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Bosso M, Haddad D, Al Madhoun A, Al-Mulla F. Targeting the Metabolic Paradigms in Cancer and Diabetes. Biomedicines 2024; 12:211. [PMID: 38255314 PMCID: PMC10813379 DOI: 10.3390/biomedicines12010211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/09/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Dysregulated metabolic dynamics are evident in both cancer and diabetes, with metabolic alterations representing a facet of the myriad changes observed in these conditions. This review delves into the commonalities in metabolism between cancer and type 2 diabetes (T2D), focusing specifically on the contrasting roles of oxidative phosphorylation (OXPHOS) and glycolysis as primary energy-generating pathways within cells. Building on earlier research, we explore how a shift towards one pathway over the other serves as a foundational aspect in the development of cancer and T2D. Unlike previous reviews, we posit that this shift may occur in seemingly opposing yet complementary directions, akin to the Yin and Yang concept. These metabolic fluctuations reveal an intricate network of underlying defective signaling pathways, orchestrating the pathogenesis and progression of each disease. The Warburg phenomenon, characterized by the prevalence of aerobic glycolysis over minimal to no OXPHOS, emerges as the predominant metabolic phenotype in cancer. Conversely, in T2D, the prevailing metabolic paradigm has traditionally been perceived in terms of discrete irregularities rather than an OXPHOS-to-glycolysis shift. Throughout T2D pathogenesis, OXPHOS remains consistently heightened due to chronic hyperglycemia or hyperinsulinemia. In advanced insulin resistance and T2D, the metabolic landscape becomes more complex, featuring differential tissue-specific alterations that affect OXPHOS. Recent findings suggest that addressing the metabolic imbalance in both cancer and diabetes could offer an effective treatment strategy. Numerous pharmaceutical and nutritional modalities exhibiting therapeutic effects in both conditions ultimately modulate the OXPHOS-glycolysis axis. Noteworthy nutritional adjuncts, such as alpha-lipoic acid, flavonoids, and glutamine, demonstrate the ability to reprogram metabolism, exerting anti-tumor and anti-diabetic effects. Similarly, pharmacological agents like metformin exhibit therapeutic efficacy in both T2D and cancer. This review discusses the molecular mechanisms underlying these metabolic shifts and explores promising therapeutic strategies aimed at reversing the metabolic imbalance in both disease scenarios.
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Affiliation(s)
- Mira Bosso
- Department of Pathology, Faculty of Medicine, Health Science Center, Kuwait University, Safat 13110, Kuwait
| | - Dania Haddad
- Department of Genetics and Bioinformatics, Dasman Diabetes Institute, Dasman 15462, Kuwait; (D.H.); (A.A.M.)
| | - Ashraf Al Madhoun
- Department of Genetics and Bioinformatics, Dasman Diabetes Institute, Dasman 15462, Kuwait; (D.H.); (A.A.M.)
- Department of Animal and Imaging Core Facilities, Dasman Diabetes Institute, Dasman 15462, Kuwait
| | - Fahd Al-Mulla
- Department of Pathology, Faculty of Medicine, Health Science Center, Kuwait University, Safat 13110, Kuwait
- Department of Genetics and Bioinformatics, Dasman Diabetes Institute, Dasman 15462, Kuwait; (D.H.); (A.A.M.)
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2
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Metabolic cycles and signals for insulin secretion. Cell Metab 2022; 34:947-968. [PMID: 35728586 PMCID: PMC9262871 DOI: 10.1016/j.cmet.2022.06.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 06/01/2022] [Accepted: 06/04/2022] [Indexed: 02/03/2023]
Abstract
In this review, we focus on recent developments in our understanding of nutrient-induced insulin secretion that challenge a key aspect of the "canonical" model, in which an oxidative phosphorylation-driven rise in ATP production closes KATP channels. We discuss the importance of intrinsic β cell metabolic oscillations; the phasic alignment of relevant metabolic cycles, shuttles, and shunts; and how their temporal and compartmental relationships align with the triggering phase or the secretory phase of pulsatile insulin secretion. Metabolic signaling components are assigned regulatory, effectory, and/or homeostatic roles vis-à-vis their contribution to glucose sensing, signal transmission, and resetting the system. Taken together, these functions provide a framework for understanding how allostery, anaplerosis, and oxidative metabolism are integrated into the oscillatory behavior of the secretory pathway. By incorporating these temporal as well as newly discovered spatial aspects of β cell metabolism, we propose a much-refined MitoCat-MitoOx model of the signaling process for the field to evaluate.
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3
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Abstract
The ability to maintain normoglycaemia, through glucose-sensitive insulin release, is a key aspect of postnatal beta cell function. However, terminally differentiated beta cell identity does not necessarily imply functional maturity. Beta cell maturation is therefore a continuation of beta cell development, albeit a process that occurs postnatally in mammals. Although many important features have been identified in the study of beta cell maturation, as of yet no unified mechanistic model of beta cell functional maturity exists. Here, we review recent findings about the underlying mechanisms of beta cell functional maturation. These findings include systemic hormonal and nutritional triggers that operate through energy-sensing machinery shifts within beta cells, resulting in primed metabolic states that allow for appropriate glucose trafficking and, ultimately, insulin release. We also draw attention to the expansive synergistic nature of these pathways and emphasise that beta cell maturation is dependent on overlapping regulatory and metabolic networks.
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Affiliation(s)
- Tom Barsby
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
| | - Timo Otonkoski
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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4
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Mohamed SA, Fernadez-Tajes J, Franks PW, Bennet L. GWAS in people of Middle Eastern descent reveals a locus protective of kidney function-a cross-sectional study. BMC Med 2022; 20:76. [PMID: 35227251 PMCID: PMC8886846 DOI: 10.1186/s12916-022-02267-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/18/2022] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Type 2 diabetes is one of the leading causes of chronic kidney failure, which increases globally and represents a significant threat to public health. People from the Middle East represent one of the largest immigrant groups in Europe today. Despite poor glucose regulation and high risk for early-onset insulin-deficient type 2 diabetes, they have better kidney function and lower rates of all-cause and cardiovascular-specific mortality compared with people of European ancestry. Here, we assessed the genetic basis of estimated glomerular filtration rate (eGFR) and other metabolic traits in people of Iraqi ancestry living in southern Sweden. METHODS Genome-wide association study (GWAS) analyses were performed in 1201 Iraqi-born residents of the city of Malmö for eGFR and ten other metabolic traits using linear mixed-models to account for family structure. RESULTS The strongest association signal was detected for eGFR in CST9 (rs13037490; P value = 2.4 × 10-13), a locus previously associated with cystatin C-based eGFR; importantly, the effect (major) allele here contrasts the effect (minor) allele in other populations, suggesting favorable selection at this locus. Additional novel genome-wide significant loci for eGFR (ERBB4), fasting glucose (CAMTA1, NDUFA10, TRIO, WWC1, TRAPPC9, SH3GL2, ABCC11), quantitative insulin-sensitivity check index (METTL16), and HbA1C (CAMTA1, ME1, PAK1, RORA) were identified. CONCLUSIONS The genetic effects discovered here may help explain why people from the Middle East have better kidney function than those of European descent. Genetic predisposition to preserved kidney function may also underlie the observed survival benefits in Middle Eastern immigrants with type 2 diabetes.
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Affiliation(s)
- Siham A Mohamed
- Lund University Diabetes Center, Lund University, Malmö, Sweden.,Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Juan Fernadez-Tajes
- Lund University Diabetes Center, Lund University, Malmö, Sweden.,Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Paul W Franks
- Lund University Diabetes Center, Lund University, Malmö, Sweden. .,Department of Clinical Sciences, Lund University, Malmö, Sweden.
| | - Louise Bennet
- Department of Clinical Sciences, Lund University, Malmö, Sweden. .,Clinical Research and Trial Center, Lund University Hospital, Lund, Sweden.
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5
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Fu A, van Rooyen L, Evans L, Armstrong N, Avizonis D, Kin T, Bird GH, Reddy A, Chouchani ET, Liesa-Roig M, Walensky LD, Shapiro AMJ, Danial NN. Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets. Cell Rep 2021; 37:110037. [PMID: 34818536 PMCID: PMC8720303 DOI: 10.1016/j.celrep.2021.110037] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 08/25/2021] [Accepted: 11/01/2021] [Indexed: 02/07/2023] Open
Abstract
Glucose metabolism modulates the islet β cell responses to diabetogenic stress, including inflammation. Here, we probed the metabolic mechanisms that underlie the protective effect of glucose in inflammation by interrogating the metabolite profiles of primary islets from human donors and identified de novo glutathione synthesis as a prominent glucose-driven pro-survival pathway. We find that pyruvate carboxylase is required for glutathione synthesis in islets and promotes their antioxidant capacity to counter inflammation and nitrosative stress. Loss- and gain-of-function studies indicate that pyruvate carboxylase is necessary and sufficient to mediate the metabolic input from glucose into glutathione synthesis and the oxidative stress response. Altered redox metabolism and cellular capacity to replenish glutathione pools are relevant in multiple pathologies beyond obesity and diabetes. Our findings reveal a direct interplay between glucose metabolism and glutathione biosynthesis via pyruvate carboxylase. This metabolic axis may also have implications in other settings where sustaining glutathione is essential.
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Affiliation(s)
- Accalia Fu
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Lara van Rooyen
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA
| | - Lindsay Evans
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA
| | - Nina Armstrong
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA
| | - Daina Avizonis
- Rosalind and Morris Goodman Cancer Institute, Metabolomics Innovation Resource, 1160 Pine Avenue, Montreal, QC H3A 1A3, Canada
| | - Tatsuya Kin
- Clinical Islet Transplant Program, Department of Surgery, 2000 College Plaza, University of Alberta, Edmonton, AB T6G 2C8, Canada
| | - Gregory H Bird
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Anita Reddy
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Edward T Chouchani
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Marc Liesa-Roig
- Department of Medicine, Endocrinology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Dr., Los Angeles, CA 90095, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Dr., Los Angeles, CA 90095, USA; Molecular Biology Institute, UCLA, 614 Charles E. Young Dr., Los Angeles, CA 90095, USA
| | - Loren D Walensky
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - A M James Shapiro
- Clinical Islet Transplant Program, Department of Surgery, 2000 College Plaza, University of Alberta, Edmonton, AB T6G 2C8, Canada
| | - Nika N Danial
- Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston 02115, MA, USA; Department of Medicine, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
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6
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Singh J, Suh EH, Sharma G, Chen J, Hackett EP, Wen X, Sherry AD, Khemtong C, Malloy CR, Park JM, Kovacs Z. 13C-Labeled Diethyl Ketoglutarate Derivatives as Hyperpolarized Probes of 2-Ketoglutarate Dehydrogenase Activity. ANALYSIS & SENSING 2021; 1:156-160. [PMID: 35669533 PMCID: PMC9165698 DOI: 10.1002/anse.202100021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Indexed: 11/11/2022]
Abstract
The TCA cycle is a central metabolic pathway for energy production and biosynthesis. A major control point of metabolic flux through the cycle is the decarboxylation of 2-ketoglutarate by the TCA cycle enzyme 2-ketoglutarate dehydrogenase (2-KGDH). In this project, we developed 13C labeled 2-ketoglutarate derivatives to monitor 2-KGDH activity in vivo. 13C NMR analysis of liver extracts revealed that uniformly 13C labeled 2-ketogutarate, in its cell permeable ester form, was rapidly taken up and hydrolyzed in liver and underwent extensive metabolism to produce labeled glutamate, succinate, lactate and other metabolites. Diethyl [1,2-13C2]-2-ketoglutarate was successfully polarized by dynamic nuclear polarization and within seconds after injection into rats, the probe produced hyperpolarized [13C]bicarbonate in the liver reflecting flux through the TCA cycle. These experiments demonstrate that this tracer offers the possibility of directly monitoring flux through 2-KGDH in vivo.
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Affiliation(s)
- Jaspal Singh
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Eul Hyun Suh
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Gaurav Sharma
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Jun Chen
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Edward P Hackett
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Xiaodong Wen
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Chalermchai Khemtong
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, FL and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Jae Mo Park
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
| | - Zoltan Kovacs
- Advanced Imaging Research Center, University of Texas South-western Medical Center, Dallas, TX
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Mondal DK, Pal DS, Abbasi M, Datta R. Functional partnership between carbonic anhydrase and malic enzyme in promoting gluconeogenesis in
Leishmania major. FEBS J 2021; 288:4129-4152. [DOI: 10.1111/febs.15720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/29/2020] [Accepted: 01/15/2021] [Indexed: 12/24/2022]
Affiliation(s)
- Dipon Kumar Mondal
- Department of Biological Sciences Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur India
| | - Dhiman Sankar Pal
- Department of Biological Sciences Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur India
| | - Mazharul Abbasi
- Department of Biological Sciences Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur India
| | - Rupak Datta
- Department of Biological Sciences Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur India
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8
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Xie N, Zhang L, Gao W, Huang C, Huber PE, Zhou X, Li C, Shen G, Zou B. NAD + metabolism: pathophysiologic mechanisms and therapeutic potential. Signal Transduct Target Ther 2020; 5:227. [PMID: 33028824 PMCID: PMC7539288 DOI: 10.1038/s41392-020-00311-7] [Citation(s) in RCA: 372] [Impact Index Per Article: 93.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/04/2020] [Accepted: 08/20/2020] [Indexed: 02/06/2023] Open
Abstract
Nicotinamide adenine dinucleotide (NAD+) and its metabolites function as critical regulators to maintain physiologic processes, enabling the plastic cells to adapt to environmental changes including nutrient perturbation, genotoxic factors, circadian disorder, infection, inflammation and xenobiotics. These effects are mainly achieved by the driving effect of NAD+ on metabolic pathways as enzyme cofactors transferring hydrogen in oxidation-reduction reactions. Besides, multiple NAD+-dependent enzymes are involved in physiology either by post-synthesis chemical modification of DNA, RNA and proteins, or releasing second messenger cyclic ADP-ribose (cADPR) and NAADP+. Prolonged disequilibrium of NAD+ metabolism disturbs the physiological functions, resulting in diseases including metabolic diseases, cancer, aging and neurodegeneration disorder. In this review, we summarize recent advances in our understanding of the molecular mechanisms of NAD+-regulated physiological responses to stresses, the contribution of NAD+ deficiency to various diseases via manipulating cellular communication networks and the potential new avenues for therapeutic intervention.
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Affiliation(s)
- Na Xie
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China
| | - Lu Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China
| | - Wei Gao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China
| | - Canhua Huang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China
- School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan, 611137, China
| | - Peter Ernst Huber
- CCU Molecular and Radiation Oncology, German Cancer Research Center; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Xiaobo Zhou
- First Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Changlong Li
- West China School of Basic Medical Sciences & Forensic Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Guobo Shen
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China.
| | - Bingwen Zou
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China.
- CCU Molecular and Radiation Oncology, German Cancer Research Center; Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.
- Department of Thoracic Oncology and Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, China.
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Ethyl Pyruvate Increases Post-Ischemic Levels of Mitochondrial Energy Metabolites: A 13C-Labeled Cerebral Microdialysis Study. Metabolites 2020; 10:metabo10070287. [PMID: 32668656 PMCID: PMC7407637 DOI: 10.3390/metabo10070287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/09/2020] [Accepted: 07/10/2020] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial dysfunction after transient cerebral ischemia can be monitored by cerebral microdialysis (CMD) using changes in the lactate and pyruvate concentrations and ratio. Other metabolites associated with mitochondrial (dys)function are, e.g., tricyclic acid (TCA) and purine metabolites. Ethyl pyruvate (EP) is a putative neuroprotectant, supposedly targeting mitochondrial energy metabolism, but its effect on cerebral energy metabolism has never been described using microdialysis. In this study we monitored the metabolic effects of EP in the endothelin-1 (ET-1) rat model using perfusion with 13C-succinate and analysis of endogenous and 13C-labeled metabolites in the dialysates by liquid chromatography-mass spectrometry (LC-MS). Adult Sprague Dawley rats (n = 27 of which n = 11 were included in the study) were subjected to the microdialysis experiments. Microdialysis probes were perfused with 13C-labeled succinate (1 mM), and striatal dialysates were collected at 30 min intervals before induction of the insult, during intracerebral application of ET-1, and during intravenous treatment with either EP (40 mg/kg) or placebo, which was administered immediately after the insult. The rats were subjected to transient cerebral ischemia by unilateral microinjection of ET-1 in the piriform cortex, causing vasoconstriction of the medial cerebral artery. Monitoring was continued for 5 h after reperfusion, and levels of endogenous and 13C-labeled energy metabolites before and after ischemia-reperfusion were compared in EP-treated and control groups. Infarct volumes were assessed after 24 h. In both the EP-treated and placebo groups, ET-1-induced vasoconstriction resulted in a transient depression of interstitial glucose and elevation of lactate in the ipsilateral striatum. In the reperfusion phase, the concentrations of labeled malate, isocitrate, and lactate as well as endogenous xanthine were significantly higher in the EP-group than in the placebo-group: (mean ± SEM) labeled malate: 39.5% ± 14.9, p = 0.008; labeled isocitrate: 134.8% ± 67.9, p = 0.047; labeled lactate: 61% ± 22.0, p = 0.007; and endogenous xanthine: 93.9% ± 28.3, p = 0.0009. In the placebo group, significantly elevated levels of uridine were observed (mean ± SEM) 32.5% ± 12.7, p = 0.01. Infarct volumes were not significantly different between EP-treated and placebo groups, p = 0.4679. CMD labeled with 13C-succinate enabled detection of ischemic induction and EP treatment effects in the ET-1 rat model of transient focal cerebral ischemia. EP administered as a single intravenous bolus in the reperfusion-phase after transient cerebral ischemia increased de novo synthesis of several key intermediate energy metabolites (13C-malate, 13C-isocitrate, and endogenous xanthine). In summary, mitochondria process 13C-succinate more effectively after EP treatment.
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Yang J, Khan MAK, Zhang H, Zhang Y, Certik M, Garre V, Song Y. Mitochondrial Citrate Transport System in the Fungus Mucor circinelloides: Identification, Phylogenetic Analysis, and Expression Profiling During Growth and Lipid Accumulation. Curr Microbiol 2019; 77:220-231. [PMID: 31802201 DOI: 10.1007/s00284-019-01822-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/20/2019] [Indexed: 12/21/2022]
Abstract
The mitochondrial citrate transport system, composed of citrate and malate transporters (MTs), can regulate the citrate efflux from mitochondria to cytosol, and then citrate is cleaved into OAA and acetyl-CoA which can be used for fatty acid (FA) biosynthesis. However, in the fungus Mucor circinelloides the molecular mechanism of citrate efflux from the mitochondria by this system and its role in FA synthesis is unclear. In the present study, we have analyzed the genome of high lipid-producing strain WJ11 and the low lipid-producing strain CBS 277.49 to find the potential genes involving in this system. Five potential genes are present in the genome of WJ11. These genes encode one citrate transport protein (CT), one tricarboxylate carrier (TCT), one MT, and two 2-oxoglutarate:malate antiporters (SoDIT-a and SoDIT-b). However, the genome of CBS 277.49 contains the same set of genes, except for the presence of just one SoDIT. The proteins from WJ11 had similar properties as their counterparts in CBS 277.49. Moreover, phylogenetic analyses revealed the evolutionary relationship of these proteins and illuminated their typical motifs related to potential functions. Additionally, the expression of these genes was analyzed to predict the possible functions in lipid metabolism in M. circinelloides. This is the first study to report the in silico analysis of structures and functions of the mitochondrial citrate transport system in M. circinelloides. This work showed a new strategy for research for the selection of candidate genes for further detailed functional investigation of the mitochondrial citrate transport system in lipid accumulation.
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Affiliation(s)
- Junhuan Yang
- Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, Shandong, People's Republic of China
| | - Md Ahsanul Kabir Khan
- Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, Shandong, People's Republic of China
| | - Huaiyuan Zhang
- Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, Shandong, People's Republic of China
| | - Yao Zhang
- Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, Shandong, People's Republic of China
| | - Milan Certik
- Institute of Biotechnology, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinskeho 9, 812 37, Bratislava, Slovakia
| | - Victoriano Garre
- Departmento de Genética Y Microbiología (Unidad Asociada Al Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain.
| | - Yuanda Song
- Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255000, Shandong, People's Republic of China.
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11
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Mihara Y, Akiba J, Ogasawara S, Kondo R, Fukushima H, Itadani H, Obara H, Kakuma T, Kusano H, Naito Y, Okuda K, Nakashima O, Yano H. Malic enzyme 1 is a potential marker of combined hepatocellular cholangiocarcinoma, subtype with stem-cell features, intermediate-cell type. Hepatol Res 2019; 49:1066-1075. [PMID: 31077496 DOI: 10.1111/hepr.13365] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 04/17/2019] [Accepted: 04/21/2019] [Indexed: 12/12/2022]
Abstract
AIM Combined hepatocellular cholangiocarcinoma, subtype with stem-cell features, intermediate-cell subtype (INT) shows various histological appearances and could be misdiagnosed as intrahepatic cholangiocarcinoma (iCCA). In the present study, we aimed to identify specific histological diagnostic markers of INT. METHODS We extracted RNA from FFPE sections of six INT, five iCCA, and five hepatocellular carcinoma (HCC) cases and compared gene expression between INT, iCCA, and HCC by microarray analysis. We then undertook immunohistochemical (IHC) staining of potential key molecules identified by microarray analysis, the conventional hepatocytic marker, hepatocyte paraffin (HepPar)-1, and the cholangiocytic markers, keratin (K) 7 and K19, on 35 INT, 25 iCCA, and 60 HCC cases. RESULTS Microarray analysis suggested that malic enzyme 1 (ME1) was significantly upregulated in INT. Immunohistochemical analysis revealed that the positive rates of ME1 in INT, iCCA, and HCC were 77.1% (27/35), 28.0% (7/25), and 61.7% (37/60), respectively. Analysis of classification and regression trees based on IHC scores indicated that HepPar-1 could be a good candidate for discriminating HCC from the others with high sensitivity (93.3%) and high specificity (96.7%). A multiple logistic regression model and receiver operating characteristic curve analysis based on the IHC scores of ME1, K7, and K19 generated a composite score that can discriminate between INT and iCCA. Using this composite score, INT could be discriminated from iCCA with high sensitivity (88.6%) and high specificity (88.0%). CONCLUSIONS We propose that ME1 is a useful diagnostic marker of INT when used in combination with other hepatocytic and cholangiocytic markers.
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Affiliation(s)
- Yutaro Mihara
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Jun Akiba
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan.,Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan
| | - Sachiko Ogasawara
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Reiichiro Kondo
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Hiroto Fukushima
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd, Tsukuba, Japan
| | - Hiraku Itadani
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co., Ltd, Tsukuba, Japan
| | - Hitoshi Obara
- Department of Biostatistics Center, Kurume University, Kurume, Japan
| | - Tatsuyuki Kakuma
- Department of Biostatistics Center, Kurume University, Kurume, Japan
| | - Hironori Kusano
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Yoshiki Naito
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan.,Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan
| | - Koji Okuda
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, Kurume University School of Medicine, Kurume, Japan
| | - Osamu Nakashima
- Clinical Laboratory Medicine, Kurume University Hospital, Kurume, Japan
| | - Hirohisa Yano
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
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12
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Junghans L, Teleki A, Wijaya AW, Becker M, Schweikert M, Takors R. From nutritional wealth to autophagy: In vivo metabolic dynamics in the cytosol, mitochondrion and shuttles of IgG producing CHO cells. Metab Eng 2019; 54:145-159. [PMID: 30930288 DOI: 10.1016/j.ymben.2019.02.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 01/27/2019] [Accepted: 02/27/2019] [Indexed: 10/27/2022]
Abstract
To fulfil the optimization needs of current biopharmaceutical processes the knowledge how to improve cell specific productivities is of outmost importance. This requires a detailed understanding of cellular metabolism on a subcellular level inside compartments such as cytosol and mitochondrion. Using IgG1 producing Chinese hamster ovary (CHO) cells, a pioneering protocol for compartment-specific metabolome analysis was applied. Various production-like growth conditions ranging from ample glucose and amino acid supply via moderate to severe nitrogen limitation were investigated in batch cultures. The combined application of quantitative metabolite pool analysis, 13C tracer studies and non-stationary flux calculations revealed that Pyr/H+ symport (MPC1/2) bore the bulk of the mitochondrial transport under ample nutrient supply. Glutamine limitation induced the concerted adaptation of the bidirectional Mal/aKG (OGC) and the Mal/HPO42- antiporter (DIC), even installing completely reversed shuttle fluxes. As a result, NADPH and ATP formation were adjusted to cellular needs unraveling the key role of cytosolic malic enzyme for NADPH production. Highest cell specific IgG1 productivities were closely correlated to a strong mitochondrial malate export according to the anabolic demands. The requirement to install proper NADPH supply for optimizing the production of monoclonal antibodies is clearly outlined. Interestingly, it was observed that mitochondrial citric acid cycle activity was always maintained enabling constant cytosolic adenylate energy charges at physiological levels, even under autophagy conditions.
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Affiliation(s)
- Lisa Junghans
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Attila Teleki
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Andy Wiranata Wijaya
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Max Becker
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany
| | - Michael Schweikert
- Institute of Biomaterials and Biomolecular Systems, Department of Biobased Materials, University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany.
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13
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Gerencser AA. Metabolic activation-driven mitochondrial hyperpolarization predicts insulin secretion in human pancreatic beta-cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:817-828. [PMID: 29886047 DOI: 10.1016/j.bbabio.2018.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/18/2018] [Accepted: 06/05/2018] [Indexed: 12/31/2022]
Abstract
Mitochondrial metabolism plays a central role in insulin secretion in pancreatic beta-cells. Generation of protonmotive force and ATP synthesis from glucose-originated pyruvate are critical steps in the canonical pathway of glucose-stimulated insulin secretion. Mitochondrial metabolism is intertwined with pathways that are thought to amplify insulin secretion with mechanisms distinct from the canonical pathway, and the relative importance of these two pathways is controversial. Here I show that glucose-induced mitochondrial membrane potential (MMP) hyperpolarization is necessary for, and predicts, the rate of insulin secretion in primary cultured human beta-cells. When glucose concentration is elevated, increased metabolism results in a substantial MMP hyperpolarization, as well as in increased rates of ATP synthesis and turnover marked by faster cell respiration. Using modular kinetic analysis I explored what properties of cellular energy metabolism enable a large glucose-induced change in MMP in human beta-cells. I found that an ATP-dependent pathway activates glucose or substrate oxidation, acting as a positive feedback in energy metabolism. This activation mechanism is essential for concomitant fast respiration and high MMP, and for a high magnitude glucose-induced MMP hyperpolarization and therefore for insulin secretion.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Image Analyst Software, 43 Nova Lane, Novato, CA 94945, United States.
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14
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Abstract
Pancreatic islet β cells secrete insulin in response to nutrient secretagogues, like glucose, dependent on calcium influx and nutrient metabolism. One of the most intriguing qualities of β cells is their ability to use metabolism to amplify the amount of secreted insulin independent of further alterations in intracellular calcium. Many years studying this amplifying process have shaped our current understanding of β cell stimulus-secretion coupling; yet, the exact mechanisms of amplification have been elusive. Recent studies utilizing metabolomics, computational modeling, and animal models have progressed our understanding of the metabolic amplifying pathway of insulin secretion from the β cell. New approaches will be discussed which offer in-roads to a more complete model of β cell function. The development of β cell therapeutics may be aided by such a model, facilitating the targeting of aspects of the metabolic amplifying pathway which are unique to the β cell.
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Affiliation(s)
- Michael A Kalwat
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States.
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
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15
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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16
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Eanes WF. New views on the selection acting on genetic polymorphism in central metabolic genes. Ann N Y Acad Sci 2016; 1389:108-123. [PMID: 27859384 DOI: 10.1111/nyas.13285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/20/2016] [Accepted: 09/29/2016] [Indexed: 12/14/2022]
Abstract
Studies of the polymorphism of central metabolic genes as a source of fitness variation in natural populations date back to the discovery of allozymes in the 1960s. The unique features of these genes and their enzymes and our knowledge base greatly facilitates the systems-level study of this group. The expectation that pathway flux control is central to understanding the molecular evolution of genes is discussed, as well as studies that attempt to place gene-specific molecular evolution and polymorphism into a context of pathway and network architecture. There is an increasingly complex picture of the metabolic genes assuming additional roles beyond their textbook anabolic and catabolic reactions. In particular, this review emphasizes the potential role of these genes as part of the energy-sensing machinery. It is underscored that the concentrations of key cellular metabolites are the reflections of cellular energy status and nutritional input. These metabolites are the top-down signaling messengers that set signaling through signaling pathways that are involved in energy economy. I propose that the polymorphisms in central metabolic genes shift metabolite concentrations and in that fashion act as genetic modifiers of the energy-state coupling to the transcriptional networks that affect physiological trade-offs with significant fitness consequences.
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Affiliation(s)
- Walter F Eanes
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York
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17
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NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) and cytochrome P450 oxidoreductase (CYP450OR) differentially regulate menadione-mediated alterations in redox status, survival and metabolism in pancreatic β-cells. Toxicol Lett 2016; 262:1-11. [PMID: 27558805 DOI: 10.1016/j.toxlet.2016.08.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/27/2016] [Accepted: 08/20/2016] [Indexed: 01/08/2023]
Abstract
NQO1 (NAD(P)H-quinone oxidoreductase 1) reduces quinones and xenobiotics to less-reactive compounds via 2-electron reduction, one feature responsible for the role of NQO1 in antioxidant defense in several tissues. In contrast, NADPH cytochrome P450 oxidoreductase (CYP450OR), catalyzes the 1-electron reduction of quinones and xenobiotics, resulting in enhanced superoxide formation. However, to date, the roles of NQO1 and CYP450OR in pancreatic β-cell metabolism under basal conditions and oxidant challenge have not been characterized. Using NQO1 inhibition, over-expression and knock out, we have demonstrated that, in addition to protection of β-cells from toxic concentrations of the redox cycling quinone menadione, NQO1 also regulates the basal level of reduced-to-oxidized nucleotides, suggesting other role(s) beside that of an antioxidant enzyme. In contrast, over-expression of NADPH cytochrome P450 oxidoreductase (CYP450OR) resulted in enhanced redox cycling activity and decreased cellular viability, consistent with the enhanced generation of superoxide and H2O2. Basal expression of NQO1 and CYP450OR was comparable in isolated islets and liver. However, NQO1, but not CYP450OR, was strongly induced in β-cells exposed to menadione. NQO1 and CYP450OR exhibited a reciprocal preference for reducing equivalents in β-cells: while CYP450OR preferentially utilized NADPH, NQO1 primarily utilized NADH. Together, these results demonstrate that NQO1 and CYP450OR reciprocally regulate oxidant metabolism in pancreatic β-cells.
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18
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Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells. PLoS One 2016; 11:e0159199. [PMID: 27404273 PMCID: PMC4942067 DOI: 10.1371/journal.pone.0159199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/28/2016] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions.
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Affiliation(s)
- Akos A. Gerencser
- Buck Institute for Research on Aging, Novato, California, United States of America
- Image Analyst Software, Novato, California, United States of America
| | - Shona A. Mookerjee
- Buck Institute for Research on Aging, Novato, California, United States of America
- Touro University California College of Pharmacy, Vallejo, California, United States of America
| | - Martin Jastroch
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Martin D. Brand
- Buck Institute for Research on Aging, Novato, California, United States of America
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19
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Heart EA, Karandrea S, Liang X, Balke ME, Beringer PA, Bobczynski EM, Zayas-Bazán Burgos D, Richardson T, Gray JP. Mechanisms of Doxorubicin Toxicity in Pancreatic β-Cells. Toxicol Sci 2016; 152:395-405. [PMID: 27255381 DOI: 10.1093/toxsci/kfw096] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Exposure to chemotherapeutic agents has been linked to an increased risk of type 2 diabetes (T2D), a disease characterized by both the peripheral insulin resistance and impaired glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. Using the rat β-cell line INS-1 832/13 and isolated mouse pancreatic islets, we investigated the effect of the chemotherapeutic drug doxorubicin (Adriamycin) on pancreatic β-cell survival and function. Exposure of INS-1 832/13 cells to doxorubicin caused impairment of GSIS, cellular viability, an increase in cellular toxicity, as soon as 6 h post-exposure. Doxorubicin impaired plasma membrane electron transport (PMET), a pathway dependent on reduced equivalents NADH and NADPH, but failed to redox cycle in INS-1 832/13 cells and with their lysates. Although NADPH/NADP(+ )content was unaffected, NADH/NAD(+ )content decreased at 4 h post-exposure to doxorubicin, and was followed by a reduction in ATP content. Previous studies have demonstrated that doxorubicin functions as a topoisomerase II inhibitor via induction of DNA cross-linking, resulting in apoptosis. Doxorubicin induced the expression of mRNA for mdm2, cyclin G1, and fas whereas downregulating p53, and increased the melting temperature of genomic DNA, consistent with DNA damage and induction of apoptosis. Doxorubicin also induced caspase-3 and -7 activity in INS-1 832/13 cells and mouse islets; co-treatment with the pan-caspase inhibitor Z-VAD-FMK temporarily attenuated the doxorubicin-mediated loss of viability in INS-1 832/13 cells. Together, these data suggest that DNA damage, not H2O2 produced via redox cycling, is a major mechanism of doxorubicin toxicity in pancreatic β-cells.
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Affiliation(s)
- Emma A Heart
- *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Shpetim Karandrea
- *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Xiaomei Liang
- *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Maren E Balke
- Department of Science, United States Coast Guard Academy, New London, Connecticut 06320
| | - Patrick A Beringer
- Department of Science, United States Coast Guard Academy, New London, Connecticut 06320
| | - Elyse M Bobczynski
- Department of Science, United States Coast Guard Academy, New London, Connecticut 06320
| | | | | | - Joshua P Gray
- *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612 Department of Science, United States Coast Guard Academy, New London, Connecticut 06320
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20
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Gray JP, Burgos DZ, Yuan T, Seeram N, Rebar R, Follmer R, Heart EA. Thymoquinone, a bioactive component of Nigella sativa, normalizes insulin secretion from pancreatic β-cells under glucose overload via regulation of malonyl-CoA. Am J Physiol Endocrinol Metab 2016; 310:E394-404. [PMID: 26786775 PMCID: PMC4796268 DOI: 10.1152/ajpendo.00250.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 01/11/2016] [Indexed: 12/18/2022]
Abstract
Thymoquinone (2-isopropyl-5-methylbenzo-1,4-quinone) is a major bioactive component of Nigella sativa, a plant used in traditional medicine to treat a variety of symptoms, including elevated blood glucose levels in type 2 diabetic patients. Normalization of elevated blood glucose depends on both glucose disposal by peripheral tissues and glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. We employed clonal β-cells and rodent islets to investigate the effects of thymoquinone (TQ) and Nigella sativa extracts (NSEs) on GSIS and cataplerotic metabolic pathways implicated in the regulation of GSIS. TQ and NSE regulated NAD(P)H/NAD(P)(+) ratios via a quinone-dependent redox cycling mechanism. TQ content was positively correlated with the degree of redox cycling activity of NSE extracts, suggesting that TQ is a major component engaged in mediating NSE-dependent redox cycling. Both acute and chronic exposure to TQ and NSE enhanced GSIS and were associated with the ability of TQ and NSE to increase the ATP/ADP ratio. Furthermore, TQ ameliorated the impairment of GSIS following chronic exposure of β-cells to glucose overload. This protective action was associated with the TQ-dependent normalization of chronic accumulation of malonyl-CoA, elevation of acetyl-CoA carboxylase (ACC), fatty acid synthase, and fatty acid-binding proteins following chronic glucose overload. Together, these data suggest that TQ modulates the β-cell redox circuitry and enhances the sensitivity of β-cell metabolic pathways to glucose and GSIS under normal conditions as well as under hyperglycemia. This action is associated with the ability of TQ to regulate carbohydrate-to-lipid flux via downregulation of ACC and malonyl-CoA.
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Affiliation(s)
- Joshua P Gray
- Department of Science, United States Coast Guard Academy, New London, Connecticut
| | | | - Tao Yuan
- Department of Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island
| | - Navindra Seeram
- Department of Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island
| | - Rebecca Rebar
- Department of Science, United States Coast Guard Academy, New London, Connecticut
| | - Rebecca Follmer
- Department of Science, United States Coast Guard Academy, New London, Connecticut
| | - Emma A Heart
- Department of Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island; Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida; and Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts
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21
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High dietary cholesterol intake during lactation promotes development of fatty liver in offspring of mice. Mol Nutr Food Res 2016; 60:1110-7. [DOI: 10.1002/mnfr.201500736] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/28/2015] [Accepted: 01/17/2016] [Indexed: 02/05/2023]
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22
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Hasan NM, Longacre MJ, Stoker SW, Kendrick MA, MacDonald MJ. Mitochondrial malic enzyme 3 is important for insulin secretion in pancreatic β-cells. Mol Endocrinol 2015; 29:396-410. [PMID: 25594249 DOI: 10.1210/me.2014-1249] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pancreatic β-cells with severely knocked down cytosolic malic enzyme (ME1) and mitochondrial NAD(P) malic enzyme (ME2) show normal insulin secretion. The mitochondrial NADP malic enzyme (ME3) is very low in pancreatic β-cells, and ME3 was previously thought unimportant for insulin secretion. Using short hairpin RNAs that targeted one or more malic enzyme mRNAs in the same cell, we generated more than 25 stable INS-1 832/13-derived insulin cell lines expressing extremely low levels of ME1, ME2, and ME3 alone or low levels of two of these enzymes in the same cell line. We also used double targeting of the same Me gene to achieve even more severe reduction in Me1 and Me2 mRNAs and enzyme activities than we reported previously. Knockdown of ME3, but not ME1 or ME2 alone or together, inhibited insulin release stimulated by glucose, pyruvate or 2-aminobicyclo [2,2,1]heptane-2-carboxylic acid-plus-glutamine. The data suggest that ME3, far more than ME1 or ME2, is necessary for insulin release. Because ME3 enzyme activity is low in β-cells, its role in insulin secretion may involve a function other than its ME catalytic activity.
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Affiliation(s)
- Noaman M Hasan
- Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
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23
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Streptococcus pyogenes malate degradation pathway links pH regulation and virulence. Infect Immun 2015; 83:1162-71. [PMID: 25583521 DOI: 10.1128/iai.02814-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ability of Streptococcus pyogenes to infect different niches within its human host most likely relies on its ability to utilize alternative carbon sources. In examining this question, we discovered that all sequenced S. pyogenes strains possess the genes for the malic enzyme (ME) pathway, which allows malate to be used as a supplemental carbon source for growth. ME is comprised of four genes in two adjacent operons, with the regulatory two-component MaeKR required for expression of genes encoding a malate permease (maeP) and malic enzyme (maeE). Analysis of transcription indicated that expression of maeP and maeE is induced by both malate and low pH, and induction in response to both cues is dependent on the MaeK sensor kinase. Furthermore, both maePE and maeKR are repressed by glucose, which occurs via a CcpA-independent mechanism. Additionally, malate utilization requires the PTS transporter EI enzyme (PtsI), as a PtsI(-) mutant fails to express the ME genes and is unable to utilize malate. Virulence of selected ME mutants was assessed in a murine model of soft tissue infection. MaeP(-), MaeK(-), and MaeR(-) mutants were attenuated for virulence, whereas a MaeE(-) mutant showed enhanced virulence compared to that of the wild type. Taken together, these data show that ME contributes to S. pyogenes' carbon source repertory, that malate utilization is a highly regulated process, and that a single regulator controls ME expression in response to diverse signals. Furthermore, malate uptake and utilization contribute to the adaptive pH response, and ME can influence the outcome of infection.
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24
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Luo X, Li R, Yan LJ. Roles of Pyruvate, NADH, and Mitochondrial Complex I in Redox Balance and Imbalance in β Cell Function and Dysfunction. J Diabetes Res 2015; 2015:512618. [PMID: 26568959 PMCID: PMC4629043 DOI: 10.1155/2015/512618] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/26/2014] [Accepted: 11/27/2014] [Indexed: 12/25/2022] Open
Abstract
Pancreatic β cells not only use glucose as an energy source, but also sense blood glucose levels for insulin secretion. While pyruvate and NADH metabolic pathways are known to be involved in regulating insulin secretion in response to glucose stimulation, the roles of many other components along the metabolic pathways remain poorly understood. Such is the case for mitochondrial complex I (NADH/ubiquinone oxidoreductase). It is known that normal complex I function is absolutely required for episodic insulin secretion after a meal, but the role of complex I in β cells in the diabetic pancreas remains to be investigated. In this paper, we review the roles of pyruvate, NADH, and complex I in insulin secretion and hypothesize that complex I plays a crucial role in the pathogenesis of β cell dysfunction in the diabetic pancreas. This hypothesis is based on the establishment that chronic hyperglycemia overloads complex I with NADH leading to enhanced complex I production of reactive oxygen species. As nearly all metabolic pathways are impaired in diabetes, understanding how complex I in the β cells copes with elevated levels of NADH in the diabetic pancreas may provide potential therapeutic strategies for diabetes.
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Affiliation(s)
- Xiaoting Luo
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
- Department of Biochemistry and Molecular Biology, Gannan Medical University, Ganzhou, Jiangxi 341000, China
| | - Rongrong Li
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Liang-Jun Yan
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
- *Liang-Jun Yan:
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25
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Kim GH, Lee YE, Lee GH, Cho YH, Lee YN, Jang Y, Paik D, Park JJ. Overexpression of malic enzyme in the larval stage extends Drosophila lifespan. Biochem Biophys Res Commun 2014; 456:676-82. [PMID: 25511696 DOI: 10.1016/j.bbrc.2014.12.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 12/05/2014] [Indexed: 02/01/2023]
Abstract
Metabolic modifications during the developmental period can extend longevity. We found that malic enzyme (Men) overexpression during the larval period lengthened the lifespan of Drosophila. Men overexpression by S106-GeneSwitch-Gal4 driver increased pyruvate content and NADPH/NADP(+) ratio but reduced triglyceride, glycogen, and ATP levels in the larvae. ROS levels increased unexpectedly in Men-overexpressing larvae. Interestingly, adults exposed to larval Men-overexpression maintained ROS tolerance with enhanced expression levels of glutathione-S-transferase D2 and thioredoxin-2. Our results suggest that metabolic changes mediated by Men during development might be related to the control of ROS tolerance and the longevity of Drosophila.
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Affiliation(s)
- Gye-Hyeong Kim
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Young-Eun Lee
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Gun-Ho Lee
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Youn-Ho Cho
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Young-Nam Lee
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Yeogil Jang
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Donggi Paik
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea
| | - Joong-Jean Park
- Department of Physiology, College of Medicine, Korea University, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Republic of Korea.
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26
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Knockdown of malic enzyme 2 suppresses lung tumor growth, induces differentiation and impacts PI3K/AKT signaling. Sci Rep 2014; 4:5414. [PMID: 24957098 PMCID: PMC4067620 DOI: 10.1038/srep05414] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 06/02/2014] [Indexed: 12/30/2022] Open
Abstract
Mitochondrial malic enzyme 2 (ME2) catalyzes the oxidative decarboxylation of malate to yield CO2 and pyruvate, with concomitant reduction of dinucleotide cofactor NAD+ or NADP+. We find that ME2 is highly expressed in many solid tumors. In the A549 non-small cell lung cancer (NSCLC) cell line, ME2 depletion inhibits cell proliferation and induces cell death and differentiation, accompanied by increased reactive oxygen species (ROS) and NADP+/NADPH ratio, a drop in ATP, and increased sensitivity to cisplatin. ME2 knockdown impacts phosphoinositide-dependent protein kinase 1 (PDK1) and phosphatase and tensin homolog (PTEN) expression, leading to AKT inhibition. Depletion of ME2 leads to malate accumulation and pyruvate decrease, and exogenous cell permeable dimethyl-malate (DMM) mimics the ME2 knockdown phenotype. Both ME2 knockdown and DMM treatment reduce A549 cell growth in vivo. Collectively, our data suggest that ME2 is a potential target for cancer therapy.
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Stark R, Kibbey RG. The mitochondrial isoform of phosphoenolpyruvate carboxykinase (PEPCK-M) and glucose homeostasis: has it been overlooked? BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1840:1313-30. [PMID: 24177027 PMCID: PMC3943549 DOI: 10.1016/j.bbagen.2013.10.033] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 10/13/2013] [Accepted: 10/18/2013] [Indexed: 01/03/2023]
Abstract
BACKGROUND Plasma glucose levels are tightly regulated within a narrow physiologic range. Insulin-mediated glucose uptake by tissues must be balanced by the appearance of glucose from nutritional sources, glycogen stores, or gluconeogenesis. In this regard, a common pathway regulating both glucose clearance and appearance has not been described. The metabolism of glucose to produce ATP is generally considered to be the primary stimulus for insulin release from beta-cells. Similarly, gluconeogenesis from phosphoenolpyruvate (PEP) is believed to be the primarily pathway via the cytosolic isoform of phosphoenolpyruvate carboxykinase (PEPCK-C). These models cannot adequately explain the regulation of insulin secretion or gluconeogenesis. SCOPE OF REVIEW A metabolic sensing pathway involving mitochondrial GTP (mtGTP) and PEP synthesis by the mitochondrial isoform of PEPCK (PEPCK-M) is associated with glucose-stimulated insulin secretion from pancreatic beta-cells. Here we examine whether there is evidence for a similar mtGTP-dependent pathway involved in gluconeogenesis. In both islets and the liver, mtGTP is produced at the substrate level by the enzyme succinyl CoA synthetase (SCS-GTP) with a rate proportional to the TCA cycle. In the beta-cell PEPCK-M then hydrolyzes mtGTP in the production of PEP that, unlike mtGTP, can escape the mitochondria to generate a signal for insulin release. Similarly, PEPCK-M and mtGTP might also provide a significant source of PEP in gluconeogenic tissues for the production of glucose. This review will focus on the possibility that PEPCK-M, as a sensor for TCA cycle flux, is a key mechanism to regulate both insulin secretion and gluconeogenesis suggesting conservation of this biochemical mechanism in regulating multiple aspects of glucose homeostasis. Moreover, we propose that this mechanism may be important for regulating insulin secretion and gluconeogenesis compared to canonical nutrient sensing pathways. MAJOR CONCLUSIONS PEPCK-M, initially believed to be absent in islets, carries a substantial metabolic flux in beta-cells. This flux is intimately involved with the coupling of glucose-stimulated insulin secretion. PEPCK-M activity may have been similarly underestimated in glucose producing tissues and could potentially be an unappreciated but important source of gluconeogenesis. GENERAL SIGNIFICANCE The generation of PEP via PEPCK-M may occur via a metabolic sensing pathway important for regulating both insulin secretion and gluconeogenesis. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Romana Stark
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
| | - Richard G Kibbey
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
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JEŽEK P, OLEJÁR T, SMOLKOVÁ K, JEŽEK J, DLASKOVÁ A, PLECITÁ-HLAVATÁ L, ZELENKA J, ŠPAČEK T, ENGSTOVÁ H, PAJUELO REGUERA D, JABŮREK M. Antioxidant and Regulatory Role of Mitochondrial Uncoupling Protein UCP2 in Pancreatic β-cells. Physiol Res 2014; 63:S73-91. [DOI: 10.33549/physiolres.932633] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on brown adipose tissue and its hallmark protein, mitochondrial uncoupling protein UCP1, has been conducted for half a century and has been traditionally studied in the Institute of Physiology (AS CR, Prague), likewise UCP2 residing in multiple tissues for the last two decades. Our group has significantly contributed to the elucidation of UCP uncoupling mechanism, fully dependent on free fatty acids (FFAs) within the inner mitochondrial membrane. Now we review UCP2 physiological roles emphasizing its roles in pancreatic β-cells, such as antioxidant role, possible tuning of redox homeostasis (consequently UCP2 participation in redox regulations), and fine regulation of glucose-stimulated insulin secretion (GSIS). For example, NADPH has been firmly established as being a modulator of GSIS and since UCP2 may influence redox homeostasis, it likely affects NADPH levels. We also point out the role of phospholipase iPLA2 isoform in providing FFAs for the UCP2 antioxidant function. Such initiation of mild uncoupling hypothetically precedes lipotoxicity in pancreatic β-cells until it reaches the pathological threshold, after which the antioxidant role of UCP2 can be no more cell-protective, for example due to oxidative stress-accumulated mutations in mtDNA. These mechanisms, together with impaired autocrine insulin function belong to important causes of Type 2 diabetes etiology.
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Affiliation(s)
- P. JEŽEK
- Department of Membrane Transport Biophysics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Liu J, Guo L, Yin F, Zhang Y, Liu Z, Wang Y. Geniposide regulates glucose-stimulated insulin secretion possibly through controlling glucose metabolism in INS-1 cells. PLoS One 2013; 8:e78315. [PMID: 24167617 PMCID: PMC3805567 DOI: 10.1371/journal.pone.0078315] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 09/11/2013] [Indexed: 12/26/2022] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) is essential to the control of metabolic fuel homeostasis. The impairment of GSIS is a key element of β-cell failure and one of causes of type 2 diabetes mellitus (T2DM). Although the KATP channel-dependent mechanism of GSIS has been broadly accepted for several decades, it does not fully describe the effects of glucose on insulin secretion. Emerging evidence has suggested that other mechanisms are involved. The present study demonstrated that geniposide enhanced GSIS in response to the stimulation of low or moderately high concentrations of glucose, and promoted glucose uptake and intracellular ATP levels in INS-1 cells. However, in the presence of a high concentration of glucose, geniposide exerted a contrary role on both GSIS and glucose uptake and metabolism. Furthermore, geniposide improved the impairment of GSIS in INS-1 cells challenged with a high concentration of glucose. Further experiments showed that geniposide modulated pyruvate carboxylase expression and the production of intermediates of glucose metabolism. The data collectively suggest that geniposide has potential to prevent or improve the impairment of insulin secretion in β-cells challenged with high concentrations of glucose, likely through pyruvate carboxylase mediated glucose metabolism in β-cells.
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Affiliation(s)
- Jianhui Liu
- Chongqing Key Laboratory of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing, China
- Chongqing Key Laboratory of Natural Medicine Research, Chongqing Technology and Business University, Chongqing, China
- Aquatic and Crop Resource Development, National Research Council of Canada, Charlottetown, Prince Edward Island, Canada
- * E-mail:
| | - Lixia Guo
- Chongqing Key Laboratory of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing, China
- Chongqing Key Laboratory of Natural Medicine Research, Chongqing Technology and Business University, Chongqing, China
| | - Fei Yin
- Chongqing Key Laboratory of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing, China
- Chongqing Key Laboratory of Natural Medicine Research, Chongqing Technology and Business University, Chongqing, China
- Aquatic and Crop Resource Development, National Research Council of Canada, Charlottetown, Prince Edward Island, Canada
| | - Yonglan Zhang
- Chongqing Key Laboratory of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing, China
- Chongqing Key Laboratory of Natural Medicine Research, Chongqing Technology and Business University, Chongqing, China
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, China
| | - Zixuan Liu
- Chongqing Key Laboratory of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing, China
- Chongqing Key Laboratory of Natural Medicine Research, Chongqing Technology and Business University, Chongqing, China
| | - Yanwen Wang
- Aquatic and Crop Resource Development, National Research Council of Canada, Charlottetown, Prince Edward Island, Canada
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Abstract
The pancreatic islet β cell senses circulating levels of calorigenic nutrients to secrete insulin according to the needs of the organism. Altered insulin secretion is linked to various disorders such as diabetes, hypoglycemic states, and cardiometabolic diseases. Fuel stimuli, including glucose, free fatty acids, and amino acids, promote insulin granule exocytosis primarily via their metabolism in β cells and the production of key signaling metabolites. This paper reviews our current knowledge of the pathways involved in both positive and negative metabolic signaling for insulin secretion and assesses the role of established and candidate metabolic coupling factors, keeping recent developments in focus.
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Affiliation(s)
- Marc Prentki
- Molecular Nutrition Unit, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, QC, Canada.
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Redox homeostasis in pancreatic β cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:932838. [PMID: 23304259 PMCID: PMC3532876 DOI: 10.1155/2012/932838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 12/20/2022]
Abstract
We reviewed mechanisms that determine reactive oxygen species (redox) homeostasis, redox information signaling and metabolic/regulatory function of autocrine insulin signaling in pancreatic β cells, and consequences of oxidative stress and dysregulation of redox/information signaling for their dysfunction. We emphasize the role of mitochondrion in β cell molecular physiology and pathology, including the antioxidant role of mitochondrial uncoupling protein UCP2. Since in pancreatic β cells pyruvate cannot be easily diverted towards lactate dehydrogenase for lactate formation, the respiration and oxidative phosphorylation intensity are governed by the availability of glucose, leading to a certain ATP/ADP ratio, whereas in other cell types, cell demand dictates respiration/metabolism rates. Moreover, we examine the possibility that type 2 diabetes mellitus might be considered as an inevitable result of progressive self-accelerating oxidative stress and concomitantly dysregulated information signaling in peripheral tissues as well as in pancreatic β cells. It is because the redox signaling is inherent to the insulin receptor signaling mechanism and its impairment leads to the oxidative and nitrosative stress. Also emerging concepts, admiting participation of redox signaling even in glucose sensing and insulin release in pancreatic β cells, fit in this view. For example, NADPH has been firmly established to be a modulator of glucose-stimulated insulin release.
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Al-Dwairi A, Pabona JMP, Simmen RCM, Simmen FA. Cytosolic malic enzyme 1 (ME1) mediates high fat diet-induced adiposity, endocrine profile, and gastrointestinal tract proliferation-associated biomarkers in male mice. PLoS One 2012; 7:e46716. [PMID: 23056418 PMCID: PMC3464285 DOI: 10.1371/journal.pone.0046716] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 09/01/2012] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Obesity and associated hormonal disturbances are risk factors for colon cancer. Cytosolic Malic Enzyme (ME1) generates NADPH used for lipogenesis in gastrointestinal (GI), liver and adipose tissues. We have reported that inclusion of soy protein isolate (SPI) in the diet lowered body fat content and colon tumor incidence of rats fed AIN-93G diet, while others have demonstrated SPI inhibition of rat hepatic ME1 expression. The present study examined the individual and combined effects of dietary SPI and absence of ME1 on: 1) serum concentrations of hormones implicated in colon cancer development, 2) expression of lipogenic and proliferation-associated genes in the mouse colon and small intestine, and 3) liver and adipose expression of lipogenic and adipocytokine genes that may contribute to colon cancer predisposition. METHODS Weanling wild type (WT) and ME1 null (MOD-1) male mice were fed high-fat (HF), iso-caloric diets containing either casein (CAS) or SPI as sole protein source for 5 wks. Somatic growth, serum hormone and glucose levels, liver and adipose tissue weights, GI tissue parameters, and gene expression were evaluated. RESULTS The MOD-1 genotype and SPI-HF diet resulted in decreases in: body and retroperitoneal fat weights, serum insulin, serum leptin, leptin/adiponectin ratio, adipocyte size, colon mTOR and cyclin D1 mRNA abundance, and jejunum FASN mRNA abundance, when compared to WT mice fed CAS-HF. Regardless of diet, MOD-1 mice had reductions in liver weight, liver steatosis, and colon crypt depth, and increases in adipose tissue expression of IRS1 and IRS2, compared to WT mice. SPI-HF diet reduced ME1 gene expression only in retroperitoneal fat. CONCLUSIONS Data suggest that the pharmacological targeting of ME1 or the inclusion of soy protein in the diet may provide avenues to reduce obesity and its associated pro-tumorigenic endocrine environment and improve insulin sensitivity, potentially disrupting the obesity-colon cancer connection.
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Affiliation(s)
- Ahmed Al-Dwairi
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - John Mark P. Pabona
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- Arkansas Children’s Nutrition Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Rosalia C. M. Simmen
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- Arkansas Children’s Nutrition Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Frank A. Simmen
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
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Sugden MC, Holness MJ. The pyruvate carboxylase-pyruvate dehydrogenase axis in islet pyruvate metabolism: Going round in circles? Islets 2011; 3:302-19. [PMID: 21934355 PMCID: PMC3329512 DOI: 10.4161/isl.3.6.17806] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Pyruvate is the major product of glycolysis in pancreatic β-cells, and its ultimate metabolic fate depends on the relative activities of two enzymes. The first, pyruvate carboxylase (PC) replenishes oxaloacetate withdrawn from the tricarboxylic acid (TCA) cycle via the carboxylation of pyruvate to form oxaloacetate. Flux via PC is also involved in the formation of NADPH, one of several important coupling factors for insulin secretion. In most tissues, PC activity is enhanced by increased acetyl-CoA. The alternative fate of pyruvate is its oxidative decarboxylation to form acetyl-CoA via the pyruvate dehydrogenase complex (PDC). The ultimate fate of acetyl-CoA carbon is oxidation to CO2 via the TCA cycle, and so the PDC reaction results of the irreversible loss of glucose-derived carbon. Thus, PDC activity is stringently regulated. The mechanisms controlling PDC activity include end-product inhibition by increased acetyl-CoA, NADH and ATP, and its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDHKs 1-4). Here we review new developments in the regulation of the activities and expression of PC, PDC and the PDHKs in the pancreatic islet in relation to islet pyruvate disposition and glucose-stimulated insulin secretion (GSIS).
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Affiliation(s)
- Mary C Sugden
- Centre for Diabetes, Blizard Institute, Bart's and the London School of Medicine and Dentistry, London, UK.
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35
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Gray JP, Eisen T, Cline GW, Smith PJS, Heart E. Plasma membrane electron transport in pancreatic β-cells is mediated in part by NQO1. Am J Physiol Endocrinol Metab 2011; 301:E113-21. [PMID: 21505151 PMCID: PMC3129843 DOI: 10.1152/ajpendo.00673.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Plasma membrane electron transport (PMET), a cytosolic/plasma membrane analog of mitochondrial electron transport, is a ubiquitous system of cytosolic and plasma membrane oxidoreductases that oxidizes cytosolic NADH and NADPH and passes electrons to extracellular targets. While PMET has been shown to play an important role in a variety of cell types, no studies exist to evaluate its function in insulin-secreting cells. Here we demonstrate the presence of robust PMET activity in primary islets and clonal β-cells, as assessed by the reduction of the plasma membrane-impermeable dyes WST-1 and ferricyanide. Because the degree of metabolic function of β-cells (reflected by the level of insulin output) increases in a glucose-dependent manner between 4 and 10 mM glucose, PMET was evaluated under these conditions. PMET activity was present at 4 mM glucose and was further stimulated at 10 mM glucose. PMET activity at 10 mM glucose was inhibited by the application of the flavoprotein inhibitor diphenylene iodonium and various antioxidants. Overexpression of cytosolic NAD(P)H-quinone oxidoreductase (NQO1) increased PMET activity in the presence of 10 mM glucose while inhibition of NQO1 by its inhibitor dicoumarol abolished this activity. Mitochondrial inhibitors rotenone, antimycin A, and potassium cyanide elevated PMET activity. Regardless of glucose levels, PMET activity was greatly enhanced by the application of aminooxyacetate, an inhibitor of the malate-aspartate shuttle. We propose a model for the role of PMET as a regulator of glycolytic flux and an important component of the metabolic machinery in β-cells.
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Affiliation(s)
- Joshua P Gray
- United States Coast Guard Academy, New London, Connecticut, USA
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36
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Cruz-Topete D, List EO, Okada S, Kelder B, Kopchick JJ. Proteomic changes in the heart of diet-induced pre-diabetic mice. J Proteomics 2011; 74:716-27. [PMID: 21354350 PMCID: PMC3081671 DOI: 10.1016/j.jprot.2011.02.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/10/2011] [Accepted: 02/15/2011] [Indexed: 01/18/2023]
Abstract
The development of type 2 diabetes (T2D) is strongly associated with obesity. In humans, T2D increases the risk for end organ complications. Among these, heart disease has been ranked as the leading cause of death. We used a proteomic methodology to test the hypothesis that a pre-diabetic state generated by high-fat diet leads to changes in proteins related to heart function and structure. Over 300 protein spots were resolved by two-dimensional gel electrophoresis (2-DE). Fifteen protein spots were found to be altered (7 decreased and 8 increased) in pre-diabetic hearts. The protein spots were then identified by mass spectrometry and immunoblots. Among the decreased proteins, 3 are involved in heart structure (one isoform of desmin, troponin T2 and α-cardiac actin), 3 are involved in energy metabolism (mitochondrial ATP synthase β subunit, adenylate kinase and creatine kinase) and one is a component of the citric acid cycle (isocitrate dehydrogenase 3). In contrast, proteins involved in fatty acid oxidation (two isoforms of peroxisomal enoyl-CoA hydratase) and the citric acid cycle (three isoforms of malate dehydrogenase) were increased in pre-diabetic hearts. The results suggest that changes in the levels of several heart proteins may have implications in the development of the cardiac phenotype associated to T2D.
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Affiliation(s)
| | - Edward O. List
- Edison Biotechnology Institute, Ohio University, Athens, OH
| | - Shigeru Okada
- Edison Biotechnology Institute, Ohio University, Athens, OH
- Department of Pediatrics, College of Osteopathic Medicine, Ohio University, Athens, OH
| | - Bruce Kelder
- Edison Biotechnology Institute, Ohio University, Athens, OH
- Department of Pediatrics, College of Osteopathic Medicine, Ohio University, Athens, OH
| | - John J. Kopchick
- Edison Biotechnology Institute, Ohio University, Athens, OH
- Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens, OH
- Molecular and Cellular Biology Program, Ohio University, Athens, OH
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37
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Ufer C, Wang CC, Borchert A, Heydeck D, Kuhn H. Redox control in mammalian embryo development. Antioxid Redox Signal 2010; 13:833-75. [PMID: 20367257 DOI: 10.1089/ars.2009.3044] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The development of an embryo constitutes a complex choreography of regulatory events that underlies precise temporal and spatial control. Throughout this process the embryo encounters ever changing environments, which challenge its metabolism. Oxygen is required for embryogenesis but it also poses a potential hazard via formation of reactive oxygen and reactive nitrogen species (ROS/RNS). These metabolites are capable of modifying macromolecules (lipids, proteins, nucleic acids) and altering their biological functions. On one hand, such modifications may have deleterious consequences and must be counteracted by antioxidant defense systems. On the other hand, ROS/RNS function as essential signal transducers regulating the cellular phenotype. In this context the combined maternal/embryonic redox homeostasis is of major importance and dysregulations in the equilibrium of pro- and antioxidative processes retard embryo development, leading to organ malformation and embryo lethality. Silencing the in vivo expression of pro- and antioxidative enzymes provided deeper insights into the role of the embryonic redox equilibrium. Moreover, novel mechanisms linking the cellular redox homeostasis to gene expression regulation have recently been discovered (oxygen sensing DNA demethylases and protein phosphatases, redox-sensitive microRNAs and transcription factors, moonlighting enzymes of the cellular redox homeostasis) and their contribution to embryo development is critically reviewed.
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Affiliation(s)
- Christoph Ufer
- Institute of Biochemistry, University Medicine Berlin-Charité, Berlin, FR Germany
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38
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Gray JP, Heart E. Usurping the mitochondrial supremacy: extramitochondrial sources of reactive oxygen intermediates and their role in beta cell metabolism and insulin secretion. Toxicol Mech Methods 2010; 20:167-74. [PMID: 20397883 DOI: 10.3109/15376511003695181] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin secretion from pancreatic beta cells is a process dependent on metabolism. While oxidative stress is a well-known inducer of beta cell toxicity and impairs insulin secretion, recent studies suggest that low levels of metabolically-derived reactive oxygen intermediates (ROI) also play a positive role in insulin secretion. Glucose metabolism is directly correlated with ROI production, particularly in beta cells in which glucose uptake is proportional to the extracellular concentration of glucose. Low levels of exogenously added ROI or quinones, which stimulate ROI production, positively affect insulin secretion, while antioxidants block insulin secretion, suggesting that ROI activate unidentified redox-sensitive signal transduction components within these cells. The mitochondria are one source of ROI: increased metabolic flux increases mitochondrial membrane potential resulting in electron leakage and adventitious ROI production. A second source of ROI are cytosolic and plasma membrane oxidoreductases which oxidize NAD(P)H and directly produce ROI through the reduction of molecular oxygen. The mechanism of ROI-mediated potentiation of insulin secretion remains an important topic for future study.
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Affiliation(s)
- Joshua P Gray
- Department of Science, Chemistry Section, United States Coast Guard Academy, New London, CT 06320, USA.
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Jitrapakdee S, Wutthisathapornchai A, Wallace JC, MacDonald MJ. Regulation of insulin secretion: role of mitochondrial signalling. Diabetologia 2010; 53:1019-32. [PMID: 20225132 PMCID: PMC2885902 DOI: 10.1007/s00125-010-1685-0] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 01/06/2010] [Indexed: 12/23/2022]
Abstract
Pancreatic beta cells are specialised endocrine cells that continuously sense the levels of blood sugar and other fuels and, in response, secrete insulin to maintain normal fuel homeostasis. During postprandial periods an elevated level of plasma glucose rapidly stimulates insulin secretion to decrease hepatic glucose output and promote glucose uptake into other tissues, principally muscle and adipose tissues. Beta cell mitochondria play a key role in this process, not only by providing energy in the form of ATP to support insulin secretion, but also by synthesising metabolites (anaplerosis) that can act, both intra- and extramitochondrially, as factors that couple glucose sensing to insulin granule exocytosis. ATP on its own, and possibly modulated by these coupling factors, triggers closure of the ATP-sensitive potassium channel, resulting in membrane depolarisation that increases intracellular calcium to cause insulin secretion. The metabolic imbalance caused by chronic hyperglycaemia and hyperlipidaemia severely affects mitochondrial metabolism, leading to the development of impaired glucose-induced insulin secretion in type 2 diabetes. It appears that the anaplerotic enzyme pyruvate carboxylase participates directly or indirectly in several metabolic pathways which are important for glucose-induced insulin secretion, including: the pyruvate/malate cycle, the pyruvate/citrate cycle, the pyruvate/isocitrate cycle and glutamate-dehydrogenase-catalysed alpha-ketoglutarate production. These four pathways enable 'shuttling' or 'recycling' of these intermediate(s) into and out of mitochondrion, allowing continuous production of intracellular messenger(s). The purpose of this review is to present an account of recent progress in this area of central importance in the realm of diabetes and obesity research.
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Affiliation(s)
- S Jitrapakdee
- Molecular Metabolism Research Group, Department of Biochemistry, Faculty of Science, Mahidol University, Rama 6 Road, Phya-Thai, Bangkok 10400, Thailand.
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40
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Stark R, Pasquel F, Turcu A, Pongratz RL, Roden M, Cline GW, Shulman GI, Kibbey RG. Phosphoenolpyruvate cycling via mitochondrial phosphoenolpyruvate carboxykinase links anaplerosis and mitochondrial GTP with insulin secretion. J Biol Chem 2009; 284:26578-90. [PMID: 19635791 PMCID: PMC2785346 DOI: 10.1074/jbc.m109.011775] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 07/15/2009] [Indexed: 11/13/2022] Open
Abstract
Pancreatic beta-cells couple the oxidation of glucose to the secretion of insulin. Apart from the canonical K(ATP)-dependent glucose-stimulated insulin secretion (GSIS), there are important K(ATP)-independent mechanisms involving both anaplerosis and mitochondrial GTP (mtGTP). How mtGTP that is trapped within the mitochondrial matrix regulates the cytosolic calcium increases that drive GSIS remains a mystery. Here we have investigated whether the mitochondrial isoform of phosphoenolpyruvate carboxykinase (PEPCK-M) is the GTPase linking hydrolysis of mtGTP made by succinyl-CoA synthetase (SCS-GTP) to an anaplerotic pathway producing phosphoenolpyruvate (PEP). Although cytosolic PEPCK (PEPCK-C) is absent, PEPCK-M message and protein were detected in INS-1 832/13 cells, rat islets, and mouse islets. PEPCK enzymatic activity is half that of primary hepatocytes and is localized exclusively to the mitochondria. Novel (13)C-labeling strategies in INS-1 832/13 cells and islets measured substantial contribution of PEPCK-M to the synthesis of PEP. As high as 30% of PEP in INS-1 832/13 cells and 41% of PEP in rat islets came from PEPCK-M. The contribution of PEPCK-M to overall PEP synthesis more than tripled with glucose stimulation. Silencing the PEPCK-M gene completely inhibited GSIS underscoring its central role in mitochondrial metabolism-mediated insulin secretion. Given that mtGTP synthesized by SCS-GTP is an indicator of TCA flux that is crucial for GSIS, PEPCK-M is a strong candidate to link mtGTP synthesis with insulin release through anaplerotic PEP cycling.
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Affiliation(s)
| | | | - Adina Turcu
- From the Departments of Internal Medicine and
| | | | - Michael Roden
- the Institute for Clinical Diabetology, German Diabetes Center, 40225 Düsseldorf, Germany
| | | | - Gerald I. Shulman
- From the Departments of Internal Medicine and
- Cellular and Molecular Physiology and
- the Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520 and
| | - Richard G. Kibbey
- From the Departments of Internal Medicine and
- Cellular and Molecular Physiology and
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MacDonald MJ, Longacre MJ, Kendrick MA. Mitochondrial malic enzyme (ME2) in pancreatic islets of the human, rat and mouse and clonal insulinoma cells. Arch Biochem Biophys 2009; 488:100-4. [PMID: 19691144 DOI: 10.1016/j.abb.2009.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Despite interest in malic enzyme(ME)s in insulin cells, mitochondrial malic enzyme (ME2) has only been studied with estimates of mRNA or with mRNA knockdown. Because an mRNA's level does not necessarily reflect the level of its cognate enzyme, we designed a simple spectrophotometric enzyme assay to measure ME2 activity of insulin cells by utilizing the distinct kinetic properties of ME2. Mitochondrial ME2 uses either NAD or NADP as a cofactor, has a high Km for malate and is allosterically activated by fumarate and inhibited by ATP. Cytosolic ME (ME1) and the other mitochondrial ME (ME3) use only NADP as a cofactor and have lower Kms for malate. The assay easily showed for the first time that substantial ME2 activity is present in pancreatic islets of humans, rats and mice and INS-1 832/13 cells. ME2's presence was confirmed with immunoblotting. There was no evidence that ME3 is present in these tissues.
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Affiliation(s)
- Michael J MacDonald
- Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA.
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