1
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Mao S. Emerging role and the signaling pathways of uncoupling protein 2 in kidney diseases. Ren Fail 2024; 46:2381604. [PMID: 39090967 PMCID: PMC11299446 DOI: 10.1080/0886022x.2024.2381604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 06/18/2024] [Accepted: 07/13/2024] [Indexed: 08/04/2024] Open
Abstract
OBJECTIVES Uncoupling protein 2 (UCP2) was involved in the pathogenesis and development of kidney diseases. Many signaling pathways and factors regulate the expression of UCP2. We aimed to investigate the precise role of UCP2 and its signaling pathways in kidney diseases. METHODS We summarized the available evidence to yield a more detailed conclusion of the signal transduction pathways of UCP2 and its role in the development and progression of kidney diseases. RESULTS UCP2 could interact with 14.3.3 family proteins, mitochondrial phospholipase iPLA2γ, NMDAR, glucokinase, PPARγ2. There existed a signaling pathway between UCP2 and NMDAR, PPARγ. UCP2 can inhibit the ROS production, inflammatory response, and apoptosis, which may protect against renal injury, particularly AKI. Meanwhile UCP2 can decrease ATP production and inhibit the secretion of insulin, which may alleviate chronic renal damages, such as diabetic nephropathy and kidney fibrosis. CONCLUSIONS Homeostasis of UCP2 is helpful for kidney health. UCP2 may play different roles in different kinds of renal injury.
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Affiliation(s)
- Song Mao
- Department of Pediatrics, Shanghai Sixth People’s Hospital, Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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2
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Jabůrek M, Klöppel E, Průchová P, Mozheitova O, Tauber J, Engstová H, Ježek P. Mitochondria to plasma membrane redox signaling is essential for fatty acid β-oxidation-driven insulin secretion. Redox Biol 2024; 75:103283. [PMID: 39067330 PMCID: PMC11332078 DOI: 10.1016/j.redox.2024.103283] [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: 07/17/2024] [Revised: 07/22/2024] [Accepted: 07/22/2024] [Indexed: 07/30/2024] Open
Abstract
We asked whether acute redox signaling from mitochondria exists concomitantly to fatty acid- (FA-) stimulated insulin secretion (FASIS) at low glucose by pancreatic β-cells. We show that FA β-oxidation produces superoxide/H2O2, providing: i) mitochondria-to-plasma-membrane redox signaling, closing KATP-channels synergically with elevated ATP (substituting NADPH-oxidase-4-mediated H2O2-signaling upon glucose-stimulated insulin secretion); ii) activation of redox-sensitive phospholipase iPLA2γ/PNPLA8, cleaving mitochondrial FAs, enabling metabotropic GPR40 receptors to amplify insulin secretion (IS). At fasting glucose, palmitic acid stimulated IS in wt mice; palmitic, stearic, lauric, oleic, linoleic, and hexanoic acids also in perifused pancreatic islets (PIs), with suppressed 1st phases in iPLA2γ/PNPLA8-knockout mice/PIs. Extracellular/cytosolic H2O2-monitoring indicated knockout-independent redox signals, blocked by mitochondrial antioxidant SkQ1, etomoxir, CPT1 silencing, and catalase overexpression, all inhibiting FASIS, keeping ATP-sensitive K+-channels open, and diminishing cytosolic [Ca2+]-oscillations. FASIS in mice was a postprandially delayed physiological event. Redox signals of FA β-oxidation are thus documented, reaching the plasma membrane, essentially co-stimulating IS.
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Affiliation(s)
- Martin Jabůrek
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Eduardo Klöppel
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Pavla Průchová
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Oleksandra Mozheitova
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Jan Tauber
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Hana Engstová
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic
| | - Petr Ježek
- Department of Mitochondrial Physiology, No.75, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, 14220, Czech Republic.
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3
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Ježek P, Dlasková A, Engstová H, Špačková J, Tauber J, Průchová P, Kloppel E, Mozheitova O, Jabůrek M. Mitochondrial Physiology of Cellular Redox Regulations. Physiol Res 2024; 73:S217-S242. [PMID: 38647168 DOI: 10.33549/physiolres.935269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Mitochondria (mt) represent the vital hub of the molecular physiology of the cell, being decision-makers in cell life/death and information signaling, including major redox regulations and redox signaling. Now we review recent advances in understanding mitochondrial redox homeostasis, including superoxide sources and H2O2 consumers, i.e., antioxidant mechanisms, as well as exemplar situations of physiological redox signaling, including the intramitochondrial one and mt-to-cytosol redox signals, which may be classified as acute and long-term signals. This review exemplifies the acute redox signals in hypoxic cell adaptation and upon insulin secretion in pancreatic beta-cells. We also show how metabolic changes under these circumstances are linked to mitochondrial cristae narrowing at higher intensity of ATP synthesis. Also, we will discuss major redox buffers, namely the peroxiredoxin system, which may also promote redox signaling. We will point out that pathological thresholds exist, specific for each cell type, above which the superoxide sources exceed regular antioxidant capacity and the concomitant harmful processes of oxidative stress subsequently initiate etiology of numerous diseases. The redox signaling may be impaired when sunk in such excessive pro-oxidative state.
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Affiliation(s)
- P Ježek
- Laboratory of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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4
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Caggiano EG, Taniguchi CM. UCP2 and pancreatic cancer: conscious uncoupling for therapeutic effect. Cancer Metastasis Rev 2024; 43:777-794. [PMID: 38194152 PMCID: PMC11156755 DOI: 10.1007/s10555-023-10157-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/13/2023] [Indexed: 01/10/2024]
Abstract
Pancreatic cancer has an exaggerated dependence on mitochondrial metabolism, but methods to specifically target the mitochondria without off target effects in normal tissues that rely on these organelles is a significant challenge. The mitochondrial uncoupling protein 2 (UCP2) has potential as a cancer-specific drug target, and thus, we will review the known biology of UCP2 and discuss its potential role in the pathobiology and future therapy of pancreatic cancer.
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Affiliation(s)
- Emily G Caggiano
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | - Cullen M Taniguchi
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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5
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Antioxidant Role and Cardiolipin Remodeling by Redox-Activated Mitochondrial Ca 2+-Independent Phospholipase A 2γ in the Brain. Antioxidants (Basel) 2022; 11:antiox11020198. [PMID: 35204081 PMCID: PMC8868467 DOI: 10.3390/antiox11020198] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 02/01/2023] Open
Abstract
Mitochondrial Ca2+-independent phospholipase A2γ (iPLA2γ/PNPLA8) was previously shown to be directly activated by H2O2 and release free fatty acids (FAs) for FA-dependent H+ transport mediated by the adenine nucleotide translocase (ANT) or uncoupling protein 2 (UCP2). The resulting mild mitochondrial uncoupling and consequent partial attenuation of mitochondrial superoxide production lead to an antioxidant effect. However, the antioxidant role of iPLA2γ in the brain is not completely understood. Here, using wild-type and iPLA2γ-KO mice, we demonstrate the ability of tert-butylhydroperoxide (TBHP) to activate iPLA2γ in isolated brain mitochondria, with consequent liberation of FAs and lysophospholipids. The liberated FA caused an increase in respiratory rate, which was fully inhibited by carboxyatractyloside (CATR), a specific inhibitor of ANT. Employing detailed lipidomic analysis, we also demonstrate a typical cleavage pattern for TBHP-activated iPLA2γ, reflecting cleavage of glycerophospholipids from both sn-1 and sn-2 positions releasing saturated FAs, monoenoic FAs, and predominant polyunsaturated FAs. The acute antioxidant role of iPLA2γ-released FAs is supported by monitoring both intramitochondrial superoxide and extramitochondrial H2O2 release. We also show that iPLA2γ-KO mice were more sensitive to stimulation by pro-inflammatory lipopolysaccharide, as reflected by the concomitant increase in protein carbonyls in the brain and pro-inflammatory IL-6 release in the serum. These data support the antioxidant and anti-inflammatory role of iPLA2γ in vivo. Our data also reveal a substantial decrease of several high molecular weight cardiolipin (CL) species and accumulation of low molecular weight CL species in brain mitochondria of iPLA2γ-KO mice. Collectively, our results support a key role of iPLA2γ in the remodeling of lower molecular weight immature cardiolipins with predominantly saturated acyl chains to high molecular weight mature cardiolipins with highly unsaturated PUFA acyl chains, typical for the brain.
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6
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Jabůrek M, Průchová P, Holendová B, Galkin A, Ježek P. Antioxidant Synergy of Mitochondrial Phospholipase PNPLA8/iPLA2γ with Fatty Acid-Conducting SLC25 Gene Family Transporters. Antioxidants (Basel) 2021; 10:antiox10050678. [PMID: 33926059 PMCID: PMC8146845 DOI: 10.3390/antiox10050678] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/13/2021] [Accepted: 04/22/2021] [Indexed: 02/07/2023] Open
Abstract
Patatin-like phospholipase domain-containing protein PNPLA8, also termed Ca2+-independent phospholipase A2γ (iPLA2γ), is addressed to the mitochondrial matrix (or peroxisomes), where it may manifest its unique activity to cleave phospholipid side-chains from both sn-1 and sn-2 positions, consequently releasing either saturated or unsaturated fatty acids (FAs), including oxidized FAs. Moreover, iPLA2γ is directly stimulated by H2O2 and, hence, is activated by redox signaling or oxidative stress. This redox activation permits the antioxidant synergy with mitochondrial uncoupling proteins (UCPs) or other SLC25 mitochondrial carrier family members by FA-mediated protonophoretic activity, termed mild uncoupling, that leads to diminishing of mitochondrial superoxide formation. This mechanism allows for the maintenance of the steady-state redox status of the cell. Besides the antioxidant role, we review the relations of iPLA2γ to lipid peroxidation since iPLA2γ is alternatively activated by cardiolipin hydroperoxides and hypothetically by structural alterations of lipid bilayer due to lipid peroxidation. Other iPLA2γ roles include the remodeling of mitochondrial (or peroxisomal) membranes and the generation of specific lipid second messengers. Thus, for example, during FA β-oxidation in pancreatic β-cells, H2O2-activated iPLA2γ supplies the GPR40 metabotropic FA receptor to amplify FA-stimulated insulin secretion. Cytoprotective roles of iPLA2γ in the heart and brain are also discussed.
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Affiliation(s)
- Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1084, 14220 Prague, Czech Republic; (P.P.); (B.H.); (P.J.)
- Correspondence: ; Tel.: +420-296442789
| | - Pavla Průchová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1084, 14220 Prague, Czech Republic; (P.P.); (B.H.); (P.J.)
| | - Blanka Holendová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1084, 14220 Prague, Czech Republic; (P.P.); (B.H.); (P.J.)
| | - Alexander Galkin
- Department of Pediatrics, Division of Neonatology, Columbia University William Black Building, New York, NY 10032, USA;
| | - Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1084, 14220 Prague, Czech Republic; (P.P.); (B.H.); (P.J.)
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7
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Xia F, Chen H, Jin Z, Fu Z. Apelin-13 protects the lungs from ischemia-reperfusion injury by attenuating inflammatory and oxidative stress. Hum Exp Toxicol 2021; 40:685-694. [PMID: 33025833 DOI: 10.1177/0960327120961436] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Apelin has been reported to regulate mitochondrial function in myocardial ischemia-reperfusion injury and cerebral ischemia-reperfusion injury. However, the role of apelin-13 in lung ischemia-reperfusion injury (LIRI) remains unclear. This study established an experimental rat model to evaluate the underlying mechanisms of apelin-13 on LIRI. Twenty-four rats were randomly divided to sham operation group (group SM), ischemia/reperfusion group (group IR), and apelin-13 treatment group (group APL). The effects of apelin-13 on LIRI were determined histologically using H&E staining, while the wet/dry weight ratio was used to assess lung edema caused by LIRI. Inflammatory cytokines were also detected in Bronchoalveolar lavage (BAL) fluid by ELISA. The protein expression of UCP2 and the morphological changes of mitochondria were determined by western blotting and electromicroscopy, respectively. The results demonstrated the structural damage of lung tissues and lung edema in group IR. An increased level of inflammatory cytokines including IL-1β, IL-6 and TNF-α was observed in rats with LIRI using ELISA. After that, oxidative stress and morphological damage of mitochondria were also shown in group IR. Yet, the application of apelin-13 reversed all these deleterious effects in group APL. The protective effects of apelin-13 were indicated by decreased reactive oxygen species (ROS) and elevated UCP2 expression levels in rats. In conclusion, this study revealed that apelin-13 had protective effects against LIRI via attenuating lung edema, the production of inflammatory cytokines, oxidative stress and mitochondrial dysfunction.
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Affiliation(s)
- F Xia
- Department of Pain Management, Shandong Provincial Hospital, Cheeloo College of Medicine, 12589Shandong University, Jinan, Shandong Province, China
- Department of Anesthesiology, 89657The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China
| | - H Chen
- Department of Anesthesiology, 89657The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China
| | - Z Jin
- Department of Anesthesiology, 89657The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China
| | - Z Fu
- Department of Pain Management, Shandong Provincial Hospital, Cheeloo College of Medicine, 12589Shandong University, Jinan, Shandong Province, China
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8
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Scholtes C, Giguère V. Transcriptional Regulation of ROS Homeostasis by the ERR Subfamily of Nuclear Receptors. Antioxidants (Basel) 2021; 10:antiox10030437. [PMID: 33809291 PMCID: PMC7999130 DOI: 10.3390/antiox10030437] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 01/08/2023] Open
Abstract
Reactive oxygen species (ROS) such as superoxide anion (O2•-) and hydrogen peroxide (H2O2) are generated endogenously by processes such as mitochondrial oxidative phosphorylation, or they may arise from exogenous sources like bacterial invasion. ROS can be beneficial (oxidative eustress) as signaling molecules but also harmful (oxidative distress) to cells when ROS levels become unregulated in response to physiological, pathological or pharmacological insults. Indeed, abnormal ROS levels have been shown to contribute to the etiology of a wide variety of diseases. Transcriptional control of metabolic genes is a crucial mechanism to coordinate ROS homeostasis. Therefore, a better understanding of how ROS metabolism is regulated by specific transcription factors can contribute to uncovering new therapeutic strategies. A large body of work has positioned the estrogen-related receptors (ERRs), transcription factors belonging to the nuclear receptor superfamily, as not only master regulators of cellular energy metabolism but, most recently, of ROS metabolism. Herein, we will review the role played by the ERRs as transcriptional regulators of ROS generation and antioxidant mechanisms and also as ROS sensors. We will assess how the control of ROS homeostasis by the ERRs can be linked to physiology and disease and the possible contribution of manipulating ERR activity in redox medicine.
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Affiliation(s)
- Charlotte Scholtes
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montréal, QC H3A 1A3, Canada;
| | - Vincent Giguère
- Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montréal, QC H3A 1A3, Canada;
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada
- Correspondence:
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9
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Chen YF, Feng DD, Wu SH, Lu HY, Banu Pasha A, Permall DL, Chen JH, Sun ZY, Li BJ, Zhou H, Yang Y, Zhang XJ, Chen XQ. Promotion of Bronchopulmonary Dysplasia Progression Using Circular RNA circabcc4 via Facilitating PLA2G6 Expression by Sequestering miR-663a. Front Cell Dev Biol 2020; 8:585541. [PMID: 33195232 PMCID: PMC7654334 DOI: 10.3389/fcell.2020.585541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/08/2020] [Indexed: 12/04/2022] Open
Abstract
Circular RNA (circRNA) has been increasingly proven as a new type of promising therapeutic RNA molecule in a variety of human diseases. However, the role of circRNA in bronchopulmonary dysplasia (BPD) has not yet been elucidated. Here, a new circRNA circABCC4 was identified from the Agilent circRNA chip as a differentially expressed circRNA in BPD. The relationship between circABCC4 level and BPD clinicopathological characteristics was analyzed. The function of circABCC4 was evaluated by performing CCK-8 and apoptosis analysis in vitro and BPD model analysis in vivo. RNA immunoprecipitation (RIP), luciferase reporter and rescue experiments were used to elucidate the interaction between circABCC4 and miR-663a. Luciferase reporter assay and rescue experiments were used to elucidate the interaction between PLA2G6 and miR-663a. CircABCC4 and PLA2G6 levels were increased, while miR-663a levels were decreased in the BPD group, compared to the control group. MiR-663a inhibited apoptosis by repressing PLA2G6 expression, while circABCC4 enhanced the apoptosis and inhibited the proliferation of A549 cells by sponging miR-663a and increasing PLA2G6 expression. In conclusion, circABCC4 promotes the evolving of BPD by spongening miR-663a and up-regulating PLA2G6 expression, which makes circABCC4 an ideal molecular target for early diagnosis and intervention of BPD.
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Affiliation(s)
- Yu-Fei Chen
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Dan-Dan Feng
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Sheng-Hua Wu
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hong-Yan Lu
- Department of Pediatrics, The Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Asfia Banu Pasha
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Dhivya Lakshmi Permall
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jia-He Chen
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhong-Yi Sun
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Bing-Jie Li
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Huan Zhou
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yang Yang
- Department of Neonatology, Nanjing Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xiao-Jie Zhang
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xiao-Qing Chen
- Department of Pediatrics, The First Affliated Hospital of Nanjing Medical University, Nanjing, China
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10
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Raghavan S, Baskin DS, Sharpe MA. MP-Pt(IV): A MAOB-Sensitive Mitochondrial-Specific Prodrug for Treating Glioblastoma. Mol Cancer Ther 2020; 19:2445-2453. [PMID: 33033175 DOI: 10.1158/1535-7163.mct-20-0420] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 08/13/2020] [Accepted: 09/23/2020] [Indexed: 11/16/2022]
Abstract
We have previously reported the in vitro and in vivo efficacy of N,N-bis(2-chloroethyl)-2-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)propenamide (MP-MUS), a prodrug that targeted the mitochondria of glioblastoma (GBM). The mitochondrial enzyme, monoamine oxidase B (MAOB), is highly expressed in GBM and oxidizes an uncharged methyl-tetrahydropyridine (MP-) moiety into the mitochondrially targeted cationic form, methyl-pyridinium (P+-). Coupling this MAOB-sensitive group to a nitrogen mustard produced a prodrug that damaged GBM mitochondria and killed GBM cells. Unfortunately, the intrinsic reactivity of the nitrogen mustard group and low solubility of MP-MUS precluded clinical development. In our second-generation prodrug, MP-Pt(IV), we coupled the MP group to an unreactive cisplatin precursor. The enzymatic conversion of MP-Pt(IV) to P+-Pt(IV) was tested using recombinant human MAOA and rhMAOB. The generation of cisplatin from Pt(IV) by ascorbate was studied optically and using mass spectroscopy. Efficacy toward primary GBM cells and tumors was studied in vitro and in an intracranial patient-derived xenograft mice GBM model. Our studies demonstrate that MP-Pt(IV) is selectively activated by MAOB. MP-Pt(IV) is highly toxic toward GBM cells in vitro MP-Pt(IV) toxicity against GBM is potentiated by elevating mitochondrial ascorbate and can be arrested by MAOB inhibition. In in vitro studies, sublethal MP-Pt(IV) doses elevated mitochondrial MAOB levels in surviving GBM cells. MP-Pt(IV) is a potent chemotherapeutic in intracranial patient-derived xenograft mouse models of primary GBM and potentiates both temozolomide and temozolomide-chemoradiation therapies. MP-Pt(IV) was well tolerated and is highly effective against GBM in both in vitro and in vivo models.
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Affiliation(s)
- Sudhir Raghavan
- Kenneth R. Peak Brain and Pituitary Treatment Center and the Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas.,Houston Methodist Research Institute, Houston, Texas
| | - David S Baskin
- Kenneth R. Peak Brain and Pituitary Treatment Center and the Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas. .,Houston Methodist Research Institute, Houston, Texas
| | - Martyn A Sharpe
- Kenneth R. Peak Brain and Pituitary Treatment Center and the Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas. .,Houston Methodist Research Institute, Houston, Texas
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11
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Natarajan V, Chawla R, Mah T, Vivekanandan R, Tan SY, Sato PY, Mallilankaraman K. Mitochondrial Dysfunction in Age-Related Metabolic Disorders. Proteomics 2020; 20:e1800404. [PMID: 32131138 DOI: 10.1002/pmic.201800404] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 02/07/2020] [Indexed: 12/16/2022]
Abstract
Aging is a natural biological process in living organisms characterized by receding bioenergetics. Mitochondria are crucial for cellular bioenergetics and thus an important contributor to age-related energetics deterioration. In addition, mitochondria play a major role in calcium signaling, redox homeostasis, and thermogenesis making this organelle a major cellular component that dictates the fate of a cell. To maintain its quantity and quality, mitochondria undergo multiple processes such as fission, fusion, and mitophagy to eliminate or replace damaged mitochondria. While this bioenergetics machinery is properly protected, the functional decline associated with age and age-related metabolic diseases is mostly a result of failure in such protective mechanisms. In addition, metabolic by-products like reactive oxygen species also aid in this destructive pathway. Mitochondrial dysfunction has always been thought to be associated with diseases. Moreover, studies in recent years have pointed out that aging contributes to the decay of mitochondrial health by promoting imbalances in key mitochondrial-regulated pathways. Hence, it is crucial to understand the nexus of mitochondrial dysfunction in age-related diseases. This review focuses on various aspects of basic mitochondrial biology and its status in aging and age-related metabolic diseases.
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Affiliation(s)
- Venkateswaran Natarajan
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Ritu Chawla
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Tania Mah
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Rajesh Vivekanandan
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Shu Yi Tan
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Priscila Y Sato
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, 19102-1902, USA
| | - Karthik Mallilankaraman
- Mitochondrial Physiology and Metabolism Lab, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.,Center for Healthy Longevity, National University Health System, Singapore, 119228, Singapore
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12
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Ježek P, Jabůrek M, Plecitá-Hlavatá L. Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes. Antioxid Redox Signal 2019; 31:722-751. [PMID: 30450940 PMCID: PMC6708273 DOI: 10.1089/ars.2018.7656] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 11/05/2018] [Indexed: 12/14/2022]
Abstract
Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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13
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Ježek P, Jabůrek M, Porter RK. Uncoupling mechanism and redox regulation of mitochondrial uncoupling protein 1 (UCP1). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:259-269. [DOI: 10.1016/j.bbabio.2018.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 10/15/2018] [Accepted: 11/07/2018] [Indexed: 01/11/2023]
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14
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Ježek P, Holendová B, Garlid KD, Jabůrek M. Mitochondrial Uncoupling Proteins: Subtle Regulators of Cellular Redox Signaling. Antioxid Redox Signal 2018; 29:667-714. [PMID: 29351723 PMCID: PMC6071544 DOI: 10.1089/ars.2017.7225] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE Mitochondria are the energetic, metabolic, redox, and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics, and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the mentioned aspects, being involved in numerous physiological events including redox signaling. Recent Advances: UCP2 structure, including purine nucleotide and fatty acid (FA) binding sites, strongly support the FA cycling mechanism: UCP2 expels FA anions, whereas uncoupling is achieved by the membrane backflux of protonated FA. Nascent FAs, cleaved by phospholipases, are preferential. The resulting Δp dissipation decreases superoxide formation dependent on Δp. UCP-mediated antioxidant protection and its impairment are expected to play a major role in cell physiology and pathology. Moreover, UCP2-mediated aspartate, oxaloacetate, and malate antiport with phosphate is expected to alter metabolism of cancer cells. CRITICAL ISSUES A wide range of UCP antioxidant effects and participations in redox signaling have been reported; however, mechanisms of UCP activation are still debated. Switching off/on the UCP2 protonophoretic function might serve as redox signaling either by employing/releasing the extra capacity of cell antioxidant systems or by directly increasing/decreasing mitochondrial superoxide sources. Rapid UCP2 degradation, FA levels, elevation of purine nucleotides, decreased Mg2+, or increased pyruvate accumulation may initiate UCP-mediated redox signaling. FUTURE DIRECTIONS Issues such as UCP2 participation in glucose sensing, neuronal (synaptic) function, and immune cell activation should be elucidated. Antioxid. Redox Signal. 29, 667-714.
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Affiliation(s)
- Petr Ježek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Blanka Holendová
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Keith D Garlid
- 2 UCLA Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA , Los Angeles, California
| | - Martin Jabůrek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
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15
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Chen K, Xu Z, Liu Y, Wang Z, Li Y, Xu X, Chen C, Xia T, Liao Q, Yao Y, Zeng C, He D, Yang Y, Tan T, Yi J, Zhou J, Zhu H, Ma J, Zeng C. Irisin protects mitochondria function during pulmonary ischemia/reperfusion injury. Sci Transl Med 2018; 9:9/418/eaao6298. [PMID: 29187642 DOI: 10.1126/scitranslmed.aao6298] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 08/10/2017] [Accepted: 10/20/2017] [Indexed: 12/13/2022]
Abstract
Limb remote ischemic preconditioning (RIPC) is an effective means of protection against ischemia/reperfusion (IR)-induced injury to multiple organs. Many studies are focused on identifying endocrine mechanisms that underlie the cross-talk between muscle and RIPC-mediated organ protection. We report that RIPC releases irisin, a myokine derived from the extracellular portion of fibronectin domain-containing 5 protein (FNDC5) in skeletal muscle, to protect against injury to the lung. Human patients with neonatal respiratory distress syndrome show reduced concentrations of irisin in the serum and increased irisin concentrations in the bronchoalveolar lavage fluid, suggesting transfer of irisin from circulation to the lung under physiologic stress. In mice, application of brief periods of ischemia preconditioning stimulates release of irisin into circulation and transfer of irisin to the lung subjected to IR injury. Irisin, via lipid raft-mediated endocytosis, enters alveolar cells and targets mitochondria. Interaction between irisin and mitochondrial uncoupling protein 2 (UCP2) allows for prevention of IR-induced oxidative stress and preservation of mitochondrial function. Animal model studies show that intravenous administration of exogenous irisin protects against IR-induced injury to the lung via improvement of mitochondrial function, whereas in UCP2-deficient mice or in the presence of a UCP2 inhibitor, the protective effect of irisin is compromised. These results demonstrate that irisin is a myokine that facilitates RIPC-mediated lung protection. Targeting the action of irisin in mitochondria presents a potential therapeutic intervention for pulmonary IR injury.
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Affiliation(s)
- Ken Chen
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China.,Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Zaicheng Xu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Yukai Liu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Zhen Wang
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Yu Li
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Xuefei Xu
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Caiyu Chen
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Tianyang Xia
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Qiao Liao
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Yonggang Yao
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Cindy Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Duofen He
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China.,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
| | - Yongjian Yang
- Department of Cardiology, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Tao Tan
- Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jianxun Yi
- Department of Physiology, Kansas City University, Kansas City, MO 64106, USA
| | - Jingsong Zhou
- Department of Physiology, Kansas City University, Kansas City, MO 64106, USA
| | - Hua Zhu
- Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jianjie Ma
- Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042, P.R. China. .,Chongqing Institute of Cardiology, Chongqing 400042, P.R. China
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Jabůrek M, Ježek J, Ježek P. Cytoprotective activity of mitochondrial uncoupling protein-2 in lung and spleen. FEBS Open Bio 2018; 8:692-701. [PMID: 29632821 PMCID: PMC5881546 DOI: 10.1002/2211-5463.12410] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/06/2018] [Accepted: 02/12/2018] [Indexed: 01/14/2023] Open
Abstract
Mitochondrial uncoupling protein‐2 (UCP2) mediates free fatty acid (FA)‐dependent H+ translocation across the inner mitochondrial membrane (IMM), which leads to acceleration of respiration and suppression of mitochondrial superoxide formation. Redox‐activated mitochondrial phospholipase A2 (mt‐iPLA2γ) cleaves FAs from the IMM and has been shown to acts in synergy with UCP2. Here, we tested the mechanism of mt‐iPLA2γ‐dependent UCP2‐mediated antioxidant protection using lipopolysaccharide (LPS)‐induced pro‐inflammatory and pro‐oxidative responses and their acute influence on the overall oxidative stress reflected by protein carbonylation in murine lung and spleen mitochondria and tissue homogenates. We provided challenges either by blocking the mt‐iPLA2γ function by the selective inhibitor R‐bromoenol lactone (R‐BEL) or by removing UCP2 by genetic ablation. We found that the basal levels of protein carbonyls in lung and spleen tissues and isolated mitochondria were higher in UCP2‐knockout mice relative to the wild‐type (wt) controls. The administration of R‐BEL increased protein carbonyl levels in wt but not in UCP2‐knockout (UCP2‐KO) mice. LPS further increased the protein carbonyl levels in UCP2‐KO mice, which correlated with protein carbonyl levels determined in wt mice treated with R‐BEL. These results are consistent with the UCP2/mt‐iPLA2γ antioxidant mechanisms in these tissues and support the existence of UCP2‐synergic mt‐iPLA2γ‐dependent cytoprotective mechanism in vivo.
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Affiliation(s)
- Martin Jabůrek
- Department of Mitochondrial Physiology Institute of Physiology Academy of Sciences Prague Czech Republic
| | - Jan Ježek
- Department of Mitochondrial Physiology Institute of Physiology Academy of Sciences Prague Czech Republic
| | - Petr Ježek
- Department of Mitochondrial Physiology Institute of Physiology Academy of Sciences Prague Czech Republic
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17
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Lowered iPLA2γ activity causes increased mitochondrial lipid peroxidation and mitochondrial dysfunction in a rotenone-induced model of Parkinson's disease. Exp Neurol 2018; 300:74-86. [DOI: 10.1016/j.expneurol.2017.10.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 12/25/2022]
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18
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Targeting of stress response pathways in the prevention and treatment of cancer. Biotechnol Adv 2018; 36:583-602. [PMID: 29339119 DOI: 10.1016/j.biotechadv.2018.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 01/08/2018] [Accepted: 01/10/2018] [Indexed: 12/12/2022]
Abstract
The hallmarks of tumor tissue are not only genetic aberrations but also the presence of metabolic and oxidative stress as a result of hypoxia and lactic acidosis. The stress activates several prosurvival pathways including metabolic remodeling, autophagy, antioxidant response, mitohormesis, and glutaminolysis, whose upregulation in tumors is associated with a poor survival of patients, while their activation in healthy tissue with statins, metformin, physical activity, and natural compounds prevents carcinogenesis. This review emphasizes the dual role of stress response pathways in cancer and suggests the integrative understanding as a basis for the development of rational therapy targeting the stress response.
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19
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Neurons and astrocytes in an infantile neuroaxonal dystrophy (INAD) mouse model show characteristic alterations in glutamate-induced Ca 2+ signaling. Neurochem Int 2017; 108:121-132. [DOI: 10.1016/j.neuint.2017.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 03/03/2017] [Accepted: 03/03/2017] [Indexed: 01/01/2023]
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20
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Plecitá-Hlavatá L, Ježek P. Integration of superoxide formation and cristae morphology for mitochondrial redox signaling. Int J Biochem Cell Biol 2016; 80:31-50. [PMID: 27640755 DOI: 10.1016/j.biocel.2016.09.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 12/16/2022]
Abstract
The mitochondrial network provides the central cell's energetic and regulatory unit, which besides ATP and metabolite production participates in cellular signaling through regulated reactive oxygen species (ROS) production and various protein/ion fluxes. The inner membrane forms extensive folds, called cristae, i.e. cavities enfolded from and situated perpendicularly to its inner boundary membrane portion, which encompasses an inner cylinder within the outer membrane tubule. Mitochondrial cristae ultramorphology reflects various metabolic, physiological or pathological states. Since the mitochondrion is typically a predominant superoxide source and generated ROS also serve for the creation of information redox signals, we review known relationships between ROS generation within the respiratory chain complexes of cristae and cristae morphology. Notably, it is emphasized that cristae shape is governed by ATP-synthase dimers, MICOS complexes, OPA1 isoforms and the umbrella of their regulation, and also dependent on local protonmotive force (electrical potential component) in cristae. Cristae are also affected by redox-sensitive kinases/phosphatases or p66SHC. ATP-synthase dimers decrease in the inflated intracristal space, diminishing pH and hypothetically having minimal superoxide formation. Matrix-released signaling superoxide/H2O2 is predominantly integrated along mitochondrial tubules, whereas the diffusion of intracristal signaling ROS species is controlled by crista junctions, the widening of which enables specific retrograde redox signaling such as during hypoxic cell adaptation. Other physiological cases of H2O2 release from the mitochondrion include the modulation of insulin release in pancreatic β-cells, enhancement of insulin signaling in peripheral tissues, signaling by T-cell receptors, retrograde signaling during the cell cycle and cell differentiation, specifically that of adipocytes.
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Affiliation(s)
- Lydie Plecitá-Hlavatá
- Department of Membrane Transport Biophysics, No.75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Petr Ježek
- Department of Membrane Transport Biophysics, No.75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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21
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Hyperbilirubinemia Protects against Aging-Associated Inflammation and Metabolic Deterioration. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:6190609. [PMID: 27547293 PMCID: PMC4983390 DOI: 10.1155/2016/6190609] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/31/2016] [Accepted: 06/07/2016] [Indexed: 12/16/2022]
Abstract
Mild constitutive hyperbilirubinemia is associated with a reduced risk of cardiovascular diseases, diabetes, and cancer. Since these pathologies are associated with aging, inflammation, and oxidative stress, we investigated whether hyperbilirubinemia interferes with ROS homeostasis in cell cultures and with inflammation, senescence, and mitochondrial dysfunction in aged rats. Human embryonic kidney cells and rat primary fibroblasts showed a dose-dependent decrease in the ratio of oxidized/reduced glutathione, intracellular H2O2 levels, and mitochondrial ROS production, with increasing bilirubin concentrations in the culture media. Compared to their normobilirubinemic siblings, aged hyperbilirubinemic Gunn rats showed significantly smaller amounts of visceral fat, better glucose tolerance, and decreased serum levels of proinflammatory cytokines TNFα, IL-1β, and IL-18. Simultaneously, livers from Gunn rats showed decreased expression of senescence markers and cell cycle inhibitors p21 and p16. Mitochondria from aged Gunn rats showed higher respiration and lower H2O2 production compared to controls. In conclusion, we demonstrated that mildly elevated serum bilirubin is generally associated with attenuation of oxidative stress and with better anthropometric parameters, decreased inflammatory status, increased glucose tolerance, fewer signs of cellular senescence, and enhanced mitochondrial function in aged rats.
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Ježek J, Dlasková A, Zelenka J, Jabůrek M, Ježek P. H₂O₂-Activated Mitochondrial Phospholipase iPLA₂γ Prevents Lipotoxic Oxidative Stress in Synergy with UCP2, Amplifies Signaling via G-Protein-Coupled Receptor GPR40, and Regulates Insulin Secretion in Pancreatic β-Cells. Antioxid Redox Signal 2015; 23:958-72. [PMID: 25925080 PMCID: PMC4623989 DOI: 10.1089/ars.2014.6195] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIMS Pancreatic β-cell chronic lipotoxicity evolves from acute free fatty acid (FA)-mediated oxidative stress, unprotected by antioxidant mechanisms. Since mitochondrial uncoupling protein-2 (UCP2) plays antioxidant and insulin-regulating roles in pancreatic β-cells, we tested our hypothesis, that UCP2-mediated uncoupling attenuating mitochondrial superoxide production is initiated by FA release due to a direct H2O2-induced activation of mitochondrial phospholipase iPLA2γ. RESULTS Pro-oxidant tert-butylhydroperoxide increased respiration, decreased membrane potential and mitochondrial matrix superoxide release rates of control but not UCP2- or iPLA2γ-silenced INS-1E cells. iPLA2γ/UCP2-mediated uncoupling was alternatively activated by an H2O2 burst, resulting from palmitic acid (PA) β-oxidation, and it was prevented by antioxidants or catalase overexpression. Exclusively, nascent FAs that cleaved off phospholipids by iPLA2γ were capable of activating UCP2, indicating that the previously reported direct redox UCP2 activation is actually indirect. Glucose-stimulated insulin release was not affected by UCP2 or iPLA2γ silencing, unless pro-oxidant activation had taken place. PA augmented insulin secretion via G-protein-coupled receptor 40 (GPR40), stimulated by iPLA2γ-cleaved FAs (absent after GPR40 silencing). INNOVATION AND CONCLUSION The iPLA2γ/UCP2 synergy provides a feedback antioxidant mechanism preventing oxidative stress by physiological FA intake in pancreatic β-cells, regulating glucose-, FA-, and redox-stimulated insulin secretion. iPLA2γ is regulated by exogenous FA via β-oxidation causing H2O2 signaling, while FAs are cleaved off phospholipids, subsequently acting as amplifying messengers for GPR40. Hence, iPLA2γ acts in eminent physiological redox signaling, the impairment of which results in the lack of antilipotoxic defense and contributes to chronic lipotoxicity.
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Affiliation(s)
- Jan Ježek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jaroslav Zelenka
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Petr Ježek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Rauckhorst AJ, Pfeiffer DR, Broekemeier KM. The iPLA2γ is identified as the membrane potential sensitive phospholipase in liver mitochondria. FEBS Lett 2015. [DOI: 10.1016/j.febslet.2015.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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24
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Hoang T, Kuljanin M, Smith MD, Jelokhani-Niaraki M. A biophysical study on molecular physiology of the uncoupling proteins of the central nervous system. Biosci Rep 2015; 35:e00226. [PMID: 26182433 PMCID: PMC4613710 DOI: 10.1042/bsr20150130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 06/04/2015] [Indexed: 01/16/2023] Open
Abstract
Mitochondrial inner membrane uncoupling proteins (UCPs) facilitate transmembrane (TM) proton flux and consequently reduce the membrane potential and ATP production. It has been proposed that the three neuronal human UCPs (UCP2, UCP4 and UCP5) in the central nervous system (CNS) play significant roles in reducing cellular oxidative stress. However, the structure and ion transport mechanism of these proteins remain relatively unexplored. Recently, we reported a novel expression system for obtaining functionally folded UCP1 in bacterial membranes and applied this system to obtain highly pure neuronal UCPs in high yields. In the present study, we report on the structure and function of the three neuronal UCP homologues. Reconstituted neuronal UCPs were dominantly helical in lipid membranes and transported protons in the presence of physiologically-relevant fatty acid (FA) activators. Under similar conditions, all neuronal UCPs also exhibited chloride transport activities that were partially inhibited by FAs. CD, fluorescence and MS measurements and semi-native gel electrophoresis collectively suggest that the reconstituted proteins self-associate in the lipid membranes. Based on SDS titration experiments and other evidence, a general molecular model for the monomeric, dimeric and tetrameric functional forms of UCPs in lipid membranes is proposed. In addition to their shared structural and ion transport features, neuronal UCPs differ in their conformations and proton transport activities (and possibly mechanism) in the presence of different FA activators. The differences in FA-activated UCP-mediated proton transport could serve as an essential factor in understanding and differentiating the physiological roles of UCP homologues in the CNS.
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Affiliation(s)
- Tuan Hoang
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada, N2L 3C5 Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Miljan Kuljanin
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada, N2L 3C5
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada, N2L 3C5 Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
| | - Masoud Jelokhani-Niaraki
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada, N2L 3C5 Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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25
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Tyurina YY, Polimova AM, Maciel E, Tyurin VA, Kapralova VI, Winnica DE, Vikulina AS, Domingues RM, McCoy J, Sanders LH, Bayır H, Greenamyre JT, Kagan VE. LC/MS analysis of cardiolipins in substantia nigra and plasma of rotenone-treated rats: Implication for mitochondrial dysfunction in Parkinson's disease. Free Radic Res 2015; 49:681-91. [PMID: 25740198 PMCID: PMC4430340 DOI: 10.3109/10715762.2015.1005085] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Exposure to rotenone in vivo results in selective degeneration of dopaminergic neurons and development of neuropathologic features of Parkinson's disease (PD). As rotenone acts as an inhibitor of mitochondrial respiratory complex I, we employed oxidative lipidomics to assess oxidative metabolism of a mitochondria-specific phospholipid, cardiolipin (CL), in substantia nigra (SN) of exposed animals. We found a significant reduction in oxidizable polyunsaturated fatty acid (PUFA)-containing CL molecular species. We further revealed increased contents of mono-oxygenated CL species at late stages of the exposure. Notably, linoleic acid in sn-1 position was the major oxidation substrate yielding its mono-hydroxy- and epoxy-derivatives whereas more readily "oxidizable" fatty acid residues (arachidonic and docosahexaenoic acids) remained non-oxidized. Elevated levels of PUFA CLs were detected in plasma of rats exposed to rotenone. Characterization of oxidatively modified CL molecular species in SN and detection of PUFA-containing CL species in plasma may contribute to better understanding of the PD pathogenesis and lead to the development of new biomarkers of mitochondrial dysfunction associated with this disease.
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Affiliation(s)
- Yulia Y. Tyurina
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Anastasia M. Polimova
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Biophysics, Faculty of Fundamental Medicine, MV Lomonosov Moscow State University, Moscow 119192, Russia
| | - Elisabete Maciel
- Mass Spectrometry Center, University of Aveiro, 3810-193 Aveiro, Portugal
- QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Vladimir A. Tyurin
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Valentina I. Kapralova
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Daniel E. Winnica
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Anna S. Vikulina
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Rosario M. Domingues
- Mass Spectrometry Center, University of Aveiro, 3810-193 Aveiro, Portugal
- QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Jennifer McCoy
- Department of Neurology, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Laurie H. Sanders
- Department of Neurology, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | - Hülya Bayır
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh PA, 15219, USA
| | | | - Valerian E. Kagan
- Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh PA, 15219, USA
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26
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Uncoupling protein 2 regulates palmitic acid-induced hepatoma cell autophagy. BIOMED RESEARCH INTERNATIONAL 2014; 2014:810401. [PMID: 25512910 PMCID: PMC4143590 DOI: 10.1155/2014/810401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/29/2014] [Accepted: 06/30/2014] [Indexed: 01/11/2023]
Abstract
Mitochondrial uncoupling protein 2 (UCP2) is suggested to have a role in the development of nonalcoholic steatohepatitis (NASH). However, the mechanism remains unclear. Autophagy is an important mediator of many pathological responses. This study aims to investigate the relationship between UCP2 and hepatoma cells autophagy in palmitic acid- (PA-) induced lipotoxicity. H4IIE cells were treated with palmitic acid (PA), and cell autophagy and apoptosis were examined. UCP2 expression, in association with LC3-II and caspase-3, which are indicators of cell autophagy and apoptosis, respectively,was measured. Results demonstrated that UCP2 was associated with autophagy during PA-induced hepatic carcinoma cells injury. Tests on reactive oxygen species (ROS) showed that UCP2 overexpression strongly decreases PA-induced ROS production and apoptosis. Conversely, UCP2 inhibition by genipin or UCP2 mRNA silencing enhances PA-induced ROS production and apoptosis. Autophagy partially participates in this progress. Moreover, UCP2 was associated with ATP synthesis during PA-induced autophagy. In conclusion, increasing UCP2 expression in hepatoma cells may contribute to cell autophagy and antiapoptotic as result of fatty acid injury. Our results may bring new insights for potential NASH therapies.
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Nordmann C, Strokin M, Schönfeld P, Reiser G. Putative roles of Ca(2+) -independent phospholipase A2 in respiratory chain-associated ROS production in brain mitochondria: influence of docosahexaenoic acid and bromoenol lactone. J Neurochem 2014; 131:163-76. [PMID: 24923354 DOI: 10.1111/jnc.12789] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/05/2014] [Accepted: 06/10/2014] [Indexed: 11/28/2022]
Abstract
Ca(2+) -independent phospholipase A2 (iPLA2 ) is hypothesized to control mitochondrial reactive oxygen species (ROS) generation. Here, we modulated the influence of iPLA2 -induced liberation of non-esterified free fatty acids on ROS generation associated with the electron transport chain. We demonstrate enzymatic activity of membrane-associated iPLA2 in native, energized rat brain mitochondria (RBM). Theoretically, enhanced liberation of free fatty acids by iPLA2 modulates mitochondrial ROS generation, either attenuating the reversed electron transport (RET) or deregulating the forward electron transport of electron transport chain. For mimicking such conditions, we probed the effect of docosahexaenoic acid (DHA), a major iPLA2 product on ROS generation. We demonstrate that the adenine nucleotide translocase partly mediates DHA-induced uncoupling, and that low micromolar DHA concentrations diminish RET-dependent ROS generation. Uncoupling proteins have no effect, but the adenine nucleotide translocase inhibitor carboxyatractyloside attenuates DHA-linked uncoupling effect on RET-dependent ROS generation. Under physiological conditions of forward electron transport, low micromolar DHA stimulates ROS generation. Finally, exposure of RBM to the iPLA2 inhibitor bromoenol lactone (BEL) enhanced ROS generation. BEL diminished RBM glutathione content. BEL-treated RBM exhibits reduced Ca(2+) retention capacity and partial depolarization. Thus, we rebut the view that iPLA2 attenuates oxidative stress in brain mitochondria. However, the iPLA2 inhibitor BEL has detrimental activities on energy-dependent mitochondrial functions. The Ca(2+) -independent phospholipase A2 (iPLA2 ), a FFA (free fatty acids)-generating membrane-attached mitochondrial phospholipase, is potential to regulate ROS (reactive oxygen species) generation by mitochondria. FFA can either decrease reversed electron transport (RET)-linked or enhance forward electron transport (FET)-linked ROS generation. In the physiological mode of FET, iPLA2 activity increases ROS generation. The iPLA2 inhibitor BEL exerts detrimental effects on energy-dependent mitochondrial functions.
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Affiliation(s)
- Caroline Nordmann
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Mikhail Strokin
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Peter Schönfeld
- Institut für Biochemie und Zellbiologie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
| | - Georg Reiser
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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28
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Tang SE, Wu CP, Wu SY, Peng CK, Perng WC, Kang BH, Chu SJ, Huang KL. Stanniocalcin-1 ameliorates lipopolysaccharide-induced pulmonary oxidative stress, inflammation, and apoptosis in mice. Free Radic Biol Med 2014; 71:321-331. [PMID: 24685991 DOI: 10.1016/j.freeradbiomed.2014.03.034] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 03/20/2014] [Accepted: 03/22/2014] [Indexed: 12/20/2022]
Abstract
Stanniocalcin-1 (STC1) is an endogenous glycoprotein whose anti-inflammatory effects occur through induction of uncoupling proteins to reduce oxidative stress. In this study, we tested the hypothesis that exogenous recombinant human STC1 (rhSTC1) protects against lipopolysaccharide (LPS)-induced acute lung injury in mice. Anesthetized C57BL/6 mice underwent intratracheal spraying of LPS (20 µg/10 g body wt), and lung injury was assessed 24h later by analyzing pulmonary edema, bronchoalveolar lavage fluid, and lung histopathology. Lung inflammation, oxidative stress, and expression of STC1 and its downstream uncoupling protein 2 (UCP2) were analyzed at specific time points. Expression of UCP2 was suppressed initially but was subsequently upregulated after STC1 elevation in response to intratracheal administration of LPS. Intratracheal rhSTC1 treatment 1h before or after LPS spraying significantly attenuated pulmonary inflammation, oxidative stress, cell apoptosis, and acute lung injury. Pretreatment with STC1 short interfering RNA 48 h before LPS spraying inhibited the expression of STC1 and UCP2 and significantly increased the extent of lung injury. These findings suggest that STC1 is an endogenous stress protein that may counteract LPS-induced lung injury by inhibiting the inflammatory cascade and inducing antioxidant and antiapoptotic mechanisms. However, the potential clinical application of STC1 and the direct linkage between UCP2 and LPS-induced lung injury remain to be further investigated.
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Affiliation(s)
- Shih-En Tang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei 114, Taiwan; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Chin-Pyng Wu
- Department of Critical Care Medicine, Landseed Hospital, Taoyuan, Taiwan
| | - Shu-Yu Wu
- Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei 114, Taiwan
| | - Chung-Kan Peng
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Wann-Cherng Perng
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Bor-Hwang Kang
- Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei 114, Taiwan
| | - Shi-Jye Chu
- Division of Rheumatology, Immunology, and Allergy, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan.
| | - Kun-Lun Huang
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan; Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei 114, Taiwan.
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29
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Yang JT, Li ZL, Wu JY, Lu FJ, Chen CH. An oxidative stress mechanism of shikonin in human glioma cells. PLoS One 2014; 9:e94180. [PMID: 24714453 PMCID: PMC3979747 DOI: 10.1371/journal.pone.0094180] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 03/13/2014] [Indexed: 11/18/2022] Open
Abstract
Shikonin is a quinone-containing natural product that induces the apoptotic death of some cancer cell lines in culture through increasing intracellular reactive oxygen species (ROS). Quinone-based drugs have shown potential in the clinic, making shikonin an interesting compound to study. Our previous study found that shikonin induces apoptosis in neuroblastoma by induction of ROS, but its mechanism of action and scope of activity are unknown. In this study, we investigated the mode of oxidative stress of shikonin in human glioma cells. ROS induction by shikonin was of mitochondrial origin, as demonstrated by detection of superoxide with MitoSOX Red. Pre-incubation of shikonin with inhibitors of different complexes of the respiratory chain suggested that shikonin-induced ROS production occurred via complex II. In addition, NADPH oxidase and lipooxygenase are two other main ROS-generated sites in shikonin treatment. ROS production by shikonin resulted in the inhibition of nuclear translocation of Nrf2. Stable overexpression of Nrf2 in glioma cells inhibited ROS generation by shikonin. ROS generation from mitochondrial complex II, NADPH oxidase and lipooxygenase is likely the primary mechanism by which shikonin induces apoptosis in glioma cells. These findings also have relevance to the development of certain ROS producers as anti-cancer agents. These, along with shikonin have potential as novel chemotherapeutic agents on human glioma.
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Affiliation(s)
- Jen-Tsung Yang
- Department of Neurosurgery, Chang Gung Memorial Hospital at Chiayi, Chia-Yi 613, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, ROC
| | - Zih-Ling Li
- Department of Neurosurgery, Chang Gung Memorial Hospital at Chiayi, Chia-Yi 613, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, ROC
- Department of Microbiology, Immunology and Biopharmaceuticals, College of Life Sciences, National Chiayi University, Chiayi City, Taiwan, ROC
| | - Jin-Yi Wu
- Department of Microbiology, Immunology and Biopharmaceuticals, College of Life Sciences, National Chiayi University, Chiayi City, Taiwan, ROC
| | - Fung-Jou Lu
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
| | - Ching-Hsein Chen
- Department of Microbiology, Immunology and Biopharmaceuticals, College of Life Sciences, National Chiayi University, Chiayi City, Taiwan, ROC
- * E-mail:
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30
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Rauckhorst AJ, Broekemeier KM, Pfeiffer DR. Regulation of the Ca(2+)-independent phospholipase A2 in liver mitochondria by changes in the energetic state. J Lipid Res 2014; 55:826-36. [PMID: 24586040 DOI: 10.1194/jlr.m043307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of electron transport chain redox status on activity of the mitochondrial Ca(2+)-independent phospholipase A2 (iPLA2) has been examined. When oxidizing NAD-linked substrates, the enzyme is not active unless deenergization occurs. Uncoupler, rotenone, antimycin A, and cyanide are equally effective at upregulating the enzyme, while oligomycin is ineffective. Thenoyltrifluoroacetone causes deenergization and activates the enzyme, but only if succinate is the respiratory substrate. These findings show that the mitochondrial iPLA2 responds to the energetic state overall, rather than to the redox status of individual electron transport chain complexes. With NAD-linked substrates, and using rotenone to deenergize, iPLA2 activation can be reversed by adding succinate to reestablish a membrane potential. For this purpose, ascorbate plus N,N,N'N'-tetramethyl-phenylenediamine can be used instead of succinate and is equally effective. With succinate as substrate, the membrane potential can be reduced in a graded and stable fashion by adding increasing concentrations of malonate, which is a competitive inhibitor of succinate utilization. A partial and stable activation of the iPLA2 accompanies partial deenergization. These findings suggest that in addition to the several functions that have been proposed, the mitochondrial iPLA2 may help to coordinate local capillary blood flow with changing energy demands.
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Affiliation(s)
- Adam J Rauckhorst
- Departments of Molecular and Cellular Biochemistry Ohio State University, Columbus, OH 43210
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31
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JEŽEK P, OLEJÁR T, SMOLKOVÁ K, JEŽEK J, DLASKOVÁ A, PLECITÁ-HLAVATÁ L, ZELENKA J, ŠPAČEK T, ENGSTOVÁ H, PAJUELO REGUERA D, JABŮREK M. Antioxidant and Regulatory Role of Mitochondrial Uncoupling Protein UCP2 in Pancreatic β-cells. Physiol Res 2014; 63:S73-91. [DOI: 10.33549/physiolres.932633] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on brown adipose tissue and its hallmark protein, mitochondrial uncoupling protein UCP1, has been conducted for half a century and has been traditionally studied in the Institute of Physiology (AS CR, Prague), likewise UCP2 residing in multiple tissues for the last two decades. Our group has significantly contributed to the elucidation of UCP uncoupling mechanism, fully dependent on free fatty acids (FFAs) within the inner mitochondrial membrane. Now we review UCP2 physiological roles emphasizing its roles in pancreatic β-cells, such as antioxidant role, possible tuning of redox homeostasis (consequently UCP2 participation in redox regulations), and fine regulation of glucose-stimulated insulin secretion (GSIS). For example, NADPH has been firmly established as being a modulator of GSIS and since UCP2 may influence redox homeostasis, it likely affects NADPH levels. We also point out the role of phospholipase iPLA2 isoform in providing FFAs for the UCP2 antioxidant function. Such initiation of mild uncoupling hypothetically precedes lipotoxicity in pancreatic β-cells until it reaches the pathological threshold, after which the antioxidant role of UCP2 can be no more cell-protective, for example due to oxidative stress-accumulated mutations in mtDNA. These mechanisms, together with impaired autocrine insulin function belong to important causes of Type 2 diabetes etiology.
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Affiliation(s)
- P. JEŽEK
- Department of Membrane Transport Biophysics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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