rates and reduced height of terminal chondrocytes. Furthermore, we demonstrate that Jak1 is also involved in bone remodeling early in life. Jak1S645P+/- animals have decreased bone and cortical volume, imbalanced bone remodeling, reduced MAP kinase signaling, and local inflammation. In conclusion, Jak1 plays a major role in bone health probably both, directly and systemically by regulating mineral homeostasis. Understanding the role of this signaling pathway will contribute to a better knowledge in bone growth and in mineral physiology, and to the development of selective Jak inhibitors as osteoprotective agents.
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Affiliation(s)
- Rocío Fuente
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.,Division of Pediatrics, University of Oviedo, Oviedo, Spain
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | | | | | - Bernhard Michalke
- Department of Environmental Science, Research Unit Analytical, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Fernando Santos
- Division of Pediatrics, University of Oviedo, Oviedo, Spain.,Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
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10
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Ugrica M, Bettoni C, Bourgeois S, Daryadel A, Pastor-Arroyo EM, Gehring N, Hernando N, Wagner CA, Rubio-Aliaga I. A chronic high phosphate intake in mice is detrimental for bone health without major renal alterations. Nephrol Dial Transplant 2021; 36:gfab015. [PMID: 33515264 DOI: 10.1093/ndt/gfab015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Phosphate intake has increased in the last decades due to a higher consumption of processed foods. This higher intake is detrimental for patients with chronic kidney disease, increasing mortality and cardiovascular disease risk and accelerating kidney dysfunction. Whether a chronic high phosphate diet is also detrimental for the healthy population is still under debate. METHODS We fed healthy mature adult mice over a period of one year with either a high (1.2% w/w) or a standard (0.6% w/w) phosphate diet, and investigated the impact of a high phosphate diet on mineral homeostasis, kidney function and bone health. RESULTS The high phosphate diet increased plasma phosphate, parathyroid hormone (PTH) and calcitriol levels, with no change in fibroblast growth factor 23 levels. Urinary phosphate, calcium and ammonium excretion were increased. Measured glomerular filtration rate was apparently unaffected, while blood urea was lower and urea clearance was higher in animals fed the high phosphate diet. No change was observed in plasma creatinine levels. Blood and urinary pH were more acidic paralleled by higher bone resorption observed in animals fed a high phosphate diet. Total and cortical bone mineral density was lower in animals fed a high phosphate diet and this effect is independent of the higher PTH levels observed. CONCLUSIONS A chronic high phosphate intake did not cause major renal alterations, but affected negatively bone health, increasing bone resorption and decreasing bone mineral density.
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Affiliation(s)
- Marko Ugrica
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Arezoo Daryadel
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Eva-Maria Pastor-Arroyo
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Nati Hernando
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
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Abstract
<b><i>Background:</i></b> The aging population is increasing rapidly, much faster than our understanding on how to promote healthy aging free of multimorbidities. The aging kidney shows a decline in its function. Whether this decline is preventable or physiological is still debated. Main risks factors for developing CKD are aging common comorbidites, such as hypertension, diabetes, and obesity. Phosphate is vital for our organism, but it is also present in a great variety of food products as food additive and preservative. Due to the higher consumption of processed food in the last century, concern has arisen if a chronic high consumption of phosphate may be toxic impacting on healthy aging. <b><i>Summary:</i></b> Several studies show an association between higher serum phosphate levels and a higher risk of overall mortality and cardiovascular disease. Moreover, higher phosphate levels also worsen CKD progression and may contribute to renal dysfunction in healthy individuals. Acute high phosphate intake is rare but can cause acute kidney injury. Yet, the question if controlling phosphate intake may modulate serum phosphate concentrations remains unanswered, as assessment of phosphate intake is still a difficult task. Phosphate consumption estimations by dietary recalls are largely underestimated, especially in populations groups consuming high amount of processed food. <b><i>Key Message:</i></b> A healthy diet with phosphate source from food may contribute to promote healthy aging and longevity.
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Wagner CA, Rubio-Aliaga I, Egli-Spichtig D. Fibroblast growth factor 23 in chronic kidney disease: what is its role in cardiovascular disease? Nephrol Dial Transplant 2019; 34:1986-1990. [PMID: 30903187 DOI: 10.1093/ndt/gfz044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 02/10/2019] [Indexed: 11/14/2022] Open
Affiliation(s)
- Carsten A Wagner
- National Center of Competence in Research Kidney, CH, Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- National Center of Competence in Research Kidney, CH, Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Daniela Egli-Spichtig
- National Center of Competence in Research Kidney, CH, Institute of Physiology, University of Zurich, Zurich, Switzerland
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Fuente R, Gil-Peña H, Claramunt-Taberner D, Hernández-Frías O, Fernández-Iglesias Á, Alonso-Durán L, Rodríguez-Rubio E, Hermida-Prado F, Anes-González G, Rubio-Aliaga I, Wagner C, Santos F. MAPK inhibition and growth hormone: a promising therapy in XLH. FASEB J 2019; 33:8349-8362. [DOI: 10.1096/fj.201802007r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Rocío Fuente
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
- Department of Developmental BiologyHarvard School of Dental MedicineHarvard University Boston Massachusetts USA
| | - Helena Gil-Peña
- Department of PediatricsHospital Universitario Central de Asturias Oviedo Spain
| | - Débora Claramunt-Taberner
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
| | - Olaya Hernández-Frías
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
| | - Ángela Fernández-Iglesias
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
| | - Laura Alonso-Durán
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
| | - Enrique Rodríguez-Rubio
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
| | - Francisco Hermida-Prado
- Department of OtorhinolaryngologyHospital Universitario Central de AsturiasInstituto Universitario de Oncología del Principado de Asturias Oviedo Spain
| | | | - Isabel Rubio-Aliaga
- Kidney and Acid-Base Physiology GroupInstitute of PhysiologyUniversity of Zurich Zurich Switzerland
| | - Carsten Wagner
- Kidney and Acid-Base Physiology GroupInstitute of PhysiologyUniversity of Zurich Zurich Switzerland
| | - Fernando Santos
- Division of PediatricsDepartment of MedicineFaculty of Medicine and Health SciencesUniversity of Oviedo Oviedo Spain
- Department of PediatricsHospital Universitario Central de Asturias Oviedo Spain
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14
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Wagner CA, Rubio-Aliaga I, Hernando N. Renal phosphate handling and inherited disorders of phosphate reabsorption: an update. Pediatr Nephrol 2019; 34:549-559. [PMID: 29275531 DOI: 10.1007/s00467-017-3873-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 01/12/2023]
Abstract
Renal phosphate handling critically determines plasma phosphate and whole body phosphate levels. Filtered phosphate is mostly reabsorbed by Na+-dependent phosphate transporters located in the brush border membrane of the proximal tubule: NaPi-IIa (SLC34A1), NaPi-IIc (SLC34A3), and Pit-2 (SLC20A2). Here we review new evidence for the role and relevance of these transporters in inherited disorders of renal phosphate handling. The importance of NaPi-IIa and NaPi-IIc for renal phosphate reabsorption and mineral homeostasis has been highlighted by the identification of mutations in these transporters in a subset of patients with infantile idiopathic hypercalcemia and patients with hereditary hypophosphatemic rickets with hypercalciuria. Both diseases are characterized by disturbed calcium homeostasis secondary to elevated 1,25-(OH)2 vitamin D3 as a consequence of hypophosphatemia. In vitro analysis of mutated NaPi-IIa or NaPi-IIc transporters suggests defective trafficking underlying disease in most cases. Monoallelic pathogenic mutations in both SLC34A1 and SLC34A3 appear to be very frequent in the general population and have been associated with kidney stones. Consistent with these findings, results from genome-wide association studies indicate that variants in SLC34A1 are associated with a higher risk to develop kidney stones and chronic kidney disease, but underlying mechanisms have not been addressed to date.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland. .,National Center for Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland.
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,National Center for Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Nati Hernando
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,National Center for Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
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15
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Fuente R, Gil-Peña H, Claramunt-Taberner D, Hernández-Frías O, Fernández-Iglesias Á, Hermida-Prado F, Anes-González G, Rubio-Aliaga I, Lopez JM, Santos F. Marked alterations in the structure, dynamics and maturation of growth plate likely explain growth retardation and bone deformities of young Hyp mice. Bone 2018; 116:187-195. [PMID: 30096468 DOI: 10.1016/j.bone.2018.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/02/2018] [Accepted: 08/07/2018] [Indexed: 12/11/2022]
Abstract
Mechanisms underlying growth impairment and bone deformities in X-linked hypophosphatemia are not fully understood. We here describe marked alterations in the structure, dynamics and maturation of growth plate in growth-retarded young Hyp mice, in comparison with wild type mice. Hyp mice exhibited reduced proliferation and apoptosis rates of chondrocytes as well as severe disturbance in the process of chondrocyte hypertrophy disclosed by abnormal expression of proteins likely involved in cell enlargement, irregular chondro-osseous junction and disordered bone trabecular pattern and vascular invasion in the primary spongiosa. (Hyp mice had elevated circulating FGF23 levels and over activation of ERK in the growth plate.) All these findings provide a basis to explain growth impairment and metaphyseal deformities in XLH. Hyp mice were compared with wild type mice serum parameters, nutritional status and growth impairment by evaluation of growth cartilage and bone structures. Hyp mice presented hyphosphatemia with high FGF23 levels. Weight gain and longitudinal growth resulted reduced in them with numerous skeletal abnormalities at cortical bone. It was also observed aberrant trabecular organization at primary spongiosa and atypical growth plate organization with abnormal proliferation and hypertrophy of chondrocytes and diminished apoptosis and vascular invasion processes. The present results show for the first time the abnormalities present in the growth plate of young Hyp mice and suggest that both cartilage and bone alterations may be involved in the growth impairment and the long bone deformities of XLH.
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Affiliation(s)
- Rocío Fuente
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain; Harvard School of Dental Medicine, Developmental Biology, Harvard University, Boston, MA, USA
| | - Helena Gil-Peña
- Department of Pediatrics, Hospital Universitario Central de Asturias (HUCA), Oviedo, Asturias, Spain.
| | - Débora Claramunt-Taberner
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Olaya Hernández-Frías
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Ángela Fernández-Iglesias
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Francisco Hermida-Prado
- Department of Otolaryngologist, Hospital Universitario Central de Asturias, Instituto Universitario de Oncología del Principado de Asturias, Oviedo, Spain
| | - Gonzalo Anes-González
- Department of Pediatrics, Hospital Universitario Central de Asturias (HUCA), Oviedo, Asturias, Spain
| | - Isabel Rubio-Aliaga
- University of Zurich, Institute of Physiology, Kidney and Acid-base Physiology Group, Zurich, Switzerland
| | - Jose Manuel Lopez
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Fernando Santos
- Division of Pediatrics, Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain; Department of Pediatrics, Hospital Universitario Central de Asturias (HUCA), Oviedo, Asturias, Spain
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16
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Lister A, Bourgeois S, Imenez Silva PH, Rubio-Aliaga I, Marbet P, Walsh J, Shelton LM, Keller B, Verrey F, Devuyst O, Giesbertz P, Daniel H, Goldring CE, Copple IM, Wagner CA, Odermatt A. NRF2 regulates the glutamine transporter Slc38a3 (SNAT3) in kidney in response to metabolic acidosis. Sci Rep 2018; 8:5629. [PMID: 29618784 PMCID: PMC5884861 DOI: 10.1038/s41598-018-24000-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 03/19/2018] [Indexed: 12/28/2022] Open
Abstract
Expression of the glutamine transporter SNAT3 increases in kidney during metabolic acidosis, suggesting a role during ammoniagenesis. Microarray analysis of Nrf2 knock-out (KO) mouse kidney identified Snat3 as the most significantly down-regulated transcript compared to wild-type (WT). We hypothesized that in the absence of NRF2 the kidney would be unable to induce SNAT3 under conditions of metabolic acidosis and therefore reduce the availability of glutamine for ammoniagenesis. Metabolic acidosis was induced for 7 days in WT and Nrf2 KO mice. Nrf2 KO mice failed to induce Snat3 mRNA and protein expression during metabolic acidosis. However, there were no differences in blood pH, bicarbonate, pCO2, chloride and calcium or urinary pH, ammonium and phosphate levels. Normal induction of ammoniagenic enzymes was observed whereas several amino acid transporters showed differential regulation. Moreover, Nrf2 KO mice during acidosis showed increased expression of renal markers of oxidative stress and injury and NRF2 activity was increased during metabolic acidosis in WT kidney. We conclude that NRF2 is required to adapt the levels of SNAT3 in response to metabolic acidosis. In the absence of NRF2 and SNAT3, the kidney does not have any major acid handling defect; however, increased oxidative stress and renal injury may occur.
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Affiliation(s)
- Adam Lister
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Pedro H Imenez Silva
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Philippe Marbet
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Joanne Walsh
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Luke M Shelton
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Bettina Keller
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Francois Verrey
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Olivier Devuyst
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Pieter Giesbertz
- Department of Biochemistry, ZIEL Research Center of Nutrition and Food Sciences, Technische Universität München, Freising, Germany
| | - Hannelore Daniel
- Department of Biochemistry, ZIEL Research Center of Nutrition and Food Sciences, Technische Universität München, Freising, Germany
| | - Christopher E Goldring
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Ian M Copple
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Carsten A Wagner
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland. .,National Center for Competence in Research Kidney.CH, Zürich, Switzerland.
| | - Alex Odermatt
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland. .,National Center for Competence in Research Kidney.CH, Zürich, Switzerland.
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17
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Affiliation(s)
- Isabel Rubio-Aliaga
- a Institute of Physiology, the National Center for Competence in Research NCCR Kidney, University of Zurich , Zurich , Switzerland
| | - Carsten A Wagner
- a Institute of Physiology, the National Center for Competence in Research NCCR Kidney, University of Zurich , Zurich , Switzerland
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18
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Elliott RM, de Roos B, Duthie SJ, Bouwman FG, Rubio-Aliaga I, Crosley LK, Mayer C, Polley AC, Heim C, Coort SL, Evelo CT, Mulholland F, Daniel H, Mariman EC, Johnson IT. Transcriptome analysis of peripheral blood mononuclear cells in human subjects following a 36 h fast provides evidence of effects on genes regulating inflammation, apoptosis and energy metabolism. Genes Nutr 2014; 9:432. [PMID: 25260660 DOI: 10.1007/s12263-014-0432-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/20/2014] [Indexed: 12/29/2022]
Abstract
There is growing interest in the potential health benefits of diets that involve regular periods of fasting. While animal studies have provided compelling evidence that feeding patterns such as alternate-day fasting can increase longevity and reduce incidence of many chronic diseases, the evidence from human studies is much more limited and equivocal. Additionally, although several candidate processes have been proposed to contribute to the health benefits observed in animals, the precise molecular mechanisms responsible remain to be elucidated. The study described here examined the effects of an extended fast on gene transcript profiles in peripheral blood mononuclear cells from ten apparently healthy subjects, comparing transcript profiles after an overnight fast, sampled on four occasions at weekly intervals, with those observed on a single occasion after a further 24 h of fasting. Analysis of the overnight fasted data revealed marked inter-individual differences, some of which were associated with parameters such as gender and subject body mass. For example, a striking positive association between body mass index and the expression of genes regulated by type 1 interferon was observed. Relatively subtle changes were observed following the extended fast. Nonetheless, the pattern of changes was consistent with stimulation of fatty acid oxidation, alterations in cell cycling and apoptosis and decreased expression of key pro-inflammatory genes. Stimulation of fatty acid oxidation is an expected response, most likely in all tissues, to fasting. The other processes highlighted provide indications of potential mechanisms that could contribute to the putative beneficial effects of intermittent fasting in humans.
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Affiliation(s)
- R M Elliott
- Institute of Food Research, Colney Lane, Norwich, UK,
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19
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20
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Sabrautzki S, Rubio-Aliaga I, Hans W, Fuchs H, Rathkolb B, Calzada-Wack J, Cohrs CM, Klaften M, Seedorf H, Eck S, Benet-Pagès A, Favor J, Esposito I, Strom TM, Wolf E, Lorenz-Depiereux B, Hrabĕ de Angelis M. Erratum to: New mouse models for metabolic bone diseases generated by genome-wide ENU mutagenesis. Mamm Genome 2014. [PMCID: PMC4714016 DOI: 10.1007/s00335-014-9534-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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21
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Castañeda-Gutiérrez E, Moser M, García-Ródenas C, Raymond F, Mansourian R, Rubio-Aliaga I, Viguet-Carrin S, Metairon S, Ammon-Zufferey C, Avanti-Nigro O, Macé K, Silva-Zolezzi I. Effect of a mixture of bovine milk oligosaccharides, Lactobacillus rhamnosus NCC4007 and long-chain polyunsaturated fatty acids on catch-up growth of intra-uterine growth-restricted rats. Acta Physiol (Oxf) 2014; 210:161-73. [PMID: 23834457 DOI: 10.1111/apha.12145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/15/2013] [Accepted: 07/02/2013] [Indexed: 12/21/2022]
Abstract
AIM To investigate the effect of a nutritional mixture (bovine milk oligosaccharides, Lactobacillus rhamnosus NCC4007, arachidonic and docosahexaenoic acid) on growth of intrauterine growth-restricted (IUGR) rats. METHODS IUGR was induced by maternal food restriction. The offspring (males and females) were assigned to: REF (non-IUGR, no mixture), IUGRc (IUGR, no mixture), or IUGRmx (IUGR, mixture). The mixture was given from day 7 to day 58, when tissues and plasma from half of the animals were collected for hormones, metabolites and microarray analysis. The rest received a high-fat diet (HFD) until day 100. Glucose tolerance was measured at 56 and 98 days, and body fat content at 21, 52 and 97 days. RESULTS IUGRmx had the greatest growth during lactation, but from day 22 to day 54, both IUGR groups gained less body weight than the REF (P < 0.05). In the short-term (58 days), IUGRmx tended to be longer (P = 0.06) and had less body fat (P = 0.03) than IUGRc. These differences were not seen after HFD. Microarray analysis of hepatic mRNA expression at 58 and 100 days revealed a gender-dependent treatment effect, and expression of genes related to lipid metabolism was the most affected. Twelve of these genes were selected for studying differences in DNA methylation in the promoter region, for some, we observed age- and gender-related differences but none because of treatment. CONCLUSION The nutritional intervention promoted catch-up growth and normalized excessive adiposity in IUGR animals at short-term. The benefits did not extend after a period of HFD. IUGR and early diet had gender-dependent effects on hepatic gene expression.
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Affiliation(s)
| | - M. Moser
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
| | - C. García-Ródenas
- Department of Nutrition and Health; Nestlé Research Center; Lausanne Switzerland
| | - F. Raymond
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
| | - R. Mansourian
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
| | - I. Rubio-Aliaga
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
| | - S. Viguet-Carrin
- Department of Nutrition and Health; Nestlé Research Center; Lausanne Switzerland
| | - S. Metairon
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
| | - C. Ammon-Zufferey
- Department of Nutrition and Health; Nestlé Research Center; Lausanne Switzerland
| | - O. Avanti-Nigro
- Department of Nutrition and Health; Nestlé Research Center; Lausanne Switzerland
| | - K. Macé
- Department of Nutrition and Health; Nestlé Research Center; Lausanne Switzerland
| | - I. Silva-Zolezzi
- Department of Bioanalytical Sciences; Nestlé Research Center; Lausanne Switzerland
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22
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Giacopo AD, Rubio-Aliaga I, Cantone A, Artunc F, Rexhepaj R, Frey-Wagner I, Font-Llitjós M, Gehring N, Stange G, Jaenecke I, Mohebbi N, Closs EI, Palacín M, Nunes V, Daniel H, Lang F, Capasso G, Wagner CA. Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+AT (Slc7a9) in mice. Am J Physiol Renal Physiol 2013; 305:F1645-55. [DOI: 10.1152/ajprenal.00221.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT) and SLC7A9 ( b 0,+ AT). Gene targeting of the catalytic subunit ( Slc7a9) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b0,+. No remarkable gene expression changes were observed in other amino acid transporters and the peptide transporters in the intestine and kidney. Furthermore, the glomerular filtration rate (GFR) was reduced by 30% in knockout animals compared with wild-type animals. The fractional excretion of arginine was increased as expected (∼100%), but fractional excretions of lysine (∼35%), ornithine (∼16%), and cystine (∼11%) were less affected. Loss of function of b0,+AT reduced transport of cystine and arginine in renal BBMVs and completely abolished the exchanger activity of dibasic amino acids with neutral amino acids. In conclusion, loss of Slc7a9 function decreases the GFR and increases the excretion of several amino acids to a lesser extent than expected with no clear regulation at the mRNA and protein level of alternative transporters and no increased renal epithelial uptake. These observations indicate that transporters located in distal segments of the kidney and/or metabolic pathways may partially compensate for Slc7a9 loss of function.
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Affiliation(s)
- Andrea Di Giacopo
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Alessandra Cantone
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Ferruh Artunc
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Rexhep Rexhepaj
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | | | - Mariona Font-Llitjós
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- U730 CIBERER, Barcelona, Spain
| | - Nicole Gehring
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Gerti Stange
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Jaenecke
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Nilufar Mohebbi
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Ellen I. Closs
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Manuel Palacín
- IRB Barcelona, Department of Biochemistry and Molecular Biology, University of Barcelona and U731 CIBERER, Barcelona, Spain
| | - Virginia Nunes
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- Department of Physiological Sciences II, University of Barcelona, Spain; and
- U730 CIBERER, Barcelona, Spain
| | - Hannelore Daniel
- Molecular Nutrition Unit, Technical University of Munich, Freising, Germany
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Giovambattista Capasso
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Carsten A. Wagner
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
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23
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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24
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Sailer M, Dahlhoff C, Giesbertz P, Eidens MK, de Wit N, Rubio-Aliaga I, Boekschoten MV, Müller M, Daniel H. Increased plasma citrulline in mice marks diet-induced obesity and may predict the development of the metabolic syndrome. PLoS One 2013; 8:e63950. [PMID: 23691124 PMCID: PMC3653803 DOI: 10.1371/journal.pone.0063950] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 04/10/2013] [Indexed: 12/31/2022] Open
Abstract
In humans, plasma amino acid concentrations of branched-chain amino acids (BCAA) and aromatic amino acids (AAA) increase in states of obesity, insulin resistance and diabetes. We here assessed whether these putative biomarkers can also be identified in two different obesity and diabetic mouse models. C57BL/6 mice with diet-induced obesity (DIO) mimic the metabolic impairments of obesity in humans characterized by hyperglycemia, hyperinsulinemia and hepatic triglyceride accumulation. Mice treated with streptozotocin (STZ) to induce insulin deficiency were used as a type 1 diabetes model. Plasma amino acid profiling of two high fat (HF) feeding trials revealed that citrulline and ornithine concentrations are elevated in obese mice, while systemic arginine bioavailability (ratio of plasma arginine to ornithine + citrulline) is reduced. In skeletal muscle, HF feeding induced a reduction of arginine levels while citrulline levels were elevated. However, arginine or citrulline remained unchanged in their key metabolic organs, intestine and kidney. Moreover, the intestinal conversion of labeled arginine to ornithine and citrulline in vitro remained unaffected by HF feeding excluding the intestine as prime site of these alterations. In liver, citrulline is mainly derived from ornithine in the urea cycle and DIO mice displayed reduced hepatic ornithine levels. Since both amino acids share an antiport mechanism for mitochondrial import and export, elevated plasma citrulline may indicate impaired hepatic amino acid handling in DIO mice. In the insulin deficient mice, plasma citrulline and ornithine levels also increased and additionally these animals displayed elevated BCAA and AAA levels like insulin resistant and diabetic patients. Therefore, type 1 diabetic mice but not DIO mice show the “diabetic fingerprint” of plasma amino acid changes observed in humans. Additionally, citrulline may serve as an early indicator of the obesity-dependent metabolic impairments.
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Affiliation(s)
- Manuela Sailer
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Christoph Dahlhoff
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
- PhD Graduate School ‘Epigenetics, Imprinting and Nutrition’, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Pieter Giesbertz
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Mena K. Eidens
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Nicole de Wit
- Netherlands Nutrigenomics Centre, TI Food & Nutrition, Wageningen University, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Isabel Rubio-Aliaga
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Mark V. Boekschoten
- Netherlands Nutrigenomics Centre, TI Food & Nutrition, Wageningen University, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Michael Müller
- Netherlands Nutrigenomics Centre, TI Food & Nutrition, Wageningen University, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Hannelore Daniel
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
- * E-mail:
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25
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Abstract
The complexity of food organism interactions necessitates the use of model organisms to understand physiological and pathological processes. In nutrition research, model organisms were initially used to understand how macro and micronutrients are handled in the organism. Currently, in nutritional systems biology, models of increasing complexity are needed in order to determine the global organisation of a biological system and the interaction with food and food components. Originally driven by genetics, certain model organisms have become most prominent. Model organisms are more accessible systems than human beings and include bacteria, yeast, flies, worms, and mammals such as mice. Here, the origin and the reasons to become the most prominent models are presented. Moreover, their applicability in molecular nutrition research is illustrated with selected examples.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Molecular Nutrition Unit, Department of Food and Nutrition, Technische Universität München, Freising, Germany.
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26
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Birk RZ, Rubio-Aliaga I, Boekschoten MV, Müller M, Daniel H. Differential regulation of pancreas digestive enzymes during the development of diet‐induced‐obesity of C57BL/6J mice. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.375.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ruth Z Birk
- Department of NutritionAriel University CenterArielIsrael
| | - Isabel Rubio-Aliaga
- Molecular Nutrition UnitResearch Center for Nutrition and Food SciencesTechnische Universitat MunchenFreising-WeihenstephanGermany
| | - Mark V Boekschoten
- Netherlands Nutrigenomics CentreTop Institute Food and NutritionMetabolism and Genomics GroupWageningen UniversityWageningenNetherlands
| | - Michael Müller
- Netherlands Nutrigenomics CentreTop Institute Food and NutritionMetabolism and Genomics GroupWageningen UniversityWageningenNetherlands
| | - Hannelore Daniel
- Molecular Nutrition UnitResearch Center for Nutrition and Food SciencesTechnische Universitat MunchenFreising-WeihenstephanGermany
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27
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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28
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Rubio-Aliaga I, Marvin-Guy LF, Wang P, Wagniere S, Mansourian R, Fuerholz A, Saris WHM, Astrup A, Mariman ECM, Kussmann M. Mechanisms of weight maintenance under high- and low-protein, low-glycaemic index diets. Mol Nutr Food Res 2011; 55:1603-12. [PMID: 21957032 DOI: 10.1002/mnfr.201100081] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 07/06/2011] [Accepted: 07/09/2011] [Indexed: 01/19/2023]
Abstract
SCOPE Weight maintenance after intended weight loss is a challenge in an obesogenic environment. In a large multicentre dietary intervention study (DiOGenes), it has recently been demonstrated that a high-protein/low-glycaemic index (HP/LGI) diet was slightly more efficient in maintaining weight loss than low-protein/LGI or high-GI (LP/LGI or HGI) diets. Here, we use a proteomic approach to assess the molecular mechanisms behind this positive effect. METHODS AND RESULTS A subset of the most successful (weight loser, n=12) and unsuccessful (weight re-gainer, n=12) individuals consuming the LGI diets with either high- or low-protein content (HP or LP/LGI), following an initial calorie deficit run-in weight loss phase, were analyzed at the plasma protein level. Proteomic analysis revealed 18 proteins regulated after 6 months of the dietary weight maintenance phase. Furthermore, 12 proteins were significantly regulated as a function of success rate under an HP diet, arising as candidate biomarkers of mechanisms of successful weight maintenance under an HP/LGI diet. Pregnancy-zone protein (PZP) and protein S (PROS1) were revealed as novel biomarkers of weight maintenance showing opposite effects. CONCLUSION Semantic network analysis of the 12 regulated proteins revealed that under an HP/LGI an anti-atherogenic effect and alterations of fat metabolism were associated with the success of maintaining the initial weight loss.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Functional Genomics Group, Department of Bioanalytical Sciences, Nestlé Research Center, Lausanne, Switzerland.
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29
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Groebner AE, Zakhartchenko V, Bauersachs S, Rubio-Aliaga I, Daniel H, Büttner M, Reichenbach HD, Meyer HHD, Wolf E, Ulbrich SE. Reduced amino acids in the bovine uterine lumen of cloned versus in vitro fertilized pregnancies prior to implantation. Cell Reprogram 2011; 13:403-10. [PMID: 21774685 DOI: 10.1089/cell.2011.0006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fetal overgrowth and placental abnormalities frequently occur in pregnancies following somatic cell nuclear transfer (SCNT). An optimal intrauterine supply of amino acids (AA) is of specific importance for the development of the bovine preimplantation embryo, and a defective regulation of AA supply might contribute to pregnancy failures. Thus, we analyzed 41 AA and derivatives by liquid chromatography-tandem mass spectrometry in uterine flushings of day 18 pregnant heifers carrying in vitro fertilized (IVF) or SCNT embryos, which were cultured under identical conditions until transfer to recipients. The concentrations of several AA were reduced in samples from SCNT pregnancies: L-leucine (1.8-fold), L-valine (1.6-fold), L-isoleucine (1.9-fold), L-phenylalanine (1.5-fold), L-glutamic acid (3.9-fold), L-aspartic acid (4.0-fold), L-proline (2.6-fold), L-alanine (2.0-fold), L-arginine (2.5-fold), and L-lysine (1.9-fold). The endometrial transcript abundance for the AA transporter solute carrier family 7 (amino acid transporter, L-type), member 8 (SLC7A8) was also 2.4-fold lower in SCNT pregnancies. O-phosphoethanolamine (PetN) was 11-fold (p=0.0001) reduced in the uterine fluid of animals carrying an SCNT conceptus, pointing toward changes of the phospholipid metabolism. We provide evidence for disturbed embryo-maternal interactions in the preimplantation period after transfer of SCNT embryos, which may contribute to developmental abnormalities. These are unlikely related to the major embryonic pregnancy recognition signal interferon-tau, because similar activities were detected in uterine flushings of the SCNT and IVF groups.
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Affiliation(s)
- Anna E Groebner
- Physiology Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
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30
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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31
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de Wit NJW, Boekschoten MV, Bachmair EM, Hooiveld GJEJ, de Groot PJ, Rubio-Aliaga I, Daniel H, Müller M. Dose-dependent effects of dietary fat on development of obesity in relation to intestinal differential gene expression in C57BL/6J mice. PLoS One 2011; 6:e19145. [PMID: 21547079 PMCID: PMC3081848 DOI: 10.1371/journal.pone.0019145] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 03/18/2011] [Indexed: 11/19/2022] Open
Abstract
Excessive intake of dietary fat is known to be a contributing factor in the development of obesity. In this study, we determined the dose-dependent effects of dietary fat on the development of this metabolic condition with a focus on changes in gene expression in the small intestine. C57BL/6J mice were fed diets with either 10, 20, 30 or 45 energy% (E%) derived from fat for four weeks (n = 10 mice/diet). We found a significant higher weight gain in mice fed the 30E% and 45E% fat diet compared to mice on the control diet. These data indicate that the main shift towards an obese phenotype lies between a 20E% and 30E% dietary fat intake. Analysis of differential gene expression in the small intestine showed a fat-dose dependent gradient in differentially expressed genes, with the highest numbers in mice fed the 45E% fat diet. The main shift in fat-induced differential gene expression was found between the 30E% and 45E% fat diet. Furthermore, approximately 70% of the differentially expressed genes were changed in a fat-dose dependent manner. Many of these genes were involved in lipid metabolism-related processes and were already differentially expressed on a 30E% fat diet. Taken together, we conclude that up to 20E% of dietary fat, the small intestine has an effective ‘buffer capacity’ for fat handling. From 30E% of dietary fat, a switch towards an obese phenotype is triggered. We further speculate that especially fat-dose dependently changed lipid metabolism-related genes are involved in development of obesity.
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Affiliation(s)
- Nicole J. W. de Wit
- Netherlands Nutrigenomics Centre, Top Institute Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Mark V. Boekschoten
- Netherlands Nutrigenomics Centre, Top Institute Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
- * E-mail:
| | - Eva-Maria Bachmair
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Guido J. E. J. Hooiveld
- Netherlands Nutrigenomics Centre, Top Institute Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Philip J. de Groot
- Netherlands Nutrigenomics Centre, Top Institute Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Isabel Rubio-Aliaga
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Hannelore Daniel
- Molecular Nutrition Unit, Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Michael Müller
- Netherlands Nutrigenomics Centre, Top Institute Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
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32
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Rubio-Aliaga I, Roos BD, Sailer M, McLoughlin GA, Boekschoten MV, van Erk M, Bachmair EM, van Schothorst EM, Keijer J, Coort SL, Evelo C, Gibney MJ, Daniel H, Muller M, Kleemann R, Brennan L. Alterations in hepatic one-carbon metabolism and related pathways following a high-fat dietary intervention. Physiol Genomics 2011; 43:408-16. [DOI: 10.1152/physiolgenomics.00179.2010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Obesity frequently leads to insulin resistance and the development of hepatic steatosis. To characterize the molecular changes that promote hepatic steatosis, transcriptomics, proteomics, and metabolomics technologies were applied to liver samples from C57BL/6J mice obtained from two independent intervention trials. After 12 wk of high-fat feeding the animals became obese, hyperglycemic, and insulin resistant, had elevated levels of blood cholesterol and VLDL, and developed hepatic steatosis. Nutrigenomic analysis revealed alterations of key metabolites and enzyme transcript levels of hepatic one-carbon metabolism and related pathways. The hepatic oxidative capacity and the lipid milieu were significantly altered, which may play a key role in the development of insulin resistance. Additionally, high choline levels were observed after the high-fat diet. Previous studies have linked choline levels with insulin resistance and hepatic steatosis in conjunction with changes of certain metabolites and enzyme levels of one-carbon metabolism. The present results suggest that the coupling of high levels of choline and low levels of methionine plays an important role in the development of insulin resistance and liver steatosis. In conclusion, the complexities of the alterations induced by high-fat feeding are multifactorial, indicating that the interplay between several metabolic pathways is responsible for the pathological consequences.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Molecular Nutrition Unit, ZIEL-Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Baukje de Roos
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Manuela Sailer
- Molecular Nutrition Unit, ZIEL-Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Gerard A. McLoughlin
- UCD Institute of Food and Health, University College Dublin, Dublin, Ireland; and
| | - Mark V. Boekschoten
- Netherlands Nutrigenomics Centre, TI Food and Nutrition and
- Division of Human Nutrition, Wageningen University, Wageningen
| | - Marjan van Erk
- Physiological Genomics team, BU Biosciences, TNO-Quality of Life, Zeist
| | - Eva-Maria Bachmair
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | | | - Jaap Keijer
- Human and Animal Physiology, Wageningen University, Wageningen
| | - Susan L. Coort
- Department of Bioinformatics, BiGCaT, Maastricht University, Maastricht; and
| | - Chris Evelo
- Department of Bioinformatics, BiGCaT, Maastricht University, Maastricht; and
| | - Michael J. Gibney
- UCD Institute of Food and Health, University College Dublin, Dublin, Ireland; and
| | - Hannelore Daniel
- Molecular Nutrition Unit, ZIEL-Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Michael Muller
- Netherlands Nutrigenomics Centre, TI Food and Nutrition and
| | - Robert Kleemann
- Department of Vascular and Metabolic Diseases, TNO-Quality of Life, Leiden, The Netherlands
| | - Lorraine Brennan
- UCD Institute of Food and Health, University College Dublin, Dublin, Ireland; and
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Bouwman FG, de Roos B, Rubio-Aliaga I, Crosley LK, Duthie SJ, Mayer C, Horgan G, Polley AC, Heim C, Coort SLM, Evelo CT, Mulholland F, Johnson IT, Elliott RM, Daniel H, Mariman ECM. 2D-electrophoresis and multiplex immunoassay proteomic analysis of different body fluids and cellular components reveal known and novel markers for extended fasting. BMC Med Genomics 2011; 4:24. [PMID: 21439033 PMCID: PMC3073865 DOI: 10.1186/1755-8794-4-24] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 03/25/2011] [Indexed: 11/20/2022] Open
Abstract
Background Proteomic technologies applied for profiling human biofluids and blood cells are considered to reveal new biomarkers of exposure or provide insights into novel mechanisms of adaptation. Methods Both a non-targeted (classical 2D-electrophoresis combined with mass spectrometry) as well as a targeted proteomic approach (multiplex immunoassay) were applied to investigate how fasting for 36 h, as compared to 12 h, affects the proteome of platelets, peripheral blood mononuclear cells (PBMC), plasma, urine and saliva collected from ten healthy volunteers. Results Between-subject variability was highest in the plasma proteome and lowest in the PBMC proteome. Random Forests analysis performed on the entire dataset revealed that changes in the level of the RhoGDI2 protein in PBMC and plasma ApoA4 levels were the two most obvious biomarkers of an extended fasting. Random Forests (RF) analysis of the multiplex immunoassay data revealed leptin and MMP-3 as biomarkers for extended fasting. However, high between-subject variability may have masked the extended fasting effects in the proteome of the biofluids and blood cells. Conclusions Identification of significantly changed proteins in biofluids and blood cells using a non-targeted approach, together with the outcome of targeted analysis revealed both known and novel markers for a 36 h fasting period, including the cellular proteins RhoGDI2 and CLIC1, and plasma proteins ApoA4, leptin and MMP-3. The PBMC proteome exhibited the lowest between-subject variability and therefore these cells appear to represent the best biosamples for biomarker discovery in human nutrigenomics.
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Affiliation(s)
- Freek G Bouwman
- Department of Human Biology, NUTRIM, Maastricht University, Maastricht, The Netherlands
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Groebner AE, Rubio-Aliaga I, Schulke K, Reichenbach HD, Daniel H, Wolf E, Meyer HHD, Ulbrich SE. Increase of essential amino acids in the bovine uterine lumen during preimplantation development. Reproduction 2011; 141:685-95. [PMID: 21383026 DOI: 10.1530/rep-10-0533] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Amino acids (AAs) are crucial for the developing conceptus prior to implantation. To provide insights into the requirements of the bovine embryo, we determined the AA composition of the uterine fluid. At days 12, 15, and 18 post-estrus, the uteri of synchronized pregnant and non-pregnant Simmental heifers were flushed for the analysis of 41 AAs and their derivatives by liquid chromatography-tandem mass spectrometry. The ipsilateral endometrium was sampled for quantitative PCR. In addition to a pregnancy-dependent increase of the essential AAs (P<0.01), we detected elevated concentrations for most non-essential proteinogenic AAs. Histidine (His) and the expression of the His/peptide transporter solute carrier 15A3 (SLC15A3) were significantly increased at day 18 of pregnancy in vivo. In addition, SLC15A3 was predominantly stimulated by trophoblast-derived interferon-τ in stroma cells of an in vitro co-culture model of endometrial cells. Our results show an increased concentration of AAs most likely to optimally provide the elongating pre-attachment conceptus with nutrients.
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Affiliation(s)
- Anna E Groebner
- Physiology Weihenstephan, Z I E L Research Center for Nutrition and Food Sciences, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising, Germany
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Wittwer J, Rubio-Aliaga I, Hoeft B, Bendik I, Weber P, Daniel H. Nutrigenomics in human intervention studies: Current status, lessons learned and future perspectives. Mol Nutr Food Res 2011; 55:341-58. [DOI: 10.1002/mnfr.201000512] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 11/08/2022]
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Spanier B, Rubio-Aliaga I, Hu H, Daniel H. Altered signalling from germline to intestine pushes daf-2;pept-1 Caenorhabditis elegans into extreme longevity. Aging Cell 2010; 9:636-46. [PMID: 20550516 DOI: 10.1111/j.1474-9726.2010.00591.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The insulin-like signalling pathway is a central regulator of development, metabolism, stress resistance and lifespan in eukaryotes. Caenorhabditis elegans daf-2(e1370) animals with a loss-of-function mutation in the insulin-like receptor live twice as long as wild-type animals, and the additional knockout of the intestinal di- and tripeptide transporter pept-1 further increases lifespan by 60%. In assessing the underlying molecular mechanisms for this phenomenon, microarray-based transcriptome data sets of daf-2(e1370) and daf-2(e1370);pept-1(lg601) animals were compared with a focus on genes that showed significantly higher changes in expression levels in daf-2;pept-1 than in daf-2. We identified 187 genes with at least fourfold decreased transcript levels and 170 with more than a fourfold increase. A large fraction of the down-regulated genes encode proteins involved in germline proliferation and reproduction. The DAF-9/DAF-12 signalling cascade was identified as a prime pathway that mediates the longevity of daf-2;pept-1 with a strict dependance on DAF-16. Loss of DAF-9/DAF-12 or KRI-1 reduces the lifespan of daf-2;pept-1 to that of the daf-2 mutant. Amongst the DAF-16 target genes, numerous enzymes involved in the defence of reactive oxygen species were with increased expression level in daf-2;pept-1. On a functional level, it was demonstrated that amongst those, a high de novo synthesis rate of glutathione is most important for the longevity phenotype of this strain. Taken together, a close interdependence of endocrine hormone signalling from germline to intestine was identified as an essential element in the control of the extreme longevity of C. elegans lacking a proper function of the insulin receptor and lacking the intestinal peptide transporter.
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Affiliation(s)
- Britta Spanier
- ZIEL Research Center of Nutrition and Food Sciences, Technische Universität München, Freising, Germany.
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Chen M, Singh A, Xiao F, Dringenberg U, Wang J, Engelhardt R, Yeruva S, Rubio-Aliaga I, Nässl AM, Kottra G, Daniel H, Seidler U. Gene ablation for PEPT1 in mice abolishes the effects of dipeptides on small intestinal fluid absorption, short-circuit current, and intracellular pH. Am J Physiol Gastrointest Liver Physiol 2010; 299:G265-74. [PMID: 20430876 DOI: 10.1152/ajpgi.00055.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PEPT1 function in mouse intestine has not been assessed by means of electrophysiology and methods to assess its role in intracellular pH and fluid homeostasis. Therefore, the effects of the dipeptide glycilsarcosin (Gly-Sar) on jejunal fluid absorption and villous enterocyte intracellular pH (pH(i)) in vivo, as well as on enterocyte[(14)C]Gly-Sar uptake, short-circuit current (I(sc)) response, and enterocyte pH(i) in vitro were determined in wild-type and PEPT1-deficient mice and in mice lacking PEPT1. Immunohistochemistry for PEPT1 failed to detect any protein in enterocyte apical membranes in Slc15a1(-/-) animals. Saturable Gly-Sar uptake in Slc15a1(-/-) everted sac preparations was no longer detectable. Similarly, Gly-Sar-induced jejunal I(sc) response in vitro was abolished. The dipeptide-induced increase in fluid absorption in vivo was also abolished in animals lacking PEPT1. Since PEPT1 acts as an acid loader in enterocytes, enterocyte pH(i) was measured in vivo by two-photon microscopy in SNARF-4-loaded villous enterocytes of exteriorized jejuni in anesthetized mice, as well as in BCECF-loaded enterocytes of microdissected jejunal villi. Gly-Sar-induced pH(i) decrease was no longer observed in the absence of PEPT1. A reversal of the proton gradient across the luminal membrane did not significantly diminish Gly-Sar-induced I(sc) response, whereas a depolarization of the apical membrane potential by high K(+) or via Na(+)-K(+)-ATPase inhibition strongly diminished Gly-Sar-induced I(sc) responses. This study demonstrates for the first time that proton-coupled electrogenic dipeptide uptake in the native small intestine, mediated by PEPT1, relies on the negative apical membrane potential as the major driving force and contributes significantly to intestinal fluid transport.
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Affiliation(s)
- Mingmin Chen
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany
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Rexhepaj R, Rotte A, Kempe DS, Sopjani M, Föller M, Gehring EM, Bhandaru M, Gruner I, Mack AF, Rubio-Aliaga I, Nässl AM, Daniel H, Kuhl D, Lang F. Stimulation of electrogenic intestinal dipeptide transport by the glucocorticoid dexamethasone. Pflugers Arch 2009; 459:191-202. [PMID: 19672619 DOI: 10.1007/s00424-009-0701-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 06/03/2009] [Accepted: 07/11/2009] [Indexed: 01/09/2023]
Abstract
According to recent in vitro experiments, the peptide transporter PepT2 is stimulated by the serum- and glucocorticoid-inducible kinase SGK1. The present study explored the contribution of SGK1 to the regulation of electrogenic intestinal peptide transport. Intestinal PepT1 was expressed in Xenopus oocytes, and peptide transport was determined by dual electrode voltage clamping. Peptide transport in intestinal segments was determined utilizing Ussing chamber. Cytosolic pH (pH( i )) was determined by BCECF fluorescence and Na(+)/H(+) exchanger activity was estimated from Na(+)-dependent pH recovery (pH ( i )) following an ammonium pulse. In PepT1-expressing Xenopus oocytes, coexpression of SGK1 enhanced electrogenic peptide transport. Intestinal transport and pH( i ) of untreated mice were similar in SGK1 knockout mice (sgk1 ( -/- )) and their wild-type littermates (sgk1 ( +/+ )). Glucocorticoid treatment (4 days 10 microg/g body weight (bw)/day dexamethasone) increased peptide transport in sgk1 ( +/+ ) but not in sgk1 (-/-) mice. Irrespective of dexamethasone treatment, luminal peptide (5 mM glycyl-glycine) led to a similar early decrease of pH( i ) in sgk1 (-/-) and sgk1 (+/+) mice, but to a more profound and sustained decline of pH( i ) in sgk1 (-/-) than in sgk1 ( +/+ ) mice. In the presence and absence of glycyl-glycine, pH ( i ) was significantly enhanced by dexamethasone treatment in sgk1 ( +/+ ) mice, an effect significantly blunted in sgk1 ( -/- ) mice. During sustained exposure to glycyl-glycine, pH ( i ) was significantly larger in sgk1 (+/+) mice than in sgk1 (-/-) mice, irrespective of dexamethasone treatment. In conclusion, basal intestinal peptide transport does not require stimulation by SGK1. Glucocorticoid treatment stimulates both Na(+)/H(+) exchanger activity and peptide transport, effects partially dependent on SGK1. Moreover, chronic exposure to glycyl-glycine stimulates Na(+)/H(+) exchanger activity, an effect again involving SGK1.
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Affiliation(s)
- Rexhep Rexhepaj
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
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Abstract
Aim of this review is to demonstrate the relevance of animal models created by ENU mutagenesis for the pharmaceutical community to understand diseases and the modulation of disease status by pharmaceutical compounds. We give an overview of what ENU mutagenesis in mice implies and introduce the main research centers running ENU mutagenesis projects. The different strategies of ENU mutagenesis screens are explained as well as the latest advances in mapping and mutation detection strategies, which until recently have been the main limiting step in forward genetics/phenotype-driven approaches. ENU mutagenesis in mice has shown its power by providing animal models for human monogenic diseases. Moreover, the development of modifier and sensitized screens extended this resource to models for multigenic diseases and thereby opened the perspective to understand the modulation of disease states. Finally, we provide information about the accessibility and availability of these models for academic research.
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Affiliation(s)
- Dian Soewarto
- Charité-University Medicine Berlin, Molecular Cancer Research Center, Augustenburger Platz 1, 13393 Berlin, Germany.
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Abe K, Klaften M, Narita A, Kimura T, Imai K, Kimura M, Rubio-Aliaga I, Wagner S, Jakob T, Hrabé de Angelis M. Genome-wide search for genes that modulate inflammatory arthritis caused by Ali18 mutation in mice. Mamm Genome 2009; 20:152-61. [PMID: 19238339 DOI: 10.1007/s00335-009-9170-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Accepted: 12/30/2008] [Indexed: 01/17/2023]
Abstract
Many of inflammatory diseases, including inflammatory arthritis, are multifactorial bases. The Ali18 semidominant mutation induced by N-ethyl-N-nitrosourea in the C3HeB/FeJ (C3H) genome causes spontaneous inflammation of peripheral limbs and elevated immunoglobulin E (IgE) levels in mice. Although the Ali18 locus was mapped to a single locus on chromosome 4, the arthritic phenotype of Ali18/+ mice was completely suppressed in F1 hybrid genetic backgrounds. To determine the chromosomal locations of the modifier loci affecting the severity of arthritis, an autosomal genome scan of 22 affected Ali18/+ F2 mice was conducted using C57BL/6J as a partner strain. Interestingly, regions on chromosomes 1 and 3 in C3H showed significant genetic interactions. Moreover, 174 N2 (backcross to Ali18/Ali18) and 267 F2 animals were used for measurement of arthritis scores and plasma IgE levels, and also for genotyping with 153 genome-wide single nucleotide polymorphism (SNP) markers. In N2 populations, two significant trait loci for arthritis scores on chromosomes 1 and 15 were detected. Although no significant scores were detected in F2 mice besides chromosome 4, a suggestive score was detected on chromosome 3. In addition, a two-dimensional genome scan using F2 identified five suggestive scores of chromosomal combinations, chromosomes 1 x 10, 2 x 6, 3 x 4, 4 x 9, and 6 x 15. No significant trait loci affecting IgE levels were detected in both N2 and F2 populations. Identification of the Ali18 modifier genes by further detailed analyses such as congenic strains and expression profiling may dissect molecular complexity in inflammatory diseases.
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Affiliation(s)
- Koichiro Abe
- Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Shimokasuya 143, Isehara, Kanagawa, 259-1193, Japan.
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Abstract
1. The peptide transporters belong to the peptide transporter (PTR) family and serve as integral membrane proteins for the cellular uptake of di- and tripeptides in the organism. By their ability also to transport peptidomimetics and other substrates with therapeutic activities or precursors of pharmacologically active agents, they are of considerable importance in pharmacology. 2. PEPT1 is the low-affinity, high-capacity transporter and is mainly expressed in the small intestine, whereas PEPT2 is the high-affinity, low-capacity transporter and has a broader distribution in the organism. 3. Targeted mouse models have revealed PEPT2 to be the dominant transporter for the reabsorption of di- and tripeptides and its pharmacological substrates in the organism, and for the removal of these substrates from the cerebrospinal fluid. Moreover, the peptide transporters undergo physiological and pharmacological regulation and, of great interest, are present in disease states where PEPT1 exhibits ectopic expression in colonic inflammation. 4. The paper reviews the structural characteristics of the peptide transporters, the structural requirements for substrates, the distribution of the peptide transporters in the organism, and finally their regulation in the organism in healthy and pathological situations.
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Affiliation(s)
- I Rubio-Aliaga
- Molecular Nutrition Unit, Technical University of Munich, Freising-Weihenstephan, Germany
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Tiedemann HB, Schneltzer E, Zeiser S, Rubio-Aliaga I, Wurst W, Beckers J, Przemeck GKH, Hrabé de Angelis M. Cell-based simulation of dynamic expression patterns in the presomitic mesoderm. J Theor Biol 2007; 248:120-9. [PMID: 17575987 DOI: 10.1016/j.jtbi.2007.05.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 04/04/2007] [Accepted: 05/14/2007] [Indexed: 11/25/2022]
Abstract
To model dynamic expression patterns in somitogenesis we developed a Java-application for simulating gene regulatory networks in many cells in parallel and visualising the results using the Java3D API, thus simulating the collective behaviour of many thousand cells. According to the 'clock-and-wave-front' model mesodermal segmentation of vertebrate embryos is regulated by a 'segmentation clock', which oscillates with a period of about 2h in mice, and a 'wave front' moving back with the growing caudal end of the presomitic mesoderm. The clock is realised through cycling expression of genes such as Hes1 and Hes7, whose gene products repress the transcription of their encoding genes in a negative feedback loop. By coupling the decay of the Hes1 mRNA to a gradient with the same features and mechanism of formation as the mesodermal Fgf8 gradient we can simulate typical features of the dynamic expression pattern of Hes1 in the presomitic mesoderm. Furthermore, our program is able to synchronise Hes1 oscillations in thousands of cells through simulated Delta-Notch signalling interactions.
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Affiliation(s)
- Hendrik B Tiedemann
- Institute of Experimental Genetics, GSF-National Research Centre for Environment and Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
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Frey IM, Rubio-Aliaga I, Siewert A, Sailer D, Drobyshev A, Beckers J, de Angelis MH, Aubert J, Bar Hen A, Fiehn O, Eichinger HM, Daniel H. Profiling at mRNA, protein, and metabolite levels reveals alterations in renal amino acid handling and glutathione metabolism in kidney tissue ofPept2−/−mice. Physiol Genomics 2007; 28:301-10. [PMID: 17077276 DOI: 10.1152/physiolgenomics.00193.2006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PEPT2 is an integral membrane protein in the apical membrane of renal epithelial cells that operates as a rheogenic transporter for di- and tripeptides and structurally related drugs. Its prime role is thought to be the reabsorption of filtered di- and tripeptides contributing to amino acid homeostasis. To elucidate the role of PEPT2 in renal amino acid metabolism we submitted kidney tissues of wild-type and a Pept2−/−mouse line to a comprehensive transcriptome, proteome and metabolome profiling and analyzed urinary amino acids and dipeptides. cDNA microarray analysis identified 147 differentially expressed transcripts in transporter-deficient animals, and proteome analysis by 2D-PAGE and MALDI-TOF-MS identified 37 differentially expressed proteins. Metabolite profiling by GC-MS revealed predominantly altered concentrations of amino acids and derivatives. Urinary excretion of amino acids demonstrated increased glycine and cysteine/cystine concentrations and dipeptides in urine were assessed by amino acid analysis of urine samples before and after in vitro dipeptidase digestion. Dipeptides constituted a noticeable fraction of urinary amino acids in Pept2−/−animals, only, and dipeptide-bound glycine and cystine were selectively increased in Pept2−/−urine samples. These findings were confirmed by a drastically increased excretion of cysteinyl-glycine (cys-gly). Urinary loss of cys-gly together with lower concentrations of cysteine, glycine, and oxoproline in kidney tissue and altered expression of mRNA and proteins involved in glutathione (GSH) metabolism suggests that PEPT2 is predominantly a system for reabsorption of cys-gly originating from GSH break-down, thus contributing to resynthesis of GSH.
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Affiliation(s)
- Isabelle M Frey
- Molecular Nutrition Unit, Technical University of Munich, Freising, Germany
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Rubio-Aliaga I, Soewarto D, Wagner S, Klaften M, Fuchs H, Kalaydjiev S, Busch DH, Klempt M, Rathkolb B, Wolf E, Abe K, Zeiser S, Przemeck GKH, Beckers J, de Angelis MH. A genetic screen for modifiers of the delta1-dependent notch signaling function in the mouse. Genetics 2006; 175:1451-63. [PMID: 17179084 PMCID: PMC1840053 DOI: 10.1534/genetics.106.067298] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Notch signaling pathway is an evolutionarily conserved transduction pathway involved in embryonic patterning and regulation of cell fates during development. Recent studies have demonstrated that this pathway is integral to a complex system of interactions, which are also involved in distinct human diseases. Delta1 is one of the known ligands of the Notch receptors. Mice homozygous for a loss-of-function allele of the Delta1 gene Dll1(lacZ/lacZ) die during embryonic development. Here, we present the results of two phenotype-driven modifier screens. Heterozygous Dll1(lacZ) knockout animals were crossed with ENU-mutagenized mice and screened for dysmorphological, clinical chemical, and immunological variants that are dependent on the Delta1 loss-of-function allele. First, we show that mutagenized heterozygous Dll1(lacZ) offspring have reduced body weight and altered specific clinical chemical parameters, including changes in metabolites and electrolytes relevant for kidney function. In our mutagenesis screen we have successfully generated 35 new mutant lines. Of major interest are 7 mutant lines that exhibit a Dll1(lacZ/+)-dependent phenotype. These mutant mouse lines provide excellent in vivo tools for studying the role of Notch signaling in kidney and liver function, cholesterol and iron metabolism, cell-fate decisions, and during maturation of T cells in the immune system.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Institute of Experimental Genetics, GSF Research Center for Environment and Health, 85764 Neuherberg, Germany
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Frey IM, Rubio-Aliaga I, Klempt M, Wolf E, Daniel H. Phenotype analysis of mice deficient in the peptide transporter PEPT2 in response to alterations in dietary protein intake. Pflugers Arch 2006; 452:300-6. [PMID: 16586099 DOI: 10.1007/s00424-005-0042-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 12/23/2005] [Indexed: 11/24/2022]
Abstract
The peptide transporter PEPT2 mediates cellular uptake of di- and tripeptides driven by an inwardly directed electrochemical proton gradient. In mammals PEPT2 is found in a variety of organs such as kidney, lung, brain, enteric nervous system, and mammary gland. Highest expression levels are observed in renal proximal tubules where PEPT2 contributes to reabsorption of filtered di- and tripeptides. To assess the physiological importance of the transporter in overall metabolism, we have generated a Pept2-/- mouse line that lacks a functional PEPT2 protein. Here we present data on body weight, organ weights, and blood pressure. Mice were then fed diets containing either 10, 20, or 30% (w/w) protein, and food and water intake rates as well as plasma and urine parameters were determined. In spite of PEPT2 expression in a variety of tissues, only subtle phenotypic changes were observed. Male PEPT2 null mice displayed lower bodyweight and lower relative heart weight, whereas, relative kidney weight was lower in female Pept2-/- mice. No differences were found in blood pressure. When fed diets with different protein contents, Pept2-/- mice adapted food intake to dietary protein content with higher consumption rates on low protein and reduced food intake rates on the high protein diet.
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Affiliation(s)
- Isabelle M Frey
- Molecular Nutrition Unit, Institute of Nutritional Sciences, Technical University of Munich, Am Forum 5, 85350, Freising-Weihenstephan, Germany
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Zeiser S, Liebscher HV, Tiedemann H, Rubio-Aliaga I, Przemeck GKH, de Angelis MH, Winkler G. Number of active transcription factor binding sites is essential for the Hes7 oscillator. Theor Biol Med Model 2006; 3:11. [PMID: 16504083 PMCID: PMC1402261 DOI: 10.1186/1742-4682-3-11] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Accepted: 02/23/2006] [Indexed: 11/25/2022] Open
Abstract
Background It is commonly accepted that embryonic segmentation of vertebrates is regulated by a segmentation clock, which is induced by the cycling genes Hes1 and Hes7. Their products form dimers that bind to the regulatory regions and thereby repress the transcription of their own encoding genes. An increase of the half-life of Hes7 protein causes irregular somite formation. This was shown in recent experiments by Hirata et al. In the same work, numerical simulations from a delay differential equations model, originally invented by Lewis, gave additional support. For a longer half-life of the Hes7 protein, these simulations exhibited strongly damped oscillations with, after few periods, severely attenuated the amplitudes. In these simulations, the Hill coefficient, a crucial model parameter, was set to 2 indicating that Hes7 has only one binding site in its promoter. On the other hand, Bessho et al. established three regulatory elements in the promoter region. Results We show that – with the same half life – the delay system is highly sensitive to changes in the Hill coefficient. A small increase changes the qualitative behaviour of the solutions drastically. There is sustained oscillation and hence the model can no longer explain the disruption of the segmentation clock. On the other hand, the Hill coefficient is correlated with the number of active binding sites, and with the way in which dimers bind to them. In this paper, we adopt response functions in order to estimate Hill coefficients for a variable number of active binding sites. It turns out that three active transcription factor binding sites increase the Hill coefficient by at least 20% as compared to one single active site. Conclusion Our findings lead to the following crucial dichotomy: either Hirata's model is correct for the Hes7 oscillator, in which case at most two binding sites are active in its promoter region; or at least three binding sites are active, in which case Hirata's delay system does not explain the experimental results. Recent experiments by Chen et al. seem to support the former hypothesis, but the discussion is still open.
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Affiliation(s)
- Stefan Zeiser
- Institute of Biomathematics and Biometry, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | - H Volkmar Liebscher
- Department of Mathematics and Computer Science, Ernst-Moritz-Arndt-Universität Greifswald, Jahnstraβe 15a, D-17487 Greifswald, Germany
| | - Hendrik Tiedemann
- Institute of Experimental Genetics, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | - Isabel Rubio-Aliaga
- Institute of Experimental Genetics, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | - Gerhard KH Przemeck
- Institute of Experimental Genetics, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | - Martin Hrabé de Angelis
- Institute of Experimental Genetics, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | - Gerhard Winkler
- Institute of Biomathematics and Biometry, GSF-National Research Centre for Environment and Health, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
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Abstract
Abstract
Juvenile hemochromatosis is a rare autosomal recessive disorder characterized by the early onset of severe iron overload. We report the occurrence of compound heterozygous mutations in hemojuvelin (HJV), including a termination codon, in a patient with juvenile hemochromatosis but no family history of iron disorders. (Blood. 2004;104:2176-2177)
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Affiliation(s)
- Franklin W Huang
- Division of Medical Sciences, Harvard University, Boston, MA, USA
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Groneberg DA, Rubio-Aliaga I, Nickolaus M, Döring F, Fischer A, Daniel H. Direct visualization of peptide uptake activity in the central nervous system of the rat. Neurosci Lett 2004; 364:32-6. [PMID: 15193750 DOI: 10.1016/j.neulet.2004.04.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Revised: 04/06/2004] [Accepted: 04/07/2004] [Indexed: 11/24/2022]
Abstract
Carrier-mediated transport of small peptides and peptidomimetics offers the opportunity for a targeted drug delivery across cell membranes in the central nervous system (CNS). This process is mediated by the proton-coupled transporter PEPT2 which is expressed in glial and choroid plexus cells. In the present studies, an uptake assay was established to visualize directly peptide uptake in intact rat brain slices. Accumulation of a reporter molecule, the fluorophore-labeled dipeptide derivative D-Ala-L-Lys-AMCA, was found in plexus choroideus and glial cells and uptake was inhibited by prototypical PEPT2 substrates, such as glycyl-L-glutamine and cefadroxil. The presence of PEPT2 was confirmed by RT-PCR and Northern blot analysis. This first CNS peptide and drug transport-visualizing assay may be used to examine new compounds which are carried by the proton-driven CNS peptide transporter.
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Affiliation(s)
- David A Groneberg
- Biomedical Research Center, Otto-Heubner-Centre, Charité School of Medicine, Free University Berlin and Humboldt-University, Augustenburger Platz 1 OR1, D-13353 Berlin, Germany
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Rubio-Aliaga I, Boll M, Vogt Weisenhorn DM, Foltz M, Kottra G, Daniel H. The proton/amino acid cotransporter PAT2 is expressed in neurons with a different subcellular localization than its paralog PAT1. J Biol Chem 2003; 279:2754-60. [PMID: 14600155 DOI: 10.1074/jbc.m305556200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The new member of the mammalian amino acid/auxin permease family, PAT2, has been cloned recently and represents an electrogenic proton/amino acid symporter. PAT2 and its paralog, PAT1/LYAAT-1, are transporters for small amino acids such as glycine, alanine, and proline. Our immunodetection studies revealed that the PAT2 protein is expressed in spinal cord and brain. It is found in neuronal cell bodies in the anterior horn in spinal cord and in brain stem, cerebellum, hippocampus, hypothalamus, rhinencephalon, cerebral cortex, and olfactory bulb in the brain. PAT2 is expressed in neurons positive for the N-methyl-d-aspartate subtype glutamate receptor subunit NR1. PAT2 is not found in lysosomes, unlike its paralog PAT1, but is present in the endoplasmic reticulum and recycling endosomes in neurons. PAT2 has a high external proton affinity causing half-maximal transport activation already at a pH of 8.3, suggesting that its activity is most likely not altered by physiological pH changes. Transport of amino acids by PAT2 activity is dependent on membrane potential and can occur bidirectionally; membrane depolarization causes net glycine outward currents. Our data suggest that PAT2 contributes to neuronal transport and sequestration of amino acids such as glycine, alanine, and/or proline, whereby the transport direction is dependent on the sum of the driving forces such as substrate concentration, pH gradient, and membrane potential.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Molecular Nutrition Unit, Technical University of Munich, Hochfeldweg 2, D-85350 Freising-Weihenstephan, Germany
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Abstract
We recently cloned and functionally characterized two novel proton/amino acid transporters (PAT1 and PAT2) from mouse. Here we report the isolation of the corresponding cDNAs of the human orthologues and one additional mouse and human PAT-like transporter cDNA, designated PAT3. The PAT proteins comprise 470 to 483 amino acids. The mouse PAT3 mRNA is expressed in testis of adult mice. In the human and mouse genomes the genes of the PAT transporters (designated SLC36A1-3 and Slc36a1-3, respectively) are clustered on human chromosome 5q33.1 and in the syntenic region of mouse chromosome 11B1.3. PAT-like transporter genes are present as well in the genomes of other eukaryotic organisms such as Drosophila melanogaster and Caenorhabditis elegans. For the PAT3 subtype transporter, we could not yet identify its function. The human PAT1 and PAT2 transporters when functionally expressed in Xenopus laevis oocytes show characteristics similar to those of their mouse counterparts.
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Affiliation(s)
- Michael Boll
- Molecular Nutrition Unit, Institute of Nutritional Sciences, Technical University of Munich, Hochfeldweg 2, D-85350 Freising-Weihenstephan, Germany.
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