| 1. |
- Paquet-Durand, F., et al.
(författare)
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How Long Does a Photoreceptor Cell Take to Die? Implications for the Causative Cell Death Mechanisms
- 2014
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Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer New York. - 0065-2598. ; 801, s. 575-581
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Tidskriftsartikel (refereegranskat)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 rdl 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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| 2. |
- Sahaboglu, A., et al.
(författare)
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Retinitis pigmentosa: rapid neurodegeneration is governed by slow cell death mechanisms
- 2013
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Ingår i: Cell Death & Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 4
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Tidskriftsartikel (refereegranskat)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 guanosinemono-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. Cell Death and Disease (2013) 4, e488; doi: 10.1038/cddis.2013.12; published online 7 February 2013
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| 3. |
- Sancho-Pelluz, J., et al.
(författare)
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Excessive HDAC activation is critical for neurodegeneration in the rd1 mouse
- 2010
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Ingår i: Cell Death & Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 1
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Tidskriftsartikel (refereegranskat)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. Cell Death and Disease (2010) 1, e24; doi:10.1038/cddis.2010.4; published online 11 February 2010
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| 4. |
- Ekström, Per, et al.
(författare)
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Novel In Situ Activity Assays for the Quantitative Molecular Analysis of Neurodegenerative Processes in the Retina
- 2014
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Ingår i: Current Medicinal Chemistry. - : Bentham Science Publishers Ltd.. - 0929-8673. ; 21:30, s. 3478-3493
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of neuronal cell death are still only poorly understood, which has hindered the advancement of therapies for many currently untreatable neurodegenerative diseases. This calls for the development of new methods which reveal critical molecular mechanisms of the celldeath machinery with both high sensitivity and cellular resolution. Using animal models for hereditary neurodegeneration in the retina, we have developed or adapted different biochemical assays to determine the enzymatic activities of calpain, poly-ADP-ribose-polymerase (PARP), and histone deacetylase (HDAC) directly and in situ. Additionally, the enzymatic activity of cGMP-dependent protein kinase (PKG) was assessed indirectly using in situ immunohistological techniques to detect PKG-activity-dependent products. Combining these assays with in situ cell death markers revealed close temporospatial correlations, suggesting causal connections between the PKG, HDAC, PARP and calpain activities and neuronal cell death. Using different pharmacological and genetic manipulations, causality could indeed be demonstrated. Surprisingly, the often dramatic rises in metabolic activities didnot match by corresponding increases in expression, highlighting the importance of analyses of protein activities at the cellular level. The above mentioned studies identified a number of metabolic processes previously unknownto be involved in inherited retinal degeneration. Comparing different animal retinal degeneration models uncovered striking similarities in enzymatic activities, suggesting a generality of the destructive pathways. Taken together, these findings provided a number of novel targets for neuroprotection and as such opened up new perspectives for the therapy of hereditary neurodegeneration in the retina and possibly other parts of the central nervous system.
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