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Rinaldi L, Senatore E, Iannucci R, Chiuso F, Feliciello A. Control of Mitochondrial Activity by the Ubiquitin Code in Health and Cancer. Cells 2023; 12:234. [PMID: 36672167 PMCID: PMC9856579 DOI: 10.3390/cells12020234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/27/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
Cellular homeostasis is tightly connected to the broad variety of mitochondrial functions. To stay healthy, cells need a constant supply of nutrients, energy production and antioxidants defenses, undergoing programmed death when a serious, irreversible damage occurs. The key element of a functional integration of all these processes is the correct crosstalk between cell signaling and mitochondrial activities. Once this crosstalk is interrupted, the cell is not able to communicate its needs to mitochondria, resulting in oxidative stress and development of pathological conditions. Conversely, dysfunctional mitochondria may affect cell viability, even in the presence of nutrients supply and energy production, indicating the existence of feed-back control mechanisms between mitochondria and other cellular compartments. The ubiquitin proteasome system (UPS) is a multi-step biochemical pathway that, through the conjugation of ubiquitin moieties to specific protein substrates, controls cellular proteostasis and signaling, removing damaged or aged proteins that might otherwise accumulate and affect cell viability. In response to specific needs or changed extracellular microenvironment, the UPS modulates the turnover of mitochondrial proteins, thus influencing the organelle shape, dynamics and function. Alterations of the dynamic and reciprocal regulation between mitochondria and UPS underpin genetic and proliferative disorders. This review focuses on the mitochondrial metabolism and activities supervised by UPS and examines how deregulation of this control mechanism results in proliferative disorders and cancer.
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Affiliation(s)
| | | | | | | | - Antonio Feliciello
- Department of Molecular Medicine and Medical Biotechnology, University of Naples, 80131 Naples, Italy
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2
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Age-related changes in expression of lysine48 and lysine63 ubiquitin linkages in dopamine neurons of midbrain in mice. Neuroreport 2021; 32:569-576. [PMID: 33657079 DOI: 10.1097/wnr.0000000000001626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ubiquitination of target proteins is mediated via different ubiquitin lysine (K) linkages and determines the protein fates. In particular, K48 ubiquitin linkage targets proteins for degradation, whereas K63 ubiquitin linkage plays a nondegradative role. Parkinson's disease is an age-onset neurodegenerative disorder, which shows selective loss of dopamine neurons in substantia nigra pars compacta (SNC) and ubiquitinated protein aggregates. However, age-related expression of K48 and K63 ubiquitin linkages in SNC dopamine neurons remains elusive. We thus sought to explore the expression of K48 and K63 ubiquitin linkages in dopamine neurons in SNCs of mice at different ages with morphological and biochemical assays. Here our results indicated that in 5-week-old mice, dopamine neurons presented higher levels of K48 and K63 ubiquitin linkages than nondopamine neural cells. Aging promoted the formation of protein aggregates that are positive for both K48 and K63 ubiquitin linkages, together with tyrosine hydroxylase, a dopamine neuron marker. Moreover, 21-month-old mice showed fewer neural cells and tyrosine hydroxylase positive neurons in the SNCs than younger mice. Through biochemical analysis, the 21-month-old mice were shown to express more K48 ubiquitin linkages and less tyrosine hydroxylase and NeuN than the 5-week-old mice. These results suggest the first time that expression of K48 and K63 ubiquitin lysine linkages in midbrain dopamine neurons is age-related and may be involved in the loss of dopamine neurons.
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Hepowit NL, Pereira KN, Tumolo JM, Chazin WJ, MacGurn JA. Identification of ubiquitin Ser57 kinases regulating the oxidative stress response in yeast. eLife 2020; 9:58155. [PMID: 33074099 PMCID: PMC7647399 DOI: 10.7554/elife.58155] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 10/18/2020] [Indexed: 01/26/2023] Open
Abstract
Ubiquitination regulates many different cellular processes, including protein quality control, membrane trafficking, and stress responses. The diversity of ubiquitin functions in the cell is partly due to its ability to form chains with distinct linkages that can alter the fate of substrate proteins in unique ways. The complexity of the ubiquitin code is further enhanced by post-translational modifications on ubiquitin itself, the biological functions of which are not well understood. Here, we present genetic and biochemical evidence that serine 57 (Ser57) phosphorylation of ubiquitin functions in stress responses in Saccharomyces cerevisiae, including the oxidative stress response. We also identify and characterize the first known Ser57 ubiquitin kinases in yeast and human cells, and we report that two Ser57 ubiquitin kinases regulate the oxidative stress response in yeast. These studies implicate ubiquitin phosphorylation at the Ser57 position as an important modifier of ubiquitin function, particularly in response to proteotoxic stress.
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Affiliation(s)
- Nathaniel L Hepowit
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Kevin N Pereira
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Jessica M Tumolo
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Walter J Chazin
- Department of Biochemistry, Vanderbilt University, Nashville, United States
| | - Jason A MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
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4
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The ubiquitin-proteasome system and its crosstalk with mitochondria as therapeutic targets in medicine. Pharmacol Res 2020; 163:105248. [PMID: 33065283 DOI: 10.1016/j.phrs.2020.105248] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022]
Abstract
The ubiquitin-proteasome system constitutes a major pathway for protein degradation in the cell. Therefore the crosstalk of this pathway with mitochondria is a major topic with direct relevance to many mitochondrial diseases. Proteasome dysfunction triggers not only protein toxicity, but also mitochondrial dysfunction. The involvement of proteasomes in the regulation of protein transport into mitochondria contributes to an increase in mitochondrial function defects. On the other hand, mitochondrial impairment stimulates reactive oxygen species production, which increases protein damage, and protein misfolding and aggregation leading to proteasome overload. Concurrently, mitochondrial dysfunction compromises cellular ATP production leading to reduced protein ubiquitination and proteasome activity. In this review we discuss the complex relationship and interdependence of the ubiquitin-proteasome system and mitochondria. Furthermore, we describe pharmacological inhibition of proteasome activity as a novel strategy to treat a group of mitochondrial diseases.
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Colberg L, Cammann C, Greinacher A, Seifert U. Structure and function of the ubiquitin-proteasome system in platelets. J Thromb Haemost 2020; 18:771-780. [PMID: 31898400 DOI: 10.1111/jth.14730] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/30/2019] [Indexed: 12/16/2022]
Abstract
Platelets are small anucleate blood cells with a life span of 7 to 10 days. They are main regulators of hemostasis. Balanced platelet activity is crucial to prevent bleeding or occlusive thrombus formation. Growing evidence supports that platelets also participate in immune reactions, and interaction between platelets and leukocytes contributes to both thrombosis and inflammation. The ubiquitin-proteasome system (UPS) plays a key role in maintaining cellular protein homeostasis by its ability to degrade non-functional self-, foreign, or short-lived regulatory proteins. Platelets express standard and immunoproteasomes. Inhibition of the proteasome impairs platelet production and platelet function. Platelets also express major histocompatibility complex (MHC) class I molecules. Peptide fragments released by proteasomes can bind to MHC class I, which makes it also likely that platelets can activate epitope specific cytotoxic T lymphocytes (CTLs). In this review, we focus on current knowledge on the significance of the proteasome for the functions of platelets as critical regulators of hemostasis as well as modulators of the immune response.
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Affiliation(s)
- Lisa Colberg
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Clemens Cammann
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Ulrike Seifert
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
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6
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The amazing ubiquitin-proteasome system: structural components and implication in aging. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 314:171-237. [PMID: 25619718 DOI: 10.1016/bs.ircmb.2014.09.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteome quality control (PQC) is critical for the maintenance of cellular functionality and it is assured by the curating activity of the proteostasis network (PN). PN is constituted of several complex protein machines that under conditions of proteome instability aim to, firstly identify, and then, either rescue or degrade nonnative polypeptides. Central to the PN functionality is the ubiquitin-proteasome system (UPS) which is composed from the ubiquitin-conjugating enzymes and the proteasome; the latter is a sophisticated multi-subunit molecular machine that functions in a bimodal way as it degrades both short-lived ubiquitinated normal proteins and nonfunctional polypeptides. UPS is also involved in PQC of the nucleus, the endoplasmic reticulum and the mitochondria and it also interacts with the other main cellular degradation axis, namely the autophagy-lysosome system. UPS functionality is optimum in the young organism but it is gradually compromised during aging resulting in increasing proteotoxic stress; these effects correlate not only with aging but also with most age-related diseases. Herein, we present a synopsis of the UPS components and of their functional alterations during cellular senescence or in vivo aging. We propose that mild UPS activation in the young organism will, likely, promote antiaging effects and/or suppress age-related diseases.
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Mitochondrial impairment triggers cytosolic oxidative stress and cell death following proteasome inhibition. Sci Rep 2014; 4:5896. [PMID: 25077633 PMCID: PMC4116626 DOI: 10.1038/srep05896] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/14/2014] [Indexed: 01/13/2023] Open
Abstract
Dysfunctions of the mitochondria and the ubiquitin–proteasome system, as well as generation of reactive oxygen species (ROS), are linked to many aging-related neurodegenerative disorders. However, the order of these events remains unclear. Here, we show that the initial impairment occurs in mitochondria under proteasome inhibition. Fluorescent redox probe measurements revealed that proteasome inhibition led to mitochondrial oxidation followed by cytosolic oxidation, which could be prevented by a mitochondrial-targeted antioxidant or antioxidative enzyme. These observations demonstrated that proteasome dysfunction causes damage to mitochondria, leading them to increase their ROS production and resulting in cytosolic oxidation. Moreover, several antioxidants found in foods prevented intracellular oxidation and improved cell survival by maintaining mitochondrial membrane potential and reducing mitochondrial ROS generation. However, these antioxidant treatments did not decrease the accumulation of protein aggregates caused by inhibition of the proteasome. These results suggested that antioxidative protection of mitochondria maintains cellular integrity, providing novel insights into the mechanisms of cell death caused by proteasome dysfunction.
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Higgins GC, Coughlan MT. Mitochondrial dysfunction and mitophagy: the beginning and end to diabetic nephropathy? Br J Pharmacol 2014; 171:1917-42. [PMID: 24720258 PMCID: PMC3976613 DOI: 10.1111/bph.12503] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 10/15/2013] [Accepted: 10/24/2013] [Indexed: 12/14/2022] Open
Abstract
Diabetic nephropathy (DN) is a progressive microvascular complication arising from diabetes. Within the kidney, the glomeruli, tubules, vessels and interstitium are disrupted, ultimately impairing renal function and leading to end-stage renal disease (ESRD). Current pharmacological therapies used in individuals with DN do not prevent the inevitable progression to ESRD; therefore, new targets of therapy are urgently required. Studies from animal models indicate that disturbances in mitochondrial homeostasis are central to the pathogenesis of DN. Since renal proximal tubule cells rely on oxidative phosphorylation to provide adequate ATP for tubular reabsorption, an impairment of mitochondrial bioenergetics can result in renal functional decline. Defects at the level of the electron transport chain have long been established in DN, promoting electron leakage and formation of superoxide radicals, mediating microinflammation and contributing to the renal lesion. More recent studies suggest that mitochondrial-associated proteins may be directly involved in the pathogenesis of tubulointerstitial fibrosis and glomerulosclerosis. An accumulation of fragmented mitochondria are found in the renal cortex in both humans and animals with DN, suggesting that in tandem with a shift in dynamics, mitochondrial clearance mechanisms may be impaired. The process of mitophagy is the selective targeting of damaged or dysfunctional mitochondria to autophagosomes for degradation through the autophagy pathway. The current review explores the concept that an impairment in the mitophagy system leads to the accelerated progression of renal pathology. A better understanding of the cellular and molecular events that govern mitophagy and dynamics in DN may lead to improved therapeutic strategies.
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Affiliation(s)
- G C Higgins
- Glycation, Nutrition & Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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Differential ubiquitination and degradation of huntingtin fragments modulated by ubiquitin-protein ligase E3A. Proc Natl Acad Sci U S A 2014; 111:5706-11. [PMID: 24706802 DOI: 10.1073/pnas.1402215111] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Ubiquitination of misfolded proteins, a common feature of many neurodegenerative diseases, is mediated by different lysine (K) residues in ubiquitin and alters the levels of toxic proteins. In Huntington disease, polyglutamine expansion causes N-terminal huntingtin (Htt) to misfold, inducing neurodegeneration. Here we report that shorter N-terminal Htt fragments are more stable than longer fragments and find differential ubiquitination via K63 of ubiquitin. Aging decreases proteasome-mediated Htt degradation, at the same time increasing K63-mediated ubiquitination and subsequent Htt aggregation in HD knock-in mice. The association of Htt with the K48-specific E3 ligase, Ube3a, is decreased in aged mouse brain. Overexpression of Ube3a in HD mouse brain reduces K63-mediated ubiquitination and Htt aggregation, enhancing its degradation via the K48 ubiquitin-proteasome system. Our findings suggest that aging-dependent Ube3a levels result in differential ubiquitination and degradation of Htt fragments, thereby contributing to the age-related neurotoxicity of mutant Htt.
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Lim KH, Ramakrishna S, Baek KH. Molecular mechanisms and functions of cytokine-inducible deubiquitinating enzymes. Cytokine Growth Factor Rev 2013; 24:427-31. [PMID: 23773437 DOI: 10.1016/j.cytogfr.2013.05.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 05/13/2013] [Accepted: 05/21/2013] [Indexed: 12/20/2022]
Abstract
Deubiquitinating enzymes (DUBs), a class of cysteine proteases which counteract the action of protein ubiquitination, hydrolyze ubiquitin from its specific targeted proteins. Approximately, 100 DUBs have been found from yeast to human, and they can be classified into at least 5 families based on their structures and functions. Most DUBs are involved in regulation of intracellular processes including cell cycle progression, apoptosis, immunity, reproduction, and target gene transcription. Recently, much progress has been made in understanding the physiological functions of cytokine-inducible DUBs such as DUB-1, DUB-2, and DUB-3/USP17, in regulation of cell proliferation and apoptosis in lymphocytes. Here, we have summarized the structure and functions of cytokine-inducible DUBs and their biological functions in regulating several interleukin-associated signaling pathways. Finally, we emphasize the importance of small molecules for cytokine-inducible DUBs for developing promising drug therapeutics for immune-related disorders.
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Affiliation(s)
- Key-Hwan Lim
- Department of Biomedical Science, CHA University, Bundang CHA General Hospital, Gyeonggi-Do 463-840, Republic of Korea
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11
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Martins-Branco D, Esteves AR, Santos D, Arduino DM, Swerdlow RH, Oliveira CR, Januario C, Cardoso SM. Ubiquitin proteasome system in Parkinson's disease: a keeper or a witness? Exp Neurol 2012; 238:89-99. [PMID: 22921536 DOI: 10.1016/j.expneurol.2012.08.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 07/26/2012] [Accepted: 08/07/2012] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The aim of this work was to evaluate the role of ubiquitin-proteasome system (UPS) on mitochondrial-driven alpha-synuclein (aSN) clearance in in vitro, ex vivo and in vivo Parkinson's disease (PD) cellular models. METHOD We used SH-SY5Y ndufa2 knock-down (KD) cells, PD cybrids and peripheral blood mononuclear cells (PBMC) from patients meeting the diagnostic criteria for PD. We quantified aSN aggregation, proteasome activity and protein ubiquitination levels. In PBMC of PD patient population we evaluated the aSN levels in the plasma and the influence of several demographic characteristics in the above mentioned determinations. RESULTS We found that ubiquitin-independent proteasome activity was up-regulated in SH-SY5Y ndufa2 KD cells while a downregulation was observed in PD cybrids and PBMC. Moreover, we observed an increase in protein ubiquitination that correlates with a decrease in ubiquitin-dependent proteasome activity. Accordingly, proteasome inhibition prevented ubiquitin-dependent aSN clearance. Ubiquitin-independent proteasome activity was positively correlated with ubiquitination in PBMC. We also report a negative correlation of chymotrypsin-like activity with age in control and late-onset PD groups. Total ubiquitin content is positively correlated with aSN oligomer levels, which leads to an age-dependent increase of aSN ubiquitination in LOPD. Moreover, aSN levels are increased in the plasma of PD patients. INTERPRETATION aSN oligomers are ubiquitinated and we identified a ubiquitin-dependent clearance insufficiency with the accumulation of both aSN and ubiquitin. However, SH-SY5Y ndufa2 KD cells showed a significant up-regulation of ubiquitin-independent proteasomal enzymatic activity that could mean a cell rescue attempt. Moreover, we identified that UPS function is age-dependent in PBMC.
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Lin M, Chandramani-Shivalingappa P, Jin H, Ghosh A, Anantharam V, Ali S, Kanthasamy AG, Kanthasamy A. Methamphetamine-induced neurotoxicity linked to ubiquitin-proteasome system dysfunction and autophagy-related changes that can be modulated by protein kinase C delta in dopaminergic neuronal cells. Neuroscience 2012; 210:308-32. [PMID: 22445524 DOI: 10.1016/j.neuroscience.2012.03.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 02/09/2012] [Accepted: 03/04/2012] [Indexed: 01/07/2023]
Abstract
A compromised protein degradation machinery has been implicated in methamphetamine (MA)-induced neurodegeneration. However, the signaling mechanisms that induce autophagy and ubiquitin-proteasome system (UPS) dysfunction are not well understood. The present study investigates the contributions of protein kinase C delta (PKCδ)-mediated signaling events in MA-induced autophagy, UPS dysfunction, and cell death. Using an in vitro mesencephalic dopaminergic cell culture model, we demonstrate that MA-induced early induction of autophagy is associated with reduction in proteasomal function and concomitant dissipation of mitochondrial membrane potential (MMP), followed by significantly increased PKCδ activation, caspase-3 activation, accumulation of ubiquitin-positive aggregates and microtubule-associated light chain-3 (LC3-II) levels. Interestingly, siRNA-mediated knockdown of PKCδ or overexpression of cleavage-resistant mutant of PKCδ dramatically reduced MA-induced autophagy, proteasomal function, and associated accumulation of ubiquitinated protein aggregates, which closely paralleled cell survival. Importantly, when autophagy was inhibited either pharmacologically (3-MA) or genetically (siRNA-mediated silencing of LC3), the dopaminergic cells became sensitized to MA-induced apoptosis through caspase-3 activation. Conversely, overexpression of LC3 partially protected against MA-induced apoptotic cell death, suggesting a neuroprotective role for autophagy in MA-induced neurotoxicity. Notably, rat striatal tissue isolated from MA-treated rats also exhibited elevated LC3-II, ubiquitinated protein levels, and PKCδ cleavage. Taken together, our data demonstrate that MA-induced autophagy serves as an adaptive strategy for inhibiting mitochondria-mediated apoptotic cell death and degradation of aggregated proteins. Our results also suggest that the sustained activation of PKCδ leads to UPS dysfunction, resulting in the activation of caspase-3-mediated apoptotic cell death in the nigrostriatal dopaminergic system.
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Affiliation(s)
- M Lin
- Parkinson's Disorder Research Laboratory, Iowa Center for Advanced Neurotoxicology, Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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Jenner P, Langston JW. Explaining ADAGIO: a critical review of the biological basis for the clinical effects of rasagiline. Mov Disord 2011; 26:2316-23. [PMID: 21953831 DOI: 10.1002/mds.23926] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/05/2011] [Accepted: 07/11/2011] [Indexed: 12/31/2022] Open
Abstract
The ADAGIO study demonstrated a symptomatic benefit for rasagiline in early Parkinson's disease (PD) and suggested a disease-modifying effect. Evidence indicates that mitochondrial dysfunction plays a role in the pathogenesis of PD and that this may be the site of effect for rasagiline. In this systematic review, evidence for the role of mitochondria in the pathogenesis of PD are reviewed in light of other proposed mechanisms of neuronal degeneration and the actions of rasagiline and its component parts, namely propargylamine and the metabolite, aminoindan. Evidence for the role of mitochondria in the pathogenesis and treatment of PD are reviewed in light of other proposed mechanisms of neuronal degeneration and clinical actions of rasagiline. Monoamine oxidase B (MAO-B) located in the outer mitochondrial membrane controls dopamine metabolism in early PD, and this is the likely location for the symptomatic action of rasagiline. Accumulating evidence indicates that mitochondrial impairment contributes to dopaminergic neuronal loss in PD, either directly or through other mechanisms such as oxidative stress or protein misfolding. Further rasagiline affects numerous mitochondrial mechanisms that prevent apoptotic cell death including prevention of opening of the mitochondrial transition pore, decreased release of cytochrome C, alterations in pro-antiapoptotic genes and proteins, and the nuclear translocation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Thus, the functional neuroprotective actions of rasagiline may not be dependent on MAO-B inhibition, but rather may involve actions of the propargylamine moiety and the aminoindan metabolite. An accumulating body of literature indicates a mitochondrial site of action for rasagiline and highlights the neuroprotective action of the drug, providing strong biological plausibility for disease-modifying effects of the drug such as those observed in ADAGIO.
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Affiliation(s)
- Peter Jenner
- Neurodegenerative Diseases Research Centre, School of Health and Biomedical Sciences, King's College, London, UK.
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Kim MS, Ramakrishna S, Lim KH, Kim JH, Baek KH. Protein stability of mitochondrial superoxide dismutase SOD2 is regulated by USP36. J Cell Biochem 2011; 112:498-508. [PMID: 21268071 DOI: 10.1002/jcb.22940] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
SOD2 is a key mitochondrial antioxidant enzyme and its perturbation leads to oxidative cell death, which results in various disorders. In this study, we identified a deubiquitinating enzyme USP36 that regulates the protein stability of SOD2. The regulatory effect of USP36 on SOD2 was initially identified by 2-DE and MALDI-TOF/MS analyses. In addition, endogenous USP36 and SOD2 were shown to interact in an immunoprecipitation assay, which was verified using the yeast two-hybrid system. Furthermore, we demonstrated that SOD2 binds with ubiquitin molecules to form polyubiquitination chains and undergoes degradation through the ubiquitin-proteasomal pathway. Finally, USP36 was shown to be a specific deubiquitinating enzyme that reduces the ubiquitination level of SOD2 and was involved in SOD2 protein stability by extending its half-life.
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Affiliation(s)
- Myung-Sun Kim
- Department of Biomedical Science, CHA General Hospital, CHA University, Seoul, Republic of Korea
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15
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Sun F, Kanthasamy AG, Kanthasamy A. Measurement of proteasomal dysfunction in cell models of dopaminergic degeneration. Methods Mol Biol 2011; 758:293-305. [PMID: 21815074 DOI: 10.1007/978-1-61779-170-3_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative diseases, which occurs in both inheritable and sporadic forms. The interplay of the genetic mutations and environmental exposure to disease risk factors contributes to the pathogenic events leading to the demise of dopaminergic neurons in PD. Proteasome is one of the major proteolytic machinery responsible for degrading unwanted and damaged intracellular proteins. Emerging evidence implicates the incomplete proteolysis by ubiquitin-proteasome system (UPS) in PD pathogenesis. Proteasome inhibition recapitulates some of the key features of PD in vivo and in vitro. Varieties of dopaminergic neurotoxins emerge to inhibit proteasomal function. Given that some PD-related gene mutations impair proteolytic function of UPS, it has been well-accepted that both genetic and environmental factors may conspire to compromise the UPS in the initiation and progression of the disease. The enzymatic assays for the proteasomal activities with fluorogenic substrates and western blot analysis of ubiquitinated proteins provide an entry point to determine UPS function in the process of dopaminergic degeneration.
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Affiliation(s)
- Faneng Sun
- Parkinson's Disorder Research Laboratory, Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA, USA
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16
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K63-linked ubiquitination and neurodegeneration. Neurobiol Dis 2010; 43:9-16. [PMID: 20696248 DOI: 10.1016/j.nbd.2010.08.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 07/28/2010] [Accepted: 08/01/2010] [Indexed: 11/23/2022] Open
Abstract
The proteasome, which identifies and destroys unwanted proteins rapidly, plays a vital role in maintaining cellular protein homeostasis. Proteins that are destined for proteasome-mediated degradation are usually tagged with a chain of ubiquitin linked via lysine (K) 48 that targets them to the proteolytic machinery. However, when the proteasome becomes compromised in its function, it is attractive to think that the cell may switch to an alternative, non-proteolytic form of ubiquitination that could help divert cargo proteins away from an otherwise overloaded proteasome. Of the several types of ubiquitin chain topologies, K63-linked ubiquitination is the only one known to fulfil diverse proteasome-independent roles, including DNA repair, endocytosis and NFκB signaling. By virtue of its apparent dissociation from the proteasome, we have originally proposed that K63-linked ubiquitination may be involved in cargo diversion during proteasomal stress and accordingly, in the biogenesis of inclusion bodies associated with neurodegenerative diseases. Here, we provide an overview of this non-classic form of ubiquitin modification, and discuss current evidence and controversies surrounding our proposed role for K63 polyubiquitin as a key regulator of inclusion dynamics that is relevant to neurodegeneration. This article is part of a Special Issue entitled "Autophagy and protein degradation in neurological diseases."
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Branco DM, Arduino DM, Esteves AR, Silva DFF, Cardoso SM, Oliveira CR. Cross-talk between mitochondria and proteasome in Parkinson's disease pathogenesis. Front Aging Neurosci 2010; 2:17. [PMID: 20577640 PMCID: PMC2890153 DOI: 10.3389/fnagi.2010.00017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 04/12/2010] [Indexed: 11/17/2022] Open
Abstract
Parkinson's disease (PD) is the most common progressive neurodegenerative movement disorder, characterized by the selective loss of nigrostriatal dopaminergic neurons, and the presence of intracellular insoluble proteinaceous inclusions, known as Lewy Bodies. Although PD etiopathogenesis remains elusive, the leading hypothesis for the death of specific groups of neurons establishes that mitochondrial dysfunction, alterations in the ubiquitin-proteasomal system (UPS), and oxidative stress are major events that act synergistically causing this devastating disease. In this review we will focus on mitochondrial impairment and its implications on proteasomal function and alpha-synuclein aggregation. We will address the role of mitochondria and proteasome cross-talk in the neuronal loss that leads to PD and discuss how this knowledge might further improve patient therapy.
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Affiliation(s)
- Diogo Martins Branco
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
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Hipkiss AR. Aging, Proteotoxicity, Mitochondria, Glycation, NAD and Carnosine: Possible Inter-Relationships and Resolution of the Oxygen Paradox. Front Aging Neurosci 2010; 2:10. [PMID: 20552048 PMCID: PMC2874395 DOI: 10.3389/fnagi.2010.00010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 03/01/2010] [Indexed: 11/13/2022] Open
Abstract
It is suggested that NAD(+) availability strongly affects cellular aging and organism lifespan: low NAD(+) availability increases intracellular levels of glycolytic triose phosphates (glyceraldehyde-3-phosphate and dihydroxyacetone-phosphate) which, if not further metabolized, decompose spontaneously into methylglyoxal (MG), a glycating agent and source of protein and mitochondrial dysfunction and reactive oxygen species (ROS). MG-damaged proteins and other aberrant polypeptides can induce ROS generation, promote mitochondrial dysfunction and inhibit proteasomal activity. Upregulation of mitogenesis and mitochondrial activity by increased aerobic exercise, or dietary manipulation, helps to maintain NAD(+)availability and thereby decreases MG-induced proteotoxicity. These proposals can explain the apparent paradox whereby aging is seemingly caused by increased ROS-mediated macromolecular damage but is ameliorated by increased aerobic activity. It is also suggested that increasing mitochondrial activity decreases ROS generation, while excess numbers of inactive mitochondria are deleterious due to increased ROS generation. The muscle- and brain-associated dipeptide, carnosine, is an intracellular buffer which can delay senescence in cultured human fibroblasts and delay aging in senescence-accelerated mice. Carnosine's ability to react with MG and possibly other deleterious carbonyl compounds, and scavenge various ROS, may account for its protective ability towards ischemia and ageing.
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Affiliation(s)
- Alan R Hipkiss
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, The University of Birmingham Birmingham, UK
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Song C, Kanthasamy A, Anantharam V, Sun F, Kanthasamy AG. Environmental neurotoxic pesticide increases histone acetylation to promote apoptosis in dopaminergic neuronal cells: relevance to epigenetic mechanisms of neurodegeneration. Mol Pharmacol 2010; 77:621-32. [PMID: 20097775 DOI: 10.1124/mol.109.062174] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pesticide exposure has been implicated in the etiopathogenesis of Parkinson's disease (PD); in particular, the organochlorine insecticide dieldrin is believed to be associated with PD. Emerging evidence indicates that histone modifications play a critical role in cell death. In this study, we examined the effects of dieldrin treatment on histone acetylation and its role in dieldrin-induced apoptotic cell death in dopaminergic neuronal cells. In mesencephalic dopaminergic neuronal cells, dieldrin induced a time-dependent increase in the acetylation of core histones H3 and H4. Histone acetylation occurred within 10 min of dieldrin exposure indicating that acetylation is an early event in dieldrin neurotoxicity. The hyperacetylation was attributed to dieldrin-induced proteasomal dysfunction, resulting in accumulation of a key histone acetyltransferase (HAT), cAMP response element-binding protein. The novel HAT inhibitor anacardic acid significantly attenuated dieldrin-induced histone acetylation, Protein kinase C delta proteolytic activation and DNA fragmentation in dopaminergic cells protected against dopaminergic neuronal degeneration in primary mesencephalic neuronal cultures. Furthermore, 30-day exposure of dieldrin in mouse models induced histone hyperacetylation in the striatum and substantia nigra. For the first time, our results collectively demonstrate that exposure to the neurotoxic pesticide dieldrin induces acetylation of core histones because of proteasomal dysfunction and that hyperacetylation plays a key role in dopaminergic neuronal degeneration after exposure of dieldrin.
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Affiliation(s)
- C Song
- Iowa Center for Advanced Neurotoxicology, Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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Afeseh Ngwa H, Kanthasamy A, Anantharam V, Song C, Witte T, Houk R, Kanthasamy AG. Vanadium induces dopaminergic neurotoxicity via protein kinase Cdelta dependent oxidative signaling mechanisms: relevance to etiopathogenesis of Parkinson's disease. Toxicol Appl Pharmacol 2009; 240:273-85. [PMID: 19646462 DOI: 10.1016/j.taap.2009.07.025] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 07/17/2009] [Accepted: 07/20/2009] [Indexed: 01/03/2023]
Abstract
Environmental exposure to neurotoxic metals through various sources including exposure to welding fumes has been linked to an increased incidence of Parkinson's disease (PD). Welding fumes contain many different metals including vanadium typically present as particulates containing vanadium pentoxide (V2O5). However, possible neurotoxic effects of this metal oxide on dopaminergic neuronal cells are not well studied. In the present study, we characterized vanadium-induced oxidative stress-dependent cellular events in cell culture models of PD. V2O5 was neurotoxic to dopaminergic neuronal cells including primary nigral dopaminergic neurons and the EC50 was determined to be 37 microM in N27 dopaminergic neuronal cell model. The neurotoxic effect was accompanied by a time-dependent uptake of vanadium and upregulation of metal transporter proteins Tf and DMT1 in N27 cells. Additionally, vanadium resulted in a threefold increase in reactive oxygen species generation, followed by release of mitochondrial cytochrome c into cytoplasm and subsequent activation of caspase-9 (>fourfold) and caspase-3 (>ninefold). Interestingly, vanadium exposure induced proteolytic cleavage of native protein kinase Cdelta (PKCdelta, 72-74 kDa) to yield a 41 kDa catalytically active fragment resulting in a persistent increase in PKCdelta kinase activity. Co-treatment with pan-caspase inhibitor Z-VAD-FMK significantly blocked vanadium-induced PKCdelta proteolytic activation, indicating that caspases mediate PKCdelta cleavage. Also, co-treatment with Z-VAD-FMK almost completely inhibited V2O5-induced DNA fragmentation. Furthermore, PKCdelta knockdown using siRNA protected N27 cells from V2O5-induced apoptotic cell death. Collectively, these results demonstrate that vanadium can exert neurotoxic effects in dopaminergic neuronal cells via caspase-3-dependent PKCdelta cleavage, suggesting that metal exposure may promote nigral dopaminergic degeneration.
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Affiliation(s)
- Hilary Afeseh Ngwa
- Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, IA 50011, USA
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