101
|
Abstract
The jawless fish that were ancestral to all living vertebrates had four spectral cone types that were probably served by chromatic-opponent retinal circuits. Subsequent evolution of photoreceptor spectral sensitivities is documented for many vertebrate lineages, giving insight into the ecological adaptation of color vision. Beyond the photoreceptors, retinal color processing is best understood in mammals, especially the blueON system, which opposes short- against long-wavelength receptor responses. For other vertebrates that often have three or four types of cone pigment, new findings from zebrafish are extending older work on teleost fish and reptiles to reveal rich color circuitry. Here, horizontal cells establish diverse and complex spectral responses even in photoreceptor outputs. Cone-selective connections to bipolar cells then set up color-opponent synaptic layers in the inner retina, which lead to a large variety of color-opponent channels for transmission to the brain via retinal ganglion cells.
Collapse
Affiliation(s)
- T Baden
- School of Life Sciences, University of Sussex, BN1 9QG Brighton, United Kingdom; ,
- Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany
| | - D Osorio
- School of Life Sciences, University of Sussex, BN1 9QG Brighton, United Kingdom; ,
| |
Collapse
|
102
|
Fu Z, Chen CT, Cagnone G, Heckel E, Sun Y, Cakir B, Tomita Y, Huang S, Li Q, Britton W, Cho SS, Kern TS, Hellström A, Joyal JS, Smith LE. Dyslipidemia in retinal metabolic disorders. EMBO Mol Med 2019; 11:e10473. [PMID: 31486227 PMCID: PMC6783651 DOI: 10.15252/emmm.201910473] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/10/2019] [Accepted: 08/15/2019] [Indexed: 12/24/2022] Open
Abstract
The light‐sensitive photoreceptors in the retina are extremely metabolically demanding and have the highest density of mitochondria of any cell in the body. Both physiological and pathological retinal vascular growth and regression are controlled by photoreceptor energy demands. It is critical to understand the energy demands of photoreceptors and fuel sources supplying them to understand neurovascular diseases. Retinas are very rich in lipids, which are continuously recycled as lipid‐rich photoreceptor outer segments are shed and reformed and dietary intake of lipids modulates retinal lipid composition. Lipids (as well as glucose) are fuel substrates for photoreceptor mitochondria. Dyslipidemia contributes to the development and progression of retinal dysfunction in many eye diseases. Here, we review photoreceptor energy demands with a focus on lipid metabolism in retinal neurovascular disorders.
Collapse
Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA.,Manton Center for Orphan Disease, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Chuck T Chen
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Gael Cagnone
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Emilie Heckel
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Ye Sun
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Bertan Cakir
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Yohei Tomita
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Shuo Huang
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Qian Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - William Britton
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Steve S Cho
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| | - Timothy S Kern
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Irvine, CA, USA
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Jean-Sébastien Joyal
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, QC, Canada.,Department of Pharmacology and Therapeutics, University of Montreal, Montreal, QC, Canada
| | - Lois Eh Smith
- Department of Ophthalmology, Harvard Medical School, Boston Children's Hospital, Boston, MA, USA
| |
Collapse
|
103
|
Dizhoor AM, Olshevskaya EV, Peshenko IV. Retinal guanylyl cyclase activation by calcium sensor proteins mediates photoreceptor degeneration in an rd3 mouse model of congenital human blindness. J Biol Chem 2019; 294:13729-13739. [PMID: 31346032 DOI: 10.1074/jbc.ra119.009948] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/22/2019] [Indexed: 01/19/2023] Open
Abstract
Deficiency of RD3 (retinal degeneration 3) protein causes recessive blindness and photoreceptor degeneration in humans and in the rd3 mouse strain, but the disease mechanism is unclear. Here, we present evidence that RD3 protects photoreceptors from degeneration by competing with guanylyl cyclase-activating proteins (GCAPs), which are calcium sensor proteins for retinal membrane guanylyl cyclase (RetGC). RetGC activity in rd3/rd3 retinas was drastically reduced but stimulated by the endogenous GCAPs at low Ca2+ concentrations. RetGC activity completely failed to accelerate in rd3/rd3GCAPs -/- hybrid photoreceptors, whose photoresponses remained drastically suppressed compared with the WT. However, ∼70% of the hybrid rd3/rd3GCAPs -/- photoreceptors survived past 6 months, in stark contrast to <5% in the nonhybrid rd3/rd3 retinas. GFP-tagged human RD3 inhibited GCAP-dependent activation of RetGC in vitro similarly to the untagged RD3. When transgenically expressed in rd3/rd3 mouse retinas under control of the rhodopsin promoter, the RD3GFP construct increased RetGC levels to near normal levels, restored dark-adapted photoresponses, and rescued rods from degeneration. The fluorescence of RD3GFP in rd3/rd3RD3GFP + retinas was mostly restricted to the rod photoreceptor inner segments, whereas GCAP1 immunofluorescence was concentrated predominantly in the outer segment. However, RD3GFP became distributed to the outer segments when bred into a GCAPs -/- genetic background. These results support the hypothesis that an essential biological function of RD3 is competition with GCAPs that inhibits premature cyclase activation in the inner segment. Our findings also indicate that the fast rate of degeneration in RD3-deficient photoreceptors results from the lack of this inhibition.
Collapse
Affiliation(s)
- Alexander M Dizhoor
- Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Elena V Olshevskaya
- Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Igor V Peshenko
- Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| |
Collapse
|
104
|
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.
Collapse
|
105
|
Chen HY, Welby E, Li T, Swaroop A. Retinal disease in ciliopathies: Recent advances with a focus on stem cell-based therapies. ACTA ACUST UNITED AC 2019; 4:97-115. [PMID: 31763178 PMCID: PMC6839492 DOI: 10.3233/trd-190038] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ciliopathies display extensive genetic and clinical heterogeneity, varying in severity, age of onset, disease progression and organ systems affected. Retinal involvement, as demonstrated by photoreceptor dysfunction or death, is a highly penetrant phenotype among a vast majority of ciliopathies. Photoreceptor cells possess a specialized and modified sensory cilium with membrane discs where efficient photon capture and ensuing signaling cascade initiate the visual process. Disruptions of cilia biogenesis and protein transport lead to impairment of photoreceptor function and eventually degeneration. Despite advances in elucidation of ciliogenesis and photoreceptor cilia defects, we have limited understanding of pathogenic mechanisms underlying retinal phenotype(s) observed in human ciliopathies. Patient-derived induced pluripotent stem cell (iPSC)-based approaches offer a unique opportunity to complement studies with model organisms and examine cilia disease relevant to humans. Three-dimensional retinal organoids from iPSC lines feature laminated cytoarchitecture, apical-basal polarity and emergence of a ciliary structure, thereby permitting pathogenic modeling of human photoreceptors in vitro. Here, we review the biology of photoreceptor cilia and associated defects and discuss recent progress in evolving treatment modalities, especially using patient-derived iPSCs, for retinal ciliopathies.
Collapse
Affiliation(s)
- Holly Yu Chen
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Emily Welby
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tiansen Li
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
106
|
Hu Y, Wang X, Hu B, Mao Y, Chen Y, Yan L, Yong J, Dong J, Wei Y, Wang W, Wen L, Qiao J, Tang F. Dissecting the transcriptome landscape of the human fetal neural retina and retinal pigment epithelium by single-cell RNA-seq analysis. PLoS Biol 2019; 17:e3000365. [PMID: 31269016 PMCID: PMC6634428 DOI: 10.1371/journal.pbio.3000365] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 07/16/2019] [Accepted: 06/25/2019] [Indexed: 12/21/2022] Open
Abstract
The developmental pathway of the neural retina (NR) and retinal pigment epithelium (RPE) has been revealed by extensive research in mice. However, the molecular mechanisms underlying the development of the human NR and RPE, as well as the interactions between these two tissues, have not been well defined. Here, we analyzed 2,421 individual cells from human fetal NR and RPE using single-cell RNA sequencing (RNA-seq) technique and revealed the tightly regulated spatiotemporal gene expression network of human retinal cells. We identified major cell classes of human fetal retina and potential crucial transcription factors for each cell class. We dissected the dynamic expression patterns of visual cycle- and ligand-receptor interaction-related genes in the RPE and NR. Moreover, we provided a map of disease-related genes for human fetal retinal cells and highlighted the importance of retinal progenitor cells as potential targets of inherited retinal diseases. Our findings captured the key in vivo features of the development of the human NR and RPE and offered insightful clues for further functional studies.
Collapse
Affiliation(s)
- Yuqiong Hu
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
| | - Xiaoye Wang
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Boqiang Hu
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
| | - Yunuo Mao
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
| | - Yidong Chen
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Liying Yan
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Jun Yong
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Ji Dong
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
| | - Yuan Wei
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Wei Wang
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
| | - Lu Wen
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
| | - Jie Qiao
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Fuchou Tang
- Beijing Advanced Innovation Center for Genomics, Department of Obstetrics and Gynecology, Third Hospital, College of Life Sciences, Peking University, Beijing, China
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Biomedical Pioneering Innovation Center, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| |
Collapse
|
107
|
Hanke-Gogokhia C, Frederick JM, Zhang H, Baehr W. Binary Function of ARL3-GTP Revealed by Gene Knockouts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:317-325. [PMID: 29721959 DOI: 10.1007/978-3-319-75402-4_39] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
UNC119 and PDEδ are lipid-binding proteins and are thought to form diffusible complexes with transducin-α and prenylated OS proteins, respectively, to mediate their trafficking to photoreceptor outer segments. Here, we investigate mechanisms of trafficking which are controlled by Arf-like protein 3 (Arl3), a small GTPase. The activity of ARL3 is regulated by a GEF (ARL13b) and a GAP (RP2). In a mouse germline knockout of RP2, ARL3-GTP is abundant as its intrinsic GTPase activity is extremely low. High levels of ARL3-GTP impair binding and trafficking of cargo to the outer segment. Germline knockout of ARL3 is embryonically lethal generating a syndromic ciliopathy-like phenotype. Retina- and rod-specific knockout of ARL3 allow to determine the precise mechanisms leading to photoreceptor degeneration. The knockouts reveal binary functions of ARL3-GTP as a key molecule in late-stage photoreceptor ciliogenesis and cargo displacement factor.
Collapse
Affiliation(s)
- Christin Hanke-Gogokhia
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA. .,Department of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
| | - Jeanne M Frederick
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Houbin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study, The Institute of Laboratory Medicine, Hospital of University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China.,School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Wolfgang Baehr
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA. .,Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA. .,Department of Biology, University of Utah, Salt Lake City, UT, USA.
| |
Collapse
|
108
|
Liu H, Tang J, Du Y, Saadane A, Samuels I, Veenstra A, Kiser JZ, Palczewski K, Kern TS. Transducin1, Phototransduction and the Development of Early Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2019; 60:1538-1546. [PMID: 30994864 PMCID: PMC6736377 DOI: 10.1167/iovs.18-26433] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/14/2019] [Indexed: 12/31/2022] Open
Abstract
Purpose Recent evidence suggests that retinal photoreceptor cells have an important role in the pathogenesis of retinal microvascular lesions in diabetes. We investigated the role of rod cell phototransduction on the pathogenesis of early diabetic retinopathy (DR) using Gnat1-/- mice (which causes permanent inhibition of phototransduction in rod cells without degeneration). Methods Retinal thickness, oxidative stress, expression of inflammatory proteins, electroretinograms (ERG) and optokinetic responses, and capillary permeability and degeneration were evaluated at up to 8 months of diabetes. Results The diabetes-induced degeneration of retinal capillaries was significantly inhibited in the Gnat1-/- diabetics. The effect of the Gnat1 deletion on the diabetes-induced increase in permeability showed a nonuniform accumulation of albumin in the neural retina; the defect was inhibited in diabetic Gnat1-/- mice in the inner plexiform layer (IPL), but neither in the outer plexiform (OPL) nor inner nuclear (INL) layers. In Gnat1-deficient animals, the diabetes-induced increase in expression of inflammatory associated proteins (iNOS and ICAM-1, and phosphorylation of IĸB) in the retina, and the leukocyte mediated killing of retinal endothelial cells were inhibited, however the diabetes-mediated induction of oxidative stress was not inhibited. Conclusions In conclusion, deletion of transducin1 (and the resulting inhibition of phototransduction in rod cells) inhibits the development of retinal vascular pathology in early DR.
Collapse
Affiliation(s)
- Haitao Liu
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jie Tang
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Yunpeng Du
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Aicha Saadane
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Ivy Samuels
- Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, United States
- Department of Ophthalmic Research, Cleveland Clinic, Cleveland, Ohio, United States
| | - Alex Veenstra
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jianying Z. Kiser
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
- Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, United States
| | - Timothy S. Kern
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
- Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, United States
- Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, United States
| |
Collapse
|
109
|
Modeling and simulation of phototransduction cascade in vertebrate rod photoreceptors. BMC Ophthalmol 2019; 19:55. [PMID: 30786871 PMCID: PMC6381673 DOI: 10.1186/s12886-019-1048-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/24/2019] [Indexed: 11/21/2022] Open
Abstract
Background The activation of phototransduction cascade in rod photoreceptors has been well studied in literature, but there is a lack of a mature kinetic model structure covering both the activation and inactivation processes. Methods In this work, a kinetic model structure is developed to describe the major activation and inactivation processes in vertebrate rod photoreceptors with the electroretinogram (ERG) as output. Simulation was performed to validate developed model structure. Results The developed model structure could fit experimental data with small error. Conclusions The result indicated that the developed model structure could show the inactivation process of phototransduction cascades in the rod photoreceptors.
Collapse
|
110
|
Peshenko IV, Yu Q, Lim S, Cudia D, Dizhoor AM, Ames JB. Retinal degeneration 3 (RD3) protein, a retinal guanylyl cyclase regulator, forms a monomeric and elongated four-helix bundle. J Biol Chem 2019; 294:2318-2328. [PMID: 30559291 PMCID: PMC6378972 DOI: 10.1074/jbc.ra118.006106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/07/2018] [Indexed: 12/20/2022] Open
Abstract
Retinal degeneration 3 (RD3) protein promotes accumulation of retinal membrane guanylyl cyclase (RetGC) in the photoreceptor outer segment and suppresses RetGC activation by guanylyl cyclase-activating proteins (GCAPs). Mutations truncating RD3 cause severe congenital blindness by preventing the inhibitory binding of RD3 to the cyclase. The high propensity of RD3 to aggregate in solution has prevented structural analysis. Here, we produced a highly soluble variant of human RD3 (residues 18-160) that is monomeric and can still bind and negatively regulate RetGC. The NMR solution structure of RD3 revealed an elongated backbone structure (70 Å long and 30 Å wide) consisting of a four-helix bundle with a long unstructured loop between helices 1 and 2. The structure reveals that RD3 residues previously implicated in the RetGC binding map to a localized and contiguous area on the structure, involving a loop between helices 2 and 3 and adjacent parts of helices 3 and 4. The NMR structure of RD3 was validated by mutagenesis. Introducing Trp85 or Phe29 to replace Cys or Leu, respectively, disrupts packing in the hydrophobic core and lowers RD3's apparent affinity for RetGC1. Introducing a positive charge at the interface (Glu32 to Lys) also lowered the affinity. Conversely, introducing Val in place of Cys93 stabilized the hydrophobic core and increased the RD3 affinity for the cyclase. The NMR structure of RD3 presented here provides a structural basis for elucidating RD3-RetGC interactions relevant for normal vision or blindness.
Collapse
Affiliation(s)
- Igor V Peshenko
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027 and
| | - Qinhong Yu
- the Department of Chemistry, University of California, Davis, California 95616
| | - Sunghyuk Lim
- the Department of Chemistry, University of California, Davis, California 95616
| | - Diana Cudia
- the Department of Chemistry, University of California, Davis, California 95616
| | - Alexander M Dizhoor
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027 and
| | - James B Ames
- the Department of Chemistry, University of California, Davis, California 95616
| |
Collapse
|
111
|
Stem cell-based retina models. Adv Drug Deliv Rev 2019; 140:33-50. [PMID: 29777757 DOI: 10.1016/j.addr.2018.05.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/16/2018] [Accepted: 05/12/2018] [Indexed: 12/23/2022]
Abstract
From the early days of cell biological research, the eye-especially the retina-has evoked broad interest among scientists. The retina has since been thoroughly investigated and numerous models have been exploited to shed light on its development, morphology, and function. Apart from various animal models and human clinical and anatomical research, stem cell-based models of animal and human cells of origin have entered the field, especially during the last decade. Despite the observation that the retina of different species comprises endogenous stem cells, most stem cell-related research in the human retina is now based on pluripotent stem cell models. Herein, systems of two-dimensional (2D) cultures and co-cultures of distinctly differentiated retinal subtypes revealed a variety of cellular aspects but have in many aspects been replaced by three-dimensional (3D) structures-the so-called retinal organoids. These organoids not only contain all major retinal cell subtypes compared to the physiological situation, but also show a distinct layering in close proximity to the in vivo morphology. Nevertheless, all these models have inherent advantages and disadvantages, which are expounded and summarized in this review. Finally, we discuss current application aspects of stem cell-based retina models and the specific promises they hold for the future.
Collapse
|
112
|
Abstract
The study of taste has been guided throughout much of its history by the conceptual framework of psychophysics, where the focus was on quantification of the subjective experience of the taste sensations. By the mid-20th century, data from physiologic studies had accumulated sufficiently to assemble a model for the function of receptors that must mediate the initial stimulus of tastant molecules in contact with the tongue. But the study of taste as a receptor-mediated event did not gain momentum until decades later when the actual receptor proteins and attendant signaling mechanisms were identified and localized to the highly specialized taste-responsive cells of the tongue. With those discoveries a new opportunity to examine taste as a function of receptor activity has come into focus. Pharmacology is the science designed specifically for the experimental interrogation and quantitative characterization of receptor function at all levels of inquiry from molecules to behavior. This review covers the history of some of the major concepts that have shaped thinking and experimental approaches to taste, the seminal discoveries that have led to elucidation of receptors for taste, and how applying principles of receptor pharmacology can enhance understanding of the mechanisms of taste physiology and perception.
Collapse
Affiliation(s)
- R Kyle Palmer
- Opertech Bio, Inc., Pennovation Center, Philadelphia, Pennsylvania
| |
Collapse
|
113
|
Peshenko IV, Cideciyan AV, Sumaroka A, Olshevskaya EV, Scholten A, Abbas S, Koch KW, Jacobson SG, Dizhoor AM. A G86R mutation in the calcium-sensor protein GCAP1 alters regulation of retinal guanylyl cyclase and causes dominant cone-rod degeneration. J Biol Chem 2019; 294:3476-3488. [PMID: 30622141 DOI: 10.1074/jbc.ra118.006180] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/04/2019] [Indexed: 11/06/2022] Open
Abstract
The guanylyl cyclase-activating protein, GCAP1, activates photoreceptor membrane guanylyl cyclase (RetGC) in the light, when free Ca2+ concentrations decline, and decelerates the cyclase in the dark, when Ca2+ concentrations rise. Here, we report a novel mutation, G86R, in the GCAP1 (GUCA1A) gene in a family with a dominant retinopathy. The G86R substitution in a "hinge" region connecting EF-hand domains 2 and 3 in GCAP1 strongly interfered with its Ca2+-dependent activator-to-inhibitor conformational transition. The G86R-GCAP1 variant activated RetGC at low Ca2+ concentrations with higher affinity than did the WT GCAP1, but failed to decelerate the cyclase at the Ca2+ concentrations characteristic of dark-adapted photoreceptors. Ca2+-dependent increase in Trp94 fluorescence, indicative of the GCAP1 transition to its RetGC inhibiting state, was suppressed and shifted to a higher Ca2+ range. Conformational changes in G86R GCAP1 detectable by isothermal titration calorimetry (ITC) also became less sensitive to Ca2+, and the dose dependence of the G86R GCAP1-RetGC1 complex inhibition by retinal degeneration 3 (RD3) protein was shifted toward higher than normal concentrations. Our results indicate that the flexibility of the hinge region between EF-hands 2 and 3 is required for placing GCAP1-regulated Ca2+ sensitivity of the cyclase within the physiological range of intracellular Ca2+ at the expense of reducing GCAP1 affinity for the target enzyme. The disease-linked mutation of the hinge Gly86, leading to abnormally high affinity for the target enzyme and reduced Ca2+ sensitivity of GCAP1, is predicted to abnormally elevate cGMP production and Ca2+ influx in photoreceptors in the dark.
Collapse
Affiliation(s)
- Igor V Peshenko
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Artur V Cideciyan
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Alexander Sumaroka
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Elena V Olshevskaya
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Alexander Scholten
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Seher Abbas
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Karl-Wilhelm Koch
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Samuel G Jacobson
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Alexander M Dizhoor
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027,
| |
Collapse
|
114
|
Lu Y, Benedetti J, Yao X. Light-Induced Length Shrinkage of Rod Photoreceptor Outer Segments. Transl Vis Sci Technol 2018; 7:29. [PMID: 30619649 PMCID: PMC6314056 DOI: 10.1167/tvst.7.6.29] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022] Open
Abstract
Purpose This study was designed to verify light-induced outer segment (OS) length shrinkage of rod photoreceptors and to characterize its anatomic source at disc-level resolution. Methods Frog (Rana pipiens) retinas were used for this study. Time-lapse light microscopy of freshly isolated OSs was employed to test transient rod OS changes at 10 ms temporal resolution. Histological light microscopy of dark- and light-adapted retinas was used to confirm light-induced rod OS length changes; and transmission electron microscopy (TEM) was used to quantify light-driven structural perturbation of rod OSs at disc level resolution. Results Time-lapse light microscopy images verified transient length shrinking responses in freshly isolated rod OSs. Histological light microscopy images confirmed reduced rod OS lengths in light-adapted retinas, compared to that of dark-adapted retinas. TEM images disclosed shortened inter-disc distances in light-adapted retinas compared to dark-adapted retinas. Conclusions Light-induced rod OS length shrinkage was confirmed using time-lapse light microscopy of isolated rod OSs and histological light microscopy of dark- and light-adapted retinas. TEM revealed that the rod OS length shrinkage was correlated to the light-driven decrease of the space between individual discs, not the disc thickness itself. Translational Relevance Light-induced transient rod response promises a noninvasive biomarker for early diagnosis of age-related macular degeneration and retinitis pigmentosa, in which the rod photoreceptors are known to be more vulnerable than cone photoreceptors.
Collapse
Affiliation(s)
- Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Jacopo Benedetti
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.,Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, USA
| |
Collapse
|
115
|
Sokolov M, Yadav RP, Brooks C, Artemyev NO. Chaperones and retinal disorders. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2018; 114:85-117. [PMID: 30635087 DOI: 10.1016/bs.apcsb.2018.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Defects in protein folding and trafficking are a common cause of photoreceptor degeneration, causing blindness. Photoreceptor cells present an unusual challenge to the protein folding and transport machinery due to the high rate of protein synthesis, trafficking and the renewal of the outer segment, a primary cilium that has been modified into a specialized light-sensing compartment. Phototransduction components, such as rhodopsin and cGMP-phosphodiesterase, and multimeric ciliary transport complexes, such as the BBSome, are hotspots for mutations that disrupt proteostasis and lead to the death of photoreceptors. In this chapter, we review recent studies that advance our understanding of the chaperone and transport machinery of phototransduction proteins.
Collapse
Affiliation(s)
- Maxim Sokolov
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Celine Brooks
- Department of Ophthalmology, West Virginia University, Morgantown, WV, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA, United States.
| |
Collapse
|
116
|
Lahne M, Piekos SM, O'Neill J, Ackerman KM, Hyde DR. Photo-regulation of rod precursor cell proliferation. Exp Eye Res 2018; 178:148-159. [PMID: 30267656 DOI: 10.1016/j.exer.2018.09.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 09/18/2018] [Accepted: 09/26/2018] [Indexed: 11/29/2022]
Abstract
Teleosts are unique in their ability to undergo persistent neurogenesis and to regenerate damaged and lost retinal neurons in adults. This contrasts with the human retina, which is incapable of replacing lost retinal neurons causing vision loss/blindness in the affected individuals. Two cell populations within the adult teleost retina generate new retinal neurons throughout life. Stem cells within the ciliary marginal zone give rise to all retinal cell types except for rod photoreceptors, which are produced by the resident Müller glia that are located within the inner nuclear layer of the entire retina. Understanding the mechanisms that regulate the generation of photoreceptors in the adult teleost retina may ultimately aid developing strategies to overcome vision loss in diseases such as retinitis pigmentosa. Here, we investigated whether photic deprivation alters the proliferative capacity of rod precursor cells, which are generated from Müller glia. In dark-adapted retinas, rod precursor cell proliferation increased, while the number of proliferating Müller glia and their derived olig2:EGFP-positive neuronal progenitor cells was not significantly changed. Cell death of rod photoreceptors was excluded as the inducer of rod precursor cell proliferation, as the number of TUNEL-positive cells and l-plastin-positive microglia in both the outer (ONL) and inner nuclear layer (INL) remained at a similar level throughout the dark-adaptation timecourse. Rod precursor cell proliferation in response to dark-adaptation was characterized by an increased number of EdU-positive cells, i.e. cells that were undergoing DNA replication. These proliferating rod precursor cells in dark-adapted zebrafish differentiated into rod photoreceptors at a comparable percentage and in a similar time frame as those maintained under standard light conditions suggesting that the cell cycle did not stall in dark-adapted retinas. Inhibition of IGF1-receptor signaling reduced the dark-adaptation-mediated proliferation response; however, caloric restriction which has been suggested to be integrated by the IGF1/growth hormone signaling axis did not influence rod precursor cell proliferation in dark-adapted retinas, as similar numbers were observed in starved and normal fed zebrafish. In summary, photic deprivation induces cell cycle entry of rod precursor cells via IGF1-receptor signaling independent of Müller glia proliferation.
Collapse
Affiliation(s)
- Manuela Lahne
- Department of Biological Sciences, The Center for Stem Cells and Regenerative Medicine and The Center for Zebrafish Research, Galvin Life Sciences Building, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Samantha M Piekos
- Department of Biological Sciences, The Center for Stem Cells and Regenerative Medicine and The Center for Zebrafish Research, Galvin Life Sciences Building, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - John O'Neill
- Department of Biological Sciences, The Center for Stem Cells and Regenerative Medicine and The Center for Zebrafish Research, Galvin Life Sciences Building, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Kristin M Ackerman
- Department of Biological Sciences, The Center for Stem Cells and Regenerative Medicine and The Center for Zebrafish Research, Galvin Life Sciences Building, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - David R Hyde
- Department of Biological Sciences, The Center for Stem Cells and Regenerative Medicine and The Center for Zebrafish Research, Galvin Life Sciences Building, University of Notre Dame, Notre Dame, IN, 46556, USA.
| |
Collapse
|
117
|
Milano SK, Wang C, Erickson JW, Cerione RA, Ramachandran S. Gain-of-function screen of α-transducin identifies an essential phenylalanine residue necessary for full effector activation. J Biol Chem 2018; 293:17941-17952. [PMID: 30266806 DOI: 10.1074/jbc.ra118.003746] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 09/21/2018] [Indexed: 11/06/2022] Open
Abstract
Two regions on the α subunits of heterotrimeric GTP-binding proteins (G-proteins), the Switch II/α2 helix (which changes conformation upon GDP-GTP exchange) and the α3 helix, have been shown to contain the binding sites for their effector proteins. However, how the binding of Gα subunits to their effector proteins is translated into the stimulation of effector activity is still poorly understood. Here, we took advantage of a reconstituted rhodopsin-coupled phototransduction system to address this question and identified a distinct surface and an essential residue on the α subunit of the G-protein transducin (αT) that is necessary to fully activate its effector enzyme, the cGMP phosphodiesterase (PDE). We started with a chimeric G-protein α subunit (αT*) comprising residues mainly from αT and a short stretch of residues from the Gi1 α subunit (αi1), which only weakly stimulates PDE activity. We then reinstated the αT residues by systematically replacing the corresponding αi1 residues within αT* with the aim of fully restoring PDE stimulatory activity. These experiments revealed that the αG/α4 loop and a phenylalanine residue at position 283 are essential for conferring the αT* subunit with full PDE stimulatory capability. We further demonstrated that this same region and amino acid within the α subunit of the Gs protein (αs) are necessary for full adenylyl cyclase activation. These findings highlight the importance of the αG/α4 loop and of an essential phenylalanine residue within this region on Gα subunits αT and αs as being pivotal for their selective and optimal stimulation of effector activity.
Collapse
Affiliation(s)
- Shawn K Milano
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301
| | - Chenyue Wang
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301
| | - Jon W Erickson
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301
| | - Richard A Cerione
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301; Department of Molecular Medicine, Cornell University, Ithaca, New York 14853-6401.
| | - Sekar Ramachandran
- From the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
118
|
Examining the Role of Cone-expressed RPE65 in Mouse Cone Function. Sci Rep 2018; 8:14201. [PMID: 30242264 PMCID: PMC6155087 DOI: 10.1038/s41598-018-32667-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/13/2018] [Indexed: 11/08/2022] Open
Abstract
Efficient chromophore supply is paramount for the continuous function of vertebrate cone photoreceptors. It is well established that isomerization of all-trans- to 11-cis- retinoid in the retinal pigmented epithelium by RPE65 is a key reaction in this process. Mutations in RPE65 result in a disrupted chromophore supply, retinal degeneration, and blindness. Interestingly, RPE65 has recently been found to also be expressed in cone photoreceptors in several species, including mouse and human. However, the functional role of cone-expressed RPE65 has remained unknown. Here, we used loss and gain of function approaches to investigate this issue. First, we compared the function of cones from control and RPE65-deficient mice. Although we found that deletion of RPE65 partially suppressed cone dark adaptation, the interpretation of this result was complicated by the abnormal cone structure and function caused by the chromophore deficiency in the absence of RPE65 in the pigmented epithelium. As an alternative approach, we generated transgenic mice to express human RPE65 in the cones of mice where RPE65 expression is normally restricted to the pigmented epithelium. Comparison of control (RPE65-deficient) and transgenic (RPE65-expressing) cones revealed no morphological or functional changes, with only a slight delay in dark adaptation, possibly caused by the buffering of retinoids by RPE65. Together, our results do not provide any evidence for a functional role of RPE65 in mouse cones. Future studies will have to determine whether cone-expressed RPE65 plays a role in maintaining the long-term homeostasis of retinoids in cones and their function and survival, particularly in humans.
Collapse
|
119
|
Hardcastle AJ, Sieving PA, Sahel JA, Jacobson SG, Cideciyan AV, Flannery JG, Beltran WA, Aguirre GD. Translational Retinal Research and Therapies. Transl Vis Sci Technol 2018; 7:8. [PMID: 30225158 PMCID: PMC6138060 DOI: 10.1167/tvst.7.5.8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/13/2018] [Indexed: 01/01/2023] Open
Abstract
The following review summarizes the state of the art in representative aspects of gene therapy/translational medicine and evolves from a symposium held at the School of Veterinary Medicine, University of Pennsylvania on November 16, 2017 honoring Dr. Gustavo Aguirre, recipient of ARVO's 2017 Proctor Medal. Focusing on the retina, speakers highlighted current work on moving therapies for inherited retinal degenerative diseases from the laboratory bench to the clinic.
Collapse
Affiliation(s)
| | - Paul A Sieving
- Director, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Director of the UPMC Eye Center, University of Pittsburgh Medical Center, Pittsburgh, PA, USA and Director, Institut de la Vision, Sorbonne Université-Inserm-CNRS, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - John G Flannery
- Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
| | - William A Beltran
- Department of Clinical Sciences and Advanced Medicine, Division of Experimental Retinal Therapies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gustavo D Aguirre
- Department of Clinical Sciences and Advanced Medicine, Division of Experimental Retinal Therapies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
120
|
Palczewska G, Stremplewski P, Suh S, Alexander N, Salom D, Dong Z, Ruminski D, Choi EH, Sears AE, Kern TS, Wojtkowski M, Palczewski K. Two-photon imaging of the mammalian retina with ultrafast pulsing laser. JCI Insight 2018; 3:121555. [PMID: 30185665 DOI: 10.1172/jci.insight.121555] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022] Open
Abstract
Noninvasive imaging of visual system components in vivo is critical for understanding the causal mechanisms of retinal diseases and for developing therapies for their treatment. However, ultraviolet light needed to excite endogenous fluorophores that participate in metabolic processes of the retina is highly attenuated by the anterior segment of the human eye. In contrast, 2-photon excitation fluorescence imaging with pulsed infrared light overcomes this obstacle. Reducing retinal exposure to laser radiation remains a major barrier in advancing this technology to studies in humans. To increase fluorescence intensity and reduce the requisite laser power, we modulated ultrashort laser pulses with high-order dispersion compensation and applied sensorless adaptive optics and custom image recovery software and observed an over 300% increase in fluorescence of endogenous retinal fluorophores when laser pulses were shortened from 75 fs to 20 fs. No functional or structural changes to the retina were detected after exposure to 2-photon excitation imaging light with 20-fs pulses. Moreover, wide bandwidth associated with short pulses enables excitation of multiple fluorophores with different absorption spectra and thus can provide information about their relative changes and intracellular distribution. These data constitute a substantial advancement for safe 2-photon fluorescence imaging of the human eye.
Collapse
Affiliation(s)
| | - Patrycjusz Stremplewski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Susie Suh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nathan Alexander
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - David Salom
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Zhiqian Dong
- Polgenix, Inc., Department of Medical Devices, Cleveland, Ohio, USA
| | - Daniel Ruminski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Elliot H Choi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Avery E Sears
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Timothy S Kern
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Maciej Wojtkowski
- Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| |
Collapse
|
121
|
Xu CL, Park KS, Tsang SH. CRISPR/Cas9 genome surgery for retinal diseases. DRUG DISCOVERY TODAY. TECHNOLOGIES 2018; 28:23-32. [PMID: 30205877 DOI: 10.1016/j.ddtec.2018.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/17/2018] [Accepted: 05/29/2018] [Indexed: 12/25/2022]
Abstract
Retinal diseases that impair vision can impose heavy physical and emotional burdens on patients' lives. Currently, clustered regularly interspaced short palindromic repeats (CRISPR) is a prevalent gene-editing tool that can be harnessed to generate disease model organisms for specific retinal diseases, which are useful for elucidating pathophysiology and revealing important links between genetic mutations and phenotypic defects. These retinal disease models are fundamental for testing various therapies and are indispensible for potential future clinical trials. CRISPR-mediated procedures involving CRISPR-associated protein 9 (Cas9) may also be used to edit genome sequences and correct mutations. Thus, if used for future therapies, CRISPR/Cas9 genome surgery could eliminate the need for patients with retinal diseases to undergo repetitive procedures such as drug injections. In this review, we will provide an overview of CRISPR/Cas9, discuss the different types of Cas9, and compare Cas9 to other endonucleases. Furthermore, we will explore the many ways in which researchers are currently utilizing this versatile tool, as CRISPR/Cas9 may have far-reaching effects in the treatment of retinal diseases.
Collapse
Affiliation(s)
- Christine L Xu
- Edward S Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA; Jonas Children's Vision Care and the Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Karen Sophia Park
- Edward S Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA; Jonas Children's Vision Care and the Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Stephen H Tsang
- Edward S Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA; Jonas Children's Vision Care and the Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA; Department of Pathology & Cell Biology, Institute of Human Nutrition, Columbia Stem Cell Initiative, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| |
Collapse
|
122
|
Vinberg F, Chen J, Kefalov VJ. Regulation of calcium homeostasis in the outer segments of rod and cone photoreceptors. Prog Retin Eye Res 2018; 67:87-101. [PMID: 29883715 DOI: 10.1016/j.preteyeres.2018.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/30/2018] [Accepted: 06/04/2018] [Indexed: 12/11/2022]
Abstract
Calcium plays important roles in the function and survival of rod and cone photoreceptor cells. Rapid regulation of calcium in the outer segments of photoreceptors is required for the modulation of phototransduction that drives the termination of the flash response as well as light adaptation in rods and cones. On a slower time scale, maintaining proper calcium homeostasis is critical for the health and survival of photoreceptors. Decades of work have established that the level of calcium in the outer segments of rods and cones is regulated by a dynamic equilibrium between influx via the transduction cGMP-gated channels and extrusion via rod- and cone-specific Na+/Ca2+, K+ exchangers (NCKXs). It had been widely accepted that the only mechanism for extrusion of calcium from rod outer segments is via the rod-specific NCKX1, while extrusion from cone outer segments is driven exclusively by the cone-specific NCKX2. However, recent evidence from mice lacking NCKX1 and NCKX2 have challenged that notion and have revealed a more complex picture, including a NCKX-independent mechanism in rods and two separate NCKX-dependent mechanisms in cones. This review will focus on recent findings on the molecular mechanisms of extrusion of calcium from the outer segments of rod and cone photoreceptors, and the functional and structural changes in photoreceptors when normal extrusion is disrupted.
Collapse
Affiliation(s)
- Frans Vinberg
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA; John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
| | - Vladimir J Kefalov
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.
| |
Collapse
|
123
|
Kovary KM, Taylor B, Zhao ML, Teruel MN. Expression variation and covariation impair analog and enable binary signaling control. Mol Syst Biol 2018; 14:e7997. [PMID: 29759982 PMCID: PMC5951153 DOI: 10.15252/msb.20177997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 03/26/2018] [Accepted: 04/05/2018] [Indexed: 11/09/2022] Open
Abstract
Due to noise in the synthesis and degradation of proteins, the concentrations of individual vertebrate signaling proteins were estimated to vary with a coefficient of variation (CV) of approximately 25% between cells. Such high variation is beneficial for population-level regulation of cell functions but abolishes accurate single-cell signal transmission. Here, we measure cell-to-cell variability of relative protein abundance using quantitative proteomics of individual Xenopus laevis eggs and cultured human cells and show that variation is typically much lower, in the range of 5-15%, compatible with accurate single-cell transmission. Focusing on bimodal ERK signaling, we show that variation and covariation in MEK and ERK expression improves controllability of the percentage of activated cells, demonstrating how variation and covariation in expression enables population-level control of binary cell-fate decisions. Together, our study argues for a control principle whereby low expression variation enables accurate control of analog single-cell signaling, while increased variation, covariation, and numbers of pathway components are required to widen the stimulus range over which external inputs regulate binary cell activation to enable precise control of the fraction of activated cells in a population.
Collapse
Affiliation(s)
- Kyle M Kovary
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Brooks Taylor
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Michael L Zhao
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Mary N Teruel
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| |
Collapse
|
124
|
Lu Y, Liu C, Yao X. In vivo super-resolution imaging of transient retinal phototropism evoked by oblique light stimulation. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-4. [PMID: 29752801 PMCID: PMC5946809 DOI: 10.1117/1.jbo.23.5.050502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 04/19/2018] [Indexed: 05/28/2023]
Abstract
Rod-dominated transient retinal phototropism (TRP) has been observed in freshly isolated retinas, promising a noninvasive biomarker for objective assessment of retinal physiology. However, in vivo mapping of TRP is challenging due to its subcellular signal magnitude and fast time course. We report here a virtually structured detection-based super-resolution ophthalmoscope to achieve subcellular spatial resolution and millisecond temporal resolution for in vivo imaging of TRP. Spatiotemporal properties of in vivo TRP were characterized corresponding to variable light intensity stimuli, confirming that TRP is tightly correlated with early stages of phototransduction.
Collapse
Affiliation(s)
- Yiming Lu
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
| | - Changgeng Liu
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
| | - Xincheng Yao
- University of Illinois at Chicago, Department of Bioengineering, Chicago, Illinois, United States
- University of Illinois at Chicago, Department of Ophthalmology and Visual Sciences, Chicago, Illinois, United States
| |
Collapse
|
125
|
Ex Vivo Functional Evaluation of Synaptic Transmission from Rods to Rod Bipolar Cells in Mice. Methods Mol Biol 2018; 1753:203-216. [PMID: 29564791 DOI: 10.1007/978-1-4939-7720-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Mice have been widely used as a model organism to study mechanisms of phototransduction and synaptic transmission in the retina. Genetic manipulations and electrophysiological techniques for analysis of photoreceptor and rod bipolar cell function in mice are uniquely advanced. Here, we describe a set of biochemical and electrophysiological techniques for evaluation of synaptic transmission at the rod-rod bipolar cell synapse, which represents the first and key step in the processing of dim-light visual information.
Collapse
|
126
|
De novo transcriptomics reveal distinct phototransduction signaling components in the retina and skin of a color-changing vertebrate, the hogfish (Lachnolaimus maximus). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2018; 204:475-485. [PMID: 29492668 DOI: 10.1007/s00359-018-1254-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/22/2018] [Accepted: 02/22/2018] [Indexed: 10/17/2022]
Abstract
Across diverse taxa, an increasing number of photoreceptive systems are being discovered in tissues outside of the eye, such as in the skin. Dermal photoreception is believed to serve a variety of functions, including rapid color change via specialized cells called chromatophores. In vitro studies of this system among color-changing fish have suggested the use of a phototransduction signaling cascade that fundamentally differs from that of the retina. Thus, the goal of this study was to identify phototransduction genes and compare their expression in the retina and skin of a color-changing fish, the hogfish Lachnolaimus maximus. De novo transcriptomics revealed the expression of genes that may underlie distinct, yet complete phototransduction cascades in L. maximus retina and skin. In contrast to the five visual opsin genes and cGMP-dependent phototransduction components expressed in the retina of L. maximus, only a single short-wavelength sensitive opsin (SWS1) and putative cAMP-dependent phototransduction components were expressed in the skin. These data suggest a separate evolutionary history of phototransduction in the retina and skin of certain vertebrates and, for the first time, indicate an expression repertoire of genes that underlie a non-retinal phototransduction pathway in the skin of a color-changing fish.
Collapse
|
127
|
Lu Y, Liu C, Yao X. In vivo observation of transient photoreceptor movement correlated with oblique light stimulation. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2018; 10497:104971M. [PMID: 29950751 PMCID: PMC6016829 DOI: 10.1117/12.2287262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Rod-dominated transient retinal phototropism (TRP) has been observed in freshly isolated retinas, promising a noninvasive biomarker for high resolution assessment of retinal physiology. However, in vivo mapping of TRP is challenging due to its fast time course and sub-cellular signal magnitude. By developing a line-scanning and virtually structured detection based super-resolution ophthalmoscope, we report here in vivo observation of TRP in frog retina. In vivo characterization of TRP time course and magnitude were implemented by using variable light stimulus intensities.
Collapse
Affiliation(s)
- Yiming Lu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Changgeng Liu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
| |
Collapse
|
128
|
Field GD, Sampath AP. Behavioural and physiological limits to vision in mammals. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0072. [PMID: 28193817 DOI: 10.1098/rstb.2016.0072] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2016] [Indexed: 01/22/2023] Open
Abstract
Human vision is exquisitely sensitive-a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold.This article is part of the themed issue 'Vision in dim light'.
Collapse
Affiliation(s)
- Greg D Field
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Alapakkam P Sampath
- Stein Eye Institute, Department of Ophthalmology, UCLA, Los Angeles, CA 90095, USA
| |
Collapse
|
129
|
Cooper RF, Tuten WS, Dubra A, Brainard DH, Morgan JIW. Non-invasive assessment of human cone photoreceptor function. BIOMEDICAL OPTICS EXPRESS 2017; 8:5098-5112. [PMID: 29188106 PMCID: PMC5695956 DOI: 10.1364/boe.8.005098] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/04/2017] [Accepted: 10/08/2017] [Indexed: 05/18/2023]
Abstract
Vision begins when light isomerizes the photopigments within photoreceptors. Noninvasive cellular-scale observation of the structure of the human photoreceptor mosaic is made possible through the use of adaptive optics (AO) enhanced ophthalmoscopes, but establishing noninvasive objective measures of photoreceptor function on a similar scale has been more difficult. AO ophthalmoscope images acquired with near-infrared light show that individual cone photoreceptor reflectance can change in response to a visible stimulus. Here we show that the intrinsic response depends on stimulus wavelength and intensity, and that its action spectrum is well-matched to the spectral sensitivity of cone-mediated vision. Our results demonstrate that the cone reflectance response is mediated by photoisomerization, thus making it a direct measure of photoreceptor function.
Collapse
Affiliation(s)
- Robert F. Cooper
- Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
- Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - William S. Tuten
- Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
- Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Alfredo Dubra
- Ophthalmology, Stanford University, Stanford, CA, USA
| | | | - Jessica I. W. Morgan
- Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
- Center for Advanced Retinal and Ocular Therapeutics, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
130
|
Dephosphorylation by protein phosphatase 2A regulates visual pigment regeneration and the dark adaptation of mammalian photoreceptors. Proc Natl Acad Sci U S A 2017; 114:E9675-E9684. [PMID: 29078372 DOI: 10.1073/pnas.1712405114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Resetting of G-protein-coupled receptors (GPCRs) from their active state back to their biologically inert ground state is an integral part of GPCR signaling. This "on-off" GPCR cycle is regulated by reversible phosphorylation. Retinal rod and cone photoreceptors arguably represent the best-understood example of such GPCR signaling. Their visual pigments (opsins) are activated by light, transduce the signal, and are then inactivated by a GPCR kinase and arrestin. Although pigment inactivation by phosphorylation is well understood, the enzyme(s) responsible for pigment dephosphorylation and the functional significance of this reaction remain unknown. Here, we show that protein phosphatase 2A (PP2A) acts as opsin phosphatase in both rods and cones. Elimination of PP2A substantially slows pigment dephosphorylation, visual chromophore recycling, and ultimately photoreceptor dark adaptation. These findings demonstrate that visual pigment dephosphorylation regulates the dark adaptation of photoreceptors and provide insights into the role of this reaction in GPCR signaling.
Collapse
|
131
|
Gopalakrishna KN, Boyd K, Artemyev NO. Mechanisms of mutant PDE6 proteins underlying retinal diseases. Cell Signal 2017; 37:74-80. [PMID: 28583373 DOI: 10.1016/j.cellsig.2017.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 05/30/2017] [Accepted: 06/01/2017] [Indexed: 12/15/2022]
Abstract
Mutations in PDE6 genes encoding the effector enzymes in rods and cones underlie severe retinal diseases including retinitis pigmentosa (RP), autosomal dominant congenital stationary night blindness (adCSNB), and achromatopsia (ACHM). Here we examined a spectrum of pathogenic missense mutations in PDE6 using the system based on co-expression of cone PDE6C with its specialized chaperone AIPL1 and the regulatory Pγ subunit as a potent co-chaperone. We uncovered two mechanisms of PDE6C mutations underlying ACHM: (a) folding defects leading to expression of catalytically inactive proteins and (b) markedly diminished ability of Pγ to co-chaperone mutant PDE6C proteins thereby dramatically reducing the levels of functional enzyme. The mechanism of the Rambusch adCSNB associated with the H258N substitution in PDE6B was probed through the analysis of the model mutant PDE6C-H262N. We identified two interrelated deficits of PDE6C-H262N: disruption of the inhibitory interaction of Pγ with mutant PDE6C that markedly reduced the ability of Pγ to augment the enzyme folding. Thus, we conclude that the Rambusch adCSNB is triggered by low levels of the constitutively active PDE6. Finally, we examined PDE6C-L858V, which models PDE6B-L854V, an RP-linked mutation that alters the protein isoprenyl modification. This analysis suggests that the type of prenyl modifications does not impact the folding of PDE6, but it modulates the enzyme affinity for its trafficking partner PDE6D. Hence, the pathogenicity of PDE6B-L854V likely arises from its trafficking deficiency. Taken together, our results demonstrate the effectiveness of the PDE6C expression system to evaluate pathogenicity and elucidate the mechanisms of PDE6 mutations in retinal diseases.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Color Vision Defects/genetics
- Color Vision Defects/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 6/analysis
- Cyclic Nucleotide Phosphodiesterases, Type 6/genetics
- Cyclic Nucleotide Phosphodiesterases, Type 6/metabolism
- Eye Diseases, Hereditary/genetics
- Eye Diseases, Hereditary/metabolism
- Eye Proteins/analysis
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- HEK293 Cells
- Humans
- Mice
- Models, Molecular
- Mutation, Missense
- Myopia/genetics
- Myopia/metabolism
- Night Blindness/genetics
- Night Blindness/metabolism
- Protein Folding
- Protein Prenylation
- Retinal Diseases/genetics
- Retinal Diseases/metabolism
Collapse
Affiliation(s)
- Kota N Gopalakrishna
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, United States.
| |
Collapse
|
132
|
Ashur MM, Johnston NK, Dixson DL. Impacts of Ocean Acidification on Sensory Function in Marine Organisms. Integr Comp Biol 2017; 57:63-80. [DOI: 10.1093/icb/icx010] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
|
133
|
Peirson SN, Brown LA, Pothecary CA, Benson LA, Fisk AS. Light and the laboratory mouse. J Neurosci Methods 2017; 300:26-36. [PMID: 28414048 PMCID: PMC5909038 DOI: 10.1016/j.jneumeth.2017.04.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/10/2017] [Accepted: 04/11/2017] [Indexed: 02/06/2023]
Abstract
Light exerts widespread effects on physiology and behaviour. As well as the widely-appreciated role of light in vision, light also plays a critical role in many non-visual responses, including regulating circadian rhythms, sleep, pupil constriction, heart rate, hormone release and learning and memory. In mammals, responses to light are all mediated via retinal photoreceptors, including the classical rods and cones involved in vision as well as the recently identified melanopsin-expressing photoreceptive retinal ganglion cells (pRGCs). Understanding the effects of light on the laboratory mouse therefore depends upon an appreciation of the physiology of these retinal photoreceptors, including their differing sens itivities to absolute light levels and wavelengths. The signals from these photoreceptors are often integrated, with different responses involving distinct retinal projections, making generalisations challenging. Furthermore, many commonly used laboratory mouse strains carry mutations that affect visual or non-visual physiology, ranging from inherited retinal degeneration to genetic differences in sleep and circadian rhythms. Here we provide an overview of the visual and non-visual systems before discussing practical considerations for the use of light for researchers and animal facility staff working with laboratory mice.
Collapse
Affiliation(s)
- Stuart N Peirson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford Molecular Pathology Institute, Dunn School of Pathology, South Parks Road, Oxford, United Kingdom.
| | - Laurence A Brown
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford Molecular Pathology Institute, Dunn School of Pathology, South Parks Road, Oxford, United Kingdom
| | - Carina A Pothecary
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford Molecular Pathology Institute, Dunn School of Pathology, South Parks Road, Oxford, United Kingdom
| | - Lindsay A Benson
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford Molecular Pathology Institute, Dunn School of Pathology, South Parks Road, Oxford, United Kingdom
| | - Angus S Fisk
- Sleep and Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford Molecular Pathology Institute, Dunn School of Pathology, South Parks Road, Oxford, United Kingdom
| |
Collapse
|
134
|
Rose K, Walston ST, Chen J. Separation of photoreceptor cell compartments in mouse retina for protein analysis. Mol Neurodegener 2017; 12:28. [PMID: 28399904 PMCID: PMC5387348 DOI: 10.1186/s13024-017-0171-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/30/2017] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Light exposure triggers movement of certain signaling proteins within the cellular compartments of the highly polarized rod photoreceptor cell. This redistribution of proteins between the inner and outer segment compartments affects the performance and physiology of the rod cell. In addition, newly synthesized phototransduction proteins traverse from the site of their synthesis in the inner segment, through the thin connecting cilium, to reach their destination in the outer segment. Processes that impede normal trafficking of these abundant proteins lead to cell death. The study of movement and unique localization of biomolecules within the different compartments of the rod cell would be greatly facilitated by techniques that reliably separate these compartments. Ideally, these methods can be applied to the mouse retina due to the widespread usage of transgenic mouse models in the investigation of basic visual processes and disease mechanisms that affect vision. Although the retina is organized in distinct layers, the small and highly curved mouse retina makes physical separation of retinal layers a challenge. We introduce two peeling methods that efficiently and reliably isolate the rod outer segment and other cell compartments for Western blots to examine protein movement across these compartments. METHODS The first separation method employs Whatman® filter paper to successively remove the rod outer segments from isolated, live mouse retinas. The second method utilizes ScotchTM tape to peel the rod outer segment layer and the rod inner segment layer from lyophilized mouse retinas. Both procedures can be completed within one hour. RESULTS We utilize these two protocols on dark-adapted and light-exposed retinas of C57BL/6 mice and subject the isolated tissue layers to Western blots to demonstrate their effectiveness in detecting light-induced translocation of transducin (GNAT1) and rod arrestin (ARR1). Furthermore, we provide evidence that RGS9 does not undergo light-induced translocation. CONCLUSIONS These results demonstrate the effectiveness of the two different peeling protocols for the separation of the layered compartments of the mouse retina and their utility for investigations of protein compositions within these compartments.
Collapse
Affiliation(s)
- Kasey Rose
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Steven T Walston
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA. .,Department of Cell & Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
| |
Collapse
|
135
|
Pahlberg J, Frederiksen R, Pollock GE, Miyagishima KJ, Sampath AP, Cornwall MC. Voltage-sensitive conductances increase the sensitivity of rod photoresponses following pigment bleaching. J Physiol 2017; 595:3459-3469. [PMID: 28168711 DOI: 10.1113/jp273398] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/29/2017] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Following substantial bleaching of the visual pigment, the desensitization of the rod photovoltage is not as substantial as the desensitization of the rod outer segment photocurrent. The block of cation conductances during the internal dialysis of Cs+ further desensitizes the photovoltage thereby eliminating its difference in desensitization with the rod outer segment photocurrent. Bleached visual pigment produced an acceleration of the rod photovoltage with respect to the outer segment photocurrent, which is eliminated upon internal dialysis of Cs+ . ABSTRACT A majority of our visual experience occurs during the day when a substantial fraction of the visual pigment in our photoreceptor cells is bleached. Under these conditions it is widely believed that rods are saturated and do not contribute substantially to downstream signalling. However, behavioural experiments on subjects with only rod function reveals that these individuals unexpectedly retain substantial vision in daylight. We sought to understand this discrepancy by characterizing the sensitivity of rod photoresponses following exposure to bright bleaching light. Measurements of the rod outer segment photocurrent in transgenic mice, which have only rod function, revealed the well-studied reduction in the sensitivity of rod photoresponses following pigment bleaching. However, membrane voltage measurements showed that the desensitization of the photovoltage was considerably less than that of the outer segment photocurrent following equivalent pigment bleaching. This discrepancy was largely eliminated during the blockade of cation channels due to the internal dialysis of Cs+ , which increased the bleach-induced desensitization of the photovoltage and slowed its temporal characteristics. Thus, sensitization of the photovoltage by rod inner segment conductances appears to extend the operating range of rod phototransduction following pigment bleaching.
Collapse
Affiliation(s)
- Johan Pahlberg
- Ophthalmology, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Rikard Frederiksen
- Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Gabriel E Pollock
- Ophthalmology, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Kiyoharu J Miyagishima
- Unit on Retinal Neurophysiology, National Eye Institute Intramural Program, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alapakkam P Sampath
- Ophthalmology, Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - M Carter Cornwall
- Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118, USA
| |
Collapse
|
136
|
In vivo optophysiology reveals that G-protein activation triggers osmotic swelling and increased light scattering of rod photoreceptors. Proc Natl Acad Sci U S A 2017; 114:E2937-E2946. [PMID: 28320964 DOI: 10.1073/pnas.1620572114] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The light responses of rod and cone photoreceptors have been studied electrophysiologically for decades, largely with ex vivo approaches that disrupt the photoreceptors' subretinal microenvironment. Here we report the use of optical coherence tomography (OCT) to measure light-driven signals of rod photoreceptors in vivo. Visible light stimulation over a 200-fold intensity range caused correlated rod outer segment (OS) elongation and increased light scattering in wild-type mice, but not in mice lacking the rod G-protein alpha subunit, transducin (Gαt), revealing these responses to be triggered by phototransduction. For stimuli that photoactivated one rhodopsin per Gαt the rod OS swelling response reached a saturated elongation of 10.0 ± 2.1%, at a maximum rate of 0.11% s-1 Analyzing swelling as osmotically driven water influx, we find the H2O membrane permeability of the rod OS to be (2.6 ± 0.4) × 10-5 cm⋅s-1, comparable to that of other cells lacking aquaporin expression. Application of Van't Hoff's law reveals that complete activation of phototransduction generates a potentially harmful 20% increase in OS osmotic pressure. The increased backscattering from the base of the OS is explained by a model combining cytoplasmic swelling, translocation of dissociated G-protein subunits from the disc membranes into the cytoplasm, and a relatively higher H2O permeability of nascent discs in the basal rod OS. Translocation of phototransduction components out of the OS may protect rods from osmotic stress, which could be especially harmful in disease conditions that affect rod OS structural integrity.
Collapse
|
137
|
Abstract
Abstract
Vision begins in highly specialized light-sensing neurons, the rod and cone photoreceptors. Their task is to absorb photons, transduce the physical stimulus into neuronal signals, transmit the signals to the parallel signal processing pathways of the subsequent retinal network with the highest possible fidelity and continuously adapt to changes in stimulus intensities. If you imagine a pitch-black night with only a few photons hitting the retina and being absorbed by the photoreceptors and a bright sunny day with the photoreceptors being bombarded by billions of photons, you realize that a photoreceptor faces two fundamental challenges: it has to detect the light signal with the greatest sensitivity, e.g. a single photon leads to a change in the membrane potential of a rod photoreceptor and, at the same time, encode light intensities covering a broad dynamic range of several orders of magnitude. To fulfill these demands, photoreceptors have developed separate, structurally and functionally specialized compartments, which are the topic of this article: the outer segment for signal transduction and the terminal with its highly complex ribbon synapse for signal transmission.
Collapse
|
138
|
Zhang SN, Li XZ, Yang XY. Drug-likeness prediction of chemical constituents isolated from Chinese materia medica Ciwujia. JOURNAL OF ETHNOPHARMACOLOGY 2017; 198:131-138. [PMID: 28065780 DOI: 10.1016/j.jep.2017.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 12/10/2016] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Ciwujia (CWJ), one of the most commonly used Chinese materia medicas (CMMs), is derived from the roots, rhizomes, and stems of Acanthopanax senticosus harms (AS). CWJ has been used for the treatment of various central nervous system (CNS) and peripheral system diseases. Drug-likeness prediction can help to analyze the absorption, distribution, metabolism, and excretion (ADME) processes of the compounds in CWJ, as well as their potential therapeutic and toxic effects, which is of significance in the confirmation of the active material bases of CWJ. MATERIALS AND METHODS The ADME properties of the compounds were calculated through web based PreADMET program and ACD/I-Lab 2.0. The potential therapeutic and toxicity targets of these compounds were screened by the ChemQuery tool in DrugBank and T3DB. RESULTS 14/39 compounds had moderate or good oral bioavailability (OB). 29/39 compounds bound weakly to the plasma proteins. 18/39 compounds might pass across the blood-brain barrier (BBB). Most of these compounds showed low renal excretion ability. 25/39 compounds had 99 structurally similar drugs and 158 potential therapeutic targets. Additionally, 17/39 compounds had 53 structurally similar toxins and 126 potential toxicity targets. CONCLUSION Our study suggests that these compounds have a certain drug-likeness potentials, which are also likely to be the material bases of CWJ. These results may provide a reference for the safe use of CWJ and the expansion of its application scope.
Collapse
Affiliation(s)
- Shuai-Nan Zhang
- Department of Pharmacy, Guiyang University of Chinese Medicine, Guiyang 550025, PR China
| | - Xu-Zhao Li
- Department of Pharmacy, Guiyang University of Chinese Medicine, Guiyang 550025, PR China.
| | - Xu-Yan Yang
- First Affiliated Hospital, Heilongjiang University of Chinese Medicine, Harbin 150040, PR China.
| |
Collapse
|
139
|
C-terminal phosphorylation regulates the kinetics of a subset of melanopsin-mediated behaviors in mice. Proc Natl Acad Sci U S A 2017; 114:2741-2746. [PMID: 28223508 DOI: 10.1073/pnas.1611893114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and mediate several non-image-forming visual functions, including circadian photoentrainment and the pupillary light reflex (PLR). ipRGCs act as autonomous photoreceptors via the intrinsic melanopsin-based phototransduction pathway and as a relay for rod/cone input via synaptically driven responses. Under low light intensities, where only synaptically driven rod/cone input activates ipRGCs, the duration of the ipRGC response will be determined by the termination kinetics of the rod/cone circuits. Little is known, however, about the termination kinetics of the intrinsic melanopsin-based phototransduction pathway and its contribution to several melanopsin-mediated behaviors. Here, we show that C-terminal phosphorylation of melanopsin determines the recovery kinetics of the intrinsic melanopsin-based photoresponse in ipRGCs, the duration of the PLR, and the speed of reentrainment. In contrast, circadian phase alignment and direct effects of light on activity (masking) are not influenced by C-terminal phosphorylation of melanopsin. Electrophysiological measurements demonstrate that expression of a virally encoded melanopsin lacking all C-terminal phosphorylation sites (C terminus phosphonull) leads to a prolonged intrinsic light response. In addition, mice expressing the C terminus phosphonull in ipRGCs reentrain faster to a delayed light/dark cycle compared with mice expressing virally encoded WT melanopsin; however, the phase angle of entrainment and masking were indistinguishable. Importantly, a sustained PLR in the phosphonull animals is only observed at brighter light intensities that activate melanopsin phototransduction, but not at dimmer light intensities that activate only the rod/cone pathway. Taken together, our results highlight how the kinetics of the melanopsin photoresponse differentially regulate distinct light-mediated behaviors.
Collapse
|
140
|
Cerione RA. The experiences of a biochemist in the evolving world of G protein-dependent signaling. Cell Signal 2017; 41:2-8. [PMID: 28214588 DOI: 10.1016/j.cellsig.2017.02.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 02/14/2017] [Indexed: 12/24/2022]
Abstract
This review describes how a biochemist and basic researcher (i.e. myself) came to make a career in the area of receptor-coupled signal transduction and the roles cellular signaling activities play both in normal physiology and in disease. Much of what has been the best part of this research life is due to the time I spent with Bob Lefkowitz (1982-1985), during an extraordinary period in the emerging field of G-protein-coupled receptors. Among my laboratory colleagues were some truly outstanding scientists including Marc Caron, the late Jeffrey Stadel, Berta Strulovici, Jeff Benovic, Brian Kobilka, and Henrik Dohlman, as well as many more. I came to Bob's laboratory after being trained as a physical biochemist and enzymologist. Bob and his laboratory exposed me to a research style that made it possible to connect the kinds of fundamental biochemical and mechanistic questions that I loved to think about with a direct relevance to disease. Indeed, I owe Bob a great deal for having imparted a research style and philosophy that has remained with me throughout my career. Below, I describe how this has taken me on an interesting journey through various areas of cellular signaling, which have a direct relevance to the actions of one or another type of G-protein.
Collapse
Affiliation(s)
- Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853-6401, US.
| |
Collapse
|
141
|
Rainbow Enhancers Regulate Restrictive Transcription in Teleost Green, Red, and Blue Cones. J Neurosci 2017; 37:2834-2848. [PMID: 28193687 DOI: 10.1523/jneurosci.3421-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/31/2016] [Accepted: 01/27/2017] [Indexed: 01/24/2023] Open
Abstract
Photoreceptor-specific transcription of individual genes collectively constitutes the transcriptional profile that orchestrates the structural and functional characteristics of each photoreceptor type. It is challenging, however, to study the transcriptional specificity of individual photoreceptor genes because each gene's distinct spatiotemporal transcription patterns are determined by the unique interactions between a specific set of transcription factors and the gene's own cis-regulatory elements (CREs), which remain unknown for most of the genes. For example, it is unknown what CREs underlie the zebrafish mpp5bponli (ponli) and crumbs2b (crb2b) apical polarity genes' restrictive transcription in the red, green, and blue (RGB) cones in the retina, but not in other retinal cell types. Here we show that the intronic enhancers of both the ponli and crb2b genes are conserved among teleost species and that they share sequence motifs that are critical for RGB cone-specific transcription. Given their similarities in sequences and functions, we name the ponli and crb2b enhancers collectively rainbow enhancers. Rainbow enhancers may represent a cis-regulatory mechanism to turn on a group of genes that are commonly and restrictively expressed in RGB cones, which largely define the beginning of the color vision pathway.SIGNIFICANCE STATEMENT Dim-light achromatic vision and bright-light color vision are initiated in rod and several types of cone photoreceptors, respectively; these photoreceptors are structurally distinct from each other. In zebrafish, although quite different from rods and UV cones, RGB cones (red, green, and blue cones) are structurally similar and unite into mirror-symmetric pentamers (G-R-B-R-G) by adhesion. This structural commonality and unity suggest that a set of genes is commonly expressed only in RGB cones but not in other cells. Here, we report that the rainbow enhancers activate RGB cone-specific transcription of the ponli and crb2b genes. This study provides a starting point to study how RGB cone-specific transcription defines RGB cones' distinct functions for color vision.
Collapse
|
142
|
Combes RD, Shah AB. The use of in vivo, ex vivo, in vitro, computational models and volunteer studies in vision research and therapy, and their contribution to the Three Rs. Altern Lab Anim 2017; 44:187-238. [PMID: 27494623 DOI: 10.1177/026119291604400302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Much is known about mammalian vision, and considerable progress has been achieved in treating many vision disorders, especially those due to changes in the eye, by using various therapeutic methods, including stem cell and gene therapy. While cells and tissues from the main parts of the eye and the visual cortex (VC) can be maintained in culture, and many computer models exist, the current non-animal approaches are severely limiting in the study of visual perception and retinotopic imaging. Some of the early studies with cats and non-human primates (NHPs) are controversial for animal welfare reasons and are of questionable clinical relevance, particularly with respect to the treatment of amblyopia. More recently, the UK Home Office records have shown that attention is now more focused on rodents, especially the mouse. This is likely to be due to the perceived need for genetically-altered animals, rather than to knowledge of the similarities and differences of vision in cats, NHPs and rodents, and the fact that the same techniques can be used for all of the species. We discuss the advantages and limitations of animal and non-animal methods for vision research, and assess their relative contributions to basic knowledge and clinical practice, as well as outlining the opportunities they offer for implementing the principles of the Three Rs (Replacement, Reduction and Refinement).
Collapse
Affiliation(s)
| | - Atul B Shah
- Ophthalmic Surgeon, National Eye Registry Ltd, Leicester, UK
| |
Collapse
|
143
|
Petrukhin OV, Orlova TG, Nezvetsky AR, Orlov NY. The decrement in light sensitivity of the isolated frog retinal rod in the presence of a phosphorylation-resistant GDP analogue of guanosine-5′-O-(2-thiodiphosphate) as a confirmation of the hypothesis about transducin activation via the transphosphorylation mechanism. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916050249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
144
|
Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
Collapse
Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| |
Collapse
|
145
|
Petrukhin OV, Orlova TG, Nezvetsky AR, Orlov NY. Transducin-activated cGMP-specific phosphodiesterase of external segments of bovine retinal rods: The influence of magnesium ions. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916050237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
146
|
Petrukhin OV, Orlova TG, Nezvetsky AR, Orlov NY. Modeling of phototransduction processes in the photoreceptor disk membranes by the Monte Carlo method. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s000635091606021x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
147
|
Dizhoor AM, Olshevskaya EV, Peshenko IV. The R838S Mutation in Retinal Guanylyl Cyclase 1 (RetGC1) Alters Calcium Sensitivity of cGMP Synthesis in the Retina and Causes Blindness in Transgenic Mice. J Biol Chem 2016; 291:24504-24516. [PMID: 27703005 DOI: 10.1074/jbc.m116.755553] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/03/2016] [Indexed: 11/06/2022] Open
Abstract
Substitutions of Arg838 in the dimerization domain of a human retinal membrane guanylyl cyclase 1 (RetGC1) linked to autosomal dominant cone-rod degeneration type 6 (CORD6) change RetGC1 regulation in vitro by Ca2+ In addition, we find that R838S substitution makes RetGC1 less sensitive to inhibition by retinal degeneration-3 protein (RD3). We selectively expressed human R838S RetGC1 in mouse rods and documented the decline in rod vision and rod survival. To verify that changes in rods were specifically caused by the CORD6 mutation, we used for comparison cones, which in the same mice did not express R838S RetGC1 from the transgenic construct. The R838S RetGC1 expression in rod outer segments reduced inhibition of cGMP production in the transgenic mouse retinas at the free calcium concentrations typical for dark-adapted rods. The transgenic mice demonstrated early-onset and rapidly progressed with age decline in visual responses from the targeted rods, in contrast to the longer lasting preservation of function in the non-targeted cones. The decline in rod function in the retina resulted from a progressive degeneration of rods between 1 and 6 months of age, with the severity and pace of the degeneration consistent with the extent to which the Ca2+ sensitivity of the retinal cGMP production was affected. Our study presents a new experimental model for exploring cellular mechanisms of the CORD6-related photoreceptor death. This mouse model provides the first direct biochemical and physiological in vivo evidence for the Arg838 substitutions in RetGC1 being the culprit behind the pathogenesis of the CORD6 congenital blindness.
Collapse
Affiliation(s)
- Alexander M Dizhoor
- From the Department of Research, Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027.
| | - Elena V Olshevskaya
- From the Department of Research, Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Igor V Peshenko
- From the Department of Research, Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| |
Collapse
|
148
|
Sakurai K, Vinberg F, Wang T, Chen J, Kefalov VJ. The Na(+)/Ca(2+), K(+) exchanger 2 modulates mammalian cone phototransduction. Sci Rep 2016; 6:32521. [PMID: 27580676 PMCID: PMC5007492 DOI: 10.1038/srep32521] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/04/2016] [Indexed: 12/15/2022] Open
Abstract
Calcium ions (Ca2+) modulate the phototransduction cascade of vertebrate cone photoreceptors to tune gain, inactivation, and light adaptation. In darkness, the continuous current entering the cone outer segment through cGMP-gated (CNG) channels is carried in part by Ca2+, which is then extruded back to the extracellular space. The mechanism of Ca2+ extrusion from mammalian cones is not understood. The dominant view has been that the cone-specific isoform of the Na+/Ca2+, K+ exchanger, NCKX2, is responsible for removing Ca2+ from their outer segments. However, indirect evaluation of cone function in NCKX2-deficient (Nckx2−/−) mice by electroretinogram recordings revealed normal photopic b-wave responses. This unexpected result suggested that NCKX2 may not be involved in the Ca2+ homeostasis of mammalian cones. To address this controversy, we examined the expression of NCKX2 in mouse cones and performed transretinal recordings from Nckx2−/− mice to determine the effect of NCKX2 deletion on cone function directly. We found that Nckx2−/− cones exhibit compromised phototransduction inactivation, slower response recovery and delayed background adaptation. We conclude that NCKX2 is required for the maintenance of efficient Ca2+ extrusion from mouse cones. However, surprisingly, Nckx2−/− cones adapted normally in steady background light, indicating the existence of additional Ca2+-extruding mechanisms in mammalian cones.
Collapse
Affiliation(s)
- Keisuke Sakurai
- Department of Ophthalmology and Visual Sciences, Washington University, Saint Louis, MO 63110, USA
| | - Frans Vinberg
- Department of Ophthalmology and Visual Sciences, Washington University, Saint Louis, MO 63110, USA
| | - Tian Wang
- Zilkha Neurogenetic Institute, Department of Cell and Neurobiology &Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Department of Cell and Neurobiology &Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University, Saint Louis, MO 63110, USA
| |
Collapse
|
149
|
Bloch NI. The evolution of opsins and color vision: connecting genotype to a complex phenotype. ACTA BIOLÓGICA COLOMBIANA 2016. [DOI: 10.15446/abc.v21n3.53907] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Entender la base genética de los rasgos adaptativos es un paso crítico en el estudio de los procesos evolutivos. Para estudiar la conexión entre genotipo y fenotipo es importante definir el fenotipo a diferentes niveles: desde las proteínas que se construyen con base en un gen, hasta las características finales presentes en un organismo. Las opsinas y los fotopigmentos son elementos primordiales de la visión y entender cómo han evolucionado es fundamental en el estudio de la visión en los animales como un caracter derivado de selección natural o sexual. Este artículo se enfoca en este sistema, en el que se pueden conectar genotipo y fenotipo, como ejemplo de fenotipo complejo para ilustrar las dificultades de establecer una relación clara entre genotipo y fenotipo. Adicionalmente, este artículo tiene como objetivo discutir el funcionamiento del sistema de fotorrecepción, con énfasis particular en las aves, con el fin de enumerar varios factores que deben ser tenidos en cuenta para predecir cambios en la visión a partir del estudio de los fotopigmentos. Dado que los modelos basados en la visión de aves son cada vez más usados en diversas áreas de la biología evolutiva tales como: selección de pareja, depredación y camuflaje; se hace relevante entender los fundamentos y limitaciones de estos modelos. Por esta razón, en este artículo discuto los detalles y aspectos prácticos del uso de los modelos de visión existentes para aves, con el fin de facilitar su uso en futuras investigaciones en diversas áreas de evolución.
Collapse
|
150
|
Sonoda T, Schmidt TM. Re-evaluating the Role of Intrinsically Photosensitive Retinal Ganglion Cells: New Roles in Image-Forming Functions. Integr Comp Biol 2016; 56:834-841. [DOI: 10.1093/icb/icw066] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|