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Caminos E, López-López S, Martinez-Galan JR. Selective Assembly of TRPC Channels in the Rat Retina during Photoreceptor Degeneration. Int J Mol Sci 2024; 25:7251. [PMID: 39000357 PMCID: PMC11242081 DOI: 10.3390/ijms25137251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/16/2024] Open
Abstract
Transient receptor potential canonical (TRPC) channels are calcium channels with diverse expression profiles and physiological implications in the retina. Neurons and glial cells of rat retinas with photoreceptor degeneration caused by retinitis pigmentosa (RP) exhibit basal calcium levels that are above those detected in healthy retinas. Inner retinal cells are the last to degenerate and are responsible for maintaining the activity of the visual cortex, even after complete loss of photoreceptors. We considered the possibility that TRPC1 and TRPC5 channels might be associated with both the high calcium levels and the delay in inner retinal degeneration. TRPC1 is known to mediate protective effects in neurodegenerative processes while TRPC5 promotes cell death. In order to comprehend the implications of these channels in RP, the co-localization and subsequent physical interaction between TRPC1 and TRPC5 in healthy retina (Sprague-Dawley rats) and degenerating (P23H-1, a model of RP) retina were detected by immunofluorescence and proximity ligation assays. There was an overlapping signal in the innermost retina of all animals where TRPC1 and TRPC5 physically interacted. This interaction increased significantly as photoreceptor loss progressed. Both channels function as TRPC1/5 heteromers in the healthy and damaged retina, with a marked function of TRPC1 in response to retinal degenerative mechanisms. Furthermore, our findings support that TRPC5 channels also function in partnership with STIM1 in Müller and retinal ganglion cells. These results suggest that an increase in TRPC1/5 heteromers may contribute to the slowing of the degeneration of the inner retina during the outer retinal degeneration.
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Affiliation(s)
- Elena Caminos
- Department of Medical Science, Medical School of Albacete, Instituto de Biomedicina (IB-UCLM), University of Castilla-La Mancha, 02008 Albacete, Spain
| | - Susana López-López
- Department of Medical Science, Medical School of Albacete, Instituto de Biomedicina (IB-UCLM), University of Castilla-La Mancha, 02008 Albacete, Spain
- Consejo Superior de Investigaciones Científicas, and Research Unit, Complejo Hospitalario Universitario de Albacete, 02008 Albacete, Spain
| | - Juan R Martinez-Galan
- Department of Medical Science, Medical School of Albacete, Instituto de Biomedicina (IB-UCLM), University of Castilla-La Mancha, 02008 Albacete, Spain
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2
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Kamal NM, Gorafi YSA, Tomemori H, Kim JS, Elhadi GMI, Tsujimoto H. Genetic variation for grain nutritional profile and yield potential in sorghum and the possibility of selection for drought tolerance under irrigated conditions. BMC Genomics 2023; 24:515. [PMID: 37660014 PMCID: PMC10474746 DOI: 10.1186/s12864-023-09613-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/22/2023] [Indexed: 09/04/2023] Open
Abstract
BACKGROUND Increasing grain nutritional value in sorghum (Sorghum bicolor) is a paramount breeding objective, as is increasing drought resistance (DR), because sorghum is grown mainly in drought-prone areas. The genetic basis of grain nutritional traits remains largely unknown. Marker-assisted selection using significant loci identified through genome-wide association study (GWAS) shows potential for selecting desirable traits in crops. This study assessed natural variation available in sorghum accessions from around the globe to identify novel genes or genomic regions with potential for improving grain nutritional value, and to study associations between DR traits and grain weight and nutritional composition. RESULTS We dissected the genetic architecture of grain nutritional composition, protein content, thousand-kernel weight (TKW), and plant height (PH) in sorghum through GWAS of 163 unique African and Asian accessions under irrigated and post-flowering drought conditions. Several QTLs were detected. Some were significantly associated with DR, TKW, PH, protein, and Zn, Mn, and Ca contents. Genomic regions on chromosomes 1, 2, 4, 8, 9, and 10 were associated with TKW, nutritional, and DR traits; colocalization patterns of these markers indicate potential for simultaneous improvement of these traits. In African accessions, markers associated with TKW were mapped to six regions also associated with protein, Zn, Ca, Mn, Na, and DR, suggesting the potential for simultaneous selection for higher grain nutrition and TKW. Our results indicate that it may be possible to select for increased DR on the basis of grain nutrition and weight potential. CONCLUSIONS This study provides a valuable resource for selecting landraces for use in plant breeding programs and for identifying loci that may contribute to grain nutrition and weight with the hope of producing cultivars that combine improved yield traits, nutrition, and DR.
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Affiliation(s)
- Nasrein Mohamed Kamal
- Arid Land Research Center, Tottori University, Tottori, 680-0001, Japan.
- Agricultural Research Corporation, PO Box 126, Wad Medani, Sudan.
| | - Yasir Serag Alnor Gorafi
- Agricultural Research Corporation, PO Box 126, Wad Medani, Sudan
- International Platform for Dryland Research and Education, Tottori University, Tottori, Japan
| | - Hisashi Tomemori
- Arid Land Research Center, Tottori University, Tottori, 680-0001, Japan
| | - June-Sik Kim
- RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | | | - Hisashi Tsujimoto
- Arid Land Research Center, Tottori University, Tottori, 680-0001, Japan.
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Grini JV, Nygård M, Ruoff P. Homeostasis at different backgrounds: The roles of overlayed feedback structures in vertebrate photoadaptation. PLoS One 2023; 18:e0281490. [PMID: 37115760 PMCID: PMC10146485 DOI: 10.1371/journal.pone.0281490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 03/30/2023] [Indexed: 04/29/2023] Open
Abstract
We have studied the resetting behavior of eight basic integral controller motifs with respect to different but constant backgrounds. We found that the controllers split symmetrically into two classes: one class, based on derepression of the compensatory flux, leads to more rapid resetting kinetics as backgrounds increase. The other class, which directly activates the compensatory flux, shows a slowing down in the resetting at increased backgrounds. We found a striking analogy between the resetting kinetics of vertebrate photoreceptors and controllers based on derepression, i.e. vertebrate rod or cone cells show decreased sensitivities and accelerated response kinetics as background illuminations increase. The central molecular model of vertebrate photoadaptation consists of an overlay of three negative feedback loops with cytosolic calcium ([Formula: see text]), cyclic guanosine monophosphate (cGMP) and cyclic nucleotide-gated (CNG) channels as components. While in one of the feedback loops the extrusion of [Formula: see text] by potassium-dependent sodium-calcium exchangers (NCKX) can lead to integral control with cGMP as the controlled variable, the expected robust perfect adaptation of cGMP is lost, because of the two other feedback loops. They avoid that [Formula: see text] levels become too high and toxic. Looking at psychophysical laws, we found that in all of the above mentioned basic controllers Weber's law is followed when a "just noticeable difference" (threshold) of 1% of the controlled variable's set-point was considered. Applying comparable threshold pulses or steps to the photoadaptation model we find, in agreement with experimental results, that Weber's law is followed for relatively high backgrounds, while Stephens' power law gives a better description when backgrounds are low. Limitations of our photoadaption model, in particular with respect to potassium/sodium homeostasis, are discussed. Finally, we discuss possible implication of background perturbations in biological controllers when compensatory fluxes are based on activation.
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Affiliation(s)
- Jonas V Grini
- Department of Chemistry, Bioscience, and Environmental Engineering, University of Stavanger, Stavanger, Norway
| | - Melissa Nygård
- Department of Chemistry, Bioscience, and Environmental Engineering, University of Stavanger, Stavanger, Norway
| | - Peter Ruoff
- Department of Chemistry, Bioscience, and Environmental Engineering, University of Stavanger, Stavanger, Norway
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Martínez-Gil N, Maneu V, Kutsyr O, Fernández-Sánchez L, Sánchez-Sáez X, Sánchez-Castillo C, Campello L, Lax P, Pinilla I, Cuenca N. Cellular and molecular alterations in neurons and glial cells in inherited retinal degeneration. Front Neuroanat 2022; 16:984052. [PMID: 36225228 PMCID: PMC9548552 DOI: 10.3389/fnana.2022.984052] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/29/2022] [Indexed: 11/19/2022] Open
Abstract
Multiple gene mutations have been associated with inherited retinal dystrophies (IRDs). Despite the spectrum of phenotypes caused by the distinct mutations, IRDs display common physiopathology features. Cell death is accompanied by inflammation and oxidative stress. The vertebrate retina has several attributes that make this tissue vulnerable to oxidative and nitrosative imbalance. The high energy demands and active metabolism in retinal cells, as well as their continuous exposure to high oxygen levels and light-induced stress, reveal the importance of tightly regulated homeostatic processes to maintain retinal function, which are compromised in pathological conditions. In addition, the subsequent microglial activation and gliosis, which triggers the secretion of pro-inflammatory cytokines, chemokines, trophic factors, and other molecules, further worsen the degenerative process. As the disease evolves, retinal cells change their morphology and function. In disease stages where photoreceptors are lost, the remaining neurons of the retina to preserve their function seek out for new synaptic partners, which leads to a cascade of morphological alterations in retinal cells that results in a complete remodeling of the tissue. In this review, we describe important molecular and morphological changes in retinal cells that occur in response to oxidative stress and the inflammatory processes underlying IRDs.
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Affiliation(s)
- Natalia Martínez-Gil
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Oksana Kutsyr
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | | | - Xavier Sánchez-Sáez
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Carla Sánchez-Castillo
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
- Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain
| | - Isabel Pinilla
- Aragón Institute for Health Research (IIS Aragón), Zaragoza, Spain
- Department of Ophthalmology, Lozano Blesa University Hospital, Zaragoza, Spain
- Department of Surgery, University of Zaragoza, Zaragoza, Spain
- Isabel Pinilla,
| | - Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
- Alicante Institute for Health and Biomedical Research (ISABIAL), Alicante, Spain
- Institute Ramón Margalef, University of Alicante, Alicante, Spain
- *Correspondence: Nicolás Cuenca,
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Kazmierczak de Camargo JP, Prezia GNDB, Shiokawa N, Sato MT, Rosati R, Beate Winter Boldt A. New Insights on the Regulatory Gene Network Disturbed in Central Areolar Choroidal Dystrophy-Beyond Classical Gene Candidates. Front Genet 2022; 13:886461. [PMID: 35656327 PMCID: PMC9152281 DOI: 10.3389/fgene.2022.886461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Central areolar choroidal dystrophy (CACD) is a rare hereditary disease that mainly affects the macula, resulting in progressive and usually profound visual loss. Being part of congenital retinal dystrophies, it may have an autosomal dominant or recessive inheritance and, until now, has no effective treatment. Given the shortage of genotypic information about the disease, this work systematically reviews the literature for CACD-causing genes. Three independent researchers selected 33 articles after carefully searching and filtering the Scielo, Pubmed, Lilacs, Web of Science, Scopus, and Embase databases. Mutations of six genes (PRPH2, GUCA1A, GUCY2D, CDHR1, ABCA4, and TTLL5) are implicated in the monogenic dominant inheritance of CACD. They are functionally related to photoreceptors (either in the phototransduction process, as in the case of GUCY2D, or the recovery of retinal photodegradation in photoreceptors for GUCA1A, or the formation and maintenance of specific structures within photoreceptors for PRPH2). The identified genetic variants do not explain all observed clinical features, calling for further whole-genome and functional studies for this disease. A network analysis with the CACD-related genes identified in the systematic review resulted in the identification of another 20 genes that may influence CACD onset and symptoms. Furthermore, an enrichment analysis allowed the identification of 13 transcription factors and 4 long noncoding RNAs interacting with the products of the previously mentioned genes. If mutated or dysregulated, they may be directly involved in CACD development and related disorders. More than half of the genes identified by bioinformatic tools do not appear in commercial gene panels, calling for more studies about their role in the maintenance of the retina and phototransduction process, as well as for a timely update of these gene panels.
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Affiliation(s)
| | - Giovanna Nazaré de Barros Prezia
- Post-Graduation Program in Biotechnology Applied to Child and Adolescent Health, Faculdades Pequeno Príncipe and Pelé Pequeno Príncipe Research Institute, Curitiba, Brazil
| | - Naoye Shiokawa
- Retina and Vitreo Consulting Eye Clinic, Curitiba, Brazil
| | - Mario Teruo Sato
- Retina and Vitreo Consulting Eye Clinic, Curitiba, Brazil.,Department of Ophthalmol/Otorhinolaryngology, Federal University of Paraná, Curitiba, Brazil
| | - Roberto Rosati
- Post-Graduation Program in Biotechnology Applied to Child and Adolescent Health, Faculdades Pequeno Príncipe and Pelé Pequeno Príncipe Research Institute, Curitiba, Brazil
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6
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Hay AC, Sandoval-Castillo J, Cooke GM, Chao NL, Beheregaray LB. Riverscape Genomics Clarifies Neutral and Adaptive Evolution in an Amazonian Characin Fish (Triportheus albus). Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.825406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Understanding the role of natural selection in the evolution of wild populations is challenging due to the spatial complexity of natural systems. The richest diversity of freshwater fishes in the world is found in the Amazon Basin, a system where marked hydrochemical differences exist at the interface of major rivers with distinct “water colors” (i.e., black, white, and clear water). We hypothesize that divergent natural selection associated with these “aquatic ecotones” influences population-level adaptive divergence in the non-migratory Amazonian fish fauna. This hypothesis was tested using a landscape genomics framework to compare the relative contribution of environmental and spatial factors to the evolutionary divergence of the Amazonian characin fish Triportheus albus. The framework was based on spatial data, in situ hydrochemical measurements, and 15,251 filtered SNPs (single nucleotide polymorphisms) for T. albus sampled from three major Amazonian rivers. Gradient Forest, redundancy analysis (RDA) and BayPass analyses were used to test for signals of natural selection, and model-based and model-free approaches were used to evaluate neutral population differentiation. After controlling for a signal of neutral hierarchical structure which was consistent with the expectations for a dendritic system, variation in turbidity and pH were key factors contributing to adaptive divergence. Variation in genes involved in acid-sensitive ion transport pathways and light-sensitive photoreceptor pathways was strongly associated with pH and turbidity variability. This study improves our understanding of how natural selection and neutral evolution impact on the distribution of aquatic biodiversity from the understudied and ecologically complex Amazonia.
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7
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Saha A, Capowski E, Fernandez Zepeda MA, Nelson EC, Gamm DM, Sinha R. Cone photoreceptors in human stem cell-derived retinal organoids demonstrate intrinsic light responses that mimic those of primate fovea. Cell Stem Cell 2022; 29:460-471.e3. [PMID: 35104442 PMCID: PMC9093561 DOI: 10.1016/j.stem.2022.01.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 11/11/2021] [Accepted: 01/04/2022] [Indexed: 02/06/2023]
Abstract
High-definition vision in humans and nonhuman primates is initiated by cone photoreceptors located within a specialized region of the retina called the fovea. Foveal cone death is the ultimate cause of central blindness in numerous retinal dystrophies, including macular degenerative diseases. 3D retinal organoids (ROs) derived from human pluripotent stem cells (hPSCs) hold tremendous promise to model and treat such diseases. To achieve this goal, RO cones should elicit robust and intrinsic light-evoked electrical responses (i.e., phototransduction) akin to adult foveal cones, which has not yet been demonstrated. Here, we show strong, graded, repetitive, and wavelength-specific light-evoked responses from RO cones. The photoresponses and membrane physiology of a significant fraction of these lab-generated cones are comparable with those of intact ex vivo primate fovea. These results greatly increase confidence in ROs as potential sources of functional human cones for cell replacement therapies, drug testing, and in vitro models of retinal dystrophies.
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Affiliation(s)
- Aindrila Saha
- Department of Neuroscience, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA; Cellular and Molecular Biology Training Program, University of Wisconsin, Madison, WI, USA
| | | | | | - Emma C Nelson
- Waisman Center, University of Wisconsin, Madison, WI, USA
| | - David M Gamm
- McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA; Cellular and Molecular Biology Training Program, University of Wisconsin, Madison, WI, USA; Waisman Center, University of Wisconsin, Madison, WI, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
| | - Raunak Sinha
- Department of Neuroscience, University of Wisconsin, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, USA; Cellular and Molecular Biology Training Program, University of Wisconsin, Madison, WI, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA.
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8
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New In Vitro Cellular Model for Molecular Studies of Retinitis Pigmentosa. Int J Mol Sci 2021; 22:ijms22126440. [PMID: 34208617 PMCID: PMC8235468 DOI: 10.3390/ijms22126440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/04/2021] [Accepted: 06/13/2021] [Indexed: 02/05/2023] Open
Abstract
Retinitis pigmentosa (RP) is an inherited form of retinal degeneration characterized by primary rod photoreceptor cell death followed by cone loss. Mutations in several genes linked to the disease cause increased levels of cyclic guanosine monophosphate (cGMP) and calcium ion influxes. The purpose of this project was to develop a new in vitro photoreceptor degeneration model for molecular studies of RP. 661W cells were genetically modified to stably express the neural retina leucine zipper (NRL) transcription factor. One clone (661W-A11) was selected based on the expression of Nrl target genes. 661W-A11 showed a significant increase in expression of rod-specific genes but not of cone-specific genes, compared with 661W cells. Zaprinast was used to inhibit phosphodiesterase 6 (PDE6) activity to mimic photoreceptor degeneration in vitro. The activation of cell death pathways resulting from PDE6 inhibition was confirmed by detection of decreased viability and increased intracellular cGMP and calcium, as well as activation of protein kinase G (PKG) and calpains. In this new in vitro system, we validated the effects of previously published neuroprotective drugs. The 661W-A11 cells may serve as a new model for molecular studies of RP and for high-throughput drug screening.
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Kutsyr O, Sánchez-Sáez X, Martínez-Gil N, de Juan E, Lax P, Maneu V, Cuenca N. Gradual Increase in Environmental Light Intensity Induces Oxidative Stress and Inflammation and Accelerates Retinal Neurodegeneration. Invest Ophthalmol Vis Sci 2021; 61:1. [PMID: 32744596 PMCID: PMC7441298 DOI: 10.1167/iovs.61.10.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose Retinitis pigmentosa (RP) is a blinding neurodegenerative disease of the retina that can be affected by many factors. The present study aimed to analyze the effect of different environmental light intensities in rd10 mice retina. Methods C57BL/6J and rd10 mice were bred and housed under three different environmental light intensities: scotopic (5 lux), mesopic (50 lux), and photopic (300 lux). Visual function was studied using electroretinography and optomotor testing. The structural and morphological integrity of the retinas was evaluated by optical coherence tomography imaging and immunohistochemistry. Additionally, inflammatory processes and oxidative stress markers were analyzed by flow cytometry and western blotting. Results When the environmental light intensity was higher, retinal function decreased in rd10 mice and was accompanied by light-dependent photoreceptor loss, followed by morphological alterations, and synaptic connectivity loss. Moreover, light-dependent retinal degeneration was accompanied by an increased number of inflammatory cells, which became more activated and phagocytic, and by an exacerbated reactive gliosis. Furthermore, light-dependent increment in oxidative stress markers in rd10 mice retina pointed to a possible mechanism for light-induced photoreceptor degeneration. Conclusions An increase in rd10 mice housing light intensity accelerates retinal degeneration, activating cell death, oxidative stress pathways, and inflammatory cells. Lighting intensity is a key factor in the progression of retinal degeneration, and standardized lighting conditions are advisable for proper analysis and interpretation of experimental results from RP animal models, and specifically from rd10 mice. Also, it can be hypothesized that light protection could be an option to slow down retinal degeneration in some cases of RP.
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Khan FH, Dervan E, Bhattacharyya DD, McAuliffe JD, Miranda KM, Glynn SA. The Role of Nitric Oxide in Cancer: Master Regulator or NOt? Int J Mol Sci 2020; 21:ijms21249393. [PMID: 33321789 PMCID: PMC7763974 DOI: 10.3390/ijms21249393] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023] Open
Abstract
Nitric oxide (NO) is a key player in both the development and suppression of tumourigenesis depending on the source and concentration of NO. In this review, we discuss the mechanisms by which NO induces DNA damage, influences the DNA damage repair response, and subsequently modulates cell cycle arrest. In some circumstances, NO induces cell cycle arrest and apoptosis protecting against tumourigenesis. NO in other scenarios can cause a delay in cell cycle progression, allowing for aberrant DNA repair that promotes the accumulation of mutations and tumour heterogeneity. Within the tumour microenvironment, low to moderate levels of NO derived from tumour and endothelial cells can activate angiogenesis and epithelial-to-mesenchymal transition, promoting an aggressive phenotype. In contrast, high levels of NO derived from inducible nitric oxide synthase (iNOS) expressing M1 and Th1 polarised macrophages and lymphocytes may exert an anti-tumour effect protecting against cancer. It is important to note that the existing evidence on immunomodulation is mainly based on murine iNOS studies which produce higher fluxes of NO than human iNOS. Finally, we discuss different strategies to target NO related pathways therapeutically. Collectively, we present a picture of NO as a master regulator of cancer development and progression.
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Affiliation(s)
- Faizan H. Khan
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Eoin Dervan
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Dibyangana D. Bhattacharyya
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Jake D. McAuliffe
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Katrina M. Miranda
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA;
| | - Sharon A. Glynn
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
- Correspondence:
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11
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Barnes S, Grove JCR, McHugh CF, Hirano AA, Brecha NC. Horizontal Cell Feedback to Cone Photoreceptors in Mammalian Retina: Novel Insights From the GABA-pH Hybrid Model. Front Cell Neurosci 2020; 14:595064. [PMID: 33328894 PMCID: PMC7672006 DOI: 10.3389/fncel.2020.595064] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 09/24/2020] [Indexed: 01/20/2023] Open
Abstract
How neurons in the eye feed signals back to photoreceptors to optimize sensitivity to patterns of light appears to be mediated by one or more unconventional mechanisms. Via these mechanisms, horizontal cells control photoreceptor synaptic gain and enhance key aspects of temporal and spatial center-surround receptive field antagonism. After the transduction of light energy into an electrical signal in photoreceptors, the next key task in visual processing is the transmission of an optimized signal to the follower neurons in the retina. For this to happen, the release of the excitatory neurotransmitter glutamate from photoreceptors is carefully regulated via horizontal cell feedback, which acts as a thermostat to keep the synaptic transmission in an optimal range during changes to light patterns and intensities. Novel findings of a recently described model that casts a classical neurotransmitter system together with ion transport mechanisms to adjust the alkaline milieu outside the synapse are reviewed. This novel inter-neuronal messaging system carries feedback signals using two separate, but interwoven regulated systems. The complex interplay between these two signaling modalities, creating synaptic modulation-at-a-distance, has obscured it’s being defined. The foundations of our understanding of the feedback mechanism from horizontal cells to photoreceptors have been long established: Horizontal cells have broad receptive fields, suitable for providing surround inhibition, their membrane potential, a function of stimulus intensity and size, regulates inhibition of photoreceptor voltage-gated Ca2+ channels, and strong artificial pH buffering eliminates this action. This review compares and contrasts models of how these foundations are linked, focusing on a recent report in mammals that shows tonic horizontal cell release of GABA activating Cl− and HCO3− permeable GABA autoreceptors. The membrane potential of horizontal cells provides the driving force for GABAR-mediated HCO3− efflux, alkalinizing the cleft when horizontal cells are hyperpolarized by light or adding to their depolarization in darkness and contributing to cleft acidification via NHE-mediated H+ efflux. This model challenges interpretations of earlier studies that were considered to rule out a role for GABA in feedback to cones.
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Affiliation(s)
- Steven Barnes
- Doheny Eye Institute, Los Angeles, CA, United States.,Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - James C R Grove
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, United States
| | | | - Arlene A Hirano
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, United States
| | - Nicholas C Brecha
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, United States.,Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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12
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Bisbach CM, Hutto RA, Poria D, Cleghorn WM, Abbas F, Vinberg F, Kefalov VJ, Hurley JB, Brockerhoff SE. Mitochondrial Calcium Uniporter (MCU) deficiency reveals an alternate path for Ca 2+ uptake in photoreceptor mitochondria. Sci Rep 2020; 10:16041. [PMID: 32994451 PMCID: PMC7525533 DOI: 10.1038/s41598-020-72708-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/04/2020] [Indexed: 01/18/2023] Open
Abstract
Rods and cones use intracellular Ca2+ to regulate many functions, including phototransduction and neurotransmission. The Mitochondrial Calcium Uniporter (MCU) complex is thought to be the primary pathway for Ca2+ entry into mitochondria in eukaryotes. We investigate the hypothesis that mitochondrial Ca2+ uptake via MCU influences phototransduction and energy metabolism in photoreceptors using a mcu-/- zebrafish and a rod photoreceptor-specific Mcu-/- mouse. Using genetically encoded Ca2+ sensors to directly examine Ca2+ uptake in zebrafish cone mitochondria, we found that loss of MCU reduces but does not eliminate mitochondrial Ca2+ uptake. Loss of MCU does not lead to photoreceptor degeneration, mildly affects mitochondrial metabolism, and does not alter physiological responses to light, even in the absence of the Na+/Ca2+, K+ exchanger. Our results reveal that MCU is dispensable for vertebrate photoreceptor function, consistent with its low expression and the presence of an alternative pathway for Ca2+ uptake into photoreceptor mitochondria.
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Affiliation(s)
- Celia M Bisbach
- Biochemistry Department, University of Washington, Seattle, WA, USA
| | - Rachel A Hutto
- Biochemistry Department, University of Washington, Seattle, WA, USA
| | - Deepak Poria
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Fatima Abbas
- Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Frans Vinberg
- Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - James B Hurley
- Biochemistry Department, University of Washington, Seattle, WA, USA
- Ophthalmology Department, University of Washington, Seattle, WA, USA
| | - Susan E Brockerhoff
- Biochemistry Department, University of Washington, Seattle, WA, USA.
- Ophthalmology Department, University of Washington, Seattle, WA, USA.
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13
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Sensing through Non-Sensing Ocular Ion Channels. Int J Mol Sci 2020; 21:ijms21186925. [PMID: 32967234 PMCID: PMC7554890 DOI: 10.3390/ijms21186925] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/12/2022] Open
Abstract
Ion channels are membrane-spanning integral proteins expressed in multiple organs, including the eye. In the eye, ion channels are involved in various physiological processes, like signal transmission and visual processing. A wide range of mutations have been reported in the corresponding genes and their interacting subunit coding genes, which contribute significantly to an array of blindness, termed ocular channelopathies. These mutations result in either a loss- or gain-of channel functions affecting the structure, assembly, trafficking, and localization of channel proteins. A dominant-negative effect is caused in a few channels formed by the assembly of several subunits that exist as homo- or heteromeric proteins. Here, we review the role of different mutations in switching a “sensing” ion channel to “non-sensing,” leading to ocular channelopathies like Leber’s congenital amaurosis 16 (LCA16), cone dystrophy, congenital stationary night blindness (CSNB), achromatopsia, bestrophinopathies, retinitis pigmentosa, etc. We also discuss the various in vitro and in vivo disease models available to investigate the impact of mutations on channel properties, to dissect the disease mechanism, and understand the pathophysiology. Innovating the potential pharmacological and therapeutic approaches and their efficient delivery to the eye for reversing a “non-sensing” channel to “sensing” would be life-changing.
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14
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Abstract
Vision loss, among the most feared complications of diabetes, is primarily caused by diabetic retinopathy, a disease that manifests in well-recognized, characteristic microvascular lesions. The reasons for retinal susceptibility to damage in diabetes are unclear, especially considering that microvascular networks are found in all tissues. However, the unique metabolic demands of retinal neurons could account for their vulnerability in diabetes. Photoreceptors are the first neurons in the visual circuit and are also the most energy-demanding cells of the retina. Here, we review experimental and clinical evidence linking photoreceptors to the development of diabetic retinopathy. We then describe the influence of retinal illumination on photoreceptor metabolism, effects of light modulation on the severity of diabetic retinopathy, and recent clinical trials testing the treatment of diabetic retinopathy with interventions that impact photoreceptor metabolism. Finally, we introduce several possible mechanisms that could link photoreceptor responses to light and the development of retinal vascular disease in diabetes. Collectively, these concepts form the basis for a growing body of investigative efforts aimed at developing novel pharmacologic and nonpharmacologic tools that target photoreceptor physiology to treat a very common cause of blindness across the world.
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15
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Meschede IP, Ovenden NC, Seabra MC, Futter CE, Votruba M, Cheetham ME, Burgoyne T. Symmetric arrangement of mitochondria:plasma membrane contacts between adjacent photoreceptor cells regulated by Opa1. Proc Natl Acad Sci U S A 2020; 117:15684-15693. [PMID: 32571921 PMCID: PMC7355040 DOI: 10.1073/pnas.2000304117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Mitochondria are known to play an essential role in photoreceptor function and survival that enables normal vision. Within photoreceptors, mitochondria are elongated and extend most of the inner-segment length, where they supply energy for protein synthesis and the phototransduction machinery in the outer segment, as well as acting as a calcium store. Here, we examined the arrangement of the mitochondria within the inner segment in detail using three-dimensional (3D) electron microscopy techniques and show they are tethered to the plasma membrane in a highly specialized arrangement. Remarkably, mitochondria and their cristae openings align with those of neighboring inner segments. The pathway by which photoreceptors meet their high energy demands is not fully understood. We propose this to be a mechanism to share metabolites and assist in maintaining homeostasis across the photoreceptor cell layer. In the extracellular space between photoreceptors, Müller glial processes were identified. Due to the often close proximity to the inner-segment mitochondria, they may, too, play a role in the inner-segment mitochondrial arrangement as well as metabolite shuttling. OPA1 is an important factor in mitochondrial homeostasis, including cristae remodeling; therefore, we examined the photoreceptors of a heterozygous Opa1 knockout mouse model. The cristae structure in the Opa1+/- photoreceptors was not greatly affected, but the mitochondria were enlarged and had reduced alignment to neighboring inner-segment mitochondria. This indicates the importance of key regulators in maintaining this specialized photoreceptor mitochondrial arrangement.
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Affiliation(s)
- Ingrid P Meschede
- UCL Institute of Ophthalmology, University College London, EC1V 9EL London, United Kingdom
| | - Nicholas C Ovenden
- Department of Mathematics, University College London, WC1E 6BT London, United Kingdom
| | - Miguel C Seabra
- UCL Institute of Ophthalmology, University College London, EC1V 9EL London, United Kingdom
- Centro de Estudos de Doenças Crónicas, Universidade Nova de Lisboa, 1169-056 Lisbon, Portugal
| | - Clare E Futter
- UCL Institute of Ophthalmology, University College London, EC1V 9EL London, United Kingdom
| | - Marcela Votruba
- School of Optometry and Vision Sciences, Cardiff University, CF24 4HQ Cardiff, United Kingdom
- Cardiff Eye Unit, University Hospital Wales, CF14 4XW Cardiff, United Kingdom
| | - Michael E Cheetham
- UCL Institute of Ophthalmology, University College London, EC1V 9EL London, United Kingdom
| | - Thomas Burgoyne
- UCL Institute of Ophthalmology, University College London, EC1V 9EL London, United Kingdom;
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16
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Gagné AM, Moreau I, St-Amour I, Marquet P, Maziade M. Retinal function anomalies in young offspring at genetic risk of schizophrenia and mood disorder: The meaning for the illness pathophysiology. Schizophr Res 2020; 219:19-24. [PMID: 31320175 DOI: 10.1016/j.schres.2019.06.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 02/09/2023]
Abstract
BACKGROUND Visual defects are documented in psychiatric disorders such as schizophrenia, bipolar disorder and major depressive disorder. One of the most consistent alterations in patients is a change in cone and rod electroretinographic (ERG) responses. We previously showed a reduced rod b-wave amplitude in a small sample of young offspring born to an affected parent. A confirmation of the patients ERG anomalies in young offspring at high genetic risk would offer a new approach to the neurodevelopmental investigation of the illness. We thus investigated cone and rod responses in a larger sample of young healthy high-risk offspring. METHODS The ERG was recorded in 99 offspring of patients having DMS-IV schizophrenia, bipolar or major depressive disorder (mean age 16.03; SD 6.14) and in 223 healthy controls balanced for sex and age. The a- and b-wave latency and amplitude of cones and rods were recorded. RESULTS Cone b-wave latency was increased in offspring (ES = 0.31; P = 0.006) whereas rod b-wave amplitude was decreased (ES = -0.37; P = 0.001) and rod latency was increased (ES = 0.35; P = 0.002). CONCLUSIONS The ERG rod and cone abnormal response previously reported in adult patients having schizophrenia, bipolar disorder or major depressive disorder are detectable in genetically high-risk offspring as early as in childhood and adolescence. Moreover, a gradient of effect sizes among offspring and the three adult diagnoses was found in the cone response. This suggests that ERG waveform as a risk endophenotype might become part of the definition of a "childhood risk syndrome".
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Affiliation(s)
- Anne-Marie Gagné
- Centre de recherche CERVO, Centre Intégré Universitaire de Santé et des Services Sociaux de la Capitale-Nationale, Québec, Canada
| | - Isabel Moreau
- Centre de recherche CERVO, Centre Intégré Universitaire de Santé et des Services Sociaux de la Capitale-Nationale, Québec, Canada
| | - Isabelle St-Amour
- Centre de recherche CERVO, Centre Intégré Universitaire de Santé et des Services Sociaux de la Capitale-Nationale, Québec, Canada
| | - Pierre Marquet
- Centre de recherche CERVO, Centre Intégré Universitaire de Santé et des Services Sociaux de la Capitale-Nationale, Québec, Canada; Université Laval, Faculté de Médecine, Département de Psychiatrie et Neurosciences, Québec, Canada
| | - Michel Maziade
- Centre de recherche CERVO, Centre Intégré Universitaire de Santé et des Services Sociaux de la Capitale-Nationale, Québec, Canada; Université Laval, Faculté de Médecine, Département de Psychiatrie et Neurosciences, Québec, Canada.
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17
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Li X, Spelat R, Bartolini A, Cesselli D, Ius T, Skrap M, Caponnetto F, Manini I, Yang Y, Torre V. Mechanisms of malignancy in glioblastoma cells are linked to mitochondrial Ca 2 + uniporter upregulation and higher intracellular Ca 2+ levels. J Cell Sci 2020; 133:jcs.237503. [PMID: 32051286 DOI: 10.1242/jcs.237503] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 01/28/2020] [Indexed: 01/13/2023] Open
Abstract
Glioblastoma (GBM) is one of the most malignant brain tumours and, despite advances in treatment modalities, it remains largely incurable. Ca2+ regulation and dynamics play crucial roles in different aspects of cancer, but they have never been investigated in detail in GBM. Here, we report that spontaneous Ca2+ waves in GBM cells cause unusual intracellular Ca2+ ([Ca2+]i) elevations (>1 μM), often propagating through tumour microtubes (TMs) connecting adjacent cells. This unusual [Ca2+]i elevation is not associated with the induction of cell death and is concomitant with overexpression of mitochondrial Ca2+ uniporter (MCU). We show that MCU silencing decreases proliferation and alters [Ca2+]i dynamics in U87 GBM cells, while MCU overexpression increases [Ca2+]i elevation in human astrocytes (HAs). These results suggest that changes in the expression level of MCU, a protein involved in intracellular Ca2+ regulation, influences GBM cell proliferation, contributing to GBM malignancy.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Xiaoyun Li
- Neurobiology Sector, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Renza Spelat
- Neurobiology Sector, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Anna Bartolini
- Institute of Pathology, University Hospital of Udine, 33100 Udine, Italy
| | - Daniela Cesselli
- Institute of Pathology, University Hospital of Udine, 33100 Udine, Italy.,Department of Medicine, University of Udine, 33100 Udine, Italy
| | - Tamara Ius
- Neurosurgery Unit, Department of Neurosciences, University Hospital of Udine, 33100 Udine, Italy
| | - Miran Skrap
- Neurosurgery Unit, Department of Neurosciences, University Hospital of Udine, 33100 Udine, Italy
| | | | - Ivana Manini
- Department of Medicine, University of Udine, 33100 Udine, Italy
| | - Yili Yang
- Joint SISSA-ISM Laboratory, Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences, 215000 Suzhou, Jiangsu, China
| | - Vincent Torre
- Neurobiology Sector, International School for Advanced Studies (SISSA), 34136 Trieste, Italy .,Joint SISSA-ISM Laboratory, Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences, 215000 Suzhou, Jiangsu, China
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18
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Pasmanter N, Petersen-Jones SM. A review of electroretinography waveforms and models and their application in the dog. Vet Ophthalmol 2020; 23:418-435. [PMID: 32196872 DOI: 10.1111/vop.12759] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 02/04/2023]
Abstract
Electroretinography (ERG) is a commonly used technique to study retinal function in both clinical and research ophthalmology. ERG responses can be divided into component waveforms, analysis of which can provide insight into the health and function of different types and populations of retinal cells. In dogs, ERG has been used in the characterization of normal retinal function, as well as the diagnosis of retinal diseases and measuring effects of treatment. While many components of the recorded waveform are similar across species, dogs have several notable features that should be differentiated from the responses in humans and other animals. Additionally, modifications of standard protocols, such as changing flash frequency and stimulus color, and mathematical models of ERG waveforms have been used in studies of human retinal function but have been infrequently applied to visual electrophysiology in dogs. This review provides an overview of the origins and applications of ERG in addition to potential avenues for further characterization of responses in the dog.
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Affiliation(s)
- Nathaniel Pasmanter
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
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19
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Sundar JC, Munezero D, Bryan-Haring C, Saravanan T, Jacques A, Ramamurthy V. Rhodopsin signaling mediates light-induced photoreceptor cell death in rd10 mice through a transducin-independent mechanism. Hum Mol Genet 2020; 29:394-406. [PMID: 31925423 PMCID: PMC7015845 DOI: 10.1093/hmg/ddz299] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 11/22/2019] [Accepted: 12/02/2019] [Indexed: 01/08/2023] Open
Abstract
Retinitis pigmentosa (RP) is a debilitating blinding disease affecting over 1.5 million people worldwide, but the mechanisms underlying this disease are not well understood. One of the common models used to study RP is the retinal degeneration-10 (rd10) mouse, which has a mutation in Phosphodiesterase-6b (Pde6b) that causes a phenotype mimicking the human disease. In rd10 mice, photoreceptor cell death occurs with exposure to normal light conditions, but as demonstrated in this study, rearing these mice in dark preserves their retinal function. We found that inactivating rhodopsin signaling protected photoreceptors from degeneration suggesting that the pathway activated by this G-protein-coupled receptor is causing light-induced photoreceptor cell death in rd10 mice. However, inhibition of transducin signaling did not prevent the loss of photoreceptors in rd10 mice reared under normal light conditions implying that the degeneration caused by rhodopsin signaling is not mediated through its canonical G-protein transducin. Inexplicably, loss of transducin in rd10 mice also led to photoreceptor cell death in darkness. Furthermore, we found that the rd10 mutation in Pde6b led to a reduction in the assembled PDE6αβγ2 complex, which was corroborated by our data showing mislocalization of the γ subunit. Based on our findings and previous studies, we propose a model where light activates a non-canonical pathway mediated by rhodopsin but independent of transducin that sensitizes cyclic nucleotide gated channels to cGMP and causes photoreceptor cell death. These results generate exciting possibilities for treatment of RP patients without affecting their vision or the canonical phototransduction cascade.
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Affiliation(s)
- Jesse C Sundar
- Departments of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
| | - Daniella Munezero
- Departments of Ophthalmology and Visual Sciences, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
| | - Caitlyn Bryan-Haring
- Departments of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
| | - Thamaraiselvi Saravanan
- Departments of Ophthalmology and Visual Sciences, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
| | - Angelica Jacques
- Departments of Ophthalmology and Visual Sciences, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
| | - Visvanathan Ramamurthy
- Departments of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
- Departments of Ophthalmology and Visual Sciences, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
- Departments of Neuroscience, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26505, USA
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20
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Velez G, Sun YJ, Khan S, Yang J, Herrmann J, Chemudupati T, MacLaren RE, Gakhar L, Wakatsuki S, Bassuk AG, Mahajan VB. Structural Insights into the Unique Activation Mechanisms of a Non-classical Calpain and Its Disease-Causing Variants. Cell Rep 2020; 30:881-892.e5. [PMID: 31968260 PMCID: PMC7001764 DOI: 10.1016/j.celrep.2019.12.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/26/2019] [Accepted: 12/19/2019] [Indexed: 12/12/2022] Open
Abstract
Increased calpain activity is linked to neuroinflammation including a heritable retinal disease caused by hyper-activating mutations in the calcium-activated calpain-5 (CAPN5) protease. Although structures for classical calpains are known, the structure of CAPN5, a non-classical calpain, remains undetermined. Here we report the 2.8 Å crystal structure of the human CAPN5 protease core (CAPN5-PC). Compared to classical calpains, CAPN5-PC requires high calcium concentrations for maximal activity. Structure-based phylogenetic analysis and multiple sequence alignment reveal that CAPN5-PC contains three elongated flexible loops compared to its classical counterparts. The presence of a disease-causing mutation (c.799G>A, p.Gly267Ser) on the unique PC2L2 loop reveals a function in this region for regulating enzymatic activity. This mechanism could be transferred to distant calpains, using synthetic calpain hybrids, suggesting an evolutionary mechanism for fine-tuning calpain function by modifying flexible loops. Further, the open (inactive) conformation of CAPN5-PC provides structural insight into CAPN5-specific residues that can guide inhibitor design.
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Affiliation(s)
- Gabriel Velez
- Omics Laboratory, Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94304, USA; Medical Scientist Training Program, University of Iowa, Iowa City, IA 52242, USA
| | - Young Joo Sun
- Omics Laboratory, Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Saif Khan
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA 52242, USA; Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; Department of Biology and Biochemistry, University of Bath, Bath BA2 7AX, UK
| | - Jing Yang
- Omics Laboratory, Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Jonathan Herrmann
- Department of Structural Biology, Stanford University, Palo Alto, CA 94305, USA; Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Teja Chemudupati
- Omics Laboratory, Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Robert E MacLaren
- NIHR Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford EC1V 2PD, UK; Oxford Eye Hospital, University of Oxford NHS Trust, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Lokesh Gakhar
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA 52242, USA; Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Soichi Wakatsuki
- Department of Structural Biology, Stanford University, Palo Alto, CA 94305, USA; Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | | | - Vinit B Mahajan
- Omics Laboratory, Department of Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, CA 94304, USA; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA.
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21
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Ko GYP. Circadian regulation in the retina: From molecules to network. Eur J Neurosci 2020; 51:194-216. [PMID: 30270466 PMCID: PMC6441387 DOI: 10.1111/ejn.14185] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022]
Abstract
The mammalian retina is the most unique tissue among those that display robust circadian/diurnal oscillations. The retina is not only a light sensing tissue that relays light information to the brain, it has its own circadian "system" independent from any influence from other circadian oscillators. While all retinal cells and retinal pigment epithelium (RPE) possess circadian oscillators, these oscillators integrate by means of neural synapses, electrical coupling (gap junctions), and released neurochemicals (such as dopamine, melatonin, adenosine, and ATP), so the whole retina functions as an integrated circadian system. Dysregulation of retinal clocks not only causes retinal or ocular diseases, it also impacts the circadian rhythm of the whole body, as the light information transmitted from the retina entrains the brain clock that governs the body circadian rhythms. In this review, how circadian oscillations in various retinal cells are integrated, and how retinal diseases affect daily rhythms.
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Affiliation(s)
- Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas
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22
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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.
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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
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23
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Achberger K, Probst C, Haderspeck J, Bolz S, Rogal J, Chuchuy J, Nikolova M, Cora V, Antkowiak L, Haq W, Shen N, Schenke-Layland K, Ueffing M, Liebau S, Loskill P. Merging organoid and organ-on-a-chip technology to generate complex multi-layer tissue models in a human retina-on-a-chip platform. eLife 2019; 8:46188. [PMID: 31451149 PMCID: PMC6777939 DOI: 10.7554/elife.46188] [Citation(s) in RCA: 216] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/06/2019] [Indexed: 12/17/2022] Open
Abstract
The devastating effects and incurable nature of hereditary and sporadic retinal diseases such as Stargardt disease, age-related macular degeneration or retinitis pigmentosa urgently require the development of new therapeutic strategies. Additionally, a high prevalence of retinal toxicities is becoming more and more an issue of novel targeted therapeutic agents. Ophthalmologic drug development, to date, largely relies on animal models, which often do not provide results that are translatable to human patients. Hence, the establishment of sophisticated human tissue-based in vitro models is of upmost importance. The discovery of self-forming retinal organoids (ROs) derived from human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs) is a promising approach to model the complex stratified retinal tissue. Yet, ROs lack vascularization and cannot recapitulate the important physiological interactions of matured photoreceptors and the retinal pigment epithelium (RPE). In this study, we present the retina-on-a-chip (RoC), a novel microphysiological model of the human retina integrating more than seven different essential retinal cell types derived from hiPSCs. It provides vasculature-like perfusion and enables, for the first time, the recapitulation of the interaction of mature photoreceptor segments with RPE in vitro. We show that this interaction enhances the formation of outer segment-like structures and the establishment of in vivo-like physiological processes such as outer segment phagocytosis and calcium dynamics. In addition, we demonstrate the applicability of the RoC for drug testing, by reproducing the retinopathic side-effects of the anti-malaria drug chloroquine and the antibiotic gentamicin. The developed hiPSC-based RoC has the potential to promote drug development and provide new insights into the underlying pathology of retinal diseases.
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Affiliation(s)
- Kevin Achberger
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Christopher Probst
- Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany
| | - Jasmin Haderspeck
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Sylvia Bolz
- Centre for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Julia Rogal
- Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany.,Department of Women's Health, Research Institute for Women's Health, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Johanna Chuchuy
- Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany.,Department of Women's Health, Research Institute for Women's Health, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Marina Nikolova
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Virginia Cora
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Lena Antkowiak
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Wadood Haq
- Centre for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Nian Shen
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Katja Schenke-Layland
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls University Tübingen, Tübingen, Germany.,Natural and Medical Sciences Institute (NMI), Reutlingen, Germany.,Department of Medicine/Cardiology, Cardiovascular Research Laboratories, David Geffen School of Medicine, Los Angeles, United States
| | - Marius Ueffing
- Centre for Ophthalmology, Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Stefan Liebau
- Institute of Neuroanatomy & Developmental Biology (INDB), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Peter Loskill
- Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany.,Department of Women's Health, Research Institute for Women's Health, Eberhard Karls University Tübingen, Tübingen, Germany
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24
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Hutto RA, Bisbach CM, Abbas F, Brock DC, Cleghorn WM, Parker ED, Bauer BH, Ge W, Vinberg F, Hurley JB, Brockerhoff SE. Increasing Ca 2+ in photoreceptor mitochondria alters metabolites, accelerates photoresponse recovery, and reveals adaptations to mitochondrial stress. Cell Death Differ 2019; 27:1067-1085. [PMID: 31371786 PMCID: PMC7206026 DOI: 10.1038/s41418-019-0398-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/19/2019] [Accepted: 07/11/2019] [Indexed: 11/09/2022] Open
Abstract
Photoreceptors are specialized neurons that rely on Ca2+ to regulate phototransduction and neurotransmission. Photoreceptor dysfunction and degeneration occur when intracellular Ca2+ homeostasis is disrupted. Ca2+ homeostasis is maintained partly by mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniporter (MCU), which can influence cytosolic Ca2+ signals, stimulate energy production, and trigger apoptosis. Here we discovered that zebrafish cone photoreceptors express unusually low levels of MCU. We expected that this would be important to prevent mitochondrial Ca2+ overload and consequent cone degeneration. To test this hypothesis, we generated a cone-specific model of MCU overexpression. Surprisingly, we found that cones tolerate MCU overexpression, surviving elevated mitochondrial Ca2+ and disruptions to mitochondrial ultrastructure until late adulthood. We exploited the survival of MCU overexpressing cones to additionally demonstrate that mitochondrial Ca2+ uptake alters the distributions of citric acid cycle intermediates and accelerates recovery kinetics of the cone response to light. Cones adapt to mitochondrial Ca2+ stress by decreasing MICU3, an enhancer of MCU-mediated Ca2+ uptake, and selectively transporting damaged mitochondria away from the ellipsoid toward the synapse. Our findings demonstrate how mitochondrial Ca2+ can influence physiological and metabolic processes in cones and highlight the remarkable ability of cone photoreceptors to adapt to mitochondrial stress.
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Affiliation(s)
- Rachel A Hutto
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - Celia M Bisbach
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - Fatima Abbas
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, 84132, USA
| | - Daniel C Brock
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - Whitney M Cleghorn
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - Edward D Parker
- Opthalmology Department, University of Washington, Seattle, WA, 98109, USA
| | - Benjamin H Bauer
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - William Ge
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA
| | - Frans Vinberg
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, 84132, USA
| | - James B Hurley
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA.,Opthalmology Department, University of Washington, Seattle, WA, 98109, USA
| | - Susan E Brockerhoff
- Biochemistry Department, University of Washington, Seattle, WA, 98109, USA. .,Opthalmology Department, University of Washington, Seattle, WA, 98109, USA.
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25
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Balancing the Photoreceptor Proteome: Proteostasis Network Therapeutics for Inherited Retinal Disease. Genes (Basel) 2019; 10:genes10080557. [PMID: 31344897 PMCID: PMC6722924 DOI: 10.3390/genes10080557] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 07/09/2019] [Accepted: 07/16/2019] [Indexed: 12/17/2022] Open
Abstract
The light sensing outer segments of photoreceptors (PRs) are renewed every ten days due to their high photoactivity, especially of the cones during daytime vision. This demands a tremendous amount of energy, as well as a high turnover of their main biosynthetic compounds, membranes, and proteins. Therefore, a refined proteostasis network (PN), regulating the protein balance, is crucial for PR viability. In many inherited retinal diseases (IRDs) this balance is disrupted leading to protein accumulation in the inner segment and eventually the death of PRs. Various studies have been focusing on therapeutically targeting the different branches of the PR PN to restore the protein balance and ultimately to treat inherited blindness. This review first describes the different branches of the PN in detail. Subsequently, insights are provided on how therapeutic compounds directed against the different PN branches might slow down or even arrest the appalling, progressive blinding conditions. These insights are supported by findings of PN modulators in other research disciplines.
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26
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Ma H, Yang F, Butler MR, Rapp J, Le YZ, Ding XQ. Ryanodine Receptor 2 Contributes to Impaired Protein Localization in Cyclic Nucleotide-Gated Channel Deficiency. eNeuro 2019; 6:ENEURO.0119-19.2019. [PMID: 31182474 PMCID: PMC6597858 DOI: 10.1523/eneuro.0119-19.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/20/2019] [Accepted: 05/21/2019] [Indexed: 01/28/2023] Open
Abstract
The photoreceptor cyclic nucleotide-gated (CNG) channel plays a pivotal role in phototransduction and cellular calcium homeostasis. Mutations in the cone photoreceptor CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. CNG channel deficiency leads to endoplasmic reticulum (ER) stress-associated cone apoptosis, protein mislocalization, and ER calcium dysregulation. This work investigated the potential mechanisms of protein mislocalization associated with ER calcium dysregulation using Cnga3-/- mice lacking ER Ca2+ channel ryanodine receptor 2 (RyR2) specifically in cones. Deletion of Ryr2 improved outer segment (OS) localization of the cone proteins M-opsin, S-opsin, and cone phosphodiesterase subunit α' (PDE6C) and decreased inner segment localization. One-month-old Cnga3-/- mice showed ∼30% of M-opsin, 55% of S-opsin, and 50% of PDE6C localized to the OS. Cnga3-/- mice with Ryr2 deletion at the same age showed almost 60% of M-opsin, 70% of S-opsin, and 70% of PDE6C localized to the OS. Deletion of Ryr2 nearly completely reversed elevations of the ER stress markers phospho-IRE1α and phospho-eIF2α and suppressed cone apoptosis. Consistent with the improved cone protein localization and reduced ER stress/cone apoptosis, cone survival was improved by deletion of Ryr2 The number of cones was increased by ∼28% in 2- to 4-month-old Cnga3-/- mice with Ryr2 deletion compared with age-matched Cnga3-/- mice. This work demonstrates a role of RyR2/ER calcium dysregulation in protein mislocalization, ER stress, and cone death. The findings provide novel insights into the mechanisms of photoreceptor degeneration and support strategies targeting ER calcium regulation to manage retinal degeneration.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Jacob Rapp
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Yun-Zheng Le
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Department of Medicine, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Department of Ophthalmology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
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27
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Signaling by hydrogen sulfide (H2S) and polysulfides (H2Sn) in the central nervous system. Neurochem Int 2019; 126:118-125. [DOI: 10.1016/j.neuint.2019.01.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 01/13/2023]
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28
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Saxena S, Nim DK, Stefanickova J, Ziak P, Stefanicka P, Kruzliak P. Retinal photoreceptor apoptosis is associated with impaired serum ionized calcium homeostasis in diabetic retinopathy: An in-vivo analysis. J Diabetes Complications 2019; 33:208-211. [PMID: 30595402 DOI: 10.1016/j.jdiacomp.2018.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 02/01/2023]
Abstract
PURPOSE The aim of this work was to study the association of serum ionized calcium with retinal photoreceptor apoptosis on spectral domain optical coherence tomography (SD-OCT) in diabetic retinopathy (DR). METHODS Sixty consecutive cases with Type 2 diabetes mellitus were categorized into three groups: no diabetic retinopathy; non-proliferative DR; proliferative DR. The eye with more severe form of the disease was considered. Twenty healthy controls were also included. Best corrected visual acuity (BCVA) was measured on logMAR scale. Retinal photoreceptor apoptosis was defined as disruption of retinal photoreceptor ellipsoid zone (EZ). Ellipsoid zone disruption was assessed using SD-OCT. Serum levels of total and ionized calcium were measured using standard protocol. RESULTS EZ disruption was found to be positively associated with serum total calcium and ionized calcium. Also, EZ disruption was found to be positively associated with logMAR BCVA. CONCLUSION Increased serum ionized calcium induces retinal photoreceptor apoptosis resulting in increased EZ disruption in DR.
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Affiliation(s)
- Sandeep Saxena
- Department of Ophthalmology, King George's Medical University, Lucknow, India.
| | - Dwividendra K Nim
- Department of Pharmacology, Employee's State Insurance Corporation Medical College and Hospital, Haryana, India
| | - Jana Stefanickova
- Department of Ophthalmology, Faculty of Medicine, Comenius University and University Hospital, Bratislava, Slovakia
| | - Peter Ziak
- Clinic of Ophthalmology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Patrik Stefanicka
- Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, Comenius University and University Hospital, Bratislava, Slovakia
| | - Peter Kruzliak
- Department of Internal Medicine, Brothers of Mercy Hospital, Brno, Czech Republic; 2nd Department of Surgery, Faculty of Medicine, St. Anne's University Hospital, Brno, Czech Republic.
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29
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Hyperglycemia potentiates the effect of ionic calcium in photoreceptor ellipsoid zone disruption in diabetic retinopathy. Int Ophthalmol 2019; 39:2237-2243. [PMID: 30628026 DOI: 10.1007/s10792-018-01063-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Accepted: 12/21/2018] [Indexed: 01/26/2023]
Abstract
PURPOSE To study the association of serum ionic calcium and glycated hemoglobin (HbA1c) with retinal photoreceptor ellipsoid zone (EZ) disruption in diabetic retinopathy (DR). METHODS This is a tertiary care center-based observational cross-sectional study. Sixty-three consecutive cases, divided into 21 cases each with no diabetic retinopathy, non-proliferative diabetic retinopathy and proliferative diabetic retinopathy were included. Twenty-one healthy controls were also included. Ellipsoid zone disruption was assessed using spectral-domain optical coherence tomography. Serum ionic calcium and HbA1c were measured using standard protocol. Patient data from cases were divided into two groups according to their HbA1c levels: group 1 (HbA1c < 7, n = 26) and group 2 (HbA1c > 7, n = 37). Data were analyzed statistically. RESULTS Mean ionic calcium levels in group 1 and group 2 were 1.131 ± 0.073 mmol/dL and 1.170 ± 0.070 mmol/dL, respectively. In group 1, 11 out of 26 had EZ disruption (42.3%). Similarly, in group 2, 29 out of 37 had EZ disruption (78.4%). On logistic regression analysis, as compared to group 1, ellipsoid zone disruption was found to be positively associated with serum ionic calcium (p = 0.01) in group 2 cases. CONCLUSION Increased levels of serum ionic calcium are associated with increased EZ disruption in patients with HbA1c > 7 in DR.
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30
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Mir JM, Maurya RC. Physiological and pathophysiological implications of hydrogen sulfide: a persuasion to change the fate of the dangerous molecule. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/22243682.2018.1493951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jan Mohammad Mir
- Coordination, Bioinorganic and Computational Chemistry Laboratory, Department of P. G. Studies and Research in Chemistry & Pharmacy, R. D. University, Jabalpur, India
| | - Ram Charitra Maurya
- Coordination, Bioinorganic and Computational Chemistry Laboratory, Department of P. G. Studies and Research in Chemistry & Pharmacy, R. D. University, Jabalpur, India
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31
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Medrano MP, Pisera Fuster A, Sanchis PA, Paez N, Bernabeu RO, Faillace MP. Characterization of proliferative, glial and angiogenic responses after a CoCl
2
‐induced injury of photoreceptor cells in the adult zebrafish retina. Eur J Neurosci 2018; 48:3019-3042. [DOI: 10.1111/ejn.14113] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 07/13/2018] [Accepted: 08/03/2018] [Indexed: 01/05/2023]
Affiliation(s)
- Matias Pedro Medrano
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
| | - Antonella Pisera Fuster
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
| | - Pablo Antonio Sanchis
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
| | - Natalia Paez
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
| | - Ramon Oscar Bernabeu
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
- Departamento de FisiologíaFacultad de MedicinaUniversidad de Buenos Aires (UBA) Buenos Aires Argentina
| | - Maria Paula Faillace
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO‐Houssay) UBA y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Buenos Aires Argentina
- Departamento de FisiologíaFacultad de MedicinaUniversidad de Buenos Aires (UBA) Buenos Aires Argentina
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32
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Waldner DM, Bech-Hansen NT, Stell WK. Channeling Vision: Ca V1.4-A Critical Link in Retinal Signal Transmission. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7272630. [PMID: 29854783 PMCID: PMC5966690 DOI: 10.1155/2018/7272630] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/15/2018] [Indexed: 01/09/2023]
Abstract
Voltage-gated calcium channels (VGCC) are key to many biological functions. Entry of Ca2+ into cells is essential for initiating or modulating important processes such as secretion, cell motility, and gene transcription. In the retina and other neural tissues, one of the major roles of Ca2+-entry is to stimulate or regulate exocytosis of synaptic vesicles, without which synaptic transmission is impaired. This review will address the special properties of one L-type VGCC, CaV1.4, with particular emphasis on its role in transmission of visual signals from rod and cone photoreceptors (hereafter called "photoreceptors," to the exclusion of intrinsically photoreceptive retinal ganglion cells) to the second-order retinal neurons, and the pathological effects of mutations in the CACNA1F gene which codes for the pore-forming α1F subunit of CaV1.4.
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Affiliation(s)
- D. M. Waldner
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - N. T. Bech-Hansen
- Department of Medical Genetics and Department of Surgery, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - W. K. Stell
- Department of Cell Biology and Anatomy and Department of Surgery, Hotchkiss Brain Institute, and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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33
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Vladimirov VI, Zernii EY, Baksheeva VE, Wimberg H, Kazakov AS, Tikhomirova NK, Nemashkalova EL, Mitkevich VA, Zamyatnin AA, Lipkin VM, Philippov PP, Permyakov SE, Senin II, Koch KW, Zinchenko DV. Photoreceptor calcium sensor proteins in detergent-resistant membrane rafts are regulated via binding to caveolin-1. Cell Calcium 2018; 73:55-69. [PMID: 29684785 DOI: 10.1016/j.ceca.2018.04.003] [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: 11/27/2017] [Revised: 04/07/2018] [Accepted: 04/10/2018] [Indexed: 01/25/2023]
Abstract
Rod cell membranes contain cholesterol-rich detergent-resistant membrane (DRM) rafts, which accumulate visual cascade proteins as well as proteins involved in regulation of phototransduction such as rhodopsin kinase and guanylate cyclases. Caveolin-1 is the major integral component of DRMs, possessing scaffolding and regulatory activities towards various signaling proteins. In this study, photoreceptor Ca2+-binding proteins recoverin, NCS1, GCAP1, and GCAP2, belonging to neuronal calcium sensor (NCS) family, were recognized as novel caveolin-1 interacting partners. All four NCS proteins co-fractionate with caveolin-1 in DRMs, isolated from illuminated bovine rod outer segments. According to pull-down assay, surface plasmon resonance spectroscopy and isothermal titration calorimetry data, they are capable of high-affinity binding to either N-terminal fragment of caveolin-1 (1-101), or its short scaffolding domain (81-101) via a novel structural site. In recoverin this site is localized in C-terminal domain in proximity to the third EF-hand motif and composed of aromatic amino acids conserved among NCS proteins. Remarkably, the binding of NCS proteins to caveolin-1 occurs only in the absence of calcium, which is in agreement with higher accessibility of the caveolin-1 binding site in their Ca2+-free forms. Consistently, the presence of caveolin-1 produces no effect on regulatory activity of Ca2+-saturated recoverin or NCS1 towards rhodopsin kinase, but upregulates GCAP2, which potentiates guanylate cyclase activity being in Ca2+-free conformation. In addition, the interaction with caveolin-1 decreases cooperativity and augments affinity of Ca2 + binding to recoverin apparently by facilitating exposure of its myristoyl group. We suggest that at low calcium NCS proteins are compartmentalized in photoreceptor rafts via binding to caveolin-1, which may enhance their activity or ensure their faster responses on Ca2+-signals thereby maintaining efficient phototransduction recovery and light adaptation.
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Affiliation(s)
- Vasiliy I Vladimirov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Evgeni Yu Zernii
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Viktoriia E Baksheeva
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Hanna Wimberg
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Oldenburg, 26111 Germany
| | - Alexey S Kazakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Natalya K Tikhomirova
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Ekaterina L Nemashkalova
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Vladimir A Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Andrey A Zamyatnin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Valery M Lipkin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Pavel P Philippov
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Sergei E Permyakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Ivan I Senin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Karl-W Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Oldenburg, 26111 Germany
| | - Dmitry V Zinchenko
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
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Butler MR, Ma H, Yang F, Belcher J, Le YZ, Mikoshiba K, Biel M, Michalakis S, Iuso A, Križaj D, Ding XQ. Endoplasmic reticulum (ER) Ca 2+-channel activity contributes to ER stress and cone death in cyclic nucleotide-gated channel deficiency. J Biol Chem 2017; 292:11189-11205. [PMID: 28495882 DOI: 10.1074/jbc.m117.782326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/01/2017] [Indexed: 02/05/2023] Open
Abstract
Endoplasmic reticulum (ER) stress and mislocalization of improperly folded proteins have been shown to contribute to photoreceptor death in models of inherited retinal degenerative diseases. In particular, mice with cone cyclic nucleotide-gated (CNG) channel deficiency, a model for achromatopsia, display both early-onset ER stress and opsin mistrafficking. By 2 weeks of age, these mice show elevated signaling from all three arms of the ER-stress pathway, and by 1 month, cone opsin is improperly distributed away from its normal outer segment location to other retinal layers. This work investigated the role of Ca2+-release channels in ER stress, protein mislocalization, and cone death in a mouse model of CNG-channel deficiency. We examined whether preservation of luminal Ca2+ stores through pharmacological and genetic suppression of ER Ca2+ efflux protects cones by attenuating ER stress. We demonstrated that the inhibition of ER Ca2+-efflux channels reduced all three arms of ER-stress signaling while improving opsin trafficking to cone outer segments and decreasing cone death by 20-35%. Cone-specific gene deletion of the inositol-1,4,5-trisphosphate receptor type I (IP3R1) also significantly increased cone density in the CNG-channel-deficient mice, suggesting that IP3R1 signaling contributes to Ca2+ homeostasis and cone survival. Consistent with the important contribution of organellar Ca2+ signaling in this achromatopsia mouse model, significant differences in dynamic intraorganellar Ca2+ levels were detected in CNG-channel-deficient cones. These results thus identify a novel molecular link between Ca2+ homeostasis and cone degeneration, thereby revealing novel therapeutic targets to preserve cones in inherited retinal degenerative diseases.
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Affiliation(s)
| | | | - Fan Yang
- From the Departments of Cell Biology
| | | | - Yun-Zheng Le
- From the Departments of Cell Biology.,Internal Medicine, and.,Ophthalmology and.,the Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Katsuhiko Mikoshiba
- the Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Hirosawa Wako-shi, Saitama 351-0198, Japan
| | - Martin Biel
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Stylianos Michalakis
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Anthony Iuso
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
| | - David Križaj
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
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35
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Do photoreceptor cells cause the development of retinal vascular disease? Vision Res 2017; 139:65-71. [PMID: 28438678 DOI: 10.1016/j.visres.2017.03.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/29/2017] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
Abstract
The retinal vasculature is affected in a number of clinically important retinopathies, including diabetic retinopathy. There has been a considerable amount of research into the pathogenesis of retinal microvascular diseases, but the potential contribution of the most abundant cell population in the retina, photoreceptor cells, has been largely overlooked. This review summarizes ongoing research suggesting that photoreceptor cells play a critical role in the development of retinal vascular disease in diabetic retinopathy and other retinopathies.
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Mitochondria Maintain Distinct Ca 2+ Pools in Cone Photoreceptors. J Neurosci 2017; 37:2061-2072. [PMID: 28115482 DOI: 10.1523/jneurosci.2689-16.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 01/01/2023] Open
Abstract
Ca2+ ions have distinct roles in the outer segment, cell body, and synaptic terminal of photoreceptors. We tested the hypothesis that distinct Ca2+ domains are maintained by Ca2+ uptake into mitochondria. Serial block face scanning electron microscopy of zebrafish cones revealed that nearly 100 mitochondria cluster at the apical side of the inner segment, directly below the outer segment. The endoplasmic reticulum surrounds the basal and lateral surfaces of this cluster, but does not reach the apical surface or penetrate into the cluster. Using genetically encoded Ca2+ sensors, we found that mitochondria take up Ca2+ when it accumulates either in the cone cell body or outer segment. Blocking mitochondrial Ca2+ uniporter activity compromises the ability of mitochondria to maintain distinct Ca2+ domains. Together, our findings indicate that mitochondria can modulate subcellular functional specialization in photoreceptors.SIGNIFICANCE STATEMENT Ca2+ homeostasis is essential for the survival and function of retinal photoreceptors. Separate pools of Ca2+ regulate phototransduction in the outer segment, metabolism in the cell body, and neurotransmitter release at the synaptic terminal. We investigated the role of mitochondria in compartmentalization of Ca2+ We found that mitochondria form a dense cluster that acts as a diffusion barrier between the outer segment and cell body. The cluster is surprisingly only partially surrounded by the endoplasmic reticulum, a key mediator of mitochondrial Ca2+ uptake. Blocking the uptake of Ca2+ by mitochondria causes redistribution of Ca2+ throughout the cell. Our results show that mitochondrial Ca2+ uptake in photoreceptors is complex and plays an essential role in normal function.
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Brockerhoff SE. Genome Editing to Study Ca 2+ Homeostasis in Zebrafish Cone Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1016:91-100. [PMID: 29130155 DOI: 10.1007/978-3-319-63904-8_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Photoreceptors are specialized sensory neurons with unique biological features. Phototransduction is well understood due in part to the exclusive expression and function of the molecular components of this cascade. Many other processes are less well understood, but also extremely important for understanding photoreceptor function and for treating disease. One example is the role of Ca2+ in the cell body and overall compartmentalization and regulation of Ca2+ within the cell. The recent development of CRISPR/Cas9 genome editing techniques has made it possible to rapidly and cheaply alter specific genes. This will help to define the biological function of elusive processes that have been more challenging to study. CRISPR/Cas9 has been optimized in many systems including zebrafish, which already has some distinct advantages for studying photoreceptor biology and function. These new genome editing technologies and the continued use of the zebrafish model system will help advance our understanding of important understudied aspects of photoreceptor biology.
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Affiliation(s)
- Susan E Brockerhoff
- Departments of Biochemistry and Ophthalmology, University of Washington, UW Medicine, 750 Republican St, Box 358058, Seattle, WA, 98109, USA.
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38
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Shinde V, Kotla P, Strang C, Gorbatyuk M. Unfolded protein response-induced dysregulation of calcium homeostasis promotes retinal degeneration in rat models of autosomal dominant retinitis pigmentosa. Cell Death Dis 2016; 7:e2085. [PMID: 26844699 PMCID: PMC4670931 DOI: 10.1038/cddis.2015.325] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 09/15/2015] [Accepted: 09/30/2015] [Indexed: 12/12/2022]
Abstract
The molecular mechanism of autosomal dominant retinitis pigmentosa (ADRP) in rats is closely associated with a persistently activated unfolded protein response (UPR). If unchecked, the UPR might trigger apoptosis, leading to photoreceptor death. One of the UPR-activated cellular signaling culminating in apoptotic photoreceptor cell death is linked to an increase in intracellular Ca(2+). Therefore, we validated whether ADRP retinas experience a cytosolic Ca(2+) overload, and whether sustained UPR in the wild-type retina could promote retinal degeneration through Ca(2+)-mediated calpain activation. We performed an ex vivo experiment to measure intracellular Ca(2+) in ADRP retinas as well as to detect the expression levels of proteins that act as Ca(2+) sensors. In separate experiments with the subretinal injection of tunicamycin (UPR inducer) and a mixture of calcium ionophore (A231278) and thapsigargin (SERCA2b inhibitor) we assessed the consequences of a sustained UPR activation and increased intracellular Ca(2+) in the wild-type retina, respectively, by performing scotopic ERG, histological, and western blot analyses. Results of the study revealed that induced UPR in the retina activates calpain-mediated signaling, and increased intracellular Ca(2+) is capable of promoting retinal degeneration. A significant decline in ERG amplitudes at 6 weeks post treatment was associated with photoreceptor cell loss that occurred through calpain-activated CDK5-pJNK-Csp3/7 pathway. Similar calpain activation was found in ADRP rat retinas. A twofold increase in intracellular Ca(2+) and up- and downregulations of ER membrane-associated Ca(2+)-regulated IP3R channels and SERCA2b transporters were detected. Therefore, sustained UPR activation in the ADRP rat retinas could promote retinal degeneration through increased intracellular Ca(2+) and calpain-mediated apoptosis.
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Affiliation(s)
- V Shinde
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - P Kotla
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - C Strang
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - M Gorbatyuk
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
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Du J, Rountree A, Cleghorn WM, Contreras L, Lindsay KJ, Sadilek M, Gu H, Djukovic D, Raftery D, Satrústegui J, Kanow M, Chan L, Tsang SH, Sweet IR, Hurley JB. Phototransduction Influences Metabolic Flux and Nucleotide Metabolism in Mouse Retina. J Biol Chem 2015; 291:4698-710. [PMID: 26677218 DOI: 10.1074/jbc.m115.698985] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Indexed: 01/20/2023] Open
Abstract
Production of energy in a cell must keep pace with demand. Photoreceptors use ATP to maintain ion gradients in darkness, whereas in light they use it to support phototransduction. Matching production with consumption can be accomplished by coupling production directly to consumption. Alternatively, production can be set by a signal that anticipates demand. In this report we investigate the hypothesis that signaling through phototransduction controls production of energy in mouse retinas. We found that respiration in mouse retinas is not coupled tightly to ATP consumption. By analyzing metabolic flux in mouse retinas, we also found that phototransduction slows metabolic flux through glycolysis and through intermediates of the citric acid cycle. We also evaluated the relative contributions of regulation of the activities of α-ketoglutarate dehydrogenase and the aspartate-glutamate carrier 1. In addition, a comprehensive analysis of the retinal metabolome showed that phototransduction also influences steady-state concentrations of 5'-GMP, ribose-5-phosphate, ketone bodies, and purines.
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Affiliation(s)
- Jianhai Du
- From the Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | | | | | - Laura Contreras
- Department of Molecular Biology, Centre for Molecular Biology Severo Ochoa, Universidad Autonoma de Madrid-Consejo Superior de Investigaciones Científicas, CIBER of Rare Diseases (CIBERER), and Health Research Institute Jimenez Diaz Foundation, Autonomous University of Madrid, 28049 Madrid, Spain
| | | | | | - Haiwei Gu
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Danijel Djukovic
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Dan Raftery
- Northwest Metabolomics Research Center, Department of Anesthesiology and Pain Medicine
| | - Jorgina Satrústegui
- Department of Molecular Biology, Centre for Molecular Biology Severo Ochoa, Universidad Autonoma de Madrid-Consejo Superior de Investigaciones Científicas, CIBER of Rare Diseases (CIBERER), and Health Research Institute Jimenez Diaz Foundation, Autonomous University of Madrid, 28049 Madrid, Spain
| | | | - Lawrence Chan
- Bernard and Shirlee Brown Glaucoma Laboratory and Barbara and Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, New York, and
| | - Stephen H Tsang
- Bernard and Shirlee Brown Glaucoma Laboratory and Barbara and Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, New York, and Department of Pathology and Cell Biology and Institute of Human Nutrition, Columbia University, New York, New York 10032
| | | | - James B Hurley
- From the Department of Biochemistry, Department of Ophthalmology, University of Washington, Seattle, Washington 98109,
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40
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Chang RCA, Shi L, Huang CCY, Kim AJ, Ko ML, Zhou B, Ko GYP. High-Fat Diet-Induced Retinal Dysfunction. Invest Ophthalmol Vis Sci 2015; 56:2367-80. [PMID: 25788653 DOI: 10.1167/iovs.14-16143] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE The purpose of this study was to investigate the impact of obesity-induced prediabetes/early diabetes on the retina to provide new evidence on the pathogenesis of type 2 diabetes-associated diabetic retinopathy (DR). METHODS A high-fat diet (HFD)-induced obesity mouse model (male C57BL/6J) was used in this study. At the end of the 12-week HFD feeding regimen, mice were evaluated for glucose and insulin tolerance, and retinal light responses were recorded by electroretinogram (ERG). Western immunoblot and immunohistochemical staining were used to determine changes in elements regulating calcium homeostasis between HFD and control retinas, as well as unstained human retinal sections from DR patients and age-appropriate controls. RESULTS Compared to the control, the scotopic and photopic ERGs from HFD mice were decreased. There were significant decreases in molecules related to cell signaling, calcium homeostasis, and glucose metabolism from HFD retinas, including phosphorylated protein kinase B (pAKT), glucose transporter 4, L-type voltage-gated calcium channel (L-VGCC), and plasma membrane calcium ATPase (PMCA). Similar changes for pAKT, PMCA, and L-VGCC were also observed in human retinal sections from DR patients. CONCLUSIONS Obesity-induced hyperglycemic and prediabetic/early diabetic conditions caused detrimental impacts on retinal light sensitivities and health. The decrease of the ERG components in early diabetes reflects the decreased neuronal activity of retinal light responses, which may be caused by a decrease in neuronal calcium signaling. Since PI3K-AKT is important in regulating calcium homeostasis and neural survival, maintaining proper PI3K-AKT signaling in early diabetes or at the prediabetic stage might be a new strategy for DR prevention.
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Affiliation(s)
- Richard Cheng-An Chang
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Liheng Shi
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Cathy Chia-Yu Huang
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Andy Jeesu Kim
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Michael L Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Beiyan Zhou
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States
| | - Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States 3Texas A&M Institute of Neuroscience, Texas A&M University, College Station, Texas, Unite
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Ou J, Vijayasarathy C, Ziccardi L, Chen S, Zeng Y, Marangoni D, Pope JG, Bush RA, Wu Z, Li W, Sieving PA. Synaptic pathology and therapeutic repair in adult retinoschisis mouse by AAV-RS1 transfer. J Clin Invest 2015; 125:2891-903. [PMID: 26098217 DOI: 10.1172/jci81380] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/30/2015] [Indexed: 01/24/2023] Open
Abstract
Strategies aimed at invoking synaptic plasticity have therapeutic potential for several neurological conditions. The human retinal synaptic disease X-linked retinoschisis (XLRS) is characterized by impaired visual signal transmission through the retina and progressive visual acuity loss, and mice lacking retinoschisin (RS1) recapitulate human disease. Here, we demonstrate that restoration of RS1 via retina-specific delivery of adeno-associated virus type 8-RS1 (AAV8-RS1) vector rescues molecular pathology at the photoreceptor-depolarizing bipolar cell (photoreceptor-DBC) synapse and restores function in adult Rs1-KO animals. Initial development of the photoreceptor-DBC synapse was normal in the Rs1-KO retina; however, the metabotropic glutamate receptor 6/transient receptor potential melastatin subfamily M member 1-signaling (mGluR6/TRPM1-signaling) cascade was not properly maintained. Specifically, the TRPM1 channel and G proteins Gαo, Gβ5, and RGS11 were progressively lost from postsynaptic DBC dendritic tips, whereas the mGluR6 receptor and RGS7 maintained proper synaptic position. This postsynaptic disruption differed from other murine night-blindness models with an electronegative electroretinogram response, which is also characteristic of murine and human XLRS disease. Upon AAV8-RS1 gene transfer to the retina of adult XLRS mice, TRPM1 and the signaling molecules returned to their proper dendritic tip location, and the DBC resting membrane potential was restored. These findings provide insight into the molecular plasticity of a critical synapse in the visual system and demonstrate potential therapeutic avenues for some diseases involving synaptic pathology.
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The phototransduction machinery in the rod outer segment has a strong efficacy gradient. Proc Natl Acad Sci U S A 2015; 112:E2715-24. [PMID: 25941368 DOI: 10.1073/pnas.1423162112] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Rod photoreceptors consist of an outer segment (OS) and an inner segment. Inside the OS a biochemical machinery transforms the rhodopsin photoisomerization into electrical signal. This machinery has been treated as and is thought to be homogenous with marginal inhomogeneities. To verify this assumption, we developed a methodology based on special tapered optical fibers (TOFs) to deliver highly localized light stimulations. By using these TOFs, specific regions of the rod OS could be stimulated with spots of light highly confined in space. As the TOF is moved from the OS base toward its tip, the amplitude of saturating and single photon responses decreases, demonstrating that the efficacy of the transduction machinery is not uniform and is 5-10 times higher at the base than at the tip. This gradient of efficacy of the transduction machinery is attributed to a progressive depletion of the phosphodiesterase along the rod OS. Moreover we demonstrate that, using restricted spots of light, the duration of the photoresponse along the OS does not increase linearly with the light intensity as with diffuse light.
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Abstract
SIGNIFICANCE Hydrogen sulfide (H2S) has been recognized as a signaling molecule as well as a cytoprotectant. It modulates neurotransmission, regulates vascular tone, and protects various tissues and organs, including neurons, the heart, and kidneys, from oxidative stress and ischemia-reperfusion injury. H2S is produced from l-cysteine by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST) along with cysteine aminotransferase. RECENT ADVANCES In addition to these enzymes, we recently identified a novel pathway to produce H2S from d-cysteine, which involves d-amino acid oxidase (DAO) along with 3MST. These enzymes are localized in the cytoplasm, mitochondria, and peroxisomes. However, some enzymes translocate to organelles under specific conditions. Moreover, H2S-derived potential signaling molecules such as polysulfides and HSNO have been identified. CRITICAL ISSUES The physiological stimulations, which trigger the production of H2S and its derivatives and maintain their local levels, remain unclear. FUTURE DIRECTIONS Understanding the regulation of the H2S production and H2S-derived signaling molecules and the specific stimuli that induce their release will provide new insights into the biology of H2S and therapeutic development in diseases involving these substances.
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Affiliation(s)
- Hideo Kimura
- National Institute of Neuroscience , National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
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Abstract
Although photoreceptors account for most of the mass and metabolic activity of the retina, their role in the pathogenesis of diabetic retinopathy has been largely overlooked. Recent studies suggest that photoreceptors might play a critical role in the diabetes-induced degeneration of retinal capillaries, and thus can no longer be ignored. The present review summarizes diabetes-induced alterations in photoreceptor structure and function, and provides a rationale for further study of a role of photoreceptors in the pathogenesis of the retinopathy.
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Affiliation(s)
- Timothy S Kern
- Case Western Reserve University, Department of Medicine and Center for Diabetes Research Cleveland, Ohio, USA ; Veterans Administration Medical Center Research Service 151 Cleveland, Ohio, USA
| | - Bruce A Berkowitz
- Wayne State University School of Medicine, Departments of Anatomy and Cell Biology and Ophthalmology Detroit, Michigan, USA
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Knoflach D, Schicker K, Glösmann M, Koschak A. Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells. Channels (Austin) 2015; 9:298-306. [PMID: 26274509 PMCID: PMC4826138 DOI: 10.1080/19336950.2015.1078040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/22/2015] [Accepted: 07/22/2015] [Indexed: 10/25/2022] Open
Abstract
Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.4 channel activity affect retinal function is still limited. In the gain-of-function mouse model Cav1.4-IT we expected a reduction in the photoreceptor dynamic range but still transmission toward retinal ganglion cells. A fraction of Cav1.4-IT ganglion cells responded to light stimulation in multielectrode array recordings from whole-mounted retinas, but showed a significantly delayed response onset. Another significant number of cells showed higher activity in darkness. In addition to structural remodeling observed at the first retinal synapse of Cav1.4-IT mice the functional data suggested a loss of contrast enhancement, a fundamental feature of our visual system. In fact, Cav1.4-IT mouse retinas showed a decline in spatial response and changes in their contrast sensitivity profile. Photoreceptor degeneration was obvious from the nodular structure of cone axons and enlarged pedicles which partly moved toward the outer nuclear layer. Loss of photoreceptors was also expressed as reduced expression of proteins involved in chemical and electrical transmission, as such metabotropic glutamate receptor mGluR6 and the gap junction protein Connexin 36. Such gross changes in retinal structure and function could also explain the diminished visual performance of CSNB2 patients. The expression pattern of the plasma-membrane calcium ATPase 1 which participates in the maintenance of the intracellular calcium homeostasis in photoreceptors was changed in Cav1.4-IT mice. This might be part of a protection mechanism against increased calcium influx, as this is suggested for Cav1.4-IT channels.
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Affiliation(s)
- Dagmar Knoflach
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
| | - Klaus Schicker
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
| | | | - Alexandra Koschak
- Medical University Vienna, Center for Physiology and Pharmacology; Department of Neurophysiology and -pharmacology; Vienna, Austria
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology; Innsbruck, Austria
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Lee A, Wang S, Williams B, Hagen J, Scheetz TE, Haeseleer F. Characterization of Cav1.4 complexes (α11.4, β2, and α2δ4) in HEK293T cells and in the retina. J Biol Chem 2014; 290:1505-21. [PMID: 25468907 DOI: 10.1074/jbc.m114.607465] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In photoreceptor synaptic terminals, voltage-gated Cav1.4 channels mediate Ca(2+) signals required for transmission of visual stimuli. Like other high voltage-activated Cav channels, Cav1.4 channels are composed of a main pore-forming Cav1.4 α1 subunit and auxiliary β and α2δ subunits. Of the four distinct classes of β and α2δ, β2 and α2δ4 are thought to co-assemble with Cav1.4 α1 subunits in photoreceptors. However, an understanding of the functional properties of this combination of Cav subunits is lacking. Here, we provide evidence that Cav1.4 α1, β2, and α2δ4 contribute to Cav1.4 channel complexes in the retina and describe their properties in electrophysiological recordings. In addition, we identified a variant of β2, named here β2X13, which, along with β2a, is present in photoreceptor terminals. Cav1.4 α1, β2, and α2δ4 were coimmunoprecipitated from lysates of transfected HEK293 cells and mouse retina and were found to interact in the outer plexiform layer of the retina containing the photoreceptor synaptic terminals, by proximity ligation assays. In whole-cell patch clamp recordings of transfected HEK293T cells, channels (Cav1.4 α1 + β2X13) containing α2δ4 exhibited weaker voltage-dependent activation than those with α2δ1. Moreover, compared with channels (Cav1.4 α1 + α2δ4) with β2a, β2X13-containing channels exhibited greater voltage-dependent inactivation. The latter effect was specific to Cav1.4 because it was not seen for Cav1.2 channels. Our results provide the first detailed functional analysis of the Cav1.4 subunits that form native photoreceptor Cav1.4 channels and indicate potential heterogeneity in these channels conferred by β2a and β2X13 variants.
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Affiliation(s)
- Amy Lee
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology, University of Iowa, Iowa City, Iowa 52242
| | - Shiyi Wang
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology, University of Iowa, Iowa City, Iowa 52242
| | - Brittany Williams
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology, University of Iowa, Iowa City, Iowa 52242
| | - Jussara Hagen
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology, University of Iowa, Iowa City, Iowa 52242
| | - Todd E Scheetz
- the Departments of Ophthalmology and Visual Sciences and Biomedical Engineering, University of Iowa, Iowa City, Iowa 52242, and
| | - Françoise Haeseleer
- the Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
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Ryskamp DA, Redmon S, Jo AO, Križaj D. TRPV1 and Endocannabinoids: Emerging Molecular Signals that Modulate Mammalian Vision. Cells 2014; 3:914-38. [PMID: 25222270 PMCID: PMC4197638 DOI: 10.3390/cells3030914] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/27/2014] [Accepted: 09/05/2014] [Indexed: 01/18/2023] Open
Abstract
Transient Receptor Potential Vanilloid 1 (TRPV1) subunits form a polymodal cation channel responsive to capsaicin, heat, acidity and endogenous metabolites of polyunsaturated fatty acids. While originally reported to serve as a pain and heat detector in the peripheral nervous system, TRPV1 has been implicated in the modulation of blood flow and osmoregulation but also neurotransmission, postsynaptic neuronal excitability and synaptic plasticity within the central nervous system. In addition to its central role in nociception, evidence is accumulating that TRPV1 contributes to stimulus transduction and/or processing in other sensory modalities, including thermosensation, mechanotransduction and vision. For example, TRPV1, in conjunction with intrinsic cannabinoid signaling, might contribute to retinal ganglion cell (RGC) axonal transport and excitability, cytokine release from microglial cells and regulation of retinal vasculature. While excessive TRPV1 activity was proposed to induce RGC excitotoxicity, physiological TRPV1 activity might serve a neuroprotective function within the complex context of retinal endocannabinoid signaling. In this review we evaluate the current evidence for localization and function of TRPV1 channels within the mammalian retina and explore the potential interaction of this intriguing nociceptor with endogenous agonists and modulators.
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Affiliation(s)
- Daniel A Ryskamp
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
| | - Sarah Redmon
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
| | - Andrew O Jo
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
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Jameie SB, Masoumipoor M, Janzadeh A, Nasirinezhad F, Kerdari M, Soleimani M. Combined therapeutic effects of low power laser (980nm) and CoQ10 on Neuropathic Pain in adult male rat. Med J Islam Repub Iran 2014; 28:58. [PMID: 25405124 PMCID: PMC4219887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 10/27/2013] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Neuropathic pain (NP) is one of the most suffering medical conditions that often fail to respond to certain pain therapy. Although its exact etiology is still unknown the role of reactive oxygen species (ROS) and oxidative stress were explored by many researchers. Neuropathies either central or peripheral lead to painful condition as well as social and economic isolation, thus various therapies were used to treat or reduce the pain. Laser therapy and antioxidant drugs have separately considered as treatment for NP, but the combination of them have not been used yet. In order to study the combination effects of Low Level Laser Therapy (LLLT) and Coenzyme Q10 (CoQ10) the present study was designed. METHODS Sixty adult male rats (230-320g) were used in this experimental study that divided into six groups (n=10). Chronic constriction injury (CCI) was used to induce neuropathic pain. The CoQ10 or vehicle, a low level laser of 980nm was used for two consecutive weeks. Thermal and mechanical paw withdrawal thresholds were assessed before and after surgery on 7(th) and 14(th) days. RESULTS As we expected CCI decreased the pain threshold, whereas CoQ10 administration for two weeks increased mechanical and thermal threshold. The same results obtained for laser therapy using the CCI animals. Combination of laser 980nm with CoQ10 also showed significant differences in CCI animals. CONCLUSION Based on our findings the combination of CoQ10 with LLLT showed better effects than each one alone. In this regard we believe that there might be cellular and molecular synergism in simultaneous use of CoQ10 and LLLT on pain relief.
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Affiliation(s)
| | - Masoumeh Masoumipoor
- 2. MSc, Department of Nuclear Engineering, Sciences and Researches branch, Islamic Azad University, Tehran, Iran.
| | - Atousa Janzadeh
- 3. PhD Student of Physiology, Department of Medical Basic Sciences, Faculty of Allied Medicine, Research Center of Physiology & Department of Physiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Farinaz Nasirinezhad
- 4. Associated professor of Physiology, Research Center of Physiology & Department of Physiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Mahdieh Kerdari
- 5. MD, Department of Medical Basic Sciences, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran. .
| | - Maryam Soleimani
- 6. Assistant Professor of Anatomy, Department of Anatomy, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
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Abstract
SIGNIFICANCE Hydrogen sulfide (H2S) has been recognized as a physiological mediator with a variety of functions. It regulates synaptic transmission, vascular tone, inflammation, transcription, and angiogenesis; protects cells from oxidative stress and ischemia-reperfusion injury; and promotes healing of ulcers. RECENT ADVANCES In addition to cystathionine β-synthase and cystathionine γ-lyase, 3-mercaptopyruvate sulfurtransferase along with cysteine aminotransferase was recently demonstrated to produce H2S. Even in bacteria, H2S produced by these enzymes functions as a defense against antibiotics, suggesting that the cytoprotective effect of H2S is a universal defense mechanism in organisms from bacteria to mammals. CRITICAL ISSUES The functional form of H2S-undissociated H2S gas, dissociated HS ion, or some other form of sulfur-has not been identified. FUTURE DIRECTIONS The regulation of H2S production by three enzymes may lead to the identification of the physiological signals that are required to release H2S. The identification of the physiological functions of other forms of sulfur may also help understand the biological significance of H2S.
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Affiliation(s)
- Hideo Kimura
- NCNP, National Institute of Neuroscience , Kodaira, Japan
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Schmitz F. Presynaptic [Ca(2+)] and GCAPs: aspects on the structure and function of photoreceptor ribbon synapses. Front Mol Neurosci 2014; 7:3. [PMID: 24567702 PMCID: PMC3915146 DOI: 10.3389/fnmol.2014.00003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/15/2014] [Indexed: 12/21/2022] Open
Abstract
Changes in intracellular calcium ions [Ca2+] play important roles in photoreceptor signaling. Consequently, intracellular [Ca2+] levels need to be tightly controlled. In the light-sensitive outer segments (OS) of photoreceptors, Ca2+ regulates the activity of retinal guanylate cyclases thus playing a central role in phototransduction and light-adaptation by restoring light-induced decreases in cGMP. In the synaptic terminals, changes of intracellular Ca2+ trigger various aspects of neurotransmission. Photoreceptors employ tonically active ribbon synapses that encode light-induced, graded changes of membrane potential into modulation of continuous synaptic vesicle exocytosis. The active zones of ribbon synapses contain large electron-dense structures, synaptic ribbons, that are associated with large numbers of synaptic vesicles. Synaptic coding at ribbon synapses differs from synaptic coding at conventional (phasic) synapses. Recent studies revealed new insights how synaptic ribbons are involved in this process. This review focuses on the regulation of [Ca2+] in presynaptic photoreceptor terminals and on the function of a particular Ca2+-regulated protein, the neuronal calcium sensor protein GCAP2 (guanylate cyclase-activating protein-2) in the photoreceptor ribbon synapse. GCAP2, an EF-hand-containing protein plays multiple roles in the OS and in the photoreceptor synapse. In the OS, GCAP2 works as a Ca2+-sensor within a Ca2+-regulated feedback loop that adjusts cGMP levels. In the photoreceptor synapse, GCAP2 binds to RIBEYE, a component of synaptic ribbons, and mediates Ca2+-dependent plasticity at that site. Possible mechanisms are discussed.
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Affiliation(s)
- Frank Schmitz
- Department of Neuroanatomy, Institute for Anatomy and Cell Biology, Medical School Homburg/Saar, Saarland University Saarland, Germany
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