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Broad spectrum metabolomics for detection of abnormal metabolic pathways in a mouse model for retinitis pigmentosa. Exp Eye Res 2019; 184:135-145. [PMID: 30885711 DOI: 10.1016/j.exer.2019.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/07/2019] [Accepted: 03/11/2019] [Indexed: 02/05/2023]
Abstract
Retinitis pigmentosa (RP) is a degenerative disease of the retina that affects approximately 1 million people worldwide. There are multiple genetic causes of this disease, for which, at present, there are no effective therapeutic strategies. In the present report, we utilized broad spectrum metabolomics to identify perturbations in the metabolism of the rd10 mouse, a genetic model for RP that contains a mutation in Pde6β. These data provide novel insights into mechanisms that are potentially critical for retinal degeneration. C57BL/6J and rd10 mice were raised in cyclic light followed by either light or dark adaptation at postnatal day (P) 18, an early stage in the degeneration process. Mice raised entirely in the dark until P18 were also evaluated. After euthanasia, retinas were removed and extracted for analysis by ultra-performance liquid chromatography-time of flight-mass spectrometry (UPLC-QTOF-MS). Compared to wild type mice, rd10 mice raised in cyclic light or in complete darkness demonstrate significant alterations in retinal pyrimidine and purine nucleotide metabolism, potentially disrupting deoxynucleotide pools necessary for mitochondrial DNA replication. Other metabolites that demonstrate significant increases are the Coenzyme A intermediate, 4'-phosphopantothenate, and acylcarnitines. The changes in these metabolites, identified for the first time in a model of RP, are highly likely to disrupt normal energy metabolism. High levels of nitrosoproline were also detected in rd10 retinas relative to those from wild type mice. These results suggest that nitrosative stress may be involved in retinal degeneration in this mouse model.
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Xiang Z, Bao Y, Zhang J, Liu C, Xu D, Liu F, Chen H, He L, Ramakrishna S, Zhang Z, Vardi N, Xu Y. Inhibition of non-NMDA ionotropic glutamate receptors delays the retinal degeneration in rd10 mouse. Neuropharmacology 2018; 139:137-149. [DOI: 10.1016/j.neuropharm.2018.06.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 06/13/2018] [Accepted: 06/21/2018] [Indexed: 11/26/2022]
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Vinberg F, Chen J, Kefalov VJ. Regulation of calcium homeostasis in the outer segments of rod and cone photoreceptors. Prog Retin Eye Res 2018; 67:87-101. [PMID: 29883715 DOI: 10.1016/j.preteyeres.2018.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/30/2018] [Accepted: 06/04/2018] [Indexed: 12/11/2022]
Abstract
Calcium plays important roles in the function and survival of rod and cone photoreceptor cells. Rapid regulation of calcium in the outer segments of photoreceptors is required for the modulation of phototransduction that drives the termination of the flash response as well as light adaptation in rods and cones. On a slower time scale, maintaining proper calcium homeostasis is critical for the health and survival of photoreceptors. Decades of work have established that the level of calcium in the outer segments of rods and cones is regulated by a dynamic equilibrium between influx via the transduction cGMP-gated channels and extrusion via rod- and cone-specific Na+/Ca2+, K+ exchangers (NCKXs). It had been widely accepted that the only mechanism for extrusion of calcium from rod outer segments is via the rod-specific NCKX1, while extrusion from cone outer segments is driven exclusively by the cone-specific NCKX2. However, recent evidence from mice lacking NCKX1 and NCKX2 have challenged that notion and have revealed a more complex picture, including a NCKX-independent mechanism in rods and two separate NCKX-dependent mechanisms in cones. This review will focus on recent findings on the molecular mechanisms of extrusion of calcium from the outer segments of rod and cone photoreceptors, and the functional and structural changes in photoreceptors when normal extrusion is disrupted.
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Affiliation(s)
- Frans Vinberg
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA; John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
| | - Vladimir J Kefalov
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.
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Vighi E, Trifunović D, Veiga-Crespo P, Rentsch A, Hoffmann D, Sahaboglu A, Strasser T, Kulkarni M, Bertolotti E, van den Heuvel A, Peters T, Reijerkerk A, Euler T, Ueffing M, Schwede F, Genieser HG, Gaillard P, Marigo V, Ekström P, Paquet-Durand F. Combination of cGMP analogue and drug delivery system provides functional protection in hereditary retinal degeneration. Proc Natl Acad Sci U S A 2018; 115:E2997-E3006. [PMID: 29531030 PMCID: PMC5879685 DOI: 10.1073/pnas.1718792115] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Inherited retinal degeneration (RD) is a devastating and currently untreatable neurodegenerative condition that leads to loss of photoreceptor cells and blindness. The vast genetic heterogeneity of RD, the lack of "druggable" targets, and the access-limiting blood-retinal barrier (BRB) present major hurdles toward effective therapy development. Here, we address these challenges (i) by targeting cGMP (cyclic guanosine- 3',5'-monophosphate) signaling, a disease driver common to different types of RD, and (ii) by combining inhibitory cGMP analogs with a nanosized liposomal drug delivery system designed to facilitate transport across the BRB. Based on a screen of several cGMP analogs we identified an inhibitory cGMP analog that interferes with activation of photoreceptor cell death pathways. Moreover, we found liposomal encapsulation of the analog to achieve efficient drug targeting to the neuroretina. This pharmacological treatment markedly preserved in vivo retinal function and counteracted photoreceptor degeneration in three different in vivo RD models. Taken together, we show that a defined class of compounds for RD treatment in combination with an innovative drug delivery method may enable a single type of treatment to address genetically divergent RD-type diseases.
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Affiliation(s)
- Eleonora Vighi
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, 41125 Modena, Italy
| | - Dragana Trifunović
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Patricia Veiga-Crespo
- Ophthalmology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, 22184 Lund, Sweden
| | - Andreas Rentsch
- BIOLOG Life Science Institute Forschungslabor und Biochemica-Vertrieb GmbH, 28199 Bremen, Germany
| | - Dorit Hoffmann
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, 41125 Modena, Italy
| | - Ayse Sahaboglu
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Torsten Strasser
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Manoj Kulkarni
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
- Centre for Integrative Neuroscience, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Evelina Bertolotti
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, 41125 Modena, Italy
| | | | - Tobias Peters
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | | | - Thomas Euler
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
- Centre for Integrative Neuroscience, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Marius Ueffing
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Frank Schwede
- BIOLOG Life Science Institute Forschungslabor und Biochemica-Vertrieb GmbH, 28199 Bremen, Germany
| | - Hans-Gottfried Genieser
- BIOLOG Life Science Institute Forschungslabor und Biochemica-Vertrieb GmbH, 28199 Bremen, Germany
| | - Pieter Gaillard
- to-BBB technologies BV, 2333 CH Leiden, The Netherlands
- 2-BBB Medicines BV, 2333 CH Leiden, The Netherlands
| | - Valeria Marigo
- Dipartimento di Scienze della Vita, Università degli Studi di Modena e Reggio Emilia, 41125 Modena, Italy;
| | - Per Ekström
- Ophthalmology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, 22184 Lund, Sweden;
| | - François Paquet-Durand
- Forschungsinstitut für Augenheilkunde, Department für Augenheilkunde, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany;
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55
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Trifunović D, Arango-Gonzalez B, Comitato A, Barth M, Del Amo EM, Kulkarni M, Sahaboglu A, Hauck SM, Urtti A, Arsenijevic Y, Ueffing M, Marigo V, Paquet-Durand F. HDAC inhibition in the cpfl1 mouse protects degenerating cone photoreceptors in vivo. Hum Mol Genet 2018; 25:4462-4472. [PMID: 28172811 DOI: 10.1093/hmg/ddw275] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 08/05/2016] [Accepted: 08/11/2016] [Indexed: 12/21/2022] Open
Abstract
Cone photoreceptor cell death as it occurs in certain hereditary retinal diseases is devastating, with the affected patients suffering from a loss of accurate and colour vision. Regrettably, these hereditary cone diseases are still untreatable to date. Thus, the identification of substances able to block or restrain cone cell death is of primary importance. We studied the neuroprotective effects of a histone deacetylase inhibitor, Trichostatin A (TSA), in a mouse model of inherited, primary cone degeneration (cpfl1). We show that HDAC inhibition protects cpfl1 cones in vitro, in retinal explant cultures. More importantly, in vivo, a single intravitreal TSA injection significantly increased cone survival for up to 16 days post-injection. In addition, the abnormal, incomplete cone migration pattern in the cpfl1 retina was significantly improved by HDAC inhibition. These findings suggest a crucial role for HDAC activity in primary cone degeneration and highlight a new avenue for future therapy developments for cone dystrophies and retinal diseases associated with impaired cone migration.
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Affiliation(s)
- Dragana Trifunović
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | | | - Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Melanie Barth
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Eva M Del Amo
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Manoj Kulkarni
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Ayse Sahaboglu
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Center Munich, Neuherberg, Germany
| | - Arto Urtti
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland.,Centre for Drug Research, Division of Pharmaceutical Bioscience, University of Helsinki, Helsinki, Finland
| | - Yvan Arsenijevic
- Unit of Gene Therapy & Stem Cell Biology, Hôpital Ophtalmique Jules Gonin, University of Lausanne, Lausanne, Switzerland
| | - Marius Ueffing
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
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56
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GUCY2D Cone-Rod Dystrophy-6 Is a "Phototransduction Disease" Triggered by Abnormal Calcium Feedback on Retinal Membrane Guanylyl Cyclase 1. J Neurosci 2018; 38:2990-3000. [PMID: 29440533 DOI: 10.1523/jneurosci.2985-17.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/19/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022] Open
Abstract
The Arg838Ser mutation in retinal membrane guanylyl cyclase 1 (RetGC1) has been linked to autosomal dominant cone-rod dystrophy type 6 (CORD6). It is believed that photoreceptor degeneration is caused by the altered sensitivity of RetGC1 to calcium regulation via guanylyl cyclase activating proteins (GCAPs). To determine the mechanism by which this mutation leads to degeneration, we investigated the structure and function of rod photoreceptors in two transgenic mouse lines, 362 and 379, expressing R838S RetGC1. In both lines, rod outer segments became shorter than in their nontransgenic siblings by 3-4 weeks of age, before the eventual photoreceptor degeneration. Despite the shortening of their outer segments, the dark current of transgenic rods was 1.5-2.2-fold higher than in nontransgenic controls. Similarly, the dim flash response amplitude in R838S+ rods was larger, time to peak was delayed, and flash sensitivity was increased, all suggesting elevated dark-adapted free cGMP in transgenic rods. In rods expressing R838S RetGC1, dark-current noise increased and the exchange current, detected after a saturating flash, became more pronounced. These results suggest disrupted Ca2+ phototransduction feedback and abnormally high free-Ca2+ concentration in the outer segments. Notably, photoreceptor degeneration, which typically occurred after 3 months of age in R838S RetGC1 transgenic mice in GCAP1,2+/+ or GCAP1,2+/- backgrounds, was prevented in GCAP1,2-/- mice lacking Ca2+ feedback to guanylyl cyclase. In summary, the dysregulation of guanylyl cyclase in RetGC1-linked CORD6 is a "phototransduction disease," which means it is associated with increased free-cGMP and Ca2+ levels in photoreceptors.SIGNIFICANCE STATEMENT In a mouse model expressing human membrane guanylyl cyclase 1 (RetGC1, GUCY2D), a mutation associated with early progressing congenital blindness, cone-rod dystrophy type 6 (CORD6), deregulates calcium-sensitive feedback of phototransduction to the cyclase mediated by guanylyl cyclase activating proteins (GCAPs), which are calcium-sensor proteins. The abnormal calcium sensitivity of the cyclase increases cGMP-gated dark current in the rod outer segments, reshapes rod photoresponses, and triggers photoreceptor death. This work is the first to demonstrate a direct physiological effect of GUCY2D CORD6-linked mutation on photoreceptor physiology in vivo It also identifies the abnormal regulation of the cyclase by calcium-sensor proteins as the main trigger for the photoreceptor death.
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57
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Involvement of Innate Immune System in Late Stages of Inherited Photoreceptor Degeneration. Sci Rep 2017; 7:17897. [PMID: 29263354 PMCID: PMC5738376 DOI: 10.1038/s41598-017-18236-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 12/05/2017] [Indexed: 01/10/2023] Open
Abstract
Retinitis pigmentosa (RP) is a group of inherited retinal degenerations that lead to progressive vision loss. Many mutations in 60 different genes have been shown to cause RP. Given the diversity of genes and mutations that cause RP, corrective gene therapy approaches currently in development may prove both time-consuming and cost-prohibitive for treatment of all forms of RP. An alternative approach is to find common biological pathways that cause retinal degeneration in various forms of RP, and identify new molecular targets. With this goal, we analyzed the retinal transcriptome of two non-allelic forms of RP in dogs, rcd1 and xlpra2, at clinically relevant advanced stages of the two diseases. Both diseases showed very similar trends in changes in gene expression compared to control normal dogs. Pathway analysis revealed upregulation of various components of the innate immune system in both diseases, including inflammasome and complement pathways. Our results show that the retinal transcriptome at advanced stages of RP is very similar to that of other retinal degenerative diseases such as age-related macular degeneration and diabetic retinopathy. Thus, drugs and therapeutics already in development for targeting these retinopathies may also prove useful for the treatment of many forms of RP.
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58
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Wang T, Tsang SH, Chen J. Two pathways of rod photoreceptor cell death induced by elevated cGMP. Hum Mol Genet 2017; 26:2299-2306. [PMID: 28379353 DOI: 10.1093/hmg/ddx121] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/22/2017] [Indexed: 11/14/2022] Open
Abstract
Cyclic-GMP is a second messenger in phototransduction, a G-protein signaling cascade that conveys photon absorption by rhodopsin to a change in current at the rod photoreceptor outer segment plasma membrane. Basal cGMP level is strictly controlled by the opposing actions of phosphodiesterase (PDE6) and retinal guanylyl cyclases (GCs), and mutations in genes that disrupt cGMP homeostasis leads to retinal degeneration in humans through mechanisms that are incompletely understood. The purpose of this study is to examine two distinct cellular targets of cGMP: the cGMP-gated (CNG) channels and protein kinase G (PRKG), and how each may contribute to rod cell death. Using a mouse genetic approach, we found that abolishing expression of CNG channels prolongs rod survival caused by elevated cGMP in a PDE6 mutant mouse model. This observation supports the use of channel blockers to delay rod death, which is expected to prolong useful vision through enhanced cone survival. However, the absence of CNG channel alone also caused abnormal cGMP accumulation. In a mouse model of CNG channel loss-of-function, abolishing PRKG1 expression had a long-lasting effect in promoting rod cell survival. Our data strongly implicate two distinct cGMP-mediated cell death pathways, and suggest that therapeutic designs targeting both pathways will be more effective at slowing photoreceptor cell death caused by elevated cGMP.
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Affiliation(s)
- Tian Wang
- Zilkha Neurogenetic Institute, Department of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Stephen H Tsang
- Jonas Children's Vision Care, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, NY 10032, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, NY 10032, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Department of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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59
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Iribarne M, Masai I. Neurotoxicity of cGMP in the vertebrate retina: from the initial research on rd mutant mice to zebrafish genetic approaches. J Neurogenet 2017; 31:88-101. [PMID: 28812418 DOI: 10.1080/01677063.2017.1358268] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Zebrafish are an excellent animal model for research on vertebrate development and human diseases. Sophisticated genetic tools including large-scale mutagenesis methodology make zebrafish useful for studying neuronal degenerative diseases. Here, we review zebrafish models of inherited ophthalmic diseases, focusing on cGMP metabolism in photoreceptors. cGMP is the second messenger of phototransduction, and abnormal cGMP levels are associated with photoreceptor death. cGMP concentration represents a balance between cGMP phosphodiesterase 6 (PDE6) and guanylate cyclase (GC) activities in photoreceptors. Various zebrafish cGMP metabolism mutants were used to clarify molecular mechanisms by which dysfunctions in this pathway trigger photoreceptor degeneration. Here, we review the history of research on the retinal degeneration (rd) mutant mouse, which carries a genetic mutation of PDE6b, and we also highlight recent research in photoreceptor degeneration using zebrafish models. Several recent discoveries that provide insight into cGMP toxicity in photoreceptors are discussed.
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Affiliation(s)
- Maria Iribarne
- a Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa , Japan
| | - Ichiro Masai
- a Okinawa Institute of Science and Technology Graduate University , Onna, Okinawa , Japan
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60
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Sahaboglu A, Sharif A, Feng L, Secer E, Zrenner E, Paquet-Durand F. Temporal progression of PARP activity in the Prph2 mutant rd2 mouse: Neuroprotective effects of the PARP inhibitor PJ34. PLoS One 2017; 12:e0181374. [PMID: 28723922 PMCID: PMC5517001 DOI: 10.1371/journal.pone.0181374] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/29/2017] [Indexed: 12/30/2022] Open
Abstract
Peripherin (peripherin/rds) is a membrane-associated protein that plays a critical role in the morphogenesis of rod and cone photoreceptor outer segments. Mutations in the corresponding PRPH2 gene cause different types of retinal dystrophies characterized by a loss of photoreceptors. Over activation of poly-ADP-ribose polymerase (PARP) was previously shown to be involved in different animal models for hereditary retinal dystrophies. This includes the rd2 mouse, which suffers from a human homologous mutation in the PRPH2 gene. In the present study, we show that increased retinal PARP activity and poly-ADP-ribosylation of proteins occurs before the peak of rd2 photoreceptor degeneration. Inhibition of PARP activity with the well-characterized PARP inhibitor PJ34 decreased the levels of poly-ADP-ribosylation and photoreceptor cell death. These results suggest a causal involvement of PARP in photoreceptor degeneration caused by peripherin mutations and highlight the possibility to use PARP inhibition for the mutation-independent treatment of hereditary retinal dystrophies.
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Affiliation(s)
- Ayse Sahaboglu
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- * E-mail: (AS); (FPD)
| | - Alaa Sharif
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Graduate Training Center of Neuroscience, Tuebingen, Germany
| | - Lili Feng
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Enver Secer
- Department of Medical Genetics, Erciyes University, Kayseri, Turkey
| | - Eberhart Zrenner
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany
| | - François Paquet-Durand
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- * E-mail: (AS); (FPD)
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61
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Gopalakrishna KN, Boyd K, Artemyev NO. Mechanisms of mutant PDE6 proteins underlying retinal diseases. Cell Signal 2017; 37:74-80. [PMID: 28583373 DOI: 10.1016/j.cellsig.2017.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 05/30/2017] [Accepted: 06/01/2017] [Indexed: 12/15/2022]
Abstract
Mutations in PDE6 genes encoding the effector enzymes in rods and cones underlie severe retinal diseases including retinitis pigmentosa (RP), autosomal dominant congenital stationary night blindness (adCSNB), and achromatopsia (ACHM). Here we examined a spectrum of pathogenic missense mutations in PDE6 using the system based on co-expression of cone PDE6C with its specialized chaperone AIPL1 and the regulatory Pγ subunit as a potent co-chaperone. We uncovered two mechanisms of PDE6C mutations underlying ACHM: (a) folding defects leading to expression of catalytically inactive proteins and (b) markedly diminished ability of Pγ to co-chaperone mutant PDE6C proteins thereby dramatically reducing the levels of functional enzyme. The mechanism of the Rambusch adCSNB associated with the H258N substitution in PDE6B was probed through the analysis of the model mutant PDE6C-H262N. We identified two interrelated deficits of PDE6C-H262N: disruption of the inhibitory interaction of Pγ with mutant PDE6C that markedly reduced the ability of Pγ to augment the enzyme folding. Thus, we conclude that the Rambusch adCSNB is triggered by low levels of the constitutively active PDE6. Finally, we examined PDE6C-L858V, which models PDE6B-L854V, an RP-linked mutation that alters the protein isoprenyl modification. This analysis suggests that the type of prenyl modifications does not impact the folding of PDE6, but it modulates the enzyme affinity for its trafficking partner PDE6D. Hence, the pathogenicity of PDE6B-L854V likely arises from its trafficking deficiency. Taken together, our results demonstrate the effectiveness of the PDE6C expression system to evaluate pathogenicity and elucidate the mechanisms of PDE6 mutations in retinal diseases.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Color Vision Defects/genetics
- Color Vision Defects/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 6/analysis
- Cyclic Nucleotide Phosphodiesterases, Type 6/genetics
- Cyclic Nucleotide Phosphodiesterases, Type 6/metabolism
- Eye Diseases, Hereditary/genetics
- Eye Diseases, Hereditary/metabolism
- Eye Proteins/analysis
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- HEK293 Cells
- Humans
- Mice
- Models, Molecular
- Mutation, Missense
- Myopia/genetics
- Myopia/metabolism
- Night Blindness/genetics
- Night Blindness/metabolism
- Protein Folding
- Protein Prenylation
- Retinal Diseases/genetics
- Retinal Diseases/metabolism
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Affiliation(s)
- Kota N Gopalakrishna
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States.
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62
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Olivares-González L, Martínez-Fernández de la Cámara C, Hervás D, Marín MP, Lahoz A, Millán JM, Rodrigo R. cGMP-Phosphodiesterase Inhibition Prevents Hypoxia-Induced Cell Death Activation in Porcine Retinal Explants. PLoS One 2016; 11:e0166717. [PMID: 27861632 PMCID: PMC5115799 DOI: 10.1371/journal.pone.0166717] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 11/02/2016] [Indexed: 12/11/2022] Open
Abstract
Retinal hypoxia and oxidative stress are involved in several retinal degenerations including diabetic retinopathy, glaucoma, central retinal artery occlusion, or retinopathy of prematurity. The second messenger cyclic guanosine monophosphate (cGMP) has been reported to be protective for neuronal cells under several pathological conditions including ischemia/hypoxia. The purpose of this study was to evaluate whether the accumulation of cGMP through the pharmacological inhibition of phosphodiesterase (PDE) with Zaprinast prevented retinal degeneration induced by mild hypoxia in cultures of porcine retina. Exposure to mild hypoxia (5% O2) for 24h reduced cGMP content and induced retinal degeneration by caspase dependent and independent (PARP activation) mechanisms. Hypoxia also produced a redox imbalance reducing antioxidant response (superoxide dismutase and catalase activities) and increasing superoxide free radical release. Zaprinast reduced mild hypoxia-induced cell death through inhibition of caspase-3 or PARP activation depending on the cell layer. PDE inhibition also ameliorated the effects of mild hypoxia on antioxidant response and the release of superoxide radical in the photoreceptor layer. The use of a PKG inhibitor, KT5823, suggested that cGMP-PKG pathway is involved in cell survival and antioxidant response. The inhibition of PDE, therefore, could be useful for reducing retinal degeneration under hypoxic/ischemic conditions.
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Affiliation(s)
- Lorena Olivares-González
- Grupo de Biomedicina Molecular, Celular y Genómica, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
| | | | - David Hervás
- Unidad de Bioestadística, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
| | - María Pilar Marín
- Unidad de Microscopía, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
| | - Agustin Lahoz
- Unidad de Hepatología Experimental, Unidad Analítica, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
| | - José María Millán
- Grupo de Biomedicina Molecular, Celular y Genómica, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Regina Rodrigo
- Grupo de Biomedicina Molecular, Celular y Genómica, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
- CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
- * E-mail:
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63
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Bauer PM, Zalis MC, Abdshill H, Deierborg T, Johansson F, Englund-Johansson U. Inflamed In Vitro Retina: Cytotoxic Neuroinflammation and Galectin-3 Expression. PLoS One 2016; 11:e0161723. [PMID: 27612287 PMCID: PMC5017668 DOI: 10.1371/journal.pone.0161723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/10/2016] [Indexed: 12/20/2022] Open
Abstract
Background Disease progression in retinal neurodegeneration is strongly correlated to immune cell activation, which may have either a neuroprotective or neurotoxic effect. Increased knowledge about the immune response profile and retinal neurodegeneration may lead to candidate targets for treatments. Therefore, we have used the explanted retina as a model to explore the immune response and expression of the immune modulator galectin-3 (Gal-3), induced by the cultivation per se and after additional immune stimulation with lipopolysaccharide (LPS), and how this correlates with retinal neurotoxicity. Methods Post-natal mouse retinas were cultured in a defined medium. One group was stimulated with LPS (100 ng/ml, 24 h). Retinal architecture, apoptotic cell death, and micro- and macroglial activity were studied at the time of cultivation (0 days in vitro (DIV)) and at 3, 4 and 7 DIV using morphological staining, biochemical- and immunohistochemical techniques. Results Our results show that sustained activation of macro- and microglia, characterized by no detectable cytokine release and limited expression of Gal-3, is not further inducing apoptosis additional to the axotomy-induced apoptosis in innermost nuclear layer. An elevated immune response was detected after LPS stimulation, as demonstrated primarily by release of immune mediators (i.e. interleukin 2 (IL-2), IL-6, KC/GRO (also known as CLCX1) and tumour necrosis factor-α (TNF-α)), increased numbers of microglia displaying morphologies of late activation stages as well as Gal-3 expression. This was accompanied with increased apoptosis in the two additional nuclear layers, and damage to retinal gross architecture. Conclusion We demonstrate that an immune response characterized by sustained and increased release of cytokines, along with an increase in Gal-3 expression, is accompanied by significant increased neurotoxicity in the explanted retina. Further investigations using the current setting may lead to increased understanding on the mechanisms involved in neuronal loss in retinal neurodegenerations.
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Affiliation(s)
- Patrik Maximilian Bauer
- Dept. of Biology, Sec. Functional Zoology, Lund University, Lund, Sweden
- Dept. Clinical Sciences in Lund, Div. Ophthalmology, Lund University, Lund, Sweden
| | - Marina Castro Zalis
- Dept. Clinical Sciences in Lund, Div. Ophthalmology, Lund University, Lund, Sweden
| | - Hodan Abdshill
- Dept. Clinical Sciences in Lund, Div. Ophthalmology, Lund University, Lund, Sweden
| | - Tomas Deierborg
- Dept. Experimental Medical Science, Experimental Neuroinflammation Laboratory, Lund University, Lund, Sweden
| | - Fredrik Johansson
- Dept. of Biology, Sec. Functional Zoology, Lund University, Lund, Sweden
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Kulkarni M, Trifunović D, Schubert T, Euler T, Paquet-Durand F. Calcium dynamics change in degenerating cone photoreceptors. Hum Mol Genet 2016; 25:3729-3740. [PMID: 27402880 DOI: 10.1093/hmg/ddw219] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 06/24/2016] [Accepted: 06/25/2016] [Indexed: 11/14/2022] Open
Abstract
Cone photoreceptors (cones) are essential for high-resolution daylight vision and colour perception. Loss of cones in hereditary retinal diseases has a dramatic impact on human vision. The mechanisms underlying cone death are poorly understood, and consequently, there are no treatments available. Previous studies suggest a central role for calcium (Ca2+) homeostasis deficits in photoreceptor degeneration; however, direct evidence for this is scarce and physiological measurements of Ca2+ in degenerating mammalian cones are lacking.Here, we took advantage of the transgenic HR2.1:TN-XL mouse line that expresses a genetically encoded Ca2+ biosensor exclusively in cones. We cross-bred this line with mouse models for primary ("cone photoreceptor function loss-1", cpfl1) and secondary ("retinal degeneration-1", rd1) cone degeneration, respectively, and assessed resting Ca2+ levels and light-evoked Ca2+ responses in cones using two-photon imaging. We found that Ca2+ dynamics were altered in cpfl1 cones, showing higher noise and variable Ca2+ levels, with significantly wider distribution than for wild-type and rd1 cones. Unexpectedly, up to 21% of cpfl1 cones still displayed light-evoked Ca2+ responses, which were larger and slower than wild-type responses. In contrast, genetically intact rd1 cones were characterized by lower noise and complete lack of visual function.Our study demonstrates alterations in cone Ca2+ dynamics in both primary and secondary cone degeneration. Our results are consistent with the view that higher (fluctuating) cone Ca2+ levels are involved in photoreceptor cell death in primary (cpfl1) but not in secondary (rd1) cone degeneration. These findings may guide the future development of therapies targeting photoreceptor Ca2+ homeostasis.
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Affiliation(s)
- Manoj Kulkarni
- Institute for Ophthalmic Research.,Werner Reichardt Centre for Integrative Neuroscience.,Graduate School of Cellular & Molecular Neuroscience
| | | | - Timm Schubert
- Institute for Ophthalmic Research.,Werner Reichardt Centre for Integrative Neuroscience
| | - Thomas Euler
- Institute for Ophthalmic Research (F.P-D.) (T.E.).,Werner Reichardt Centre for Integrative Neuroscience.,Bernstein Centre for Computational Neuroscience, University of Tübingen, Tübingen, Germany
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Jiao K, Sahaboglu A, Zrenner E, Ueffing M, Ekström PAR, Paquet-Durand F. Efficacy of PARP inhibition in Pde6a mutant mouse models for retinitis pigmentosa depends on the quality and composition of individual human mutations. Cell Death Discov 2016; 2:16040. [PMID: 27551530 PMCID: PMC4979439 DOI: 10.1038/cddiscovery.2016.40] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 04/28/2016] [Indexed: 11/09/2022] Open
Abstract
Retinitis pigmentosa (RP), an inherited blinding disease, is caused by a variety of different mutations that affect retinal photoreceptor function and survival. So far there is neither effective treatment nor cure. We have previously shown that poly(ADP-ribose)polymerase (PARP) acts as a common and critical denominator of cell death in photoreceptors, qualifying it as a potential target for future therapeutic intervention. A significant fraction of RP-causing mutations affect the genes for the rod photoreceptor phosphodiesterase 6A (PDE6A) subunit, but it is not known whether they all engage the same death pathway. Analysing three homozygous point mutations (Pde6a R562W, D670G, and V685M) and one compound heterozygous Pde6aV685M/R562W mutation in mouse models that match human RP patients, we demonstrate excessive activation of PARP, which correlated in time with the progression of photoreceptor degeneration. The causal involvement of PARP activity in the neurodegenerative process was confirmed in organotypic retinal explant cultures treated with the PARP-selective inhibitor PJ34, using different treatment time-points and durations. Remarkably, the neuroprotective efficacy of PARP inhibition correlated inversely with the strength of the genetically induced insult, with the D670G mutant showing the best treatment effects. Our results highlight PARP as a target for neuroprotective interventions in RP caused by PDE6A mutations and are a first attempt towards personalized, genotype-matched therapy development for RP. In addition, for each of the different mutant situations, our work identifies windows of opportunity for an optimal treatment regimen for further in vivo experimentation and possibly clinical studies.
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Affiliation(s)
- K Jiao
- Cell Death Mechanisms Group, Division of Experimental Ophthalmology, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Roentgenweg 11, Tuebingen 72076, Germany; Centre for Ophthalmology, The Second People's Hospital of Yunnan Province and The Fourth Affiliated Hospital of Kunming Medical University, Qingnian 176, Kunming 650021, China
| | - A Sahaboglu
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen , Tuebingen 72076, Germany
| | - E Zrenner
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen 72076, Germany; Werner Reichardt Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany
| | - M Ueffing
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen , Tuebingen 72076, Germany
| | - P A R Ekström
- Division of Ophthalmology, Department of Clinical Sciences, Lund, University of Lund , Lund 22184, Sweden
| | - F Paquet-Durand
- Cell Death Mechanisms Group, Division of Experimental Ophthalmology, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen , Roentgenweg 11, Tuebingen 72076, Germany
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66
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Understanding Cone Photoreceptor Cell Death in Achromatopsia. RETINAL DEGENERATIVE DISEASES 2016; 854:231-6. [DOI: 10.1007/978-3-319-17121-0_31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Adalimumab Reduces Photoreceptor Cell Death in A Mouse Model of Retinal Degeneration. Sci Rep 2015; 5:11764. [PMID: 26170250 PMCID: PMC4501000 DOI: 10.1038/srep11764] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/02/2015] [Indexed: 12/29/2022] Open
Abstract
Growing evidence suggests that inflammation is involved in the progression of retinitis pigmentosa (RP) both in patients and in animal models. The aim of this study was to investigate the effect of Adalimumab, a monoclonal anti-TNFα antibody, on retinal degeneration in a murine model of human autosomal recessive RP, the rd10 mice at postnatal day (P) 18. In our housing conditions, rd10 retinas were seriously damaged at P18. Adalimumab reduced photoreceptor cell death, as determined by scoring the number of TUNEL-positive cells. In addition, nuclear poly (ADP) ribose (PAR) content, an indirect measure of PAR polymerase (PARP) activity, was also reduced after treatment. The blockade of TNFα ameliorated reactive gliosis, as visualized by decreased GFAP and IBA1 immunolabelling (Müller cell and microglial markers, respectively) and decreased up-regulation of TNFα gene expression. Adalimumab also improved antioxidant response by restoring total antioxidant capacity and superoxide dismutase activity. Finally, we observed that Adalimumab normalized energetic and metabolic pattern in rd10 mouse retinas. Our study suggests that the TNFα blockade could be a successful therapeutic approach to increase photoreceptor survival during the progression of RP. Further studies are needed to characterize its effect along the progression of the disease.
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Sánchez-Vallejo V, Benlloch-Navarro S, López-Pedrajas R, Romero FJ, Miranda M. Neuroprotective actions of progesterone in an in vivo model of retinitis pigmentosa. Pharmacol Res 2015; 99:276-88. [PMID: 26158501 DOI: 10.1016/j.phrs.2015.06.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 11/27/2022]
Abstract
Progesterone has been shown to have neuroprotective effects in experimental acute brain injury models, but little is known about the effects of steroid sex hormones in models of retinitis pigmentosa (RP). The aim of this study was to asses whether progesterone had a protective effect in one animal model of RP (the rd1 mice), and whether its action was due at least in part, to its ability to reduce free radical damage or to increase antioxidant defences. Rd1 and wild type (wt) mice received an oral administration of 100 mg/kg body/weight of progesterone on alternate days starting at postnatal day 7 (PN7) and were sacrificed at different postnatal days. Our results show that progesterone decreases cell death, as the number of TUNEL-positive cells were decreased in the ONL of the retina from treated rd1 mice. At PN15, treatment with progesterone increased values of ERG b-wave amplitude (p<0,5) when compared with untreated mice. Progesterone also decreased the observed gliosis in RP, though this effect was transient. Treatment with progesterone significantly reduced retinal glutamate concentrations at PN15 and PN17. To clarify the mechanism by which progesterone is able to decrease retinal glutamate concentration, we examined expression levels of glutamine synthase (GS). Our results showed a significant increase in GS in rd1 treated retinas at PN13. Treatment with progesterone, significantly increase not only GSH but also oxidized glutathione retinal concentrations, probably because progesterone is able to partially increase glutamate cysteine ligase c subunit (GCLC) at PN15 and PN17 (p<0,05). In summary, our results demonstrate that oral administration of progesterone appears to act on multiple levels to delay photoreceptor death in this model of RP.
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Affiliation(s)
- V Sánchez-Vallejo
- Departamento de Ciencias Biomédicas, Instituto de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, Avda. Seminario s/n, 46113 Moncada, Valencia, Spain
| | - S Benlloch-Navarro
- Departamento de Ciencias Biomédicas, Instituto de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, Avda. Seminario s/n, 46113 Moncada, Valencia, Spain
| | - R López-Pedrajas
- Departamento de Ciencias Biomédicas, Instituto de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, Avda. Seminario s/n, 46113 Moncada, Valencia, Spain
| | - F J Romero
- Facultad de Medicina, Universidad Católica de Valencia 'San Vicente Mártir', Valencia, Spain
| | - M Miranda
- Departamento de Ciencias Biomédicas, Instituto de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, Avda. Seminario s/n, 46113 Moncada, Valencia, Spain.
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Ma H, Butler MR, Thapa A, Belcher J, Yang F, Baehr W, Biel M, Michalakis S, Ding XQ. cGMP/Protein Kinase G Signaling Suppresses Inositol 1,4,5-Trisphosphate Receptor Phosphorylation and Promotes Endoplasmic Reticulum Stress in Photoreceptors of Cyclic Nucleotide-gated Channel-deficient Mice. J Biol Chem 2015; 290:20880-20892. [PMID: 26124274 DOI: 10.1074/jbc.m115.641159] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 11/06/2022] Open
Abstract
Photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in phototransduction. Mutations in the cone CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. We have shown endoplasmic reticulum (ER) stress-associated apoptotic cone death and increased phosphorylation of the ER Ca(2+) channel inositol 1,4,5-trisphosphate receptor 1 (IP3R1) in CNG channel-deficient mice. We also presented a remarkable elevation of cGMP and an increased activity of the cGMP-dependent protein kinase (protein kinase G, PKG) in CNG channel deficiency. This work investigated whether cGMP/PKG signaling regulates ER stress and IP3R1 phosphorylation in CNG channel-deficient cones. Treatment with PKG inhibitor and deletion of guanylate cyclase-1 (GC1), the enzyme producing cGMP in cones, were used to suppress cGMP/PKG signaling in cone-dominant Cnga3(-/-)/Nrl(-/-) mice. We found that treatment with PKG inhibitor or deletion of GC1 effectively reduced apoptotic cone death, increased expression levels of cone proteins, and decreased activation of Müller glial cells. Furthermore, we observed significantly increased phosphorylation of IP3R1 and reduced ER stress. Our findings demonstrate a role of cGMP/PKG signaling in ER stress and ER Ca(2+) channel regulation and provide insights into the mechanism of cone degeneration in CNG channel deficiency.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Arjun Thapa
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Josh Belcher
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Wolfgang Baehr
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
| | - Martin Biel
- Center for Integrated Protein Science Munich and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
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70
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Inhibition of dopamine signaling suppresses cGMP accumulation in rd1 retinal organ cultures. Neuroreport 2015; 25:601-6. [PMID: 24614363 DOI: 10.1097/wnr.0000000000000145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The rd1 mouse is a model of retinitis pigmentosa, an inherited photoreceptor neurodegenerative disease. In rd1 retina, early onset rod degeneration is caused by a Pde6b mutation that leads to high levels of intracellular cyclic guanosine monophosphate (cGMP). Cyclic nucleotide-gated ion channels (CNGCs), necessary for phototransduction, are regulated by cGMP. We have previously demonstrated that inhibition of dopamine signaling blocks rd1 photoreceptor degeneration in retinal organ cultures. The mechanism underlying this protection remains unknown. The aim of this study was to determine whether inhibition of dopamine signaling alters cGMP accumulation or CNGC expression. Dopamine depletion from rd1 retinal organ cultures resulted in a significant decrease in cGMP compared with untreated rd1 organ cultures. However, cGMP levels in both treated and untreated rd1 organ cultures significantly exceeded cGMP levels in wild-type (wt) retinal organ cultures. The CNGC expression profile was first determined in vivo. Both channel subunits, Cnga1 and Cngb1, are expressed at low levels by postnatal day 2 (P2), increasing sharply by P6 with a modest increase after P12 in wt retina. A similar pattern is seen in rd1 retina until P12 when expression levels decrease, leading to cell death. No significant difference was observed in the expression of either Cnga1 or Cngb1 in organ cultures from wt, rd1, and dopamine-depleted rd1 retinas. Our results show that dopamine depletion significantly decreases cGMP levels in rd1 retinal organ cultures, but that cGMP accumulation remains high, requiring additional mechanisms for photoreceptor protection. These mechanisms may include activation of protein kinase G-signaling pathways and/or crosstalk with dopamine signaling through cyclic adenosine monophosphate pathways.
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71
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Farinelli P, Perera A, Arango-Gonzalez B, Trifunovic D, Wagner M, Carell T, Biel M, Zrenner E, Michalakis S, Paquet-Durand F, Ekström PAR. DNA methylation and differential gene regulation in photoreceptor cell death. Cell Death Dis 2014; 5:e1558. [PMID: 25476906 PMCID: PMC4649831 DOI: 10.1038/cddis.2014.512] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 01/09/2023]
Abstract
Retinitis pigmentosa (RP) defines a group of inherited degenerative retinal diseases causing progressive loss of photoreceptors. To this day, RP is still untreatable and rational treatment development will require a thorough understanding of the underlying cell death mechanisms. Methylation of the DNA base cytosine by DNA methyltransferases (DNMTs) is an important epigenetic factor regulating gene expression, cell differentiation, cell death, and survival. Previous studies suggested an involvement of epigenetic mechanisms in RP, and in this study, increased cytosine methylation was detected in dying photoreceptors in the rd1, rd2, P23H, and S334ter rodent models for RP. Ultrastructural analysis of photoreceptor nuclear morphology in the rd1 mouse model for RP revealed a severely altered chromatin structure during retinal degeneration that coincided with an increased expression of the DNMT isozyme DNMT3a. To identify disease-specific differentially methylated DNA regions (DMRs) on a genomic level, we immunoprecipitated methylated DNA fragments and subsequently analyzed them with a targeted microarray. Genome-wide comparison of DMRs between rd1 and wild-type retina revealed hypermethylation of genes involved in cell death and survival as well as cell morphology and nervous system development. When correlating DMRs with gene expression data, we found that hypermethylation occurred alongside transcriptional repression. Consistently, motif analysis showed that binding sites of several important transcription factors for retinal physiology were hypermethylated in the mutant model, which also correlated with transcriptional silencing of their respective target genes. Finally, inhibition of DNMTs in rd1 organotypic retinal explants using decitabine resulted in a substantial reduction of photoreceptor cell death, suggesting inhibition of DNA methylation as a potential novel treatment in RP.
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Affiliation(s)
- P Farinelli
- 1] Division of Ophthalmology, Department of Clinical Sciences, University of Lund, BMC-B11, Lund 22184, Sweden [2] Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany
| | - A Perera
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany
| | - B Arango-Gonzalez
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany
| | - D Trifunovic
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany
| | - M Wagner
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, Ludwig-Maximilians-Universität München, Munich 81377, Germany
| | - T Carell
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, Ludwig-Maximilians-Universität München, Munich 81377, Germany
| | - M Biel
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany
| | - E Zrenner
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany
| | - S Michalakis
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich 81377, Germany
| | - F Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen 72076, Germany
| | - P A R Ekström
- Division of Ophthalmology, Department of Clinical Sciences, University of Lund, BMC-B11, Lund 22184, Sweden
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72
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Arango-Gonzalez B, Trifunović D, Sahaboglu A, Kranz K, Michalakis S, Farinelli P, Koch S, Koch F, Cottet S, Janssen-Bienhold U, Dedek K, Biel M, Zrenner E, Euler T, Ekström P, Ueffing M, Paquet-Durand F. Identification of a common non-apoptotic cell death mechanism in hereditary retinal degeneration. PLoS One 2014; 9:e112142. [PMID: 25392995 PMCID: PMC4230983 DOI: 10.1371/journal.pone.0112142] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 10/13/2014] [Indexed: 01/10/2023] Open
Abstract
Cell death in neurodegenerative diseases is often thought to be governed by apoptosis; however, an increasing body of evidence suggests the involvement of alternative cell death mechanisms in neuronal degeneration. We studied retinal neurodegeneration using 10 different animal models, covering all major groups of hereditary human blindness (rd1, rd2, rd10, Cngb1 KO, Rho KO, S334ter, P23H, Cnga3 KO, cpfl1, Rpe65 KO), by investigating metabolic processes relevant for different forms of cell death. We show that apoptosis plays only a minor role in the inherited forms of retinal neurodegeneration studied, where instead, a non-apoptotic degenerative mechanism common to all mutants is of major importance. Hallmark features of this pathway are activation of histone deacetylase, poly-ADP-ribose-polymerase, and calpain, as well as accumulation of cyclic guanosine monophosphate and poly-ADP-ribose. Our work thus demonstrates the prevalence of alternative cell death mechanisms in inherited retinal degeneration and provides a rational basis for the design of mutation-independent treatments.
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Affiliation(s)
| | - Dragana Trifunović
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Ayse Sahaboglu
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Katharina Kranz
- Department of Neurobiology, University of Oldenburg, Oldenburg, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Pietro Farinelli
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Division of Ophthalmology, Department of Clinical Sciences, University of Lund, Lund, Sweden
| | - Susanne Koch
- Center for Integrated Protein Science Munich and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Fred Koch
- Center for Integrated Protein Science Munich and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Sandra Cottet
- Institute for Research in Ophthalmology, Sion, Switzerland
| | | | - Karin Dedek
- Department of Neurobiology, University of Oldenburg, Oldenburg, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Eberhart Zrenner
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Centre for Integrative Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Thomas Euler
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
- Centre for Integrative Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Per Ekström
- Division of Ophthalmology, Department of Clinical Sciences, University of Lund, Lund, Sweden
| | - Marius Ueffing
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
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Paquet-Durand F, Sahaboglu A, Dietter J, Paquet-Durand O, Hitzmann B, Ueffing M, Ekström PAR. How long does a photoreceptor cell take to die? Implications for the causative cell death mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:575-81. [PMID: 24664746 DOI: 10.1007/978-1-4614-3209-8_73] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The duration of cell death may allow deducing the underlying degenerative mechanism. To find out how long a photoreceptor takes to die, we used the rd1 mouse model for retinal neurodegeneration, which is characterized by phosphodiesterase-6 (PDE6) dysfunction and photoreceptor death triggered by high cGMP levels. Based on cellular data on the progression of cGMP accumulation, cell death, and survival, we created a mathematical model to simulate the temporal development of the degeneration and the clearance of dead cells. Both cellular data and modelling suggested that at the level of the individual cell, the degenerative process was rather slow, taking around 80 h to complete. Organotypic retinal explant cultures derived from wild-type animals and exposed to the selective PDE6 inhibitor zaprinast, confirmed the surprisingly long duration of an individual photoreceptor cell's death. We briefly discuss the possibility to link different cell death stages and their temporal progression to specific enzymatic activities known to be causally connected to cell death. This in turn opens up new perspectives for the treatment of inherited retinal degeneration, both in terms of therapeutic targets and temporal windows-of-opportunity.
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Affiliation(s)
- F Paquet-Durand
- François Paquet-Durand, Institute for Ophthalmic Research, University of Tübingen, Röntgenweg 11, 72076, Tübingen, Germany,
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74
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Knockout of PARG110 confers resistance to cGMP-induced toxicity in mammalian photoreceptors. Cell Death Dis 2014; 5:e1234. [PMID: 24853412 PMCID: PMC4047865 DOI: 10.1038/cddis.2014.208] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 03/20/2014] [Accepted: 04/09/2014] [Indexed: 11/08/2022]
Abstract
Hereditary retinal degeneration (RD) relates to a heterogeneous group of blinding human diseases in which the light sensitive neurons of the retina, the photoreceptors, die. RD is currently untreatable and the underlying cellular mechanisms remain poorly understood. However, the activity of the enzyme poly-ADP-ribose polymerase-1 (PARP1) and excessive generation of poly-ADP-ribose (PAR) polymers in photoreceptor nuclei have been shown to be causally involved in RD. The activity of PARP1 is to a large extent governed by its functional antagonist, poly-ADP-glycohydrolase (PARG), which thus also may have a role in RD. To investigate this, we analyzed PARG expression in the retina of wild-type (wt) mice and in the rd1 mouse model for human RD, and detected increased PARG protein in a subset of degenerating rd1 photoreceptors. Knockout (KO) animals lacking the 110 kDa nuclear PARG isoform were furthermore analyzed, and their retinal morphology and function were indistinguishable from wild-type animals. Organotypic wt retinal explants can be experimentally treated to induce rd1-like photoreceptor death, but PARG110 KO retinal explants were unexpectedly highly resistant to such treatment. The resistance was associated with decreased PAR accumulation and low PARP activity, indicating that PARG110 may positively regulate PARP1, an event that therefore is absent in PARG110 KO tissue. Our study demonstrates a causal involvement of PARG110 in the process of photoreceptor degeneration. Contrasting its anticipated role as a functional antagonist, absence of PARG110 correlated with low PARP activity, suggesting that PARG110 and PARP1 act in a positive feedback loop, which is especially active under pathologic conditions. This in turn highlights both PARG110 and PARP1 as potential targets for neuroprotective treatments for RD.
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75
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The nitric oxide-cGKII system relays death and survival signals during embryonic retinal development via AKT-induced CREB1 activation. Cell Death Differ 2014; 21:915-28. [PMID: 24531539 DOI: 10.1038/cdd.2014.11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 12/21/2013] [Accepted: 01/08/2014] [Indexed: 01/28/2023] Open
Abstract
During early neurogenesis, retinal neuronal cells display a conserved differentiation program in vertebrates. Previous studies established that nitric oxide (NO) and cGMP accumulation regulate essential events in retinal physiology. Here we used pharmacological and genetic loss-of-function to investigate the effects of NO and its downstream signaling pathway in the survival of developing avian retinal neurons in vitro and in vivo. Six-day-old (E6) chick retinal cells displayed increased calcium influx and produced higher amounts of NO when compared with E8 cells. L-arginine (substrate for NO biosynthesis) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP; a nitrosothiol NO donor) promoted extensive cell death in E6 retinas, whereas in E8 both substances decreased apoptosis. The effect of NO at both periods was mediated by soluble guanylyl cyclase (sGC) and cGMP-dependent kinase (cGK) activation. In addition, shRNA-mediated cGKII knockdown prevented NO-induced cell death (E6) and cell survival (E8). This, NO-induced cell death or cell survival was not correlated with an early inhibition of retinal cell proliferation. E6 cells also responded differentially from E8 neurons regarding cyclic AMP-responsive element-binding protein (CREB) activation in the retina in vivo. NO strongly decreased nuclear phospho-CREB staining in E6 but it robustly enhanced CREB phosphorylation in the nuclei of E8 neurons, an effect that was completely abrogated by cGKII shRNAs at both embryonic stages. The ability of NO in regulating CREB differentially during retinal development relied on the capacity of cGKII in decreasing (E6) or increasing (E8) nuclear AKT (V-Akt murine thymoma viral oncogene) activation. Accordingly, inhibiting AKT prevented both cGKII shRNA-mediated CREB upregulation in E6 and SNAP-induced CREB activation in E8. Furthermore, shRNA-mediated in vivo cGKII or in vitro CREB1 knockdown confirmed that NO/cGKII dualistically regulated the downstream CREB1 pathway and caspase activation in the chick retina to modulate neuronal viability. These data demonstrate that NO-mediated cGKII signaling may function to control the viability of neuronal cells during early retinal development via AKT/CREB1 activity.
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76
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Viringipurampeer IA, Shan X, Gregory-Evans K, Zhang JP, Mohammadi Z, Gregory-Evans CY. Rip3 knockdown rescues photoreceptor cell death in blind pde6c zebrafish. Cell Death Differ 2014; 21:665-75. [PMID: 24413151 DOI: 10.1038/cdd.2013.191] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/15/2013] [Accepted: 11/22/2013] [Indexed: 01/03/2023] Open
Abstract
Achromatopsia is a progressive autosomal recessive retinal disease characterized by early loss of cone photoreceptors and later rod photoreceptor loss. In most cases, mutations have been identified in CNGA3, CNGB3, GNAT2, PDE6C or PDE6H genes. Owing to this genetic heterogeneity, mutation-independent therapeutic schemes aimed at preventing cone cell death are very attractive treatment strategies. In pde6c(w59) mutant zebrafish, cone photoreceptors expressed high levels of receptor-interacting protein kinase 1 (RIP1) and receptor-interacting protein kinase 3 (RIP3) kinases, key regulators of necroptotic cell death. In contrast, rod photoreceptor cells were alternatively immunopositive for caspase-3 indicating activation of caspase-dependent apoptosis in these cells. Morpholino gene knockdown of rip3 in pde6c(w59) embryos rescued the dying cone photoreceptors by inhibiting the formation of reactive oxygen species and by inhibiting second-order neuron remodelling in the inner retina. In rip3 morphant larvae, visual function was restored in the cones by upregulation of the rod phosphodiesterase genes (pde6a and pde6b), compensating for the lack of cone pde6c suggesting that cones are able to adapt to their local environment. Furthermore, we demonstrated through pharmacological inhibition of RIP1 and RIP3 activity that cone cell death was also delayed. Collectively, these results demonstrate that the underlying mechanism of cone cell death in the pde6c(w59) mutant retina is through necroptosis, whereas rod photoreceptor bystander death occurs through a caspase-dependent mechanism. This suggests that targeting the RIP kinase signalling pathway could be an effective therapeutic intervention in retinal degeneration patients. As bystander cell death is an important feature of many retinal diseases, combinatorial approaches targeting different cell death pathways may evolve as an important general principle in treatment.
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Affiliation(s)
- I A Viringipurampeer
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
| | - X Shan
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
| | - K Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
| | - J P Zhang
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
| | - Z Mohammadi
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
| | - C Y Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 3N9, Canada
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cGMP accumulation causes photoreceptor degeneration in CNG channel deficiency: evidence of cGMP cytotoxicity independently of enhanced CNG channel function. J Neurosci 2013; 33:14939-48. [PMID: 24027293 DOI: 10.1523/jneurosci.0909-13.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Photoreceptor cyclic nucleotide-gated (CNG) channels regulate Ca(2+) influx in rod and cone photoreceptors. cGMP, the native ligand of the photoreceptor CNG channels, has been associated with cytotoxicity when its levels rise above normal due to defects in photoreceptor phosphodiesterase (PDE6) or regulation of retinal guanylyl cyclase (retGC). We found a massive accumulation of cGMP in CNGA3-deficient retina and investigated whether cGMP accumulation plays a role in cone degeneration in CNG channel deficiency. The time course study showed that the retinal cGMP level in Cnga3(-/-);Nrl(-/-) mice with CNGA3 deficiency on a cone-dominant background was sharply increased at postnatal day 8 (P8), peaked around P10-P15, remained high through P30-P60, and returned to near control level at P90. This elevation pattern correlated with photoreceptor apoptotic death, which peaked around P15-P20. In Cnga3(-/-);Gucy2e(-/-) mice lacking retGC1, cone density and expression levels of cone-specific proteins were significantly increased compared with Cnga3(-/-), consistent with a role of cGMP accumulation as the major contributor to cone death caused by CNG channel deficiency. The activity and expression levels of cGMP-dependent protein kinase G (PKG) were significantly increased in Cnga3(-/-);Nrl(-/-) retina compared with Nrl(-/-), suggesting an involvement of PKG regulation in cell death. Our results indicate that cGMP accumulation in photoreceptors can itself exert cytotoxic effect in cones, independently of CNG channel activity and Ca(2+) influx.
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78
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Martínez-Fernández de la Cámara C, Sequedo MD, Gómez-Pinedo U, Jaijo T, Aller E, García-Tárraga P, García-Verdugo JM, Millán JM, Rodrigo R. Phosphodiesterase inhibition induces retinal degeneration, oxidative stress and inflammation in cone-enriched cultures of porcine retina. Exp Eye Res 2013; 111:122-33. [PMID: 23578797 DOI: 10.1016/j.exer.2013.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
Abstract
Inherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the phototransduction and, mutations in genes related to its metabolism are responsible for different retinal dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4-5% of the retinitis pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether pharmacological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, thus replacing or reducing animal experiments.
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79
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Kranz K, Paquet-Durand F, Weiler R, Janssen-Bienhold U, Dedek K. Testing for a gap junction-mediated bystander effect in retinitis pigmentosa: secondary cone death is not altered by deletion of connexin36 from cones. PLoS One 2013; 8:e57163. [PMID: 23468924 PMCID: PMC3584123 DOI: 10.1371/journal.pone.0057163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/18/2013] [Indexed: 11/23/2022] Open
Abstract
Retinitis pigmentosa (RP) relates to a group of hereditary neurodegenerative diseases of the retina. On the cellular level, RP results in the primary death of rod photoreceptors, caused by rod-specific mutations, followed by a secondary degeneration of genetically normal cones. Different mechanisms may influence the spread of cell death from one photoreceptor type to the other. As one of these mechanisms a gap junction-mediated bystander effect was proposed, i.e., toxic molecules generated in dying rods and propagating through gap junctions induce the death of healthy cone photoreceptors. We investigated whether disruption of rod-cone coupling can prevent secondary cone death and reduce the spread of degeneration. We tested this hypothesis in two different mouse models for retinal degeneration (rhodopsin knockout and rd1) by crossbreeding them with connexin36-deficient mice as connexin36 represents the gap junction protein on the cone side and lack thereof most likely disrupts rod-cone coupling. Using immunohistochemistry, we compared the progress of cone degeneration between connexin36-deficient mouse mutants and their connexin36-expressing littermates at different ages and assessed the accompanied morphological changes during the onset (rhodopsin knockout) and later stages of secondary cone death (rd1 mutants). Connexin36-deficient mouse mutants showed the same time course of cone degeneration and the same morphological changes in second order neurons as their connexin36-expressing littermates. Thus, our results indicate that disruption of connexin36-mediated rod-cone coupling does not stop, delay or spatially restrict secondary cone degeneration and suggest that the gap junction-mediated bystander effect does not contribute to the progression of RP.
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Affiliation(s)
- Katharina Kranz
- Department of Neurobiology, University of Oldenburg, Oldenburg, Germany.
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80
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Sahaboglu A, Paquet-Durand O, Dietter J, Dengler K, Bernhard-Kurz S, Ekström PAR, Hitzmann B, Ueffing M, Paquet-Durand F. Retinitis pigmentosa: rapid neurodegeneration is governed by slow cell death mechanisms. Cell Death Dis 2013; 4:e488. [PMID: 23392176 PMCID: PMC3593146 DOI: 10.1038/cddis.2013.12] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/21/2012] [Accepted: 01/03/2013] [Indexed: 12/31/2022]
Abstract
For most neurodegenerative diseases the precise duration of an individual cell's death is unknown, which is an obstacle when counteractive measures are being considered. To address this, we used the rd1 mouse model for retinal neurodegeneration, characterized by phosphodiesterase-6 (PDE6) dysfunction and photoreceptor death triggered by high cyclic guanosine-mono-phosphate (cGMP) levels. Using cellular data on cGMP accumulation, cell death, and survival, we created mathematical models to simulate the temporal development of the degeneration. We validated model predictions using organotypic retinal explant cultures derived from wild-type animals and exposed to the selective PDE6 inhibitor zaprinast. Together, photoreceptor data and modeling for the first time delineated three major cell death phases in a complex neuronal tissue: (1) initiation, taking up to 36 h, (2) execution, lasting another 40 h, and finally (3) clearance, lasting about 7 h. Surprisingly, photoreceptor neurodegeneration was noticeably slower than necrosis or apoptosis, suggesting a different mechanism of death for these neurons.
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Affiliation(s)
- A Sahaboglu
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - O Paquet-Durand
- Institute of Food Science and Biotechnology, University of Stuttgart Hohenheim, Stuttgart, Germany
| | - J Dietter
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - K Dengler
- Skin Clinic, University of Tübingen, Tübingen, Germany
| | - S Bernhard-Kurz
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - P AR Ekström
- Department of Clinical Sciences, Lund, University of Lund, Lund, Sweden
| | - B Hitzmann
- Institute of Food Science and Biotechnology, University of Stuttgart Hohenheim, Stuttgart, Germany
| | - M Ueffing
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - F Paquet-Durand
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
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81
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Abstract
Cyclic guanosine 3'-5'-monophosphate (cGMP) plays a key role in the physiological process of light detection in photoreceptor cells of the retina. However, there is also growing evidence that cGMP may be critically involved in some pathophysiological processes of the retina since degenerating photoreceptors in mouse models of retinitis pigmentosa and achromatopsia accumulate high levels of cGMP. Here, we describe methods that allow the detection, subcellular localization, and quantification of cGMP in the retina and propose that cGMP accumulation can be used as a biomarker for photoreceptor degeneration.
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82
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Dickison VM, Richmond AM, Abu Irqeba A, Martak JG, Hoge SCE, Brooks MJ, Othman MI, Khanna R, Mears AJ, Chowdhury AY, Swaroop A, Ogilvie JM. A role for prenylated rab acceptor 1 in vertebrate photoreceptor development. BMC Neurosci 2012; 13:152. [PMID: 23241222 PMCID: PMC3576285 DOI: 10.1186/1471-2202-13-152] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 11/19/2012] [Indexed: 11/10/2022] Open
Abstract
Background The rd1 mouse retina is a well-studied model of retinal degeneration where rod photoreceptors undergo cell death beginning at postnatal day (P) 10 until P21. This period coincides with photoreceptor terminal differentiation in a normal retina. We have used the rd1 retina as a model to investigate early molecular defects in developing rod photoreceptors prior to the onset of degeneration. Results Using a microarray approach, we performed gene profiling comparing rd1 and wild type (wt) retinas at four time points starting at P2, prior to any obvious biochemical or morphological differences, and concluding at P8, prior to the initiation of cell death. Of the 143 identified differentially expressed genes, we focused on Rab acceptor 1 (Rabac1), which codes for the protein Prenylated rab acceptor 1 (PRA1) and plays an important role in vesicular trafficking. Quantitative RT-PCR analysis confirmed reduced expression of PRA1 in rd1 retina at all time points examined. Immunohistochemical observation showed that PRA1-like immunoreactivity (LIR) co-localized with the cis-Golgi marker GM-130 in the photoreceptor as the Golgi translocated from the perikarya to the inner segment during photoreceptor differentiation in wt retinas. Diffuse PRA1-LIR, distinct from the Golgi marker, was seen in the distal inner segment of wt photoreceptors starting at P8. Both plexiform layers contained PRA1 positive punctae independent of GM-130 staining during postnatal development. In the inner retina, PRA1-LIR also colocalized with the Golgi marker in the perinuclear region of most cells. A similar pattern was seen in the rd1 mouse inner retina. However, punctate and significantly reduced PRA1-LIR was present throughout the developing rd1 inner segment, consistent with delayed photoreceptor development and abnormalities in Golgi sorting and vesicular trafficking. Conclusions We have identified genes that are differentially regulated in the rd1 retina at early time points, which may give insights into developmental defects that precede photoreceptor cell death. This is the first report of PRA1 expression in the retina. Our data support the hypothesis that PRA1 plays an important role in vesicular trafficking between the Golgi and cilia in differentiating and mature rod photoreceptors.
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83
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Sancho-Pelluz J, Paquet-Durand F. HDAC inhibition prevents Rd1 mouse photoreceptor degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:107-13. [PMID: 22183322 DOI: 10.1007/978-1-4614-0631-0_15] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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84
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Mok CA, Healey MP, Shekhar T, Leroux MR, Héon E, Zhen M. Mutations in a guanylate cyclase GCY-35/GCY-36 modify Bardet-Biedl syndrome-associated phenotypes in Caenorhabditis elegans. PLoS Genet 2011; 7:e1002335. [PMID: 22022287 PMCID: PMC3192831 DOI: 10.1371/journal.pgen.1002335] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/25/2011] [Indexed: 11/23/2022] Open
Abstract
Ciliopathies are pleiotropic and genetically heterogeneous disorders caused by defective development and function of the primary cilium. Bardet-Biedl syndrome (BBS) proteins localize to the base of cilia and undergo intraflagellar transport, and the loss of their functions leads to a multisystemic ciliopathy. Here we report the identification of mutations in guanylate cyclases (GCYs) as modifiers of Caenorhabditis elegans bbs endophenotypes. The loss of GCY-35 or GCY-36 results in suppression of the small body size, developmental delay, and exploration defects exhibited by multiple bbs mutants. Moreover, an effector of cGMP signalling, a cGMP-dependent protein kinase, EGL-4, also modifies bbs mutant defects. We propose that a misregulation of cGMP signalling, which underlies developmental and some behavioural defects of C. elegans bbs mutants, may also contribute to some BBS features in other organisms. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, multisystemic disorder. Defects to the cilium, an evolutionarily conserved organelle, cause ciliopathies, a growing class of diseases that includes BBS. BBS proteins are involved in the vesicular transport of proteins to the cilium and in the process of intraflagellar transport. Here we show that, in addition to sensory defects, Caenorhabditis elegans bbs mutants exhibit reduced body size and delayed developmental timing. The reduced body size phenotype is not fully recapitulated by IFT mutants, suggesting that BBS proteins may have additional functions beyond bridging IFT motors. We further identified that the loss of function mutations in the soluble guanylate cyclase complex, GCY-35/GCY-36, results in a suppression of these defects. Interestingly, GCY-35/GCY-36 influences the body size through a cGMP-dependent protein kinase EGL-4 in a group of body cavity neurons. BBS proteins, on the other hand, function through a non-overlapping set of ciliated sensory neurons to influence cGMP signalling in the body cavity neurons. In conclusion, this study reveals a non-cell autonomous role for sensory cilia in regulating cGMP signalling during development. We propose that aberrant cGMP signalling, essential for a number of cellular processes, may also contribute to some ciliopathy features in other systems.
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Affiliation(s)
- Calvin A. Mok
- The Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Michael P. Healey
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Tanvi Shekhar
- The Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Michel R. Leroux
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Elise Héon
- The Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- * E-mail: (MZ); (HZ)
| | - Mei Zhen
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- * E-mail: (MZ); (HZ)
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85
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Sancho-Pelluz J, Alavi MV, Sahaboglu A, Kustermann S, Farinelli P, Azadi S, van Veen T, Romero FJ, Paquet-Durand F, Ekström P. Excessive HDAC activation is critical for neurodegeneration in the rd1 mouse. Cell Death Dis 2011; 1:e24. [PMID: 21364632 PMCID: PMC3032332 DOI: 10.1038/cddis.2010.4] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inherited retinal degenerations, collectively termed retinitis pigmentosa (RP), constitute one of the leading causes of blindness in the developed world. RP is at present untreatable and the underlying neurodegenerative mechanisms are unknown, even though the genetic causes are often established. Acetylation and deacetylation of histones, carried out by histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively, affects cellular division, differentiation, death and survival. We found acetylation of histones and probably other proteins to be dramatically reduced in degenerating photoreceptors in the rd1 human homologous mouse model for RP. Using a custom developed in situ HDAC activity assay, we show that overactivation of HDAC classes I/II temporally precedes photoreceptor degeneration. Moreover, pharmacological inhibition of HDACs I/II activity in rd1 organotypic retinal explants decreased activity of poly-ADP-ribose-polymerase and strongly reduced photoreceptor cell death. These findings highlight the importance of protein acetylation for photoreceptor cell death and survival and propose certain HDAC classes as novel targets for the pharmacological intervention in RP.
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Affiliation(s)
- J Sancho-Pelluz
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
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86
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Kaur J, Mencl S, Sahaboglu A, Farinelli P, van Veen T, Zrenner E, Ekström P, Paquet-Durand F, Arango-Gonzalez B. Calpain and PARP activation during photoreceptor cell death in P23H and S334ter rhodopsin mutant rats. PLoS One 2011; 6:e22181. [PMID: 21765948 PMCID: PMC3134478 DOI: 10.1371/journal.pone.0022181] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 06/20/2011] [Indexed: 11/18/2022] Open
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of inherited neurodegenerative diseases affecting photoreceptors and causing blindness. Many human cases are caused by mutations in the rhodopsin gene. An important question regarding RP pathology is whether different genetic defects trigger the same or different cell death mechanisms. To answer this question, we analysed photoreceptor degeneration in P23H and S334ter transgenic rats carrying rhodopsin mutations that affect protein folding and sorting respectively. We found strong activation of calpain and poly(ADP-ribose) polymerase (PARP) in both mutants, concomitant with calpastatin down-regulation, increased oxidative DNA damage and accumulation of PAR polymers. These parameters were strictly correlated with the temporal progression of photoreceptor degeneration, mirroring earlier findings in the phosphodiesterase-6 mutant rd1 mouse, and suggesting execution of non-apoptotic cell death mechanisms. Interestingly, activation of caspases-3 and -9 and cytochrome c leakage-key events in apoptotic cell death--were observed only in the S334ter mutant, which also showed increased expression of PARP-1. The identification of the same metabolic markers triggered by different mutations in two different species suggests the existence of common cell death mechanisms, which is a major consideration for any mutation independent treatment.
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Affiliation(s)
- Jasvir Kaur
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Stine Mencl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ayse Sahaboglu
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Pietro Farinelli
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology, Clinical Sciences Lund, University of Lund, Lund, Sweden
| | - Theo van Veen
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology, Clinical Sciences Lund, University of Lund, Lund, Sweden
| | - Eberhart Zrenner
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Per Ekström
- Department of Ophthalmology, Clinical Sciences Lund, University of Lund, Lund, Sweden
| | - François Paquet-Durand
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Blanca Arango-Gonzalez
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- * E-mail:
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87
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Paquet-Durand F, Beck S, Michalakis S, Goldmann T, Huber G, Mühlfriedel R, Trifunović D, Fischer MD, Fahl E, Duetsch G, Becirovic E, Wolfrum U, van Veen T, Biel M, Tanimoto N, Seeliger MW. A key role for cyclic nucleotide gated (CNG) channels in cGMP-related retinitis pigmentosa. Hum Mol Genet 2010; 20:941-7. [PMID: 21149284 DOI: 10.1093/hmg/ddq539] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rd1 natural mutant is one of the first and probably the most commonly studied mouse model for retinitis pigmentosa (RP), a severe and frequently blinding human retinal degeneration. In several decades of research, the link between the increase in photoreceptor cGMP levels and the extremely rapid cell death gave rise to a number of hypotheses. Here, we provide clear evidence that the presence of cyclic nucleotide gated (CNG) channels in the outer segment membrane is the key to rod photoreceptor loss. In Cngb1(-/-) × rd1 double mutants devoid of regular CNG channels, cGMP levels are still pathologically high, but rod photoreceptor viability and outer segment morphology are greatly improved. Importantly, cone photoreceptors, the basis for high-resolution daylight and colour vision, survived and remained functional for extended periods of time. These findings strongly support the hypothesis of deleterious calcium (Ca(2+))-influx as the cause of rapid rod cell death and highlight the importance of CNG channels in this process. Furthermore, our findings suggest that targeting rod CNG channels, rather than general Ca(2+)-channel blockade, is a most promising symptomatic approach to treat otherwise incurable forms of cGMP-related RP.
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Affiliation(s)
- François Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Röntgenweg 11, 72076 Tübingen, Germany.
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88
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Francis SH, Busch JL, Corbin JD, Sibley D. cGMP-dependent protein kinases and cGMP phosphodiesterases in nitric oxide and cGMP action. Pharmacol Rev 2010; 62:525-63. [PMID: 20716671 DOI: 10.1124/pr.110.002907] [Citation(s) in RCA: 695] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
To date, studies suggest that biological signaling by nitric oxide (NO) is primarily mediated by cGMP, which is synthesized by NO-activated guanylyl cyclases and broken down by cyclic nucleotide phosphodiesterases (PDEs). Effects of cGMP occur through three main groups of cellular targets: cGMP-dependent protein kinases (PKGs), cGMP-gated cation channels, and PDEs. cGMP binding activates PKG, which phosphorylates serines and threonines on many cellular proteins, frequently resulting in changes in activity or function, subcellular localization, or regulatory features. The proteins that are so modified by PKG commonly regulate calcium homeostasis, calcium sensitivity of cellular proteins, platelet activation and adhesion, smooth muscle contraction, cardiac function, gene expression, feedback of the NO-signaling pathway, and other processes. Current therapies that have successfully targeted the NO-signaling pathway include nitrovasodilators (nitroglycerin), PDE5 inhibitors [sildenafil (Viagra and Revatio), vardenafil (Levitra), and tadalafil (Cialis and Adcirca)] for treatment of a number of vascular diseases including angina pectoris, erectile dysfunction, and pulmonary hypertension; the PDE3 inhibitors [cilostazol (Pletal) and milrinone (Primacor)] are used for treatment of intermittent claudication and acute heart failure, respectively. Potential for use of these medications in the treatment of other maladies continues to emerge.
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Affiliation(s)
- Sharron H Francis
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN 37232-0615, USA.
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89
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Sahaboglu A, Tanimoto N, Kaur J, Sancho-Pelluz J, Huber G, Fahl E, Arango-Gonzalez B, Zrenner E, Ekström P, Löwenheim H, Seeliger M, Paquet-Durand F. PARP1 gene knock-out increases resistance to retinal degeneration without affecting retinal function. PLoS One 2010; 5:e15495. [PMID: 21124852 PMCID: PMC2990765 DOI: 10.1371/journal.pone.0015495] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 10/03/2010] [Indexed: 11/25/2022] Open
Abstract
Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases affecting photoreceptors and causing blindness in humans. Previously, excessive activation of enzymes belonging to the poly-ADP-ribose polymerase (PARP) group was shown to be involved in photoreceptor degeneration in the human homologous rd1 mouse model for RP. Since there are at least 16 different PARP isoforms, we investigated the exact relevance of the predominant isoform - PARP1 - for photoreceptor cell death using PARP1 knock-out (KO) mice. In vivo and ex vivo morphological analysis using optic coherence tomography (OCT) and conventional histology revealed no major alterations of retinal phenotype when compared to wild-type (wt). Likewise, retinal function as assessed by electroretinography (ERG) was normal in PARP1 KO animals. We then used retinal explant cultures derived from wt, rd1, and PARP1 KO animals to test their susceptibility to chemically induced photoreceptor degeneration. Since photoreceptor degeneration in the rd1 retina is triggered by a loss-of-function in phosphodiesterase-6 (PDE6), we used selective PDE6 inhibition to emulate the rd1 situation on non-rd1 genotypes. While wt retina subjected to PDE6 inhibition showed massive photoreceptor degeneration comparable to rd1 retina, in the PARP1 KO situation, cell death was robustly reduced. Together, these findings demonstrate that PARP1 activity is in principle dispensable for normal retinal function, but is of major importance for photoreceptor degeneration under pathological conditions. Moreover, our results suggest that PARP dependent cell death or PARthanatos may play a major role in retinal degeneration and highlight the possibility to use specific PARP inhibitors for the treatment of RP.
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Affiliation(s)
- Ayse Sahaboglu
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Naoyuki Tanimoto
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Jasvir Kaur
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Javier Sancho-Pelluz
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Gesine Huber
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Edda Fahl
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Blanca Arango-Gonzalez
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Eberhart Zrenner
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Per Ekström
- Department of Ophthalmology, Clinical Sciences Lund, University of Lund, Lund, Sweden
| | - Hubert Löwenheim
- Otolaryngology Department, University of Tübingen, Tübingen, Germany
| | - Mathias Seeliger
- Ocular Neurodegeneration Research Group, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - François Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
- * E-mail:
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90
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Trifunović D, Dengler K, Michalakis S, Zrenner E, Wissinger B, Paquet-Durand F. cGMP-dependent cone photoreceptor degeneration in the cpfl1 mouse retina. J Comp Neurol 2010; 518:3604-17. [PMID: 20593360 DOI: 10.1002/cne.22416] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Inherited retinal degeneration affecting both rod and cone photoreceptors constitutes one of the leading causes of blindness in the developed world. Such degeneration is at present untreatable, and the underlying neurodegenerative mechanisms are unknown, even though certain genetic causes have been established. The rd1 mouse is one of the best characterized animal models for rod photoreceptor degeneration, whereas the cpfl1 mouse is a recently discovered model for cone cell death. Because both animal models are affected by functionally similar mutations in the rod and cone phosphodiesterase 6 genes, respectively, we asked whether the mechanisms of photoreceptor degeneration in these two mouse lines share common pathways. In the present study, we followed the temporal progression of photoreceptor degeneration in the cpfl1 retina, correlated it with specific metabolic markers, and compared it with the wild-type and the rd1 situation. Similar to corresponding rd1 observations, cpfl1 cone photoreceptor cell death was associated with an accumulation of cyclic guanosine monophosphate (cGMP), activity of calpains, and phosphorylation of vasodilator-stimulated protein (VASP). Cone degeneration progressed rapidly, with a peak in cell death around postnatal day 24. Furthermore, cpfl1 cone photoreceptor migration during early postnatal development was delayed significantly compared with the corresponding wild-type retina. The finding that rod and cone photoreceptor degeneration was associated with the same metabolic markers suggests that in both cell types similar degenerative mechanisms are active. This raises the possibility that equivalent neuroprotective strategies may be used to prevent both rod and cone photoreceptor degeneration.
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Affiliation(s)
- Dragana Trifunović
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, 72076 Germany
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91
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Paquet-Durand F, Sanges D, McCall J, Silva J, van Veen T, Marigo V, Ekström P. Photoreceptor rescue and toxicity induced by different calpain inhibitors. J Neurochem 2010; 115:930-40. [PMID: 20807308 DOI: 10.1111/j.1471-4159.2010.06983.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photoreceptor degeneration is the hallmark of a group of inherited blinding diseases collectively termed retinitis pigmentosa (RP); a major cause of blindness in humans. RP is at present untreatable and the underlying neurodegenerative mechanisms are largely unknown, even though the genetic causes are often established. The activation of calpain-type proteases may play an important role in cell death in various neuronal tissues, including the retina. We therefore tested the efficacy of two different calpain inhibitors in preventing cell death in the retinal degeneration (rd1) human homologous mouse model for RP. Pharmacological inhibition of calpain activity in rd1 organotypic retinal explants had ambiguous effects on photoreceptor viability. Calpain inhibitor XI had protective effects when applied for short periods of time (16 h) but demonstrated substantial levels of toxicity in both wild-type and rd1 retina when used over several days. In contrast, the highly specific calpain inhibitor calpastatin peptide reduced photoreceptor cell death in vitro after both short and prolonged exposure, an effect that was also evident after in vivo application via intravitreal injection. These findings highlight the importance of calpain activation for photoreceptor cell death but also for photoreceptor survival and propose the use of highly specific calpain inhibitors to prevent or delay RP.
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Affiliation(s)
- François Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
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92
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Restoration of cone vision in the CNGA3-/- mouse model of congenital complete lack of cone photoreceptor function. Mol Ther 2010; 18:2057-63. [PMID: 20628362 DOI: 10.1038/mt.2010.149] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Congenital absence of cone photoreceptor function is associated with strongly impaired daylight vision and loss of color discrimination in human achromatopsia. Here, we introduce viral gene replacement therapy as a potential treatment for this disease in the CNGA3(-/-) mouse model. We show that such therapy can restore cone-specific visual processing in the central nervous system even if cone photoreceptors had been nonfunctional from birth. The restoration of cone vision was assessed at different stages along the visual pathway. Treated CNGA3(-/-) mice were able to generate cone photoreceptor responses and to transfer these signals to bipolar cells. In support, we found morphologically that treated cones expressed regular cyclic nucleotide-gated (CNG) channel complexes and opsins in outer segments, which previously they did not. Moreover, expression of CNGA3 normalized cyclic guanosine monophosphate (cGMP) levels in cones, delayed cone cell death and reduced the inflammatory response of Müller glia cells that is typical of retinal degenerations. Furthermore, ganglion cells from treated, but not from untreated, CNGA3(-/-) mice displayed cone-driven, light-evoked, spiking activity, indicating that signals generated in the outer retina are transmitted to the brain. Finally, we demonstrate that this newly acquired sensory information was translated into cone-mediated, vision-guided behavior.
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93
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Johnson JLF, Leroux MR. cAMP and cGMP signaling: sensory systems with prokaryotic roots adopted by eukaryotic cilia. Trends Cell Biol 2010; 20:435-44. [PMID: 20541938 DOI: 10.1016/j.tcb.2010.05.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 10/19/2022]
Abstract
An exciting discovery of the new millennium is that primary cilia, organelles found on most eukaryotic cells, play crucial roles in vertebrate development by modulating Hedgehog, Wnt and PDGF signaling. Analysis of the literature and sequence databases reveals that the ancient signal transduction pathway, which uses cGMP in eukaryotes or related cyclic di-GMP in bacteria, exists in virtually all eukaryotes. However, many eukaryotes that secondarily lost cilia during evolution, including flowering plants, slime molds and most fungi, lack otherwise evolutionarily conserved cGMP signaling components. Based on this intriguing phylogenetic distribution, the presence of cGMP signaling proteins within cilia, and the indispensable roles that cGMP plays in transducing environmental signals in divergent ciliated cells (e.g. vertebrate photoreceptors and Caenorhabditis elegans sensory neurons), we propose that cGMP signaling has a strong ciliary basis. cAMP signaling, also inherent to bacteria and crucial for cilium-dependent olfaction, similarly appears to have widespread usage in diverse cilia. Thus, we argue here that both cyclic nucleotides play essential and potentially ubiquitous roles in modulating ciliary functions.
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Affiliation(s)
- Jacque-Lynne F Johnson
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
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94
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Johlfs MG, Fiscus RR. Protein kinase G type-Iα phosphorylates the apoptosis-regulating protein Bad at serine 155 and protects against apoptosis in N1E-115 cells. Neurochem Int 2010; 56:546-53. [DOI: 10.1016/j.neuint.2009.12.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 12/14/2009] [Accepted: 12/21/2009] [Indexed: 12/01/2022]
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95
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Acosta ML, Shin YS, Ready S, Fletcher EL, Christie DL, Kalloniatis M. Retinal metabolic state of the proline-23-histidine rat model of retinitis pigmentosa. Am J Physiol Cell Physiol 2009; 298:C764-74. [PMID: 20032515 DOI: 10.1152/ajpcell.00253.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the metabolic changes that precede cell death in the dystrophic proline-23-histidine (P23H) line 3 (P23H-3) rat retina compared with the normal Sprague-Dawley (SD) rat retina. Metabolite levels and metabolic enzymes were analyzed early in development and during the early stages of degeneration in the P23H-3 retina. Control and degenerating retinas showed an age-dependent change in metabolite levels and enzymatic activity, particularly around the time when phototransduction was activated. However, lactate dehydrogenase (LDH) activity was significantly higher in P23H-3 than SD retina before the onset of photoreceptor death. The creatine/phosphocreatine system did not contribute to the increase in ATP, because phosphocreatine levels, creatine kinase, and expression of the creatine transporter remained constant. However, Na(+)-K(+)-ATPase and Mg(2+)-Ca(2+)-ATPase activities were increased in the developing P23H-3 retina. Therefore, photoreceptor apoptosis in the P23H-3 retina occurs in an environment of increased LDH, ATPase activity, and higher-than-normal ATP levels. We tested the effect of metabolic challenge to the retina by inhibiting monocarboxylate transport with alpha-cyano-4-hydroxycinnamic acid or systemically administering the phosphodiesterase inhibitor sildenafil. Secondary to monocarboxylate transport inhibition, the P23H-3 retina did not demonstrate alterations in metabolic activity. However, administration of sildenafil significantly reduced LDH activity in the P23H-3 retina and increased the number of terminal deoxynucleotidyl transferase biotin-dUPT nick end-labeled photoreceptor cells. Photoreceptor cells with a rhodopsin mutation display an increase in apoptotic markers secondary to inhibition of a phototransduction enzyme (phosphodiesterase), suggesting increased susceptibility to altered cation entry.
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Affiliation(s)
- Monica L Acosta
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
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