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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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2
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Okolo CA, Kounatidis I, Groen J, Nahas KL, Balint S, Fish TM, Koronfel MA, Cortajarena AL, Dobbie IM, Pereiro E, Harkiolaki M. Sample preparation strategies for efficient correlation of 3D SIM and soft X-ray tomography data at cryogenic temperatures. Nat Protoc 2021; 16:2851-2885. [PMID: 33990802 DOI: 10.1038/s41596-021-00522-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 02/09/2021] [Indexed: 02/07/2023]
Abstract
3D correlative microscopy methods have revolutionized biomedical research, allowing the acquisition of multidimensional information to gain an in-depth understanding of biological systems. With the advent of relevant cryo-preservation methods, correlative imaging of cryogenically preserved samples has led to nanometer resolution imaging (2-50 nm) under harsh imaging regimes such as electron and soft X-ray tomography. These methods have now been combined with conventional and super-resolution fluorescence imaging at cryogenic temperatures to augment information content from a given sample, resulting in the immediate requirement for protocols that facilitate hassle-free, unambiguous cross-correlation between microscopes. We present here sample preparation strategies and a direct comparison of different working fiducialization regimes that facilitate 3D correlation of cryo-structured illumination microscopy and cryo-soft X-ray tomography. Our protocol has been tested at two synchrotron beamlines (B24 at Diamond Light Source in the UK and BL09 Mistral at ALBA in Spain) and has led to the development of a decision aid that facilitates experimental design with the strategic use of markers based on project requirements. This protocol takes between 1.5 h and 3.5 d to complete, depending on the cell populations used (adherent cells may require several days to grow on sample carriers).
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Affiliation(s)
- Chidinma A Okolo
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Ilias Kounatidis
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | | | - Kamal L Nahas
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK.,Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK
| | - Stefan Balint
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK
| | - Thomas M Fish
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Mohamed A Koronfel
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Aitziber L Cortajarena
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Donostia San Sebastián, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Ian M Dobbie
- Micron Advanced Imaging Consortium, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Eva Pereiro
- Beamline 09-MISTRAL, ALBA Synchrotron, Barcelona, Spain
| | - Maria Harkiolaki
- Beamline B24, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK.
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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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Ravera S, Esposito A, Degan P, Caicci F, Calzia D, Perrotta E, Manni L, Bisio A, Iobbi V, Schito A, Traverso CE, Panfoli I. Sclareol modulates free radical production in the retinal rod outer segment by inhibiting the ectopic f 1f o-atp synthase. Free Radic Biol Med 2020; 160:368-375. [PMID: 32853720 DOI: 10.1016/j.freeradbiomed.2020.08.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 01/06/2023]
Abstract
We have previously shown that the retinal rod outer segments (OS) produce reactive oxygen species in the function of illumination in vitro, establishing a relationship among the extra-mitochondrial oxidative phosphorylation and phototransduction. This source of oxidative stress in the OS can be modulated by polyphenols, acting as inhibitors of F1Fo-ATP synthase. The present study aimed at exploring whether sclareol, a diterpene, interacts with F1Fo-ATP synthase mitigating the light-induced free radical production in the rod OS. Characterization of bovine retinal sections was conducted by immunogold analysis. Reactive oxygen intermediates production, oxygen consumption, the activity of the four respiratory complexes and ATP synthesis were evaluated in purified bovine rod OS. Molecular docking analyses were also conducted. Sclareol reduced free radical production by light-exposed rod OS. Such antioxidant effect was associated with an inhibition of the respiratory complexes and oxygen consumption (OCR), in coupled conditions. Sclareol also inhibited the rod OS ATP synthetic ability. Since the inhibitor effect on respiratory complexes and OCR is not observed in uncoupled conditions, it is supposed that the modulating effect of sclareol on the ectopic oxidative phosphorylation in the rod OS targets specifically the F1Fo-ATP synthase. This hypothesis is confirmed by the in silico molecular docking analyses, which shows that sclareol binds the F1 moiety of ATP synthase with high affinity. In conclusion, a beneficial effect of sclareol can be envisaged as a modulator of oxidative stress in the photoreceptor, a risk factor for the degenerative retinal diseases, suggestive of its potential beneficial action also in vivo.
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Affiliation(s)
- Silvia Ravera
- Dipartimento di Medicina Sperimentale, Università di Genoa, Via De Toni 14, 16132, Genova, Italy
| | - Alfonso Esposito
- Centro di Biologia Integrata (CIBIO), Università di Trento, Via Sommarive, 9, Povo, 38123, Trento, Italy
| | - Paolo Degan
- UOC Mutagenesi, IRCCS Policlinico San Martino -IST, Istituto Nazionale per La Ricerca Sul Cancro), Largo Rosanna Benzi 10, 16132, Genova, Italy
| | - Federico Caicci
- Dipartimento di Biologia, Università di Padova, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Daniela Calzia
- Dipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132, Genova, Italy
| | - Eleonora Perrotta
- Dipartimento di Medicina Sperimentale, Università di Genoa, Via De Toni 14, 16132, Genova, Italy
| | - Lucia Manni
- Dipartimento di Biologia, Università di Padova, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Angela Bisio
- Dipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132, Genova, Italy
| | - Valeria Iobbi
- Dipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132, Genova, Italy
| | - Anna Schito
- Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Università di Genova, Largo Rosanna Benzi 8, 16145, Genova, Italy
| | - Carlo Enrico Traverso
- Clinica Oculistica, (DINOGMI) Università di Genova, V.le Benedetto XV 6, 16132, Genova, Italy
| | - Isabella Panfoli
- Dipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132, Genova, Italy.
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Ravera S, Caicci F, Degan P, Maggi D, Manni L, Puddu A, Nicolò M, Traverso CE, Panfoli I. Inhibitory Action of Antidiabetic Drugs on the Free Radical Production by the Rod Outer Segment Ectopic Aerobic Metabolism. Antioxidants (Basel) 2020; 9:E1133. [PMID: 33203090 PMCID: PMC7696108 DOI: 10.3390/antiox9111133] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/04/2020] [Accepted: 11/12/2020] [Indexed: 12/17/2022] Open
Abstract
Rod outer segments (OS) express the FoF1-ATP synthase and the respiratory chain, conducting an ectopic aerobic metabolism that produces free radicals in vitro. Diabetic retinopathy, a leading cause of vision loss, is associated with oxidative stress in the outer retina. Since metformin and glibenclamide, two anti-type 2 diabetes drugs, target the respiratory complexes, we studied the effect of these two drugs, individually or in association, on the free radical production in purified bovine rod OS. ATP synthesis, oxygen consumption, and oxidative stress production were assayed by luminometry, oximetry and flow cytometry, respectively. The expression of FoF1-ATP synthase was studied by immunogold electron microscopy. Metformin had a hormetic effect on the OS complex I and ATP synthetic activities, being stimulatory at concentrations below 1 mM, and inhibitory above. Glibenclamide inhibited complexes I and III, as well as ATP production in a concentration-dependent manner. Maximal concentrations of both drugs inhibited the ROI production by the light-exposed OS. Data, consistent with the delaying effect of these drugs on the onset of diabetic retinopathy, suggest that a combination of the two drugs at the beginning of the treatment might reduce the oxidative stress production helping the endogenous antioxidant defences in avoiding retinal damage.
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Affiliation(s)
- Silvia Ravera
- Dipartimento di Medicina Sperimentale, Università di Genoa, Via De Toni 14, 16132 Genova, Italy;
| | - Federico Caicci
- Dipartimento di Biologia, Università di Padova, via U. Bassi 58/B, 35121 Padova, Italy; (F.C.); (L.M.)
| | - Paolo Degan
- U.O. Mutagenesis and Preventive Oncology, IRCCS Ospedale Policlinico San Martino, L.go R. Benzi, 10, 16132 Genova, Italy;
| | - Davide Maggi
- Department of Internal Medicine and Medical Specialties, University of Genova, 16132 Genova, Italy; (D.M.); (A.P.)
| | - Lucia Manni
- Dipartimento di Biologia, Università di Padova, via U. Bassi 58/B, 35121 Padova, Italy; (F.C.); (L.M.)
| | - Alessandra Puddu
- Department of Internal Medicine and Medical Specialties, University of Genova, 16132 Genova, Italy; (D.M.); (A.P.)
| | - Massimo Nicolò
- Clinica Oculistica (DINOGMI), Università di Genova, V.le Benedetto XV 6, 16132 Genova, Italy; (M.N.); (C.E.T.)
- Fondazione per la Macula onlus, Università di Genova, V.le Benedetto XV 6, 16132 Genova, Italy
| | - Carlo E. Traverso
- Clinica Oculistica (DINOGMI), Università di Genova, V.le Benedetto XV 6, 16132 Genova, Italy; (M.N.); (C.E.T.)
| | - Isabella Panfoli
- Dipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132 Genova, Italy
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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: 18] [Impact Index Per Article: 4.5] [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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Morelli AM, Ravera S, Calzia D, Panfoli I. An update of the chemiosmotic theory as suggested by possible proton currents inside the coupling membrane. Open Biol 2020; 9:180221. [PMID: 30966998 PMCID: PMC6501646 DOI: 10.1098/rsob.180221] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Understanding how biological systems convert and store energy is a primary purpose of basic research. However, despite Mitchell's chemiosmotic theory, we are far from the complete description of basic processes such as oxidative phosphorylation (OXPHOS) and photosynthesis. After more than half a century, the chemiosmotic theory may need updating, thanks to the latest structural data on respiratory chain complexes. In particular, up-to date technologies, such as those using fluorescence indicators following proton displacements, have shown that proton translocation is lateral rather than transversal with respect to the coupling membrane. Furthermore, the definition of the physical species involved in the transfer (proton, hydroxonium ion or proton currents) is still an unresolved issue, even though the latest acquisitions support the idea that protonic currents, difficult to measure, are involved. Moreover, FoF1-ATP synthase ubiquitous motor enzyme has the peculiarity (unlike most enzymes) of affecting the thermodynamic equilibrium of ATP synthesis. It seems that the concept of diffusion of the proton charge expressed more than two centuries ago by Theodor von Grotthuss is to be taken into consideration to resolve these issues. All these uncertainties remind us that also in biology it is necessary to consider the Heisenberg indeterminacy principle, which sets limits to analytical questions.
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Affiliation(s)
- Alessandro Maria Morelli
- 1 Pharmacy Department, Biochemistry Lab, University of Genova , Viale Benedetto XV 3, 16132 Genova , Italy
| | - Silvia Ravera
- 2 Experimental Medicine Department, University of Genova , Via De Toni 14, 16132 Genova , Italy
| | - Daniela Calzia
- 1 Pharmacy Department, Biochemistry Lab, University of Genova , Viale Benedetto XV 3, 16132 Genova , Italy
| | - Isabella Panfoli
- 2 Experimental Medicine Department, University of Genova , Via De Toni 14, 16132 Genova , 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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Calzia D, Degan P, Caicci F, Bruschi M, Manni L, Ramenghi LA, Candiano G, Traverso CE, Panfoli I. Modulation of the rod outer segment aerobic metabolism diminishes the production of radicals due to light absorption. Free Radic Biol Med 2018; 117:110-118. [PMID: 29378336 DOI: 10.1016/j.freeradbiomed.2018.01.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 01/17/2018] [Accepted: 01/23/2018] [Indexed: 12/19/2022]
Abstract
Oxidative stress is a primary risk factor for both inflammatory and degenerative retinopathies. Our previous data on blue light-irradiated retinas demonstrated an oxidative stress higher in the rod outer segment (OS) than in the inner limb, leading to impairment of the rod OS extra-mitochondrial aerobic metabolism. Here the oxidative metabolism and Reactive Oxygen Intermediates (ROI) production was evaluated in purified bovine rod OS in function of exposure to different illumination conditions. A dose response was observed to varying light intensities and duration in terms of both ROI production and ATP synthesis. Pretreatment with resveratrol, inhibitor of F1Fo-ATP synthase, or metformin, inhibitor of the respiratory complex I, significantly diminished the ROI production. Metformin also diminished the rod OS Complex I activity and reduced the maximal OS response to light in ATP production. Data show for the first time the relationship existing in the rod OS between its -aerobic- metabolism, light absorption, and ROI production. A beneficial effect was exerted by metformin and resveratrol, in modulating the ROI production in the illuminated rod OS, suggestive of their beneficial action also in vivo. Data shed new light on preventative interventions for cone loss secondary to rod damage due to oxidative stress.
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Affiliation(s)
- Daniela Calzia
- Dipartimento di Farmacia-DIFAR,-Biochemistry Lab., University of Genoa, V.le Benedetto XV 3, 16132 Genova, Italy.
| | - Paolo Degan
- UOC Mutagenesi, IRCCS AOU San Martino - IST (Istituto Nazionale per la Ricerca sul Cancro), Genova, Italy
| | - Federico Caicci
- Department of Biology, Università di Padova, via U. Bassi 58/B, 35121 Padova, Italy
| | - Maurizio Bruschi
- Laboratory of Pathophysiology of Uremia, Istituto Giannina Gaslini, Genova, Italy
| | - Lucia Manni
- Department of Biology, Università di Padova, via U. Bassi 58/B, 35121 Padova, Italy
| | - Luca A Ramenghi
- Neonatal Intensive Care Unit, U.O.S. Malattie Metaboliche, V.le Benedetto XV 6, Genova, Italy
| | - Giovanni Candiano
- Neonatal Intensive Care Unit, U.O.S. Malattie Metaboliche, V.le Benedetto XV 6, Genova, Italy
| | - Carlo Enrico Traverso
- Clinica Oculistica, (DINOGMI) University of Genoa, V.le Benedetto XV 6, Genova, Italy
| | - Isabella Panfoli
- Dipartimento di Farmacia-DIFAR,-Biochemistry Lab., University of Genoa, V.le Benedetto XV 3, 16132 Genova, Italy
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Vergara MN, Flores-Bellver M, Aparicio-Domingo S, McNally M, Wahlin KJ, Saxena MT, Mumm JS, Canto-Soler MV. Three-dimensional automated reporter quantification (3D-ARQ) technology enables quantitative screening in retinal organoids. Development 2017; 144:3698-3705. [PMID: 28870990 DOI: 10.1242/dev.146290] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 08/30/2017] [Indexed: 12/20/2022]
Abstract
The advent of stem cell-derived retinal organoids has brought forth unprecedented opportunities for developmental and physiological studies, while presenting new therapeutic promise for retinal degenerative diseases. From a translational perspective, organoid systems provide exciting new prospects for drug discovery, offering the possibility to perform compound screening in a three-dimensional (3D) human tissue context that resembles the native histoarchitecture and to some extent recapitulates cellular interactions. However, inherent variability issues and a general lack of robust quantitative technologies for analyzing organoids on a large scale pose severe limitations for their use in translational applications. To address this need, we have developed a screening platform that enables accurate quantification of fluorescent reporters in complex human iPSC-derived retinal organoids. This platform incorporates a fluorescence microplate reader that allows xyz-dimensional detection and fine-tuned wavelength selection. We have established optimal parameters for fluorescent reporter signal detection, devised methods to compensate for organoid size variability, evaluated performance and sensitivity parameters, and validated this technology for functional applications.
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Affiliation(s)
- M Natalia Vergara
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Miguel Flores-Bellver
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Silvia Aparicio-Domingo
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Minda McNally
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Karl J Wahlin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Meera T Saxena
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Jeff S Mumm
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - M Valeria Canto-Soler
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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Donor and host photoreceptors engage in material transfer following transplantation of post-mitotic photoreceptor precursors. Nat Commun 2016; 7:13029. [PMID: 27701378 PMCID: PMC5059468 DOI: 10.1038/ncomms13029] [Citation(s) in RCA: 202] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 08/23/2016] [Indexed: 12/12/2022] Open
Abstract
Photoreceptor replacement by transplantation is proposed as a treatment for blindness. Transplantation of healthy photoreceptor precursor cells into diseased murine eyes leads to the presence of functional photoreceptors within host retinae that express an array of donor-specific proteins. The resulting improvement in visual function was understood to be due to donor cells integrating within host retinae. Here, however, we show that while integration occurs the majority of donor-reporter-labelled cells in the host arises as a result of material transfer between donor and host photoreceptors. Material transfer does not involve permanent donor–host nuclear or cell–cell fusion, or the uptake of free protein or nucleic acid from the extracellular environment. Instead, RNA and/or protein are exchanged between donor and host cells in vivo. These data require a re-evaluation of the mechanisms underlying rescue by photoreceptor transplantation and raise the possibility of material transfer as a strategy for the treatment of retinal disorders. Transplantation of healthy photoreceptor cells has been shown to rescue blindness. Here, the authors show that rather than donor cells integrating into the host retina, the predominant mechanism underlying this rescue involves exchange of cytoplasmic material between donor and host cells in vivo.
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Calzia D, Oneto M, Caicci F, Bianchini P, Ravera S, Bartolucci M, Diaspro A, Degan P, Manni L, Traverso CE, Panfoli I. Effect of polyphenolic phytochemicals on ectopic oxidative phosphorylation in rod outer segments of bovine retina. Br J Pharmacol 2015; 172:3890-903. [PMID: 25917043 DOI: 10.1111/bph.13173] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 03/24/2015] [Accepted: 04/20/2015] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE The rod outer segments (OS) of the retina are specialized organelles where phototransduction takes place. The mitochondrial electron transport complexes I-IV, cytochrome c and Fo F1 -ATP synthase are functionally expressed in the OS disks. Here, we have studied the effect of some polyphenolic compounds acting as inhibitors of mitochondrial ATPase/synthase activity on the OS ectopic Fo F1 - ATP synthase. The mechanism of apoptosis in the OS was also investigated studying the expression of cytochrome c, caspase 9 and 3 and Apaf-1. EXPERIMENTAL APPROACH We prepared OS from fresh bovine retinae. Semi-quantitative Western blotting, confocal and electron microscopy, and cytofluorimetry were used along with biochemical analyses such as oximetry, ATP synthesis and hydrolysis. KEY RESULTS Resveratrol and curcumin plus piperine inhibited ATP synthesis and oxygen consumption in the OS. Epigallocatechin gallate and quercetin inhibited ATP hydrolysis and oxygen consumption in the OS. Malondialdehyde and hydrogen peroxide were produced in respiring OS in the presence of substrates. Cytochrome c was located inside the disk membranes. Procaspase 9 and 3, as well as Apaf-1 were expressed in the OS. CONCLUSIONS AND IMPLICATIONS These polyphenolic phytochemicals modulated the Fo F1 -ATP synthase activity of the the OS reducing production of reactive oxygen intermediates by the OS ectopic electron transport chain. Polyphenols decrease membrane peroxidation and cytochrome c release from disks, preventing the induction of caspase-dependent apoptosis in the OS Such effects are relevant in the design of protection against functional impairment of the OS following oxidative stress from exposure to intense illumination.
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Affiliation(s)
- Daniela Calzia
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy
| | - Michele Oneto
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy
| | | | - Paolo Bianchini
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy
| | - Silvia Ravera
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy
| | - Martina Bartolucci
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy
| | - Alberto Diaspro
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy
| | - Paolo Degan
- UOC Mutagenesi, IRCCS Azienda Ospedaliera Universitaria San Martino - Istituto Nazionale per la Ricerca sul Cancro, 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 - Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy
| | - Isabella Panfoli
- Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy
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Marquioni-Ramella MD, Suburo AM. Photo-damage, photo-protection and age-related macular degeneration. Photochem Photobiol Sci 2015. [DOI: 10.1039/c5pp00188a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The course of Age-related Macular Degeneration (AMD) is described as the effect of light (400–580 nm) on various molecular targets in photoreceptors and the retinal pigment epithelium (RPE). Photo-damage is followed by inflammation, increasing oxidative stress and, probably, unveiling new photosensitive molecules.
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Affiliation(s)
| | - Angela M. Suburo
- Medicina Celular y Molecular
- Facultad de Ciencias Biomédicas
- Universidad Austral
- Pilar B1629AHJ
- Argentina
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14
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Roehlecke C, Schumann U, Ader M, Brunssen C, Bramke S, Morawietz H, Funk RHW. Stress reaction in outer segments of photoreceptors after blue light irradiation. PLoS One 2013; 8:e71570. [PMID: 24039718 PMCID: PMC3770596 DOI: 10.1371/journal.pone.0071570] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 07/07/2013] [Indexed: 12/26/2022] Open
Abstract
The retina is prone to oxidative stress from many factors which are also involved in the pathogenesis of degenerative diseases. In this study, we used the application of blue light as a physiological stress factor. The aim of this study was to identify the major source of intracellular ROS that mediates blue light-induced detrimental effects on cells which may lead to cytotoxicity. We hypothesized that outer segments are the major source of blue light induced ROS generation. In photoreceptors, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) enzymes and the recently found respiratory chain complexes may represent a major source for reactive oxygen species (ROS), beside mitochondria and chromophores. Therefore, we investigated this hypothesis and analysed the exact localization of the ROS source in photoreceptors in an organotypic culture system for mouse retinas. Whole eyeball cultures were irradiated with visible blue light (405 nm) with an output power of 1 mW/cm2. Blue light impingement lead to an increase of ROS production (detected by H2DCFDA in live retinal explants), which was particularly strong in the photoreceptor outer segments. Nox-2 and Nox-4 proteins are sources of ROS in blue light irradiated photoreceptors; the Nox inhibitor apocynin decreased ROS stimulated by blue light. Concomitantly, enzyme SOD-1, a member of the antioxidant defense system, indicator molecules of protein oxidation (CML) and lipid oxidation (MDA and 4-HNE) were also increased in the outer segments. Interestingly, outer segments showed a mitochondrial-like membrane potential which was demonstrated using two dyes (JC-1 and TMRE) normally exclusively associated with mitochondria. As in mitochondria, these dyes indicated a decrease of the membrane potential in hypoxic states or cell stress situations. The present study demonstrates that ROS generation and oxidative stress occurs directly in the outer segments of photoreceptors after blue light irradiation.
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Affiliation(s)
- Cora Roehlecke
- Institute of Anatomy, Technische Universität (TU) Dresden, Dresden, Germany
- * E-mail:
| | - Ulrike Schumann
- Institute of Anatomy, Technische Universität (TU) Dresden, Dresden, Germany
| | - Marius Ader
- Center for Regenerative Therapies Dresden (CRTD) DFG – Cluster of Excellence, Biotechnology Center, Dresden, Germany
| | - Coy Brunssen
- Division of Vascular Endothelium and Microcirculation, Department of Medicine III, TU Dresden, Dresden, Germany
| | - Silvia Bramke
- Institute of Anatomy, Technische Universität (TU) Dresden, Dresden, Germany
| | - Henning Morawietz
- Center for Regenerative Therapies Dresden (CRTD) DFG – Cluster of Excellence, Biotechnology Center, Dresden, Germany
- Division of Vascular Endothelium and Microcirculation, Department of Medicine III, TU Dresden, Dresden, Germany
| | - Richard H. W. Funk
- Institute of Anatomy, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD) DFG – Cluster of Excellence, Biotechnology Center, Dresden, Germany
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15
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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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16
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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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17
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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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18
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Abstract
Nervous system is a great oxygen consumer, but the site of oxygen absorption has remained elusive. Four proteomic studies have shown that the respiratory complexes I to V may be expressed in isolated myelin. Myelin is an outgrowth of glial cells, surrounding many axons in multiple spires both in peripheral and central nervous system. Recent quantitative analyses strongly support the daring hypothesis that myelin is functional in aerobic ATP production, to supply the neuron with chemical energy. A vision of myelin sheath as a structure devoted to the oxygen absorbance for glucose combustion in nervous system thank to its enormous surface, would be also supported by an impressive series of characteristics and properties of myelin that do not presently find an explanation, all of which are herein examined.
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Affiliation(s)
- Alessandro Morelli
- Department of Biology, Faculty of Sciences, University of Genova, Viale Benedetto XV-3, 16132 Genoa, Italy.
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19
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Qu J, Ma L, Washington I. Retinal coenzyme Q in the bovine eye. Biofactors 2011; 37:393-8. [PMID: 21989945 DOI: 10.1002/biof.166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/14/2011] [Accepted: 04/04/2011] [Indexed: 11/07/2022]
Abstract
Coenzyme Q plays an integral role in oxygen metabolism and management, and there is a positive correlation between low tissue coenzyme Q concentrations and the progression of many degenerative diseases. Retinal oxidative damage plays a role in the pathogenesis of many degenerative eye diseases; nevertheless, despite the retina's high rate of oxygen metabolism, there is little data relating to retinal coenzyme Q concentrations. In this study, we quantified coenzyme Q in the model bovine eye and determined whether it could function as a retinal lipid antioxidant. We found that the neural retina's ubiquinone concentration exceeded those of the vitreous humor, lens, choroid, and extraocular muscle, but it was lower than those measured in heart, kidney, liver, and brain tissues. Ubiquinol was found to be as effective as vitamin E as a retinal lipid antioxidant. The overall relatively low levels of ubiquinone found in the retina, coupled with the retina's need for lipid antioxidants and oxidative metabolism, suggests that retinal function might be sensitive to changes in ubiquinone concentrations.
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Affiliation(s)
- Jinfeng Qu
- Department of Ophthalmology, People Hospital of Peking University, Beijing, China
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20
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Ozkucur N, Epperlein HH, Funk RHW. Ion imaging during axolotl tail regeneration in vivo. Dev Dyn 2010; 239:2048-57. [PMID: 20549718 DOI: 10.1002/dvdy.22323] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Several studies have reported that endogenous ion currents are involved in a wide range of biological processes from single cell and tissue behavior to regeneration. Various methods are used to assess intracellular and local ion dynamics in biological systems, e.g., patch clamping and vibrating probes. Here, we introduce an approach to detect ion kinetics in vivo using a noninvasive method that can electrophysiologically characterize an entire experimental tissue region or organism. Ion-specific vital dyes have been successfully used for live imaging of intracellular ion dynamics in vitro. Here, we demonstrate that cellular pH, cell membrane potential, calcium, sodium and potassium can be monitored in vivo during tail regeneration in the axolotl (Ambystoma mexicanum) using ion-specific vital dyes. Thus, we suggest that ion-specific vital dyes can be a powerful tool to obtain electrophysiological data during crucial biological events in vivo.
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Affiliation(s)
- Nurdan Ozkucur
- Department of Anatomy, Medical Faculty Carl Gustav Carus, TU Dresden, Fetscherstrasse 74, Dresden, Germany.
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21
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Panfoli I, Calzia D, Ravera S, Bianchini P, Diaspro A. Immunochemical or fluorescent labeling of vesicular subcellular fractions for microscopy imaging. Microsc Res Tech 2010; 73:1086-90. [DOI: 10.1002/jemt.20852] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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22
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Blood pressure treatment in acute ischemic stroke: a review of studies and recommendations. Curr Opin Neurol 2010; 23:46-52. [PMID: 20038827 DOI: 10.1097/wco.0b013e3283355694] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW Elevated blood pressure (BP) is frequent in patients with acute ischemic stroke. Pathophysiological data support its usefulness to maintain adequate perfusion of the ischemic penumba. This review article aims to summarize the available evidence from clinical studies that examined the prognostic role of BP during the acute phase of ischemic stroke and intervention studies that assessed the efficacy of active BP alteration. RECENT FINDINGS We found 34 observational studies (33,470 patients), with results being inconsistent among the studies; most studies reported a negative association between increased levels of BP and clinical outcome, whereas a few studies showed clinical improvement with higher BP levels, clinical deterioration with decreased BP, or no association at all. Similarly, the conclusions drawn by the 18 intervention studies included in this review (1637 patients) were also heterogeneous. Very recent clinical data suggest a possible beneficial effect of early treatment with some antihypertensives on late clinical outcome. SUMMARY Observational and interventional studies of management of acute poststroke hypertension yield conflicting results. We discuss different explanations that may account for this and discuss the current guidelines and pathophysiological considerations for the management of acute poststroke hypertension.
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Evidence for aerobic metabolism in retinal rod outer segment disks. Int J Biochem Cell Biol 2009; 41:2555-65. [PMID: 19715769 DOI: 10.1016/j.biocel.2009.08.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 08/11/2009] [Accepted: 08/20/2009] [Indexed: 12/15/2022]
Abstract
The disks of the vertebrate retinal rod Outer Segment (OS), devoid of mitochondria, are the site of visual transduction, a very energy demanding process. In a previous proteomic study we reported the expression of the respiratory chain complexes I-IV and the oxidative phosphorylation Complex V (F(1)F(0)-ATP synthase) in disks. In the present study, the functional localization of these proteins in disks was investigated by biochemical analyses, oxymetry, membrane potential measurements, and confocal laser scanning microscopy. Disk preparations, isolated by Ficoll flotation, were characterized for purity. An oxygen consumption, stimulated by NADH and Succinate and reverted by rotenone, antimycin A and KCN was measured in disks, either in coupled or uncoupled conditions. Rhodamine-123 fluorescence quenching kinetics showed the existence of a proton potential difference across the disk membranes. Citrate synthase activity was assayed and found enriched in disks with respect to ROS. ATP synthesis by disks (0.7 micromol ATP/min/mg), sensitive to the common mitochondrial ATP synthase inhibitors, would largely account for the rod ATP need in the light. Overall, data indicate that an oxidative phosphorylation occurs in rod OS, which do not contain mitochondria, thank to the presence of ectopically located mitochondrial proteins. These findings may provide important new insight into energy production in outer segments via aerobic metabolism and additional information about protein components in OS disk membranes.
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Evidence for aerobic ATP synthesis in isolated myelin vesicles. Int J Biochem Cell Biol 2009; 41:1581-91. [PMID: 19401152 DOI: 10.1016/j.biocel.2009.01.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/15/2008] [Accepted: 01/14/2009] [Indexed: 11/23/2022]
Abstract
Even though brain represents only 2-3% of the body weight, it consumes 20% of total body oxygen, and 25% of total body glucose. This sounds surprising, in that mitochondrial density in brain is low, while mitochondria are thought to be the sole site of aerobic energy supply. These data would suggest that structures other than mitochondria are involved in aerobic ATP production. Considering that a sustained aerobic metabolism needs a great surface extension and that the oxygen solubility is higher in neutral lipids, we have focused our attention on myelin sheath, the multilayered membrane produced by oligodendrocytes, hypothesizing it to be an ATP production site. Myelin has long been supposed to augment the speed of conduction, however, there is growing evidence that it exerts an as yet unexplained neuro-trophic role. In this work, by biochemical assays, Western Blot analysis, confocal laser microscopy, we present evidence that isolated myelin vesicles (IMV) are able to consume O(2) and produce ATP through the operation of a proton gradient across their membranes. Living optic nerve sections were exposed to MitoTracker, a classical mitochondrial dye, by a technique that we have developed and it was found that structures closely resembling nerve axons were stained. By immunohistochemistry we show that ATP synthase and myelin basic protein colocalize on both IMV and optic nerves. The complex of data suggests that myelin sheath may be the site of oxygen absorption and aerobic metabolism for the axons.
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