1
|
Hansen GE, Gibson GE. The α-Ketoglutarate Dehydrogenase Complex as a Hub of Plasticity in Neurodegeneration and Regeneration. Int J Mol Sci 2022; 23:12403. [PMID: 36293260 PMCID: PMC9603878 DOI: 10.3390/ijms232012403] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/06/2022] [Accepted: 10/11/2022] [Indexed: 07/30/2023] Open
Abstract
Abnormal glucose metabolism is central to neurodegeneration, and considerable evidence suggests that abnormalities in key enzymes of the tricarboxylic acid (TCA) cycle underlie the metabolic deficits. Significant recent advances in the role of metabolism in cancer provide new insight that facilitates our understanding of the role of metabolism in neurodegeneration. Research indicates that the rate-limiting step of the TCA cycle, the α-ketoglutarate dehydrogenase complex (KGDHC) and its substrate alpha ketoglutarate (KG), serve as a signaling hub that regulates multiple cellular processes: (1) is the rate-limiting step of the TCA cycle, (2) is sensitive to reactive oxygen species (ROS) and produces ROS, (3) determines whether KG is used for energy or synthesis of compounds to support growth, (4) regulates the cellular responses to hypoxia, (5) controls the post-translational modification of hundreds of cell proteins in the mitochondria, cytosol, and nucleus through succinylation, (6) controls critical aspects of transcription, (7) modulates protein signaling within cells, and (8) modulates cellular calcium. The primary focus of this review is to understand how reductions in KGDHC are translated to pathologically important changes that underlie both neurodegeneration and cancer. An understanding of each role is necessary to develop new therapeutic strategies to treat neurodegenerative disease.
Collapse
Affiliation(s)
- Grace E. Hansen
- Department of Biology, University of Massachusetts, Lowell, MA 01852, USA
| | - Gary E. Gibson
- Weill Cornell Medicine, Brain and Mind Research Institute, Burke Neurological Institute, White Plains, NY 10605, USA
| |
Collapse
|
2
|
Lee I, Yang NC. Using Taguchi Method to Determine the Optimum Conditions for Synthesizing Parapyruvate. Molecules 2022; 27:molecules27061870. [PMID: 35335234 PMCID: PMC8954423 DOI: 10.3390/molecules27061870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 02/01/2023] Open
Abstract
The synthesis of parapyruvate is important for the analysis of the content in the pyruvate supplements and the study of aging-related neurodegenerative diseases. However, the pure parapyruvate crystal is not, as yet, commercially available. In this study, we applied the Taguchi's L9 orthogonal array to investigate the optimal conditions for the preparation of the pure parapyruvate by the alkaline treatment of the pyruvic acid and then followed it with the solvent crystallization steps. We were also interested in revealing the major factors that affect the yield for the synthesized pure parapyruvate crystals. In addition, the parapyruvate-inhibited enzyme kinetic of α-ketoglutarate dehydrogenase complex (KGDHC) was also investigated. We found that the pure parapyruvate could be obtained in combination with an alkaline treatment and two solvent crystallization steps. The main factors affecting the yield of the pure parapyruvate were the concentration of the pyruvic acid (the reactant), the pH of the alkali treatment, the type of solvent used for the crystallization and the volume ratio of solvent used for crystallization. Finally, the optimal conditions could prepare parapyruvate crystals with a high purity of 99.8% and a high yield of 72.8%. In addition, the results demonstrate that parapyruvate is a reversibly competitive inhibitor for KGDHC.
Collapse
Affiliation(s)
- Inn Lee
- Department of Nutrition, Chung Shan Medical University, Taichung 402, Taiwan;
| | - Nae-Cherng Yang
- Department of Nutrition, Chung Shan Medical University, Taichung 402, Taiwan;
- Department of Nutrition, Chung Shan Medical University Hospital, Taichung 402, Taiwan
- Correspondence: ; Tel.: +886-4-2473-0022; Fax: +886-4-2324-8175
| |
Collapse
|
3
|
Increasing Inhibition of the Rat Brain 2-Oxoglutarate Dehydrogenase Decreases Glutathione Redox State, Elevating Anxiety and Perturbing Stress Adaptation. Pharmaceuticals (Basel) 2022; 15:ph15020182. [PMID: 35215295 PMCID: PMC8875720 DOI: 10.3390/ph15020182] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/28/2022] [Accepted: 01/28/2022] [Indexed: 12/10/2022] Open
Abstract
Specific inhibitors of mitochondrial 2-oxoglutarate dehydrogenase (OGDH) are administered to animals to model the downregulation of the enzyme as observed in neurodegenerative diseases. Comparison of the effects of succinyl phosphonate (SP, 0.02 mmol/kg) and its uncharged precursor, triethyl succinyl phosphonate (TESP, 0.02 and 0.1 mmol/kg) reveals a biphasic response of the rat brain metabolism and physiology to increasing perturbation of OGDH function. At the low (TE)SP dose, glutamate, NAD+, and the activities of dehydrogenases of 2-oxoglutarate and malate increase, followed by their decreases at the high TESP dose. The complementary changes, i.e., an initial decrease followed by growth, are demonstrated by activities of pyruvate dehydrogenase and glutamine synthetase, and levels of oxidized glutathione and citrulline. While most of these indicators return to control levels at the high TESP dose, OGDH activity decreases and oxidized glutathione increases, compared to their control values. The first phase of metabolic perturbations does not cause significant physiological changes, but in the second phase, the ECG parameters and behavior reveal decreased adaptability and increased anxiety. Thus, lower levels of OGDH inhibition are compensated by the rearranged metabolic network, while the increased levels induce a metabolic switch to a lower redox state of the brain, associated with elevated stress of the animals.
Collapse
|
4
|
Thiamine as a Possible Neuroprotective Strategy in Neonatal Hypoxic-Ischemic Encephalopathy. Antioxidants (Basel) 2021; 11:antiox11010042. [PMID: 35052546 PMCID: PMC8772822 DOI: 10.3390/antiox11010042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 02/08/2023] Open
Abstract
On the basis that similar biochemical and histological sequences of events occur in the brain during thiamine deficiency and hypoxia/ischemia related brain damage, we have planned this review to discuss the possible therapeutic role of thiamine and its derivatives in the management of neonatal hypoxic-ischemic encephalopathy (HIE). Among the many benefits, thiamine per se as antioxidant, given intravenously (IV) at high doses, defined as dosage greater than 100 mg IV daily, should counteract the damaging effects of reactive oxygen and nitrogen species in the brain, including the reaction of peroxynitrite with the tyrosine residues of the major enzymes involved in intracellular glucose metabolism, which plays a key pathophysiological role in HIE in neonates. Accordingly, it is conceivable that, in neonatal HIE, the blockade of intracellular progressive oxidative stress and the rescue of mitochondrial function mediated by thiamine and its derivatives can lead to a definite neuroprotective effect. Because therapeutic hypothermia and thiamine may both act on the latent period of HIE damage, a synergistic effect of these therapeutic strategies is likely. Thiamine treatment may be especially important in mild HIE and in areas of the world where there is limited access to expensive hypothermia equipment.
Collapse
|
5
|
Computer-Aided Drug Discovery Identifies Alkaloid Inhibitors of Parkinson's Disease Associated Protein, Prolyl Oligopeptidase. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:6687572. [PMID: 33897801 PMCID: PMC8052153 DOI: 10.1155/2021/6687572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/25/2020] [Accepted: 02/19/2021] [Indexed: 01/18/2023]
Abstract
Parkinson's disease is a common neurodegenerative disorder marked by the accumulation of the protein alpha synuclein. Studies have indicated the role of prolyl oligopeptidase (POP), a serine protease, in alpha synuclein accumulation. Therefore, POP emerges as an attractive medicinal target. Traditionally, most of the early medicines have been plant-based owing to their ready availability and negligible side effects. Alkaloids owing to their neurotransmitter modulatory, anti-amyloid, anti-oxidant, and anti-inflammatory activities have shown potential in neurodegenerative disease. In this work, we computationally evaluated alkaloid class of phytochemicals for their therapeutic efficacy against POP. Alkaloids were retrieved from the publically available database, Chemical Entities of Biological Interest (ChEBI), and screened for their drug likeness (Lipinski's rule of 5) and absorption, distribution, metabolism, and excretion, and toxicity (ADMET) in Discovery Studio by ensuring parameters suitable for a central nervous system disease such as blood-brain barrier (BBB) level set to ≤2, absorption level set to 0 and solubility level permitted set to 2, 3, or 4. Next, molecular docking was performed to learn about the affinity of the filtered alkaloids with the POP. Subsequently, molecular dynamic simulations were conducted to assess the reliability and stability of the alkaloid-protein complex. Our study identified metergoline, pipercallosine, celacinnine, lobeline, cystodytin G, lycoperine A, hookerianamide J, and martefragin A as putative lead compounds against POP. Among these, metergoline, pipercallosine, hookerianamide J, and lobeline showed the most promising results. These compounds demonstrated better or equivalent molecular docking scores in comparison to three POP inhibitors that had reached clinical trials, i.e., Z-321, S-17092, and JTP-4819. MD simulations indicated that these compounds remained intact at the active site while adhering to the binding mode and interaction patterns as that of the reported inhibitors. The research conducted here, therefore, provides evidence for conducting in vitro POP inhibitory studies of these newly identified plant-based POP inhibitors.
Collapse
|
6
|
Salimi M, Sadeghimahalli F, Shaerzadeh F, Khodagholi F, Zardooz H. Early-life stress altered pancreatic Krebs cycle-related enzyme activities in response to young adulthood physical and psychological stress in male rat offspring. Horm Mol Biol Clin Investig 2020; 42:19-27. [PMID: 33781007 DOI: 10.1515/hmbci-2020-0063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/14/2020] [Indexed: 01/06/2023]
Abstract
OBJECTIVES Early-life stress (ELS) increases the risk of metabolic disorders in later life. The present study investigated the ELS effect on pancreatic pyruvate dehydrogenase (PDH) protein level, α-ketoglutarate dehydrogenase (α-KGDH), and aconitase activities as metabolic enzymes in response to young adulthood stress in male rat offspring. METHODS Male Wistar rats were divided into six groups: Control, early life stress (Early STR), young adult foot-shock stress (Y. adult F-SH STR), early + young adult foot-shock stress (Early + Y. adult F-SH STR), young adult psychological stress (Y. adult Psy STR) and early + young adult psychological stress (Early + Y. adult Psy STR). Stress was induced by a communication box at 2 weeks of age and young adulthood for five consecutive days. The blood samples were collected in young adult rats, then pancreases were removed to measure its PDH protein level and aconitase and α-KGDH activities. RESULTS In ELS animals, applying foot-shock stress in young adulthood increased PDH protein level, decreased α-KGDH and aconitase activities, and increased plasma glucose, insulin, and corticosterone concentrations. However, exposure to young adulthood psychological stress only decreased α-KGDH and aconitase activities. CONCLUSIONS It seems that ELS altered metabolic response to young adulthood stress through changes of Krebs cycle-related enzymes activities, though the type of adulthood stress was determinant.
Collapse
Affiliation(s)
- Mina Salimi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Forouzan Sadeghimahalli
- Department of Physiology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Fatemeh Shaerzadeh
- Department of Neuroscience, University of Florida, Gainesville, Florida, USA
| | - Fariba Khodagholi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Homeira Zardooz
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| |
Collapse
|
7
|
Dobolyi A, Bago A, Palkovits M, Nemeria NS, Jordan F, Doczi J, Ambrus A, Adam-Vizi V, Chinopoulos C. Exclusive neuronal detection of KGDHC-specific subunits in the adult human brain cortex despite pancellular protein lysine succinylation. Brain Struct Funct 2020; 225:639-667. [PMID: 31982949 PMCID: PMC7046601 DOI: 10.1007/s00429-020-02026-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/11/2020] [Indexed: 12/31/2022]
Abstract
The ketoglutarate dehydrogenase complex (KGDHC) consists of three different subunits encoded by OGDH (or OGDHL), DLST, and DLD, combined in different stoichiometries. DLD subunit is shared between KGDHC and pyruvate dehydrogenase complex, branched-chain alpha-keto acid dehydrogenase complex, and the glycine cleavage system. Despite KGDHC's implication in neurodegenerative diseases, cell-specific localization of its subunits in the adult human brain has never been investigated. Here, we show that immunoreactivity of all known isoforms of OGDHL, OGDH, and DLST was detected exclusively in neurons of surgical human cortical tissue samples identified by their morphology and visualized by double labeling with fluorescent Nissl, while being absent from glia expressing GFAP, Aldhl1, myelin basic protein, Olig2, or IBA1. In contrast, DLD immunoreactivity was evident in both neurons and glia. Specificity of anti-KGDHC subunits antisera was verified by a decrease in staining of siRNA-treated human cancer cell lines directed against the respective coding gene products; furthermore, immunoreactivity of KGDHC subunits in human fibroblasts co-localized > 99% with mitotracker orange, while western blotting of 63 post-mortem brain samples and purified recombinant proteins afforded further assurance regarding antisera monospecificity. KGDHC subunit immunoreactivity correlated with data from the Human Protein Atlas as well as RNA-Seq data from the Allen Brain Atlas corresponding to genes coding for KGDHC components. Protein lysine succinylation, however, was immunohistochemically evident in all cortical cells; this was unexpected, because this posttranslational modification requires succinyl-CoA, the product of KGDHC. In view of the fact that glia of the human brain cortex lack succinate-CoA ligase, an enzyme producing succinyl-CoA when operating in reverse, protein lysine succinylation in these cells must exclusively rely on propionate and/or ketone body metabolism or some other yet to be discovered pathway encompassing succinyl-CoA.
Collapse
Affiliation(s)
- Arpad Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eotvos Lorand University, Budapest, 1117, Hungary
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Attila Bago
- National Institute of Neurosurgery, Budapest, 1145, Hungary
| | - Miklos Palkovits
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eotvos Lorand University, Budapest, 1117, Hungary
| | - Natalia S Nemeria
- Department of Chemistry, Rutgers University, Newark, NJ, 07102-1811, USA
| | - Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ, 07102-1811, USA
| | - Judit Doczi
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
| | - Attila Ambrus
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
- MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary
- MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, 1094, Hungary
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary.
| |
Collapse
|
8
|
Ronowska A, Szutowicz A, Bielarczyk H, Gul-Hinc S, Klimaszewska-Łata J, Dyś A, Zyśk M, Jankowska-Kulawy A. The Regulatory Effects of Acetyl-CoA Distribution in the Healthy and Diseased Brain. Front Cell Neurosci 2018; 12:169. [PMID: 30050410 PMCID: PMC6052899 DOI: 10.3389/fncel.2018.00169] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/31/2018] [Indexed: 12/25/2022] Open
Abstract
Brain neurons, to support their neurotransmitter functions, require a several times higher supply of glucose than non-excitable cells. Pyruvate, the end product of glycolysis, through pyruvate dehydrogenase complex reaction, is a principal source of acetyl-CoA, which is a direct energy substrate in all brain cells. Several neurodegenerative conditions result in the inhibition of pyruvate dehydrogenase and decrease of acetyl-CoA synthesis in mitochondria. This attenuates metabolic flux through TCA in the mitochondria, yielding energy deficits and inhibition of diverse synthetic acetylation reactions in all neuronal sub-compartments. The acetyl-CoA concentrations in neuronal mitochondrial and cytoplasmic compartments are in the range of 10 and 7 μmol/L, respectively. They appear to be from 2 to 20 times lower than acetyl-CoA Km values for carnitine acetyltransferase, acetyl-CoA carboxylase, aspartate acetyltransferase, choline acetyltransferase, sphingosine kinase 1 acetyltransferase, acetyl-CoA hydrolase, and acetyl-CoA acetyltransferase, respectively. Therefore, alterations in acetyl-CoA levels alone may significantly change the rates of metabolic fluxes through multiple acetylation reactions in brain cells in different physiologic and pathologic conditions. Such substrate-dependent alterations in cytoplasmic, endoplasmic reticulum or nuclear acetylations may directly affect ACh synthesis, protein acetylations, and gene expression. Thereby, acetyl-CoA may regulate the functional and adaptative properties of neuronal and non-neuronal brain cells. The excitotoxicity-evoked intracellular zinc excess hits several intracellular targets, yielding the collapse of energy balance and impairment of the functional and structural integrity of postsynaptic cholinergic neurons. Acute disruption of brain energy homeostasis activates slow accumulation of amyloid-β1-42 (Aβ). Extra and intracellular oligomeric deposits of Aβ affect diverse transporting and signaling pathways in neuronal cells. It may combine with multiple neurotoxic signals, aggravating their detrimental effects on neuronal cells. This review presents evidences that changes of intraneuronal levels and compartmentation of acetyl-CoA may contribute significantly to neurotoxic pathomechanisms of different neurodegenerative brain disorders.
Collapse
Affiliation(s)
- Anna Ronowska
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Andrzej Szutowicz
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Hanna Bielarczyk
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Sylwia Gul-Hinc
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Joanna Klimaszewska-Łata
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Aleksandra Dyś
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Marlena Zyśk
- Department of Laboratory Medicine, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | | |
Collapse
|
9
|
Yan R, Xu H, Fu X. Salidroside protects hypoxia-induced injury by up-regulation of miR-210 in rat neural stem cells. Biomed Pharmacother 2018; 103:1490-1497. [PMID: 29864934 DOI: 10.1016/j.biopha.2018.04.184] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 10/17/2022] Open
Abstract
Neonatal brain hypoxia is a disease that affects the nervous system in children. Salidroside is a compound that has an anti-hypoxic effect, but the mechanism of salidroside in neonatal cerebral hypoxia is unclear. Hence, we investigated the regulatory effect and mechanism of salidroside on hypoxic-induced injury of neural stem cells (NSCs). NSCs derived from embryo 14 Sprague-Dawley rats were treated by hypoxia, followed by the treatment of 0.8 mM salidroside. The expression levels of miR-210 and BTG3 in NSCs were altered by transfection. Cell viability and apoptosis were examined by CCK-8 and flow cytometry analysis. qRT-PCR and Western blot were performed to assess the expression changes of miR-210, BTG3, apoptosis-related factors and core factors in PI3K/AKT/mTOR pathway. We found that hypoxia induced an apoptosis-dependent death in NSCs. Salidroside exerted bFGF-like effect, as it alleviated hypoxia-induced viability impairment and apoptosis in NSCs. Further studies showed that hypoxia plus salidroside elevated miR-210 expression, and the protective actions of salidroside on hypoxia-modulated death in NSCs were attenuated by miR-210 suppression, while were enhanced by miR-210 overexpression. Besides, BTG3 was negatively regulated by miR-210. Overexpression of BTG3 inhibited the activation of PI3K/AKT/mTOR signaling pathway; of contrast, suppression of BTG3 promoted it. To conclude, this study provide in vitro evidence that salidroside protected NSCs against hypoxia-induced injury by up-regulation of miR-210, which in turn inhibited the expression of BTG3 and activated PI3K/AKT/mTOR signaling pathway.
Collapse
Affiliation(s)
- Rui Yan
- Department of Children Rehabilitation, Women & Children's Health Care Hospital of Linyi, Linyi 276016, Shandong, China
| | - Hua Xu
- Children's Hospital of Kaifeng City, Kaifeng 475000, Henan, China
| | - Xiaoxiang Fu
- Department of Child Health Care, Women & Children's Health Care Hospital of Linyi, Linyi 276016, Shandong, China.
| |
Collapse
|
10
|
Sandhir R, Halder A, Sunkaria A. Mitochondria as a centrally positioned hub in the innate immune response. Biochim Biophys Acta Mol Basis Dis 2016; 1863:1090-1097. [PMID: 27794419 DOI: 10.1016/j.bbadis.2016.10.020] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 10/21/2016] [Accepted: 10/22/2016] [Indexed: 12/28/2022]
Abstract
Mitochondria are vital organelles involved in numerous cellular functions ranging from energy metabolism to cell survival. Emerging evidence suggests that mitochondria provide a platform for signaling pathways involved in innate immune response. Mitochondrial ROS (mtROS) production, mitochondrial DNA (mtDNA) release, mitochondrial antiviral signaling protein (MAVS) are key triggers in the activation of innate immune response following variety of stress signals that include infection, tissue damage and metabolic dysregulation. The process is mediated through pattern recognition receptors (PRRs) that consist of retinoic acid inducible gene like receptors (RLRs), c-type lectin receptors (CLRs), toll type receptors (TLRs) and nuclear oligomerization-domain like receptors (NLRs). These signals converge to form a multiprotein complex called inflammasome that leads to caspase-1 activation to promote processing of precursor cytokines (pro-IL1β and pro-IL-18) to active cytokines (IL-1β and IL-18). It appears that mitochondria induced inflammasome activation contributes to inflammatory process in many diverse disorders. Therefore, strategies aimed at modulating mitochondria mediated inflammasome activation might be beneficial in many pathophysiological conditions. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.
Collapse
Affiliation(s)
- Rajat Sandhir
- Department of Biochemistry, Panjab University, Chandigarh, India.
| | - Avishek Halder
- Department of Biochemistry, Panjab University, Chandigarh, India
| | - Aditya Sunkaria
- Department of Biochemistry, Panjab University, Chandigarh, India
| |
Collapse
|
11
|
Pahrudin Arrozi A, Wan Ngah WZ, Mohd Yusof YA, Ahmad Damanhuri MH, Makpol S. Antioxidant modulation in restoring mitochondrial function in neurodegeneration. Int J Neurosci 2016; 127:218-235. [PMID: 27074540 DOI: 10.1080/00207454.2016.1178261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Alzheimer's disease (AD) and Parkinson's disease (PD) are the leading causes of disability associated with neurodegeneration worldwide. These diseases are influenced by multiple genetic and environmental factors and share similar mechanisms as both are characterized by accumulation and aggregation of misfolded proteins - amyloid-beta (Aβ) in AD and α-synuclein in PD. Over the past decade, increasing evidence has shown that mitochondrial dysfunction and the generation of reactive oxygen species (ROS) are involved in the pathology of these diseases, and the contributions of these defects to the cellular and molecular changes that eventually cause neuronal death have been explored. Using mitochondrial protective agents, such as antioxidants, to combat ROS provides a new strategy for neurodegenerative treatment. In this review, we highlight the potential of multiple types of antioxidants, including vitamins, phytochemicals, fatty acids and minerals, as well as synthetic antioxidants specifically targeting the mitochondria, which can restore mitochondrial function, in the treatment of neurodegenerative disorders at both the pre-clinical and clinical stages by focusing on AD and PD.
Collapse
Affiliation(s)
- Aslina Pahrudin Arrozi
- a Department of Biochemistry , Universiti Kebangsaan Malaysia Medical Center , Kuala Lumpur , Malaysia
| | - Wan Zurinah Wan Ngah
- a Department of Biochemistry , Universiti Kebangsaan Malaysia Medical Center , Kuala Lumpur , Malaysia
| | - Yasmin Anum Mohd Yusof
- a Department of Biochemistry , Universiti Kebangsaan Malaysia Medical Center , Kuala Lumpur , Malaysia
| | | | - Suzana Makpol
- a Department of Biochemistry , Universiti Kebangsaan Malaysia Medical Center , Kuala Lumpur , Malaysia
| |
Collapse
|
12
|
Sodium restriction on top of renin–angiotensin–aldosterone system blockade increases circulating levels of N-acetyl-seryl-aspartyl-lysyl-proline in chronic kidney disease patients. J Hypertens 2013; 31:2425-32. [DOI: 10.1097/hjh.0b013e328364f5de] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
13
|
Acetyl-CoA the key factor for survival or death of cholinergic neurons in course of neurodegenerative diseases. Neurochem Res 2013; 38:1523-42. [PMID: 23677775 PMCID: PMC3691476 DOI: 10.1007/s11064-013-1060-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 04/19/2013] [Accepted: 04/22/2013] [Indexed: 12/24/2022]
Abstract
Glucose-derived pyruvate is a principal source of acetyl-CoA in all brain cells, through pyruvate dehydogenase complex (PDHC) reaction. Cholinergic neurons like neurons of other transmitter systems and glial cells, utilize acetyl-CoA for energy production in mitochondria and diverse synthetic pathways in their extramitochondrial compartments. However, cholinergic neurons require additional amounts of acetyl-CoA for acetylcholine synthesis in their cytoplasmic compartment to maintain their transmitter functions. Characteristic feature of several neurodegenerating diseases including Alzheimer’s disease and thiamine diphosphate deficiency encephalopathy is the decrease of PDHC activity correlating with cholinergic deficits and losses of cognitive functions. Such conditions generate acetyl-CoA deficits that are deeper in cholinergic neurons than in noncholinergic neuronal and glial cells, due to its additional consumption in the transmitter synthesis. Therefore, any neuropathologic conditions are likely to be more harmful for the cholinergic neurons than for noncholinergic ones. For this reason attempts preserving proper supply of acetyl-CoA in the diseased brain, should attenuate high susceptibility of cholinergic neurons to diverse neurodegenerative conditions. This review describes how common neurodegenerative signals could induce deficts in cholinergic neurotransmission through suppression of acetyl-CoA metabolism in the cholinergic neurons.
Collapse
|
14
|
Starkov AA. An update on the role of mitochondrial α-ketoglutarate dehydrogenase in oxidative stress. Mol Cell Neurosci 2012; 55:13-6. [PMID: 22820180 DOI: 10.1016/j.mcn.2012.07.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/22/2012] [Accepted: 07/10/2012] [Indexed: 01/06/2023] Open
Abstract
The activity of mitochondrial alpha-ketoglutarate dehydrogenase complex (KGDHC) is severely reduced in human pathologies where oxidative stress is traditionally thought to play an important role, such as familial and sporadic forms of Alzheimer's disease and other age-related neurodegenerative diseases. This minireview is focused on substantial data that were accumulated over the last 2 decades to support the concept that KGDHC can be a primary mitochondrial target of oxidative stress and at the same time a key contributor to it by producing reactive oxygen species. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
Collapse
Affiliation(s)
- Anatoly A Starkov
- Department of Neurology and Neuroscience, Weill Medical College, Cornell University, New York, NY 10021, USA.
| |
Collapse
|
15
|
Kinetic Modeling of the Mitochondrial Energy Metabolism of Neuronal Cells: The Impact of Reduced α-Ketoglutarate Dehydrogenase Activities on ATP Production and Generation of Reactive Oxygen Species. Int J Cell Biol 2012; 2012:757594. [PMID: 22719765 PMCID: PMC3376505 DOI: 10.1155/2012/757594] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/11/2012] [Indexed: 11/17/2022] Open
Abstract
Reduced activity of brain α-ketoglutarate dehydrogenase complex (KGDHC) occurs in a number of neurodegenerative diseases like Parkinson's disease and Alzheimer's disease. In order to quantify the relation between diminished KGDHC activity and the mitochondrial ATP generation, redox state, transmembrane potential, and generation of reactive oxygen species (ROS) by the respiratory chain (RC), we developed a detailed kinetic model. Model simulations revealed a threshold-like decline of the ATP production rate at about 60% inhibition of KGDHC accompanied by a significant increase of the mitochondrial membrane potential. By contrast, progressive inhibition of the enzyme aconitase had only little impact on these mitochondrial parameters. As KGDHC is susceptible to ROS-dependent inactivation, we also investigated the reduction state of those sites of the RC proposed to be involved in ROS production. The reduction state of all sites except one decreased with increasing degree of KGDHC inhibition suggesting an ROS-reducing effect of KGDHC inhibition. Our model underpins the important role of reduced KGDHC activity in the energetic breakdown of neuronal cells during development of neurodegenerative diseases.
Collapse
|
16
|
Chen YW, Liu BW, Zhang YJ, Chen YW, Dong GF, Ding XD, Xu LM, Pat B, Fan JG, Li DG. Preservation of basal AcSDKP attenuates carbon tetrachloride-induced fibrosis in the rat liver. J Hepatol 2010; 53:528-36. [PMID: 20646773 DOI: 10.1016/j.jhep.2010.03.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 03/15/2010] [Accepted: 03/31/2010] [Indexed: 01/22/2023]
Abstract
BACKGROUND & AIMS N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) is an endogenous tetrapeptide which has antifibrogenic effects at physiological concentrations in various tissues. AcSDKP is produced locally in the liver, however, little is known about its biological effect in this organ. We hypothesize that basal levels of endogenous AcSDKP decrease during the development of liver fibrosis and preservation of basal AcSDKP attenuates liver fibrosis. METHODS Endogenous levels of AcSDKP in the liver were measured by enzyme immunoassay after 2, 6, and 10 weeks of carbon tetrachloride (CCl(4))-induced liver fibrosis in rats. Subcutaneous osmotic pump infusion of vehicle or AcSDKP (800 microg/kg/day) was administered to CCl(4)-treated rats for 8 weeks to study the effect of exogenous AcSDKP on liver fibrosis. The effect of AcSDKP on profibrogenic properties of hepatic stellate cells was studied in vitro. RESULTS Endogenous AcSDKP was significantly decreased in the liver of CCl(4)-treated rats. Chronic AcSDKP infusion preserved basal levels of AcSDKP and reduced liver injury, inflammation, fibrosis, and profibrogenic transforming growth factor-beta signaling. This was demonstrated by decreased aminotransferase serum levels, CD45 positive cells, collagen accumulation, alpha-smooth muscle actin positivity, transforming growth factor-beta1, phosphorylated Smad2/3 protein, increased bone morphogenetic protein-7, and phosphorylated Smad1/5/8. Further, AcSDKP exerts antifibrogenic effects on hepatic stellate cells (HSCs) by downregulation of HSC activation in vitro. CONCLUSIONS Maintaining physiological levels of AcSDKP is critical in negatively regulating the development of fibrosis in chronic liver injury. Preservation of AcSDKP may be a useful therapeutic approach in the management of liver fibrosis.
Collapse
Affiliation(s)
- Yuan-Wen Chen
- Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Effects of memantine on soluble Αβ25-35-induced changes in peptidergic and glial cells in Alzheimer's disease model rat brain regions. Neuroscience 2009; 164:1199-209. [DOI: 10.1016/j.neuroscience.2009.08.063] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 08/18/2009] [Accepted: 08/28/2009] [Indexed: 11/21/2022]
|
18
|
Gibson GE, Starkov A, Blass JP, Ratan RR, Beal MF. Cause and consequence: mitochondrial dysfunction initiates and propagates neuronal dysfunction, neuronal death and behavioral abnormalities in age-associated neurodegenerative diseases. Biochim Biophys Acta Mol Basis Dis 2009; 1802:122-34. [PMID: 19715758 DOI: 10.1016/j.bbadis.2009.08.010] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 08/14/2009] [Accepted: 08/17/2009] [Indexed: 12/31/2022]
Abstract
Age-related neurodegenerative diseases are associated with mild impairment of oxidative metabolism and accumulation of abnormal proteins. Within the cell, the mitochondria appears to be a dominant site for initiation and propagation of disease processes. Shifts in metabolism in response to mild metabolic perturbations may decrease the threshold for irreversible injury in response to ordinarily sublethal metabolic insults. Mild impairment of metabolism accrue from and lead to increased reactive oxygen species (ROS). Increased ROS change cell signaling via post-transcriptional and transcriptional changes. The cause and consequences of mild impairment of mitochondrial metabolism is one focus of this review. Many experiments in tissues from humans support the notion that oxidative modification of the alpha-ketoglutarate dehydrogenase complex (KGDHC) compromises neuronal energy metabolism and enhances ROS production in Alzheimer's Disease (AD). These data suggest that cognitive decline in AD derives from the selective tricarboxylic acid (TCA) cycle abnormalities. By contrast in Huntington's Disease (HD), a movement disorder with cognitive features distinct form AD, complex II+III abnormalities may dominate. These distinct mitochondrial abnormalities culminate in oxidative stress, energy dysfunction, and aberrant homeostasis of cytosolic calcium. Cytosolic calcium, elevations even only transiently, leads to hyperactivity of a number of enzymes. One calcium-activated enzyme with demonstrated pathophysiological import in HD and AD is transglutaminase (TGase). TGase is a crosslinking enzymes that can modulate transcription, inactivate metabolic enzymes, and cause aggregation of critical proteins. Recent data indicate that TGase can silence expression of genes involved in compensating for metabolic stress. Altogether, our results suggest that increasing KGDHC via inhibition of TGase or via a host of other strategies to be described would be effective therapeutic approaches in age-associated neurodegenerative diseases.
Collapse
Affiliation(s)
- Gary E Gibson
- Department of Neurology and Neuroscience, Weill Cornell Medical College of Cornell University at Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA.
| | | | | | | | | |
Collapse
|
19
|
Qiu L, Wang H, Xia X, Zhou H, Xu Z. A construct with fluorescent indicators for conditional expression of miRNA. BMC Biotechnol 2008; 8:77. [PMID: 18840295 PMCID: PMC2569932 DOI: 10.1186/1472-6750-8-77] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 10/07/2008] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Transgenic RNAi holds promise as a simple, low-cost, and fast method for reverse genetics in mammals. It may be particularly useful for producing animal models for hypomorphic gene function. Inducible RNAi that permits spatially and temporally controllable gene silencing in vivo will enhance the power of transgenic RNAi approach. Furthermore, because microRNA (miRNA) targeting specific genes can be expressed simultaneously with protein coding genes, incorporation of fluorescent marker proteins can simplify the screening and analysis of transgenic RNAi animals. RESULTS We sought to optimally express a miRNA simultaneously with a fluorescent marker. We compared two construct designs. One expressed a red fluorescent protein (RFP) and a miRNA placed in its 3' untranslated region (UTR). The other expressed the same RFP and miRNA, but the precursor miRNA (pre-miRNA) coding sequence was placed in an intron that was inserted into the 3'-UTR. We found that the two constructs expressed comparable levels of miRNA. However, the intron-containing construct expressed a significantly higher level of RFP than the intron-less construct. Further experiments indicate that the 3'-UTR intron enhances RFP expression by its intrinsic gene-expression-enhancing activity and by eliminating the inhibitory effect of the pre-miRNA on the expression of RFP. Based on these findings, we incorporated the intron-embedded pre-miRNA design into a conditional expression construct that employed the Cre-loxP system. This construct initially expressed EGFP gene, which was flanked by loxP sites. After exposure to Cre recombinase, the transgene stopped EGFP expression and began expression of RFP and a miRNA, which silenced the expression of specific cellular genes. CONCLUSION We have designed and tested a conditional miRNA-expression construct and showed that this construct expresses both the marker genes strongly and can silence the target gene efficiently upon Cre-mediated induction of the miRNA expression. This construct can be used to increase the efficiency of making cell lines or transgenic animals that stably express miRNA targeting specific genes.
Collapse
Affiliation(s)
- Linghua Qiu
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
| | - Hongyan Wang
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
| | - Xugang Xia
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
- Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University Medical College, 508 JAH, 1020 Locust Avenue, Philadelphia, PA 19107, USA
| | - Hongxia Zhou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
- Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University Medical College, 508 JAH, 1020 Locust Avenue, Philadelphia, PA 19107, USA
| | - Zuoshang Xu
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
- Cell Biology, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
- Neuroscience Program, University of Massachusetts Medical School, 364 Plantation St, Worcester, MA 01605, USA
| |
Collapse
|
20
|
Shi Q, Xu H, Kleinman WA, Gibson GE. Novel functions of the alpha-ketoglutarate dehydrogenase complex may mediate diverse oxidant-induced changes in mitochondrial enzymes associated with Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2007; 1782:229-38. [PMID: 18206986 DOI: 10.1016/j.bbadis.2007.12.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 12/07/2007] [Accepted: 12/12/2007] [Indexed: 12/13/2022]
Abstract
Measures in autopsied brains from Alzheimer's Disease (AD) patients reveal a decrease in the activity of alpha-ketoglutarate dehydrogenase complex (KGDHC) and an increase in malate dehydrogenase (MDH) activity. The present experiments tested whether both changes could be caused by the common oxidant H(2)O(2) and to probe the mechanism underlying these changes. Since the response to H(2)O(2) is modified by the level of the E2k subunit of KGDHC, the interaction of MDH and KGDHC was studied in cells with varying levels of E2k. In cells with only 23% of normal E2k protein levels, one-hour treatment with H(2)O(2) decreased KGDHC and increased MDH activity as well as the mRNA level for both cytosolic and mitochondrial MDH. The increase in MDH did not occur in cells with 100% or 46% of normal E2k. Longer treatments with H(2)O(2) inhibited the activity of both enzymes. Glutathione is a major regulator of cellular redox state and can modify enzyme activities. H(2)O(2) converts reduced glutathione (GSH) to oxidized glutathione (GSSG), which reacts with protein thiols. Treatment of purified KGDHC with GSSG leads to glutathionylation of all three KGDHC subunits. Thus, cellular glutathione level was manipulated by two means to determine the effect on KGDHC and MDH activities. Both buthionine sulfoximine (BSO), which inhibits glutathione synthesis without altering redox state, and H(2)O(2) diminished glutathione to a similar level after 24 h. However, H(2)O(2), but not BSO, reduced KGDHC and MDH activities, and the reduction was greater in the E2k-23 line. These findings suggest that the E2k may mediate diverse responses of KGDHC and MDH to oxidants. In addition, the differential response of activities to BSO and H(2)O(2) together with the in vitro interaction of KGDHC with GSSG suggests that glutathionylation is one possible mechanism underlying oxidative stress-induced inhibition of the TCA cycle enzymes.
Collapse
Affiliation(s)
- Qingli Shi
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University/Burke Medical Research Institute, White Plains, New York 10605, USA
| | | | | | | |
Collapse
|
21
|
García-Horsman JA, Männistö PT, Venäläinen JI. On the role of prolyl oligopeptidase in health and disease. Neuropeptides 2007; 41:1-24. [PMID: 17196652 DOI: 10.1016/j.npep.2006.10.004] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 10/10/2006] [Accepted: 10/17/2006] [Indexed: 11/18/2022]
Abstract
Prolyl oligopeptidase (POP) is a serine peptidase which digests small peptide-like hormones, neuroactive peptides, and various cellular factors. Therefore, this peptidase has been implicated in many physiological processes as well as in some psychiatric disorders, most probably through interference in inositol cycle. Intense research has been performed to elucidate, on the one hand, the basic structure, ligand binding, and kinetic properties of POP, and on the other, the pharmacology of its inhibitors. There is fairly strong evidence of in vivo importance of POP on substance P, arginine vasopressin, thyroliberin and gonadoliberin metabolism. However, information about the biological relevance of POP is not yet conclusive. Evidence regarding the physiological role of POP is lacking, which is surprising considering that peptidase inhibitors have been exploited for drug development, some of which are currently in clinical trials as memory enhancers for the aged and in a variety of neurological disorders. Here we review the recent progress on POP research and evaluate the relevance of the peptidase in the metabolism of various neuropeptides. The recognition of novel forms and relatives of POP may improve our understanding of how this family of proteins functions in normal and in neuropathological conditions.
Collapse
Affiliation(s)
- J A García-Horsman
- Centro de Investigación Príncipe Felipe, Neurobiology, Av. Autopista del Saler 16, 46013 Valencia, Spain.
| | | | | |
Collapse
|
22
|
Brandt I, Scharpé S, Lambeir AM. Suggested functions for prolyl oligopeptidase: a puzzling paradox. Clin Chim Acta 2006; 377:50-61. [PMID: 17034776 DOI: 10.1016/j.cca.2006.09.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 08/29/2006] [Accepted: 09/01/2006] [Indexed: 10/24/2022]
Abstract
Prolyl oligopeptidase (PO, E.C. 3.4.21.26) is a post-proline cleaving enzyme with endopeptidase activity towards peptides not longer than 30 amino acids. It has been purified and characterized from various mammalian and bacterial sources, but despite its thorough enzymological and structural characterization, the exact function of PO remains obscure. Many investigations have addressed the physiological role of this enzyme, mainly by the use of specific PO inhibitors, activity measurements in clinical samples and (neuro)peptide degradation studies. From the combined results emerges a puzzling paradox: how can an intracellular, cytoplasmatic oligopeptidase affect not only the amount of extracellular neuropeptides but also signal transduction and secretion? This report provides a review of the literature on the suggested functions for PO, highlighting possible pitfalls and contradictions.
Collapse
Affiliation(s)
- Inger Brandt
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences University of Antwerp, Universiteitsplein 1, Blg S6 B-2610 Antwerp (Wilrijk), Belgium
| | | | | |
Collapse
|
23
|
Tretter L, Adam-Vizi V. Alpha-ketoglutarate dehydrogenase: a target and generator of oxidative stress. Philos Trans R Soc Lond B Biol Sci 2006; 360:2335-45. [PMID: 16321804 PMCID: PMC1569585 DOI: 10.1098/rstb.2005.1764] [Citation(s) in RCA: 298] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Alpha-ketoglutarate dehydrogenase (alpha-KGDH) is a highly regulated enzyme, which could determine the metabolic flux through the Krebs cycle. It catalyses the conversion of alpha-ketoglutarate to succinyl-CoA and produces NADH directly providing electrons for the respiratory chain. alpha-KGDH is sensitive to reactive oxygen species (ROS) and inhibition of this enzyme could be critical in the metabolic deficiency induced by oxidative stress. Aconitase in the Krebs cycle is more vulnerable than alpha-KGDH to ROS but as long as alpha-KGDH is functional NADH generation in the Krebs cycle is maintained. NADH supply to the respiratory chain is limited only when alpha-KGDH is also inhibited by ROS. In addition being a key target, alpha-KGDH is able to generate ROS during its catalytic function, which is regulated by the NADH/NAD+ ratio. The pathological relevance of these two features of alpha-KGDH is discussed in this review, particularly in relation to neurodegeneration, as an impaired function of this enzyme has been found to be characteristic for several neurodegenerative diseases.
Collapse
|
24
|
Chinopoulos C, Adam-Vizi V. Calcium, mitochondria and oxidative stress in neuronal pathology. Novel aspects of an enduring theme. FEBS J 2006; 273:433-50. [PMID: 16420469 DOI: 10.1111/j.1742-4658.2005.05103.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interplay among reactive oxygen species (ROS) formation, elevated intracellular calcium concentration and mitochondrial demise is a recurring theme in research focusing on brain pathology, both for acute and chronic neurodegenerative states. However, causality, extent of contribution or the sequence of these events prior to cell death is not yet firmly established. Here we review the role of the alpha-ketoglutarate dehydrogenase complex as a newly identified source of mitochondrial ROS production. Furthermore, based on contemporary reports we examine novel concepts as potential mediators of neuronal injury connecting mitochondria, increased [Ca2+]c and ROS/reactive nitrogen species (RNS) formation; specifically: (a) the possibility that plasmalemmal nonselective cationic channels contribute to the latent [Ca2+]c rise in the context of glutamate-induced delayed calcium deregulation; (b) the likelihood of the involvement of the channels in the phenomenon of 'Ca2+ paradox' that might be implicated in ischemia/reperfusion injury; and (c) how ROS/RNS and mitochondrial status could influence the activity of these channels leading to loss of ionic homeostasis and cell death.
Collapse
Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences, Szentagothai Knowledge Center, Budapest, Hungary
| | | |
Collapse
|
25
|
Ahmed MM, Arif M, Chikuma T, Kato T. Pentylenetetrazol-induced seizures affect the levels of prolyl oligopeptidase, thimet oligopeptidase and glial proteins in rat brain regions, and attenuation by MK-801 pretreatment. Neurochem Int 2005; 47:248-59. [PMID: 15985312 DOI: 10.1016/j.neuint.2005.04.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Revised: 04/20/2005] [Accepted: 04/21/2005] [Indexed: 11/27/2022]
Abstract
The regulatory mechanisms of neuropeptide-metabolizing enzymes often play a critical role in the pathogenesis of neuronal damage. A systemic administration of pentylenetetrazol (PTZ), an antagonist of GABA(A) receptor ion channel binding site, causes generalized epilepsy in an animal model. In the present study, we examined the involvement of prolyl oligopeptidase (POP), thimet oligopeptidase/neurolysin (EP 24.15/16) and glial proteins in PTZ-treated rat brain regions, and the suppressive effect of MK-801, a non-competitive NMDA receptor antagonist, pretreatment for their proteins. The activity of POP significantly decreased in the hippocampus at 30min and 3h, and in the frontal cortex at 3h after PTZ treatment, and pretreatment with MK-801 recovered the activity in the cortex at 3h. The activity of EP 24.15/16 significantly decreased in the hippocampus at 3h and 1 day, and in the cortex at 3h after the PTZ administration, whereas pretreatment with MK-801 recovered the change of the activity. The Western blot analysis of EP 24.15 showed significant decrease of the protein level in the hippocampus 3h after the PTZ treatment, whereas pretreatment with MK-801 recovered. The expression of GFAP and CD11b immunohistochemically increased in the hippocampus of the PTZ-treated rat as compared with controls. Pretreatment with MK-801 also recovered the GFAP and CD11b expression. These data suggest that PTZ-induced seizures of the rats cause indirect activation of glutamate NMDA receptors, then decrease POP and EP 24.15/16 enzyme activities and EP 24.15 immunoreactivity in the neuronal cells of the hippocampal formation. We speculate that changes of those peptidases in the brain may be related to the levels of the neuropeptides regulating PTZ-induced seizures.
Collapse
Affiliation(s)
- M Mahiuddin Ahmed
- Laboratory of Natural Information Science, Graduate School of Integrated Science, Yokohama City University, 22-2 Seto, Kanazawa-Ku, Yokohama 236-0027, Japan
| | | | | | | |
Collapse
|
26
|
Jeitner TM, Xu H, Gibson GE. Inhibition of the alpha-ketoglutarate dehydrogenase complex by the myeloperoxidase products, hypochlorous acid and mono-N-chloramine. J Neurochem 2005; 92:302-10. [PMID: 15663478 DOI: 10.1111/j.1471-4159.2004.02868.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Abstract alpha-Ketoglutarate dehydrogenase (KGDHC) complex activity is diminished in a number of neurodegenerative disorders and its diminution in Alzheimer Disease (AD) is thought to contribute to the major loss of cerebral energy metabolism that accompanies this disease. The loss of KGDHC activity appears to be predominantly due to post-translation modifications. Thiamine deficiency also results in decreased KGDHC activity and a selective neuronal loss. Recently, myeloperoxidase has been identified in the activated microglia of brains from AD patients and thiamine-deficient animals. Myeloperoxidase produces a powerful oxidant, hypochlorous acid that reacts with amines to form chloramines. The aim of this study was to investigate the ability of hypochlorous acid and chloramines to inhibit the activity of KGDHC activity as a first step towards investigating the role of myeloperoxidase in AD. Hypochlorous acid and mono-N-chloramine both inhibited purified and cellular KGDHC and the order of inhibition of the purified complex was hypochlorous acid (1x) > mono-N-chloramine (approximately 50x) > hydrogen peroxide (approximately 1,500). The inhibition of cellular KGDHC occurred with no significant loss of cellular viability at all exposure times that were examined. Thus, hypochlorous acid and chloramines have the potential to inactivate a major target in neurodegeneration.
Collapse
Affiliation(s)
- Thomas M Jeitner
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | | |
Collapse
|
27
|
Shi Q, Chen HL, Xu H, Gibson GE. Reduction in the E2k subunit of the alpha-ketoglutarate dehydrogenase complex has effects independent of complex activity. J Biol Chem 2005; 280:10888-96. [PMID: 15649899 DOI: 10.1074/jbc.m409064200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC) declines in brains of patients with several neurodegenerative diseases. KGDHC consists of multiple copies of E1k, E2k, and E3. E1k and E2k are unique to KGDHC and may have functions independent of the complex. The present study tested the consequences of different levels of diminished E2k mRNA on protein levels of the subunits, KGDHC activity, and physiological responses. Human embryonic kidney cells were stably transfected with an E2k sense or antisense expression vector. Sense control (E2k-mRNA-100) was compared with two clones in which the mRNA was reduced to 67% of control (E2k-mRNA-67) or to 30% of control (E2k-mRNA-30). The levels of the E2k protein in clones paralleled the reduction in mRNA, and E3 proteins were unaltered. Unexpectedly, the clone with the greatest reduction in E2k protein (E2k-mRNA-30) had a 40% increase in E1k protein. The activity of the complex was only 52% of normal in E2k-mRNA-67 clone, but was near normal (90%) in E2k-mRNA-30 clone. Subsequent experiments tested whether the physiological consequences of a reduction in E2k mRNA correlated more closely to E2k protein or to KGDHC activity. Growth rate, increased DCF-detectable reactive oxygen species, and cell death in response to added oxidant were proportional to E2k proteins, but not complex activity. These results were not predicted because subunits unique to KGDHC have never been manipulated in mammalian cells. These results suggest that in addition to its essential role in metabolism, the E2k component of KGDHC may have other novel roles.
Collapse
Affiliation(s)
- Qingli Shi
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University at Burke Medical Research Institute, White Plains, New York 10605, USA
| | | | | | | |
Collapse
|
28
|
Ahmed MM, Hoshino H, Chikuma T, Yamada M, Kato T. Effect of memantine on the levels of glial cells, neuropeptides, and peptide-degrading enzymes in rat brain regions of ibotenic acid-treated alzheimer's disease model. Neuroscience 2004; 126:639-49. [PMID: 15183513 DOI: 10.1016/j.neuroscience.2004.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2004] [Indexed: 02/06/2023]
Abstract
It has been implicated that glia activation plays a critical role in the progression of Alzheimer's disease (AD). However, the precise mechanism of glia activation is not clearly understood yet. In our present studies, we confirmed our previous results where change the levels of neuropeptides and peptidases in ibotenic acid (IBO) infusion into the rat nucleus basalis magnocellularis, an animal model of AD. Furthermore, we extended our study to investigate a possible protection effect of co-administration on the changes of neuropeptides, and neuronal and glial cells in IBO-infused rat brain by memantine treatment. The levels of substance P and somatostatin were decreased in the striatum and frontal cortex 1 week after IBO infusion, and recovered to the control level by memantine treatment, indicating the involvement of neuropeptides in AD pathology. Furthermore, the immunohistochemical and enzymatic studies of GFAP and CD 11b, and peptidylarginine deiminase, markers of glia, in the striatum and frontal cortex showed the increase in IBO-treated rat brain as compared with controls, while co-administration of memantine and IBO no increase of astrocytes and microglia activation was observed. The present biochemical and immunohistochemical results suggest that glia activation might play an important role to the pathology of AD, and correlate with the changes of neuropeptide levels in AD brain that is recovered by memantine treatment.
Collapse
Affiliation(s)
- M M Ahmed
- Laboratory of Natural Information Science, Graduate School of Integrated Science, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan
| | | | | | | | | |
Collapse
|
29
|
Abstract
Extensive, replicated evidence in patients in vivo and in Alzheimer (AD) tissues in vitro indicates that impaired brain metabolism is one of the cardinal and essentially invariable events in AD. The degree of impairment in brain metabolism is proportional to the degree of clinical disability, both in vivo and in vitro. The 'cerebrometabolic lesion' cannot be attributed to 'slower thinking' or 'brain atrophy', because of quantitative considerations and because the metabolic lesion precedes the development of neuropsychological abnormalities or decreases in brain mass detectable by modern imaging techniques. The causes of the cerebrometabolic lesion in AD are not well defined. Free radicals seem likely to be involved, including free radicals generated from Alzheimer amyloid. Thus, the importance of the cerebrometabolic lesion is entirely compatible with most versions of the widely accepted 'amyloid cascade hypothesis' of AD. A variety of plausible, redundantly documented mechanisms are compatible with the proposal that the cerebrometabolic lesion is a proximate cause of the clinical disability in AD. In agreement with these findings, recent attempts to treat the cerebrometabolic lesion in AD have given encouraging preliminary results. The cerebrometabolic lesion in AD deserves further study.
Collapse
Affiliation(s)
- John P Blass
- Dementia Research Service, Burke Medical Research Institute, Weill Medical College of Cornell University, 785 Mamaroneck Avenue, White Plains, NY 10708, USA.
| |
Collapse
|
30
|
Ahmed MM, Yamamoto M, Chikuma T, Rahman MK, Kato T. Dose-dependent effect of MK-801 on the levels of neuropeptides processing enzymes in rat brain regions. Neurosci Res 2003; 47:177-89. [PMID: 14512142 DOI: 10.1016/s0168-0102(03)00197-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The appropriate levels of neuropeptides and their processing enzyme activities are required to continue a normal cell life, and the dysfunction of these peptides and enzymes are responsible for many neuronal abnormalities. Systemic administration of (+) MK-801 (dizocilpine maleate), a noncompetitive N-methyl-[D]-aspartate (NMDA) receptor antagonist, causes both neuroprotective and neurotoxic activities depending on doses and conditions. In the present study, we investigated the dose dependent effect of (+) MK-801 on prolyl endopeptidase (PEP), endopeptidase EC 24.15 (EP 24.15) and beta-D-glucuronidase activities as well as the protein levels of EP 24.15 and neuron specific enolase (NSE) in the posterior cingulate/retrosplenial cortices (PC/RSC), hippocampus, frontal cortex and striatum of female rats 3 days after the treatment. The activity of PEP was significantly increased compared with controls (saline) in the PC/RSC at 1.0 and 5.0 mg/kg doses, and in the frontal cortex at 5.0 mg/kg dose. beta-D-Glucuronidase activity was dose-dependently increased in all brain regions examined. The activity of EP 24.15 was unchanged in all regions after the treatment, whereas the Western blot analysis for EP 24.15 showed the increased protein level in the PC/RSC. These results suggest that a low dose treatment with MK-801 causes neurotoxicity in the PC/RSC and hippocampus, and the high dose treatment causes neurotoxicity in all the brain regions examined.
Collapse
Affiliation(s)
- Md Mahiuddin Ahmed
- Laboratory of Natural Information Science, Graduate School of Integrated Science, Yokohama City University, 22-2 Seto, Kanazawa-Ku, Yokohama 236-0027, Japan
| | | | | | | | | |
Collapse
|
31
|
Agirregoitia N, Gil J, Ruiz F, Irazusta J, Casis L. Effect of Aging on Rat Tissue Peptidase Activities. J Gerontol A Biol Sci Med Sci 2003; 58:B792-7. [PMID: 14528034 DOI: 10.1093/gerona/58.9.b792] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The process of aging is known to involve alterations in the activity of peptidases and proteases. However, the precise changes in the activity of many peptidases in aged tissues have not yet been fully characterized, and both decreases and increases in both peptidase activity and peptide levels have been reported to occur during the aging process. In the present study, we measured the activity of several peptidases in selected tissues (brain cortex, brain stem, liver, kidney, heart, and lung) of the young adult (3 months old) and aged (18 months old and 22 months old) rat. The activities of prolyl endopeptidase, pyroglutamyl peptidase I, puromycin sensitive aminopeptidase, and aminopeptidase N were assayed using beta-naphthylamine aminoacidic derivatives as substrates. The activity of the soluble fractions of prolyl endopeptidase was found to be reduced in the lungs of aged animals, while reduced activity of soluble pyroglutamyl peptidase I and also aminopeptidase N was measured in the aged kidney and heart, respectively. In contrast, increased activity of particulate prolyl endopeptidase was measured in the brain stem of older animals. Since most of these changes can be correlated with known alterations in the levels of peptides controlled by each enzyme, the results of the present study indicate that the studied peptidases may play an important role in regulating tissue peptide levels during aging.
Collapse
Affiliation(s)
- Naiara Agirregoitia
- Department of Physiology, Medical School, University of the Basque Country, Bizkaia, Spain
| | | | | | | | | |
Collapse
|
32
|
Yamamoto M, Chikuma T, Kato T. Changes in the levels of neuropeptides and their metabolizing enzymes in the brain regions of nucleus basalis magnocellularis-lesioned rats. J Pharmacol Sci 2003; 92:400-10. [PMID: 12939525 DOI: 10.1254/jphs.92.400] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The regulation mechanism of the interrelation between neuropeptides and their metabolizing enzymes in in vivo tissues is still not clear. In the present report, we attempted to measure the levels of neuropeptides and their enzymes in the frontal cortex, hippocampus, and striatum of the rat that had been bilaterally lesioned by the infusion of ibotenic acid or amyloid beta-peptide 25 - 35 (Abeta25 - 35) into the nucleus basalis magnocellularis. In the drug-treated rats, at two weeks after the infusion, the decrease of somatostatin-like immunoreactivity (SS-LI) and the increase of cholecystokinin-8S-LI were found in some brain regions relative to vehicle-treated rats. The immunoreactivities of endopeptidase 24.15 and puromycin-sensitive aminopeptidase and the leucine aminopeptidase- and aminopeptidase B-like enzyme activities did not change in the three brain regions, suggesting that the levels of those peptide-degrading enzymes do not correlate with the changes of the neuropeptide levels. The decrease of subtilisin-like proprotein convertase (SPC)-like enzyme activity was found in the hippocampus of the Abeta25 - 35-treated rats. The SS mRNA level decreased in the hippocampus in parallel with decreases in the SS-LI level and SPC-like enzyme activity. The present data indicate that some of the neuropeptide-processing enzymes may contribute to the control of neuropeptide levels.
Collapse
Affiliation(s)
- Masaru Yamamoto
- Laboratory of Natural Information Science, Yokohama City University, Yokohama, Japan
| | | | | |
Collapse
|
33
|
Gibson GE, Kingsbury AE, Xu H, Lindsay JG, Daniel S, Foster OJF, Lees AJ, Blass JP. Deficits in a tricarboxylic acid cycle enzyme in brains from patients with Parkinson's disease. Neurochem Int 2003; 43:129-35. [PMID: 12620281 DOI: 10.1016/s0197-0186(02)00225-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Parkinson's disease (PD) is associated with mitochondrial dysfunction, specifically a deficiency of complex I of the electron transport chain. Most, although not all, studies indicate that this deficiency is limited to brain regions with neurodegeneration. The current studies tested for deficiencies in other mitochondrial components in PD brain in a neuropathologically unaffected region where the abnormality cannot be attributed to secondary effects of neurodegeneration. The activity of a key (and arguably rate-limiting) tricarboxylic acid cycle enzyme, the alpha-ketoglutarate dehydrogenase complex (KGDHC), was measured in the cerebellum of patients with PD. Activity in 19 PD brains was 50.5% of that in 18 controls matched for age, sex, post-mortem interval, and method of preservation (P<0.0019). The protein subunits of KGDHC were present in normal amounts in PD brains, indicating a relatively discrete abnormality in the enzyme. The activities of another mitochondrial enzyme, glutamate dehydrogenase (GDH), were normal in PD brains. These results demonstrate that specific reductions in KGDHC occur even in pathologically unaffected areas in PD, where the decline is unlikely to be a non-specific result of neurodegeneration. Reductions in the activity of this enzyme, if widespread in the brain, may predispose vulnerable regions to further damage.
Collapse
Affiliation(s)
- G E Gibson
- Weill Medical College of Cornell University, Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA.
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Huang HM, Zhang H, Xu H, Gibson GE. Inhibition of the alpha-ketoglutarate dehydrogenase complex alters mitochondrial function and cellular calcium regulation. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1637:119-26. [PMID: 12527416 DOI: 10.1016/s0925-4439(02)00222-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mitochondrial dysfunction occurs in many neurodegenerative diseases. The alpha-ketoglutarate dehydrogenase complex (KGDHC) catalyzes a key and arguably rate-limiting step of the tricarboxylic acid cycle (TCA). A reduction in the activity of the KGDHC occurs in brains and cells of patients with many of these disorders and may underlie the abnormal mitochondrial function. Abnormalities in calcium homeostasis also occur in fibroblasts from Alzheimer's disease (AD) patients and in cells bearing mutations that lead to AD. Thus, the present studies test whether the reduction of KGDHC activity can lead to the alterations in mitochondrial function and calcium homeostasis. alpha-Keto-beta-methyl-n-valeric acid (KMV) inhibits KGDHC activity in living N2a cells in a dose- and time-dependent manner. Surprisingly, concentration of KMV that inhibit in situ KGDHC by 80% does not alter the mitochondrial membrane potential (MMP). However, similar concentrations of KMV induce the release of cytochrome c from mitochondria into the cytosol, reduce basal [Ca(2+)](i) by 23% (P<0.005), and diminish the bradykinin (BK)-induced calcium release from the endoplasmic reticulum (ER) by 46% (P<0.005). This result suggests that diminished KGDHC activities do not lead to the Ca(2+) abnormalities in fibroblasts from AD patients or cells bearing PS-1 mutations. The increased release of cytochrome c with diminished KGDHC activities will be expected to activate other pathways including cell death cascades. Reductions in this key mitochondrial enzyme will likely make the cells more vulnerable to metabolic insults that promote cell death.
Collapse
Affiliation(s)
- Hsueh-Meei Huang
- Dementia Research Service, Weill Medical College of Cornell University, Burke Medical Res. Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA.
| | | | | | | |
Collapse
|
35
|
Laitinen KS, van Groen T, Tanila H, Venäläinen J, Männistö PT, Alafuzoff I. Brain prolyl oligopeptidase activity is associated with neuronal damage rather than beta-amyloid accumulation. Neuroreport 2001; 12:3309-12. [PMID: 11711876 DOI: 10.1097/00001756-200110290-00032] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Prolyl oligopeptidase (POP) have been suggested to participate in the pathogenesis of Alzheimer's disease (AD). In this study the activity of POP is evaluated in AD patients and in transgenic mice with substantial deposits of beta-amyloid (Abeta). In AD cases, the POP activity displayed a significant negative correlation with the scores of senile/neuritic plaques and neurofibrillary tangles but not with Abeta-load. The transgenic mice with high levels of Abeta did not have altered POP activity compared to wild type mice. Based on our results, the low POP activity in AD seems to be associated with neuronal degeneration rather than to Abeta accumulation.
Collapse
Affiliation(s)
- K S Laitinen
- Department of Pharmacology, University of Kuopio, P.O.Box 1627, Fin-70211, Kuopio, Finland
| | | | | | | | | | | |
Collapse
|
36
|
Gibson GE, Haroutunian V, Zhang H, Park LCH, Shi Q, Lesser M, Mohs RC, Sheu RKF, Blass JP. Mitochondrial damage in Alzheimer's disease varies with apolipoprotein E genotype. Ann Neurol 2001. [DOI: 10.1002/1531-8249(200009)48:3<297::aid-ana3>3.0.co;2-z] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
37
|
Blass JP, Sheu RK, Gibson GE. Inherent abnormalities in energy metabolism in Alzheimer disease. Interaction with cerebrovascular compromise. Ann N Y Acad Sci 2000; 903:204-21. [PMID: 10818509 DOI: 10.1111/j.1749-6632.2000.tb06370.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alzheimer disease (AD) is a form of the dementia syndrome. AD appears to have a variety of fundamental etiologies that lead to the neuropathological manifestations which define the disease. Patients who are at high risk to develop AD typically show impairments of cerebral metabolic rate in vivo even before they show any evidence of the clinical disease on neuropsychological, electrophysiological, and neuroimaging examinations. Therefore, impairment in energy metabolism in AD can not be attributed to loss of brain substance or to electrophysiological abnormalities. Among the characteristic abnormalities in the AD brain are deficiencies in several enzyme complexes which participate in the mitochondrial oxidation of substrates to yield energy. There include the pyruvate dehydrogenase complex (PDHC), the alpha-ketoglutarate dehydrogenase complex (KGDHC), and Complex IV of the electron transport chain (COX). The deficiency of KGDHC may be due to a mixture of causes including damage by free radicals and perhaps to genetic variation in the DLST gene encoding the core protein of this complex. Inherent impairment of glucose oxidation by the AD brain may reasonably be expected to interact synergistically with an impaired supply of oxygen and glucose to the AD brain, in causing brain damage. These considerations lead to the hypothesis that cerebrovascular compromise and inherent abnormalities in the brain's ability to oxidize substrates can interact to favor the development of AD, in individuals who are genetically predisposed to develop neuritic plaques.
Collapse
Affiliation(s)
- J P Blass
- Dementia Research Service, Burke Medical Research Institute, Weill Medical College of Cornell University, White Plains, New York 10605, USA.
| | | | | |
Collapse
|
38
|
Gibson GE, Park LC, Zhang H, Sorbi S, Calingasan NY. Oxidative stress and a key metabolic enzyme in Alzheimer brains, cultured cells, and an animal model of chronic oxidative deficits. Ann N Y Acad Sci 2000; 893:79-94. [PMID: 10672231 DOI: 10.1111/j.1749-6632.1999.tb07819.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidative stress and diminished metabolism occur in several neurodegenerative disorders. Brains from Alzheimer's disease (AD) patients exhibit several indicators of oxidative stress and have reduced activities of the alpha-ketoglutarate dehydrogenase complex (KGDHC), a key mitochondrial enzyme. Whether these abnormalities are secondary to neurodegenerative processes or are inherent properties of the cells cannot be determined in autopsy brain. Studies in cultured fibroblasts suggest that AD-related differences in oxidative stress and KGDHC reflect inherent properties of AD cells. KGDHC is sensitive to oxidative stress whether the enzyme is studied in cells, in purified mitochondria, or as an isolated protein. Reductions of brain KGDHC in living rodents lead to oxidative stress and selective cell death. The results suggest that KGDHC participates in a deleterious cascade of events related to oxidative stress that are critical in selective neuronal loss in neurodegenerative diseases.
Collapse
Affiliation(s)
- G E Gibson
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University at Burke Medical Research Institute, White Plains, New York 10605, USA.
| | | | | | | | | |
Collapse
|
39
|
Abstract
The alpha-ketoglutarate dehydrogenase complex (KGDHC) is an important mitochondrial constituent, and deficiency of KGDHC is associated with a number of neurological disorders. KGDHC is composed of three proteins, each encoded on a different and well-characterized gene. The sequences of the human proteins are known. The organization of the proteins into a large, ordered multienzyme complex (a "metabolon") has been well studied in prokaryotic and eukaryotic species. KGDHC catalyzes a critical step in the Krebs tricarboxylic acid cycle, which is also a step in the metabolism of the potentially excitotoxic neurotransmitter glutamate. A number of metabolites modify the activity of KGDHC, including inactivation by 4-hydroxynonenal and other reactive oxygen species (ROS). In human brain, the activity of KGDHC is lower than that of any other enzyme of energy metabolism, including phosphofructokinase, aconitase, and the electron transport complexes. Deficiencies of KGDHC are likely to impair brain energy metabolism and therefore brain function, and lead to manifestations of brain disease. In general, the clinical manifestations of KGDHC deficiency relate to the severity of the deficiency. Several such disorders have been recognized: infantile lactic acidosis, psychomotor retardation in childhood, intermittent neuropsychiatric disease with ataxia and other motor manifestations, Friedreich's and other spinocerebellar ataxias, Parkinson's disease, and Alzheimer's disease (AD). A KGDHC gene has been associated with the first two and last two of these disorders. KGDHC is not uniformly distributed in human brain, and the neurons that appear selectively vulnerable in human temporal cortex in AD are enriched in KGDHC. We hypothesize that variations in KGDHC that are not deleterious during reproductive life become deleterious with aging, perhaps by predisposing this mitochondrial metabolon to oxidative damage.
Collapse
Affiliation(s)
- K F Sheu
- Dementia Research Service, Burke Medical Research Institute, Weill Medical College of Cornell University, White Plains, New York 10605, USA
| | | |
Collapse
|