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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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. Adv Exp Med Biol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Trifunović D, Sahaboglu A, Kaur J, Mencl S, Zrenner E, Ueffing M, Arango-Gonzalez B, Paquet-Durand F. Neuroprotective strategies for the treatment of inherited photoreceptor degeneration. Curr Mol Med 2012; 12:598-612. [PMID: 22515977 DOI: 10.2174/156652412800620048] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/19/2011] [Accepted: 12/23/2011] [Indexed: 11/22/2022]
Abstract
Photoreceptor degeneration is the hallmark of several groups of inherited neurodegenerative diseases causing blindness in humans. These diseases are a major cause of visual handicap and to date no satisfactory treatment is available. Here, we briefly review different approaches for the treatment of photoreceptor degeneration, to then focus on neuroprotection. Up to date, translation of experimental neuroprotection into a clinical setting has faced major obstacles, which are in part due to an incomplete understanding of the regulation of pro-survival as well as neurodegenerative mechanisms. Previous approaches were often based on the hypothesis that photoreceptor cell death was governed by a single, apoptotic cell death mechanism. This perception has turned out too simple as recent work has demonstrated that photoreceptor cell death is governed by non-apoptotic mechanisms as well. Moreover, there is evidence, that several different destructive processes are executed in parallel. Briefly reviewing the complexity of degenerative mechanisms, this review discusses relevant pathways, options to target signaling cascades, final common denominators of cell death, and the interplay of events executing cell death. In particular, we focus on cGMP-signaling, epigenetic and proteolytic processes and the corresponding enzymatic activities that were recently shown to be causally related to retinal degeneration. Finally, we illustrate how a better understanding of destructive mechanisms may enable identification and validation of novel targets for neuroprotection, and allow development of next generation neuroprotective treatments as well as combination therapy.
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Affiliation(s)
- D Trifunović
- Tubingen University, Institute for Ophthalmic Research, Division of Experimental Ophthalmology, Cell Death Mechanisms Group, Rontgenweg 11, 72076 Tubingen, Germany
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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: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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