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Hanke-Gogokhia C, Zapadka TE, Finkelstein S, Klingeborn M, Maugel TK, Singer JH, Arshavsky VY, Demb JB. The Structural and Functional Integrity of Rod Photoreceptor Ribbon Synapses Depends on Redundant Actions of Dynamins 1 and 3. J Neurosci 2024; 44:e1379232024. [PMID: 38641407 PMCID: PMC11209669 DOI: 10.1523/jneurosci.1379-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 04/02/2024] [Accepted: 04/13/2024] [Indexed: 04/21/2024] Open
Abstract
Vertebrate vision begins with light absorption by rod and cone photoreceptors, which transmit signals from their synaptic terminals to second-order neurons: bipolar and horizontal cells. In mouse rods, there is a single presynaptic ribbon-type active zone at which the release of glutamate occurs tonically in the dark. This tonic glutamatergic signaling requires continuous exo- and endocytosis of synaptic vesicles. At conventional synapses, endocytosis commonly requires dynamins: GTPases encoded by three genes (Dnm1-3), which perform membrane scission. Disrupting endocytosis by dynamin deletions impairs transmission at conventional synapses, but the impact of disrupting endocytosis and the role(s) of specific dynamin isoforms at rod ribbon synapses are understood incompletely. Here, we used cell-specific knock-outs (KOs) of the neuron-specific Dnm1 and Dnm3 to investigate the functional roles of dynamin isoforms in rod photoreceptors in mice of either sex. Analysis of synaptic protein expression, synapse ultrastructure, and retinal function via electroretinograms (ERGs) showed that dynamins 1 and 3 act redundantly and are essential for supporting the structural and functional integrity of rod ribbon synapses. Single Dnm3 KO showed no phenotype, and single Dnm1 KO only modestly reduced synaptic vesicle density without affecting vesicle size and overall synapse integrity, whereas double Dnm1/Dnm3 KO impaired vesicle endocytosis profoundly, causing enlarged vesicles, reduced vesicle density, reduced ERG responses, synaptic terminal degeneration, and disassembly and degeneration of postsynaptic processes. Concurrently, cone function remained intact. These results show the fundamental redundancy of dynamins 1 and 3 in regulating the structure and function of rod ribbon synapses.
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Affiliation(s)
- Christin Hanke-Gogokhia
- Departments of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut 06511
| | - Thomas E Zapadka
- Departments of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut 06511
- Cellular & Molecular Physiology, Yale University, New Haven, Connecticut 06511
| | - Stella Finkelstein
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27705
| | - Mikael Klingeborn
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27705
| | - Timothy K Maugel
- Department of Biology, University of Maryland, College Park, Maryland 20742
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, Maryland 20742
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27705
| | - Jonathan B Demb
- Departments of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut 06511
- Cellular & Molecular Physiology, Yale University, New Haven, Connecticut 06511
- Department of Neuroscience, Yale University, New Haven, Connecticut 06511
- Wu Tsai Institute, Yale University, New Haven, Connecticut 06511
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Wu Y, Zheng X, Ding Y, Zhou M, Wei Z, Liu T, Liao K. The molecular chaperone Hsp90α deficiency causes retinal degeneration by disrupting Golgi organization and vesicle transportation in photoreceptors. J Mol Cell Biol 2021; 12:216-229. [PMID: 31408169 PMCID: PMC7181719 DOI: 10.1093/jmcb/mjz048] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 03/01/2019] [Accepted: 04/28/2019] [Indexed: 11/14/2022] Open
Abstract
Heat shock protein 90 (Hsp90) is an abundant molecular chaperone with two isoforms, Hsp90α and Hsp90β. Hsp90β deficiency causes embryonic lethality, whereas Hsp90α deficiency causes few abnormities except male sterility. In this paper, we reported that Hsp90α was exclusively expressed in the retina, testis, and brain. Its deficiency caused retinitis pigmentosa (RP), a disease leading to blindness. In Hsp90α-deficient mice, the retina was deteriorated and the outer segment of photoreceptor was deformed. Immunofluorescence staining and electron microscopic analysis revealed disintegrated Golgi and aberrant intersegmental vesicle transportation in Hsp90α-deficient photoreceptors. Proteomic analysis identified microtubule-associated protein 1B (MAP1B) as an Hsp90α-associated protein in photoreceptors. Hspα deficiency increased degradation of MAP1B by inducing its ubiquitination, causing α-tubulin deacetylation and microtubule destabilization. Furthermore, the treatment of wild-type mice with 17-DMAG, an Hsp90 inhibitor of geldanamycin derivative, induced the same retinal degeneration as Hsp90α deficiency. Taken together, the microtubule destabilization could be the underlying reason for Hsp90α deficiency-induced RP.
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Affiliation(s)
- Yuan Wu
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiudan Zheng
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Yubo Ding
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Min Zhou
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Zhuang Wei
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Tao Liu
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Kan Liao
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
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Park JS, Kim JI, Lim HJ, Ryu SK, Kwon E, Han KM, Nam KT, Lee HW, Kang BC. Differential manifestation of ocular phenotypes in TALEN-mediated p19 arf knockout FVB/N and C57BL/6J mouse lines. Genes Genomics 2020; 42:1023-1033. [PMID: 32712838 DOI: 10.1007/s13258-020-00959-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/09/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND p19arf, primarily known as a tumor suppressor, has also been reported to play an essential role in normal development of mouse eyes. Consistently, lack of p19arf has been associated with ocular defects, but the mixed background of the knockout (KO) mouse strain used raised a concern on the accuracy of the phenotypes observed in association with the targeted gene due to genetic heterogeneity. OBJECT We carried out a study to investigate into the effect of genetic background on the manifestation of p19arf KO associated phenotypes. METHODS We characterized the phenotypes of novel p19arf KO mouse lines generated in FVB/N and C57BL/6J using a transcription activator-like effector nuclease (TALEN) system in comparison to the reported phenotypes of three other p19arf-deficient mouse lines generated using homologous recombination. RESULTS Ninety-five percent of FVB/N-p19arf KO mice showed ocular opacity from week 4 after birth which worsened rapidly until week 6, while such abnormality was absent in C57BL/6J-p19arf KO mice up to the age of 26 weeks. Histopathological analysis revealed retrolental masses and dysplasia in the retinal layer in FVB/N-p19arf KO mice from week 4. Besides these, both strains developed normally from birth to week 26 without increased tumorigenesis except for a subcutaneous tumor found in a C57BL/6J-p19arf KO mouse. CONCLUSION Our findings demonstrated surprisingly variable manifestation of p19arf-linked phenotypes between FVB/N and C57BL/6J mice, and furthermore between our mouse lines and the established lines, indicating a critical impact of genetic background on functional study of genes using gene targeting strategies in mice.
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Affiliation(s)
- Jin-Sung Park
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Joo-Il Kim
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyun-Jin Lim
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Soo-Kyung Ryu
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Euna Kwon
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Kang-Min Han
- Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Pathology, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - Ki-Taek Nam
- College of Medicine Severance Biomedical Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Han-Woong Lee
- Department of Biochemistry, Yonsei University, Seoul, Republic of Korea
| | - Byeong-Cheol Kang
- Department of Experimental Animal Research, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea. .,Graduate School of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. .,Biomedical Center for Animal Resource and Development, Seoul National University College of Medicine, Seoul, Republic of Korea. .,Designed Animal Resource Center, Institute of GreenBio Science and Technology, Seoul National University, Pyeongchang-gun, Gangwon-do, Republic of Korea.
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Sex-related differences in the progressive retinal degeneration of the rd10 mouse. Exp Eye Res 2019; 187:107773. [PMID: 31445902 DOI: 10.1016/j.exer.2019.107773] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/21/2019] [Accepted: 08/21/2019] [Indexed: 01/30/2023]
Abstract
The retinal degeneration 10 (rd10) mouse is a model of autosomal recessive retinitis pigmentosa (RP), a disease that causes blindness through the progressive loss of photoreceptors. This study shows evidence of sex-related differences in RP onset and progression in rd10 retinas. The disease onset was considerably earlier in the female rd10 mice than in the male rd10 mice, as evidenced by a loss of PDE6β proteins and rod-dominated electroretinogram (ERG) responses at an early age. Single photopic flash and flicker ERG responses and immunolabeling of opsin molecules were analyzed in both genders to assess the sex differences in the degeneration of cones in the RP retinas. The averaged amplitudes of cone-mediated ERG responses obtained from the females were significantly smaller than the amplitudes of the responses from the age-matched males in the late stages of the RP, suggesting that cones might degenerate faster in the female retinas as the disease progressed. The rapid degeneration of cones caused a more substantial decrease in the ERG responses derived from the On-pathway than the Off-pathway in the females. In addition, the male rd10 mice had heavier body weights than their female counterparts aged between postnatal (P)18 and P50 days. In summary, female rd10 mice were more susceptible to retinal degeneration, suggesting that the female sex might be a risk factor for RP. The results have important implications for future studies exploring potential sex-related differences in RP development and progression in the clinic.
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Ji YD, Luo ZL, Chen CX, Li B, Gong J, Wang YX, Chen L, Yao SL, Shang Y. BML-111 suppresses TGF-β1-induced lung fibroblast activation in vitro and decreases experimental pulmonary fibrosis in vivo. Int J Mol Med 2018; 42:3083-3092. [PMID: 30280199 PMCID: PMC6202103 DOI: 10.3892/ijmm.2018.3914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 09/04/2018] [Indexed: 01/07/2023] Open
Abstract
Pulmonary fibrosis is an aggressive end‑stage disease. Transforming growth factor‑β1 (TGF‑β1) mediates lung fibroblast activation and is essential for the progress of pulmonary fibrosis. BML‑111, a lipoxinA4 (LXA4) receptor (ALX) agonist, has been reported to possess anti‑fibrotic properties. The present study aimed to elucidate whether BML‑111 inhibits TGF‑β1‑induced mouse embryo lung fibroblast (NIH3T3 cell line) activation in vitro and bleomycin (BLM)‑induced pulmonary fibrosis in vivo. In vitro experiments demonstrated that BML‑111 treatment inhibits TGF‑β1‑induced NIH3T3 cell viability and the expression of smooth muscle α actin (α‑SMA), fibronectin and total collagen. Furthermore, this suppressive effect was associated with mothers against decapentaplegic homolog (Smad)2/3, extracellular signal‑regulated kinase (ERK) and Akt phosphorylation interference. In vivo experiments revealed that BML‑111 treatment markedly improved survival rate and ameliorated the destruction of lung tissue structure. It also reduced interleukin‑1β (IL‑1β), tumor necrosis factor‑α (TNF‑α) and TGF‑β1 expression in the BLM intratracheal mouse model. In addition, the expression ofα‑SMA and extracellular matrix (ECM) deposition (total collagen, hydroxyproline and fibronectin) were also suppressed following BML‑111 treatment. However, BOC‑2, an antagonist of ALX, partially weakened the effects of BML‑111. In conclusion, these results indicated that BML‑111 inhibits TGF‑β1‑induced fibroblasts activation and alleviates BLM‑induced pulmonary fibrosis. Therefore, BML‑111 may be used as a potential therapeutic agent for pulmonary fibrosis treatment.
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Affiliation(s)
- Yu-Dong Ji
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Zhen-Long Luo
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Chun-Xiu Chen
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Bo Li
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Jie Gong
- Department of Critical Care Medicine, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Ya-Xin Wang
- Department of Critical Care Medicine, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Lin Chen
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Shang-Long Yao
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - You Shang
- Department of Critical Care Medicine, Institute of Anesthesiology and Critical Care, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
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Hanna J, Yücel YH, Zhou X, Mathieu E, Paczka-Giorgi LA, Gupta N. Progressive loss of retinal blood vessels in a live model of retinitis pigmentosa. CANADIAN JOURNAL OF OPHTHALMOLOGY 2017; 53:391-401. [PMID: 30119795 DOI: 10.1016/j.jcjo.2017.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess retinal blood vessels in a live retinitis pigmentosa (RP) model with rd1 mutation and green fluorescent protein (GFP) expressed in vascular endothelium. METHODS Homozygous (hm) Tie2-GFP mice with rd1 mutation and known retinal degeneration were crossed with wild-type CD1 mice to generate control heterozygous (ht) Tie2-GFP mice. The retinas of 16 live hm mice were evaluated at 2 weeks and 3, 5, and 8 months of age, and compared with age-matched control ht and CD1 mice by optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy (cSLO). Fluorescence intensity was measured and compared between strains at 3, 5, and 8 months. In vivo findings were validated by immunostaining with collagen IV and isolectin histopathology. RESULTS All hm Tie2-GFP mice showed progressive outer retinal degeneration by OCT. Loss of small branches of blood vessels and then larger main vessels was seen by cSLO. Retinal tissue and vessels were preserved in control ht mice. At all ages, measurements of fluorescence intensity were reduced in hm compared with ht mice (p < 0.001). In all strains, intensity at 8 months was reduced compared with 3 months (p < 0.001) and 5 months (p = 0.021). Histopathological studies confirmed in vivo findings and revealed a pattern of blood vessel regression in the deep plexus, followed by intermediate and superficial retinal plexuses. CONCLUSIONS This is the first evidence of progressive loss of retinal blood vessels in a live mouse model of RP. These findings may be highly relevant to understanding retinal degeneration in RP to prevent blindness.
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Affiliation(s)
- Joseph Hanna
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont; Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ont
| | - Yeni H Yücel
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont; Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ont; Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Toronto, Ont; Ophthalmic Pathology Laboratory, University of Toronto, Toronto, Ont
| | - Xun Zhou
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont
| | - Emily Mathieu
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont; Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ont
| | - Luz A Paczka-Giorgi
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont
| | - Neeru Gupta
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ont; Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ont; Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, Toronto, Ont; Dalla Lana School of Public Health, University of Toronto, Toronto, Ont.
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Asthana A, Baksi S, Ashok A, Karmakar S, Mammadova N, Kokemuller R, Greenlee MH, Kong Q, Singh N. Prion protein facilitates retinal iron uptake and is cleaved at the β-site: Implications for retinal iron homeostasis in prion disorders. Sci Rep 2017; 7:9600. [PMID: 28851903 PMCID: PMC5575325 DOI: 10.1038/s41598-017-08821-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/17/2017] [Indexed: 12/22/2022] Open
Abstract
Prion disease-associated retinal degeneration is attributed to PrP-scrapie (PrPSc), a misfolded isoform of prion protein (PrPC) that accumulates in the neuroretina. However, a lack of temporal and spatial correlation between PrPSc and cytotoxicity suggests the contribution of host factors. We report retinal iron dyshomeostasis as one such factor. PrPC is expressed on the basolateral membrane of retinal-pigment-epithelial (RPE) cells, where it mediates uptake of iron by the neuroretina. Accordingly, the neuroretina of PrP-knock-out mice is iron-deficient. In RPE19 cells, silencing of PrPC decreases ferritin while over-expression upregulates ferritin and divalent-metal-transporter-1 (DMT-1), indicating PrPC-mediated iron uptake through DMT-1. Polarization of RPE19 cells results in upregulation of ferritin by ~10-fold and β-cleavage of PrPC, the latter likely to block further uptake of iron due to cleavage of the ferrireductase domain. A similar β-cleavage of PrPC is observed in mouse retinal lysates. Scrapie infection causes PrPSc accumulation and microglial activation, and surprisingly, upregulation of transferrin despite increased levels of ferritin. Notably, detergent-insoluble ferritin accumulates in RPE cells and correlates temporally with microglial activation, not PrPSc accumulation, suggesting that impaired uptake of iron by PrPSc combined with inflammation results in retinal iron-dyshomeostasis, a potentially toxic host response contributing to prion disease-associated pathology.
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Affiliation(s)
- Abhishek Asthana
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Shounak Baksi
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Ajay Ashok
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Shilpita Karmakar
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Najiba Mammadova
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Robyn Kokemuller
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Mary Heather Greenlee
- Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, Iowa, 50010, USA
| | - Qingzhong Kong
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA
| | - Neena Singh
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, 44106, USA.
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Rodgers HM, Belcastro M, Sokolov M, Mathers PH. Embryonic markers of cone differentiation. Mol Vis 2016; 22:1455-1467. [PMID: 28031694 PMCID: PMC5178185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 12/20/2016] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Photoreceptor cells are born in two distinct phases of vertebrate retinogenesis. In the mouse retina, cones are born primarily during embryogenesis, while rod formation occurs later in embryogenesis and early postnatal ages. Despite this dichotomy in photoreceptor birthdates, the visual pigments and phototransduction machinery are not reactive to visual stimulus in either type of photoreceptor cell until the second postnatal week. Several markers of early cone formation have been identified, including Otx2, Crx, Blimp1, NeuroD, Trβ2, Rorβ, and Rxrγ, and all are thought to be involved in cellular determination. However, little is known about the expression of proteins involved in cone visual transduction during early retinogenesis. Therefore, we sought to characterize visual transduction proteins that are expressed specifically in photoreceptors during mouse embryogenesis. METHODS Eye tissue was collected from control and phosducin-null mice at embryonic and early postnatal ages. Immunohistochemistry and quantitative reverse transcriptase-PCR (qPCR) were used to measure the spatial and temporal expression patterns of phosducin (Pdc) and cone transducin γ (Gngt2) proteins and transcripts in the embryonic and early postnatal mouse retina. RESULTS We identified the embryonic expression of phosducin (Pdc) and cone transducin γ (Gngt2) that coincides temporally and spatially with the earliest stages of cone histogenesis. Using immunohistochemistry, the phosducin protein was first detected in the retina at embryonic day (E)12.5, and cone transducin γ was observed at E13.5. The phosducin and cone transducin γ proteins were seen only in the outer neuroblastic layer, consistent with their expression in photoreceptors. At the embryonic ages, phosducin was coexpressed with Rxrγ, a known cone marker, and with Otx2, a marker of photoreceptors. Pdc and Gngt2 mRNAs were detected as early as E10.5 with qPCR, although at low levels. CONCLUSIONS Visual transduction proteins are expressed at the earliest stages in developing cones, well before the onset of opsin gene expression. Given the delay in opsin expression in rods and cones, we speculate on the embryonic function of these G-protein signaling components beyond their roles in the visual transduction cascade.
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Affiliation(s)
- Helen M. Rodgers
- Sensory Neuroscience Research Center, West Virginia University School of Medicine, Morgantown, WV,Neuroscience Graduate Program, West Virginia University School of Medicine, Morgantown, WV,Department of Otolaryngology, West Virginia University School of Medicine, Morgantown, WV
| | - Marycharmain Belcastro
- Sensory Neuroscience Research Center, West Virginia University School of Medicine, Morgantown, WV,Department of Ophthalmology, West Virginia University School of Medicine, Morgantown, WV
| | - Maxim Sokolov
- Sensory Neuroscience Research Center, West Virginia University School of Medicine, Morgantown, WV,Department of Ophthalmology, West Virginia University School of Medicine, Morgantown, WV,Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV
| | - Peter H. Mathers
- Sensory Neuroscience Research Center, West Virginia University School of Medicine, Morgantown, WV,Department of Otolaryngology, West Virginia University School of Medicine, Morgantown, WV,Department of Ophthalmology, West Virginia University School of Medicine, Morgantown, WV,Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV
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