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Gordji-Nejad A, Matusch A, Kleedörfer S, Jayeshkumar Patel H, Drzezga A, Elmenhorst D, Binkofski F, Bauer A. Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation. Sci Rep 2024; 14:4937. [PMID: 38418482 PMCID: PMC10902318 DOI: 10.1038/s41598-024-54249-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 02/10/2024] [Indexed: 03/01/2024] Open
Abstract
The inverse effects of creatine supplementation and sleep deprivation on high energy phosphates, neural creatine, and cognitive performances suggest that creatine is a suitable candidate for reducing the negative effects of sleep deprivation. With this, the main obstacle is the limited exogenous uptake by the central nervous system (CNS), making creatine only effective over a long-term diet of weeks. Thus far, only repeated dosing of creatine over weeks has been studied, yielding detectable changes in CNS levels. Based on the hypothesis that a high extracellular creatine availability and increased intracellular energy consumption will temporarily increase the central creatine uptake, subjects were orally administered a high single dose of creatinemonohydrate (0.35 g/kg) while performing cognitive tests during sleep deprivation. Two consecutive 31P-MRS scans, 1H-MRS, and cognitive tests were performed each at evening baseline, 3, 5.5, and 7.5 h after single dose creatine (0.35 g/kg) or placebo during sub-total 21 h sleep deprivation (SD). Our results show that creatine induces changes in PCr/Pi, ATP, tCr/tNAA, prevents a drop in pH level, and improves cognitive performance and processing speed. These outcomes suggest that a high single dose of creatine can partially reverse metabolic alterations and fatigue-related cognitive deterioration.
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Affiliation(s)
- Ali Gordji-Nejad
- Institute of Neuroscience and Medicine (INM-2), Molecular Organization of the Brain, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - Andreas Matusch
- Institute of Neuroscience and Medicine (INM-2), Molecular Organization of the Brain, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Sophie Kleedörfer
- Division of Clinical Cognitive Sciences, Department of Neurology, RWTH Aachen University Hospital, 52074, Aachen, Germany
| | - Harshal Jayeshkumar Patel
- Division of Clinical Cognitive Sciences, Department of Neurology, RWTH Aachen University Hospital, 52074, Aachen, Germany
| | - Alexander Drzezga
- Institute of Neuroscience and Medicine (INM-2), Molecular Organization of the Brain, Forschungszentrum Jülich, 52425, Jülich, Germany
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937, Cologne, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn-Cologne, Germany
| | - David Elmenhorst
- Institute of Neuroscience and Medicine (INM-2), Molecular Organization of the Brain, Forschungszentrum Jülich, 52425, Jülich, Germany
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937, Cologne, Germany
| | - Ferdinand Binkofski
- Division of Clinical Cognitive Sciences, Department of Neurology, RWTH Aachen University Hospital, 52074, Aachen, Germany
- Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Andreas Bauer
- Institute of Neuroscience and Medicine (INM-2), Molecular Organization of the Brain, Forschungszentrum Jülich, 52425, Jülich, Germany
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2
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Tropak MB, Tkachyova I, Gu R, Lee A, Schulze A. Evidence of an intracellular creatine-sensing mechanism that modulates creatine biosynthesis via AGAT expression in human HAP1 cells. Sci Rep 2023; 13:22392. [PMID: 38104212 PMCID: PMC10725494 DOI: 10.1038/s41598-023-49860-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023] Open
Abstract
Cellular homeostasis of creatine (CT), integral part of the energy buffering and transducing system connecting intracellular sites of ATP production and utilization, comprises of mechanisms that increase CT, i.e., biosynthesis and cellular uptake, and CT-lowering processes, such as export and non-enzymatic conversion to creatinine. The biosynthesis of CT is controlled by negative feedback loop via suppression of the rate-limiting enzyme arginine:glycine amidinotransferase (AGAT). Although the regulatory mechanism involved is not well understood, AGAT suppression is successfully used in patients with guanidinoacetate methyltransferase (GAMT) deficiency to reduce the neurotoxic accumulation of the AGAT-mediated guanidinoacetate production by supplementing patients with CT. Utilizing the CT-dependent feedback loop for the upregulation of AGAT expression may well represent a therapeutic target for an additional CT deficiency syndrome, the CT transporter (CrT) defect, for which no effective treatment option is available so far. We have used CRISPR to tag the C-terminus of AGAT with a nanoluc luciferase (NLuc) reporter in HAP1 cells. A biphasic decay of AGAT-NLuc in response to increasing extracellular CT was observed, whereas the decrease in AGAT-NLuc expression was directly proportional to the rise in intracellular CT levels with an approximate IC50 of 1-2 mM. CRISPR generated HAP1 CrT null cells and HAP1 CrT null cells stably expressing a CrT-GFP fusion protein further demonstrated that the biphasic response to extracellular CT is mediated by a high-affinity (Km 9-10 µM) CrT dependent, saturable mechanism and a CrT independent, unsaturable uptake process. The direct response to intracellular CT suggests the existence of an intracellular CT sensing system enabling a dynamic cell response to changing CT concentration that is relevant for cellular CT homeostasis.
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Affiliation(s)
- Michael B Tropak
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Ilona Tkachyova
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Ray Gu
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Alex Lee
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Andreas Schulze
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada.
- Department of Pediatrics, University of Toronto, Toronto, Canada.
- Department of Biochemistry, University of Toronto, Toronto, Canada.
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3
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Philip M, Snow RJ, Della Gatta PA, Callahan DL, Bellofiore N, Salamonsen LA, Palmer KR, Ellery SJ. Aspects of human uterine creatine metabolism during the menstrual cycle and at term pregnancy†. Biol Reprod 2023; 109:839-850. [PMID: 37602666 DOI: 10.1093/biolre/ioad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 07/21/2023] [Accepted: 08/11/2023] [Indexed: 08/22/2023] Open
Abstract
Creatine metabolism likely contributes to energy homeostasis in the human uterus, but whether this organ synthesizes creatine and whether creatine metabolism is adjusted throughout the menstrual cycle and with pregnancy are largely unknown. This study determined endometrial protein expression of creatine-synthesizing enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT), creatine kinase (CKBB), and the creatine transporter (SLC6A8) throughout the menstrual cycle in fertile and primary infertile women. It also characterized creatine metabolism at term pregnancy, measuring aspects of creatine metabolism in myometrial and decidual tissue. In endometrial samples, AGAT, GAMT, SLC6A8, and CKBB were expressed in glandular and luminal epithelial cells. Except for SLC6A8, the other proteins were also located in stromal cells. Irrespective of fertility, AGAT, GAMT, and SLC6A8 high-intensity immunohistochemical staining was greatest in the early secretory phase of the menstrual cycle. During the proliferative phase, staining for SLC6A8 protein was greater (P = 0.01) in the primary infertile compared with the fertile group. Both layers of the term pregnant uterus contained creatine, phosphocreatine, guanidinoacetic acid, arginine, glycine, and methionine; detectable gene and protein expression of AGAT, GAMT, CKBB, and ubiquitous mitochondrial CK (uMt-CK); and gene expression of SLC6A8. The proteins AGAT, GAMT, CKBB, and SLC6A8 were uniformly distributed in the myometrium and localized to the decidual glands. In conclusion, endometrial tissue has the capacity to produce creatine and its capacity is highest around the time of fertilization and implantation. Both layers of the term pregnant uterus also contained all the enzymatic machinery and substrates of creatine metabolism.
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Affiliation(s)
- Mamatha Philip
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Rodney J Snow
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Paul A Della Gatta
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| | - Damien L Callahan
- Centre for Molecular and Medical Research, School of Life and Environmental Sciences, Deakin University, Melbourne, VIC, Australia
| | - Nadia Bellofiore
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC, Australia
| | - Lois A Salamonsen
- The Centre for Reproductive Health, Hudson Institute of Medical Research, Clayton, VIC, Australia
| | - Kirsten R Palmer
- Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC, Australia
| | - Stacey J Ellery
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC, Australia
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4
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Jomura R, Akanuma SI, Tachikawa M, Hosoya KI. SLC6A and SLC16A family of transporters: Contribution to transport of creatine and creatine precursors in creatine biosynthesis and distribution. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183840. [PMID: 34921896 DOI: 10.1016/j.bbamem.2021.183840] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/06/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022]
Abstract
Creatine (Cr) is needed to maintain high energy levels in cells. Since Cr plays reportedly a critical role in neurodevelopment and the immune system, Cr dynamics should be strictly regulated to control these physiological events. This review focuses on the role of transporters that recognize Cr and/or Cr precursors. Our previous studies revealed physiological roles of SLC6A and SLC16A family transporters in Cr dynamics. Creatine transporter (CRT/SLC6A8) contributes to the influx transport of Cr in Cr distribution. γ-Aminobutyric acid transporter 2 (GAT2/SLC6A13) mediates incorporation of guanidinoacetate (GAA), a Cr precursor, in the process of Cr biosynthesis. Monocarboxylate transporter 12 (MCT12/SLC16A12) functions as an efflux transporter for Cr and GAA, and contributes to the process of Cr biosynthesis. Accordingly, the SLC6A and SLC16A family of transporters play important roles in the process of Cr biosynthesis and distribution via permeation of Cr and Cr precursors across the plasma membrane.
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Affiliation(s)
- Ryuta Jomura
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| | - Shin-Ichi Akanuma
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| | - Masanori Tachikawa
- Graduate School of Biomedical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
| | - Ken-Ichi Hosoya
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Ghirardini E, Calugi F, Sagona G, Di Vetta F, Palma M, Battini R, Cioni G, Pizzorusso T, Baroncelli L. The Role of Preclinical Models in Creatine Transporter Deficiency: Neurobiological Mechanisms, Biomarkers and Therapeutic Development. Genes (Basel) 2021; 12:genes12081123. [PMID: 34440297 PMCID: PMC8392480 DOI: 10.3390/genes12081123] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/12/2022] Open
Abstract
Creatine (Cr) Transporter Deficiency (CTD) is an X-linked metabolic disorder, mostly caused by missense mutations in the SLC6A8 gene and presenting with intellectual disability, autistic behavior, and epilepsy. There is no effective treatment for CTD and patients need lifelong assistance. Thus, the research of novel intervention strategies is a major scientific challenge. Animal models are an excellent tool to dissect the disease pathogenetic mechanisms and drive the preclinical development of therapeutics. This review illustrates the current knowledge about Cr metabolism and CTD clinical aspects, with a focus on mainstay diagnostic and therapeutic options. Then, we discuss the rodent models of CTD characterized in the last decade, comparing the phenotypes expressed within clinically relevant domains and the timeline of symptom development. This analysis highlights that animals with the ubiquitous deletion/mutation of SLC6A8 genes well recapitulate the early onset and the complex pathological phenotype of the human condition. Thus, they should represent the preferred model for preclinical efficacy studies. On the other hand, brain- and cell-specific conditional mutants are ideal for understanding the basis of CTD at a cellular and molecular level. Finally, we explain how CTD models might provide novel insight about the pathogenesis of other disorders, including cancer.
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MESH Headings
- Animals
- Biomarkers/metabolism
- Brain Diseases, Metabolic, Inborn/metabolism
- Brain Diseases, Metabolic, Inborn/pathology
- Brain Diseases, Metabolic, Inborn/therapy
- Central Nervous System/pathology
- Creatine/deficiency
- Creatine/metabolism
- Disease Models, Animal
- Humans
- Mental Retardation, X-Linked/metabolism
- Mental Retardation, X-Linked/pathology
- Mental Retardation, X-Linked/therapy
- Mice
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/metabolism
- Rats
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Affiliation(s)
- Elsa Ghirardini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
| | - Francesco Calugi
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Giulia Sagona
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Federica Di Vetta
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Biology, University of Pisa, I-56126 Pisa, Italy
| | - Martina Palma
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Roberta Battini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Clinical and Experimental Medicine, University of Pisa, I-56126 Pisa, Italy
| | - Giovanni Cioni
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Clinical and Experimental Medicine, University of Pisa, I-56126 Pisa, Italy
| | - Tommaso Pizzorusso
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Laura Baroncelli
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Correspondence:
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Ostojic SM. Modulation of CT1 Function: From Klotho Protein to Ammonia and Beyond. Front Nutr 2021; 8:660021. [PMID: 34041260 PMCID: PMC8143434 DOI: 10.3389/fnut.2021.660021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/23/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Sergej M Ostojic
- FSPE Applied Bioenergetics Lab, University of Novi Sad, Novi Sad, Serbia
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Effects of guanidinoacetic acid and coated folic acid supplementation on growth performance, nutrient digestion and hepatic gene expression in Angus bulls. Br J Nutr 2020; 126:510-517. [PMID: 33143765 DOI: 10.1017/s0007114520004341] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
To evaluate the impacts of guanidinoacetic acid (GAA) and coated folic acid (CFA) on growth performance, nutrient digestion and hepatic gene expression, fifty-two Angus bulls were assigned to four groups in a 2 × 2 factor experimental design. The CFA of 0 or 6 mg/kg dietary DM folic acid was supplemented in diets with GAA of 0 (GAA-) or 0·6 g/kg DM (GAA+), respectively. Average daily gain (ADG), feed efficiency and hepatic creatine concentration increased with GAA or CFA addition, and the increased magnitude of these parameters was greater for addition of CFA in GAA- diets than in GAA+ diets. Blood creatine concentration increased with GAA or CFA addition, and greater increase was observed when CFA was supplemented in GAA+ diets than in GAA- diets. DM intake was unchanged, but rumen total SCFA concentration and digestibilities of DM, crude protein, neutral-detergent fibre and acid-detergent fibre increased with the addition of GAA or CFA. Acetate:propionate ratio was unaffected by GAA, but increased for CFA addition. Increase in blood concentrations of albumin, total protein and insulin-like growth factor-1 (IGF-1) was observed for GAA or CFA addition. Blood folate concentration was decreased by GAA, but increased with CFA addition. Hepatic expressions of IGF-1, phosphoinositide 3-kinase, protein kinase B, mammalian target of rapamycin and ribosomal protein S6 kinase increased with GAA or CFA addition. Results indicated that the combined supplementation of GAA and CFA could not cause ADG increase more when compared with GAA or CFA addition alone.
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Hall CHT, Lee JS, Murphy EM, Gerich ME, Dran R, Glover LE, Abdulla ZI, Skelton MR, Colgan SP. Creatine Transporter, Reduced in Colon Tissues From Patients With Inflammatory Bowel Diseases, Regulates Energy Balance in Intestinal Epithelial Cells, Epithelial Integrity, and Barrier Function. Gastroenterology 2020; 159:984-998.e1. [PMID: 32433978 PMCID: PMC7891846 DOI: 10.1053/j.gastro.2020.05.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 05/04/2020] [Accepted: 05/11/2020] [Indexed: 01/03/2023]
Abstract
BACKGROUND & AIMS Patients with inflammatory bowel diseases (IBDs) have intestinal barrier dysfunction. Creatine regulates energy distribution within cells and reduces the severity of colitis in mice. We studied the functions of the creatine transporter solute carrier family 6 member 8 (SLC6A8, also called CRT) in intestinal epithelial cells (IECs) and mice, and we measured levels in mucosal biopsies from patients with IBD. METHODS Colon biopsy specimens from patients with IBD (30 with Crohn's disease and 27 with ulcerative colitis) and 30 patients without IBD (control individuals) and colon tissues from mice (with and without disruption of Crt) were analyzed by immunofluorescence, immunoblots, and/or quantitative reverse-transcription polymerase chain reaction (qRT-PCR). CRT was knocked down or overexpressed in T84 cells, which were analyzed by immunofluorescence, immunoblots, high-performance liquid chromatography (to measure creatine levels), qRT-PCR, transepithelial electrical resistance, barrier function, actin localization, wound healing, mitochondrial oxygen consumption, and glycolysis extracellular acidification rate assays. Organoids from colon cells of CRT-knockout mice and control mice were analyzed by qRT-PCR, immunoblot, and transepithelial electrical resistance. RESULTS CRT localized around tight junctions (TJs) of T84 IECs. In analyses of IECs with CRT knockdown or overexpression, we found that CRT regulates intracellular creatine, barrier formation, and wound healing. CRT-knockout organoids also had diminished barrier formation. In the absence of adequate creatine, IECs transition toward a stressed, glycolysis-predominant form of metabolism; this resulted in leaky TJs and mislocalization of actin and TJ proteins. Colon tissues from patients with IBD had reduced levels of CRT messenger RNA compared with those from control individuals. CONCLUSIONS In an analysis of IEC cell lines and colonoids derived from CRT-knockout mice, we found that CRT regulates energy balance in IECs and thereby epithelial integrity and barrier function. Mucosal biopsy specimens from patients with ulcerative colitis and inactive Crohn's disease have lower levels of CRT, which might contribute to the reduced barrier function observed in patients with IBD.
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Affiliation(s)
- Caroline H T Hall
- Division of Gastroenterology, Hepatology and Nutrition, Children's Hospital Colorado, Aurora, Colorado; Mucosal Inflammation Program, University of Colorado, Aurora, Colorado
| | - J Scott Lee
- Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado
| | - Emily M Murphy
- Division of Gastroenterology, Hepatology and Nutrition, Children's Hospital Colorado, Aurora, Colorado; Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado
| | - Mark E Gerich
- Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado
| | - Rachael Dran
- Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado
| | - Louis E Glover
- Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado; School of Biochemistry and Immunology, Trinity College Dublin, Ireland
| | - Zuhair I Abdulla
- Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio; Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, Ohio
| | - Matthew R Skelton
- Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio; Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, Ohio
| | - Sean P Colgan
- Mucosal Inflammation Program, University of Colorado, Aurora, Colorado; Division of Gastroenterology and Hepatology, University of Colorado, Aurora, Colorado.
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Ellery SJ, Murthi P, Davies-Tuck ML, Della Gatta PA, May AK, Kowalski GM, Callahan DL, Bruce CR, Alers NO, Miller SL, Erwich JJHM, Wallace EM, Walker DW, Dickinson H, Snow RJ. Placental creatine metabolism in cases of placental insufficiency and reduced fetal growth. Mol Hum Reprod 2020; 25:495-505. [PMID: 31323678 DOI: 10.1093/molehr/gaz039] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/16/2019] [Accepted: 06/27/2019] [Indexed: 11/14/2022] Open
Abstract
Creatine is a metabolite involved in cellular energy homeostasis. In this study, we examined placental creatine content, and expression of the enzymes required for creatine synthesis, transport and the creatine kinase reaction, in pregnancies complicated by low birthweight. We studied first trimester chorionic villus biopsies (CVBs) of small for gestational age (SGA) and appropriately grown infants (AGA), along with third trimester placental samples from fetal growth restricted (FGR) and healthy gestation-matched controls. Placental creatine and creatine precursor (guanidinoacetate-GAA) levels were measured. Maternal and cord serum from control and FGR pregnancies were also analyzed for creatine concentration. mRNA expression of the creatine transporter (SLC6A8); synthesizing enzymes arginine:glycine aminotransferase (GATM) and guanidinoacetate methyltransferase (GAMT); mitochondrial (mtCK) and cytosolic (BBCK) creatine kinases; and amino acid transporters (SLC7A1 & SLC7A2) was assessed in both CVBs and placental samples. Protein levels of AGAT (arginine:glycine aminotransferase), GAMT, mtCK and BBCK were also measured in placental samples. Key findings; total creatine content of the third trimester FGR placentae was 43% higher than controls. The increased creatine content of placental tissue was not reflected in maternal or fetal serum from FGR pregnancies. Tissue concentrations of GAA were lower in the third trimester FGR placentae compared to controls, with lower GATM and GAMT mRNA expression also observed. No differences in the mRNA expression of GATM, GAMT or SLC6A8 were observed between CVBs from SGA and AGA pregnancies. These results suggest placental creatine metabolism in FGR pregnancies is altered in late gestation. The relevance of these changes on placental bioenergetics should be the focus of future investigations.
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Affiliation(s)
- Stacey J Ellery
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - Padma Murthi
- Department of Physiology, Monash University, Clayton, Victoria; Department of Maternal-Fetal Medicine, Pregnancy Research Centre, Royal Women's Hospital and Department of Obstetrics and Gynaecology, University of Melbourne, Parkville, Victoria, Australia
| | - Miranda L Davies-Tuck
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - Paul A Della Gatta
- Institute for Physical Activity and Nutrition, School of Exercise Sciences, Deakin, Geelong, Australia
| | - Anthony K May
- Institute for Physical Activity and Nutrition, School of Exercise Sciences, Deakin, Geelong, Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise Sciences, Deakin, Geelong, Australia
| | - Damien L Callahan
- Centre for Cellular and Molecular Biology, School of Life and Environmental Science, Deakin University, Burwood, Melbourne, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise Sciences, Deakin, Geelong, Australia
| | - Nicole O Alers
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - Jan Jaap H M Erwich
- Dept of Obstetrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Euan M Wallace
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - David W Walker
- School of Health & Biomedical Sciences, RMIT University, Melbourne, Australia
| | - Hayley Dickinson
- The Ritchie Centre, Hudson Institute of Medical Research, and Department of Obstetrics & Gynaecology, Monash University, Melbourne, Australia
| | - Rod J Snow
- Institute for Physical Activity and Nutrition, School of Exercise Sciences, Deakin, Geelong, Australia
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10
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Luo D, Edwards S, Smeuninx B, McKendry J, Nishimura Y, Perkins M, Philp A, Joanisse S, Breen L. Immobilization Leads to Alterations in Intracellular Phosphagen and Creatine Transporter Content in Human Skeletal Muscle. Am J Physiol Cell Physiol 2020; 319:C34-C44. [PMID: 32374680 DOI: 10.1152/ajpcell.00072.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The role of dysregulated intracellular creatine metabolism in disuse atrophy is unknown. In this study, skeletal muscle biopsy samples were obtained after 7-days of unilateral leg immobilization (IMMOB) and the non-immobilized control limb (CTRL) of 15 healthy males (23.1 ± 3.5 yrs). Samples were analyzed for fibre-type cross-sectional area (CSA) and creatine transporter (CreaT) at the cell membrane periphery (MEM) or intracellular (INT) areas, via immunoflouresence microscopy. Creatine kinase (CK) and AMP-activated protein kinase (AMPK) were determined via immunoblot. PCr, Cr and ATP were measured via enzymatic analysis. Body composition and maximal isometric knee extensor strength were assessed before and after disuse. Leg strength and fat-free mass were reduced in IMMOB (~32% and 4%, respectively; P<0.01 for both). Type II fibre CSA was smaller (~12%; P=0.028) and intramuscular PCr lower (~13%; P=0.015) in IMMOB vs. CTRL. CreaT protein was greater in Type I fibres in both limbs (P<0.01). CreaT was greater in IMMOB vs. CTRL (P < 0.01) and inversely associated with PCr concentration in both limbs (P < 0.05). MEM CreaT was greater than the INT CreaT in Type I and II fibres of both limbs (~14% for both; P<0.01 for both). Type I fibre CreaT tended to be greater in IMMOB vs. CTRL (P=0.074). CK was greater, and phospho-to-total AMPKThr172 tended to be greater, in IMMOB vs. CTRL (P=0.013 and 0.051, respectively). These findings suggest that modulation of intracellular creatine metabolism is an adaptive response to immobilisation in young healthy skeletal muscle.
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Affiliation(s)
- Dan Luo
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, United Kingdom
| | - Sophie Edwards
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, United Kingdom
| | - Benoit Smeuninx
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, United Kingdom
| | - James McKendry
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK; Department of Kinesiology, McMaster University, Ontario, Canada
| | - Yusuke Nishimura
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, United Kingdom
| | - Molly Perkins
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK; School of Sport and Health Sciences, University of Exeter, UK
| | - Andrew Philp
- Garvan Institute of Medical Research, Sydney, Australia; St Vincents Medical School, UNSW Medicine, UNSW Sydney, Sydney, Australia
| | - Sophie Joanisse
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK; Department of Kinesiology, McMaster University, Ontario, Canada
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK; MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, UK
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11
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Reicher N, Epstein T, Gravitz D, Cahaner A, Rademacher M, Braun U, Uni Z. From broiler breeder hen feed to the egg and embryo: The molecular effects of guanidinoacetate supplementation on creatine transport and synthesis. Poult Sci 2020; 99:3574-3582. [PMID: 32616254 PMCID: PMC7597819 DOI: 10.1016/j.psj.2020.03.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 01/26/2020] [Accepted: 03/27/2020] [Indexed: 01/25/2023] Open
Abstract
Supplementation of broiler breeder hens with beneficial additives bears great potential for affecting nutrient deposition into the fertile egg. Guanidinoacetate (GAA) is the endogenous precursor of creatine that is used as a feed additive for improving cellular energy metabolism in animal nutrition. In the present study, we have investigated whether GAA supplementation in broiler breeder feed affects creatine deposition into the hatching egg and molecular mechanisms of creatine transport and synthesis within hens and their progeny. For this, broiler breeder hens of 47 wk of age were supplemented with 0.15% GAA for 15 wk, and samples from their tissues, hatching eggs and progeny were compared with those of control, nonsupplemented hens. A significant increase in creatine content was found within the yolk and albumen of hatching eggs obtained from the GAA group, compared with the control group. The GAA group exhibited a significant increased creatine transporter gene expression compared with the control group in their small intestines and oviduct. In GAA group progeny, a significant decrease in creatine transporter expression at embryonic day 19 and day of hatch was found, compared with control group progeny. At the day of hatch, creatine synthesis genes (arginine glycine amidinotransferase and guanidinoacetate N-methyltransferase) exhibited significant decrease in expression in the GAA group progeny compared with control group progeny. These results indicate that GAA supplementation in broiler breeder feed increases its absorbance and deposition into hatching eggs, subsequently affecting GAA and creatine absorbance and synthesis within broiler progeny.
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Affiliation(s)
- Naama Reicher
- Department of Animal Science, The Robert H. Smith, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Tomer Epstein
- Department of Animal Science, The Robert H. Smith, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Dor Gravitz
- Department of Animal Science, The Robert H. Smith, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Avigdor Cahaner
- Department of Animal Science, The Robert H. Smith, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | | | - Ulrike Braun
- AlzChem Trostberg GmbH, Trostberg 83308, Germany
| | - Zehava Uni
- Department of Animal Science, The Robert H. Smith, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
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12
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Turchetti G, Paz C. Aristotelia chilensis (Mol.) Stuntz: A Natural Source of Bioactive Compounds. CURRENT TRADITIONAL MEDICINE 2019. [DOI: 10.2174/2215083804666181002095249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aristotelia chilensis (Mol.) Stuntz, commonly called “maqui” is a native tree of
Chile considered sacred for the Mapuche people. The fruits are sweet blackberries with a
high concentration of polyphenols which stain the hands and mouth when eaten. The
Mapuche people use it for creating "chicha" an alcoholic beverage, while leaves are used to
treat infected wounds, inflammation and ulcers. In this review, we will give an overview of
the pharmacology reported for the plant and molecules isolated from leaves and fruits, with
the scope of giving a better understanding of the potential of this tree.
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Affiliation(s)
- Giovanni Turchetti
- Laboratory of Plant Cytology and Biotechnology, Department for the Innovation in Biological, Agro-food and Forest systems, DIBAF, Tuscia University, Viterbo, Italy
| | - Cristian Paz
- Departamento de Ciencias Quimicas y Recursos Naturales, BIOREN, Universidad de La Frontera, Temuco, Chile
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13
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Ibrahim D, El Sayed R, Abdelfattah-Hassan A, Morshedy AM. Creatine or guanidinoacetic acid? Which is more effective at enhancing growth, tissue creatine stores, quality of meat, and genes controlling growth/myogenesis in Mulard ducks. JOURNAL OF APPLIED ANIMAL RESEARCH 2019. [DOI: 10.1080/09712119.2019.1590205] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Doaa Ibrahim
- Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Rania El Sayed
- Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Ahmed Abdelfattah-Hassan
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - A. M. Morshedy
- Department of Food Control, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
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14
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Gómez-Canela C, Prats E, Lacorte S, Raldúa D, Piña B, Tauler R. Metabolomic changes induced by nicotine in adult zebrafish skeletal muscle. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 164:388-397. [PMID: 30142605 DOI: 10.1016/j.ecoenv.2018.08.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 08/11/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
Acute exposure to nicotinic agonists induces myotoxicity in zebrafish embryos. The main goal of this work was to evaluate the potential myotoxicity of nicotine acetylcholine receptor agonists on adult zebrafish muscle tissue by using nicotine as a model compound. Liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) datasets were processed with different chemometric tools based on the selection of Regions of Interest (ROI) and Multivariate Curve-Resolution (ROI-MCR procedure) Alternating Least Squares (ALS) for the analysis of different exposure experiments. Analysis of Variance Simultaneous Component Analysis (ASCA) of changes on metabolite peak profile areas showed significant nicotine concentration and exposure time-dependent changes, clearly differentiating between exposed and non-exposed samples and between short (2 h) and long exposure times (6 h or 24 h). Most of the changes observed in the concentrations of different metabolites are probably secondary to the observed hyperlocomotion, as they have been also observed in humans after strenuous muscular exercise. The absence of myotoxicity might be related with the reduced calcium permeability of adult muscle-type nicotinic acetylcholine receptors (nAChRs).
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Affiliation(s)
- Cristian Gómez-Canela
- Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain.
| | - Eva Prats
- Centre d'Investigació I Desenvolupament, CID-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Silvia Lacorte
- Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Demetrio Raldúa
- Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Benjamí Piña
- Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
| | - Romà Tauler
- Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Catalonia, Spain
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15
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Santacruz L, Arciniegas AJL, Darrabie M, Mantilla JG, Baron RM, Bowles DE, Mishra R, Jacobs DO. Hypoxia decreases creatine uptake in cardiomyocytes, while creatine supplementation enhances HIF activation. Physiol Rep 2018; 5:5/16/e13382. [PMID: 28821596 PMCID: PMC5582266 DOI: 10.14814/phy2.13382] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 07/18/2017] [Indexed: 12/23/2022] Open
Abstract
Creatine (Cr), phosphocreatine (PCr), and creatine kinases (CK) comprise an energy shuttle linking ATP production in mitochondria with cellular consumption sites. Myocytes cannot synthesize Cr: these cells depend on uptake across the cell membrane by a specialized creatine transporter (CrT) to maintain intracellular Cr levels. Hypoxia interferes with energy metabolism, including the activity of the creatine energy shuttle, and therefore affects intracellular ATP and PCr levels. Here, we report that exposing cultured cardiomyocytes to low oxygen levels rapidly diminishes Cr transport by decreasing Vmax and Km. Pharmacological activation of AMP‐activated kinase (AMPK) abrogated the reduction in Cr transport caused by hypoxia. Cr supplementation increases ATP and PCr content in cardiomyocytes subjected to hypoxia, while also significantly augmenting the cellular adaptive response to hypoxia mediated by HIF‐1 activation. Our results indicate that: (1) hypoxia reduces Cr transport in cardiomyocytes in culture, (2) the cytoprotective effects of Cr supplementation are related to enhanced adaptive physiological responses to hypoxia mediated by HIF‐1, and (3) Cr supplementation increases the cellular ATP and PCr content in RNCMs exposed to hypoxia.
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Affiliation(s)
- Lucia Santacruz
- Department of Molecular Biology and Biochemistry, The University of Texas Medical Branch, Galveston, Texas .,Department of Natural Sciences, Bowie State University, Bowie, Maryland
| | - Antonio Jose Luis Arciniegas
- Department of Medicine, Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | | | - Rebecca M Baron
- Department of Medicine, Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Dawn E Bowles
- Duke University Medical Center, Durham, North Carolina
| | | | - Danny O Jacobs
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas.,Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas
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16
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Tomcik KA, Camera DM, Bone JL, Ross ML, Jeacocke NA, Tachtsis B, Senden J, VAN Loon LJC, Hawley JA, Burke LM. Effects of Creatine and Carbohydrate Loading on Cycling Time Trial Performance. Med Sci Sports Exerc 2018; 50:141-150. [PMID: 28806275 DOI: 10.1249/mss.0000000000001401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Creatine (Cr) and carbohydrate loadings are dietary strategies used to enhance exercise capacity. This study examined the metabolic and performance effects of a combined CR and CHO loading regiment on time trial (TT) cycling bouts. METHODS Eighteen well-trained (~65 mL·kg·min V˙O2peak) men completed three performance trials (PT) that comprised a 120-km cycling TT interspersed with alternating 1- and 4-km sprints (six sprints each) performed every 10 km followed by an inclined ride to fatigue (~90% V˙O2peak). Subjects were pair matched into either CR-loaded (20 g·d for 5 d + 3 g·d for 9 d) or placebo (PLA) groups (n = 9) after the completion of PT1. All subjects undertook a crossover application of the carbohydrate interventions, consuming either moderate (6 g·kg body mass (BM) per day; MOD) or CHO-loaded (12 g·kg BM·d; LOAD) diets before PT2 and PT3. Muscle biopsies were taken before PT1, 18 h after PT1, and before both PT2 and PT3. RESULTS No significant differences in overall TT or inclined ride times were observed between intervention groups. PLA + LOAD improved power above baseline (P < 0.05) during the final 1-km sprint, whereas CR + MOD and CR + LOAD improved power (P < 0.05) during the final 4-km sprint. Greater power was achieved with MOD and LOAD compared with baseline with PLA (P < 0.05). CR increased pre-PT BM compared with PLA (+1.54% vs +0.99% from baseline). CR + LOAD facilitated greater [total CR] (P < 0.05 vs baseline) and muscle [glycogen] (P < 0.01 vs baseline and MOD) compared with PLA + LOAD. Mechanistic target of rapamycin decreased from baseline after glycogen depletion (~30%; P < 0.05). CONCLUSIONS Power output in the closing sprints of exhaustive TT cycling increased with CR ingestion despite a CR-mediated increase in weight. CR cosupplemented with carbohydrates may therefore be beneficial strategy for late-stage breakaway moments in endurance events.
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Affiliation(s)
- Kristyen A Tomcik
- 1Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, AUSTRALIA; 2Sports Nutrition, Australian Institute of Sport, Belconnen, Australian Capital Territory, AUSTRALIA; 3NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, THE NETHERLANDS; and 4Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM
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17
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Karlíková R, Mičová K, Najdekr L, Gardlo A, Adam T, Majerová P, Friedecký D, Kováč A. Metabolic status of CSF distinguishes rats with tauopathy from controls. ALZHEIMERS RESEARCH & THERAPY 2017; 9:78. [PMID: 28934963 PMCID: PMC5609022 DOI: 10.1186/s13195-017-0303-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 08/31/2017] [Indexed: 11/17/2022]
Abstract
Background Tauopathies represent heterogeneous groups of neurodegenerative diseases that are characterised by abnormal deposition of the microtubule-associated protein tau. Alzheimer’s disease is the most prevalent tauopathy, affecting more than 35 million people worldwide. In this study we investigated changes in metabolic pathways associated with tau-induced neurodegeneration. Methods Cerebrospinal fluid (CSF), plasma and brain tissue were collected from a transgenic rat model for tauopathies and from age-matched control animals. The samples were analysed by targeted and untargeted metabolomic methods using high-performance liquid chromatography coupled to mass spectrometry. Unsupervised and supervised statistical analysis revealed biochemical changes associated with the tauopathy process. Results Energy deprivation and potentially neural apoptosis were reflected in increased purine nucleotide catabolism and decreased levels of citric acid cycle intermediates and glucose. However, in CSF, increased levels of citrate and aconitate that can be attributed to glial activation were observed. Other significant changes were found in arginine and phosphatidylcholine metabolism. Conclusions Despite an enormous effort invested in development of biomarkers for tauopathies during the last 20 years, there is no clinically used biomarker or assay on the market. One of the most promising strategies is to create a panel of markers (e.g., small molecules, proteins) that will be continuously monitored and correlated with patients’ clinical outcome. In this study, we identified several metabolic changes that are affected during the tauopathy process and may be considered as potential markers of tauopathies in humans. Electronic supplementary material The online version of this article (doi:10.1186/s13195-017-0303-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Radana Karlíková
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Kateřina Mičová
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Lukáš Najdekr
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Alžběta Gardlo
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Tomáš Adam
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic.,Laboratory for Inherited Metabolic Disorders, Faculty of Medicine and Dentistry, Palacký University Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Petra Majerová
- Institute of Neuroimmunology, Slovak Academy of Sciences, Dúbravská cesta 9, 84510, Bratislava, Slovak Republic.,AXON Neuroscience R&D, Dvořákovo nábrežie 10, 811 02, Bratislava, Slovak Republic
| | - David Friedecký
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hněvotínská 5, 779 00, Olomouc, Czech Republic.,Department of Clinical Biochemistry, University Hospital Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic.,Laboratory for Inherited Metabolic Disorders, Faculty of Medicine and Dentistry, Palacký University Olomouc, I. P. Pavlova 6, 775 20, Olomouc, Czech Republic
| | - Andrej Kováč
- Institute of Neuroimmunology, Slovak Academy of Sciences, Dúbravská cesta 9, 84510, Bratislava, Slovak Republic. .,AXON Neuroscience R&D, Dvořákovo nábrežie 10, 811 02, Bratislava, Slovak Republic.
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Abstract
Creatine is a principle component of the creatine kinase (CK) phosphagen system common to all vertebrates. It is found in excitable cells, such as cardiomyocytes, where it plays an important role in the buffering and transport of chemical energy to ensure that supply meets the dynamic demands of the heart. Multiple components of the CK system, including intracellular creatine levels, are reduced in heart failure, while ischaemia and hypoxia represent acute crises of energy provision. Elevation of myocardial creatine levels has therefore been suggested as potentially beneficial, however, achieving this goal is not trivial. This mini-review outlines the evidence in support of creatine elevation and critically examines the pharmacological approaches that are currently available. In particular, dietary creatine-supplementation does not sufficiently elevate creatine levels in the heart due to subsequent down-regulation of the plasma membrane creatine transporter (CrT). Attempts to increase passive diffusion and bypass the CrT, e.g. via creatine esters, have yet to be tested in the heart. However, studies in mice with genetic overexpression of the CrT demonstrate proof-of-principle that elevated creatine protects the heart from ischaemia-reperfusion injury. This suggests activation of the CrT as a major unmet pharmacological target. However, translation of this finding to the clinic will require a greater understanding of CrT regulation in health and disease and the development of small molecule activators.
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Affiliation(s)
| | | | | | - Craig A Lygate
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Headington OX3 7BN, UK.
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19
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Santacruz L, Jacobs DO. Structural correlates of the creatine transporter function regulation: the undiscovered country. Amino Acids 2016; 48:2049-55. [PMID: 26951207 DOI: 10.1007/s00726-016-2206-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 02/23/2016] [Indexed: 10/22/2022]
Abstract
Creatine (Cr) and phosphocreatine constitute an energy shuttle that links ATP production in mitochondria to subcellular locations of ATP consumption. Cells in tissues that are reliant on this energy shuttle, such as myocytes and neurons, appear to have very limited ability to synthesize creatine. Therefore, these cells depend on Cr uptake across the cell membrane by a specialized creatine transporter (CrT solute carrier SLC6A8) in order to maintain intracellular creatine levels. Cr supplementation has been shown to have a beneficial effect in numerous in vitro and in vivo models, particularly in cases of oxidative stress, and is also widely used by athletes as a performance enhancement nutraceutical. Intracellular creatine content is maintained within narrow limits. However, the physiological and cellular mechanisms that mediate Cr transport during health and disease (such as cardiac failure) are not understood. In this narrative mini-review, we summarize the last three decades of research on CrT structure, function and regulation.
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Affiliation(s)
- Lucia Santacruz
- Department of Biochemistry and Molecular Biology, University of Texas, Medical Branch, 301 University Boulevard, Galveston, TX, USA.
| | - Danny O Jacobs
- Department of Biochemistry and Molecular Biology, University of Texas, Medical Branch, 301 University Boulevard, Galveston, TX, USA.,Departament of Surgery and the institute for Translational Sciences, University of Texas, Medical Branch, Galveston, USA
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20
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Balestrino M, Sarocchi M, Adriano E, Spallarossa P. Potential of creatine or phosphocreatine supplementation in cerebrovascular disease and in ischemic heart disease. Amino Acids 2016; 48:1955-67. [DOI: 10.1007/s00726-016-2173-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/06/2016] [Indexed: 12/16/2022]
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Tomcik KA, Smiles WJ, Camera DM, Hügel HM, Hawley JA, Watts R. Fenugreek increases insulin-stimulated creatine content in L6C11 muscle myotubes. Eur J Nutr 2016; 56:973-979. [PMID: 26732502 DOI: 10.1007/s00394-015-1145-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 12/17/2015] [Indexed: 11/28/2022]
Abstract
PURPOSE Creatine uptake by muscle cells is increased in the presence of insulin. Accordingly, compounds with insulin-like actions may also augment creatine uptake. The aim of this study was to investigate whether Trigonella foenum-graecum (fenugreek), an insulin mimetic, increases total intracellular creatine levels in vitro. METHODS Total cellular creatine content was measured fluorometrically in L6C11 muscle myotubes treated for 1, 4, and 24 h with 0.5 mM creatine (CR), CR and 20 μg/mL fenugreek seed extract (CR + FEN), CR and 100 nM insulin (CR + INS), and CR + INS + FEN (n = 6 per treatment group). Alterations in the expression of the sodium- and chloride-dependent creatine transporter, SLC6A8, and key signaling proteins in the PI3-K/Akt pathway were determined. RESULTS Compared to control (CON), CR + INS + FEN increased total creatine content after 4 h (P < 0.05), whereas all conditions increased SLC6A8 protein expression above CON at this time (P < 0.05). Changes in insulin signaling were demonstrated via increases in AktThr308 phosphorylation, with CR + INS > CON and CR at 1 h (P < 0.05) and with CR + INS + FEN > CON, CR, and CR + INS at 4 h (P < 0.05). In contrast, no changes in PKCζ/λ or GLUT4 phosphorylation were detected. CONCLUSION Fenugreek, when combined with insulin, modulates creatine content via a mechanism which is independent of the activity of SLC6A8, suggesting that an alternative mechanism is responsible for the regulation and facilitation of insulin-mediated creatine uptake in skeletal muscle cells.
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Affiliation(s)
- Kristyen A Tomcik
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, 3065, Australia
| | - William J Smiles
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, 3065, Australia
| | - Donny M Camera
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, 3065, Australia
| | - Helmut M Hügel
- School of Applied Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, Australia
| | - John A Hawley
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, 3065, Australia. .,Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
| | - Rani Watts
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, 3065, Australia
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Joncquel-Chevalier Curt M, Voicu PM, Fontaine M, Dessein AF, Porchet N, Mention-Mulliez K, Dobbelaere D, Soto-Ares G, Cheillan D, Vamecq J. Creatine biosynthesis and transport in health and disease. Biochimie 2015; 119:146-65. [DOI: 10.1016/j.biochi.2015.10.022] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/27/2015] [Indexed: 12/31/2022]
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McBreairty LE, Robinson JL, Furlong KR, Brunton JA, Bertolo RF. Guanidinoacetate is more effective than creatine at enhancing tissue creatine stores while consequently limiting methionine availability in Yucatan miniature pigs. PLoS One 2015; 10:e0131563. [PMID: 26110793 PMCID: PMC4482513 DOI: 10.1371/journal.pone.0131563] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 06/03/2015] [Indexed: 01/15/2023] Open
Abstract
Creatine (Cr) is an important high-energy phosphate buffer in tissues with a high energy demand such as muscle and brain and is consequently a highly consumed nutritional supplement. Creatine is synthesized via the S-adenosylmethionine (SAM) dependent methylation of guanidinoacetate (GAA) which is not regulated by a feedback mechanism. The first objective of this study was to determine the effectiveness of GAA at increasing tissue Cr stores. Because SAM is required for other methylation reactions, we also wanted to determine whether an increased creatine synthesis would lead to a lower availability of methyl groups for other methylated products. Three month-old pigs (n = 18) were fed control, GAA- or Cr-supplemented diets twice daily. On day 18 or 19, anesthesia was induced 1–3 hours post feeding and a bolus of [methyl-3H]methionine was intravenously infused. After 30 minutes, the liver was analyzed for methyl-3H incorporation into protein, Cr, phosphatidylcholine (PC) and DNA. Although both Cr and GAA led to higher hepatic Cr concentration, only supplementation with GAA led to higher levels of muscle Cr (P < 0.05). Only GAA supplementation resulted in lower methyl-3H incorporation into PC and protein as well as lower hepatic SAM concentration compared to the controls, suggesting that Cr synthesis resulted in a limited methyl supply for PC and protein synthesis (P < 0.05). Although GAA is more effective than Cr at supporting muscle Cr accretion, further research should be conducted into the long term consequences of a limited methyl supply and its effects on protein and PC homeostasis.
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Affiliation(s)
- Laura E. McBreairty
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Jason L. Robinson
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Kayla R. Furlong
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Janet A. Brunton
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Robert F. Bertolo
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
- * E-mail:
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Almilaji A, Sopjani M, Elvira B, Borras J, Dërmaku-Sopjani M, Munoz C, Warsi J, Lang UE, Lang F. Upregulation of the creatine transporter Slc6A8 by Klotho. Kidney Blood Press Res 2014; 39:516-25. [PMID: 25531216 DOI: 10.1159/000368462] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS The transmembrane Klotho protein contributes to inhibition of 1,25(OH)2D3 formation. The extracellular domain of Klotho protein could function as an enzyme with e.g. β-glucuronidase activity, be cleaved off and be released into blood and cerebrospinal fluid. Klotho regulates several cellular transporters. Klotho protein deficiency accelerates the appearance of age related disorders including neurodegeneration and muscle wasting and eventually leads to premature death. The main site of Klotho protein expression is the kidney. Klotho protein is also appreciably expressed in other tissues including chorioid plexus. The present study explored the effect of Klotho protein on the creatine transporter CreaT (Slc6A8), which participates in the maintenance of neuronal function and survival. METHODS To this end cRNA encoding Slc6A8 was injected into Xenopus oocytes with and without additional injection of cRNA encoding Klotho protein. Creatine transporter CreaT (Slc6A8) activity was estimated from creatine induced current determined by two-electrode voltage-clamp. RESULTS Coexpression of Klotho protein significantly increased creatine-induced current in Slc6A8 expressing Xenopus oocytes. Coexpression of Klotho protein delayed the decline of creatine induced current following inhibition of carrier insertion into the cell membrane by brefeldin A (5 µM). The increase of creatine induced current by coexpression of Klotho protein in Slc6A8 expressing Xenopus oocytes was reversed by β-glucuronidase inhibitor (DSAL). Similarly, treatment of Slc6A8 expressing Xenopus oocytes with recombinant human alpha Klotho protein significantly increased creatine induced current. CONCLUSION Klotho protein up-regulates the activity of creatine transporter CreaT (Slc6A8) by stabilizing the carrier protein in the cell membrane, an effect requiring β-glucuronidase activity of Klotho protein.
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Affiliation(s)
- Ahmad Almilaji
- Department of Physiology, Gmelinstr. 5, University of Tübingen, D-72076 Tübingen, Germany
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van de Kamp JM, Mancini GM, Salomons GS. X-linked creatine transporter deficiency: clinical aspects and pathophysiology. J Inherit Metab Dis 2014; 37:715-33. [PMID: 24789340 DOI: 10.1007/s10545-014-9713-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 12/22/2022]
Abstract
Creatine transporter deficiency was discovered in 2001 as an X-linked cause of intellectual disability characterized by cerebral creatine deficiency. This review describes the current knowledge regarding creatine metabolism, the creatine transporter and the clinical aspects of creatine transporter deficiency. The condition mainly affects the brain while other creatine requiring organs, such as the muscles, are relatively spared. Recent studies have provided strong evidence that creatine synthesis also occurs in the brain, leading to the intriguing question of why cerebral creatine is deficient in creatine transporter deficiency. The possible mechanisms explaining the cerebral creatine deficiency are discussed. The creatine transporter knockout mouse provides a good model to study the disease. Over the past years several treatment options have been explored but no treatment has been proven effective. Understanding the pathogenesis of creatine transporter deficiency is of paramount importance in the development of an effective treatment.
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MESH Headings
- Amino Acid Metabolism, Inborn Errors/diagnosis
- Amino Acid Metabolism, Inborn Errors/drug therapy
- Amino Acid Metabolism, Inborn Errors/genetics
- Amino Acid Metabolism, Inborn Errors/pathology
- Animals
- Brain Diseases, Metabolic, Inborn/complications
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/physiopathology
- Creatine/deficiency
- Creatine/genetics
- Genetic Diseases, X-Linked/genetics
- Humans
- Intellectual Disability/etiology
- Intellectual Disability/genetics
- Membrane Transport Proteins/deficiency
- Membrane Transport Proteins/genetics
- Mental Retardation, X-Linked/complications
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/physiopathology
- Mice
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/genetics
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Affiliation(s)
- Jiddeke M van de Kamp
- Department of Clinical Genetics, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands,
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26
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Brown EL, Snow RJ, Wright CR, Cho Y, Wallace MA, Kralli A, Russell AP. PGC-1α and PGC-1β increase CrT expression and creatine uptake in myotubes via ERRα. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2937-43. [PMID: 25173818 DOI: 10.1016/j.bbamcr.2014.08.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 11/20/2022]
Abstract
Intramuscular creatine plays a crucial role in maintaining skeletal muscle energy homeostasis, and its entry into the cell is dependent upon the sodium chloride dependent Creatine Transporter (CrT; Slc6a8). CrT activity is regulated by a number of factors including extra- and intracellular creatine concentrations, hormones, changes in sodium concentration, and kinase activity, however very little is known about the regulation of CrT gene expression. The present study aimed to investigate how Creatine Transporter (CrT) gene expression is regulated in skeletal muscle. Within the first intron of the CrT gene, we identified a conserved sequence that includes the motif recognized by the Estrogen-related receptor α (ERRα), also known as an Estrogen-related receptor response element (ERRE). Additional ERREs confirming to the known consensus sequence were also identified in the region upstream of the promoter. When partnered with peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PGC-1α) or beta (PGC-1β), ERRα induces the expression of many genes important for cellular bioenergetics. We therefore hypothesized that PGC-1 and ERRα could also regulate CrT gene expression and creatine uptake in skeletal muscle. Here we show that adenoviral overexpression of PGC-1α or PGC-1β in L6 myotubes increased CrT mRNA (2.1 and 1.7-fold, P<0.0125) and creatine uptake (1.8 and 1.6-fold, P<0.0125), and this effect was inhibited with co-expression of shRNA for ERRα. Overexpression of a constitutively active ERRα (VP16-ERRα) increased CrT mRNA approximately 8-fold (P<0.05), resulting in a 2.2-fold (P<0.05) increase in creatine uptake. Lastly, chromatin immunoprecipitation assays revealed that PGC-1α and ERRα directly interact with the CrT gene and increase CrT gene expression.
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Affiliation(s)
- Erin L Brown
- Centre for Physical Activity Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Australia
| | - Rod J Snow
- Centre for Physical Activity Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Australia
| | - Craig R Wright
- Centre for Physical Activity Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Australia
| | - Yoshitake Cho
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Marita A Wallace
- Centre for Physical Activity Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Australia
| | - Anastasia Kralli
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aaron P Russell
- Centre for Physical Activity Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Australia.
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Russell AP, Ghobrial L, Wright CR, Lamon S, Brown EL, Kon M, Skelton MR, Snow RJ. Creatine transporter (SLC6A8) knockout mice display an increased capacity for in vitro creatine biosynthesis in skeletal muscle. Front Physiol 2014; 5:314. [PMID: 25206338 PMCID: PMC4144344 DOI: 10.3389/fphys.2014.00314] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/01/2014] [Indexed: 01/15/2023] Open
Abstract
The present study aimed to investigate whether skeletal muscle from whole body creatine transporter (CrT; SLC6A8) knockout mice (CrT-/y) actually contained creatine (Cr) and if so, whether this Cr could result from an up regulation of muscle Cr biosynthesis. Gastrocnemius muscle from CrT-/y and wild type (CrT+/y) mice were analyzed for ATP, Cr, Cr phosphate (CrP), and total Cr (TCr) content. Muscle protein and gene expression of the enzymes responsible for Cr biosynthesis L-arginine:glycine amidotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT) were also determined as were the rates of in vitro Cr biosynthesis. CrT-/y mice muscle contained measurable (22.3 ± 4.3 mmol.kg−1 dry mass), but markedly reduced (P < 0.05) TCr levels compared with CrT+/y mice (125.0 ± 3.3 mmol.kg−1 dry mass). AGAT gene and protein expression were higher (~3 fold; P < 0.05) in CrT−/y mice muscle, however GAMT gene and protein expression remained unchanged. The in vitro rate of Cr biosynthesis was elevated 1.5 fold (P < 0.05) in CrT−/y mice muscle. These data clearly demonstrate that in the absence of CrT protein, skeletal muscle has reduced, but not absent, levels of Cr. This presence of Cr may be at least partly due to an up regulation of muscle Cr biosynthesis as evidenced by an increased AGAT protein expression and in vitro Cr biosynthesis rates in CrT−/y mice. Of note, the up regulation of Cr biosynthesis in CrT−/y mice muscle was unable to fully restore Cr levels to that found in wild type muscle.
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Affiliation(s)
- Aaron P Russell
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Lobna Ghobrial
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Craig R Wright
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Séverine Lamon
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Erin L Brown
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Michihiro Kon
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
| | - Matthew R Skelton
- Division of Neurology, Department of Pediatrics, Cincinnati Children's Research Foundation, University of Cincinnati College of Medicine Cincinnati, OH, USA
| | - Rodney J Snow
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University VIC, Australia
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Post-transcriptional regulation of the creatine transporter gene: functional relevance of alternative splicing. Biochim Biophys Acta Gen Subj 2014; 1840:2070-9. [PMID: 24561156 DOI: 10.1016/j.bbagen.2014.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 02/07/2014] [Accepted: 02/12/2014] [Indexed: 11/23/2022]
Abstract
BACKGROUND Aberrations in about 10-15% of X-chromosome genes account for intellectual disability (ID); with a prevalence of 1-3% (Gécz et al., 2009 [1]). The SLC6A8 gene, mapped to Xq28, encodes the creatine transporter (CTR1). Mutations in SLC6A8, and the ensuing decrease in brain creatine, lead to co-occurrence of speech/language delay, autism-like behaviors and epilepsy with ID. A splice variant of SLC6A8-SLC6A8C, containing intron 4 and exons 5-13, was identified. Herein, we report the identification of a novel variant - SLC6A8D, and functional relevance of these isoforms. METHODS Via (quantitative) RT-PCR, uptake assays, and confocal microscopy, we investigated their expression and function vis-à-vis creatine transport. RESULTS SLC6A8D is homologous to SLC6A8C except for a deletion of exon 9 (without occurrence of a frame shift). Both contain an open reading frame encoding a truncated protein but otherwise identical to CTR1. Like SLC6A8, both variants are predominantly expressed in tissues with high energy requirement. Our experiments reveal that these truncated isoforms do not transport creatine. However, in SLC6A8 (CTR1)-overexpressing cells, a subsequent infection (transduction) with viral constructs encoding either the SLC6A8C (CTR4) or SLC6A8D (CTR5) isoform resulted in a significant increase in creatine accumulation compared to CTR1 cells re-infected with viral constructs containing the empty vector. Moreover, transient transfection of CTR4 or CTR5 into HEK293 cells resulted in significantly higher creatine uptake. CONCLUSIONS CTR4 and CTR5 are possible regulators of the creatine transporter since their overexpression results in upregulated CTR1 protein and creatine uptake. GENERAL SIGNIFICANCE Provides added insight into the mechanism(s) of creatine transport regulation.
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29
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Zervou S, Ray T, Sahgal N, Sebag-Montefiore L, Cross R, Medway DJ, Ostrowski PJ, Neubauer S, Lygate CA. A role for thioredoxin-interacting protein (Txnip) in cellular creatine homeostasis. Am J Physiol Endocrinol Metab 2013; 305:E263-70. [PMID: 23715727 PMCID: PMC3725544 DOI: 10.1152/ajpendo.00637.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Creatine is important for energy metabolism, yet excitable cells such as cardiomyocytes do not synthesize creatine and rely on uptake via a specific membrane creatine transporter (CrT; SLC6A8). This process is tightly controlled with downregulation of CrT upon continued exposure to high creatine via mechanisms that are poorly understood. Our aim was to identify candidate endogenous CrT inhibitors. In 3T3 cells overexpressing the CrT, creatine uptake plateaued at 3 h in response to 5 mM creatine but peaked 33% higher (P < 0.01) in the presence of cycloheximide, suggesting CrT regulation depends on new protein synthesis. Global gene expression analysis identified thioredoxin-interacting protein (Txnip) as the only significantly upregulated gene (by 46%) under these conditions (P = 0.036), subsequently verified independently at mRNA and protein levels. There was no change in Txnip expression with exposure to 5 mM taurine, confirming a specific response to creatine rather than osmotic stress. Small-interfering RNA against Txnip prevented Txnip upregulation in response to high creatine, maintained normal levels of creatine uptake, and prevented downregulation of CrT mRNA. These findings were relevant to the in vivo heart since creatine-deficient mice showed 39.71% lower levels of Txnip mRNA, whereas mice overexpressing the CrT had 57.6% higher Txnip mRNA levels and 28.7% higher protein expression compared with wild types (mean myocardial creatine concentration 124 and 74 nmol/mg protein, respectively). In conclusion, we have identified Txnip as a novel negative regulator of creatine levels in vitro and in vivo, responsible for mediating substrate feedback inhibition and a potential target for modulating creatine homeostasis.
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Affiliation(s)
- Sevasti Zervou
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Headington, Oxford, United Kingdom.
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30
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Roopchand DE, Kuhn P, Rojo LE, Lila MA, Raskin I. Blueberry polyphenol-enriched soybean flour reduces hyperglycemia, body weight gain and serum cholesterol in mice. Pharmacol Res 2013; 68:59-67. [PMID: 23220243 PMCID: PMC3833590 DOI: 10.1016/j.phrs.2012.11.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 10/27/2022]
Abstract
Defatted soybean flour (DSF) can sorb and concentrate blueberry anthocyanins and other polyphenols, but not sugars. In this study blueberry polyphenol-enriched DSF (BB-DSF) or DSF were incorporated into very high fat diet (VHFD) formulations and provided ad libitum to obese and hyperglycemic C57BL/6 mice for 13 weeks to investigate anti-diabetic effects. Compared to the VHFD containing DSF, the diet supplemented with BB-DSF reduced weight gain by 5.6%, improved glucose tolerance, and lowered fasting blood glucose levels in mice within 7 weeks of intervention. Serum cholesterol of mice consuming the BB-DSF-supplemented diet was 13.2% lower than mice on the diet containing DSF. Compounds were eluted from DSF and BB-DSF for in vitro assays of glucose production and uptake. Compared to untreated control, doses of BB-DSF eluate containing 0.05-10μg/μL of blueberry anthocyanins significantly reduced glucose production by 24-74% in H4IIE rat hepatocytes, but did not increase glucose uptake in L6 myotubes. The results indicate that delivery of blueberry polyphenols stabilized in a high-protein food matrix may be useful for the dietary management of pre-diabetes and/or diabetes.
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Affiliation(s)
- Diana E. Roopchand
- Rutgers, The State University of New Jersey, School of Environmental and Biological Sciences, Foran Hall, 59 Dudley Road, New Brunswick, NJ 08901, USA
| | - Peter Kuhn
- Rutgers, The State University of New Jersey, School of Environmental and Biological Sciences, Foran Hall, 59 Dudley Road, New Brunswick, NJ 08901, USA
| | - Leonel E. Rojo
- Rutgers, The State University of New Jersey, School of Environmental and Biological Sciences, Foran Hall, 59 Dudley Road, New Brunswick, NJ 08901, USA
| | - Mary Ann Lila
- Plants for Human Health Institute, North Carolina State University, 600 Laureate Way, Kannapolis, NC 28081, USA
| | - Ilya Raskin
- Rutgers, The State University of New Jersey, School of Environmental and Biological Sciences, Foran Hall, 59 Dudley Road, New Brunswick, NJ 08901, USA
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31
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Darrabie MD, Arciniegas AJL, Mantilla JG, Mishra R, Vera MP, Santacruz L, Jacobs DO. Exposing cardiomyocytes to subclinical concentrations of doxorubicin rapidly reduces their creatine transport. Am J Physiol Heart Circ Physiol 2012; 303:H539-48. [PMID: 22752631 DOI: 10.1152/ajpheart.00108.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Doxorubicin is commonly used to treat leukemia, lymphomas, and solid tumors, such as soft tissue sarcomas or breast cancer. A major side effect of doxorubicin therapy is dose-dependent cardiotoxicity. Doxorubicin's effects on cardiac energy metabolism are emerging as key elements mediating its toxicity. We evaluated the effect of doxorubicin on [(14)C]creatine uptake in rat neonatal cardiac myocytes and HL-1 murine cardiac cells expressing the human creatine transporter protein. A significant and irreversible decrease in creatine transport was detected after an incubation with 50-100 nmol/l doxorubicin. These concentrations are well below peak plasma levels (5 μmol/l) and within the ranges (25-250 nmol/l) for steady-state plasma concentrations reported after the administration of 15-90 mg/m(2) doxorubicin for chemotherapy. The decrease in creatine transport was not solely because of increased cell death due to doxorubicin's cytotoxic effects. Kinetic analysis showed that doxorubicin decreased V(max), K(m), and creatine transporter protein content. Cell surface biotinylation experiments confirmed that the amount of creatine transporter protein present at the cell surface was reduced. Cardiomyocytes rely on uptake by a dedicated creatine transporter to meet their intracellular creatine needs. Our findings show that the cardiomyocellular transport capacity for creatine is substantially decreased by doxorubicin administration and suggest that this effect may be an important early event in the pathogenesis of doxorubicin-mediated cardiotoxicity.
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Affiliation(s)
- Marcus D Darrabie
- Surgery Department, Duke University Medical Center, Durham, North Carolina 27710, USA
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32
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Downregulation of the Creatine Transporter SLC6A8 by JAK2. J Membr Biol 2012; 245:157-63. [DOI: 10.1007/s00232-012-9424-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 02/16/2012] [Indexed: 12/20/2022]
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Rojo LE, Ribnicky D, Logendra S, Poulev A, Rojas-Silva P, Kuhn P, Dorn R, Grace MH, Lila MA, Raskin I. In Vitro and in Vivo Anti-Diabetic Effects of Anthocyanins from Maqui Berry ( Aristotelia chilensis). Food Chem 2012; 131:387-396. [PMID: 26279603 DOI: 10.1016/j.foodchem.2011.08.066] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We used a murine model of type II diabetes, which reproduces the major features of the human disease, and a number of cellular models to study the antidiabetic effect of ANC, a standardised anthocyanin-rich formulation from maqui berry (Aristotelia chilensis). We also isolated delphinidin 3-sambubioside-5-glucoside (D3S5G), a characteristic anthocyanin from maqui berry, and studied its antidiabetic properties. We observed that oral administration of ANC improved fasting blood glucose levels and glucose tolerance in hyperglycaemic obese C57BL/6J mice fed a high fat diet. In H4IIE rat liver cells, ANC decreased glucose production and enhanced the insulin-stimulated down regulation of the gluconeogenic enzyme, glucose-6-phosphatase. In L6 myotubes ANC treatment increased both insulin and non-insulin mediated glucose uptake. As with the ACN, oral administration of pure D3S5G dose-dependently decreased fasting blood glucose levels in obese C57BL/6J mice, and decreased glucose production in rat liver cells. D3S5G also increased glucose uptake in L6 myotubes and is at least partially responsible for ANC's anti-diabetic properties.
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Affiliation(s)
| | | | | | - Alex Poulev
- Rutgers University, SEBS, New Brunswick, NJ 08901
| | | | - Peter Kuhn
- Rutgers University, SEBS, New Brunswick, NJ 08901
| | - Ruth Dorn
- Rutgers University, SEBS, New Brunswick, NJ 08901
| | - Mary H Grace
- North Carolina State University, Kannapolis, NC, USA
| | - Mary Ann Lila
- North Carolina State University, Kannapolis, NC, USA
| | - Ilya Raskin
- Rutgers University, SEBS, New Brunswick, NJ 08901
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Darrabie MD, Arciniegas AJL, Mishra R, Bowles DE, Jacobs DO, Santacruz L. AMPK and substrate availability regulate creatine transport in cultured cardiomyocytes. Am J Physiol Endocrinol Metab 2011; 300:E870-6. [PMID: 21364119 DOI: 10.1152/ajpendo.00554.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Profound alterations in myocellular creatine and phosphocreatine levels are observed during human heart failure. To maintain its intracellular creatine stores, cardiomyocytes depend upon a cell membrane creatine transporter whose regulation is not clearly understood. Creatine transport capacity in the intact heart is modulated by substrate availability, and it is reduced in the failing myocardium, likely adding to the energy imbalance that characterizes heart failure. AMPK, a key regulator of cellular energy homeostasis, acts by switching off energy-consuming pathways in favor of processes that generate energy. Our objective was to determine the effects of substrate availability and AMPK activation on creatine transport in cardiomyocytes. We studied creatine transport in rat neonatal cardiomyocytes and HL-1 cardiac cells expressing the human creatine transporter cultured in the presence of varying creatine concentrations and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR). Transport was enhanced in cardiomyocytes following incubation in creatine-depleted medium or AICAR. The changes in transport were due to alterations in V(max) that correlated with changes in total and cell surface creatine transporter protein content. Our results suggest a positive role for AMPK in creatine transport modulation for cardiomyocytes in culture.
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Affiliation(s)
- Marcus D Darrabie
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA
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35
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Valayannopoulos V, Boddaert N, Mention K, Touati G, Barbier V, Chabli A, Sedel F, Kaplan J, Dufier JL, Seidenwurm D, Rabier D, Saudubray JM, de Lonlay P. Secondary creatine deficiency in ornithine delta-aminotransferase deficiency. Mol Genet Metab 2009; 97:109-13. [PMID: 19345633 DOI: 10.1016/j.ymgme.2008.12.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Revised: 12/05/2008] [Accepted: 12/05/2008] [Indexed: 11/28/2022]
Abstract
AIMS Ornithine delta-aminotransferase (OAT) deficiency causes gyrate atrophy (GA) of the retina, as a consequence of high plasma ornithine concentrations. Because creatine synthesis requires the conversion of arginine and glycine into ornithine and guanidinoacetate, high ornithine concentration inhibits this reaction thus causing secondary creatine deficiency. The aim of this study was to evaluate the neuropsychological features and creatine metabolism in patients with GA. METHODS The study involved 7 GA patients, aged from 11 to 27 years who underwent neuropsychological evaluation and cerebral proton magnetic resonance spectroscopy (MRS). RESULTS Neurocognitive impairment was found in 5/7 patients, including mental retardation (3/7), school failure (1/7), major visuospatial dyspraxia (1/7), aggressive behavior (3/7) and epilepsy (2/7). Two patients had normal neuropsychological evaluation. Cerebral proton magnetic resonance spectroscopy revealed a profound creatine deficiency in all patients. MRS data were confirmed by decreased levels of creatine and/or guanidinoacetate in plasma and urine in all patients. CONCLUSIONS In our group of patients with GA, we found a high prevalence of neurological impairment, not reported so far, and possibly related to secondary creatine deficiency and hyperornithinemia. We propose to treat mentally retarded GA patients with high doses of creatine, as it may normalize brain creatine levels and help to reduce ornithine levels.
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Affiliation(s)
- V Valayannopoulos
- Reference Center for Metabolic Disorders, Necker - Enfants Malades Hospital and Université Paris Descartes, 149 rue de Sèvres, 75015 Paris, France.
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Spillane M, Schoch R, Cooke M, Harvey T, Greenwood M, Kreider R, Willoughby DS. The effects of creatine ethyl ester supplementation combined with heavy resistance training on body composition, muscle performance, and serum and muscle creatine levels. J Int Soc Sports Nutr 2009; 6:6. [PMID: 19228401 PMCID: PMC2649889 DOI: 10.1186/1550-2783-6-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 02/19/2009] [Indexed: 12/11/2022] Open
Abstract
Numerous creatine formulations have been developed primarily to maximize creatine absorption. Creatine ethyl ester is alleged to increase creatine bio-availability. This study examined how a seven-week supplementation regimen combined with resistance training affected body composition, muscle mass, muscle strength and power, serum and muscle creatine levels, and serum creatinine levels in 30 non-resistance-trained males. In a double-blind manner, participants were randomly assigned to a maltodextrose placebo (PLA), creatine monohydrate (CRT), or creatine ethyl ester (CEE) group. The supplements were orally ingested at a dose of 0.30 g/kg fat-free body mass (approximately 20 g/day) for five days followed by ingestion at 0.075 g/kg fat free mass (approximately 5 g/day) for 42 days. Results showed significantly higher serum creatine concentrations in PLA (p = 0.007) and CRT (p = 0.005) compared to CEE. Serum creatinine was greater in CEE compared to the PLA (p = 0.001) and CRT (p = 0.001) and increased at days 6, 27, and 48. Total muscle creatine content was significantly higher in CRT (p = 0.026) and CEE (p = 0.041) compared to PLA, with no differences between CRT and CEE. Significant changes over time were observed for body composition, body water, muscle strength and power variables, but no significant differences were observed between groups. In conclusion, when compared to creatine monohydrate, creatine ethyl ester was not as effective at increasing serum and muscle creatine levels or in improving body composition, muscle mass, strength, and power. Therefore, the improvements in these variables can most likely be attributed to the training protocol itself, rather than the supplementation regimen.
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Affiliation(s)
- Mike Spillane
- Department of Health, Human Performance and Recreation, Baylor University, Box 97313, Waco, TX 76798, USA.
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37
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Creatine uptake in mouse hearts with genetically altered creatine levels. J Mol Cell Cardiol 2008; 45:453-9. [PMID: 18602925 PMCID: PMC2568826 DOI: 10.1016/j.yjmcc.2008.05.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 05/22/2008] [Accepted: 05/30/2008] [Indexed: 11/24/2022]
Abstract
Creatine plays an important role in energy metabolism in the heart. Cardiomyocytes accumulate creatine via a specific creatine transporter (CrT), the capacity of which is reduced in the failing heart, resulting in lower myocardial creatine concentration. Therefore, to gain insight into how the CrT is regulated, we studied two mouse models of severely altered myocardial creatine levels. Cardiac creatine uptake levels were measured in isolated hearts from creatine-free guanidinoacetate-N-methyl transferase knock out (GAMT−/−) mice and from mice overexpressing the myocardial CrT (CrT-OE) using 14C-radiolabeled creatine. CrT mRNA levels were measured using real time RT-PCR and creatine levels with HPLC. Hearts from GAMT−/− mice showed a 7-fold increase in Vmax of creatine uptake and a 1.4-fold increase in CrT mRNA levels. The increase in Cr uptake and in CrT mRNA levels, however, was almost completely prevented when mice were fed a creatine supplemented diet, indicating that creatine uptake is subject to negative feedback regulation. Cardiac creatine uptake levels in CrT-OE mice were increased on average 2.7-fold, showing a considerable variation, in line with a similar variation in creatine content. Total CrT mRNA levels correlated well with myocardial creatine content (r = 0.67; p < 0.0001) but endogenous CrT mRNA levels did not correlate at all with myocardial creatine content (r = 0.01; p = 0.96). This study shows that creatine uptake can be massively upregulated in the heart, by almost an order of magnitude and that this upregulation is subject to feedback inhibition. In addition, our results strongly suggest that CrT activity is predominantly regulated by mechanisms other than alterations in gene expression.
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Abstract
Physical training and proper nutrition are paramount for success in sport. A key tissue is skeletal muscle, as the metabolic pathways that produce energy or ATP allow the muscles to complete the many activities critical to success in sport. The energy-producing pathways must rapidly respond to the need for ATP during sport and produce energy at a faster rate or for a longer duration through training and proper nutrition which should translate into improved performance in sport activities. There is also continual interest in the possibility that nutritional supplements could further improve muscle metabolism and the provision of energy during sport. Most legal sports supplements do not improve performance following oral ingestion. However, three legal supplements that have received significant attention over the years include creatine, carnitine and sodium bicarbonate. The ingestion of large amounts of creatine for 4–6 days increases skeletal muscle creatine and phosphocreatine contents. The majority of the experimental evidence suggests that creatine supplementation can improve short-term exercise performance, especially in sports that require repeated short-term sprints. It may also augment the accretion of skeletal muscle when taken in combination with a resistance-exercise training programme. Supplementary carnitine has been touted to increase the uptake and oxidation of fat in the mitochondria. However, muscle carnitine levels are not augmented following oral carnitine supplementation and the majority of well-controlled studies have reported no effect of carnitine on enhancing fat oxidation, V̇o2max or prolonged endurance exercise performance. The ingestion of sodium bicarbonate before intense exercise decreases the blood [H+] to potentially assist the efflux of H+ from the muscle and temper the metabolic acidosis associated with intense exercise. Many studies have reported performance increases in laboratory-based cycling tests and simulated running races in the field following sodium bicarbonate ingestion where the need for ATP from substrate phosphorylation is high. However, other studies have reported no benefit and the incidence of negative side effects is high.
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Abstract
Significant progress has been made in identifying neuroprotective agents and their translation to patients with neurological disorders. While the direct causative pathways of neurodegeneration remain unclear, they are under great clinical and experimental investigation. There are a number of interrelated pathogenic mechanisms triggering molecular events that lead to neuronal death. One putative mechanism reported to play a prominent role in the pathogenesis of neurological diseases is impaired energy metabolism. If reduced energy stores play a role in neuronal loss, then therapeutic strategies that buffer intracellular energy levels may prevent or impede the neurodegenerative process. Recent studies suggest that impaired energy production promotes neurological disease onset and progression. Sustained ATP levels are critical to cellular homeostasis and may have both direct and indirect influence on pathogenic mechanisms associated with neurological disorders. Creatine is a critical component in maintaining cellular energy homeostasis, and its administration has been reported to be neuroprotective in a wide number of both acute and chronic experimental models of neurological disease. In the context of this chapter, we will review the experimental evidence for creatine supplementation as a neurotherapeutic strategy in patients with neurological disorders, including Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease, as well as in ischemic stroke, brain and spinal cord trauma, and epilepsy.
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Wyss M, Braissant O, Pischel I, Salomons GS, Schulze A, Stockler S, Wallimann T. Creatine and creatine kinase in health and disease--a bright future ahead? Subcell Biochem 2007; 46:309-34. [PMID: 18652084 DOI: 10.1007/978-1-4020-6486-9_16] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many links are reported or suspected between the functioning of creatine, phosphocreatine, the creatine kinase isoenzymes or the creatine biosynthesis enzymes on one hand, and health or disease on the other hand. The aim of the present book was to outline our current understanding on many of these links. In this chapter, we summarize the main messages and conclusions presented in this book. In addition, we refer to a number of recent publications that highlight the pleiotropy in physiological functions of creatine and creatine kinase, and which suggest that numerous discoveries on new functions of this system are still ahead of us. Finally, we present our views on the most promising future avenues of research to deepen our knowledge on creatine and creatine kinase. In particular, we elaborate on how state-of-the-art high-throughput analytical ("omics") technologies and systems biology approaches may be used successfully to unravel the complex network of interdependent physiological functions related to creatine and creatine kinase.
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Affiliation(s)
- Markus Wyss
- DSM Nutritional Products Ltd., Biotechnology R&D, Bldg. 203/17B, P.O. Box 3255, CH-4002 Basel, Switzerland
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Abstract
Creatine and phosphocreatine provide an intracellular, high-energy phosphate buffering system, essential to maintain ATP levels in tissues with high energy demands. A specific plasma membrane creatine transporter (CRT) is required for the cellular uptake of creatine. This transporter is related to the gamma-aminobutyric acid (GAT) and norepinephrine (NET) transporters and is part of a large gene family of Na(+) - and Cl(-) -dependent neurotransmitter transporters, now known as solute carrier family 6 (SLC6). CRT is essential for normal brain function as mutations in the CRT gene (SLC6A8) result in X-linked mental retardation, associated with the almost complete lack of creatine in the brain, severe speech and language delay, epilepsy, and autistic behaviour. Insight into the structure and function of the CRT has come from studies of creatine transport by tissues and cells, in vitro studies of CRT mutations, identification of mutations associated with CRT deficiency, and from the recent high resolution structure of a prokaryotic homologue of the SLC6 transporters. CRT antibodies have been developed enabling the localization of creatine uptake sites in the brain, retina, muscle and other tissues. These tools in conjunction with the use of appropriate cell models should allow further progress in our knowledge on the regulation and cellular trafficking of the CRT. Development of suitable mouse models may allow improved understanding of the importance of the CRT for normal brain function and how the transporter is regulated in vivo.
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Affiliation(s)
- David L Christie
- Molecular, Cell and Developmental Biology Section, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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Abstract
Creatine and phosphocreatine serve not only as an intracellular buffer for adenosine triphosphate, but also as an energy shuttle for the movement of high-energy phosphates from mitochondrial sites of production to cytoplasmic sites of utilization. The spontaneous loss of creatine and of phosphocreatine to creatinine requires that creatine be continuously replaced; this occurs by a combination of diet and endogenous synthesis. Vegetarians obtain almost no dietary creatine. Creatine synthesis makes major demands on the metabolism of glycine, arginine, and methionine. Large doses of creatine monohydrate are widely taken, particularly by athletes, as an ergogenic supplement; creatine supplements are also taken by patients suffering from gyrate atrophy, muscular dystrophy, and neurodegenerative diseases. Children with inborn errors of creatine synthesis or transport present with severe neurological symptoms and a profound depletion of brain creatine. It is evident that creatine plays a critical, though underappreciated, role in brain function.
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Affiliation(s)
- John T Brosnan
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
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Kan HE, Meeuwissen E, van Asten JJ, Veltien A, Isbrandt D, Heerschap A. Creatine uptake in brain and skeletal muscle of mice lacking guanidinoacetate methyltransferase assessed by magnetic resonance spectroscopy. J Appl Physiol (1985) 2007; 102:2121-7. [PMID: 17347380 DOI: 10.1152/japplphysiol.01327.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Creatine (Cr) levels in skeletal muscle and brain of a mouse model of Cr deficiency caused by guanidinoacetate methyltransferase absence (GAMT-/-) were studied after Cr supplementation with 2 g.kg body wt-1.day-1 Cr for 35 days. Localized 1H magnetic resonance spectroscopy (MRS) was performed in brain (cerebellum and thalamus/hippocampus) and in hind leg muscle of GAMT-/- mice before and after Cr supplementation and in control (Con) mice. As expected, a signal for Cr was hardly detectable in MR spectra of GAMT-/- mice before Cr supplementation. In the thalamus/hippocampus region of these mice, an increase in N-acetylasparate (NAA) was observed. During Cr administration, Cr levels increased faster in skeletal muscle compared with brain, but this occurred only during the first day of supplementation. Thereafter, Cr levels increased by 0.8 mM/day in all studied locations. After 35 days of Cr supplementation, Cr levels in all locations were higher compared with Con mice on a Cr-free diet and NAA levels normalized. Only because of the repeated MRS measurements performed in this longitudinal Cr supplementation study on GAMT-/- mice were we able to discover the initial faster uptake of Cr in skeletal muscle compared with brain, which may represent muscular Cr uptake independent of Cr transporter expression. Our results can provide the basis for additional experiments to optimize Cr supplementation in GAMT deficiency, as increases in brain Cr are slow in patients after Cr supplementation.
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Affiliation(s)
- Hermien E Kan
- Department of Radiology, Radboud University Nijmegen Medical Center, Geert Grooteplein 10, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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Stockler S, Schutz PW, Salomons GS. Cerebral creatine deficiency syndromes: clinical aspects, treatment and pathophysiology. Subcell Biochem 2007; 46:149-166. [PMID: 18652076 DOI: 10.1007/978-1-4020-6486-9_8] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cerebral creatine deficiency syndromes (CCDSs) are a group of inborn errors of creatine metabolism comprising two autosomal recessive disorders that affect the biosynthesis of creatine--i.e. arginine:glycine amidinotransferase deficiency (AGAT; MIM 602360) and guanidinoacetate methyltransferase deficiency (GAMT; MIM 601240)--and an X-linked defect that affects the creatine transporter, SLC6A8 deficiency (SLC6A8; MIM 300036). The biochemical hallmarks of these disorders include cerebral creatine deficiency as detected in vivo by 1H magnetic resonance spectroscopy (MRS) of the brain, and specific disturbances in metabolites of creatine metabolism in body fluids. In urine and plasma, abnormal guanidinoacetic acid (GAA) levels are found in AGAT deficiency (reduced GAA) and in GAMT deficiency (increased GAA). In urine of males with SLC6A8 deficiency, an increased creatine/creatinine ratio is detected. The common clinical presentation in CCDS includes mental retardation, expressive speech and language delay, autistic like behaviour and epilepsy. Treatment of the creatine biosynthesis defects has yielded clinical improvement, while for creatine transporter deficiency, successful treatment strategies still need to be discovered. CCDSs may be responsible for a considerable fraction of children and adults affected with mental retardation of unknown etiology. Thus, screening for this group of disorders should be included in the differential diagnosis of this population. In this review, also the importance of CCDSs for the unravelling of the (patho)physiology of cerebral creatine metabolism is discussed.
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MESH Headings
- Adult
- Amidinotransferases/deficiency
- Animals
- Brain Diseases, Metabolic, Inborn/diagnosis
- Brain Diseases, Metabolic, Inborn/enzymology
- Brain Diseases, Metabolic, Inborn/pathology
- Brain Diseases, Metabolic, Inborn/physiopathology
- Brain Diseases, Metabolic, Inborn/therapy
- Cerebellar Diseases/diagnosis
- Cerebellar Diseases/enzymology
- Cerebellar Diseases/pathology
- Cerebellar Diseases/physiopathology
- Cerebellar Diseases/therapy
- Child
- Child, Preschool
- Creatine/deficiency
- Creatine/metabolism
- Creatinine/metabolism
- Diagnosis, Differential
- Female
- Genetic Diseases, X-Linked/diagnosis
- Genetic Diseases, X-Linked/enzymology
- Genetic Diseases, X-Linked/pathology
- Genetic Diseases, X-Linked/physiopathology
- Genetic Diseases, X-Linked/therapy
- Glycine/analogs & derivatives
- Glycine/metabolism
- Guanidinoacetate N-Methyltransferase/deficiency
- Humans
- Male
- Nerve Tissue Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Syndrome
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Affiliation(s)
- Sylvia Stockler
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, B.C., V6H 3V4, Canada
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45
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Derave W, Straumann N, Olek RA, Hespel P. Electrolysis stimulates creatine transport and transporter cell surface expression in incubated mouse skeletal muscle: potential role of ROS. Am J Physiol Endocrinol Metab 2006; 291:E1250-7. [PMID: 16849631 DOI: 10.1152/ajpendo.00060.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Electrical field stimulation of isolated, incubated rodent skeletal muscles is a frequently used model to study the effects of contractions on muscle metabolism. In this study, this model was used to investigate the effects of electrically stimulated contractions on creatine transport. Soleus and extensor digitorum longus muscles of male NMRI mice (35-50 g) were incubated in an oxygenated Krebs buffer between platinum electrodes. Muscles were exposed to [(14)C]creatine for 30 min after either 12 min of repeated tetanic isometric contractions (contractions) or electrical stimulation of only the buffer before incubation of the muscle (electrolysis). Electrolysis was also investigated in the presence of the reactive oxygen species (ROS) scavenging enzymes superoxide dismutase (SOD) and catalase. Both contractions and (to a lesser degree) electrolysis stimulated creatine transport severalfold over basal. The amount of electrolysis, but not contractile activity, induced (determined) creatine transport stimulation. Incubation with SOD and catalase at 100 and 200 U/ml decreased electrolysis-induced creatine transport by approximately 50 and approximately 100%, respectively. The electrolysis effects on creatine uptake were completely inhibited by beta-guanidino propionic acid, a competitive inhibitor of (creatine for) the creatine transporter (CRT), and were accompanied by increased cell surface expression of CRT. Muscle glucose transport was not affected by electrolysis. The present results indicate that electrical field stimulation of incubated mouse muscles, independently of contractions per se, stimulates creatine transport by a mechanism that depends on electrolysis-induced formation of ROS in the incubation buffer. The increased creatine uptake is paralleled by an increased cell surface expression of the creatine transporter.
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Affiliation(s)
- Wim Derave
- Dept. of Biomedical Kinesiology, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium
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46
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Cullen ME, Yuen AHY, Felkin LE, Smolenski RT, Hall JL, Grindle S, Miller LW, Birks EJ, Yacoub MH, Barton PJR. Myocardial expression of the arginine:glycine amidinotransferase gene is elevated in heart failure and normalized after recovery: potential implications for local creatine synthesis. Circulation 2006; 114:I16-20. [PMID: 16820567 DOI: 10.1161/circulationaha.105.000448] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Combination therapy consisting of mechanical unloading using a left ventricular assist device (LVAD) and pharmacological intervention can promote recovery from end-stage heart failure, but the mechanism is unknown. Preliminary microarray analysis revealed a significant and unexpected decrease in myocardial arginine:glycine amidinotransferase (AGAT) gene expression during recovery in these patients. The aim of this study was to evaluate the expression and role of AGAT expression in heart failure and recovery. METHODS AND RESULTS We used quantitative real time (TaqMan) polymerase chain reaction to examine myocardial AGAT mRNA expression in implant and explant samples from recovering patients after combination therapy (n=12), end-stage heart failure (ESHF) samples from stable patients undergoing transplantation without LVAD support (n=10), and donor hearts with normal hemodynamic function (n=8). AGAT mRNA expression was significantly elevated in all heart failure patients relative to donors (4.3-fold [P<0.001] and 2.7-fold [P<0.005] in LVAD and ESHF relative to donors, respectively) and returned to normal levels after recovery. AGAT enzyme activity was detectable in both human and rat myocardia and was elevated in heart failure. CONCLUSIONS Our data highlight local and potentially regulated expression of AGAT activity in the myocardium and suggest a specific response to heart failure involving elevated local creatine synthesis. These findings have implications both for the management of recovery patients undergoing combination therapy and for heart failure in general.
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Affiliation(s)
- Martin E Cullen
- National Heart and Lung Institute, Imperial College London, Heart Science Centre, Harefield, Middlesex, UB9 6JH, UK
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Shojaiefard M, Christie DL, Lang F. Stimulation of the creatine transporter SLC6A8 by the protein kinases SGK1 and SGK3. Biochem Biophys Res Commun 2006; 334:742-6. [PMID: 16036218 DOI: 10.1016/j.bbrc.2005.06.164] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 06/24/2005] [Indexed: 11/19/2022]
Abstract
Creatine binds phosphate thus serving energy storage. Cellular creatine uptake is accomplished by the Na+,Cl-, creatine transporter CreaT (SLC6A8). The present study explored the regulation of SLC6A8 by the serum and glucocorticoid inducible kinase SGK1, a kinase upregulated during ischemia. In Xenopus oocytes expressing SLC6A8 but not in water injected oocytes creatine induced a current which was significantly enhanced by coexpression of wild type SGK1 and constitutively active (S422D)SGK1, but not inactive (K127N)SGK1. Kinetic analysis revealed that (S422D)SGK1 enhanced maximal current without significantly altering affinity. The effect of SGK1 was mimicked by the constitutively active isoform (S419D)SGK3 but not by inactive (K119N)SGK3, wild type isoform SGK2 or constitutively active related kinase (T308D,S473D)PKB. In conclusion, the kinases SGK1 and SGK3 increase SLC6A8 activity by increasing the maximal transport rate of the carrier. Deranged SGK1 and/or SGK3 dependent regulation of SLC6A8 may affect energy storage particularly in skeletal muscle, heart, and neurons.
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Gallo M, Gordon T, Syrotuik D, Shu Y, Tyreman N, MacLean I, Kenwell Z, Putman CT. Effects of long-term creatine feeding and running on isometric functional measures and myosin heavy chain content of rat skeletal muscles. Pflugers Arch 2006; 452:744-55. [PMID: 16688465 DOI: 10.1007/s00424-006-0079-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 12/07/2005] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
The purpose of this study was to investigate whether creatine (Cr) supplementation during 12 weeks of phasic high-frequency voluntary wheel running would result in a faster myosin heavy chain (MHC) isoform profile in the rat mixed fast-twitch plantaris and alter its corresponding isometric contractile properties. The fast-twitch extensor digitorum longus and medial gastrocnemius and slow-twitch soleus were also studied. Forty weanling Sprague-Dawley male rats were assigned to one of four groups: creatine-sedentary (Cre-Sed); creatine-voluntary running (Cre-Run); control-sedentary (Con-Sed); control-voluntary running (Con-Run). Daily running distance was similar between Cre-Run and Con-Run. Average daily Cr ingestion was also similar being 2.4+/-0.17 and 3.0+/-0.14 g/kg in Cre-Sed and Cre-Run, respectively. Total creatine (TCr) content was elevated (P<0.03) in the plantaris of Cre-Run [211.4+/-16.9 mmol/kg dry weight (dw)], compared with Con-Run (175.1+/-5.69). In the plantaris, MHCIIb was 13% greater (P<0.00001) in Cre-Run compared with Con-Run, while MHCIId/x and MHCIIa were lower in Cre-Run by 7 and 6% (P<0.0002), respectively. No differences were observed in twitch force, time-to-peak tension, half-rise time or half-fall time. Greater tetanic force production (P<0.05) in Cre-Sed compared with Con-Sed corresponded to a 12% increase in MHCIId/x (P<0.0001) and a 12% decrease in MHCIIb (P<0.0006). The fatigue index of the plantaris at 10 s (FI(10s)) was reduced only after running (Cre-Run vs Con-Run), while in all other muscles the FI(10s) was lower only in the Cre-Sed group. In conclusion, Cr supplementation had differential effects on MHC isoform content and fatigability that depended on the level of contractile activity. Cr feeding combined with running exercise resulted in a faster MHC-based phenotype in the rat plantaris but the impact on associated isometric contractile properties was minimal.
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Affiliation(s)
- Maria Gallo
- Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, University of Alberta, Edmonton T6G 2H9, Alberta, Canada
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Wallis J, Lygate CA, Fischer A, ten Hove M, Schneider JE, Sebag-Montefiore L, Dawson D, Hulbert K, Zhang W, Zhang MH, Watkins H, Clarke K, Neubauer S. Supranormal myocardial creatine and phosphocreatine concentrations lead to cardiac hypertrophy and heart failure: insights from creatine transporter-overexpressing transgenic mice. Circulation 2006; 112:3131-9. [PMID: 16286605 DOI: 10.1161/circulationaha.105.572990] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heart failure is associated with deranged cardiac energy metabolism, including reductions of creatine and phosphocreatine. Interventions that increase myocardial high-energy phosphate stores have been proposed as a strategy for treatment of heart failure. Previously, it has not been possible to increase myocardial creatine and phosphocreatine concentrations to supranormal levels because they are subject to tight regulation by the sarcolemmal creatine transporter (CrT). METHODS AND RESULTS We therefore created 2 transgenic mouse lines overexpressing the myocardial creatine transporter (CrT-OE). Compared with wild-type (WT) littermate controls, total creatine (by high-performance liquid chromatography) was increased in CrT-OE hearts (66+/-6 nmol/mg protein in WT versus 133+/-52 nmol/mg protein in CrT-OE). Phosphocreatine levels (by 31P magnetic resonance spectroscopy) were also increased but to a lesser extent. Surprisingly, CrT-OE mice developed left ventricular (LV) dilatation (LV end-diastolic volume: 21.5+/-4.3 microL in WT versus 33.1+/-9.6 microL in CrT-OE; P=0.002), substantial LV dysfunction (ejection fraction: 64+/-9% in WT versus 49+/-13% in CrT-OE; range, 22% to 70%; P=0.003), and LV hypertrophy (by 3-dimensional echocardiography and magnetic resonance imaging). Myocardial creatine content correlated closely with LV end-diastolic volume (r=0.51, P=0.02), ejection fraction (r=-0.74, P=0.0002), LV weight (r=0.59, P=0.006), LV end-diastolic pressure (r=0.52, P=0.02), and dP/dt(max) (r=-0.69, P=0.0008). Despite increased creatine and phosphocreatine levels, CrT-OE hearts showed energetic impairment, with increased free ADP concentrations and reduced free-energy change levels. CONCLUSIONS Overexpression of the CrT leads to supranormal levels of myocardial creatine and phosphocreatine, but the heart is incapable of keeping the augmented creatine pool adequately phosphorylated, resulting in increased free ADP levels, LV hypertrophy, and dysfunction. Our data demonstrate that a disturbance of the CrT-mediated tight regulation of cardiac energy metabolism has deleterious functional consequences. These findings caution against the uncritical use of creatine as a therapeutic agent in heart disease.
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Affiliation(s)
- Julie Wallis
- Department of Cardiovascular Medicine, University of Oxford, Oxford, England
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Ryu H, Rosas HD, Hersch SM, Ferrante RJ. The therapeutic role of creatine in Huntington's disease. Pharmacol Ther 2005; 108:193-207. [PMID: 16055197 DOI: 10.1016/j.pharmthera.2005.04.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Accepted: 04/07/2005] [Indexed: 12/12/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant and fatal neurological disorder characterized by a clinical triad of progressive choreiform movements, psychiatric symptoms, and cognitive decline. HD is caused by an expanded trinucleotide CAG repeat in the gene coding for the protein huntingtin. No proven treatment to prevent the onset or to delay the progression of HD currently exists. While a direct causative pathway from the gene mutation to the selective neostriatal neurodegeneration remains unclear, it has been hypothesized that interactions of the mutant huntingtin protein or its fragments may result in a number of interrelated pathogenic mechanisms triggering a cascade of molecular events that lead to the untimely neuronal death observed in HD. One putative pathological mechanism reported to play a prominent role in the pathogenesis of HD is mitochondrial dysfunction and the subsequent reduction of cellular energy. Indeed, if mitochondrial impairment and reduced energy stores play roles in the neuronal loss in HD, then a therapeutic strategy that buffers intracellular energy levels may ameliorate the neurodegenerative process. Sustained ATP levels may have both direct and indirect importance in ameliorating the severity of many of the pathogenic mechanisms associated with HD. Creatine, a guanidino compound produced endogenously and acquired exogenously through diet, is a critical component in maintaining much needed cellular energy. As such, creatine is one of a number of ergogens that may provide a relatively safe and immediately available therapeutic strategy to HD patients that may be the cornerstone of a combined treatment necessary to delay the relentless progression of HD.
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Affiliation(s)
- Hoon Ryu
- Experimental Neuropathology Unit and Translational Therapeutics Laboratory, Geriatric Research Education Clinical Center, Bedford VA Medical Center, MA 01730, USA
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