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Cilenti L, Di Gregorio J, Mahar R, Liu F, Ambivero CT, Periasamy M, Merritt ME, Zervos AS. Inactivation of mitochondrial MUL1 E3 ubiquitin ligase deregulates mitophagy and prevents diet-induced obesity in mice. Front Mol Biosci 2024; 11:1397565. [PMID: 38725872 PMCID: PMC11079312 DOI: 10.3389/fmolb.2024.1397565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 04/05/2024] [Indexed: 05/12/2024] Open
Abstract
Obesity is a growing epidemic affecting millions of people worldwide and a major risk factor for a multitude of chronic diseases and premature mortality. Accumulating evidence suggests that mitochondria have a profound role in diet-induced obesity and the associated metabolic changes, but the molecular mechanisms linking mitochondria to obesity remain poorly understood. Our studies have identified a new function for mitochondrial MUL1 E3 ubiquitin ligase, a protein known to regulate mitochondrial dynamics and mitophagy, in the control of energy metabolism and lipogenesis. Genetic deletion of Mul1 in mice impedes mitophagy and presents a metabolic phenotype that is resistant to high-fat diet (HFD)-induced obesity and metabolic syndrome. Several metabolic and lipidomic pathways are perturbed in the liver and white adipose tissue (WAT) of Mul1(-/-) animals on HFD, including the one driven by Stearoyl-CoA Desaturase 1 (SCD1), a pivotal regulator of lipid metabolism and obesity. In addition, key enzymes crucial for lipogenesis and fatty acid oxidation such as ACC1, FASN, AMPK, and CPT1 are also modulated in the absence of MUL1. The concerted action of these enzymes, in the absence of MUL1, results in diminished fat storage and heightened fatty acid oxidation. Our findings underscore the significance of MUL1-mediated mitophagy in regulating lipogenesis and adiposity, particularly in the context of HFD. Consequently, our data advocate the potential of MUL1 as a therapeutic target for drug development in the treatment of obesity, insulin resistance, NAFLD, and cardiometabolic diseases.
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Affiliation(s)
- Lucia Cilenti
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Jacopo Di Gregorio
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Rohit Mahar
- Department of Chemistry, Hemvati Nandan Bahuguna Garhwal University (A Central University), Srinagar Garhwal, Uttarakhand, India
| | - Fei Liu
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Camilla T. Ambivero
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Muthu Periasamy
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Antonis S. Zervos
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
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Febo M, Mahar R, Rodriguez NA, Buraima J, Pompilus M, Pinto AM, Grudny MM, Bruijnzeel AW, Merritt ME. Age-related differences in affective behaviors in mice: possible role of prefrontal cortical-hippocampal functional connectivity and metabolomic profiles. Front Aging Neurosci 2024; 16:1356086. [PMID: 38524115 PMCID: PMC10957556 DOI: 10.3389/fnagi.2024.1356086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/28/2024] [Indexed: 03/26/2024] Open
Abstract
Introduction The differential expression of emotional reactivity from early to late adulthood may involve maturation of prefrontal cortical responses to negative valence stimuli. In mice, age-related changes in affective behaviors have been reported, but the functional neural circuitry warrants further investigation. Methods We assessed age variations in affective behaviors and functional connectivity in male and female C57BL6/J mice. Mice aged 10, 30 and 60 weeks (wo) were tested over 8 weeks for open field activity, sucrose preference, social interactions, fear conditioning, and functional neuroimaging. Prefrontal cortical and hippocampal tissues were excised for metabolomics. Results Our results indicate that young and old mice differ significantly in affective behavioral, functional connectome and prefrontal cortical-hippocampal metabolome. Young mice show a greater responsivity to novel environmental and social stimuli compared to older mice. Conversely, late middle-aged mice (60wo group) display variable patterns of fear conditioning and during re-testing in a modified context. Functional connectivity between a temporal cortical/auditory cortex network and subregions of the anterior cingulate cortex and ventral hippocampus, and a greater network modularity and assortative mixing of nodes was stronger in young versus older adult mice. Metabolome analyses identified differences in several essential amino acids between 10wo mice and the other age groups. Discussion The results support differential expression of 'emotionality' across distinct stages of the mouse lifespan involving greater prefrontal-hippocampal connectivity and neurochemistry.
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Affiliation(s)
- Marcelo Febo
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Rohit Mahar
- Department of Chemistry, Hemvati Nandan Bahuguna Garhwal University (A Central University), Srinagar Garhwal, Uttarakhand, India
| | - Nicholas A. Rodriguez
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Joy Buraima
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Marjory Pompilus
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Aeja M. Pinto
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Matteo M. Grudny
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Adriaan W. Bruijnzeel
- Department of Psychiatry, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL, United States
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, United States
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3
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Febo M, Mahar R, Rodriguez NA, Buraima J, Pompilus M, Pinto AM, Grudny MM, Bruijnzeel AW, Merritt ME. Age-Related Differences in Affective Behaviors in Mice: Possible Role of Prefrontal Cortical-Hippocampal Functional Connectivity and Metabolomic Profiles. bioRxiv 2024:2023.11.13.566691. [PMID: 38014219 PMCID: PMC10680600 DOI: 10.1101/2023.11.13.566691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The differential expression of emotional reactivity from early to late adulthood may involve maturation of prefrontal cortical responses to negative valence stimuli. In mice, age-related changes in affective behaviors have been reported, but the functional neural circuitry warrants further investigation. We assessed age variations in affective behaviors and functional connectivity in male and female C57BL6/J mice. Mice aged 10, 30 and 60 weeks (wo) were tested over 8 weeks for open field activity, sucrose preference, social interactions, fear conditioning, and functional neuroimaging. Prefrontal cortical and hippocampal tissues were excised for metabolomics. Our results indicate that young and old mice differ significantly in affective behavioral, functional connectome and prefrontal cortical-hippocampal metabolome. Young mice show a greater responsivity to novel environmental and social stimuli compared to older mice. Conversely, late middle-aged mice (60wo group) display variable patterns of fear conditioning and with re-testing with a modified context. Functional connectivity between a temporal cortical/auditory cortex network and subregions of the anterior cingulate cortex and ventral hippocampus, and a greater network modularity and assortative mixing of nodes was stronger in young versus older adult mice. Metabolome analyses identified differences in several essential amino acids between 10wo mice and the other age groups. The results support differential expression of 'emotionality' across distinct stages of the mouse lifespan involving greater prefrontal-hippocampal connectivity and neurochemistry.
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Rushin A, McLeod MA, Ragavan M, Merritt ME. Observing exocrine pancreas metabolism using a novel pancreas perfusion technique in combination with hyperpolarized [1- 13 C]pyruvate. Magn Reson Chem 2023; 61:748-758. [PMID: 37482899 PMCID: PMC10800648 DOI: 10.1002/mrc.5382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/25/2023]
Abstract
In a clinical setting, ex vivo perfusions are routinely used to maintain and assess organ viability prior to transplants. Organ perfusions are also a model system to examine metabolic flux while retaining the local physiological structure, with significant success using hyperpolarized (HP) 13 C NMR in this context. We use a novel exocrine pancreas perfusion technique via the common bile duct to assess acinar cell metabolism with HP [1-13 C]pyruvate. The exocrine component of the pancreas produces digestive enzymes through the ductal system and is often neglected in research on the pancreas. Real-time production of [1-13 C]lactate, [1-13 C]alanine, [1-13 C]malate, [4-13 C]malate, [1-13 C]aspartate, and H13 CO3 - was detected. The appearance of these resonances indicates flux through both pyruvate dehydrogenase and pyruvate carboxylase. We studied excised pancreata from C57BL/6J mice and NOD.Rag1-/- .AI4α/β mice, a commonly used model of Type 1 Diabetes (T1D). Pancreata from the T1D mice displayed increased lactate to alanine ratio without changes in oxygen consumption, signifying increased cytosolic NADH levels. The mass isotopologue analysis of the extracted pancreas tissue using gas chromatography-mass spectrometry revealed confirmatory 13 C enrichment in multiple TCA cycle metabolites that are products of pyruvate carboxylation. The methodology presented here has the potential to provide insight into mechanisms underlying several pancreatic diseases, such as diabetes, pancreatitis, and pancreatic cancer.
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Affiliation(s)
- Anna Rushin
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marc A. McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mukundan Ragavan
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
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Chang MC, Staklinski SJ, Merritt ME, Kilberg MS. A method for measurement of human asparagine synthetase (ASNS) activity and application to ASNS protein variants associated with ASNS deficiency. Biol Methods Protoc 2023; 8:bpad026. [PMID: 37965492 PMCID: PMC10641120 DOI: 10.1093/biomethods/bpad026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 11/16/2023] Open
Abstract
Human asparagine synthetase (ASNS) catalyzes the conversion of aspartate to asparagine in an ATP-dependent reaction that utilizes glutamine as a nitrogen source while generating glutamate, AMP, and pyrophosphate as additional products. Asparagine Synthetase Deficiency (ASNSD) is an inborn error of metabolism in which children present with homozygous or compound heterozygous mutations in the ASNS gene. These mutations result in ASNS variant protein expression. It is believed that these variant ASNS proteins have reduced enzymatic activity or stability resulting in a lack of sufficient asparagine production for cell function. Reduced asparagine production by ASNS appears to severely hinder fetal brain development. Although a variety of approaches for assaying ASNS activity have been reported, we present here a straightforward method for the in vitro enzymatic analysis by detection of AMP production. Our method overcomes limitations in technical feasibility, signal detection, and reproducibility experienced by prior methods like high-performance liquid chromatography, ninhydrin staining, and radioactive tracing. After purification of FLAG-tagged R49Q, G289A, and T337I ASNS variants from stably expressing HEK 293T cells, this method revealed a reduction in activity of 90, 36, and 96%, respectively. Thus, ASNS protein expression and purification, followed by enzymatic activity analysis, has provided a relatively simple protocol to evaluate structure-function relationships for ASNS variants reported for ASNSD patients.
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Affiliation(s)
- Mario C Chang
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, United States
| | - Stephen J Staklinski
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, United States
- School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, United States
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, United States
| | - Michael S Kilberg
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, United States
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6
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Cai F, Bezwada D, Cai L, Mahar R, Wu Z, Chang MC, Pachnis P, Yang C, Kelekar S, Gu W, Brooks B, Ko B, Vu HS, Mathews TP, Zacharias LG, Martin-Sandoval M, Do D, Oaxaca KC, Jin ES, Margulis V, Malloy CR, Merritt ME, DeBerardinis RJ. Comprehensive isotopomer analysis of glutamate and aspartate in small tissue samples. Cell Metab 2023; 35:1830-1843.e5. [PMID: 37611583 PMCID: PMC10732579 DOI: 10.1016/j.cmet.2023.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 07/13/2023] [Accepted: 07/28/2023] [Indexed: 08/25/2023]
Abstract
Stable isotopes are powerful tools to assess metabolism. 13C labeling is detected using nuclear magnetic resonance (NMR) spectroscopy or mass spectrometry (MS). MS has excellent sensitivity but generally cannot discriminate among different 13C positions (isotopomers), whereas NMR is less sensitive but reports some isotopomers. Here, we develop an MS method that reports all 16 aspartate and 32 glutamate isotopomers while requiring less than 1% of the sample used for NMR. This method discriminates between pathways that result in the same number of 13C labels in aspartate and glutamate, providing enhanced specificity over conventional MS. We demonstrate regional metabolic heterogeneity within human tumors, document the impact of fumarate hydratase (FH) deficiency in human renal cancers, and investigate the contributions of tricarboxylic acid (TCA) cycle turnover and CO2 recycling to isotope labeling in vivo. This method can accompany NMR or standard MS to provide outstanding sensitivity in isotope-labeling experiments, particularly in vivo.
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Affiliation(s)
- Feng Cai
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Divya Bezwada
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ling Cai
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Quantitative Biomedical Research Center, Department of Population and Data Sciences, UT Southwestern Medical Center, Dallas, TX 75390, USA; Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA
| | - Zheng Wu
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mario C Chang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA
| | - Panayotis Pachnis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Chendong Yang
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sherwin Kelekar
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wen Gu
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bailey Brooks
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bookyung Ko
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hieu S Vu
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Thomas P Mathews
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lauren G Zacharias
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Misty Martin-Sandoval
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Duyen Do
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - K Celeste Oaxaca
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Eunsook S Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vitaly Margulis
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Veterans Affairs North Texas Healthcare System, Dallas, TX 75216, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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7
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Chang MC, Staklinski SJ, Malut VR, Pierre GL, Kilberg MS, Merritt ME. Metabolomic Profiling of Asparagine Deprivation in Asparagine Synthetase Deficiency Patient-Derived Cells. Nutrients 2023; 15:1938. [PMID: 37111157 PMCID: PMC10145675 DOI: 10.3390/nu15081938] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
The natural amino acid asparagine (Asn) is required by cells to sustain function and proliferation. Healthy cells can synthesize Asn through asparagine synthetase (ASNS) activity, whereas specific cancer and genetically diseased cells are forced to obtain asparagine from the extracellular environment. ASNS catalyzes the ATP-dependent synthesis of Asn from aspartate by consuming glutamine as a nitrogen source. Asparagine Synthetase Deficiency (ASNSD) is a disease that results from biallelic mutations in the ASNS gene and presents with congenital microcephaly, intractable seizures, and progressive brain atrophy. ASNSD often leads to premature death. Although clinical and cellular studies have reported that Asn deprivation contributes to the disease symptoms, the global metabolic effects of Asn deprivation on ASNSD-derived cells have not been studied. We analyzed two previously characterized cell culture models, lymphoblastoids and fibroblasts, each carrying unique ASNS mutations from families with ASNSD. Metabolomics analysis demonstrated that Asn deprivation in ASNS-deficient cells led to disruptions across a wide range of metabolites. Moreover, we observed significant decrements in TCA cycle intermediates and anaplerotic substrates in ASNS-deficient cells challenged with Asn deprivation. We have identified pantothenate, phenylalanine, and aspartate as possible biomarkers of Asn deprivation in normal and ASNSD-derived cells. This work implies the possibility of a novel ASNSD diagnostic via targeted biomarker analysis of a blood draw.
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Affiliation(s)
- Mario C. Chang
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Stephen J. Staklinski
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
- School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Vinay R. Malut
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Geraldine L. Pierre
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Michael S. Kilberg
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Frost CJ, Ramirez-Mata A, Khattri RB, Merritt ME, Frost SC. Effects of β-caryophyllene and oxygen availability on cholesterol and fatty acids in breast cancer cells. PLoS One 2023; 18:e0281396. [PMID: 36893152 PMCID: PMC9997903 DOI: 10.1371/journal.pone.0281396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/21/2023] [Indexed: 03/10/2023] Open
Abstract
Hypoxia is a common feature of most solid tumors, one that favors tumor progression and limits treatment effectiveness. Targeting hypoxia has long been a goal in cancer therapy, by identifying factors that reverse or ameliorate the effects of hypoxia on cancer cells. We, and others, have shown that β-caryophyllene (BCP) exhibits anti-proliferative properties in cancer cells. We have further shown that non-cytotoxic concentrations of BCP affect cholesterol and lipid biosynthesis in hypoxic hBrC cells at both transcriptional and translational levels. This led us to hypothesize that BCP may reverse the hypoxic phenotype in hBrC cells. To test this, we determined the effect of BCP on hypoxic sensitive pathways, including oxygen consumption, glycolysis, oxidative stress, cholesterol and fatty acid biosynthesis, and ERK activation. While each of these studies revealed new information on the regulation by hypoxia and BCP, only the lipidomic studies showed reversal of hypoxic-dependent effects by BCP. These later studies showed that hypoxia-treated samples lowered monounsaturated fatty acid levels, shifting the saturation ratios of the fatty acid pools. This signature was ameliorated by sub-lethal concentrations of BCP, possibly through an effect on the C:16 fatty acid saturation ratios. This is consistent with BCP-induced upregulation of the stearoyl-CoA desaturase (SCD) gene, observed previously. This suggests that BCP may interfere with the lipid signature modulated by hypoxia which could have consequences for membrane biosynthesis or composition, both of which are important for cell replication.
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Affiliation(s)
- Christopher J. Frost
- BIO5 Institute, University of Arizona, Tucson, AZ, United States of America
- Department of Biology, University of Louisville, Louisville, KY, United States of America
| | - Andrea Ramirez-Mata
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States of America
| | - Ram B. Khattri
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States of America
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States of America
| | - Susan C. Frost
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States of America
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Staklinski SJ, Chang MC, Ahrens‐Nicklas RC, Kaur S, Stefanatos AK, Dudenhausen EE, Merritt ME, Kilberg MS. Characterizing asparagine synthetase deficiency variants in lymphoblastoid cell lines. JIMD Rep 2023; 64:167-179. [PMID: 36873094 PMCID: PMC9981421 DOI: 10.1002/jmd2.12356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/01/2022] [Accepted: 12/06/2022] [Indexed: 01/08/2023] Open
Abstract
Asparagine synthetase (ASNS) catalyzes the synthesis of asparagine (Asn) from aspartate and glutamine. Biallelic mutations in the ASNS gene result in ASNS Deficiency (ASNSD). Children with ASNSD exhibit congenital microcephaly, epileptic-like seizures, and continued brain atrophy, often leading to premature mortality. This report describes a 4-year-old male with global developmental delay and seizures with two novel mutations in the ASNS gene, c.614A > C (maternal) and c.1192dupT (paternal) encoding p.H205P and p.Y398Lfs*4 variants, respectively. We employed the novel use of immortalized lymphoblastoid cell lines (LCL) to show that the proliferation of the heterozygotic parental LCL was not severely affected by culture in Asn-free medium, but growth of the child's cells was suppressed by about 50%. Asn production by the LCL from both the father and the child was significantly decreased relative to the mother's cells. mRNA and protein analysis of the paternal LCL cells for the Y398Lfs*4 variant revealed reductions in both. Attempts to ectopically express the truncated Y398Lfs*4 variant in either HEK293T or ASNS-null cells resulted in little or no detectable protein. Expression and purification of the H205P variant from HEK293T cells revealed enzymatic activity similar to wild-type ASNS. Stable expression of WT ASNS rescued the growth of ASNS-null JRS cells in Asn-free medium and the H205P variant was only slightly less effective. However, the Y398Lfs*4 variant appeared to be unstable in JRS cells. These results indicate that co-expression of the H205P and Y398Lfs*4 variants leads to a significant reduction in Asn synthesis and cellular growth.
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Affiliation(s)
- Stephen J. Staklinski
- Department of Biochemistry and Molecular BiologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
- School of Biological SciencesCold Spring Harbor Laboratory, Cold Spring HarborNew YorkNew YorkUSA
| | - Mario C. Chang
- Department of Biochemistry and Molecular BiologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
| | - Rebecca C. Ahrens‐Nicklas
- Division of Human Genetics, Department of PediatricsChildren's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Shagun Kaur
- Division of Human Genetics, Department of PediatricsChildren's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Arianna K. Stefanatos
- Department of Child and Adolescent Psychiatry and Behavioral SciencesChildren's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Elizabeth E. Dudenhausen
- Department of Biochemistry and Molecular BiologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular BiologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
| | - Michael S. Kilberg
- Department of Biochemistry and Molecular BiologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
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10
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Coelho M, Mahar R, Belew GD, Torres A, Barosa C, Cabral F, Viegas I, Gastaldelli A, Mendes VM, Manadas B, Jones JG, Merritt ME. Enrichment of hepatic glycogen and plasma glucose from H₂ 18 O informs gluconeogenic and indirect pathway fluxes in naturally feeding mice. NMR Biomed 2023; 36:e4837. [PMID: 36151589 PMCID: PMC9845176 DOI: 10.1002/nbm.4837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Deuterated water (2 H2 O) is a widely used tracer of carbohydrate biosynthesis in both preclinical and clinical settings, but the significant kinetic isotope effects (KIE) of 2 H can distort metabolic information and mediate toxicity. 18 O-water (H2 18 O) has no significant KIE and is incorporated into specific carbohydrate oxygens via well-defined mechanisms, but to date it has not been evaluated in any animal model. Mice were given H2 18 O during overnight feeding and 18 O-enrichments of liver glycogen, triglyceride glycerol (TG), and blood glucose were quantified by 13 C NMR and mass spectrometry (MS). Enrichment of oxygens 5 and 6 relative to body water informed indirect pathway contributions from the Krebs cycle and triose phosphate sources. Compared with mice fed normal chow (NC), mice whose NC was supplemented with a fructose/glucose mix (i.e., a high sugar [HS] diet) had significantly higher indirect pathway contributions from triose phosphate sources, consistent with fructose glycogenesis. Blood glucose and liver TG 18 O-enrichments were quantified by MS. Blood glucose 18 O-enrichment was significantly higher for HS versus NC mice and was consistent with gluconeogenic fructose metabolism. TG 18 O-enrichment was extensive for both NC and HS mice, indicating a high turnover of liver triglyceride, independent of diet. Thus H2 18 O informs hepatic carbohydrate biosynthesis in similar detail to 2 H2 O but without KIE-associated risks.
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Affiliation(s)
- Margarida Coelho
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
- Department of Chemistry, Faculty of Sciences and TechnologyUniversity of CoimbraCoimbraPortugal
| | - Rohit Mahar
- Department of Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFloridaUSA
| | - Getachew D. Belew
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Alejandra Torres
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Cristina Barosa
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Fernando Cabral
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Ivan Viegas
- Center for Functional Ecology, Department of Life SciencesUniversity of CoimbraCoimbraPortugal
| | | | - Vera M. Mendes
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Bruno Manadas
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - John G. Jones
- CNC ‐ Center for Neurosciences and Cell BiologyUniversity of CoimbraCoimbraPortugal
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFloridaUSA
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11
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Lei J, Mahar R, Chang MC, Collins J, Merritt ME, Garrett TJ, Yost RA. Segmented Flow Strategies for Integrating Liquid Chromatography-Mass Spectrometry with Nuclear Magnetic Resonance for Lipidomics. Anal Chem 2023; 95:10.1021/acs.analchem.2c03974. [PMID: 36630396 PMCID: PMC10870252 DOI: 10.1021/acs.analchem.2c03974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Building an accurate lipid inventory relies on coordinated information from orthogonal analytical capabilities. Integrating the familiar workflow of liquid chromatography (LC), high-resolution mass spectrometry (HRMS), and tandem mass spectrometry (MS/MS) with proton nuclear magnetic resonance spectroscopy (1H NMR) would be ideal for building that inventory. For absolute lipid structural elucidation, LC-HRMS/MS can provide lower-level structural information with superior sensitivity, while 1H NMR can provide invaluable higher-order structural information for the disambiguation of isomers with absolute chemical specificity. Digitization of the LC eluent followed by splitting the microfractions into two flow paths in a defined ratio for HRMS/MS and NMR would be the ideal strategy to permit correlation of the MS and NMR data as a function of chromatographic retention time. Here, we report an active segmentation platform to transform analytical flow rate LC eluent into parallel microliter segmented flow queues for high confidence correlation of the MS, MS/MS, and NMR data. The practical details in implementing this strategy to achieve an integrated LC-MS-NMR platform are presented, including the development of an active segmentation technology using a four-port two-way valve to transform the LC eluent into parallel segmented flows for online MS analysis followed by offline segment-specific 1H NMR and optimization of the detector response toward segmented flow. To demonstrate the practicality of this novel platform, it was tested using lipid mixture samples.
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Affiliation(s)
- Jiajun Lei
- Department of Chemistry, University of Florida, Gainesville, Florida32611, United States
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida32610, United States
| | - Mario C Chang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida32610, United States
| | - James Collins
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida32610, United States
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida32610, United States
| | - Timothy J Garrett
- Department of Chemistry, University of Florida, Gainesville, Florida32611, United States
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, Florida32610, United States
| | - Richard A Yost
- Department of Chemistry, University of Florida, Gainesville, Florida32611, United States
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, Florida32610, United States
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12
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Khattri RB, Puglise J, Ryan TE, Walter GA, Merritt ME, Barton ER. Isolated murine skeletal muscles utilize pyruvate over glucose for oxidation. Metabolomics 2022; 18:105. [PMID: 36480060 PMCID: PMC9732067 DOI: 10.1007/s11306-022-01948-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/29/2022] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Fuel sources for skeletal muscle tissue include carbohydrates and fatty acids, and utilization depends upon fiber type, workload, and substrate availability. The use of isotopically labeled substrate tracers combined with nuclear magnetic resonance (NMR) enables a deeper examination of not only utilization of substrates by a given tissue, but also their contribution to tricarboxylic acid (TCA) cycle intermediates. OBJECTIVES The goal of this study was to determine the differential utilization of substrates in isolated murine skeletal muscle, and to evaluate how isopotomer anlaysis provided insight into skeletal muscle metabolism. METHODS Isolated C57BL/6 mouse hind limb muscles were incubated in oxygenated solution containing uniformly labeled 13C6 glucose, 13C3 pyruvate, or 13C2 acetate at room temperature. Isotopomer analysis of 13C labeled glutamate was performed on pooled extracts of isolated soleus and extensor digitorum longus (EDL) muscles. RESULTS Pyruvate and acetate were more avidly consumed than glucose with resultant increases in glutamate labeling in both muscle groups. Glucose incubation resulted in glutamate labeling, but with high anaplerotic flux in contrast to the labeling by pyruvate. Muscle fiber type distinctions were evident by differences in lactate enrichment and extent of substrate oxidation. CONCLUSION Isotope tracing experiments in isolated muscles reveal that pyruvate and acetate are avidly oxidized by isolated soleus and EDL muscles, whereas glucose labeling of glutamate is accompanied by high anaplerotic flux. We believe our results may set the stage for future examination of metabolic signatures of skeletal muscles from pre-clinical models of aging, type-2 diabetes and neuromuscular disease.
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Affiliation(s)
- Ram B Khattri
- Department of Applied Physiology and Kinesiology, College of Health & Human Performance, University of Florida, 124 Florida Gym, 1864 Stadium Road, Gainesville, FL, 32611, USA
| | - Jason Puglise
- Department of Applied Physiology and Kinesiology, College of Health & Human Performance, University of Florida, 124 Florida Gym, 1864 Stadium Road, Gainesville, FL, 32611, USA
| | - Terence E Ryan
- Department of Applied Physiology and Kinesiology, College of Health & Human Performance, University of Florida, 124 Florida Gym, 1864 Stadium Road, Gainesville, FL, 32611, USA
- Myology Institute, University of Florida, Gainesville, USA
- Center for Exercise Science, University of Florida, Gainesville, FL, USA
| | - Glenn A Walter
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, USA
- Myology Institute, University of Florida, Gainesville, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, USA
| | - Elisabeth R Barton
- Department of Applied Physiology and Kinesiology, College of Health & Human Performance, University of Florida, 124 Florida Gym, 1864 Stadium Road, Gainesville, FL, 32611, USA.
- Myology Institute, University of Florida, Gainesville, USA.
- Center for Exercise Science, University of Florida, Gainesville, FL, USA.
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13
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Merritt ME. Editorial for "Whole-Abdomen Metabolic Imaging of Healthy Volunteers Using Hyperpolarized [1- 13 C]pyruvate MRI". J Magn Reson Imaging 2022; 56:1807-1808. [PMID: 35416358 DOI: 10.1002/jmri.28202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 01/04/2023] Open
Affiliation(s)
- Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Florida, USA
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14
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Mahar R, Ragavan M, Chang MC, Hardiman S, Moussatche N, Behar A, Renne R, Merritt ME. Metabolic signatures associated with oncolytic myxoma viral infections. Sci Rep 2022; 12:12599. [PMID: 35871072 PMCID: PMC9308783 DOI: 10.1038/s41598-022-15562-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/27/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractOncolytic viral therapy is a recent advance in cancer treatment, demonstrating promise as a primary treatment option. To date, the secondary metabolic effects of viral infection in cancer cells has not been extensively studied. In this work, we have analyzed early-stage metabolic changes in cancer cells associated with oncolytic myxoma virus infection. Using GC–MS based metabolomics, we characterized the myxoma virus infection induced metabolic changes in three cancer cell lines—small cell (H446) and non-small cell (A549) lung cancers, and glioblastoma (SFxL). We show that even at an early stage (6 and 12 h) myxoma infection causes profound changes in cancer cell metabolism spanning several important pathways such as the citric acid cycle, fatty acid metabolism, and amino acid metabolism. In general, the metabolic effects of viral infection across cell lines are not conserved. However, we have identified several candidate metabolites that can potentially serve as biomarkers for monitoring oncolytic viral action in general.
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15
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Staklinski SJ, Chang MC, Yu F, Collins Ruff K, Franz DN, Qian Z, Bloom LB, Merritt ME, McKenna R, Kilberg MS. Cellular and molecular characterization of two novel asparagine synthetase gene mutations linked to asparagine synthetase deficiency. J Biol Chem 2022; 298:102385. [PMID: 35985424 PMCID: PMC9478401 DOI: 10.1016/j.jbc.2022.102385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 11/22/2022] Open
Abstract
Asparagine synthetase (ASNS) catalyzes synthesis of asparagine (Asn) and Glu from Asp and Gln in an ATP-dependent reaction. Asparagine synthetase deficiency (ASNSD) results from biallelic mutations in the ASNS gene. Affected children exhibit congenital microcephaly, continued brain atrophy, seizures, and often premature mortality. However, the underlying mechanisms are unclear. This report describes a compound heterozygotic ASNSD child with two novel mutations in the ASNS gene, c.1118G>T (paternal) and c.1556G>A (maternal), that lead to G373V or R519H ASNS variants. Structural mapping suggested that neither variant participates directly in catalysis. Growth of cultured fibroblasts from either parent was unaffected in Asn-free medium, whereas growth of the child's cells was suppressed by about 50%. Analysis of Asn levels unexpectedly revealed that extracellular rather than intracellular Asn correlated with the reduced proliferation during incubation of the child's cells in Asn-free medium. Our attempts to ectopically express the G373V variant in either HEK293T or JRS cells resulted in minimal protein production, suggesting instability. Protein expression and purification from HEK293T cells revealed reduced activity for the R519H variant relative to WT ASNS. Expression of WT ASNS in ASNS-null JRS cells resulted in nearly complete rescue of growth in Asn-free medium, whereas we observed no proliferation for the cells expressing either the G373V or R519H variant. These results support the conclusion that the coexpression of the G373V and R519H ASNS variants leads to significantly reduced Asn synthesis, which negatively impacts cellular growth. These observations are consistent with the ASNSD phenotype.
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Affiliation(s)
- Stephen J Staklinski
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Mario C Chang
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Fang Yu
- Department of Medicine, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Kathleen Collins Ruff
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - David N Franz
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Zhijian Qian
- Department of Medicine, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Linda B Bloom
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Michael S Kilberg
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA.
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16
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Thomas JN, Johnston TL, Litvak IM, Ramaswamy V, Merritt ME, Rocca JR, Edison AS, Brey WW. Implementing High Q-Factor HTS Resonators to Enhance Probe Sensitivity in 13C NMR Spectroscopy. J Phys Conf Ser 2022; 2323:012030. [PMID: 36187328 PMCID: PMC9524303 DOI: 10.1088/1742-6596/2323/1/012030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Nuclear magnetic resonance spectroscopy (NMR) probes using thin-film high temperature superconducting (HTS) resonators provide exceptional mass sensitivity in small-sample NMR experiments for natural products chemistry and metabolomics. We report improvements in sensitivity to our 1.5 mm 13C-optimized NMR probe based on HTS resonators. The probe has a sample volume of 35 microliters and operates in a 14.1 T magnet. The probe also features HTS resonators for 1H transmission and detection and the 2H lock. The probe utilizes a 13C resonator design that provides greater efficiency than our previous design. The quality factor of the new resonator in the 14.1 T background field was measured to be 4,300, which is over 3x the value of the previous design. To effectively implement the improved quality factor, we demonstrate the effect of adding a shorted transmission line stub to increase the bandwidth and reduce the rise/fall time of 13C irradiation pulses. Initial NMR measurements verify 13C NMR sensitivity is significantly improved while preserving detection bandwidth. The probe will be used for applications in metabolomics.
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Affiliation(s)
- J N Thomas
- National High Magnetic Field Laboratory, Tallahassee FL, USA
| | - T L Johnston
- National High Magnetic Field Laboratory, Tallahassee FL, USA
| | - I M Litvak
- National High Magnetic Field Laboratory, Tallahassee FL, USA
| | | | | | - J R Rocca
- University of Florida, Gainesville FL, USA
| | | | - W W Brey
- National High Magnetic Field Laboratory, Tallahassee FL, USA
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17
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Chang MC, Mahar R, McLeod MA, Giacalone AG, Huang X, Boothman DA, Merritt ME. Synergistic Effect of β-Lapachone and Aminooxyacetic Acid on Central Metabolism in Breast Cancer. Nutrients 2022; 14:3020. [PMID: 35893874 PMCID: PMC9331106 DOI: 10.3390/nu14153020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/19/2022] [Accepted: 07/19/2022] [Indexed: 11/20/2022] Open
Abstract
The compound β-lapachone, a naturally derived naphthoquinone, has been utilized as a potent medicinal nutrient to improve health. Over the last twelve years, numerous reports have demonstrated distinct associations of β-lapachone and NAD(P)H: quinone oxidoreductase 1 (NQO1) protein in the amelioration of various diseases. Comprehensive research of NQO1 bioactivity has clearly confirmed the tumoricidal effects of β-lapachone action through NAD+-keresis, in which severe DNA damage from reactive oxygen species (ROS) production triggers a poly-ADP-ribose polymerase-I (PARP1) hyperactivation cascade, culminating in NAD+/ATP depletion. Here, we report a novel combination strategy with aminooxyacetic acid (AOA), an aspartate aminotransferase inhibitor that blocks the malate-aspartate shuttle (MAS) and synergistically enhances the efficacy of β-lapachone metabolic perturbation in NQO1+ breast cancer. We evaluated metabolic turnover in MDA-MB-231 NQO1+, MDA-MB-231 NQO1-, MDA-MB-468, and T47D cancer cells by measuring the isotopic labeling of metabolites from a [U-13C]glucose tracer. We show that β-lapachone treatment significantly hampers lactate secretion by ~85% in NQO1+ cells. Our data demonstrate that combinatorial treatment decreases citrate, glutamate, and succinate enrichment by ~14%, ~50%, and ~65%, respectively. Differences in citrate, glutamate, and succinate fractional enrichments indicate synergistic effects on central metabolism based on the coefficient of drug interaction. Metabolic modeling suggests that increased glutamine anaplerosis is protective in the case of MAS inhibition.
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Affiliation(s)
- Mario C. Chang
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (M.C.C.); (R.M.); (M.A.M.); (A.G.G.)
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (M.C.C.); (R.M.); (M.A.M.); (A.G.G.)
| | - Marc A. McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (M.C.C.); (R.M.); (M.A.M.); (A.G.G.)
| | - Anthony G. Giacalone
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (M.C.C.); (R.M.); (M.A.M.); (A.G.G.)
| | - Xiumei Huang
- Department of Radiation Oncology, Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
| | - David A. Boothman
- Department of Radiation Oncology, Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (M.C.C.); (R.M.); (M.A.M.); (A.G.G.)
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18
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Cilenti L, Mahar R, Di Gregorio J, Ambivero CT, Merritt ME, Zervos AS. Regulation of Metabolism by Mitochondrial MUL1 E3 Ubiquitin Ligase. Front Cell Dev Biol 2022; 10:904728. [PMID: 35846359 PMCID: PMC9277447 DOI: 10.3389/fcell.2022.904728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022] Open
Abstract
MUL1 is a multifunctional E3 ubiquitin ligase that is involved in various pathophysiological processes including apoptosis, mitophagy, mitochondrial dynamics, and innate immune response. We uncovered a new function for MUL1 in the regulation of mitochondrial metabolism. We characterized the metabolic phenotype of MUL1(-/-) cells using metabolomic, lipidomic, gene expression profiling, metabolic flux, and mitochondrial respiration analyses. In addition, the mechanism by which MUL1 regulates metabolism was investigated, and the transcription factor HIF-1α, as well as the serine/threonine kinase Akt2, were identified as the mediators of the MUL1 function. MUL1 ligase, through K48-specific polyubiquitination, regulates both Akt2 and HIF-1α protein level, and the absence of MUL1 leads to the accumulation and activation of both substrates. We used specific chemical inhibitors and activators of HIF-1α and Akt2 proteins, as well as Akt2(-/-) cells, to investigate the individual contribution of HIF-1α and Akt2 proteins to the MUL1-specific phenotype. This study describes a new function of MUL1 in the regulation of mitochondrial metabolism and reveals how its downregulation/inactivation can affect mitochondrial respiration and cause a shift to a new metabolic and lipidomic state.
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Affiliation(s)
- Lucia Cilenti
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Jacopo Di Gregorio
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Camilla T. Ambivero
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Antonis S. Zervos
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
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19
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Johnston TL, Edison AS, Ramaswamy V, Freytag N, Merritt ME, Thomas JN, Hooker JW, Litvak IM, Brey WW. Application of Counter-wound Multi-arm Spirals in HTS Resonator Design. IEEE Trans Appl Supercond 2022; 32:1500304. [PMID: 35449718 PMCID: PMC9017787 DOI: 10.1109/tasc.2022.3146109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Significant sensitivity improvements have been achieved by utilizing high temperature superconducting (HTS) resonators in nuclear magnetic resonance (NMR) probes. Many nuclei such as 13C benefit from strong excitation fields which cannot be produced by traditional HTS resonator designs. We investigate the use of double-sided, counter-wound multi-arm spiral HTS resonators with the aim of increasing the excitation field at the required nuclear Larmor frequency for 13C. When compared to double-sided, counter-wound spiral resonators with similar geometry, simulations indicate that the multi-arm spiral version develops a more uniform current distribution. Preliminary tests of a two-arm resonator indicate that it may produce a stronger excitation field.
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Affiliation(s)
- Taylor L Johnston
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with the Department of Chemistry and Biochemistry, Florida State University
| | | | | | | | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32601, USA
| | - Jeremy N Thomas
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA and also with the Department of Physics, Florida State University
| | - Jerris W Hooker
- Department of Electrical and Computer Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, USA
| | - Ilya M Litvak
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with Florida State University
| | - William W Brey
- National High Magnetic Laboratory, Tallahassee, FL 32310, USA and also with Florida State University
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20
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Mcleod M, Ragavan M, Giacalone A, Rushin A, Merritt ME. Real Time Measurement of Hepatic β‐oxidation with Deuterium Magnetic Resonance in Murine Models on a High Fat Diet. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r4643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marc Mcleod
- Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFL
| | - Mukundan Ragavan
- Biochemistry and Molecular BiologyUniversity of FloridaGainesvilleFL
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21
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Pillai S, Mahmud I, Mahar R, Griffith C, Langsen M, Nguyen J, Wojtkowiak JW, Swietach P, Gatenby RA, Bui MM, Merritt ME, McDonald P, Garrett TJ, Gillies RJ. Lipogenesis mediated by OGR1 regulates metabolic adaptation to acid stress in cancer cells via autophagy. Cell Rep 2022; 39:110796. [PMID: 35545051 PMCID: PMC9137419 DOI: 10.1016/j.celrep.2022.110796] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 03/03/2022] [Accepted: 04/15/2022] [Indexed: 12/12/2022] Open
Abstract
Malignant tumors exhibit altered metabolism resulting in a highly acidic extracellular microenvironment. Here, we show that cytoplasmic lipid droplet (LD) accumulation, indicative of a lipogenic phenotype, is a cellular adaption to extracellular acidity. LD marker PLIN2 is strongly associated with poor overall survival in breast cancer patients. Acid-induced LD accumulation is triggered by activation of the acid-sensing G-protein-coupled receptor (GPCR) OGR1, which is expressed highly in breast tumors. OGR1 depletion inhibits acid-induced lipid accumulation, while activation by a synthetic agonist triggers LD formation. Inhibition of OGR1 downstream signaling abrogates the lipogenic phenotype, which can be rescued with OGR1 ectopic expression. OGR1-depleted cells show growth inhibition under acidic growth conditions in vitro and tumor formation in vivo. Isotope tracing shows that the source of lipid precursors is primarily autophagy-derived ketogenic amino acids. OGR1-depleted cells are defective in endoplasmic reticulum stress response and autophagy and hence fail to accumulate LDs affecting survival under acidic stress.
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Affiliation(s)
- Smitha Pillai
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.
| | - Iqbal Mahmud
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Crystal Griffith
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Michael Langsen
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Jonathan Nguyen
- Analytical Microscopy Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Jonathan W Wojtkowiak
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics Parks Road, Oxford OX1 3PT, UK
| | - Robert A Gatenby
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA; Department of Radiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Marilyn M Bui
- Analytical Microscopy Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA; Department of Pathology, Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Patricia McDonald
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Timothy J Garrett
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Robert J Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA; Department of Radiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
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22
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Giacalone AG, Merritt ME, Ragavan M. Ex Vivo Hepatic Perfusion Through the Portal Vein in Mouse. J Vis Exp 2022:10.3791/63154. [PMID: 35343950 PMCID: PMC9258001 DOI: 10.3791/63154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Metabolic diseases such as diabetes, pre-diabetes, non-alcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH) are becoming increasingly common. Ex vivo liver perfusions allow for a comprehensive analysis of liver metabolism using nuclear magnetic resonance (NMR), in nutritional conditions that can be rigorously controlled. As in silico simulations remain a primarily theoretical means of assessing hormone actions and the effects of pharmaceutical intervention, the perfused liver remains one of the most valuable test beds for understanding hepatic metabolism. As these studies guide basic insights into hepatic physiology, results must be accurate and reproducible. The greatest factor in the reproducibility of ex vivo hepatic perfusion is the quality of surgery. Therefore, we have introduced an organized and streamlined method to perform ex vivo mouse liver perfusions in the context of in situ NMR experiments. We also describe a unique application and discuss common issues encountered in these studies. The overall purpose is to provide an uncomplicated guide to a technique we have refined over several years that we deem the golden standard for obtaining reproducible results in hepatic resections and perfusions in the context of in situ NMR experiments. The distance to the center of the field for the magnet as well as the inaccessibility of the tissue to intervention during the NMR experiment makes our methods novel.
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Affiliation(s)
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida;
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Ragavan M, McLeod MA, Rushin A, Merritt ME. Detecting de novo Hepatic Ketogenesis Using Hyperpolarized [2- 13C] Pyruvate. Front Physiol 2022; 13:832403. [PMID: 35197867 PMCID: PMC8859440 DOI: 10.3389/fphys.2022.832403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/14/2022] [Indexed: 11/28/2022] Open
Abstract
The role of ketones in metabolic health has progressed over the past two decades, moving from what was perceived as a simple byproduct of fatty acid oxidation to a central player in a multiplicity of disease states. Previous work with hyperpolarized (HP) 13C has shown that ketone production can be detected when using precursors that labeled acetyl-CoA at the C1 position, often in tissues that are not normally recognized as ketogenic. Here, we assay metabolism of HP [2-13C]pyruvate in the perfused mouse liver, a classic metabolic testbed where nutritional conditions can be precisely controlled. Livers perfused with long-chain fatty acids or the medium-chain fatty acid octanoate showed no evidence of ketogenesis in the 13C spectrum. In contrast, addition of dichloroacetate, a potent inhibitor of pyruvate dehydrogenase kinase, resulted in significant production of both acetoacetate and 3-hydroxybutyrate from the pyruvate precursor. This result indicates that ketones are readily produced from carbohydrates, but only in the case where pyruvate dehydrogenase activity is upregulated.
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Affiliation(s)
| | | | | | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, United States
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24
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Rahim M, Ragavan M, Deja S, Merritt ME, Burgess SC, Young JD. INCA 2.0: A tool for integrated, dynamic modeling of NMR- and MS-based isotopomer measurements and rigorous metabolic flux analysis. Metab Eng 2022; 69:275-285. [PMID: 34965470 PMCID: PMC8789327 DOI: 10.1016/j.ymben.2021.12.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 01/03/2023]
Abstract
Metabolic flux analysis (MFA) combines experimental measurements and computational modeling to determine biochemical reaction rates in live biological systems. Advancements in analytical instrumentation, such as nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), have facilitated chemical separation and quantification of isotopically enriched metabolites. However, no software packages have been previously described that can integrate isotopomer measurements from both MS and NMR analytical platforms and have the flexibility to estimate metabolic fluxes from either isotopic steady-state or dynamic labeling experiments. By applying physiologically relevant cardiac and hepatic metabolic models to assess NMR isotopomer measurements, we herein test and validate new modeling capabilities of our enhanced flux analysis software tool, INCA 2.0. We demonstrate that INCA 2.0 can simulate and regress steady-state 13C NMR datasets from perfused hearts with an accuracy comparable to other established flux assessment tools. Furthermore, by simulating the infusion of three different 13C acetate tracers, we show that MFA based on dynamic 13C NMR measurements can more precisely resolve cardiac fluxes compared to isotopically steady-state flux analysis. Finally, we show that estimation of hepatic fluxes using combined 13C NMR and MS datasets improves the precision of estimated fluxes by up to 50%. Overall, our results illustrate how the recently added NMR data modeling capabilities of INCA 2.0 can enable entirely new experimental designs that lead to improved flux resolution and can be applied to a wide range of biological systems and measurement time courses.
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Affiliation(s)
- Mohsin Rahim
- Department of Chemical and Biomolecular, Nashville, TN, 37212, USA
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Stanislaw Deja
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Shawn C Burgess
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular, Nashville, TN, 37212, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Engineering, Nashville, TN, 37212, USA.
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Abstract
Treatment of cancers with β-lapachone causes NAD(P)H: quinone oxidoreductase 1 (NQO1) to generate an unstable hydroquinone that regenerates itself in a futile cycle while producing reactive oxygen species (ROS) in the form of superoxide and subsequently hydrogen peroxide. Rapid accumulation of ROS damages DNA, hyperactivates poly-ADP-ribose polymerase-I, causes massive depletion of NAD+/ATP, and hampers glycolysis. Cells overexpressing NQO1 subsequently die rapidly through an NAD+-keresis mechanism. Assessing changes in glycolytic rates caused by NQO1 bioactivation would provide a means of assessing treatment efficacy, potentially lowering the chemotherapeutic dosage, and reducing off-target toxicities. NQO1-mediated changes in glycolytic flux were readily detected in A549 (lung), MiaPaCa2 (pancreatic), and HCT-116 (colon) cancer cell lines by 2H-NMR after administration of [2H7]glucose. The deuterated metabolic products 2H-lactate and HDO were quantified, and linear relationships with glucose consumption for both products were observed. The higher concentration of HDO compared to 2H-lactate allows for more sensitive measurement of the glycolytic flux in cancer. Gas chromatography-mass spectrometry analysis agreed with the NMR results and confirmed downregulated energy metabolism in NQO1+ cells after β-lapachone treatment. The demonstrated method is ideal for measuring glycolytic rates, the effects of chemotherapeutics that target glycolysis, and has the potential for in vivo translation.
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Affiliation(s)
| | | | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (R.M.); (M.C.C.)
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Ragavan M, McLeod MA, Giacalone AG, Merritt ME. Hyperpolarized Dihydroxyacetone Is a Sensitive Probe of Hepatic Gluconeogenic State. Metabolites 2021; 11:441. [PMID: 34357335 PMCID: PMC8307483 DOI: 10.3390/metabo11070441] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/23/2021] [Accepted: 07/01/2021] [Indexed: 11/25/2022] Open
Abstract
Type II diabetes and pre-diabetes are widely prevalent among adults. Elevated serum glucose levels are commonly treated by targeting hepatic gluconeogenesis for downregulation. However, direct measurement of hepatic gluconeogenic capacity is accomplished only via tracer metabolism approaches that rely on multiple assumptions, and are clinically intractable due to expense and time needed for the studies. We previously introduced hyperpolarized (HP) [2-13C]dihydroxyacetone (DHA) as a sensitive detector of gluconeogenic potential, and showed that feeding and fasting produced robust changes in the ratio of detected hexoses (6C) to trioses (3C) in the perfused liver. To confirm that this ratio is robust in the setting of treatment and hormonal control, we used ex vivo perfused mouse livers from BLKS mice (glucagon treated and metformin treated), and db/db mice. We confirm that the ratio of signal intensities of 6C to 3C in 13C nuclear magnetic resonance spectra post HP DHA administration is sensitive to hepatic gluconeogenic state. This method is directly applicable in vivo and can be implemented with existing technologies without the need for substantial modifications.
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Affiliation(s)
| | | | | | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; (M.R.); (M.A.M.); (A.G.G.)
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Myer C, Abdelrahman L, Banerjee S, Khattri RB, Merritt ME, Junk AK, Lee RK, Bhattacharya SK. Aqueous humor metabolite profile of pseudoexfoliation glaucoma is distinctive. Mol Omics 2021; 16:425-435. [PMID: 32149291 DOI: 10.1039/c9mo00192a] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pseudoexfoliation (PEX) is a known cause of secondary open angle glaucoma. PEX glaucoma is associated with structural and metabolic changes in the eye. Despite similarities, PEX and primary open angle glaucoma (POAG) may have differences in the composition of metabolites. We analyzed the metabolites of the aqueous humor (AH) of PEX subjects sequentially first using nuclear magnetic resonance (1H NMR: HSQC and TOCSY), and subsequently with liquid chromatography tandem mass spectrometry (LC-MS/MS) implementing isotopic ratio outlier analysis (IROA) quantification. The findings were compared with previous results for POAG and control subjects analyzed using identical sequential steps. We found significant differences in metabolites between the three conditions. Principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) indicated clear grouping based on the metabolomes of the three conditions. We used machine learning algorithms and a percentage set of the data to train, and utilized a different or larger dataset to test whether a trained model can correctly classify the test dataset as PEX, POAG or control. Three different algorithms: linear support vector machines (SVM), deep learning, and a neural network were used for prediction. They all accurately classified the test datasets based on the AH metabolome of the sample. We next compared the AH metabolome with known AH and TM proteomes and genomes in order to understand metabolic pathways that may contribute to alterations in the AH metabolome in PEX. We found potential protein/gene pathways associated with observed significant metabolite changes in PEX.
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Affiliation(s)
- Ciara Myer
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Leila Abdelrahman
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Santanu Banerjee
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA and Department of Surgery, University of Miami, Miami, Florida, USA
| | | | | | - Anna K Junk
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA and Miami Veterans Affairs Healthcare System, Miami, Florida, USA
| | - Richard K Lee
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. and Miami Integrative Metabolomics Research Center, University of Miami, Miami, Florida, USA
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Henry JA, Khattri RB, Guingab-Cagmat J, Merritt ME, Garrett TJ, Patterson JT, Lohr KE. Intraspecific variation in polar and nonpolar metabolite profiles of a threatened Caribbean coral. Metabolomics 2021; 17:60. [PMID: 34143280 DOI: 10.1007/s11306-021-01808-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 05/29/2021] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Research aimed at understanding intraspecific variation among corals could substantially increase understanding of coral biology and improve outcomes of active restoration efforts. Metabolomics is useful for identifying physiological drivers leading to variation among genotypes and has the capacity to improve our selection of candidate corals that express phenotypes beneficial to restoration. OBJECTIVES Our study aims to compare metabolomic profiles among known, unique genotypes of the threatened coral Acropora cervicornis. In doing so, we seek information related to the physiological characteristics driving variation among genotypes, which could aid in identifying genets with desirable traits for restoration. METHODS We applied proton nuclear magnetic resonance (1H-NMR) and liquid chromatography-mass spectrometry (LC-MS) to identify and compare metabolomic profiles for seven unique genotypes of A. cervicornis that previously exhibited phenotypic variation in a common garden coral nursery. RESULTS Significant variation in polar and nonpolar metabolite profiles was found among A. cervicornis genotypes. Despite difficulties identifying all significant metabolites driving separation among genotypes, our data support previous findings and further suggest metabolomic profiles differ among various genotypes of the threatened species A. cervicornis. CONCLUSION The implementation of metabolomic analyses allowed identification of several key metabolites driving separation among genotypes and expanded our understanding of the A. cervicornis metabolome. Although our research is specific to A. cervicornis, these findings have broad relevance for coral biology and active restoration. Furthermore, this study provides specific information on the understudied A. cervicornis metabolome and further confirmation that differences in metabolome structure could drive phenotypic variation among genotypes.
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Affiliation(s)
- Joseph A Henry
- Program in Fisheries and Aquatic Sciences, School of Forest, Fisheries, and Geomatics Sciences, University of Florida/IFAS, 7922 NW 71st Street, Gainesville, FL, 32653, USA.
| | - Ram B Khattri
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Joy Guingab-Cagmat
- Southeast Center for Integrated Metabolomics, Clinical and Translational Science Institute, University of Florida, Gainesville, FL, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Timothy J Garrett
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Joshua T Patterson
- Program in Fisheries and Aquatic Sciences, School of Forest, Fisheries, and Geomatics Sciences, University of Florida/IFAS, 7922 NW 71st Street, Gainesville, FL, 32653, USA
- The Florida Aquarium, Center for Conservation, 529 Estuary Shore Ln, Apollo Beach, FL, 33572-2205, USA
| | - Kathryn E Lohr
- Office of National Marine Sanctuaries, National Oceanic and Atmospheric Administration, Silver Spring, MD, USA
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Michel KA, Ragavan M, Walker CM, Merritt ME, Lai SY, Bankson JA. Comparison of selective excitation and multi-echo chemical shift encoding for imaging of hyperpolarized [1- 13C]pyruvate. J Magn Reson 2021; 325:106927. [PMID: 33607386 PMCID: PMC8009829 DOI: 10.1016/j.jmr.2021.106927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/31/2020] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Imaging methods for hyperpolarized (HP) 13C agents must sample the evolution of signal from multiple agents with distinct chemical shifts within a very brief timeframe (typically < 1 min), which is challenging using conventional imaging methods. In this work, we compare two of the most commonly used HP spectroscopic imaging methods, spectral-spatial selective excitation and multi-echo chemical shift encoding (CSE, also referred to as IDEAL), for a typical preclinical HP [1-13C]pyruvate imaging scan at 7 T. Both spectroscopic encoding techniques were implemented and validated in HP experiments imaging enzyme phantoms and the murine kidney. SNR performance of these two spectroscopic imaging approaches was compared in numerical simulations and phantom experiments using a single-shot flyback EPI readout for spatial encoding. With identical effective excitation angles, the SNR of images acquired with spectral-spatial excitations and CSE were found to be effectively equivalent.
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Affiliation(s)
- Keith A Michel
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States; Medical Physics Graduate Program, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Christopher M Walker
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States
| | - Stephen Y Lai
- Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - James A Bankson
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States; Medical Physics Graduate Program, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States.
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Shannon CE, Ragavan M, Palavicini JP, Fourcaudot M, Bakewell TM, Valdez IA, Ayala I, Jin ES, Madesh M, Han X, Merritt ME, Norton L. Insulin resistance is mechanistically linked to hepatic mitochondrial remodeling in non-alcoholic fatty liver disease. Mol Metab 2021; 45:101154. [PMID: 33359401 PMCID: PMC7811046 DOI: 10.1016/j.molmet.2020.101154] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/18/2020] [Accepted: 12/20/2020] [Indexed: 12/23/2022] Open
Abstract
OBJECTIVE Insulin resistance and altered hepatic mitochondrial function are central features of type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD), but the etiological role of these processes in disease progression remains unclear. Here we investigated the molecular links between insulin resistance, mitochondrial remodeling, and hepatic lipid accumulation. METHODS Hepatic insulin sensitivity, endogenous glucose production, and mitochondrial metabolic fluxes were determined in wild-type, obese (ob/ob) and pioglitazone-treatment obese mice using a combination of radiolabeled tracer and stable isotope NMR approaches. Mechanistic studies of pioglitazone action were performed in isolated primary hepatocytes, whilst molecular hepatic lipid species were profiled using shotgun lipidomics. RESULTS Livers from obese, insulin-resistant mice displayed augmented mitochondrial content and increased tricarboxylic acid cycle (TCA) cycle and pyruvate dehydrogenase (PDH) activities. Insulin sensitization with pioglitazone mitigated pyruvate-driven TCA cycle activity and PDH activation via both allosteric (intracellular pyruvate availability) and covalent (PDK4 and PDP2) mechanisms that were dependent on PPARγ activity in isolated primary hepatocytes. Improved mitochondrial function following pioglitazone treatment was entirely dissociated from changes in hepatic triglycerides, diacylglycerides, or fatty acids. Instead, we highlight a role for the mitochondrial phospholipid cardiolipin, which underwent pathological remodeling in livers from obese mice that was reversed by insulin sensitization. CONCLUSION Our findings identify targetable mitochondrial features of T2D and NAFLD and highlight the benefit of insulin sensitization in managing the clinical burden of obesity-associated disease.
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Affiliation(s)
- Chris E Shannon
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Juan Pablo Palavicini
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Marcel Fourcaudot
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Terry M Bakewell
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Ivan A Valdez
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Iriscilla Ayala
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Eunsook S Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Muniswamy Madesh
- Division of Nephrology, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA
| | - Xianlin Han
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA; Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA; Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Luke Norton
- Division of Diabetes, University of Texas Health Science Center and Texas Diabetes Institute, San Antonio, TX, USA.
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Mahar R, Zeng H, Giacalone A, Ragavan M, Mareci TH, Merritt ME. Deuterated water imaging of the rat brain following metabolism of [ 2 H 7 ]glucose. Magn Reson Med 2021; 85:3049-3059. [PMID: 33576535 DOI: 10.1002/mrm.28700] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 01/20/2023]
Abstract
PURPOSE To determine whether deuterated water (HDO) generated from the metabolism of [2 H7 ]glucose is a sensitive biomarker of cerebral glycolysis and oxidative flux. METHODS A bolus of [2 H7 ]glucose was injected through the tail vein at 1.95 g/kg into Sprague-Dawley rats. A 2 H surface coil was placed on top of the head to record 2 H spectra of the brain every 1.3 minutes to measure glucose uptake and metabolism to HDO, lactate, and glutamate/glutamine. A two-point Dixon method based on a gradient-echo sequence was used to reconstruct deuterated glucose and water (HDO) images selectively. RESULTS The background HDO signal could be detected and imaged before glucose injection. The 2 H NMR spectra showed arrival of [2 H7 ]glucose and its metabolism in a time-dependent manner. A ratio of the HDO to glutamate/glutamine resonances demonstrates a pseudo-steady state following injection, in which cerebral metabolism dominates wash-in of HDO generated by peripheral metabolism. Brain spectroscopy reveals that HDO generation is linear with lactate and glutamate/glutamine appearance in the appropriate pseudo-steady state window. Selective imaging of HDO and glucose is easily accomplished using a gradient-echo method. CONCLUSION Metabolic imaging of HDO, as a marker of glucose, lactate, and glutamate/glutamine metabolism, has been shown here for the first time. Cerebral glucose metabolism can be assessed efficiently using a standard gradient-echo sequence that provides superior in-plane resolution compared with CSI-based techniques.
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Affiliation(s)
- Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Huadong Zeng
- Advanced Magnetic Resonance Imaging and Spectroscopy Facility, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Anthony Giacalone
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Thomas H Mareci
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
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Chen C, Mahar R, Merritt ME, Denlinger DL, Hahn DA. ROS and hypoxia signaling regulate periodic metabolic arousal during insect dormancy to coordinate glucose, amino acid, and lipid metabolism. Proc Natl Acad Sci U S A 2021; 118:e2017603118. [PMID: 33372159 PMCID: PMC7817151 DOI: 10.1073/pnas.2017603118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Metabolic suppression is a hallmark of animal dormancy that promotes overall energy savings. Some diapausing insects and some mammalian hibernators have regular cyclic patterns of substantial metabolic depression alternating with periodic arousal where metabolic rates increase dramatically. Previous studies, largely in mammalian hibernators, have shown that periodic arousal is driven by an increase in aerobic mitochondrial metabolism and that many molecules related to energy metabolism fluctuate predictably across periodic arousal cycles. However, it is still not clear how these rapid metabolic shifts are regulated. We first found that diapausing flesh fly pupae primarily use anaerobic glycolysis during metabolic depression but engage in aerobic respiration through the tricarboxylic acid cycle during periodic arousal. Diapausing pupae also clear anaerobic by-products and regenerate many metabolic intermediates depleted in metabolic depression during arousal, consistent with patterns in mammalian hibernators. We found that decreased levels of reactive oxygen species (ROS) induced metabolic arousal and elevated ROS extended the duration of metabolic depression. Our data suggest ROS regulates the timing of metabolic arousal by changing the activity of two critical metabolic enzymes, pyruvate dehydrogenase and carnitine palmitoyltransferase I by modulating the levels of hypoxia inducible transcription factor (HIF) and phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK). Our study shows that ROS signaling regulates periodic arousal in our insect diapasue system, suggesting the possible importance ROS for regulating other types of of metabolic cycles in dormancy as well.
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Affiliation(s)
- Chao Chen
- Department of Entomology and Nematology, The University of Florida, Gainesville, FL 32611-0620;
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, The University of Florida, Gainesville, FL 32610-0245
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, The University of Florida, Gainesville, FL 32610-0245
| | - David L Denlinger
- Department of Entomology, 300 Aronoff Laboratory, The Ohio State University, Columbus, OH 43210;
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 300 Aronoff Laboratory, Columbus, OH 43210
| | - Daniel A Hahn
- Department of Entomology and Nematology, The University of Florida, Gainesville, FL 32611-0620;
- Genetics Institute, The University of Florida, Gainesville, FL 32610-3610
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Ragavan M, Li M, Giacalone AG, Wood CE, Keller-Wood M, Merritt ME. Application of Carbon-13 Isotopomer Analysis to Assess Perinatal Myocardial Glucose Metabolism in Sheep. Metabolites 2021; 11:33. [PMID: 33466367 PMCID: PMC7824843 DOI: 10.3390/metabo11010033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/16/2020] [Accepted: 01/01/2021] [Indexed: 11/16/2022] Open
Abstract
Ovine models of pregnancy have been used extensively to study maternal-fetal interactions and have provided considerable insight into nutrient transfer to the fetus. Ovine models have also been utilized to study congenital heart diseases. In this work, we demonstrate a comprehensive assessment of heart function and metabolism using a perinatal model of heart function with the addition of a [U-13C]glucose as tracer to study central energy metabolism. Using nuclear magnetic resonance spectroscopy, and metabolic modelling, we estimate myocardial citric acid cycle turnover (normalized for oxygen consumption), substrate selection, and anaplerotic fluxes. This methodology can be applied to studying acute and chronic effects of hormonal signaling in future studies.
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Affiliation(s)
- Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
| | - Mengchen Li
- Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA; (M.L.); (M.K.-W.)
| | - Anthony G. Giacalone
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
| | - Charles E. Wood
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32603, USA;
- Donald H Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32603, USA
| | - Maureen Keller-Wood
- Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA; (M.L.); (M.K.-W.)
- Donald H Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL 32603, USA
| | - Matthew E. Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32603, USA; (M.R.); (A.G.G.)
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von Morze C, Engelbach JA, Reed GD, Chen AP, Quirk JD, Blazey T, Mahar R, Malloy CR, Garbow JR, Merritt ME. 15 N-carnitine, a novel endogenous hyperpolarized MRI probe with long signal lifetime. Magn Reson Med 2020; 85:1814-1820. [PMID: 33179825 DOI: 10.1002/mrm.28578] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/05/2020] [Accepted: 10/09/2020] [Indexed: 12/22/2022]
Abstract
PURPOSE The purpose of this study was to investigate hyperpolarization and in vivo imaging of [15 N]carnitine, a novel endogenous MRI probe with long signal lifetime. METHODS L-[15 N]carnitine-d9 was hyperpolarized by the method of dynamic nuclear polarization followed by rapid dissolution. The T1 signal lifetimes were estimated in aqueous solution and in vivo following intravenous injection in rats, using a custom-built dual-tuned 15 N/1 H RF coil at 4.7 T. 15 N chemical shift imaging and 15 N fast spin-echo images of rat abdomen were acquired 3 minutes after [15 N]carnitine injection. RESULTS Estimated T1 times of [15 N]carnitine at 4.7 T were 210 seconds (in H2 O) and 160 seconds (in vivo), with an estimated polarization level of 10%. Remarkably, the [15 N]carnitine coherence was detectable in rat abdomen for 5 minutes after injection for the nonlocalized acquisition. No downstream metabolites were detected on localized or nonlocalized 15 N spectra. Diffuse liver enhancement was detected on 15 N fast spin-echo imaging 3 minutes after injection, with mean hepatic SNR of 18 ± 5 at a spatial resolution of 4 × 4 mm. CONCLUSION This study showed the feasibility of hyperpolarizing and imaging the biodistribution of HP [15 N]carnitine.
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Affiliation(s)
- Cornelius von Morze
- Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri, USA
| | - John A Engelbach
- Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri, USA
| | | | | | - James D Quirk
- Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri, USA
| | - Tyler Blazey
- Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri, USA
| | - Rohit Mahar
- Department of Biochemistry, University of Florida, Gainesville, Florida, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas, Southwestern, Dallas, Texas, USA
| | - Joel R Garbow
- Mallinckrodt Institute of Radiology, Washington University, St Louis, Missouri, USA
| | - Matthew E Merritt
- Department of Biochemistry, University of Florida, Gainesville, Florida, USA
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Muyyarikkandy MS, McLeod M, Maguire M, Mahar R, Kattapuram N, Zhang C, Surugihalli C, Muralidaran V, Vavilikolanu K, Mathews CE, Merritt ME, Sunny NE. Branched chain amino acids and carbohydrate restriction exacerbate ketogenesis and hepatic mitochondrial oxidative dysfunction during NAFLD. FASEB J 2020; 34:14832-14849. [PMID: 32918763 DOI: 10.1096/fj.202001495r] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/10/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022]
Abstract
Mitochondrial adaptation during non-alcoholic fatty liver disease (NAFLD) include remodeling of ketogenic flux and sustained tricarboxylic acid (TCA) cycle activity, which are concurrent to onset of oxidative stress. Over 70% of obese humans have NAFLD and ketogenic diets are common weight loss strategies. However, the effectiveness of ketogenic diets toward alleviating NAFLD remains unclear. We hypothesized that chronic ketogenesis will worsen metabolic dysfunction and oxidative stress during NAFLD. Mice (C57BL/6) were kept (for 16-wks) on either a low-fat, high-fat, or high-fat diet supplemented with 1.5X branched chain amino acids (BCAAs) by replacing carbohydrate calories (ketogenic). The ketogenic diet induced hepatic lipid oxidation and ketogenesis, and produced multifaceted changes in flux through the individual steps of the TCA cycle. Higher rates of hepatic oxidative fluxes fueled by the ketogenic diet paralleled lower rates of de novo lipogenesis. Interestingly, this metabolic remodeling did not improve insulin resistance, but induced fibrogenic genes and inflammation in the liver. Under a chronic "ketogenic environment," the hepatocyte diverted more acetyl-CoA away from lipogenesis toward ketogenesis and TCA cycle, a milieu which can hasten oxidative stress and inflammation. In summary, chronic exposure to ketogenic environment during obesity and NAFLD has the potential to aggravate hepatic mitochondrial dysfunction.
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Affiliation(s)
| | - Marc McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Meghan Maguire
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nathan Kattapuram
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Christine Zhang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Chaitra Surugihalli
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Vaishna Muralidaran
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Kruthi Vavilikolanu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Clayton E Mathews
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nishanth E Sunny
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
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36
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Morla L, Shore O, Lynch IJ, Merritt ME, Wingo CS. A noninvasive method to study the evolution of extracellular fluid volume in mice using time-domain nuclear magnetic resonance. Am J Physiol Renal Physiol 2020; 319:F115-F124. [PMID: 32475134 DOI: 10.1152/ajprenal.00377.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Maintaining water homeostasis is fundamental for cellular function. Many diseases and drugs affect water balance and plasma osmolality. Water homeostasis studies in small animals require the use of invasive or terminal methods that make intracellular fluid volume and extracellular fluid volume (ECF) monitoring over time stressful and time consuming. We examined the feasibility of monitoring mouse ECF by a noninvasive method using time-domain nuclear magnetic resonance (TD-NMR). This technique allows differentiation of protons in a liquid environment (free fluid) from protons in soft tissues containing a majority of either small molecules (lean) or large molecules (fat). Moreover, this apparatus enables rapid, noninvasive, and repeated measurements on the same animal. We assessed the feasibility of coupling TD-NMR analysis to a longitudinal metabolic cage study by monitoring mice daily. We determined the effect of 24-h water deprivation on mouse body parameters and detected a sequential and overlapping decrease in free fluid and lean mass during water deprivation. Finally, we studied the effect of mineralocorticoids that are known to induce a transient increase in ECF but for which no direct measurements have been performed in mice. We showed, for the first time, that mineralocorticoids induced a transient ~15% increase in free fluid in conscious mice. TD-NMR is, therefore, the first method to allow direct measurement of discrete changes in ECF in conscious small animals. This method allows analysis of kinetic changes to stimuli before investigating with terminal methods and will allow further understanding of fluid disorders.
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Affiliation(s)
- Luciana Morla
- Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France.,Centre National de la Recherche Scientifique, ERL 8228, Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Oliver Shore
- North Florida/South Georgia Veterans Health System, Gainesville, Florida.,Department of Medicine, University of Florida, Gainesville, Florida
| | - I Jeanette Lynch
- North Florida/South Georgia Veterans Health System, Gainesville, Florida.,Department of Medicine, University of Florida, Gainesville, Florida
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida
| | - Charles S Wingo
- North Florida/South Georgia Veterans Health System, Gainesville, Florida.,Department of Medicine, University of Florida, Gainesville, Florida
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Abstract
Increased glucose uptake and aerobic glycolysis are striking features of many cancers. These features have led to many techniques for screening and diagnosis, but many are expensive, less feasible or have harmful side-effects. Here, we report a sensitive 1H/2H NMR method to measure the kinetics of lactate isotopomer and HDO production using a deuterated tracer. To test this hypothesis, HUH-7 hepatocellular carcinoma and AML12 normal hepatocytes were incubated with [2H7]glucose. 1H/2H NMR data were recorded for cell media as a function of incubation time. The efflux rate of lactate-CH3, lactate-CH2D and lactate-CHD2 was calculated as 0.0033, 0.0071, and 0.0.012 µmol/106cells/min respectively. Differential production of lactate isotopomers was due to deuterium loss during glycolysis. Glucose uptake and HDO production by HUH-7 cells showed a strong correlation, indicating that monitoring the HDO production could be a diagnostic feature in cancers. Deuterium mass balance of [2H7]glucose uptake to 2H-lactate and HDO production is quantitatively matched, suggesting increasing HDO signal could be used to diagnose Warburg (cancer) metabolism. Measuring the kinetics of lactate isotopomer and HDO production by 1H and 2H MR respectively are highly sensitive. Increased T1 of 2H-lactate isotopomers indicates inversion/saturation recovery methods may be a simple means of generating metabolism-based contrast.
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Affiliation(s)
- Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Patrick L Donabedian
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
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38
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Giacalone AG, Ragavan M, Downes D, McLeod M, Carter A, Michel K, Bankson JA, Merritt ME. Real Time Direct Detection of β – hydroxybutyrate Production in Perfused Mice Livers Using HP DHA. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.09768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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McLeod MA, Ravagan M, Downes D, Merritt ME. Characterization Of Liver Metabolism By NMR‐Guided GC‐MS Methodology. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.09759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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von Morze C, Merritt ME. Cancer in the crosshairs: targeting cancer metabolism with hyperpolarized carbon-13 MRI technology. NMR Biomed 2019; 32:e3937. [PMID: 29870085 PMCID: PMC6281789 DOI: 10.1002/nbm.3937] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/03/2018] [Accepted: 04/07/2018] [Indexed: 05/07/2023]
Abstract
Magnetic resonance (MR)-based hyperpolarized (HP) 13 C metabolic imaging is under active pursuit as a new clinical diagnostic method for cancer detection, grading, and monitoring of therapeutic response. Following the tremendous success of metabolic imaging by positron emission tomography, which already plays major roles in clinical oncology, the added value of HP 13 C MRI is emerging. Aberrant glycolysis and central carbon metabolism is a hallmark of many forms of cancer. The chemical transformations associated with these pathways produce metabolites ranging in general from three to six carbons, and are dependent on the redox state and energy charge of the tissue. The significant changes in chemistry associated with flux through these pathways imply that HP imaging can take advantage of the underlying chemical shift information encoded into an MR experiment to produce images of the injected substrate as well as its metabolites. However, imaging of HP metabolites poses unique constraints on pulse sequence design related to detection of X-nuclei, decay of the HP magnetization due to T1 , and the consumption of HP signal by the inspection pulses. Advancements in the field continue to depend critically on customization of MRI systems and pulse sequences for optimized detection of HP 13 C signals, focused largely on extracting the maximum amount of information during the short lifetime of the HP magnetization. From a clinical perspective, the success of HP 13 C MRI of cancer will largely depend upon the utility of HP pyruvate for the detection of lactate pools associated with the Warburg effect, though several other agents are also under investigation, with novel agents continually being formulated. In this review, the salient aspects of HP 13 C imaging will be highlighted, with an emphasis on both technological challenges and the biochemical aspects of HP experimental design.
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Affiliation(s)
- Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
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41
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Chen H, Humes ST, Robinson SE, Loeb JC, Sabaraya IV, Saleh NB, Khattri RB, Merritt ME, Martyniuk CJ, Lednicky JA, Sabo-Attwood T. Single-walled carbon nanotubes repress viral-induced defense pathways through oxidative stress. Nanotoxicology 2019; 13:1176-1196. [PMID: 31328592 DOI: 10.1080/17435390.2019.1645903] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Exposure of lung cells in vitro or mice to single-walled carbon nanotubes (SWCNTs) directly to the respiratory tract leads to a reduced host anti-viral immune response to infection with influenza A virus H1N1 (IAV), resulting in significant increases in viral titers. This suggests that unintended exposure to nanotubes via inhalation may increase susceptibility to notorious respiratory viruses that carry a high social and economic burden globally. However, the molecular mechanisms that contribute to viral susceptibility have not been elucidated. In the present study, we identified the retinoic acid-induced gene I (RIG-I) like receptors (RLRs)/mitochondrial antiviral signaling (MAVS) pathway as a target of SWCNT-induced oxidative stress in small airway epithelial cells (SAEC) that contribute to significantly enhanced influenza viral titers. Exposure of SAEC to SWCNTs increases viral titers while repressing several aspects of the RLR pathway, including mRNA expression of key genes (e.g. IFITs, RIG-I, MDA5, IFNβ1, CCL5). SWCNTs also reduce mitochondrial membrane potential without altering oxygen consumption rates. Our findings also indicate that SWCNTs can impair formation of MAVS prion-like aggregates, which is known to impede downstream activation of the RLR pathway and hence the transcriptional production of interferon-regulated anti-viral genes and cytokines. Furthermore, application of the antioxidant NAC alleviates inhibition of gene expression levels by SWCNTs, as well as MAVS signalosome formation, and increased viral titers. These data provide evidence of targeted impairment of anti-viral signaling networks that are vital to immune defense mechanisms in lung cells, contributing to increased susceptibility to IAV infections by SWCNTs.
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Affiliation(s)
- Hao Chen
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
| | - Sara T Humes
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
| | - Sarah E Robinson
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
| | - Julia C Loeb
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
| | - Indu V Sabaraya
- Department of Department of Civil, Architectural, and Environmental Engineering, University of Texas Austin , Austin , TX , USA
| | - Navid B Saleh
- Department of Department of Civil, Architectural, and Environmental Engineering, University of Texas Austin , Austin , TX , USA
| | - Ram B Khattri
- Department of Biochemistry & Molecular Biology, University of Florida , Gainesville , FL , USA
| | - Matthew E Merritt
- Department of Biochemistry & Molecular Biology, University of Florida , Gainesville , FL , USA
| | - Christopher J Martyniuk
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida , Gainesville , FL , USA
| | - John A Lednicky
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
| | - Tara Sabo-Attwood
- Department of Environmental and Global Health, Center for Environmental and Human Toxicology and Emerging Pathogens Institute, University of Florida , Gainesville , FL , USA
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42
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Osis G, Webster KL, Harris AN, Lee HW, Chen C, Fang L, Romero MF, Khattri RB, Merritt ME, Verlander JW, Weiner ID. Regulation of renal NaDC1 expression and citrate excretion by NBCe1-A. Am J Physiol Renal Physiol 2019; 317:F489-F501. [PMID: 31188034 PMCID: PMC6732450 DOI: 10.1152/ajprenal.00015.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/20/2019] [Accepted: 06/07/2019] [Indexed: 11/22/2022] Open
Abstract
Citrate is critical for acid-base homeostasis and to prevent calcium nephrolithiasis. Both metabolic acidosis and hypokalemia decrease citrate excretion and increase expression of Na+-dicarboxylate cotransporter 1 (NaDC1; SLC13A2), the primary protein involved in citrate reabsorption. However, the mechanisms transducing extracellular signals and mediating these responses are incompletely understood. The purpose of the present study was to determine the role of the Na+-coupled electrogenic bicarbonate cotransporter (NBCe1) A variant (NBCe1-A) in citrate metabolism under basal conditions and in response to acid loading and hypokalemia. NBCe1-A deletion increased citrate excretion and decreased NaDC1 expression in the proximal convoluted tubules (PCT) and proximal straight tubules (PST) in the medullary ray (PST-MR) but not in the PST in the outer medulla (PST-OM). Acid loading wild-type (WT) mice decreased citrate excretion. NaDC1 expression increased only in the PCT and PST-MR and not in the PST-MR. In NBCe1-A knockout (KO) mice, the acid loading change in citrate excretion was unaffected, changes in PCT NaDC1 expression were blocked, and there was an adaptive increase in PST-MR. Hypokalemia in WT mice decreased citrate excretion; NaDC1 expression increased only in the PCT and PST-MR. NBCe1-A KO blocked both the citrate and NaDC1 changes. We conclude that 1) adaptive changes in NaDC1 expression in response to metabolic acidosis and hypokalemia occur specifically in the PCT and PST-MR, i.e., in cortical proximal tubule segments; 2) NBCe1-A is necessary for normal basal, metabolic acidosis and hypokalemia-stimulated citrate metabolism and does so by regulating NaDC1 expression in cortical proximal tubule segments; and 3) adaptive increases in PST-OM NaDC1 expression occur in NBCe1-A KO mice in response to acid loading that do not occur in WT mice.
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Affiliation(s)
- Gunars Osis
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Kierstin L Webster
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Autumn N Harris
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Department of Small Animal Clinical Sciences, University of Florida College of Veterinary Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Chao Chen
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Lijuan Fang
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Ram B Khattri
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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Turer A, Altamirano F, Schiattarella GG, May H, Gillette TG, Malloy CR, Merritt ME. Remodeling of substrate consumption in the murine sTAC model of heart failure. J Mol Cell Cardiol 2019; 134:144-153. [PMID: 31340162 DOI: 10.1016/j.yjmcc.2019.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 07/01/2019] [Accepted: 07/17/2019] [Indexed: 01/07/2023]
Abstract
BACKGROUND Energy metabolism and substrate selection are key aspects of correct myocardial mechanical function. Myocardial preference for oxidizable substrates changes in both hypertrophy and in overt failure. Previous work has shown that glucose oxidation is upregulated in overpressure hypertrophy, but its fate in overt failure is less clear. Anaplerotic flux of pyruvate into the tricarboxylic acid cycle (TCA) has been posited as a secondary fate of glycolysis, aside from pyruvate oxidation or lactate production. METHODS AND RESULTS A model of heart failure that emulates both valvular and hypertensive heart disease, the severe transaortic constriction (sTAC) mouse, was assayed for changes in substrate preference using metabolomic and carbon-13 flux measurements. Quantitative measures of O2 consumption in the Langendorff perfused mouse heart were paired with 13C isotopomer analysis to assess TCA cycle turnover. Since the heart accommodates oxidation of all physiological energy sources, the utilization of carbohydrates, fatty acids, and ketones were measured simultaneously using a triple-tracer NMR method. The fractional contribution of glucose to acetyl-CoA production was upregulated in heart failure, while other sources were not significantly different. A model that includes both pyruvate carboxylation and anaplerosis through succinyl-CoA produced superior fits to the data compared to a model using only pyruvate carboxylation. In the sTAC heart, anaplerosis through succinyl-CoA is elevated, while pyruvate carboxylation was not. Metabolomic data showed depleted TCA cycle intermediate pool sizes versus the control, in agreement with previous results. CONCLUSION In the sTAC heart failure model, the glucose contribution to acetyl-CoA production was significantly higher, with compensatory changes in fatty acid and ketone oxidation not reaching a significant level. Anaplerosis through succinyl-CoA is also upregulated, and is likely used to preserve TCA cycle intermediate pool sizes. The triple tracer method used here is new, and can be used to assess sources of acetyl-CoA production in any oxidative tissue.
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Affiliation(s)
- Aslan Turer
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, United States of America.
| | - Francisco Altamirano
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, United States of America.
| | - Gabriele G Schiattarella
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, United States of America.
| | - Herman May
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, United States of America.
| | - Thomas G Gillette
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, United States of America.
| | - Craig R Malloy
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX 75390, United States of America; Department of Radiology, UT Southwestern Medical Center, Dallas, TX 75390, United States of America; VA North Texas Healthcare System, Lancaster, TX, United States of America.
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610-0245, United States of America.
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44
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Gu Z, Liu Y, Cai F, Patrick M, Zmajkovic J, Cao H, Zhang Y, Tasdogan A, Chen M, Qi L, Liu X, Li K, Lyu J, Dickerson KE, Chen W, Ni M, Merritt ME, Morrison SJ, Skoda RC, DeBerardinis RJ, Xu J. Loss of EZH2 Reprograms BCAA Metabolism to Drive Leukemic Transformation. Cancer Discov 2019; 9:1228-1247. [PMID: 31189531 DOI: 10.1158/2159-8290.cd-19-0152] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 05/16/2019] [Accepted: 06/07/2019] [Indexed: 01/21/2023]
Abstract
Epigenetic gene regulation and metabolism are highly intertwined, yet little is known about whether altered epigenetics influence cellular metabolism during cancer progression. Here, we show that EZH2 and NRASG12D mutations cooperatively induce progression of myeloproliferative neoplasms to highly penetrant, transplantable, and lethal myeloid leukemias in mice. EZH1, an EZH2 homolog, is indispensable for EZH2-deficient leukemia-initiating cells and constitutes an epigenetic vulnerability. BCAT1, which catalyzes the reversible transamination of branched-chain amino acids (BCAA), is repressed by EZH2 in normal hematopoiesis and aberrantly activated in EZH2-deficient myeloid neoplasms in mice and humans. BCAT1 reactivation cooperates with NRASG12D to sustain intracellular BCAA pools, resulting in enhanced mTOR signaling in EZH2-deficient leukemia cells. Genetic and pharmacologic inhibition of BCAT1 selectively impairs EZH2-deficient leukemia-initiating cells and constitutes a metabolic vulnerability. Hence, epigenetic alterations rewire intracellular metabolism during leukemic transformation, causing epigenetic and metabolic vulnerabilities in cancer-initiating cells. SIGNIFICANCE: EZH2 inactivation and oncogenic NRAS cooperate to induce leukemic transformation of myeloproliferative neoplasms by activating BCAT1 to enhance BCAA metabolism and mTOR signaling. We uncover a mechanism by which epigenetic alterations rewire metabolism during cancer progression, causing epigenetic and metabolic liabilities in cancer-initiating cells that may be exploited as potential therapeutics.See related commentary by Li and Melnick, p. 1158.This article is highlighted in the In This Issue feature, p. 1143.
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Affiliation(s)
- Zhimin Gu
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Yuxuan Liu
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Feng Cai
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - McKenzie Patrick
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jakub Zmajkovic
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland
| | - Hui Cao
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Yuannyu Zhang
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Alpaslan Tasdogan
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mingyi Chen
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Le Qi
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Xin Liu
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kailong Li
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Junhua Lyu
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kathryn E Dickerson
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Weina Chen
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Min Ni
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Miami, Florida
| | - Sean J Morrison
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Radek C Skoda
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jian Xu
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, Texas. .,Department of Pediatrics, Harold C. Simmons Comprehensive Cancer Center, and Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas
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45
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Kirpich A, Ragavan M, Bankson JA, McIntyre LM, Merritt ME. Kinetic Analysis of Hepatic Metabolism Using Hyperpolarized Dihydroxyacetone. J Chem Inf Model 2019; 59:605-614. [PMID: 30602117 DOI: 10.1021/acs.jcim.8b00745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hyperpolarized carbon-13 magnetic resonance (HP-MR) is a new metabolic imaging method the does not use ionizing radiation. Due to the inherent chemical specificity of MR, not only tracer uptake but also downstream metabolism of the agent is detected in a straightforward manner. HP [2-13C] dihydroxyacetone (DHA) is a promising new agent that directly interrogates hepatic glucose metabolism. DHA has three metabolic fates in the liver: glucose production, glycerol production and potential inclusion into triglycerides, and oxidation in the tricarboxylic acid cycle. Each pathway is regulated by flux through multiple enzymes. Using Duhamel's formula, the kinetics of DHA metabolism is modeled, resulting in estimates of specific reaction rate constants. The multiple enzymatic steps that control DHA metabolism make more simplified methods for extracting kinetic data less than satisfactory. The described modeling paradigm effectively identifies changes in metabolism between gluconeogenic and glycogenolytic models of hepatic function.
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Affiliation(s)
- Alexander Kirpich
- Department of Biology , University of Florida , Gainesville , Florida 32611 , United States.,Informatics Institute , University of Florida , Gainesville , Florida 32611 , United States.,Southeast Center for Integrated Metabolomics , University of Florida , Gainesville , Florida 32611 , United States
| | - Mukundan Ragavan
- Department of Biochemistry and Molecular Biology , University of Florida , Gainesville , Florida 32611 , United States
| | - James A Bankson
- Department of Imaging Physics , The University of Texas MD Anderson Cancer Center , Houston , Texas 77030 , United States.,The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences , Houston , Texas 77030 , United States
| | - Lauren M McIntyre
- Southeast Center for Integrated Metabolomics , University of Florida , Gainesville , Florida 32611 , United States.,Department of Molecular Genetics and Microbiology , University of Florida , Gainesville , Florida 32611 , United States
| | - Matthew E Merritt
- Southeast Center for Integrated Metabolomics , University of Florida , Gainesville , Florida 32611 , United States.,Department of Biochemistry and Molecular Biology , University of Florida , Gainesville , Florida 32611 , United States
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46
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Kurhanewicz J, Vigneron DB, Ardenkjaer-Larsen JH, Bankson JA, Brindle K, Cunningham CH, Gallagher FA, Keshari KR, Kjaer A, Laustsen C, Mankoff DA, Merritt ME, Nelson SJ, Pauly JM, Lee P, Ronen S, Tyler DJ, Rajan SS, Spielman DM, Wald L, Zhang X, Malloy CR, Rizi R. Hyperpolarized 13C MRI: Path to Clinical Translation in Oncology. Neoplasia 2019; 21:1-16. [PMID: 30472500 PMCID: PMC6260457 DOI: 10.1016/j.neo.2018.09.006] [Citation(s) in RCA: 278] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/27/2018] [Accepted: 09/27/2018] [Indexed: 12/22/2022]
Abstract
This white paper discusses prospects for advancing hyperpolarization technology to better understand cancer metabolism, identify current obstacles to HP (hyperpolarized) 13C magnetic resonance imaging's (MRI's) widespread clinical use, and provide recommendations for overcoming them. Since the publication of the first NIH white paper on hyperpolarized 13C MRI in 2011, preclinical studies involving [1-13C]pyruvate as well a number of other 13C labeled metabolic substrates have demonstrated this technology's capacity to provide unique metabolic information. A dose-ranging study of HP [1-13C]pyruvate in patients with prostate cancer established safety and feasibility of this technique. Additional studies are ongoing in prostate, brain, breast, liver, cervical, and ovarian cancer. Technology for generating and delivering hyperpolarized agents has evolved, and new MR data acquisition sequences and improved MRI hardware have been developed. It will be important to continue investigation and development of existing and new probes in animal models. Improved polarization technology, efficient radiofrequency coils, and reliable pulse sequences are all important objectives to enable exploration of the technology in healthy control subjects and patient populations. It will be critical to determine how HP 13C MRI might fill existing needs in current clinical research and practice, and complement existing metabolic imaging modalities. Financial sponsorship and integration of academia, industry, and government efforts will be important factors in translating the technology for clinical research in oncology. This white paper is intended to provide recommendations with this goal in mind.
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Affiliation(s)
- John Kurhanewicz
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
| | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | | | - James A Bankson
- Department of Imaging Physics, MD Anderson Medical Center, Houston, TX, USA
| | - Kevin Brindle
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | | | - Kayvan R Keshari
- Department of Radiology, Memorial Sloan Kettering Cancer Center, NY, New York, USA
| | - Andreas Kjaer
- Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, Denmark
| | | | - David A Mankoff
- Department of Radiology, University of Pennsylvania, PA, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Sarah J Nelson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - John M Pauly
- Department of Electric Engineering, Stanford University, USA
| | - Philips Lee
- Functional Metabolism Group, Singapore Biomedical Consortium, Agency for Science, Technology and Research, Singapore
| | - Sabrina Ronen
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - Damian J Tyler
- Department of Biomedical Science, University of Oxford, Oxford, UK
| | - Sunder S Rajan
- Center for Devices and Radiological Health (CDRH), FDA, White Oak, MD, USA
| | - Daniel M Spielman
- Departments of Radiology and Electric Engineering, Stanford University, USA
| | - Lawrence Wald
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Xiaoliang Zhang
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Rahim Rizi
- Department of Radiology, University of Pennsylvania, PA, USA
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47
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Abstract
Polarization transfer from unpaired electron radicals to nuclear spins at low-temperature is achieved using microwave irradiation by a process broadly termed dynamic nuclear polarization (DNP). The resulting signal enhancement can easily exceed factors of 104 when paired with cryogenic cooling of the sample. Dissolution-DNP couples low temperature polarization methods with a rapid dissolution step, resulting in a highly polarized solution that can be used for metabolically sensitive magnetic resonance imaging (MRI). Hyperpolarized [1-13C]pyruvate is a powerful metabolic imaging agent for investigation of in vitro and in vivo cellular metabolism by means of NMR spectroscopy and MRI. Radicals (trityl OX063 and BDPA) with narrower EPR linewidths typically produce higher nuclear polarizations when carbon-13 is the target nucleus. Increased solid-state polarization is observed when narrow line radicals are doped with lanthanide ions such as Gd3+, Ho3+, Dy3+, and Tb3+. Earlier results have demonstrated an incongruence between DNP experiments with trityl and BDPA, where the optimal concentrations for polarization transfer are disparate despite similar electron spin resonance linewidths. Here, the effects of Ho-DOTA on the solid-state polarization of [1-13C]pyruvic acid were compared for 3.35 T (1.4 K) and 5 T (1.2 K) systems using BDPA as a radical. Multiple concentrations of BDPA were doped with variable concentrations of Ho-DOTA (0, 0.2, 0.5, 1, and 2 mM), and dissolved in 1 : 1 (v/v) of [1-13C] pyruvic acid/sulfolane mixture. Our results reveal that addition of small amounts of Ho-DOTA in the sample preparation increases the solid-state polarization for [1-13C] pyruvic acid, with the optimum Ho-DOTA concentration of 0.2 mM. Without Ho-DOTA doping, the optimum BDPA concentration found for 3.35 T (1.4 K) is 40 mM, and for 5 T (1.2 K) system it is about 60 mM. In both systems, inclusion of Ho-DOTA in the 13C DNP sample leads to a change in the breadth (ΔDNP) of the extrema between the P(+) and P(-) frequencies in microwave spectra. At no combination of BDPA and Ho3+ did polarizations reach those achievable with trityl. Simplified analysis of increased polarization as a function of decreased electron T1e used to explain results in trityl are insufficient to describe DNP with BDPA.
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Affiliation(s)
- Ram B Khattri
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, USA.
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48
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von Morze C, Reed GD, Larson PE, Mammoli D, Chen AP, Tropp J, Van Criekinge M, Ohliger MA, Kurhanewicz J, Vigneron DB, Merritt ME. In vivo hyperpolarization transfer in a clinical MRI scanner. Magn Reson Med 2018; 80:480-487. [PMID: 29488244 PMCID: PMC5910192 DOI: 10.1002/mrm.27154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 01/08/2018] [Accepted: 02/05/2018] [Indexed: 12/20/2022]
Abstract
PURPOSE The purpose of this study was to investigate the feasibility of in vivo 13 C->1 H hyperpolarization transfer, which has significant potential advantages for detecting the distribution and metabolism of hyperpolarized 13 C probes in a clinical MRI scanner. METHODS A standalone pulsed 13 C RF transmit channel was developed for operation in conjunction with the standard 1 H channel of a clinical 3T MRI scanner. Pulse sequences for 13 C power calibration and polarization transfer were programmed on the external hardware and integrated with a customized water-suppressed 1 H MRS acquisition running in parallel on the scanner. The newly developed RF system was tested in both phantom and in vivo polarization transfer experiments in 1 JCH -coupled systems: phantom experiments in thermally polarized and hyperpolarized [2-13 C]glycerol, and 1 H detection of [2-13 C]lactate generated from hyperpolarized [2-13 C]pyruvate in rat liver in vivo. RESULTS Operation of the custom pulsed 13 C RF channel resulted in effective 13 C->1 H hyperpolarization transfer, as confirmed by the characteristic antiphase appearance of 1 H-detected, 1 JCH -coupled doublets. In conjunction with a pulse sequence providing 190-fold water suppression in vivo, 1 H detection of hyperpolarized [2-13 C]lactate generated in vivo was achieved in a rat liver slice. CONCLUSION The results show clear feasibility for effective 13 C->1 H hyperpolarization transfer in a clinical MRI scanner with customized heteronuclear RF system.
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Affiliation(s)
- Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | | | - Peder E. Larson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | - Daniele Mammoli
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | | | | | - Mark Van Criekinge
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | - Michael A. Ohliger
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | - John Kurhanewicz
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco
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49
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Wu CY, Satapati S, Gui W, Wynn RM, Sharma G, Lou M, Qi X, Burgess SC, Malloy C, Khemtong C, Sherry AD, Chuang DT, Merritt ME. A novel inhibitor of pyruvate dehydrogenase kinase stimulates myocardial carbohydrate oxidation in diet-induced obesity. J Biol Chem 2018; 293:9604-9613. [PMID: 29739849 DOI: 10.1074/jbc.ra118.002838] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/23/2018] [Indexed: 11/06/2022] Open
Abstract
The pyruvate dehydrogenase complex (PDC) is a key control point of energy metabolism and is subject to regulation by multiple mechanisms, including posttranslational phosphorylation by pyruvate dehydrogenase kinase (PDK). Pharmacological modulation of PDC activity could provide a new treatment for diabetic cardiomyopathy, as dysregulated substrate selection is concomitant with decreased heart function. Dichloroacetate (DCA), a classic PDK inhibitor, has been used to treat diabetic cardiomyopathy, but the lack of specificity and side effects of DCA indicate a more specific inhibitor of PDK is needed. This study was designed to determine the effects of a novel and highly selective PDK inhibitor, 2((2,4-dihydroxyphenyl)sulfonyl) isoindoline-4,6-diol (designated PS10), on pyruvate oxidation in diet-induced obese (DIO) mouse hearts compared with DCA-treated hearts. Four groups of mice were studied: lean control, DIO, DIO + DCA, and DIO + PS10. Both DCA and PS10 improved glucose tolerance in the intact animal. Pyruvate metabolism was studied in perfused hearts supplied with physiological mixtures of long chain fatty acids, lactate, and pyruvate. Analysis was performed using conventional 1H and 13C isotopomer methods in combination with hyperpolarized [1-13C]pyruvate in the same hearts. PS10 and DCA both stimulated flux through PDC as measured by the appearance of hyperpolarized [13C]bicarbonate. DCA but not PS10 increased hyperpolarized [1-13C]lactate production. Total carbohydrate oxidation was reduced in DIO mouse hearts but increased by DCA and PS10, the latter doing so without increasing lactate production. The present results suggest that PS10 is a more suitable PDK inhibitor for treatment of diabetic cardiomyopathy.
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Affiliation(s)
- Cheng-Yang Wu
- From the Department of Biochemistry.,Advanced Imaging Research Center
| | | | | | - R Max Wynn
- From the Department of Biochemistry.,Department of Internal Medicine, and
| | | | - Mingliang Lou
- Chemistry Center, National Institute of Biological Science, Beijing 102206, China, and.,Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Xiangbing Qi
- Chemistry Center, National Institute of Biological Science, Beijing 102206, China, and.,Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
| | | | - Craig Malloy
- Advanced Imaging Research Center.,Department of Internal Medicine, and.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Chalermchai Khemtong
- Advanced Imaging Research Center.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - A Dean Sherry
- Advanced Imaging Research Center.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080
| | - David T Chuang
- From the Department of Biochemistry, .,Department of Internal Medicine, and
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610,
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50
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Bastiaansen JAM, Yoshihara HAI, Capozzi A, Schwitter J, Gruetter R, Merritt ME, Comment A. Probing cardiac metabolism by hyperpolarized 13C MR using an exclusively endogenous substrate mixture and photo-induced nonpersistent radicals. Magn Reson Med 2018; 79:2451-2459. [PMID: 29411415 DOI: 10.1002/mrm.27122] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/11/2018] [Accepted: 01/16/2018] [Indexed: 12/13/2022]
Abstract
PURPOSE To probe the cardiac metabolism of carbohydrates and short chain fatty acids simultaneously in vivo following the injection of a hyperpolarized 13 C-labeled substrate mixture prepared using photo-induced nonpersistent radicals. METHODS Droplets of mixed [1-13 C]pyruvic and [1-13 C]butyric acids were frozen into glassy beads in liquid nitrogen. Ethanol addition was investigated as a means to increase the polarization level. The beads were irradiated with ultraviolet light and the radical concentration was measured by ESR spectroscopy. Following dynamic nuclear polarization in a 7T polarizer, the beads were dissolved, and the radical-free hyperpolarized solution was rapidly transferred into an injection pump located inside a 9.4T scanner. The hyperpolarized solution was injected in healthy rats to measure cardiac metabolism in vivo. RESULTS Ultraviolet irradiation created nonpersistent radicals in a mixture containing 13 C-labeled pyruvic and butyric acids, and enabled the hyperpolarization of both substrates by dynamic nuclear polarization. Ethanol addition increased the radical concentration from 16 to 26 mM. Liquid-state 13 C polarization was 3% inside the pump at the time of injection, and increased to 5% by addition of ethanol to the substrate mixture prior to ultraviolet irradiation. In the rat heart, the in vivo 13 C signals from lactate, alanine, bicarbonate, and acetylcarnitine were detected following the metabolism of the injected substrate mixture. CONCLUSION Copolarization of two different 13 C-labeled substrates and the detection of their myocardial metabolism in vivo was achieved without using persistent radicals. The absence of radicals in the solution containing the hyperpolarized 13 C-substrates may simplify the translation to clinical use, as no radical filtration is required prior to injection.
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Affiliation(s)
- Jessica A M Bastiaansen
- Department of Radiology, University Hospital Lausanne and University of Lausanne, Lausanne, Switzerland.,Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Hikari A I Yoshihara
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Division of Cardiology and Cardiac MR Center, University Hospital Lausanne, Lausanne, Switzerland
| | - Andrea Capozzi
- Department of Electrical Engineering, Technical University of Denmark, Copenhagen, Denmark
| | - Juerg Schwitter
- Division of Cardiology and Cardiac MR Center, University Hospital Lausanne, Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Arnaud Comment
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,General Electric Healthcare, Pollards Wood, Chalfont St Giles, Buckinghamshire, United Kingdom
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