1
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Morelli AM, Scholkmann F. Should the standard model of cellular energy metabolism be reconsidered? Possible coupling between the pentose phosphate pathway, glycolysis and extra-mitochondrial oxidative phosphorylation. Biochimie 2024; 221:99-109. [PMID: 38307246 DOI: 10.1016/j.biochi.2024.01.018] [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: 08/07/2023] [Revised: 01/17/2024] [Accepted: 01/30/2024] [Indexed: 02/04/2024]
Abstract
The process of cellular respiration occurs for energy production through catabolic reactions, generally with glucose as the first process step. In the present work, we introduce a novel concept for understanding this process, based on our conclusion that glucose metabolism is coupled to the pentose phosphate pathway (PPP) and extra-mitochondrial oxidative phosphorylation in a closed-loop process. According to the current standard model of glycolysis, glucose is first converted to glucose 6-phosphate (glucose 6-P) and then to fructose 6-phosphate, glyceraldehyde 3-phosphate and pyruvate, which then enters the Krebs cycle in the mitochondria. However, it is more likely that the pyruvate will be converted to lactate. In the PPP, glucose 6-P is branched off from glycolysis and used to produce NADPH and ribulose 5-phosphate (ribulose 5-P). Ribulose 5-P can be converted to fructose 6-P and glyceraldehyde 3-P. In our view, a circular process can take place in which the ribulose 5-P produced by the PPP enters the glycolysis pathway and is then retrogradely converted to glucose 6-P. This process is repeated several times until the complete degradation of glucose 6-P. The role of mitochondria in this process is to degrade lipids by beta-oxidation and produce acetyl-CoA; the function of producing ATP appears to be only secondary. This proposed new concept of cellular bioenergetics allows the resolution of some previously unresolved controversies related to cellular respiration and provides a deeper understanding of metabolic processes in the cell, including new insights into the Warburg effect.
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Affiliation(s)
| | - Felix Scholkmann
- Neurophotonics and Biosignal Processing Research Group, Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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2
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Cai L, Xia M, Zhang F. Redox Regulation of Immunometabolism in Microglia Underpinning Diabetic Retinopathy. Antioxidants (Basel) 2024; 13:423. [PMID: 38671871 PMCID: PMC11047590 DOI: 10.3390/antiox13040423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/24/2024] [Accepted: 03/28/2024] [Indexed: 04/28/2024] Open
Abstract
Diabetic retinopathy (DR) is the leading cause of visual impairment and blindness among the working-age population. Microglia, resident immune cells in the retina, are recognized as crucial drivers in the DR process. Microglia activation is a tightly regulated immunometabolic process. In the early stages of DR, the M1 phenotype commonly shifts from oxidative phosphorylation to aerobic glycolysis for energy production. Emerging evidence suggests that microglia in DR not only engage specific metabolic pathways but also rearrange their oxidation-reduction (redox) system. This redox adaptation supports metabolic reprogramming and offers potential therapeutic strategies using antioxidants. Here, we provide an overview of recent insights into the involvement of reactive oxygen species and the distinct roles played by key cellular antioxidant pathways, including the NADPH oxidase 2 system, which promotes glycolysis via enhanced glucose transporter 4 translocation to the cell membrane through the AKT/mTOR pathway, as well as the involvement of the thioredoxin and nuclear factor E2-related factor 2 antioxidant systems, which maintain microglia in an anti-inflammatory state. Therefore, we highlight the potential for targeting the modulation of microglial redox metabolism to offer new concepts for DR treatment.
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Affiliation(s)
- Luwei Cai
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China; (L.C.); (M.X.)
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
- Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai 200080, China
- Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai 200080, China
| | - Mengxue Xia
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China; (L.C.); (M.X.)
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
- Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai 200080, China
- Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai 200080, China
| | - Fang Zhang
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China; (L.C.); (M.X.)
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
- Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai 200080, China
- Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai 200080, China
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3
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García-Montalvo IA, Matías-Pérez D, Hernández-Bautista E, Pérez-Campos E. Inclusion of carotenoids in dietary habits as an alternative to prevent age-related macular degeneration. Front Nutr 2023; 9:1063517. [PMID: 36698471 PMCID: PMC9868752 DOI: 10.3389/fnut.2022.1063517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 12/14/2022] [Indexed: 01/11/2023] Open
Affiliation(s)
- Iván Antonio García-Montalvo
- Division of Graduate Studies and Research, National Institute of Technology of Mexico/Technological Institute of Oaxaca, Oaxaca, Mexico
| | - Diana Matías-Pérez
- Division of Graduate Studies and Research, National Institute of Technology of Mexico/Technological Institute of Oaxaca, Oaxaca, Mexico
| | - Emilio Hernández-Bautista
- Division of Graduate Studies and Research, National Institute of Technology of Mexico/Technological Institute of Oaxaca, Oaxaca, Mexico
| | - Eduardo Pérez-Campos
- Division of Graduate Studies and Research, National Institute of Technology of Mexico/Technological Institute of Oaxaca, Oaxaca, Mexico
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4
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The Flavone Cirsiliol from Salvia x jamensis Binds the F 1 Moiety of ATP Synthase, Modulating Free Radical Production. Cells 2022; 11:cells11193169. [PMID: 36231131 PMCID: PMC9562182 DOI: 10.3390/cells11193169] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/25/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
Several studies have shown that mammalian retinal rod outer segments (OS) are peculiar structures devoid of mitochondria, characterized by ectopic expression of the molecular machinery for oxidative phosphorylation. Such ectopic aerobic metabolism would provide the chemical energy for the phototransduction taking place in the OS. Natural polyphenols include a large variety of molecules having pleiotropic effects, ranging from anti-inflammatory to antioxidant and others. Our goal in the present study was to investigate the potential of the flavonoid cirsiliol, a trihydroxy-6,7-dimethoxyflavone extracted from Salvia x jamensis, in modulating reactive oxygen species production by the ectopic oxidative phosphorylation taking place in the OS. Our molecular docking analysis identified cirsiliol binding sites inside the F1 moiety of the nanomotor F1Fo-ATP synthase. The experimental approach was based on luminometry, spectrophotometry and cytofluorimetry to evaluate ATP synthesis, respiratory chain complex activity and H2O2 production, respectively. The results showed significant dose-dependent inhibition of ATP production by cirsiliol. Moreover, cirsiliol was effective in reducing the free radical production by the OS exposed to ambient light. We report a considerable protective effect of cirsiliol on the structural stability of rod OS, suggesting it may be considered a promising compound against oxidative stress.
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5
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Kang W, Suzuki M, Saito T, Miyado K. Emerging Role of TCA Cycle-Related Enzymes in Human Diseases. Int J Mol Sci 2021; 22:13057. [PMID: 34884868 PMCID: PMC8657694 DOI: 10.3390/ijms222313057] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/27/2021] [Accepted: 11/30/2021] [Indexed: 02/03/2023] Open
Abstract
The tricarboxylic acid (TCA) cycle is the main source of cellular energy and participates in many metabolic pathways in cells. Recent reports indicate that dysfunction of TCA cycle-related enzymes causes human diseases, such as neurometabolic disorders and tumors, have attracted increasing interest in their unexplained roles. The diseases which develop as a consequence of loss or dysfunction of TCA cycle-related enzymes are distinct, suggesting that each enzyme has a unique function. This review aims to provide a comprehensive overview of the relationship between each TCA cycle-related enzyme and human diseases. We also discuss their functions in the context of both mitochondrial and extra-mitochondrial (or cytoplasmic) enzymes.
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Affiliation(s)
- Woojin Kang
- Department of Reproductive Biology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan; (M.S.); (K.M.)
| | - Miki Suzuki
- Department of Reproductive Biology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan; (M.S.); (K.M.)
| | - Takako Saito
- Department of Applied Life Sciences, Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan;
| | - Kenji Miyado
- Department of Reproductive Biology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan; (M.S.); (K.M.)
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6
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Morelli AM, Chiantore M, Ravera S, Scholkmann F, Panfoli I. Myelin sheath and cyanobacterial thylakoids as concentric multilamellar structures with similar bioenergetic properties. Open Biol 2021; 11:210177. [PMID: 34905702 PMCID: PMC8670949 DOI: 10.1098/rsob.210177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
There is a surprisingly high morphological similarity between multilamellar concentric thylakoids in cyanobacteria and the myelin sheath that wraps the nerve axons. Thylakoids are multilamellar structures, which express photosystems I and II, cytochromes and ATP synthase necessary for the light-dependent reaction of photosynthesis. Myelin is a multilamellar structure that surrounds many axons in the nervous system and has long been believed to act simply as an insulator. However, it has been shown that myelin has a trophic role, conveying nutrients to the axons and producing ATP through oxidative phosphorylation. Therefore, it is tempting to presume that both membranous structures, although distant in the evolution tree, share not only a morphological but also a functional similarity, acting in feeding ATP synthesized by the ATP synthase to the centre of the multilamellar structure. Therefore, both molecular structures may represent a convergent evolution of life on Earth to fulfill fundamentally similar functions.
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Affiliation(s)
| | - Mariachiara Chiantore
- Department of Earth, Environment and Life Sciences, University of Genova, Genova, Italy
| | - Silvia Ravera
- Experimental Medicine Department, University of Genova, Genova, Italy
| | - Felix Scholkmann
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Isabella Panfoli
- Experimental Medicine Department, University of Genova, Genova, Italy
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7
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Ravera S, Bartolucci M, Calzia D, Morelli AM, Panfoli I. Efficient extra-mitochondrial aerobic ATP synthesis in neuronal membrane systems. J Neurosci Res 2021; 99:2250-2260. [PMID: 34085315 DOI: 10.1002/jnr.24865] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 04/29/2021] [Accepted: 05/10/2021] [Indexed: 11/09/2022]
Abstract
The nervous system displays high energy consumption, apparently not fulfilled by mitochondria, which are underrepresented therein. The oxidative phosphorylation (OxPhos) activity, a mitochondrial process that aerobically provides ATP, has also been reported also in the myelin sheath and the rod outer segment (OS) disks. Thus, commonalities and differences between the extra-mitochondrial and mitochondrial aerobic metabolism were evaluated in bovine isolated myelin (IM), rod OS, and mitochondria-enriched fractions (MIT). The subcellular fraction quality and the absence of contamination fractions have been estimated by western blot analysis. Oxygen consumption and ATP synthesis were stimulated by conventional (pyruvate + malate or succinate) and unconventional (NADH) substrates, observing that oxygen consumption and ATP synthesis by IM and rod OS are more efficient than by MIT, in the presence of both kinds of respiratory substrates. Mitochondria did not utilize NADH as a respiring substrate. When ATP synthesis by either sample was assayed in the presence of 10-100 µM ATP in the assay medium, only in IM and OS it was not inhibited, suggesting that the ATP exportation by the mitochondria is limited by extravesicular ATP concentration. Interestingly, IM and OS but not mitochondria appear able to synthesize ATP at a later time with respect to exposure to respiratory substrates, supporting the hypothesis that the proton gradient produced by the electron transport chain is buffered by membrane phospholipids. The putative transfer mode of the OxPhos molecular machinery from mitochondria to the extra-mitochondrial structures is also discussed, opening new perspectives in the field of neurophysiology.
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Affiliation(s)
- Silvia Ravera
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Martina Bartolucci
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genoa, Italy.,Department of Pharmacy, Biochemistry Lab., University of Genoa, Genoa, Italy
| | - Daniela Calzia
- Department of Pharmacy, Biochemistry Lab., University of Genoa, Genoa, Italy
| | | | - Isabella Panfoli
- Department of Pharmacy, Biochemistry Lab., University of Genoa, Genoa, Italy
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8
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Ravera S, Esposito A, Degan P, Caicci F, Manni L, Liguori A, Bisio A, Iobbi V, Schito A, Traverso CE, Panfoli I. The diterpene Manool extracted from Salvia tingitana lowers free radical production in retinal rod outer segments by inhibiting the extramitochondrial F 1 F o ATP synthase. Cell Biochem Funct 2021; 39:528-535. [PMID: 33472276 DOI: 10.1002/cbf.3618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/17/2020] [Accepted: 12/28/2020] [Indexed: 11/05/2022]
Abstract
Uncontrolled oxidative stress production, especially in the outer retina is one of the causes of retinal degenerations. Mitochondria are considered the principal source of oxidative stress. However, a Reactive Oxygen Intermediates (ROI) production in the retinal photoreceptor layer seems to depend also on the expression of an extramitochondrial oxidative phosphorylation (OxPhos) machinery in the rod outer segments (OS). In fact, OS conduct aerobic metabolism, producing ATP through oxygen consumption, although it is devoid of mitochondria. As diterpenes display an antioxidant effect, we have evaluated the effect Manool, extracted from Salvia tingitana, on the extramitochondrial OxPhos and the ROI production in the retinal rod OS. Results confirm that the OxPhos machinery is ectopically expressed in the OS and that F1 Fo -ATP synthase is a target of Manool, which inhibited the OS ATP synthesis, binding the F1 moiety with high affinity, as analysed by molecular docking. Moreover, the overall slowdown of OxPhos metabolism reduced the ROI production elicited in the OS by light exposure, in vitro. In conclusion, data are consistent with the antioxidant properties of Salvia spp., suggesting its ability to lower oxidative stress production, a primary risk factor for degenerative retinal diseases. SIGNIFICANCE OF THE STUDY: Here we show that Manool, a diterpene extracted from Salvia tingitana has the potential to lower the free radical production by light-exposed rod outer segments in vitro, by specifically targeting the rod OS F1 Fo -ATP synthase belonging to the extramitochondrial OxPhos expressed on the disk membrane. The chosen experimental model allowed to show that the rod OS is a primary producer of oxidative stress linked to the pathogenesis of degenerative retinal diseases. Data are also consistent with the antioxidant and anti-inflammatory action of Salvia spp., suggesting a beneficial effect also in vivo.
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Affiliation(s)
- Silvia Ravera
- Dipartimento di Medicina Sperimentale, Università di Genova, Genova, Italy
| | - Alfonso Esposito
- Centro di Biologia Integrata (CIBIO), Università di Trento, Trento, Italy
| | - Paolo Degan
- UOC Mutagenesi, IRCCS Policlinico San Martino -IST (Istituto Nazionale per la Ricerca sul Cancro), Genova, Italy
| | - Federico Caicci
- Dipartimento di Biologia, Università di Padova, Padova, Italy
| | - Lucia Manni
- Dipartimento di Biologia, Università di Padova, Padova, Italy
| | - Anna Liguori
- Dipartimento di Farmacia (DIFAR), Università di Genova, Genova, Italy
| | - Angela Bisio
- Dipartimento di Farmacia (DIFAR), Università di Genova, Genova, Italy
| | - Valeria Iobbi
- Dipartimento di Farmacia (DIFAR), Università di Genova, Genova, Italy
| | - Anna Schito
- Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Università di Genova, Genova, Italy
| | | | - Isabella Panfoli
- Dipartimento di Farmacia (DIFAR), Università di Genova, Genova, Italy
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9
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Bruschi M, Bartolucci M, Petretto A, Calzia D, Caicci F, Manni L, Traverso CE, Candiano G, Panfoli I. Differential expression of the five redox complexes in the retinal mitochondria or rod outer segment disks is consistent with their different functionality. FASEB Bioadv 2020; 2:315-324. [PMID: 32395704 PMCID: PMC7211042 DOI: 10.1096/fba.2019-00093] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 11/27/2019] [Accepted: 03/05/2020] [Indexed: 12/28/2022] Open
Abstract
PURPOSE The retinal rod outer segment (OS) disk membranes, devoid of mitochondria, conducts oxidative phosphorylation (OxPhos). This study aimed at identifying which proteins expressed in the retinal rod OS disks determined the considerable adenosine-5'-triphosphate production and oxygen consumption observed in comparison with retinal mitochondria. PROCEDURES Characterization was conducted by immunogold transmission electron microscopy on retinal sections. OxPhos was studied by oximetry and luminometry. The proteomes of OS disks and mitochondria purified from bovine retinas were studied by mass spectrometry. Statistical and bioinformatic analyses were conducted by univariate, multivariate, and machine learning methods. RESULTS Weighted gene coexpression network analysis identified two protein expression profile modules functionally associated with either retinal mitochondria or disk samples, in function of a strikingly different ability of each sample to utilized diverse substrate for F1Fo-ATP synthase. The OS disk proteins correlated better than mitochondria with the tricarboxylic acids cycle and OxPhos proteins. CONCLUSIONS The differential enrichment of the expression profile of the OxPhos proteins in the disks versus mitochondria suggests that these proteins may represent a true proteome component of the former, with different functionality. These findings may shed new light on the pathogenesis of rod-driven retinal degenerative diseases.
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Affiliation(s)
- Maurizio Bruschi
- Laboratory of Molecular NephrologyIstituto Giannina GasliniGenoaItaly
| | - Martina Bartolucci
- Laboratory of Mass Spectrometry‐Core FacilitiesIstituto Giannina GasliniGenovaItaly
| | - Andrea Petretto
- Laboratory of Mass Spectrometry‐Core FacilitiesIstituto Giannina GasliniGenovaItaly
| | - Daniela Calzia
- Dipartimento di Farmacia‐DIFARUniversità di GenovaGenoaItaly
| | | | - Lucia Manni
- Department of BiologyUniversità di PadovaPadovaItaly
| | - Carlo Enrico Traverso
- Clinica Oculistica, (Di.N.O.G.M.I.) Università Department of Intensive Care di GenovaIRCCS Azienda Ospedaliera Universitaria San Martino‐ISTGenoaItaly
| | - Giovanni Candiano
- Laboratory of Molecular NephrologyIstituto Giannina GasliniGenoaItaly
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10
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Bisio A, Schito AM, Pedrelli F, Danton O, Reinhardt JK, Poli G, Tuccinardi T, Bürgi T, De Riccardis F, Giacomini M, Calzia D, Panfoli I, Schito GC, Hamburger M, De Tommasi N. Antibacterial and ATP Synthesis Modulating Compounds from Salvia tingitana. JOURNAL OF NATURAL PRODUCTS 2020; 83:1027-1042. [PMID: 32182064 PMCID: PMC7997632 DOI: 10.1021/acs.jnatprod.9b01024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Indexed: 05/05/2023]
Abstract
A surface extract of the aerial parts of Salvia tingitana afforded a nor-sesterterpenoid (1) and eight new sesterterpenoids (2-̵9), along with five known sesterterpenoids, five labdane and one abietane diterpenoid, one sesquiterpenoid, and four flavonoids. The structures of the new compounds were established by 1D and 2D NMR spectroscopy, HRESIMS, and VCD data and Mosher's esters analysis. The antimicrobial activity of compounds was evaluated against 30 human pathogens including 27 clinical strains and three isolates of marine origin for their possible implications on human health. The methyl ester of salvileucolide (10), salvileucolide-6,23-lactone (11), sclareol (15), and manool (17) were the most active against Gram-positive bacteria. The compounds were also tested for the inhibition of ATP production in purified mammalian rod outer segments. Terpenoids 10, 11, 15, and 17 inhibited ATP production, while only 17 inhibited also ATP hydrolysis. Molecular modeling studies confirmed the capacity of 17 to interact with mammalian ATP synthase. A significant reduction of ATP production in the presence of 17 was observed in Enterococcus faecalis and E. faecium isolates.
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Affiliation(s)
- Angela Bisio
- Department
of Pharmacy, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Anna M. Schito
- Department
of Integrated Surgical and Diagnostical Sciences, University of Genova, Largo Rosanna Benzi 8, 16145 Genova, Italy
| | - Francesca Pedrelli
- Department
of Pharmacy, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Ombeline Danton
- Department
of Pharmaceutical Sciences, University of
Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Jakob K. Reinhardt
- Department
of Pharmaceutical Sciences, University of
Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Giulio Poli
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Tiziano Tuccinardi
- Department
of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Thomas Bürgi
- Department
of Chemical Physics, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Genève 4, Switzerland
| | - Francesco De Riccardis
- Department
of Chemistry and Biology, University of
Salerno, Via Giovanni Paolo II 132, 84084 Salerno, Italy
| | - Mauro Giacomini
- Department
of Informatics Bioengineering Robotics and System Engineering, University of Genova, Via all’Opera Pia, 13, 16145 Genova, Italy
| | - Daniela Calzia
- Department
of Pharmacy, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Isabella Panfoli
- Department
of Pharmacy, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Gian Carlo Schito
- Department
of Pharmacy, University of Genova, Viale Cembrano 4, 16148 Genova, Italy
| | - Matthias Hamburger
- Department
of Pharmaceutical Sciences, University of
Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Nunziatina De Tommasi
- Department
of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Salerno, Italy
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11
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Sinha T, Ikelle L, Naash MI, Al-Ubaidi MR. The Intersection of Serine Metabolism and Cellular Dysfunction in Retinal Degeneration. Cells 2020; 9:cells9030674. [PMID: 32164325 PMCID: PMC7140600 DOI: 10.3390/cells9030674] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 12/14/2022] Open
Abstract
In the past, the importance of serine to pathologic or physiologic anomalies was inadequately addressed. Omics research has significantly advanced in the last two decades, and metabolomic data of various tissues has finally brought serine metabolism to the forefront of metabolic research, primarily for its varied role throughout the central nervous system. The retina is one of the most complex neuronal tissues with a multitude of functions. Although recent studies have highlighted the importance of free serine and its derivatives to retinal homeostasis, currently few reviews exist that comprehensively analyze the topic. Here, we address this gap by emphasizing how and why the de novo production and demand for serine is exceptionally elevated in the retina. Many basic physiological functions of the retina require serine. Serine-derived sphingolipids and phosphatidylserine for phagocytosis by the retinal pigment epithelium (RPE) and neuronal crosstalk of the inner retina via D-serine require proper serine metabolism. Moreover, serine is involved in sphingolipid–ceramide balance for both the outer retina and the RPE and the reductive currency generation for the RPE via serine biosynthesis. Finally and perhaps the most vital part of serine metabolism is free radical scavenging in the entire retina via serine-derived scavengers like glycine and GSH. It is hard to imagine that a single tissue could have such a broad and extensive dependency on serine homeostasis. Any dysregulation in serine mechanisms can result in a wide spectrum of retinopathies. Therefore, most critically, this review provides a strong argument for the exploration of serine-based clinical interventions for retinal pathologies.
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Affiliation(s)
| | | | - Muna I. Naash
- Correspondence: (M.I.N.); (M.R.A.-U.); Tel.: +1-713-743-1651 (M.I.N.); Fax: +1-713-743-0226 (M.I.N.)
| | - Muayyad R. Al-Ubaidi
- Correspondence: (M.I.N.); (M.R.A.-U.); Tel.: +1-713-743-1651 (M.I.N.); Fax: +1-713-743-0226 (M.I.N.)
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12
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Elmi A, Ventrella D, Laghi L, Carnevali G, Zhu C, Pertile G, Barone F, Benfenati F, Bacci ML. 1H NMR Spectroscopy Characterization of Porcine Vitreous Humor in Physiological and Photoreceptor Degeneration Conditions. ACTA ACUST UNITED AC 2019; 60:741-747. [DOI: 10.1167/iovs.18-25675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Alberto Elmi
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Domenico Ventrella
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Luca Laghi
- Centre of Foodomics, Department of Agro-Food Science and Technology, University of Bologna, Bologna, Italy
| | - Giacomo Carnevali
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Chenglin Zhu
- Centre of Foodomics, Department of Agro-Food Science and Technology, University of Bologna, Bologna, Italy
| | - Grazia Pertile
- Ophthalmology Department, Sacro Cuore Hospital - Don Calabria, Negrar, Italy
| | - Francesca Barone
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
- Ophthalmology Department, Sacro Cuore Hospital - Don Calabria, Negrar, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Maria Laura Bacci
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
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13
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Ravera S, Signorello MG, Bartolucci M, Ferrando S, Manni L, Caicci F, Calzia D, Panfoli I, Morelli A, Leoncini G. Extramitochondrial energy production in platelets. Biol Cell 2018. [PMID: 29537672 DOI: 10.1111/boc.201700025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND INFORMATION Energy demand in human platelets is very high, to carry out their functions. As for most human cells, the aerobic metabolism represents the primary energy source in platelets, even though mitochondria are negligibly represented. Following the hypothesis that other structures could be involved in chemical energy production, in this work, we have investigated the functional expression of an extramitochondrial aerobic metabolism in platelets. RESULTS Oximetric and luminometric analyses showed that platelets consume large amounts of oxygen and produce ATP in the presence of common respiring substrates, such as pyruvate + malate or succinate, although morphological electron microscopy analysis showed that these contain few mitochondria. However, evaluation of the anaerobic glycolytic metabolism showed that only 13% of consumed glucose was converted to lactate. Interestingly, the highest OXPHOS activity was observed in the presence of NADH, not a readily permeant respiring substrate for mitochondria. Also, oxygen consumption and ATP synthesis fuelled by NADH were not affected by atractyloside, an inhibitor of the adenine nucleotide translocase, suggesting that these processes may not be ascribed to mitochondria. Functional data were confirmed by immunofluorescence microscopy and Western blot analyses, showing a consistent expression of the β subunit of F1 Fo -ATP synthase and COXII, a subunit of Complex IV, but a low signal of translocase of the inner mitochondrial membrane (a protein not involved in OXPHOS metabolism). Interestingly, the NADH-stimulated oxygen consumption and ATP synthesis increased in the presence of the physiological platelets agonists, thrombin or collagen. CONCLUSIONS Data suggest that in platelets, aerobic energy production is mainly driven by an extramitochondrial OXPHOS machinery, originated inside the megakaryocyte, and that this metabolism plays a pivotal role in platelet activation. SIGNIFICANCE This work represents a further example of the existence of an extramitochondrial aerobic metabolism, which can contribute to the cellular energy balance.
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Affiliation(s)
- Silvia Ravera
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
| | | | - Martina Bartolucci
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
| | - Sara Ferrando
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), University of Genoa, Genoa, 16132, Italy
| | - Lucia Manni
- Department of Biology, Università di Padova, Padova, Italy
| | | | - Daniela Calzia
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
| | - Isabella Panfoli
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
| | - Alessandro Morelli
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
| | - Giuliana Leoncini
- Department of Pharmacy, Biochemistry Lab, University of Genova, Genova, 16132, Italy
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Calzia D, Garbarino G, Caicci F, Pestarino M, Manni L, Traverso CE, Panfoli I, Candiani S. Evidence of Oxidative Phosphorylation in Zebrafish Photoreceptor Outer Segments at Different Larval Stages. J Histochem Cytochem 2018; 66:497-509. [PMID: 29547350 DOI: 10.1369/0022155418762389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Previous studies on purified bovine rod outer segments (OS) disks pointed to Oxidative Phosphorylation (OXPHOS) as being the most likely mechanism involved in ATP production, as yet not fully understood, to support the first phototransduction steps. Bovine and murine rod OS disks, devoid of mitochondria, would house respiratory chain complexes I to IV and ATP synthase, similar to mitochondria. Zebrafish ( Danio rerio) is a well-suited animal model to study vertebrate embryogenesis as well as the retina, morphologically and functionally similar to its human counterpart. The present article reports fluorescence and Transmission Electron Microscopy colocalization analyses of respiratory complexes I and IV and ATP synthase with zpr3, the rod OS marker, in adult and larval zebrafish retinas. MitoTracker Deep Red 633 staining and assays of complexes I and III-IV activity suggest that those proteins are active in OS. Results show that an extramitochondrial aerobic metabolism is active in the zebrafish OS at 4 and 10 days of larval development, as well as in adults, suggesting that it is probably maintained during embryogenesis. Data support the hypothesis of an extramitochondrial aerobic metabolism in the OS of zebrafish.
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Affiliation(s)
- Daniela Calzia
- Department of Pharmacy-DIFAR-Biochemistry and Physiology Lab, University of Genoa, Genova, Italy
| | - Greta Garbarino
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), University of Genoa, Genova, Italy
| | | | - Mario Pestarino
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), University of Genoa, Genova, Italy
| | - Lucia Manni
- Department of Biology, Università di Padova, Padova, Italy
| | - Carlo Enrico Traverso
- Clinica Oculistica, (Di.N.O.G.M.I.), University of Genoa, IRCCS Azienda Ospedaliera Universitaria San Martino-IST, Genova, Italy
| | - Isabella Panfoli
- Department of Pharmacy-DIFAR-Biochemistry and Physiology Lab, University of Genoa, Genova, Italy
| | - Simona Candiani
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), University of Genoa, Genova, Italy
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Bruschi M, Santucci L, Ravera S, Bartolucci M, Petretto A, Calzia D, Ghiggeri GM, Ramenghi LA, Candiano G, Panfoli I. Metabolic Signature of Microvesicles from Umbilical Cord Mesenchymal Stem Cells of Preterm and Term Infants. Proteomics Clin Appl 2017; 12:e1700082. [DOI: 10.1002/prca.201700082] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 10/23/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Maurizio Bruschi
- Laboratory of Molecular Nephrology Istituto Giannina Gaslini; Genoa Italy
| | - Laura Santucci
- Laboratory of Molecular Nephrology Istituto Giannina Gaslini; Genoa Italy
| | - Silvia Ravera
- Dipartimento di Farmacia; Laboratorio di Biochimica; Università di Genova; Genoa Italy
| | - Martina Bartolucci
- Laboratory of Mass Spectrometry - Core Facilities; Istituto Giannina Gaslini; Genova Italy
| | - Andrea Petretto
- Laboratory of Mass Spectrometry - Core Facilities; Istituto Giannina Gaslini; Genova Italy
| | - Daniela Calzia
- Dipartimento di Farmacia; Laboratorio di Biochimica; Università di Genova; Genoa Italy
| | | | - Luca A. Ramenghi
- Neonatal Intensive Care Unit; Istituto Giannina Gaslini; Genoa Italy
| | - Giovanni Candiano
- Laboratory of Molecular Nephrology Istituto Giannina Gaslini; Genoa Italy
| | - Isabella Panfoli
- Dipartimento di Farmacia; Laboratorio di Biochimica; Università di Genova; Genoa Italy
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Bridges between mitochondrial oxidative stress, ER stress and mTOR signaling in pancreatic β cells. Cell Signal 2016; 28:1099-104. [DOI: 10.1016/j.cellsig.2016.05.007] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/05/2016] [Accepted: 05/06/2016] [Indexed: 02/06/2023]
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17
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Bruschi M, Santucci L, Ravera S, Candiano G, Bartolucci M, Calzia D, Lavarello C, Inglese E, Ramenghi LA, Petretto A, Ghiggeri GM, Panfoli I. Human urinary exosome proteome unveils its aerobic respiratory ability. J Proteomics 2016; 136:25-34. [PMID: 26850698 DOI: 10.1016/j.jprot.2016.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 12/13/2022]
Abstract
UNLABELLED Exosomes are 40-100-nm vesicles released by most cell types after fusion of multivesicular endosomes with the plasma membrane. Exosomes, ubiquitary in body fluids including urines, contain proteins and RNA species specific of the tissue of origin. Exosomes from urine have been extensively studied as a promising reservoir for disease biomarkers. Here, we report the proteome analysis of urinary exosomes compared to urinoma, studied by Orbitrap mass spectrometry. A discovery approach was utilized on the sample. 3429 proteins were present, with minimal overlapping among exosome and urinoma. 959 proteins (28%) in exosome and 1478 proteins (43%) in urinoma were exclusively present in only one group. By cytoscape analysis, the biological process gene ontology was correlated to their probability (P ≤ 0.05) to be functional. This was never studied before and showed a significant clustering around metabolic functions, in particular to aerobic ATP production. Urinary exosomes carry out oxidative phosphorylation, being able to synthesize ATP and consume oxygen. A previously unsuspected function emerges for human urinary exosomes as bioactive vesicles that consume oxygen to aerobically synthesize ATP. Determination of normal human urine proteome can help generate the healthy urinary protein database for comparison, useful for various renal diseases. BIOLOGICAL SIGNIFICANCE The findings reported represent a significant advance in the understanding of the healthy human urinary proteome. The methodology utilized to analyze the collection of proteomic data allowed the assessment of the unique composition of urinary exosomes with respect to urinoma and to elucidate the presence in the former of molecular pathways previously unknown. The paper has the potential to impact its field of research, due to the biological relevance of the metabolic capacity of urinary exosomes, which may represent their important general feature.
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Affiliation(s)
- Maurizio Bruschi
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Laura Santucci
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Silvia Ravera
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy
| | - Giovanni Candiano
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Martina Bartolucci
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Daniela Calzia
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy
| | - Chiara Lavarello
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Elvira Inglese
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Luca A Ramenghi
- Neonatal Intensive Care Unit, Istituto Giannina Gaslini, Genoa, Italy
| | - Andrea Petretto
- Laboratory of Mass Spectrometry - Core Facilities, Istituto Giannina Gaslini, Genova, Italy
| | - Gian Marco Ghiggeri
- Division of Nephrology, Dialysis, and Transplantation and Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | - Isabella Panfoli
- Dipartimento di Farmacia, Laboratorio di Biochimica, Università di Genova, Genoa, Italy.
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Bruschi M, Ravera S, Santucci L, Candiano G, Bartolucci M, Calzia D, Lavarello C, Inglese E, Petretto A, Ghiggeri G, Panfoli I. The human urinary exosome as a potential metabolic effector cargo. Expert Rev Proteomics 2015; 12:425-32. [DOI: 10.1586/14789450.2015.1055324] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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19
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Gibson GE, Xu H, Chen HL, Chen W, Denton TT, Zhang S. Alpha-ketoglutarate dehydrogenase complex-dependent succinylation of proteins in neurons and neuronal cell lines. J Neurochem 2015; 134:86-96. [PMID: 25772995 DOI: 10.1111/jnc.13096] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/13/2015] [Accepted: 03/04/2015] [Indexed: 01/13/2023]
Abstract
Reversible post-translation modifications of proteins are common in all cells and appear to regulate many processes. Nevertheless, the enzyme(s) responsible for the alterations and the significance of the modification are largely unknown. Succinylation of proteins occurs and causes large changes in the structure of proteins; however, the source of the succinyl groups, the targets, and the consequences of these modifications on other proteins remain unknown. These studies focused on succinylation of mitochondrial proteins. The results demonstrate that the α-ketoglutarate dehydrogenase complex (KGDHC) can serve as a trans-succinylase that mediates succinylation in an α-ketoglutarate-dependent manner. Inhibition of KGDHC reduced succinylation of both cytosolic and mitochondrial proteins in cultured neurons and in a neuronal cell line. Purified KGDHC can succinylate multiple proteins including other enzymes of the tricarboxylic acid cycle leading to modification of their activity. Inhibition of KGDHC also modifies acetylation by modifying the pyruvate dehydrogenase complex. The much greater effectiveness of KGDHC than succinyl-CoA suggests that the catalysis owing to the E2k succinyltransferase is important. Succinylation appears to be a major signaling system and it can be mediated by KGDHC. Reversible post-translation modifications of proteins are common and may regulate many processes. Succinylation of proteins occurs and causes large changes in the structure of proteins. However, the source of the succinyl groups, the targets, and the consequences of these modifications on other proteins remains unknown. The results demonstrate that the mitochondrial α-ketoglutarate dehydrogenase complex (KGDHC) can succinylate multiple mitochondrial proteins and alter their function. Succinylation appears to be a major signaling system and it can be mediated by KGDHC.
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Affiliation(s)
- Gary E Gibson
- Brain and Mind Research Institute, Weill Cornell Medical College, Burke Medical Research Institute, White Plains, New York, USA
| | - Hui Xu
- Brain and Mind Research Institute, Weill Cornell Medical College, Burke Medical Research Institute, White Plains, New York, USA
| | - Huan-Lian Chen
- Brain and Mind Research Institute, Weill Cornell Medical College, Burke Medical Research Institute, White Plains, New York, USA
| | - Wei Chen
- Proteomics and Mass Spectrometry Facility, Institute of Biotechnology, Cornell University, Ithaca, New York, USA
| | - Travis T Denton
- College of Pharmacy, Washington State University, Spokane, Washington, USA
| | - Sheng Zhang
- Proteomics and Mass Spectrometry Facility, Institute of Biotechnology, Cornell University, Ithaca, New York, USA
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20
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Calzia D, Garbarino G, Caicci F, Manni L, Candiani S, Ravera S, Morelli A, Traverso CE, Panfoli I. Functional expression of electron transport chain complexes in mouse rod outer segments. Biochimie 2014; 102:78-82. [PMID: 24565809 DOI: 10.1016/j.biochi.2014.02.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 02/14/2014] [Indexed: 10/25/2022]
Abstract
Rod photoreceptors efficiently carry out phototransduction cascade, an energetically costly process. Our recent data in bovine rod outer segment (OS) demonstrated that ATP for phototransduction is produced by an extramitochondrial oxidative phosphorylation, thanks to the expression of the Electron Transport Chain (ETC) complexes and of F1Fo ATP synthase in disks. Here we have focused on mouse retinas, reporting the activity of ETC complexes I, II, IV assayed directly on unfixed mouse eye sections, as well as immunogold TEM analysis of fixed mouse eye sections to verify the presence of ND4L subunit of ETC complex I and subunit IV of ETC complex IV in rod OS. Data suggest the presence of functional ETC in mouse rod OS, like their bovine counterpart. The protocol here developed for in situ assay of the ETC complexes activity represents a reliable method for the detection of ETC dysfunction in mice models of retinal pathologies. In fact, the ETC is a major source of reactive oxygen intermediates, and oxidative stress, especially when ectopically expressed in the OS. In turn, oxidative stress contributes to many retinal pathologies, such as diabetic retinopathy, age related macular degeneration, photoreceptor death after retinal detachment and some forms of retinitis pigmentosa.
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Affiliation(s)
- Daniela Calzia
- Department of Pharmacy, DIFAR-Biochemistry Lab, University of Genova, Italy.
| | | | | | - Lucia Manni
- Department of Biology, Università di Padova, Italy
| | | | - Silvia Ravera
- Department of Pharmacy, DIFAR-Biochemistry Lab, University of Genova, Italy
| | - Alessandro Morelli
- Department of Pharmacy, DIFAR-Biochemistry Lab, University of Genova, Italy
| | | | - Isabella Panfoli
- Department of Pharmacy, DIFAR-Biochemistry Lab, University of Genova, Italy
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Antioxidant drug therapy approaches for neuroprotection in chronic diseases of the retina. Int J Mol Sci 2014; 15:1865-86. [PMID: 24473138 PMCID: PMC3958826 DOI: 10.3390/ijms15021865] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 01/18/2014] [Accepted: 01/21/2014] [Indexed: 12/31/2022] Open
Abstract
The molecular pathways contributing to visual signal transduction in the retina generate a high energy demand that has functional and structural consequences such as vascularization and high metabolic rates contributing to oxidative stress. Multiple signaling cascades are involved to actively regulate the redox state of the retina. Age-related processes increase the oxidative load, resulting in chronically elevated levels of oxidative stress and reactive oxygen species, which in the retina ultimately result in pathologies such as glaucoma or age-related macular degeneration, as well as the neuropathic complications of diabetes in the eye. Specifically, oxidative stress results in deleterious changes to the retina through dysregulation of its intracellular physiology, ultimately leading to neurodegenerative and potentially also vascular dysfunction. Herein we will review the evidence for oxidative stress-induced contributions to each of the three major ocular pathologies, glaucoma, age-related macular degeneration, and diabetic retinopathy. The premise for neuroprotective strategies for these ocular disorders will be discussed in the context of recent clinical and preclinical research pursuing novel therapy development approaches.
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22
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Tricarboxylic acid cycle-sustained oxidative phosphorylation in isolated myelin vesicles. Biochimie 2013; 95:1991-8. [DOI: 10.1016/j.biochi.2013.07.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/02/2013] [Indexed: 12/11/2022]
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23
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Calzia D, Barabino S, Bianchini P, Garbarino G, Oneto M, Caicci F, Diaspro A, Tacchetti C, Manni L, Candiani S, Ravera S, Morelli A, Enrico Traverso C, Panfoli I. New findings in ATP supply in rod outer segments: insights for retinopathies. Biol Cell 2013; 105:345-58. [PMID: 23659850 DOI: 10.1111/boc.201300003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 05/03/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND INFORMATION The rod outer segment (OS) is the specialised organelle where phototransduction takes place. Our previous proteomic and biochemical analyses on purified rod disks showed the functional expression of the respiratory chain complexes I-IV and F1 Fo -ATP synthase in OS disks, as well as active soluble tricarboxylic acid cycle enzymes. Here, we focussed our study on the whole OS that contains the cytosol and plasma membrane and disks as native flattened saccules, unlike spherical osmotically intact disks. RESULTS OS were purified from bovine retinas and characterised for purity. Oximetry, ATP synthesis and cytochrome c oxidase (COX) assays were performed. The presence of COX and F₁F₀-ATP synthase (ATP synthase) was assessed by semi-quantitative Western blotting, immunofluorescence or confocal laser scanning microscopy on whole bovine retinas and bovine retinal sections and by immunogold transmission electron microscopy (TEM) of purified OS or bovine retinal sections. Both ATP synthase and COX are catalytically active in OS. These are able to consume oxygen (O₂) in the presence of pyruvate and malate. CLSM analyses showed that rhodopsin autofluorescence and MitoTracker Deep Red 633 fluorescence co-localise on rod OS. Data are confirmed by co-localisation studies of ATP synthase with Rh in rod OS by immunofluorescence and TEM in bovine retinal sections. CONCLUSIONS Our data confirm the expression and activity of COX and ATP synthase in OS, suggestive of the presence of an extra-mitochondrial oxidative phosphorylation in rod OS, meant to supply ATP for the visual transduction. In this respect, the membrane rich OS environment would be meant to absorb both light and O₂. The ability of OS to manipulate O₂ may shed light on the pathogenesis of many retinal degenerative diseases ascribed to oxidative stress, as well as on the efficacy of the treatment with dietary supplements, presently utilised as supporting therapies.
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Affiliation(s)
- Daniela Calzia
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Lab, University of Genoa, Genova, Italy
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Abstract
The lens and retina of the human eye are exposed constantly to light and oxygen. In situ phototransduction and oxidative phosphorylation within photoreceptors produces a high level of phototoxic and oxidative related stress. Within the eye, the carotenoids lutein and zeaxanthin are present in high concentrations in contrast to other human tissues. We discuss the role of lutein and zeaxanthin in ameliorating light and oxygen damage, and preventing age-related cellular and tissue deterioration in the eye. Epidemiologic research shows an inverse association between levels of lutein and zeaxanthin in eye tissues and age related degenerative diseases such as macular degeneration (AMD) and cataracts. We examine the role of these carotenoids as blockers of blue-light damage and quenchers of oxygen free radicals. This article provides a review of possible mechanisms of lutein action at a cellular and molecular level. Our review offers insight into current clinical trials and experimental animal studies involving lutein, and possible role of nutritional intervention in common ocular diseases that cause blindness.
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Ravera S, Nobbio L, Visigalli D, Bartolucci M, Calzia D, Fiorese F, Mancardi G, Schenone A, Morelli A, Panfoli I. Oxydative phosphorylation in sciatic nerve myelin and its impairment in a model of dysmyelinating peripheral neuropathy. J Neurochem 2013; 126:82-92. [PMID: 23578247 DOI: 10.1111/jnc.12253] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/13/2013] [Accepted: 03/14/2013] [Indexed: 11/30/2022]
Abstract
Myelin sheath is the proteolipid membrane wrapping the axons of CNS and PNS. We have shown data suggesting that CNS myelin conducts oxidative phosphorylation (OXPHOS), challenging its role in limiting the axonal energy expenditure. Here, we focused on PNS myelin. Samples were: (i) isolated myelin vesicles (IMV) from sciatic nerves, (ii) mitochondria from primary Schwann cell cultures, and (iii) sciatic nerve sections, from wild type or Charcot-Marie-Tooth type 1A (CMT1A) rats. The latter used as a model of dys-demyelination. O₂ consumption and activity of OXPHOS proteins from wild type (Wt) or CMT1A sciatic nerves showed some differences. In particular, O₂ consumption by IMV from Wt and CMT1A 1-month-old rats was comparable, while it was severely impaired in IMV from adult affected animals. Mitochondria extracted from CMT1A Schwann cell did not show any dysfunction. Transmission electron microscopy studies demonstrated an increased mitochondrial density in dys-demyelinated axons, as to compensate for the loss of respiration by myelin. Confocal immunohistochemistry showed the expression of OXPHOS proteins in the myelin sheath, both in Wt and dys-demyelinated nerves. These revealed an abnormal morphology. Taken together these results support the idea that also PNS myelin conducts OXPHOS to sustain axonal function.
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Are rod outer segment ATP-ase and ATP-synthase activity expression of the same protein? Cell Mol Neurobiol 2013; 33:637-49. [PMID: 23568658 DOI: 10.1007/s10571-013-9926-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 03/12/2013] [Indexed: 12/15/2022]
Abstract
Vertebrate retinal rod outer segments (OS) consist of a stack of disks surrounded by the plasma membrane, where phototransduction takes place. Energetic metabolism in rod OS remains obscure. Literature described a so-called Mg(2+)-dependent ATPase activity, while our previous results demonstrated the presence of oxidative phosphorylation (OXPHOS) in OS, sustained by an ATP synthetic activity. Here we propose that the OS ATPase and ATP synthase are the expression of the same protein, i.e., of F1Fo-ATP synthase. Imaging on bovine retinal sections showed that some OXPHOS proteins are expressed in the OS. Biochemical data on bovine purified rod OS, characterized for purity, show an ATP synthase activity, inhibited by classical F1Fo-ATP synthase inhibitors. Moreover, OS possess a pH-dependent ATP hydrolysis, inhibited by pH values below 7, suggestive of the functioning of the inhibitor of F1 (IF1) protein. WB confirmed the presence of IF1 in OS, substantiating the expression of F1Fo ATP synthase in OS. Data suggest that the OS F1Fo ATP synthase is able to hydrolyze or synthesize ATP, depending on in vitro or in vivo conditions and that the role of IF1 would be pivotal in the prevention of the reversal of ATP synthase in OS, for example during hypoxia, granting photoreceptor survival.
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Panfoli I, Calzia D, Bruschi M, Oneto M, Bianchini P, Ravera S, Petretto A, Diaspro A, Candiano G. Functional expression of oxidative phosphorylation proteins in the rod outer segment disc. Cell Biochem Funct 2013; 31:532-8. [PMID: 23322616 DOI: 10.1002/cbf.2943] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/06/2012] [Accepted: 11/28/2012] [Indexed: 11/09/2022]
Abstract
The rod Outer Segment (OS) disc, an organelle devoid of mitochondria, is specialized in phototransduction, a process requiring a continual chemical energy supply. We have shown that OS discs express functional mitochondrial electron transport chains, Fo F1 -ATP synthase and the tricarboxylic acid cycle enzymes, all mitochondrial features. Here, we focus on oxygen consumption and adenosine triphosphate (ATP) synthesis by OS discs analysing electron transport chain I-III-IV and II-II-IV pathways, supported by reduced nicotinamide adenine dinucleotide and succinate, respectively. Interestingly, respiratory capacity of discs was measurable also in the presence of 3-hydroxy-butyrrate, a typical metabolic substrate for the brain. Data were supported by a two-dimensional electrophoresis analyses conducted as our previous one, but focused to those mitochondrial proteins that are involved in oxidative phosphorylation. Carbonic anhydrase was also found active in OS discs. Moreover, colocalization of Rhodopsin with respiratory complex I and ATP synthase seems a further step in the characterization of some proteins typical of the mitochondrial inner membranes that are expressed in the rod discs. The existence of oxygen utilization in the outer retina, likely supplying ATP for phototransduction, may shed light on some retinal pathologies related to oxidative stress of the outer retina.
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Affiliation(s)
- Isabella Panfoli
- DIFAR-Biochemistry Lab., University of Genoa, 16132 Genova, Italy.
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Panfoli I, Calzia D, Ravera S, Morelli AM, Traverso CE. Extra-mitochondrial aerobic metabolism in retinal rod outer segments: new perspectives in retinopathies. Med Hypotheses 2012; 78:423-7. [PMID: 22284635 DOI: 10.1016/j.mehy.2011.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 12/06/2011] [Accepted: 12/29/2011] [Indexed: 01/11/2023]
Abstract
Vertebrate retinal rods are photoreceptors for dim-light vision. They display extreme sensitivity to light thanks to a specialized subcellular organelle, the rod outer segment. This is filled with a stack of membranous disks, expressing the proteins involved in visual transduction, a very energy demanding process. Our previous proteomic and biochemical studies have shed new light on the chemical energy processes that supply ATP to the outer segment, suggesting the presence of an extra-mitochondrial aerobic metabolism in rod outer segment, devoid of mitochondria, which would account for a quantitatively adequate ATP supply for phototransduction. Here the functional presence of an oxidative phosphorylation in the rod outer limb is examined for its relationship to many physiological and pathological data on the rod outer segment. We hypothesize that the rod outer limb is at risk of oxidative stress, in any case of impairment in the respiratory chain functioning, or of blood supply. In fact, the electron transfer chain is a major source of reactive O(2) species, known to produce severe alteration to the membrane lipids, especially those of the outer segment that are rich in polyunsaturated fatty acids. We propose that the disk membrane may become the target of reactive oxygen species that may be released by the electron transport chain under pathologic conditions. For example, during aging reactive oxygen species production increases, while cellular antioxidant capacity decreases. Also the apoptosis of the rod observed after exposure to bright or continuous illumination can be explained considering that an overfunctioning of phototransduction may damage the disk membrane to a point at which cytochrome c escapes from the intradiskal space, where it is presently supposed to be, activating a putative caspase 9 and the apoptosome. A pathogenic mechanism for many inherited and acquired retinal degenerations, representing a major problem in clinical ophthalmology, is proposed: a number of rod pathologies would be promoted by impairment of energy supply and/or oxidative stress in the rod outer segment. In conclusion we suppose that the damaging role of oxygen, be it hypoxia or hyperoxia invoked in most of the blinding diseases, acquired and even hereditary is to be seeked for inside the photoreceptor outer segment that would conceal a potential for cell death that is still to be recognized.
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Affiliation(s)
- I Panfoli
- DIPTERIS - University of Genova, Corso Europa 26, 16132 Genova, Italy.
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