1
|
Chen Y, Zizmare L, Calbiague V, Wang L, Yu S, Herberg FW, Schmachtenberg O, Paquet-Durand F, Trautwein C. Retinal metabolism displays evidence for uncoupling of glycolysis and oxidative phosphorylation via Cori-, Cahill-, and mini-Krebs-cycle. eLife 2024; 12:RP91141. [PMID: 38739438 PMCID: PMC11090511 DOI: 10.7554/elife.91141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024] Open
Abstract
The retina consumes massive amounts of energy, yet its metabolism and substrate exploitation remain poorly understood. Here, we used a murine explant model to manipulate retinal energy metabolism under entirely controlled conditions and utilised 1H-NMR spectroscopy-based metabolomics, in situ enzyme detection, and cell viability readouts to uncover the pathways of retinal energy production. Our experimental manipulations resulted in varying degrees of photoreceptor degeneration, while the inner retina and retinal pigment epithelium were essentially unaffected. This selective vulnerability of photoreceptors suggested very specific adaptations in their energy metabolism. Rod photoreceptors were found to rely strongly on oxidative phosphorylation, but only mildly on glycolysis. Conversely, cone photoreceptors were dependent on glycolysis but insensitive to electron transport chain decoupling. Importantly, photoreceptors appeared to uncouple glycolytic and Krebs-cycle metabolism via three different pathways: (1) the mini-Krebs-cycle, fuelled by glutamine and branched chain amino acids, generating N-acetylaspartate; (2) the alanine-generating Cahill-cycle; (3) the lactate-releasing Cori-cycle. Moreover, the metabolomics data indicated a shuttling of taurine and hypotaurine between the retinal pigment epithelium and photoreceptors, likely resulting in an additional net transfer of reducing power to photoreceptors. These findings expand our understanding of retinal physiology and pathology and shed new light on neuronal energy homeostasis and the pathogenesis of neurodegenerative diseases.
Collapse
Affiliation(s)
- Yiyi Chen
- Institute for Ophthalmic Research, University of TübingenTuebingenGermany
| | - Laimdota Zizmare
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of TübingenTuebingenGermany
- Core Facility Metabolomics, Faculty of Medicine, University of TübingenTuebingenGermany
| | - Victor Calbiague
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaísoChile
| | - Lan Wang
- Institute for Ophthalmic Research, University of TübingenTuebingenGermany
| | - Shirley Yu
- Institute for Ophthalmic Research, University of TübingenTuebingenGermany
| | - Fritz W Herberg
- Biochemistry Department, University of KasselTuebingenGermany
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de ValparaísoValparaísoChile
| | | | - Christoph Trautwein
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of TübingenTuebingenGermany
- Core Facility Metabolomics, Faculty of Medicine, University of TübingenTuebingenGermany
| |
Collapse
|
2
|
Jimeno D, Lillo C, de la Villa P, Calzada N, Santos E, Fernández-Medarde A. GRF2 Is Crucial for Cone Photoreceptor Viability and Ribbon Synapse Formation in the Mouse Retina. Cells 2023; 12:2574. [PMID: 37947653 PMCID: PMC10650203 DOI: 10.3390/cells12212574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 10/27/2023] [Accepted: 11/03/2023] [Indexed: 11/12/2023] Open
Abstract
Using constitutive GRF1/2 knockout mice, we showed previously that GRF2 is a key regulator of nuclear migration in retinal cone photoreceptors. To evaluate the functional relevance of that cellular process for two putative targets of the GEF activity of GRF2 (RAC1 and CDC42), here we compared the structural and functional retinal phenotypes resulting from conditional targeting of RAC1 or CDC42 in the cone photoreceptors of constitutive GRF2KO and GRF2WT mice. We observed that single RAC1 disruption did not cause any obvious morphological or physiological changes in the retinas of GRF2WT mice, and did not modify either the phenotypic alterations previously described in the retinal photoreceptor layer of GRF2KO mice. In contrast, the single ablation of CDC42 in the cone photoreceptors of GRF2WT mice resulted in clear alterations of nuclear movement that, unlike those of the GRF2KO retinas, were not accompanied by electrophysiological defects or slow, progressive cone cell degeneration. On the other hand, the concomitant disruption of GRF2 and CDC42 in the cone photoreceptors resulted, somewhat surprisingly, in a normalized pattern of nuclear positioning/movement, similar to that physiologically observed in GRF2WT mice, along with worsened patterns of electrophysiological responses and faster rates of cell death/disappearance than those previously recorded in single GRF2KO cone cells. Interestingly, the increased rates of cone cell apoptosis/death observed in single GRF2KO and double-knockout GRF2KO/CDC42KO retinas correlated with the electron microscopic detection of significant ultrastructural alterations (flattening) of their retinal ribbon synapses that were not otherwise observed at all in single-knockout CDC42KO retinas. Our observations identify GRF2 and CDC42 (but not RAC1) as key regulators of retinal processes controlling cone photoreceptor nuclear positioning and survival, and support the notion of GRF2 loss-of-function mutations as potential drivers of cone retinal dystrophies.
Collapse
Affiliation(s)
- David Jimeno
- Centro de Investigación del Cáncer-Instituto de Biologıá Molecular y Celular del Cáncer (CSIC–Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | | | - Pedro de la Villa
- Departamento de Biología de Sistemas, Universidad de Alcalá, 28871 Alcalá de Henares, and IRYCIS, 28034 Madrid, Spain
| | - Nuria Calzada
- Centro de Investigación del Cáncer-Instituto de Biologıá Molecular y Celular del Cáncer (CSIC–Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Eugenio Santos
- Centro de Investigación del Cáncer-Instituto de Biologıá Molecular y Celular del Cáncer (CSIC–Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| | - Alberto Fernández-Medarde
- Centro de Investigación del Cáncer-Instituto de Biologıá Molecular y Celular del Cáncer (CSIC–Universidad de Salamanca) and CIBERONC, 37007 Salamanca, Spain
| |
Collapse
|
3
|
Li S, Ma H, Yang F, Ding X. cGMP Signaling in Photoreceptor Degeneration. Int J Mol Sci 2023; 24:11200. [PMID: 37446378 PMCID: PMC10342299 DOI: 10.3390/ijms241311200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Photoreceptors in the retina are highly specialized neurons with photosensitive molecules in the outer segment that transform light into chemical and electrical signals, and these signals are ultimately relayed to the visual cortex in the brain to form vision. Photoreceptors are composed of rods and cones. Rods are responsible for dim light vision, whereas cones are responsible for bright light, color vision, and visual acuity. Photoreceptors undergo progressive degeneration over time in many hereditary and age-related retinal diseases. Despite the remarkable heterogeneity of disease-causing genes, environmental factors, and pathogenesis, the progressive death of rod and cone photoreceptors ultimately leads to loss of vision/blindness. There are currently no treatments available for retinal degeneration. Cyclic guanosine 3', 5'-monophosphate (cGMP) plays a pivotal role in phototransduction. cGMP governs the cyclic nucleotide-gated (CNG) channels on the plasma membrane of the photoreceptor outer segments, thereby regulating membrane potential and signal transmission. By gating the CNG channels, cGMP regulates cellular Ca2+ homeostasis and signal transduction. As a second messenger, cGMP activates the cGMP-dependent protein kinase G (PKG), which regulates numerous targets/cellular events. The dysregulation of cGMP signaling is observed in varieties of photoreceptor/retinal degenerative diseases. Abnormally elevated cGMP signaling interferes with various cellular events, which ultimately leads to photoreceptor degeneration. In line with this, strategies to reduce cellular cGMP signaling result in photoreceptor protection in mouse models of retinal degeneration. The potential mechanisms underlying cGMP signaling-induced photoreceptor degeneration involve the activation of PKG and impaired Ca2+ homeostasis/Ca2+ overload, resulting from overactivation of the CNG channels, as well as the subsequent activation of the downstream cellular stress/death pathways. Thus, targeting the cellular cGMP/PKG signaling and the Ca2+-regulating pathways represents a significant strategy for photoreceptor protection in retinal degenerative diseases.
Collapse
Affiliation(s)
| | | | | | - Xiqin Ding
- Department of Cell Biology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (S.L.); (H.M.); (F.Y.)
| |
Collapse
|
4
|
Lu CF, Zhou YN, Zhang J, Su S, Liu Y, Peng GH, Zang W, Cao J. The role of epigenetic methylation/demethylation in the regulation of retinal photoreceptors. Front Cell Dev Biol 2023; 11:1149132. [PMID: 37305686 PMCID: PMC10251769 DOI: 10.3389/fcell.2023.1149132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 05/09/2023] [Indexed: 06/13/2023] Open
Abstract
Photoreceptors are integral and crucial for the retina, as they convert light into electrical signals. Epigenetics plays a vital role in determining the precise expression of genetic information in space and time during the development and maturation of photoreceptors, cell differentiation, degeneration, death, and various pathological processes. Epigenetic regulation has three main manifestations: histone modification, DNA methylation, and RNA-based mechanisms, where methylation is involved in two regulatory mechanisms-histone methylation and DNA methylation. DNA methylation is the most studied form of epigenetic modification, while histone methylation is a relatively stable regulatory mechanism. Evidence suggests that normal methylation regulation is essential for the growth and development of photoreceptors and the maintenance of their functions, while abnormal methylation can lead to many pathological forms of photoreceptors. However, the role of methylation/demethylation in regulating retinal photoreceptors remains unclear. Therefore, this study aims to review the role of methylation/demethylation in regulating photoreceptors in various physiological and pathological situations and discuss the underlying mechanisms involved. Given the critical role of epigenetic regulation in gene expression and cellular differentiation, investigating the specific molecular mechanisms underlying these processes in photoreceptors may provide valuable insights into the pathogenesis of retinal diseases. Moreover, understanding these mechanisms could lead to the development of novel therapies that target the epigenetic machinery, thereby promoting the maintenance of retinal function throughout an individual's lifespan.
Collapse
Affiliation(s)
- Chao-Fan Lu
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Ya-Nan Zhou
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jingjing Zhang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Songxue Su
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Yupeng Liu
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Guang-Hua Peng
- Department of Pathophysiology, Basic Medical College, Zhengzhou University, Zhengzhou, China
- Laboratory of Visual Cell Differentiation and Regulation, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Weidong Zang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jing Cao
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| |
Collapse
|
5
|
Brunet AA, Hunt DM, Mellough C, Harvey AR, Carvalho LS. Compensatory Cone-Mediated Mechanisms in Inherited Retinal Degeneration Mouse Models: A Functional and Gene Expression Analysis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:347-352. [PMID: 37440055 DOI: 10.1007/978-3-031-27681-1_50] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
The retina undergoes compensatory changes in response to progressive photoreceptor loss/dysfunction; however, studies of inherited retinal diseases (IRDs) often lack a temporal connection between gene expression and visual function. Here, we used three mouse models of IRD - Cnga3-/-, Pde6ccpfl1, and Rd1 - to investigate over time the effect of photoreceptor degeneration, particularly cones, on visual function and gene expression. Changes to gene expression include increases in cell survival and cell death genes in Pde6ccpfl1 before significant cell loss, as well as an increase in cone-specific genes in the Rd1 at the peak of rod death. We show that Cnga3-/- and Pde6ccpfl1 mice maintained photopic visual acuity via optomotor responses, despite no recordable cone electroretinogram (ERG), while functional measures and photoreceptors loss were correlated in Rd1 mice. There were also significant changes to oscillatory potentials (OPs) in Cnga3-/- and Pde6ccpfl1, implying an effect on inner retinal cells as a result of cone degeneration. These results indicate a potentially malleable retinal environment following cone degeneration; however, further investigation is needed to elucidate how these changes compensate for the loss of cone function.
Collapse
Affiliation(s)
- Alicia A Brunet
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Crawley, WA, Australia.
- Lions Eye Institute Ltd., Nedlands, WA, Australia.
| | - David M Hunt
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Crawley, WA, Australia
- Lions Eye Institute Ltd., Nedlands, WA, Australia
| | - Carla Mellough
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Crawley, WA, Australia
- Lions Eye Institute Ltd., Nedlands, WA, Australia
| | - Alan R Harvey
- School of Human Sciences, The University of Western Australia, Crawley, WA, Australia
- Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia
| | - Livia S Carvalho
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Crawley, WA, Australia
- Lions Eye Institute Ltd., Nedlands, WA, Australia
| |
Collapse
|
6
|
Miller AL, Fuller-Carter PI, Masarini K, Samardzija M, Carter KW, Rashwan R, Lim XR, Brunet AA, Chopra A, Ram R, Grimm C, Ueffing M, Carvalho LS, Trifunović D. Increased H3K27 trimethylation contributes to cone survival in a mouse model of cone dystrophy. Cell Mol Life Sci 2022; 79:409. [PMID: 35810394 PMCID: PMC9271452 DOI: 10.1007/s00018-022-04436-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 06/16/2022] [Accepted: 06/17/2022] [Indexed: 11/30/2022]
Abstract
Inherited retinal diseases (IRDs) are a heterogeneous group of blinding disorders, which result in dysfunction or death of the light-sensing cone and rod photoreceptors. Despite individual IRDs (Inherited retinal disease) being rare, collectively, they affect up to 1:2000 people worldwide, causing a significant socioeconomic burden, especially when cone-mediated central vision is affected. This study uses the Pde6ccpfl1 mouse model of achromatopsia, a cone-specific vision loss IRD (Inherited retinal disease), to investigate the potential gene-independent therapeutic benefits of a histone demethylase inhibitor GSK-J4 on cone cell survival. We investigated the effects of GSK-J4 treatment on cone cell survival in vivo and ex vivo and changes in cone-specific gene expression via single-cell RNA sequencing. A single intravitreal GSK-J4 injection led to transcriptional changes in pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, among other key epigenetic pathways, highlighting the complex interplay between methylation and acetylation in healthy and diseased cones. Furthermore, continuous administration of GSK-J4 in retinal explants increased cone survival. Our results suggest that IRD (Inherited retinal disease)-affected cones respond positively to epigenetic modulation of histones, indicating the potential of this approach in developing a broad class of novel therapies to slow cone degeneration.
Collapse
Affiliation(s)
- Annie L Miller
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia
- Centre for Ophthalmology and Visual Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
| | - Paula I Fuller-Carter
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia
| | - Klaudija Masarini
- Institute for Ophthalmic Research, Tübingen University, Elfriede-Aulhorn-Straße 7, 72076, Tübingen, Germany
| | - Marijana Samardzija
- Lab for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zürich, University of Zürich, Zurich, Switzerland
| | - Kim W Carter
- Analytical Computing Solutions, Willetton, WA, 6155, Australia
| | - Rabab Rashwan
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia
- Department of Microbiology and Immunology, Faculty of Medicine, Minia University, Minia, Egypt
| | - Xin Ru Lim
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia
- Centre for Ophthalmology and Visual Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
| | - Alicia A Brunet
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia
- Centre for Ophthalmology and Visual Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
| | - Abha Chopra
- Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, WA, Australia
- Department of Medicine, Vanderbilt University Medical Centre, Nashville, TN, USA
| | - Ramesh Ram
- Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, WA, Australia
| | - Christian Grimm
- Lab for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zürich, University of Zürich, Zurich, Switzerland
| | - Marius Ueffing
- Institute for Ophthalmic Research, Tübingen University, Elfriede-Aulhorn-Straße 7, 72076, Tübingen, Germany
| | - Livia S Carvalho
- Retinal Genomics and Therapy Group, Lions Eye Institute Ltd, 2 Verdun Street, Nedlands, WA, 6009, Australia.
- Centre for Ophthalmology and Visual Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
| | - Dragana Trifunović
- Institute for Ophthalmic Research, Tübingen University, Elfriede-Aulhorn-Straße 7, 72076, Tübingen, Germany.
| |
Collapse
|
7
|
Calpains as mechanistic drivers and therapeutic targets for ocular disease. Trends Mol Med 2022; 28:644-661. [PMID: 35641420 PMCID: PMC9345745 DOI: 10.1016/j.molmed.2022.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 11/18/2022]
Abstract
Ophthalmic neurodegenerative diseases encompass a wide array of molecular pathologies unified by calpain dysregulation. Calpains are calcium-dependent proteases that perpetuate cellular death and inflammation when hyperactivated. Calpain inhibition trials in other organs have faced pharmacological challenges, but the eye offers many advantages for the development and testing of targeted molecular therapeutics, including small molecules, peptides, engineered proteins, drug implants, and gene-based therapies. This review highlights structural mechanisms underlying calpain activation, distinct cellular expression patterns, and in vivo models that link calpain hyperactivity to human retinal and developmental disease. Optimizing therapeutic approaches for calpain-mediated eye diseases can help accelerate clinically feasible strategies for treating calpain dysregulation in other diseased tissues.
Collapse
|
8
|
Roy A, Tolone A, Hilhorst R, Groten J, Tomar T, Paquet-Durand F. Kinase activity profiling identifies putative downstream targets of cGMP/PKG signaling in inherited retinal neurodegeneration. Cell Death Dis 2022; 8:93. [PMID: 35241647 PMCID: PMC8894370 DOI: 10.1038/s41420-022-00897-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/16/2021] [Accepted: 02/08/2022] [Indexed: 11/15/2022]
Abstract
Inherited retinal diseases (IRDs) are a group of neurodegenerative disorders that lead to photoreceptor cell death and eventually blindness. IRDs are characterised by a high genetic heterogeneity, making it imperative to design mutation-independent therapies. Mutations in a number of IRD disease genes have been associated with a rise of cyclic 3’,5’-guanosine monophosphate (cGMP) levels in photoreceptors. Accordingly, the cGMP-dependent protein kinase (PKG) has emerged as a new potential target for the mutation-independent treatment of IRDs. However, the substrates of PKG and the downstream degenerative pathways triggered by its activity have yet to be determined. Here, we performed kinome activity profiling of different murine organotypic retinal explant cultures (diseased rd1 and wild-type controls) using multiplex peptide microarrays to identify proteins whose phosphorylation was significantly altered by PKG activity. In addition, we tested the downstream effect of a known PKG inhibitor CN03 in these organotypic retina cultures. Among the PKG substrates were potassium channels belonging to the Kv1 family (KCNA3, KCNA6), cyclic AMP-responsive element-binding protein 1 (CREB1), DNA topoisomerase 2-α (TOP2A), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (F263), and the glutamate ionotropic receptor kainate 2 (GRIK2). The retinal expression of these PKG targets was further confirmed by immunofluorescence and could be assigned to various neuronal cell types, including photoreceptors, horizontal cells, and ganglion cells. Taken together, this study confirmed the key role of PKG in photoreceptor cell death and identified new downstream targets of cGMP/PKG signalling that will improve the understanding of the degenerative mechanisms underlying IRDs.
Collapse
Affiliation(s)
- Akanksha Roy
- Division of Toxicology, Wageningen University and Research, 96708 WE, Wageningen, The Netherlands.,PamGene International B.V, 5200 BJ, s-Hertogenbosch, The Netherlands
| | - Arianna Tolone
- Cell Death Mechanism Group, Institute for Ophthalmic Research, Eberhard-Karls-Universität, Tübingen, 72072, Germany
| | - Riet Hilhorst
- PamGene International B.V, 5200 BJ, s-Hertogenbosch, The Netherlands
| | - John Groten
- Division of Toxicology, Wageningen University and Research, 96708 WE, Wageningen, The Netherlands.,PamGene International B.V, 5200 BJ, s-Hertogenbosch, The Netherlands
| | - Tushar Tomar
- PamGene International B.V, 5200 BJ, s-Hertogenbosch, The Netherlands.
| | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, Eberhard-Karls-Universität, Tübingen, 72072, Germany.
| |
Collapse
|
9
|
Brunet AA, Harvey AR, Carvalho LS. Primary and Secondary Cone Cell Death Mechanisms in Inherited Retinal Diseases and Potential Treatment Options. Int J Mol Sci 2022; 23:ijms23020726. [PMID: 35054919 PMCID: PMC8775779 DOI: 10.3390/ijms23020726] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/05/2022] [Accepted: 01/05/2022] [Indexed: 12/13/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a leading cause of blindness. To date, 260 disease-causing genes have been identified, but there is currently a lack of available and effective treatment options. Cone photoreceptors are responsible for daylight vision but are highly susceptible to disease progression, the loss of cone-mediated vision having the highest impact on the quality of life of IRD patients. Cone degeneration can occur either directly via mutations in cone-specific genes (primary cone death), or indirectly via the primary degeneration of rods followed by subsequent degeneration of cones (secondary cone death). How cones degenerate as a result of pathological mutations remains unclear, hindering the development of effective therapies for IRDs. This review aims to highlight similarities and differences between primary and secondary cone cell death in inherited retinal diseases in order to better define cone death mechanisms and further identify potential treatment options.
Collapse
Affiliation(s)
- Alicia A. Brunet
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
- Correspondence: ; Tel.: +61-423-359-714
| | - Alan R. Harvey
- School of Human Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Perron Institute for Neurological and Translational Science, 8 Verdun St, Nedlands, WA 6009, Australia
| | - Livia S. Carvalho
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
| |
Collapse
|
10
|
Yan J, Chen Y, Zhu Y, Paquet-Durand F. Programmed Non-Apoptotic Cell Death in Hereditary Retinal Degeneration: Crosstalk between cGMP-Dependent Pathways and PARthanatos? Int J Mol Sci 2021; 22:10567. [PMID: 34638907 PMCID: PMC8508647 DOI: 10.3390/ijms221910567] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/26/2021] [Accepted: 09/27/2021] [Indexed: 12/20/2022] Open
Abstract
Programmed cell death (PCD) is a highly regulated process that results in the orderly destruction of a cell. Many different forms of PCD may be distinguished, including apoptosis, PARthanatos, and cGMP-dependent cell death. Misregulation of PCD mechanisms may be the underlying cause of neurodegenerative diseases of the retina, including hereditary retinal degeneration (RD). RD relates to a group of diseases that affect photoreceptors and that are triggered by gene mutations that are often well known nowadays. Nevertheless, the cellular mechanisms of PCD triggered by disease-causing mutations are still poorly understood, and RD is mostly still untreatable. While investigations into the neurodegenerative mechanisms of RD have focused on apoptosis in the past two decades, recent evidence suggests a predominance of non-apoptotic processes as causative mechanisms. Research into these mechanisms carries the hope that the knowledge created can eventually be used to design targeted treatments to prevent photoreceptor loss. Hence, in this review, we summarize studies on PCD in RD, including on apoptosis, PARthanatos, and cGMP-dependent cell death. Then, we focus on a possible interplay between these mechanisms, covering cGMP-signaling targets, overactivation of poly(ADP-ribose)polymerase (PARP), energy depletion, Ca2+-permeable channels, and Ca2+-dependent proteases. Finally, an outlook is given into how specific features of cGMP-signaling and PARthanatos may be targeted by therapeutic interventions.
Collapse
Affiliation(s)
| | | | | | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Elfriede-Aulhorn-Strasse 7, 72076 Tübingen, Germany; (J.Y.); (Y.C.); (Y.Z.)
| |
Collapse
|
11
|
Burger CA, Albrecht NE, Jiang D, Liang JH, Poché RA, Samuel MA. LKB1 and AMPK instruct cone nuclear position to modify visual function. Cell Rep 2021; 34:108698. [PMID: 33535040 PMCID: PMC7906279 DOI: 10.1016/j.celrep.2021.108698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 11/06/2020] [Accepted: 01/06/2021] [Indexed: 12/17/2022] Open
Abstract
Cone photoreceptors detect light and are responsible for color vision. These cells display a distinct polarized morphology where nuclei are precisely aligned in the apical retina. However, little is known about the mechanisms involved in cone nuclear positioning or the impact of this organization on retina function. We show that the serine/threonine kinase LKB1 and one of its substrates, AMPK, regulate cone nuclear positioning. In the absence of either molecule, cone nuclei are misplaced along the axon, resulting in altered nuclear lamination. LKB1 is required specifically in cones to mediate this process, and disruptions in nuclear alignment result in reduced cone function. Together, these results identify molecular determinants of cone nuclear position and indicate that cone nuclear position alignment enables proper visual function.
Collapse
Affiliation(s)
- Courtney A Burger
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nicholas E Albrecht
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Danye Jiang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Justine H Liang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ross A Poché
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Melanie A Samuel
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA.
| |
Collapse
|
12
|
Yang P, Lockard R, Titus H, Hiblar J, Weller K, Wafai D, Weleber RG, Duvoisin RM, Morgans CW, Pennesi ME. Suppression of cGMP-Dependent Photoreceptor Cytotoxicity With Mycophenolate Is Neuroprotective in Murine Models of Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2021; 61:25. [PMID: 32785677 PMCID: PMC7441375 DOI: 10.1167/iovs.61.10.25] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose To determine the effect of mycophenolate mofetil (MMF) on retinal degeneration on two mouse models of retinitis pigmentosa. Methods Intraperitoneal injections of MMF were administered daily in rd10 and c57 mice starting at postoperative day 12 (P12) and rd1 mice starting at P8. The effect of MMF was assessed with optical coherence tomography, immunohistochemistry, electroretinography, and OptoMotry. Whole retinal cyclic guanosine monophosphate (cGMP) and mycophenolic acid levels were quantified with mass spectrometry. Photoreceptor cGMP cytotoxicity was evaluated with cell counts of cGMP immunostaining. Results MMF treatment significantly delays the onset of retinal degeneration and cGMP-dependent photoreceptor cytotoxicity in rd10 and rd1 mice, albeit a more modest effect in the latter. In rd10 mice, treatment with MMF showed robust preservation of the photoreceptors up to P22 with associated suppression of cGMP immunostaining and microglial activation; The neuroprotective effect diminished after P22, but outer retinal thickness was still significantly thicker by P35 and OptoMotry response was significantly better up to P60. Whereas cGMP immunostaining of the photoreceptors were present in rd10 and rd1 mice, hyperphysiological whole retinal cGMP levels were observed only in rd1 mice. Conclusions Early treatment with MMF confers potent neuroprotection in two animal models of RP by suppressing the cGMP-dependent common pathway for photoreceptor cell death. The neuroprotective effect of MMF on cGMP-dependent cytotoxicity occurs independently of the presence of hyperphysiological whole retinal cGMP levels. Thus our data suggest that MMF may be an important new class of neuroprotective agent that could be useful in the treatment of patients with RP.
Collapse
Affiliation(s)
- Paul Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Rachel Lockard
- School of Medicine, Oregon Health & Science University, Portland, Oregon, United States
| | - Hope Titus
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Jordan Hiblar
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Kyle Weller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Dahlia Wafai
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Richard G Weleber
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Robert M Duvoisin
- Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, United States
| | - Catherine W Morgans
- Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, Oregon, United States
| | - Mark E Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| |
Collapse
|
13
|
Brunet AA, Fuller-Carter PI, Miller AL, Voigt V, Vasiliou S, Rashwan R, Hunt DM, Carvalho LS. Validating Fluorescent Chrnb4.EGFP Mouse Models for the Study of Cone Photoreceptor Degeneration. Transl Vis Sci Technol 2020; 9:28. [PMID: 32879784 PMCID: PMC7442867 DOI: 10.1167/tvst.9.9.28] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/29/2020] [Indexed: 02/07/2023] Open
Abstract
Purpose To validate the application of a known transgenic mouse line with green fluorescent cones (Chrnb4.EGFP) to study cone photoreceptor biology and function in health and disease. Methods Chrnb4.EGFP retinas containing GFP+ cones were compared with retinas without the GFP transgene via immunohistochemistry, quantitative real-time polymerase chain reaction, electroretinograms, and flow cytometry. The Chrnb4.EGFP line was backcrossed to the mouse models of cone degeneration, Pde6ccpfl1 and Gnat2cpfl3 , generating the new lines Gnat2.GFP and Pde6c.GFP, which were also studied as described. Results GFP expression spanned the length of the cone cell in the Chrnb4.EGFP line, as well as in the novel Gnat2.GFP and Pde6c.GFP lines. The effect of GFP expression showed no significant changes to outer nuclear layer cell death, cone-specific gene expression, and immune response activation. A temporal decrease in GFP expression over time was observed, but GFP fluorescence was still detected through flow cytometry as late as 6 months. Furthermore, a functional analysis of photopic and scotopic electroretinogram responses of the Chrnb4 mouse showed no significant difference between GFP- and GFP+ mice, whereas electroretinogram recordings for the Pde6c.GFP and Gnat2.GFP lines matched previous reports from the original lines. Conclusions This study demonstrates that the Chrnb4.EGFP mouse can be a powerful tool to overcome the limitations of studying cone biology, including the use of this line to study different types of cone degeneration. Translational Relevance This work validates research tools that could potentially offer more reliable preclinical data in the development of treatments for cone-mediated vision loss conditions, shortening the gap to clinical translation.
Collapse
Affiliation(s)
- Alicia A. Brunet
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- Lions Eye Institute, Nedlands, Western Australia, Australia
| | | | - Annie L. Miller
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- Lions Eye Institute, Nedlands, Western Australia, Australia
| | | | | | - Rabab Rashwan
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Department of Microbiology and Immunology, Faculty of Medicine, Minia University, Minia, Egypt
| | - David M. Hunt
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- Lions Eye Institute, Nedlands, Western Australia, Australia
| | - Livia S. Carvalho
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
- Lions Eye Institute, Nedlands, Western Australia, Australia
| |
Collapse
|
14
|
Power MJ, Rogerson LE, Schubert T, Berens P, Euler T, Paquet-Durand F. Systematic spatiotemporal mapping reveals divergent cell death pathways in three mouse models of hereditary retinal degeneration. J Comp Neurol 2019; 528:1113-1139. [PMID: 31710697 DOI: 10.1002/cne.24807] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/06/2019] [Accepted: 10/20/2019] [Indexed: 12/20/2022]
Abstract
Calcium (Ca2+ ) dysregulation has been linked to neuronal cell death, including in hereditary retinal degeneration. Ca2+ dysregulation is thought to cause rod and cone photoreceptor cell death. Spatial and temporal heterogeneities in retinal disease models have hampered validation of this hypothesis. We examined the role of Ca2+ in photoreceptor degeneration, assessing the activation pattern of Ca2+ -dependent calpain proteases, generating spatiotemporal maps of the entire retina in the cpfl1 mouse model for primary cone degeneration, and in the rd1 and rd10 models for primary rod degeneration. We used Gaussian process models to distinguish the temporal sequences of degenerative molecular processes from other variability sources.In the rd1 and rd10 models, spatiotemporal pattern of increased calpain activity matched the progression of primary rod degeneration. High calpain activity coincided with activation of the calpain-2 isoform but not with calpain-1, suggesting differential roles for both calpain isoforms. Primary rod loss was linked to upregulation of apoptosis-inducing factor, although only a minute fraction of cells showed activity of the apoptotic marker caspase-3. After primary rod degeneration concluded, caspase-3 activation appeared in cones, suggesting apoptosis as the dominant mechanism for secondary cone loss. Gaussian process models highlighted calpain activity as a key event during primary rod photoreceptor cell death. Our data suggest a causal link between Ca2+ dysregulation and primary, nonapoptotic degeneration of photoreceptors and a role for apoptosis in secondary degeneration of cones, highlighting the importance of the spatial and temporal location of key molecular events, which may guide the evaluation of new therapies.
Collapse
Affiliation(s)
- Michael J Power
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany.,Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Tübingen, Germany
| | - Luke E Rogerson
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany.,Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Tübingen, Germany.,Bernstein Center for Computational Neuroscience, Tübingen, Germany.,Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany
| | - Timm Schubert
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany
| | - Philipp Berens
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany.,Bernstein Center for Computational Neuroscience, Tübingen, Germany.,Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany
| | - Thomas Euler
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Centre for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany.,Bernstein Center for Computational Neuroscience, Tübingen, Germany
| | | |
Collapse
|
15
|
Power M, Das S, Schütze K, Marigo V, Ekström P, Paquet-Durand F. Cellular mechanisms of hereditary photoreceptor degeneration - Focus on cGMP. Prog Retin Eye Res 2019; 74:100772. [PMID: 31374251 DOI: 10.1016/j.preteyeres.2019.07.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 07/25/2019] [Accepted: 07/29/2019] [Indexed: 12/21/2022]
Abstract
The cellular mechanisms underlying hereditary photoreceptor degeneration are still poorly understood, a problem that is exacerbated by the enormous genetic heterogeneity of this disease group. However, the last decade has yielded a wealth of new knowledge on degenerative pathways and their diversity. Notably, a central role of cGMP-signalling has surfaced for photoreceptor cell death triggered by a subset of disease-causing mutations. In this review, we examine key aspects relevant for photoreceptor degeneration of hereditary origin. The topics covered include energy metabolism, epigenetics, protein quality control, as well as cGMP- and Ca2+-signalling, and how the related molecular and metabolic processes may trigger photoreceptor demise. We compare and integrate evidence on different cell death mechanisms that have been associated with photoreceptor degeneration, including apoptosis, necrosis, necroptosis, and PARthanatos. A special focus is then put on the mechanisms of cGMP-dependent cell death and how exceedingly high photoreceptor cGMP levels may cause activation of Ca2+-dependent calpain-type proteases, histone deacetylases and poly-ADP-ribose polymerase. An evaluation of the available literature reveals that a large group of patients suffering from hereditary photoreceptor degeneration carry mutations that are likely to trigger cGMP-dependent cell death, making this pathway a prime target for future therapy development. Finally, an outlook is given into technological and methodological developments that will with time likely contribute to a comprehensive overview over the entire metabolic complexity of photoreceptor cell death. Building on such developments, new imaging technology and novel biomarkers may be used to develop clinical test strategies, that fully consider the genetic heterogeneity of hereditary retinal degenerations, in order to facilitate clinical testing of novel treatment approaches.
Collapse
Affiliation(s)
- Michael Power
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Centre for Integrative Neurosciences (CIN), University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | - Soumyaparna Das
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany; Graduate Training Centre of Neuroscience (GTC), University of Tübingen, Germany
| | | | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Italy
| | - Per Ekström
- Ophthalmology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, Sweden
| | - François Paquet-Durand
- Cell Death Mechanism Group, Institute for Ophthalmic Research, University of Tübingen, Germany.
| |
Collapse
|
16
|
The Leber Congenital Amaurosis-Linked Protein AIPL1 and Its Critical Role in Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:381-386. [PMID: 29721967 DOI: 10.1007/978-3-319-75402-4_47] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Mutations in the photoreceptor/pineal-expressed gene, aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1), are mainly associated with autosomal recessive Leber congenital amaurosis (LCA), the most severe form of inherited retinopathy that occurs in early childhood. AIPL1 functions as a photoreceptor-specific molecular co-chaperone that interacts specifically with the molecular chaperones HSP90 and HSP70 to facilitate the correct folding and assembly of the retinal cGMP phosphodiesterase (PDE6) holoenzyme. The absence of AIPL1 leads to a dramatic degeneration of rod and cone cells and a complete loss of any light-dependent electrical response. Here we review the important role of AIPL1 in photoreceptor functionality.
Collapse
|
17
|
Mencl S, Trifunović D, Zrenner E, Paquet-Durand F. PKG-Dependent Cell Death in 661W Cone Photoreceptor-like Cell Cultures (Experimental Study). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:511-517. [PMID: 29721983 DOI: 10.1007/978-3-319-75402-4_63] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In humans cone photoreceptors are responsible for high-resolution colour vision. A variety of retinal diseases can compromise cone viability, and, at present, no satisfactory treatment options are available. Here, we present data towards establishing a reliable, high-throughput assay system that will facilitate the search for cone neuroprotective compounds using the murine-photoreceptor cell line 661 W. To further characterize 661 W cells, a retinal marker study was performed, followed by the induction of cell death using paradigms over-activating cGMP-dependent protein kinase G (PKG). We found that 661 W cells may be used to mimic specific aspects of cone degeneration and may thus be valuable for future compound screening studies.
Collapse
Affiliation(s)
- Stine Mencl
- University Hospital Essen, Department of Neurology, Essen, Germany
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Dragana Trifunović
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Eberhart Zrenner
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
- Centre for Integrative Neuroscience (CIN), Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - François Paquet-Durand
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany.
| |
Collapse
|
18
|
Do cGMP Levels Drive the Speed of Photoreceptor Degeneration? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:327-333. [PMID: 29721960 DOI: 10.1007/978-3-319-75402-4_40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Humans with mutations in the phototransduction pathway develop forms of retinal degeneration, such as retinitis pigmentosa, cone dystrophy, or Leber congenital amaurosis. Similarly, numerous phototransduction mutant animal models resemble retinal degeneration. In our lab, using a zebrafish model, we study cone-specific phototransduction mutants. cGMP is the second messenger in the phototransduction pathway, and abnormal cGMP levels are associated with photoreceptor death. Rd1, a rod-specific phosphodiesterase 6 (Pde6) subunit mutant in mice, is one of the most widely used animal models for retinal degeneration. Rd1 mutant mice accumulate cGMP, causing rapid photoreceptor degeneration. However, much less is known about photoreceptor mutants producing abnormally low levels of cGMP. Here, focusing on Pde6 mutants in zebrafish and mice, we propose a correlation between cGMP levels and speed of photoreceptor degeneration.
Collapse
|
19
|
HDAC Inhibition Prevents Primary Cone Degeneration Even After the Onset of Degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1185:383-387. [PMID: 31884642 DOI: 10.1007/978-3-030-27378-1_63] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cone photoreceptor loss is the main cause of color blindness and loss of visual acuity in patients suffering from inherited cone dystrophies. Despite the crucial role of cones in everyday life, knowledge on mechanisms of cone cell death and the identification of potential targets for the preservation or delay of cone loss are scarce. Recent findings have shown that excessive histone deacetylase (HDAC) activity is associated with both primary rod and primary cone degeneration. Importantly, pharmacological inhibition of HDAC activity in vivo at the onset of cone degeneration offers a prolonged protection of cones in a mouse model of inherited cone degeneration (cpfl1). In this study, we evaluated the potential of trichostatin A (TSA), a pan-HDAC inhibitor, to prevent cone cell death at a later stage of degeneration in the cpfl1 model. We demonstrate that a single intravitreal TSA injection protected the cpfl1 cones even when administered after the onset of degeneration. In addition, the TSA treatment significantly improved aberrant cone nucleokinesis present in the cpfl1 retina. These results highlight the feasibility of targeted cone neuroprotection in vivo even at later disease stages of inherited cone dystrophies.
Collapse
|
20
|
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.
Collapse
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
| | | |
Collapse
|
21
|
Fairchild CL, Hino K, Han JS, Miltner AM, Peinado Allina G, Brown CE, Burns ME, La Torre A, Simó S. RBX2 maintains final retinal cell position in a DAB1-dependent and -independent fashion. Development 2018; 145:dev.155283. [PMID: 29361558 DOI: 10.1242/dev.155283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 12/28/2017] [Indexed: 01/13/2023]
Abstract
The laminated structure of the retina is fundamental for the organization of the synaptic circuitry that translates light input into patterns of action potentials. However, the molecular mechanisms underlying cell migration and layering of the retina are poorly understood. Here, we show that RBX2, a core component of the E3 ubiquitin ligase CRL5, is essential for retinal layering and function. RBX2 regulates the final cell position of rod bipolar cells, cone photoreceptors and Muller glia. Our data indicate that sustained RELN/DAB1 signaling, triggered by depletion of RBX2 or SOCS7 - a CRL5 substrate adaptor known to recruit DAB1 - causes rod bipolar cell misposition. Moreover, whereas SOCS7 also controls Muller glia cell lamination, it is not responsible for cone photoreceptor positioning, suggesting that RBX2, most likely through CRL5 activity, controls other signaling pathways required for proper cone localization. Furthermore, RBX2 depletion reduces the number of ribbon synapses and disrupts cone photoreceptor function. Together, these results uncover RBX2 as a crucial molecular regulator of retina morphogenesis and cone photoreceptor function.
Collapse
Affiliation(s)
- Corinne L Fairchild
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Keiko Hino
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Jisoo S Han
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Adam M Miltner
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Gabriel Peinado Allina
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Caileigh E Brown
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Marie E Burns
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA.,Department of Ophthalmology and Vision Science, University of California Davis, CA 95616, USA
| | - Anna La Torre
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| | - Sergi Simó
- Department of Cell Biology and Human Anatomy, University of California Davis, CA 95616, USA
| |
Collapse
|
22
|
Trifunović D, Petridou E, Comitato A, Marigo V, Ueffing M, Paquet-Durand F. Primary Rod and Cone Degeneration Is Prevented by HDAC Inhibition. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:367-373. [PMID: 29721965 DOI: 10.1007/978-3-319-75402-4_45] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Photoreceptor cell death in inherited retinal degeneration is accompanied by over-activation of histone deacetylases (HDAC). Excessive HDAC activity is found both in primary rod degeneration (such as in the rd10 mouse) and in primary cone death, including the cone photoreceptor function loss 1 (cpfl1) mouse. We evaluated the potential of pharmacological HDAC inhibition to prevent photoreceptor degeneration in primary rod and cone degeneration. We show that a single in vivo treatment of cpfl1 mice with the HDAC inhibitor trichostatin A (TSA) resulted in a significant protection of cpfl1 mutant cones. Similarly, HDAC inhibition with the clinically approved HDAC inhibitor vorinostat (SAHA) resulted in a significant improvement of rod survival in rd10 retinal explant cultures. Altogether, these results highlight the feasibility of targeted neuroprotection in vivo and create hope to maintain vision in patients suffering from both rod and cone dystrophies.
Collapse
Affiliation(s)
- Dragana Trifunović
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany.
| | - Eleni Petridou
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Marius Ueffing
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | | |
Collapse
|
23
|
Maturation arrest in early postnatal sensory receptors by deletion of the miR-183/96/182 cluster in mouse. Proc Natl Acad Sci U S A 2017; 114:E4271-E4280. [PMID: 28484004 DOI: 10.1073/pnas.1619442114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The polycistronic miR-183/96/182 cluster is preferentially and abundantly expressed in terminally differentiating sensory epithelia. To clarify its roles in the terminal differentiation of sensory receptors in vivo, we deleted the entire gene cluster in mouse germline through homologous recombination. The miR-183/96/182 null mice display impairment of the visual, auditory, vestibular, and olfactory systems, attributable to profound defects in sensory receptor terminal differentiation. Maturation of sensory receptor precursors is delayed, and they never attain a fully differentiated state. In the retina, delay in up-regulation of key photoreceptor genes underlies delayed outer segment elongation and possibly mispositioning of cone nuclei in the retina. Incomplete maturation of photoreceptors is followed shortly afterward by early-onset degeneration. Cell biologic and transcriptome analyses implicate dysregulation of ciliogenesis, nuclear translocation, and an epigenetic mechanism that may control timing of terminal differentiation in developing photoreceptors. In both the organ of Corti and the vestibular organ, impaired terminal differentiation manifests as immature stereocilia and kinocilia on the apical surface of hair cells. Our study thus establishes a dedicated role of the miR-183/96/182 cluster in driving the terminal differentiation of multiple sensory receptor cells.
Collapse
|
24
|
Iribarne M, Nishiwaki Y, Nakamura S, Araragi M, Oguri E, Masai I. Aipl1 is required for cone photoreceptor function and survival through the stability of Pde6c and Gc3 in zebrafish. Sci Rep 2017; 7:45962. [PMID: 28378769 PMCID: PMC5381001 DOI: 10.1038/srep45962] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/07/2017] [Indexed: 12/18/2022] Open
Abstract
Genetic mutations in aryl hydrocarbon receptor interacting protein-like 1 (AIPL1) cause photoreceptor degeneration associated with Leber congenital amaurosis 4 (LCA4) in human patients. Here we report retinal phenotypes of a zebrafish aipl1 mutant, gold rush (gosh). In zebrafish, there are two aipl1 genes, aipl1a and aipl1b, which are expressed mainly in rods and cones, respectively. The gosh mutant gene encodes cone-specific aipl1, aipl1b. Cone photoreceptors undergo progressive degeneration in the gosh mutant, indicating that aipl1b is required for cone survival. Furthermore, the cone-specific subunit of cGMP phosphodiesterase 6 (Pde6c) is markedly decreased in the gosh mutant, and the gosh mutation genetically interacts with zebrafish pde6c mutation eclipse (els). These data suggest that Aipl1 is required for Pde6c stability and function. In addition to Pde6c, we found that zebrafish cone-specific guanylate cyclase, zGc3, is also decreased in the gosh and els mutants. Furthermore, zGc3 knockdown embryos showed a marked reduction in Pde6c. These observations illustrate the interdependence of cGMP metabolism regulators between Aipl1, Pde6c, and Gc3 in photoreceptors.
Collapse
Affiliation(s)
- Maria Iribarne
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Yuko Nishiwaki
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Shohei Nakamura
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Masato Araragi
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Eri Oguri
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Ichiro Masai
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| |
Collapse
|
25
|
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.
Collapse
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
| | | |
Collapse
|
26
|
Jimeno D, Santos E. A new functional role uncovered for RASGRF2 in control of nuclear migration in cone photoreceptors during postnatal retinal development. Small GTPases 2016; 8:26-30. [PMID: 27221061 DOI: 10.1080/21541248.2016.1189989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Despite their homologous structure and central nervous system(CNS) expression patterns, the GRF1 and GRF2 guanine nucleotide exchange factors(GEF) appear to play distinct, non-overlapping functions in cellular excitability, synaptic plasticity or neuromodulation. We recently uncovered a new functional role of GRF2 controlling nuclear migration in cone photoreceptors during postnatal neuroepithelial differentiation of the mouse retina. Analyzing GRF2-KO mice, we detected the specific accumulation of abnormally located, "ectopic" cone photoreceptor nuclei in the photoreceptor segment(PS) layer of their retinas. This alteration was accompanied by defective electroretinograms(ERG) indicative of impaired cone-mediated visual function, and accumulation around the "ectopic" nuclei of signaling molecules known to be functionally relevant for intracellular organelle migration, cytoskeletal reorganization or cell polarity establishment including PAR3, PAR6, and the phosphorylated proteins pPAK, pMLC2 and pVASP. We propose a mechanism whereby the absence of a productive functional interaction between GRF2 and its downstream target CDC42 leads to altered formation/structure of PAR-containing, polarity-related macromolecular complexes and abnormal activation of downstream signaling mediated by activated, phosphorylated forms of PAK, VASP and MLC2. As cone photoreceptors are responsible for color vision and visual acuity, these observations are potentially relevant for degenerative diseases of the human retina, harboring almost double number of cones than mice.
Collapse
Affiliation(s)
- David Jimeno
- a Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) , Salamanca , Spain
| | - Eugenio Santos
- a Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC- Universidad de Salamanca) , Salamanca , Spain
| |
Collapse
|
27
|
Comitato A, Di Salvo MT, Turchiano G, Montanari M, Sakami S, Palczewski K, Marigo V. Dominant and recessive mutations in rhodopsin activate different cell death pathways. Hum Mol Genet 2016; 25:2801-2812. [PMID: 27149983 DOI: 10.1093/hmg/ddw137] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/05/2016] [Accepted: 04/25/2016] [Indexed: 12/25/2022] Open
Abstract
Mutations in rhodopsin (RHO) are a common cause of retinal dystrophy and can be transmitted by dominant or recessive inheritance. Clinical symptoms caused by dominant and recessive mutations in patients and animal models are very similar but the molecular mechanisms leading to retinal degeneration may differ. We characterized three murine models of retina degeneration caused by either Rho loss of function or expression of the P23H dominant mutation in Rho. Rho loss of function is characterized by activation of calpains and apoptosis-inducing factor (Aif) in dying photoreceptors. Retinas bearing the P23H dominant mutations activate both the calpain-Aif cell death pathway and ER-stress responses that together contribute to photoreceptor cell demise. In vivo treatment with the calpastatin peptide, a calpain inhibitor, was strongly neuroprotective in mice lacking Rho while photoreceptor survival in retinas expressing the P23H dominant mutation was more affected by treatment with salubrinal, an inhibitor of the ER-stress pathway. The further reduction of photoreceptor cell demise by co-treatment with calpastatin and salubrinal suggests co-activation of the calpain and ER-stress death pathways in mice bearing dominant mutations in the Rho gene.
Collapse
Affiliation(s)
- Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Maria Teresa Di Salvo
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Giandomenico Turchiano
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Monica Montanari
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Sanae Sakami
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| |
Collapse
|
28
|
Jimeno D, Gómez C, Calzada N, de la Villa P, Lillo C, Santos E. RASGRF2 controls nuclear migration in postnatal retinal cone photoreceptors. J Cell Sci 2016; 129:729-42. [PMID: 26743081 DOI: 10.1242/jcs.180919] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/29/2015] [Indexed: 02/04/2023] Open
Abstract
Detailed immunocytochemical analyses comparing wild-type (WT), GRF1-knockout (KO), GRF2-KO and GRF1/2 double-knockout (DKO) mouse retinas uncovered the specific accumulation of misplaced, 'ectopic' cone photoreceptor nuclei in the photoreceptor segment (PS) area of retinas from GRF2-KO and GRF1/2-DKO, but not of WT or GRF1-KO mice. Localization of ectopic nuclei in the PS area of GRF2-depleted retinas occurred postnatally and peaked between postnatal day (P)11 and P15. Mechanistically, the generation of this phenotype involved disruption of the outer limiting membrane and intrusion into the PS layer by cone nuclei displaying significant perinuclear accumulation of signaling molecules known to participate in nuclear migration and cytoskeletal reorganization, such as PAR3, PAR6 and activated, phosphorylated forms of PAK, MLC2 and VASP. Electroretinographic recordings showed specific impairment of cone-mediated retinal function in GRF2-KO and GRF1/2-DKO retinas compared with WT controls. These data identify defective cone nuclear migration as a novel phenotype in mouse retinas lacking GRF2 and support a crucial role of GRF2 in control of the nuclear migration processes required for proper postnatal development and function of retinal cone photoreceptors.
Collapse
Affiliation(s)
- David Jimeno
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC - Universidad de Salamanca), Salamanca 37007, Spain
| | - Carmela Gómez
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC - Universidad de Salamanca), Salamanca 37007, Spain
| | - Nuria Calzada
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC - Universidad de Salamanca), Salamanca 37007, Spain
| | - Pedro de la Villa
- Departamento de Fisiología, Universidad Alcalá, Alcalá de Henares 28871, Spain, Spain
| | | | - Eugenio Santos
- Centro de Investigación del Cáncer-Instituto de Biología Molecular y Celular del Cáncer (CSIC - Universidad de Salamanca), Salamanca 37007, Spain
| |
Collapse
|
29
|
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]
|
30
|
Rax Homeoprotein Regulates Photoreceptor Cell Maturation and Survival in Association with Crx in the Postnatal Mouse Retina. Mol Cell Biol 2015; 35:2583-96. [PMID: 25986607 DOI: 10.1128/mcb.00048-15] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 05/10/2015] [Indexed: 12/11/2022] Open
Abstract
The Rax homeobox gene plays essential roles in multiple processes of vertebrate retina development. Many vertebrate species possess Rax and Rax2 genes, and different functions have been suggested. In contrast, mice contain a single Rax gene, and its functional roles in late retinal development are still unclear. To clarify mouse Rax function in postnatal photoreceptor development and maintenance, we generated conditional knockout mice in which Rax in maturing or mature photoreceptor cells was inactivated by tamoxifen treatment (Rax iCKO mice). When Rax was inactivated in postnatal Rax iCKO mice, developing photoreceptor cells showed a significant decrease in the level of the expression of rod and cone photoreceptor genes and mature adult photoreceptors exhibited a specific decrease in cone cell numbers. In luciferase assays, we found that Rax and Crx cooperatively transactivate Rhodopsin and cone opsin promoters and that an optimum Rax expression level to transactivate photoreceptor gene expression exists. Furthermore, Rax and Crx colocalized in maturing photoreceptor cells, and their coimmunoprecipitation was observed in cultured cells. Taken together, these results suggest that Rax plays essential roles in the maturation of both cones and rods and in the survival of cones by regulating photoreceptor gene expression with Crx in the postnatal mouse retina.
Collapse
|
31
|
Kulkarni M, Schubert T, Baden T, Wissinger B, Euler T, Paquet-Durand F. Imaging Ca2+ dynamics in cone photoreceptor axon terminals of the mouse retina. J Vis Exp 2015:e52588. [PMID: 25993489 PMCID: PMC4542458 DOI: 10.3791/52588] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Retinal cone photoreceptors (cones) serve daylight vision and are the basis of color discrimination. They are subject to degeneration, often leading to blindness in many retinal diseases. Calcium (Ca2+), a key second messenger in photoreceptor signaling and metabolism, has been proposed to be indirectly linked with photoreceptor degeneration in various animal models. Systematically studying these aspects of cone physiology and pathophysiology has been hampered by the difficulties of electrically recording from these small cells, in particular in the mouse where the retina is dominated by rod photoreceptors. To circumvent this issue, we established a two-photon Ca2+ imaging protocol using a transgenic mouse line that expresses the genetically encoded Ca2+ biosensor TN-XL exclusively in cones and can be crossbred with mouse models for photoreceptor degeneration. The protocol described here involves preparing vertical sections (“slices”) of retinas from mice and optical imaging of light stimulus-evoked changes in cone Ca2+ level. The protocol also allows “in-slice measurement” of absolute Ca2+ concentrations; as the recordings can be followed by calibration. This protocol enables studies into functional cone properties and is expected to contribute to the understanding of cone Ca2+ signaling as well as the potential involvement of Ca2+ in photoreceptor death and retinal degeneration.
Collapse
Affiliation(s)
- Manoj Kulkarni
- Institute for Ophthalmic Research, University of Tübingen; Graduate School of Cellular & Molecular Neuroscience, University of Tübingen
| | - Timm Schubert
- Institute for Ophthalmic Research, University of Tübingen; Bernstein Centre for Computational Neuroscience, University of Tübingen
| | - Tom Baden
- Institute for Ophthalmic Research, University of Tübingen; Graduate School of Cellular & Molecular Neuroscience, University of Tübingen; Bernstein Centre for Computational Neuroscience, University of Tübingen
| | - Bernd Wissinger
- Molecular Genetics Laboratory, University of Tübingen; Centre for Ophthalmology, University of Tübingen
| | - Thomas Euler
- Institute for Ophthalmic Research, University of Tübingen; Graduate School of Cellular & Molecular Neuroscience, University of Tübingen; Bernstein Centre for Computational Neuroscience, University of Tübingen;
| | | |
Collapse
|
32
|
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.
Collapse
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
| | | |
Collapse
|
33
|
Samardzija M, Grimm C. Mouse models for cone degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:567-73. [PMID: 24664745 DOI: 10.1007/978-1-4614-3209-8_72] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Loss of cone vision has devastating effects on everyday life. Even though much effort has been made to understand cone physiology and pathophysiology, no successful therapies are available for patients suffering from cone disorders. As complex retinal interactions cannot be studied in vitro, utilization of different animal models is inevitable. Due to recent advances in transgenesis, mice became the most popular animal model to study human diseases, also in ophthalmology. While there are similarities in retinal anatomy and pathophysiology between mice and humans, there are also differences, most importantly the lack of a cone-rich macula in mice. Instead, cones in mice are rare and distributed over the whole retina, which makes the analysis of cone pathophysiology very difficult in these animals. This hindrance is one of the reasons why our understanding of rod pathophysiological processes is much more advanced. Recently, however, the sparseness of cones was overcome by the generation of the Nrl (- / -) mouse that expresses only cone photoreceptors in the retina. This paper will give a brief overview of some of the known mouse models to study cone degeneration and discuss the current knowledge gained from the analysis of these models.
Collapse
Affiliation(s)
- Marijana Samardzija
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Wagistr 14 Schlieren, 8952, Zurich, Switzerland,
| | | |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- F Paquet-Durand
- François Paquet-Durand, Institute for Ophthalmic Research, University of Tübingen, Röntgenweg 11, 72076, Tübingen, Germany,
| | | | | | | | | | | | | |
Collapse
|
35
|
Loss of Pde6 reduces cell body Ca(2+) transients within photoreceptors. Cell Death Dis 2013; 4:e797. [PMID: 24030149 PMCID: PMC3789190 DOI: 10.1038/cddis.2013.332] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 07/21/2013] [Accepted: 07/29/2013] [Indexed: 11/30/2022]
Abstract
Modulation of Ca2+ within cells is tightly regulated through complex and dynamic interactions between the plasma membrane and internal compartments. In this study, we exploit in vivo imaging strategies based on genetically encoded Ca2+ indicators to define changes in perikaryal Ca2+ concentration of intact photoreceptors. We developed double-transgenic zebrafish larvae expressing GCaMP3 in all cones and tdTomato in long-wavelength cones to test the hypothesis that photoreceptor degeneration induced by mutations in the phosphodiesterase-6 (Pde6) gene is driven by excessive [Ca2+]i levels within the cell body. Arguing against Ca2+ overload in Pde6 mutant photoreceptors, simultaneous analysis of cone photoreceptor morphology and Ca2+ fluxes revealed that degeneration of pde6cw59 mutant cones, which lack the cone-specific cGMP phosphodiesterase, is not associated with sustained increases in perikaryal [Ca2+]i. Analysis of [Ca2+]i in dissociated Pde6βrd1mouse rods shows conservation of this finding across vertebrates. In vivo, transient and Pde6-independent Ca2+ elevations (‘flashes') were detected throughout the inner segment and the synapse. As the mutant cells proceeded to degenerate, these Ca2+ fluxes diminished. This study thus provides insight into Ca2+ dynamics in a common form of inherited blindness and uncovers a dramatic, light-independent modulation of [Ca2+]i that occurs in normal cones.
Collapse
|
36
|
Cho KI, Haque M, Wang J, Yu M, Hao Y, Qiu S, Pillai ICL, Peachey NS, Ferreira PA. Distinct and atypical intrinsic and extrinsic cell death pathways between photoreceptor cell types upon specific ablation of Ranbp2 in cone photoreceptors. PLoS Genet 2013; 9:e1003555. [PMID: 23818861 PMCID: PMC3688534 DOI: 10.1371/journal.pgen.1003555] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 04/23/2013] [Indexed: 12/26/2022] Open
Abstract
Non-autonomous cell-death is a cardinal feature of the disintegration of neural networks in neurodegenerative diseases, but the molecular bases of this process are poorly understood. The neural retina comprises a mosaic of rod and cone photoreceptors. Cone and rod photoreceptors degenerate upon rod-specific expression of heterogeneous mutations in functionally distinct genes, whereas cone-specific mutations are thought to cause only cone demise. Here we show that conditional ablation in cone photoreceptors of Ran-binding protein-2 (Ranbp2), a cell context-dependent pleiotropic protein linked to neuroprotection, familial necrotic encephalopathies, acute transverse myelitis and tumor-suppression, promotes early electrophysiological deficits, subcellular erosive destruction and non-apoptotic death of cones, whereas rod photoreceptors undergo cone-dependent non-autonomous apoptosis. Cone-specific Ranbp2 ablation causes the temporal activation of a cone-intrinsic molecular cascade highlighted by the early activation of metalloproteinase 11/stromelysin-3 and up-regulation of Crx and CoREST, followed by the down-modulation of cone-specific phototransduction genes, transient up-regulation of regulatory/survival genes and activation of caspase-7 without apoptosis. Conversely, PARP1+-apoptotic rods develop upon sequential activation of caspase-9 and caspase-3 and loss of membrane permeability. Rod photoreceptor demise ceases upon cone degeneration. These findings reveal novel roles of Ranbp2 in the modulation of intrinsic and extrinsic cell death mechanisms and pathways. They also unveil a novel spatiotemporal paradigm of progression of neurodegeneration upon cell-specific genetic damage whereby a cone to rod non-autonomous death pathway with intrinsically distinct cell-type death manifestations is triggered by cell-specific loss of Ranbp2. Finally, this study casts new light onto cell-death mechanisms that may be shared by human dystrophies with distinct retinal spatial signatures as well as with other etiologically distinct neurodegenerative disorders. The secondary demise of healthy neurons upon the degeneration of neurons harboring primary genetic defect(s) is hallmark to neurodegenerative diseases. However, the factors and mechanisms driving these cell-death processes are not understood, a severe limitation which has hampered the therapeutic development of neuroprotective approaches. The neuroretina is comprised of two main types of photoreceptor neurons, rods and cones. These undergo degeneration upon heterogeneous mutations or environmental stressors and the underlying diseases present conspicuous spatiotemporal pathological signatures whose molecular bases are not understood. We employed the multifunctional protein, Ran-binding protein-2 (Ranbp2), which is implicated in cell-type and stress-dependent clinical manifestations, to examine its role(s) in primary and secondary photoreceptor death mechanisms upon its specific loss in cones. Contrary to prior findings, we found that dying cones can trigger the loss of healthy rods. This process arises by the immediate activation of novel Ranbp2-responsive factors and downstream cascade events in cones that promote extrinsically the demise of rods. The mechanisms of rod and cone demise are molecularly distinct. Collectively, the data uncover distinct Ranbp2 roles in intrinsic and extrinsic cell-death and will likely contribute to our understanding of the spatiotemporal onset and progression of diseases affecting photoreceptor mosaics and other neural networks.
Collapse
Affiliation(s)
- Kyoung-in Cho
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - MdEmdadul Haque
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jessica Wang
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
| | - Ying Hao
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sunny Qiu
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Indulekha C. L. Pillai
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Research Service, Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Paulo A. Ferreira
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pathology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
37
|
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.
Collapse
|
38
|
LINC complexes mediate the positioning of cone photoreceptor nuclei in mouse retina. PLoS One 2012; 7:e47180. [PMID: 23071752 PMCID: PMC3465324 DOI: 10.1371/journal.pone.0047180] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 09/10/2012] [Indexed: 11/19/2022] Open
Abstract
It has long been observed that many neuronal types position their nuclei within restricted cytoplasmic boundaries. A striking example is the apical localization of cone photoreceptors nuclei at the outer edge of the outer nuclear layer of mammalian retinas. Yet, little is known about how such nuclear spatial confinement is achieved and further maintained. Linkers of the Nucleoskeleton to the Cytoskeleton (LINC complexes) consist of evolutionary-conserved macromolecular assemblies that span the nuclear envelope to connect the nucleus with the peripheral cytoskeleton. Here, we applied a new transgenic strategy to disrupt LINC complexes either in cones or rods. In adult cones, we observed a drastic nuclear mislocalization on the basal side of the ONL that affected cone terminals overall architecture. We further provide evidence that this phenotype may stem from the inability of cone precursor nuclei to migrate towards the apical side of the outer nuclear layer during early postnatal retinal development. By contrast, disruption of LINC complexes within rod photoreceptors, whose nuclei are scattered across the outer nuclear layer, had no effect on the positioning of their nuclei thereby emphasizing differential requirements for LINC complexes by different neuronal types. We further show that Sun1, a component of LINC complexes, but not A-type lamins, which interact with LINC complexes at the nuclear envelope, participate in cone nuclei positioning. This study provides key mechanistic aspects underlying the well-known spatial confinement of cone nuclei as well as a new mouse model to evaluate the pathological relevance of nuclear mispositioning.
Collapse
|
39
|
Abstract
Calcium mediates various neuronal functions. The complexity of neuronal Ca²⁺ signaling is well exemplified by retinal cone photoreceptors, which, with their distinct compartmentalization, offer unique possibilities for studying the diversity of Ca²⁺ functions in a single cell. Measuring subcellular Ca²⁺ signals in cones under physiological conditions is not only fundamental for understanding cone function, it also bears important insights into pathophysiological processes governing retinal neurodegeneration. However, due to the proximity of light-sensitive outer segments to other cellular compartments, optical measurements of light-evoked Ca²⁺ responses in cones are challenging. We addressed this problem by generating a transgenic mouse (HR2.1:TN-XL) in which both short- and middle-wavelength-sensitive cones selectively express the genetically encoded ratiometric Ca²⁺ biosensor TN-XL. We show that HR2.1:TN-XL allows recording of light-evoked Ca²⁺ responses using two-photon imaging in individual cone photoreceptor terminals and to probe phototransduction and its diverse regulatory mechanisms with pharmacology at subcellular resolution. To further test this system, we asked whether the classical, nitric oxide (NO)-soluble guanylyl-cyclase (sGC)-cGMP pathway could modulate Ca²⁺ in cone terminals. Surprisingly, NO reduced Ca²⁺ resting levels in mouse cones, without evidence for direct sGC involvement. In conclusion, HR2.1:TN-XL mice offer unprecedented opportunities to elucidate light-driven Ca²⁺ dynamics and their (dys)regulation in cone photoreceptors.
Collapse
|
40
|
Kirk SR, Andrade AL, Melich K, Jackson EP, Cuellar E, Karpen JW. Halogen substituents on the aromatic moiety of the tetracaine scaffold improve potency of cyclic nucleotide-gated channel block. Bioorg Med Chem Lett 2011; 21:6417-9. [DOI: 10.1016/j.bmcl.2011.08.092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Accepted: 08/19/2011] [Indexed: 11/28/2022]
|
41
|
Kolandaivelu S, Chang B, Ramamurthy V. Rod phosphodiesterase-6 (PDE6) catalytic subunits restore cone function in a mouse model lacking cone PDE6 catalytic subunit. J Biol Chem 2011; 286:33252-9. [PMID: 21799013 DOI: 10.1074/jbc.m111.259101] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Rod and cone photoreceptor neurons utilize discrete PDE6 enzymes that are crucial for phototransduction. Rod PDE6 is composed of heterodimeric catalytic subunits (αβ), while the catalytic core of cone PDE6 (α') is a homodimer. It is not known if variations between PDE6 subunits preclude rod PDE6 catalytic subunits from coupling to the cone phototransduction pathway. To study this issue, we generated a cone-dominated mouse model lacking cone PDE6 (Nrl(-/-) cpfl1). In this animal model, using several independent experimental approaches, we demonstrated the expression of rod PDE6 (αβ) and the absence of cone PDE6 (α') catalytic subunits. The rod PDE6 enzyme expressed in cone cells is active and contributes to the hydrolysis of cGMP in response to light. In addition, rod PDE6 expressed in cone cells couples to the light signaling pathway to produce S-cone responses. However, S-cone responses and light-dependent cGMP hydrolysis were eliminated when the β-subunit of rod PDE6 was removed (Nrl(-/-) cpfl1 rd). We conclude that either rod or cone PDE6 can effectively couple to the cone phototransduction pathway to mediate visual signaling. Interestingly, we also found that functional PDE6 is required for trafficking of M-opsin to cone outer segments.
Collapse
Affiliation(s)
- Saravanan Kolandaivelu
- Departments of Ophthalmology and Biochemistry, Center for Neuroscience, West Virginia University, Morgantown, West Virginia 26506, USA
| | | | | |
Collapse
|
42
|
Andrade AL, Melich K, Whatley GG, Kirk SR, Karpen JW. Cyclic nucleotide-gated channel block by hydrolysis-resistant tetracaine derivatives. J Med Chem 2011; 54:4904-12. [PMID: 21634421 DOI: 10.1021/jm200495g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To meet a pressing need for better cyclic nucleotide-gated (CNG) channel antagonists, we have increased the biological stability of tetracaine-based blockers by synthesizing amide and thioamide linkage substitutions of tetracaine (1) and a higher affinity octyl tail derivative (5). We report the apparent K(D) values, the mechanism of block, and the in vitro hydrolysis rates for these compounds. The ester linkage substitutions did not adversely affect CNG channel block; unexpectedly, thioamide substitution in 1 (compound 8) improved block significantly. Furthermore, the ester linkage substitutions did not appear to affect the mechanism of block in terms of the strong state preference for closed channels. All ester substituted compounds, especially the thioamide substitutions, were more resistant to hydrolysis by serum cholinesterase than their ester counterparts. These findings have implications for dissecting the physiological roles of CNG channels, treating certain forms of retinal degeneration, and possibly the current clinical uses of compound 1.
Collapse
Affiliation(s)
- Adriana L Andrade
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239, United States
| | | | | | | | | |
Collapse
|
43
|
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: 84] [Impact Index Per Article: 6.0] [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.
Collapse
Affiliation(s)
- François Paquet-Durand
- Division of Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Röntgenweg 11, 72076 Tübingen, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|