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Bao N, Wang J, Yue Q, Cao F, Gu X, Wen K, Kong W, Gu M. Chrysophanol-mediated trx-1 activation attenuates renal fibrosis through inhibition of the JNK/Cx43 signaling pathway. Ren Fail 2024; 46:2398710. [PMID: 39238246 PMCID: PMC11382722 DOI: 10.1080/0886022x.2024.2398710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 08/07/2024] [Accepted: 08/26/2024] [Indexed: 09/07/2024] Open
Abstract
PURPOSE This study aimed to investigate the inhibitory effect of chrysophanol on renal fibrosis and its molecular mechanism. METHODS Initially, potential targets of chrysophanol were predicted through network pharmacology analysis, and a protein-protein interaction network of these targets was constructed using Venn diagrams and the STRING database. GO enrichment analysis predicted the biological process of chrysophanol in treating renal fibrosis. Subsequently, both in vivo and in vitro experiments were conducted using unilateral ureteral obstruction (UUO) induced CKD mouse model and HK-2 cell model, respectively. In the mouse model, different doses of chrysophanol were administered to assess its renal protective effects through biochemical indicators, histological examination, and immunofluorescence staining. In the cell model, the regulatory effect of chrysophanol on the Trx-1/JNK/Cx43 pathway was evaluated using western blotting and flow cytometry. RESULTS Chrysophanol treatment significantly ameliorated renal dysfunction and histopathological damage in the UUO mouse model, accompanied by a reduction in serum oxidative stress markers. Furthermore, chrysophanol markedly upregulated the expression of Trx-1 in renal tissues and inhibited the activation of the JNK/Cx43 signaling pathway. At the cellular level, chrysophanol enhanced the activity of Trx-1 and downregulated the JNK/Cx43 signaling pathway, thereby inhibiting TGF-β induced oxidative stress and cell apoptosis. CONCLUSION This study demonstrated a significant inhibitory effect of chrysophanol on renal fibrosis, mediated by the activation of Trx-1 to inhibit the JNK/Cx43 pathway. These findings provide experimental support for the potential use of chrysophanol as a therapeutic agent for renal fibrosis.
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Affiliation(s)
- Neng Bao
- Department of Nephrology, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Nanjing city, Jiangsu, China
| | - Jin Wang
- Department of Gastroenterology, Affiliated Hospital of Jiangnan University, Jiangsu, China
| | - Qiyu Yue
- School of Chinese Medicine & School of Integrated Chinese and Western Medicine, Nanjing University of Chinese Medicine, Jiangsu, China
| | - Fang Cao
- Department of Nephrology, Changshu Hospital affiliated to Nanjing University of Chinese Medicine, Changshu city, Jiangsu, China
| | - Xuejing Gu
- Department of Nephrology, Changshu Hospital affiliated to Nanjing University of Chinese Medicine, Changshu city, Jiangsu, China
| | - Kejian Wen
- Department of Nephrology, Changshu Hospital affiliated to Nanjing University of Chinese Medicine, Changshu city, Jiangsu, China
| | - Wei Kong
- Department of Nephrology, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Nanjing city, Jiangsu, China
| | - Mingjia Gu
- Department of Nephrology, Changshu Hospital affiliated to Nanjing University of Chinese Medicine, Changshu city, Jiangsu, China
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2
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Ramsay E, Lajunen T, Bhattacharya M, Reinisalo M, Rilla K, Kidron H, Terasaki T, Urtti A. Selective drug delivery to the retinal cells: Biological barriers and avenues. J Control Release 2023; 361:1-19. [PMID: 37481214 DOI: 10.1016/j.jconrel.2023.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 06/09/2023] [Accepted: 07/16/2023] [Indexed: 07/24/2023]
Abstract
Retinal drug delivery is a challenging, but important task, because most retinal diseases are still without any proper therapy. Drug delivery to the retina is hampered by the anatomical and physiological barriers resulting in minimal bioavailability after topical ocular and systemic administrations. Intravitreal injections are current method-of-choice in retinal delivery, but these injections show short duration of action for small molecules and low target bioavailability for many protein, gene based drugs and nanomedicines. State-of-art delivery systems are based on prolonged retention, controlled drug release and physical features (e.g. size and charge). However, drug delivery to the retina is not cell-specific and these approaches do not facilitate intracellular delivery of modern biological drugs (e.g. intracellular proteins, RNA based medicines, gene editing). In this focused review we highlight biological factors and mechanisms that form the basis for the selective retinal drug delivery systems in the future. Therefore, we are presenting current knowledge related to retinal membrane transporters, receptors and targeting ligands in relation to nanomedicines, conjugates, extracellular vesicles, and melanin binding. These issues are discussed in the light of retinal structure and cell types as well as future prospects in the field. Unlike in some other fields of targeted drug delivery (e.g. cancer research), selective delivery technologies have been rarely studied, even though cell targeted delivery may be even more feasible after local administration into the eye.
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Affiliation(s)
- Eva Ramsay
- Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 University of Helsinki, Finland
| | - Tatu Lajunen
- Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 University of Helsinki, Finland; School of Pharmacy, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland
| | - Madhushree Bhattacharya
- Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 University of Helsinki, Finland
| | - Mika Reinisalo
- School of Pharmacy, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland
| | - Kirsi Rilla
- School of Medicine, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland
| | - Heidi Kidron
- Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 University of Helsinki, Finland
| | - Tetsuya Terasaki
- School of Pharmacy, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland
| | - Arto Urtti
- Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 University of Helsinki, Finland; School of Pharmacy, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland.
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3
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Hilgen G. Connexin45 colocalization patterns in the plexiform layers of the developing mouse retina. J Anat 2023; 243:258-264. [PMID: 35315057 PMCID: PMC10335376 DOI: 10.1111/joa.13651] [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: 01/13/2022] [Revised: 02/14/2022] [Accepted: 02/28/2022] [Indexed: 11/29/2022] Open
Abstract
Chemical and electrical synapses (gap junctions) are widely prevalent in the nervous system. Gap junctions emerge long before chemical synapses, allowing communication between developing cells, and are thought to be involved in establishing neural circuits. Mounting evidence indicates that these two modalities of synaptic transmission closely interact during retinal development and that such interactions play a critical role in synaptogenesis and circuit formation during the perinatal period. In vertebrates, gap junctions consist of two connexins which in turn are made up of six connexins (Cx). To what extent Cx45 and Cx36, the most abundant connexins in the retina, are involved in synaptogenesis and retinal circuit formation is not known. The here presented immunohistochemical study used stainings of Cx45, Cx36 and Synaptophysin in the outer and inner (IPL) plexiform layers of postnatal day 8-16 mice retinas to shed light on the role of connexins during critical neuronal developmental processes. Cx45 and Cx36 expressions in both plexiform layers of the mouse retina increased till eye opening and dropped afterwards. The percentage of heterotypic Cx45/Cx36 gap junctions is also higher before the critical event of eye opening. Finally, Cx45 is closely located and/or colocalized with Synaptophysin also shortly before eye opening in the IPL of the mouse retina. All findings point towards a pivotal role for Cx45 during postnatal synaptogenesis in the mouse retina. However, a more functional study is needed to determine the role of Cx45 during synaptogenesis and circuit formation.
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Affiliation(s)
- Gerrit Hilgen
- Health & Life Sciences, Applied SciencesNorthumbria UniversityNewcastle upon TyneUK
- Biosciences InstituteNewcastle UniversityNewcastle upon TyneUK
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4
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Móvio MI, de Lima-Vasconcellos TH, Dos Santos GB, Echeverry MB, Colombo E, Mattos LS, Resende RR, Kihara AH. Retinal organoids from human-induced pluripotent stem cells: From studying retinal dystrophies to early diagnosis of Alzheimer's and Parkinson's disease. Semin Cell Dev Biol 2023; 144:77-86. [PMID: 36210260 DOI: 10.1016/j.semcdb.2022.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 09/15/2022] [Accepted: 09/17/2022] [Indexed: 11/18/2022]
Abstract
Human-induced pluripotent stem cells (hiPSCs) have provided new methods to study neurodegenerative diseases. In addition to their wide application in neuronal disorders, hiPSCs technology can also encompass specific conditions, such as inherited retinal dystrophies. The possibility of evaluating alterations related to retinal disorders in 3D organoids increases the truthfulness of in vitro models. Moreover, both Alzheimer's (AD) and Parkinson's disease (PD) have been described as causing early retinal alterations, generating beta-amyloid protein accumulation, or affecting dopaminergic amacrine cells. This review addresses recent advances and future perspectives obtained from in vitro modeling of retinal diseases, focusing on retinitis pigmentosa (RP). Additionally, we depicted the possibility of evaluating changes related to AD and PD in retinal organoids obtained from potential patients long before the onset of the disease, constituting a valuable tool in early diagnosis. With this, we pointed out prospects in the study of retinal dystrophies and early diagnosis of AD and PD.
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Affiliation(s)
- Marília Inês Móvio
- Laboratório de Neurogenética, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
| | | | | | - Marcela Bermudez Echeverry
- Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
| | - Elisabetta Colombo
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Leonardo S Mattos
- Biomedical Robotics Laboratory, Department of Advanced Robotics, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Rodrigo Ribeiro Resende
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Alexandre Hiroaki Kihara
- Laboratório de Neurogenética, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil; Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil.
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5
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Kovács-Öller T, Szarka G, Hoffmann G, Péntek L, Valentin G, Ross L, Völgyi B. Extrinsic and Intrinsic Factors Determine Expression Levels of Gap Junction-Forming Connexins in the Mammalian Retina. Biomolecules 2023; 13:1119. [PMID: 37509155 PMCID: PMC10377540 DOI: 10.3390/biom13071119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Gap junctions (GJs) are not static bridges; instead, GJs as well as the molecular building block connexin (Cx) proteins undergo major expression changes in the degenerating retinal tissue. Various progressive diseases, including retinitis pigmentosa, glaucoma, age-related retinal degeneration, etc., affect neurons of the retina and thus their neuronal connections endure irreversible changes as well. Although Cx expression changes might be the hallmarks of tissue deterioration, GJs are not static bridges and as such they undergo adaptive changes even in healthy tissue to respond to the ever-changing environment. It is, therefore, imperative to determine these latter adaptive changes in GJ functionality as well as in their morphology and Cx makeup to identify and distinguish them from alterations following tissue deterioration. In this review, we summarize GJ alterations that take place in healthy retinal tissue and occur on three different time scales: throughout the entire lifespan, during daily changes and as a result of quick changes of light adaptation.
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Affiliation(s)
- Tamás Kovács-Öller
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Gergely Szarka
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Gyula Hoffmann
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
| | - Loretta Péntek
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Gréta Valentin
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
| | - Liliana Ross
- Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Béla Völgyi
- Szentágothai Research Centre, University of Pécs, 7624 Pécs, Hungary
- Department of Neurobiology, University of Pécs, 7624 Pécs, Hungary
- NEURON-066 Rethealthsi Research Group, 7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, 7624 Pécs, Hungary
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6
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Maruyama T, Ishii T, Kaneda M. Starburst amacrine cells form gap junctions in the early postnatal stage of the mouse retina. Front Cell Neurosci 2023; 17:1173579. [PMID: 37293630 PMCID: PMC10244514 DOI: 10.3389/fncel.2023.1173579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/03/2023] [Indexed: 06/10/2023] Open
Abstract
Although gap junctional coupling in the developing retina is important for the maturation of neuronal networks, its role in the development of individual neurons remains unclear. Therefore, we herein investigated whether gap junctional coupling by starburst amacrine cells (SACs), a key neuron for the formation of direction selectivity, occurs during the developmental stage in the mouse retina. Neurobiotin-injected SACs coupled with many neighboring cells before eye-opening. The majority of tracer-coupled cells were retinal ganglion cells, and tracer coupling was not detected between SACs. The number of tracer-coupled cells significantly decreased after eye-opening and mostly disappeared by postnatal day 28 (P28). Membrane capacitance (Cm), an indicator of the formation of electrical coupling with gap junctions, was larger in SACs before than after eye-opening. The application of meclofenamic acid, a gap junction blocker, reduced the Cm of SACs. Gap junctional coupling by SACs was regulated by dopamine D1 receptors before eye-opening. In contrast, the reduction in gap junctional coupling after eye-opening was not affected by visual experience. At the mRNA level, 4 subtypes of connexins (23, 36, 43, and 45) were detected in SACs before eye-opening. Connexin 43 expression levels significantly decreased after eye-opening. These results indicate that gap junctional coupling by SACs occurs during the developmental period and suggest that the elimination of gap junctions proceeds with the innate system.
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7
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Kolibabka M, Dannehl M, Oezer K, Murillo K, Huang H, Riemann S, Hoffmann S, Gretz N, Schlotterer A, Feng Y, Hammes HP. Differences in junction-associated gene expression changes in three rat models of diabetic retinopathy with similar neurovascular phenotype. Neurobiol Dis 2023; 176:105961. [PMID: 36526091 DOI: 10.1016/j.nbd.2022.105961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/24/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
Diabetic retinopathy, also defined as microvascular complication of diabetes mellitus, affects the entire neurovascular unit with specific aberrations in every compartment. Neurodegeneration, glial activation and vasoregression are observed consistently in models of diabetic retinopathy. However, the order and the severity of these aberrations varies in different models, which is also true in patients. In this study, we analysed rat models of diabetic retinopathy with similar phenotypes to identify key differences in the pathogenesis. For this, we focussed on intercellular junction-associated gene expression, which are important for the communication and homeostasis within the neurovascular unit. Streptozotocin-injected diabetic Wistar rats, methylglyoxal supplemented Wistar rats and polycystin-2 transgenic (PKD) rats were analysed for neuroretinal function, vasoregression and retinal expression of junction-associated proteins. In all three models, neuroretinal impairment and vasoregression were observed, but gene expression profiling of junction-associated proteins demonstrated nearly no overlap between the three models. However, the differently expressed genes were from the main classes of claudins, connexins and integrins in all models. Changes in Rcor1 expression in diabetic rats and Egr1 expression in PKD rats confirmed the differences in upstream transcription factor level between the models. In PKD rats, a possible role for miRNA regulation was observed, indicated by an upregulation of miR-26b-5p, miR-122-5p and miR-300-3p, which was not observed in the other models. In silico allocation of connexins revealed not only differences in regulated subtypes, but also in affected retinal cell types, as well as connexin specific upstream regulators Sox7 and miR-92a-3p. In this study, we demonstrate that, despite their similar phenotype, models for diabetic retinopathy exhibit significant differences in their pathogenic pathways and primarily affected cell types. These results underline the importance for more sensitive diagnostic tools to identify pathogenic clusters in patients as the next step towards a desperately needed personalized therapy.
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Affiliation(s)
- Matthias Kolibabka
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany.
| | - Marcus Dannehl
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany
| | - Kübra Oezer
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Katharina Murillo
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany
| | - Hongpeng Huang
- Experimental Pharmacology, European Center for Angioscience, Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Strasse 13 - 17, 68167 Manheim, Germany
| | - Sarah Riemann
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany
| | - Sigrid Hoffmann
- Medical Research Center, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Norbert Gretz
- Medical Research Center, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Andrea Schlotterer
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany
| | - Yuxi Feng
- Experimental Pharmacology, European Center for Angioscience, Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Strasse 13 - 17, 68167 Manheim, Germany
| | - Hans-Peter Hammes
- 5th Medical Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; European Center for Angioscience, Ludolf-Krehl-Strasse 13 - 17, 68167 Mannheim, Germany
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8
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Žužul M, Lozić M, Filipović N, Čanović S, Didović Pavičić A, Petričević J, Kunac N, Šoljić V, Saraga-Babić M, Konjevoda S, Vukojevic K. The Expression of Connexin 37, 40, 43, 45 and Pannexin 1 in the Early Human Retina and Choroid Development and Tumorigenesis. Int J Mol Sci 2022; 23:5918. [PMID: 35682601 PMCID: PMC9180640 DOI: 10.3390/ijms23115918] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/08/2022] [Accepted: 05/23/2022] [Indexed: 02/01/2023] Open
Abstract
The expression pattern of Connexins (Cx) 37, 40, 43, 45 and Pannexin 1 (Pnx1) was analyzed immunohistochemically, as well as semi-quantitatively and quantitatively in histological sections of developing 8th- to 12th-week human eyes and postnatal healthy eye, in retinoblastoma and different uveal melanomas. Expressions of both Cx37 and Cx43 increased during development but diminished in the postnatal period, being higher in the retina than in the choroid. Cx37 was highly expressed in the choroid of retinoblastoma, and Cx43 in epitheloid melanoma, while they were both increasingly expressed in mixoid melanoma. In contrast, mild retinal Cx40 expression during development increased to strong in postnatal period, while it was significantly higher in the choroid of mixoid melanoma. Cx45 showed significantly higher expression in the developing retina compared to other samples, while it became low postnatally and in all types of melanoma. Pnx1 was increasingly expressed in developing choroid but became lower in the postnatal eye. It was strongly expressed in epithelial and spindle melanoma, and particularly in retinoblastoma. Our results indicate importance of Cx37 and Cx40 expression in normal and pathological vascularization, and Cx43 expression in inflammatory response. Whereas Cx45 is involved in early stages of eye development, Pnx1might influence cell metabolism. Additionally, Cx43 might be a potential biomarker of tumor prognosis.
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Affiliation(s)
- Matea Žužul
- Department of Ophthalmology, General Hospital Zadar, 21000 Split, Croatia; (M.Ž.); (S.Č.); (A.D.P.); (S.K.)
| | - Mirela Lozić
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia; (M.L.); (N.F.); (M.S.-B.)
| | - Natalija Filipović
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia; (M.L.); (N.F.); (M.S.-B.)
| | - Samir Čanović
- Department of Ophthalmology, General Hospital Zadar, 21000 Split, Croatia; (M.Ž.); (S.Č.); (A.D.P.); (S.K.)
- Department of Health Studies, University of Zadar, 23000 Zadar, Croatia
| | - Ana Didović Pavičić
- Department of Ophthalmology, General Hospital Zadar, 21000 Split, Croatia; (M.Ž.); (S.Č.); (A.D.P.); (S.K.)
| | - Joško Petričević
- Department of Pathology, School of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina;
| | - Nenad Kunac
- Department of Pathology, University Hospital of Split, 21000 Split, Croatia;
| | - Violeta Šoljić
- Department of Histology and Embryology, School of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina;
- Faculty of Health Studies, University of Mostar, 88000 Mostar, Bosnia and Herzegovina
| | - Mirna Saraga-Babić
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia; (M.L.); (N.F.); (M.S.-B.)
| | - Suzana Konjevoda
- Department of Ophthalmology, General Hospital Zadar, 21000 Split, Croatia; (M.Ž.); (S.Č.); (A.D.P.); (S.K.)
- Department of Health Studies, University of Zadar, 23000 Zadar, Croatia
| | - Katarina Vukojevic
- Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia; (M.L.); (N.F.); (M.S.-B.)
- Department of Histology and Embryology, School of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina;
- Department of Anatomy, School of Medicine, University of Mostar, 88000 Mostar, Bosnia and Herzegovina
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9
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Cheng L, Cring MR, Wadkins DA, Kuehn MH. Absence of Connexin 43 results in smaller retinas and arrested, depolarized retinal progenitor cells in human retinal organoids. Stem Cells 2022; 40:592-604. [PMID: 35263762 DOI: 10.1093/stmcls/sxac017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/18/2022] [Indexed: 11/14/2022]
Abstract
The development of the vertebrate retina relies on complex regulatory mechanisms to achieve its characteristic layered morphology containing multiple neuronal cell types. While connexin 43 (CX43) is not expressed by mature retinal neurons mutations in its gene GJA1 are associated with microphthalmia and low vision in patients. To delineate how lack of CX43 affects retinal development, GJA1 was disrupted in human induced pluripotent stem cells (hiPSCs) (GJA1-/-) using CRISPR/Cas9 editing, and these were subsequently differentiated into retinal organoids. GJA1-/- hiPSCs do not display defects in self-renewal and pluripotency, but the resulting organoids are smaller with a thinner neural retina and decreased abundance of many retinal cell types. CX43-deficient organoids express lower levels of the neural marker PAX6 and the retinal progenitor cell (RPC) markers PAX6, SIX3, and SIX6. Conversely, expression of the early neuroectoderm markers SOX1 and SOX2 remains high in GJA1-/- organoids throughout their development. Lack of CX43 results in an increased population of CHX10-positive RPCs that are smaller, disorganized, do not become polarized, and possess a limited ability to commit to retinal fate specification. Our data indicate that lack of CX43 causes a developmental arrest in RPCs that subsequently leads to pan-retinal defects and stunted ocular growth.
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Affiliation(s)
- Lin Cheng
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, USA.,Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, IA, USA
| | - Matthew R Cring
- Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - David A Wadkins
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, USA.,Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, IA, USA
| | - Markus H Kuehn
- Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, USA.,Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, IA, USA.,Institute for Vision Research, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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10
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van der Sande E, Haarman AEG, Quint WH, Tadema KCD, Meester-Smoor MA, Kamermans M, De Zeeuw CI, Klaver CCW, Winkelman BHJ, Iglesias AI. The Role of GJD2(Cx36) in Refractive Error Development. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 35262731 PMCID: PMC8934558 DOI: 10.1167/iovs.63.3.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/16/2022] [Indexed: 02/06/2023] Open
Abstract
Refractive errors are common eye disorders characterized by a mismatch between the focal power of the eye and its axial length. An increased axial length is a common cause of the refractive error myopia (nearsightedness). The substantial increase in myopia prevalence over the last decades has raised public health concerns because myopia can lead to severe ocular complications later in life. Genomewide association studies (GWAS) have made considerable contributions to the understanding of the genetic architecture of refractive errors. Among the hundreds of genetic variants identified, common variants near the gap junction delta-2 (GJD2) gene have consistently been reported as one of the top hits. GJD2 encodes the connexin 36 (Cx36) protein, which forms gap junction channels and is highly expressed in the neural retina. In this review, we provide current evidence that links GJD2(Cx36) to the development of myopia. We summarize the gap junctional communication in the eye and the specific role of GJD2(Cx36) in retinal processing of visual signals. Finally, we discuss the pathways involving dopamine and gap junction phosphorylation and coupling as potential mechanisms that may explain the role of GJD2(Cx36) in refractive error development.
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Affiliation(s)
- Emilie van der Sande
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
| | - Annechien E. G. Haarman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Wim H. Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kirke C. D. Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A. Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Biomedical Physics and Biomedical Photonics, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Chris I. De Zeeuw
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - Beerend H. J. Winkelman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adriana I. Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
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11
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Network Architecture of Gap Junctional Coupling among Parallel Processing Channels in the Mammalian Retina. J Neurosci 2020; 40:4483-4511. [PMID: 32332119 DOI: 10.1523/jneurosci.1810-19.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 03/27/2020] [Accepted: 04/12/2020] [Indexed: 01/04/2023] Open
Abstract
Gap junctions are ubiquitous throughout the nervous system, mediating critical signal transmission and integration, as well as emergent network properties. In mammalian retina, gap junctions within the Aii amacrine cell-ON cone bipolar cell (CBC) network are essential for night vision, modulation of day vision, and contribute to visual impairment in retinal degenerations, yet neither the extended network topology nor its conservation is well established. Here, we map the network contribution of gap junctions using a high-resolution connectomics dataset of an adult female rabbit retina. Gap junctions are prominent synaptic components of ON CBC classes, constituting 5%-25% of all axonal synaptic contacts. Many of these mediate canonical transfer of rod signals from Aii cells to ON CBCs for night vision, and we find that the uneven distribution of Aii signals to ON CBCs is conserved in rabbit, including one class entirely lacking direct Aii coupling. However, the majority of gap junctions formed by ON CBCs unexpectedly occur between ON CBCs, rather than with Aii cells. Such coupling is extensive, creating an interconnected network with numerous lateral paths both within, and particularly across, these parallel processing streams. Coupling patterns are precise with ON CBCs accepting and rejecting unique combinations of partnerships according to robust rulesets. Coupling specificity extends to both size and spatial topologies, thereby rivaling the synaptic specificity of chemical synapses. These ON CBC coupling motifs dramatically extend the coupled Aii-ON CBC network, with implications for signal flow in both scotopic and photopic retinal networks during visual processing and disease.SIGNIFICANCE STATEMENT Electrical synapses mediated by gap junctions are fundamental components of neural networks. In retina, coupling within the Aii-ON CBC network shapes visual processing in both the scotopic and photopic networks. In retinal degenerations, these same gap junctions mediate oscillatory activity that contributes to visual impairment. Here, we use high-resolution connectomics strategies to identify gap junctions and cellular partnerships. We describe novel, pervasive motifs both within and across classes of ON CBCs that dramatically extend the Aii-ON CBC network. These motifs are highly specific with implications for both signal processing within the retina and therapeutic interventions for blinding conditions. These findings highlight the underappreciated contribution of coupling motifs in retinal circuitry and the necessity of their detection in connectomics studies.
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12
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Traub RD, Moeller F, Rosch R, Baldeweg T, Whittington MA, Hall SP. Seizure initiation in infantile spasms vs. focal seizures: proposed common cellular mechanisms. Rev Neurosci 2020; 31:181-200. [PMID: 31525161 DOI: 10.1515/revneuro-2019-0030] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/01/2019] [Indexed: 11/15/2022]
Abstract
Infantile spasms (IS) and seizures with focal onset have different clinical expressions, even when electroencephalography (EEG) associated with IS has some degree of focality. Oddly, identical pathology (with, however, age-dependent expression) can lead to IS in one patient vs. focal seizures in another or even in the same, albeit older, patient. We therefore investigated whether the cellular mechanisms underlying seizure initiation are similar in the two instances: spasms vs. focal. We noted that in-common EEG features can include (i) a background of waves at alpha to delta frequencies; (ii) a period of flattening, lasting about a second or more - the electrodecrement (ED); and (iii) often an interval of very fast oscillations (VFO; ~70 Hz or faster) preceding, or at the beginning of, the ED. With IS, VFO temporally coincides with the motor spasm. What is different between the two conditions is this: with IS, the ED reverts to recurring slow waves, as occurring before the ED, whereas with focal seizures the ED instead evolves into an electrographic seizure, containing high-amplitude synchronized bursts, having superimposed VFO. We used in vitro data to help understand these patterns, as such data suggest cellular mechanisms for delta waves, for VFO, for seizure-related burst complexes containing VFO, and, more recently, for the ED. We propose a unifying mechanistic hypothesis - emphasizing the importance of brain pH - to explain the commonalities and differences of EEG signals in IS versus focal seizures.
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Affiliation(s)
- Roger D Traub
- IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Friederike Moeller
- Department of Clinical Neurophysiology, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Richard Rosch
- MRC Centre for Neurodevelopmental Disorders, King's College London, New Hunt's House, London SE1 1UL, UK
| | - Torsten Baldeweg
- Institute of Child Health, University College London, 30 Guildford Street, London WC1N 1EH, UK
| | | | - Stephen P Hall
- Hull York Medical School, University of York, Heslington YO10 5DD, UK
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13
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Kähne M, Rüdiger S, Kihara AH, Lindner B. Gap junctions set the speed and nucleation rate of stage I retinal waves. PLoS Comput Biol 2019; 15:e1006355. [PMID: 31034472 PMCID: PMC6508742 DOI: 10.1371/journal.pcbi.1006355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 05/09/2019] [Accepted: 11/27/2018] [Indexed: 11/18/2022] Open
Abstract
Spontaneous waves in the developing retina are essential in the formation of the retinotopic mapping in the visual system. From experiments in rabbits, it is known that the earliest type of retinal waves (stage I) is nucleated spontaneously, propagates at a speed of 451±91 μm/sec and relies on gap junction coupling between ganglion cells. Because gap junctions (electrical synapses) have short integration times, it has been argued that they cannot set the low speed of stage I retinal waves. Here, we present a theoretical study of a two-dimensional neural network of the ganglion cell layer with gap junction coupling and intrinsic noise. We demonstrate that this model can explain observed nucleation rates as well as the comparatively slow propagation speed of the waves. From the interaction between two coupled neurons, we estimate the wave speed in the model network. Furthermore, using simulations of small networks of neurons (N≤260), we estimate the nucleation rate in the form of an Arrhenius escape rate. These results allow for informed simulations of a realistically sized network, yielding values of the gap junction coupling and the intrinsic noise level that are in a physiologically plausible range.
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Affiliation(s)
- Malte Kähne
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- * E-mail:
| | - Sten Rüdiger
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Benjamin Lindner
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany
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14
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Kántor O, Szarka G, Benkő Z, Somogyvári Z, Pálfi E, Baksa G, Rácz G, Nitschke R, Debertin G, Völgyi B. Strategic Positioning of Connexin36 Gap Junctions Across Human Retinal Ganglion Cell Dendritic Arbors. Front Cell Neurosci 2018; 12:409. [PMID: 30524239 PMCID: PMC6262005 DOI: 10.3389/fncel.2018.00409] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/22/2018] [Indexed: 11/18/2022] Open
Abstract
Connexin36 (Cx36) subunits form gap junctions (GJ) between neurons throughout the central nervous system. Such GJs of the mammalian retina serve the transmission, averaging and correlation of signals prior to conveying visual information to the brain. Retinal GJs have been exhaustively studied in various animal species, however, there is still a perplexing paucity of information regarding the presence and function of human retinal GJs. Particularly little is known about GJ formation of human retinal ganglion cells (hRGCs) due to the limited number of suitable experimental approaches. Compared to the neuronal coupling studies in animal models, where GJ permeable tracer injection is the gold standard method, the post-mortem nature of scarcely available human retinal samples leaves immunohistochemistry as a sole approach to obtain information on hRGC GJs. In this study Lucifer Yellow (LY) dye injections and Cx36 immunohistochemistry were performed in fixed short-post-mortem samples to stain hRGCs with complete dendritic arbors and locate dendritic Cx36 GJs. Subsequent neuronal reconstructions and morphometric analyses revealed that Cx36 plaques had a clear tendency to form clusters and particularly favored terminal dendritic segments.
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Affiliation(s)
- Orsolya Kántor
- Department of Neuroanatomy, Faculty of Medicine, Institute for Anatomy and Cell Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, Pécs, Hungary.,Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Gergely Szarka
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, Pécs, Hungary.,Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary.,Center for Neuroscience, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Zsigmond Benkő
- Complex Systems and Computational Neuroscience Group, Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zoltán Somogyvári
- Complex Systems and Computational Neuroscience Group, Wigner Research Center for Physics, Hungarian Academy of Sciences, Budapest, Hungary
| | - Emese Pálfi
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Gábor Baksa
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Gergely Rácz
- Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Roland Nitschke
- Life Imaging Center, Center for Biological Systems Analysis, Albert-Ludwigs University, Freiburg, Germany.,BIOSS Center for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Gábor Debertin
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, Pécs, Hungary.,Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary.,Center for Neuroscience, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Béla Völgyi
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, Pécs, Hungary.,Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary.,Center for Neuroscience, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center, University of Pécs, Pécs, Hungary
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15
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Abstract
Major depressive disorder (MDD) is a chronic and debilitating illness that affects over 350 million people worldwide; however, current treatments have failed to cure or prevent the progress of depression. Increasing evidence suggests a crucial role for connexins in MDD. In this review, we have summarised recent accomplishments regarding the role of connexins, gap junctions, and hemichannels in the aetiology of MDD, and discussed the limitations of current research. A blockage of gap junctions or hemichannels induces depressive behaviour. Possible underlying mechanisms include the regulation of neurosecretory functions and synaptic activity by gap junctions and hemichannels. Gap junctions are functionally inhibited under stress conditions. Conversely, hemichannel permeability is increased. Antidepressants inhibit hemichannel permeability; however, they have contrasting effects on the function of gap junctions under normal conditions and can protect them against stress. In conclusion, the blockage of hemichannels concurrent with improvements in gap junction functionality might be potential targets for depression treatment.
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Affiliation(s)
- Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Tohru Yamakuni
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China.
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16
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Expression and function of connexin 43 protein in mouse and human retinal pigment epithelial cells as hemichannels and gap junction proteins. Exp Eye Res 2018; 168:128-137. [DOI: 10.1016/j.exer.2018.01.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 01/08/2023]
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17
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Kántor O, Varga A, Nitschke R, Naumann A, Énzsöly A, Lukáts Á, Szabó A, Németh J, Völgyi B. Bipolar cell gap junctions serve major signaling pathways in the human retina. Brain Struct Funct 2017; 222:2603-2624. [PMID: 28070649 DOI: 10.1007/s00429-016-1360-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/22/2016] [Indexed: 11/26/2022]
Abstract
Connexin36 (Cx36) constituent gap junctions (GJ) throughout the brain connect neurons into functional syncytia. In the retina they underlie the transmission, averaging and correlation of signals prior conveying visual information to the brain. This is the first study that describes retinal bipolar cell (BC) GJs in the human inner retina, whose function is enigmatic even in the examined animal models. Furthermore, a number of unique features (e.g. fovea, trichromacy, midget system) necessitate a reexamination of the animal model results in the human retina. Well-preserved postmortem human samples of this study are allowed to identify Cx36 expressing BCs neurochemically. Results reveal that both rod and cone pathway interneurons display strong Cx36 expression. Rod BC inputs to AII amacrine cells (AC) appear in juxtaposition to AII GJs, thus suggesting a strategic AII cell targeting by rod BCs. Cone BCs serving midget, parasol or koniocellular signaling pathways display a wealth of Cx36 expression to form homologously coupled arrays. In addition, they also establish heterologous GJ contacts to serve an exchange of information between parallel signaling streams. Interestingly, a prominent Cx36 expression was exhibited by midget system BCs that appear to maintain intimate contacts with bistratified BCs serving other pathways. These findings suggest that BC GJs in parallel signaling streams serve both an intra- and inter-pathway exchange of signals in the human retina.
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Affiliation(s)
- Orsolya Kántor
- Department of Neuroanatomy, Faculty of Medicine, Institute for Anatomy and Cell Biology, University of Freiburg, 79104, Freiburg, Germany
- MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, 7624, Hungary
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Alexandra Varga
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Roland Nitschke
- Life Imaging Center, Center for Biological Systems Analysis, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - Angela Naumann
- Life Imaging Center, Center for Biological Systems Analysis, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - Anna Énzsöly
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
- Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
| | - Ákos Lukáts
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Arnold Szabó
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - János Németh
- Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
| | - Béla Völgyi
- MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, 7624, Hungary.
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, 7624, Hungary.
- János Szentágothai Research Center, University of Pécs, Ifjúság street 20, Pécs, 7624, Hungary.
- Department of Ophthalmology, New York University Langone Medical Center, New York, NY, 10016, USA.
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18
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Theofilas P, Steinhäuser C, Theis M, Derouiche A. Morphological study of a connexin 43-GFP reporter mouse highlights glial heterogeneity, amacrine cells, and olfactory ensheathing cells. J Neurosci Res 2017; 95:2182-2194. [PMID: 28370142 DOI: 10.1002/jnr.24055] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 11/09/2022]
Abstract
Connexin 43 (Cx43) is the main astrocytic connexin and forms the basis of the glial syncytium. The morphology of connexin-expressing cells can be best studied in transgenic mouse lines expressing cytoplasmic fluorescent reporters, since immunolabeling the plaques can obscure the shapes of the individual cells. The Cx43kiECFP mouse generated by Degen et al. (FASEBJ 26:4576, 2012) expresses cytosolic ECFP and has previously been used to establish that Cx43 may not be expressed by all astrocytes within a population, and this can vary in a region-dependent way. To establish this mouse line as a tool for future astrocyte and connexin research, we sought to consolidate reporter authenticity, studying cell types and within-region population heterogeneity. Applying anti-GFP, all cell types related to astroglia were positive-namely, protoplasmic astrocytes in the hippocampus, cortex, thalamus, spinal cord, olfactory bulb, cerebellum with Bergmann glia and astrocytes also in the molecular layer, and retinal Müller cells and astrocytes. Labeled cell types further comprise white matter astrocytes, olfactory ensheathing cells, radial glia-like stem cells, retinal pigment epithelium cells, ependymal cells, and meningeal cells. We furthermore describe a retinal Cx43-expressing amacrine cell morphologically reminiscent of ON-OFF wide-field amacrine cells, representing the first example of a mammalian CNS neuron-expressing Cx43 protein. In double staining with cell type-specific markers (GFAP, S100ß, glutamine synthetase), Cx43 reporter expression in the hippocampus and cortex was restricted to GFAP+ astrocytes. Altogether, this mouse line is a highly reliable tool for studies of Cx43-expressing CNS cells and astroglial cell morphology. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Panos Theofilas
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany.,Memory and Aging Center, Department of Neurology, University of California, San Francisco
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Martin Theis
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Amin Derouiche
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany.,Dr. Senckenbergische Anatomie, Institute for Anatomy II, Goethe-University, Frankfurt am Main, Germany
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19
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Pannicke T, Ivo Chao T, Reisenhofer M, Francke M, Reichenbach A. Comparative electrophysiology of retinal Müller glial cells-A survey on vertebrate species. Glia 2016; 65:533-568. [PMID: 27767232 DOI: 10.1002/glia.23082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/15/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022]
Abstract
Müller cells are the dominant macroglial cells in the retina of all vertebrates. They fulfill a variety of functions important for retinal physiology, among them spatial buffering of K+ ions and uptake of glutamate and other neurotransmitters. To this end, Müller cells express inwardly rectifying K+ channels and electrogenic glutamate transporters. Moreover, a lot of voltage- and ligand-gated ion channels, aquaporin water channels, and electrogenic transporters are expressed in Müller cells, some of them in a species-specific manner. For example, voltage-dependent Na+ channels are found exclusively in some but not all mammalian species. Whereas a lot of data exist from amphibians and mammals, the results from other vertebrates are sparse. It is the aim of this review to present a survey on Müller cell electrophysiology covering all classes of vertebrates. The focus is on functional studies, mainly performed using the whole-cell patch-clamp technique. However, data about the expression of membrane channels and transporters from immunohistochemistry are also included. Possible functional roles of membrane channels and transporters are discussed. Obviously, electrophysiological properties involved in the main functions of Müller cells developed early in vertebrate evolution. GLIA 2017;65:533-568.
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Affiliation(s)
- Thomas Pannicke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
| | - T Ivo Chao
- Institute of Anatomy and Cell Biology, Medical School Göttingen, Germany
| | - Miriam Reisenhofer
- Department of Chemistry, University of Zürich, Switzerland
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Mike Francke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
- Sächsischer Inkubator für klinische Translation (SIKT), Universität Leipzig, Germany
| | - Andreas Reichenbach
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
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20
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Kántor O, Benkő Z, Énzsöly A, Dávid C, Naumann A, Nitschke R, Szabó A, Pálfi E, Orbán J, Nyitrai M, Németh J, Szél Á, Lukáts Á, Völgyi B. Characterization of connexin36 gap junctions in the human outer retina. Brain Struct Funct 2016; 221:2963-84. [PMID: 26173976 DOI: 10.1007/s00429-015-1082-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
Abstract
Retinal connexins (Cx) form gap junctions (GJ) in key circuits that transmit average or synchronize signals. Expression of Cx36, -45, -50 and -57 have been described in many species but there is still a disconcerting paucity of information regarding the Cx makeup of human retinal GJs. We used well-preserved human postmortem samples to characterize Cx36 GJ constituent circuits of the outer plexiform layer (OPL). Based on their location, morphometric characteristics and co-localizations with outer retinal neuronal markers, we distinguished four populations of Cx36 plaques in the human OPL. Three of these were comprised of loosely scattered Cx36 plaques; the distalmost population 1 formed cone-to-rod GJs, population 2 in the mid-OPL formed cone-to-cone GJs, whereas the proximalmost population 4 likely connected bipolar cell dendrites. The fourth population (population 3) of Cx36 plaques conglomerated beneath cone pedicles and connected dendritic tips of bipolar cells that shared a common presynaptic cone. Overall, we show that the human outer retina displays a diverse cohort of Cx36 GJ that follows the general mammalian scheme and display a great functional diversity.
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Affiliation(s)
- Orsolya Kántor
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Zsigmond Benkő
- Department of Theory, Wigner Research Center for Physics of the Hungarian Academy of Sciences, Budapest, 1121, Hungary
- Semmelweis University School of Ph.D. Studies, Budapest, 1085, Hungary
| | - Anna Énzsöly
- Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Csaba Dávid
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Angela Naumann
- Life Imaging Center, Center for Biological Systems Analysis, Albert-Ludwigs University, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany
| | - Roland Nitschke
- Life Imaging Center, Center for Biological Systems Analysis, Albert-Ludwigs University, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany
| | - Arnold Szabó
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Emese Pálfi
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - József Orbán
- Department of Biophysics, University of Pécs, Pécs, 7624, Hungary
- János Szentágothai Research Center, University of Pécs, Ifjúság str. 6, 7624, Pécs, Hungary
| | - Miklós Nyitrai
- Department of Biophysics, University of Pécs, Pécs, 7624, Hungary
- János Szentágothai Research Center, University of Pécs, Ifjúság str. 6, 7624, Pécs, Hungary
| | - János Németh
- Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
| | - Ágoston Szél
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Ákos Lukáts
- Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Béla Völgyi
- János Szentágothai Research Center, University of Pécs, Ifjúság str. 6, 7624, Pécs, Hungary.
- MTA-PTE NAP B Retinal Electrical Synapses Research Group, Pécs, 7624, Hungary.
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, 7624, Hungary.
- Department of Ophthalmology, New York University Langone Medical Center, New York, NY, 10016, USA.
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21
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Tu HY, Chiao CC. Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina. Dev Neurobiol 2016; 76:473-86. [PMID: 26084632 DOI: 10.1002/dneu.22320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/09/2015] [Accepted: 06/11/2015] [Indexed: 12/20/2022]
Abstract
Gap junctions are composed of connexin 36 (Cx36) and play a critical role in the rod photoreceptor signaling pathways of the vertebrate retina. Despite the fact that their connection and modulation in various rod pathways have been extensively studied in adult animals, little is known about the contribution and regulation of gap junctions to the development of the AII amacrine cell (AC)-mediated rod pathway. Using immunohistochemistry and microinjection, this study demonstrates a steady increase in relative Cx36 protein expression in both plexiform layers of the rabbit retina at around the time of eye opening. However, immediately after eye opening, most Cx36 immunoreactive AII ACs show no gap junction coupling pattern to neighboring cells and it is not until the third postnatal week that AII cells begin to exhibit an adult-like tracer-coupling pattern. Moreover, studies using dark-rearing and AMPA receptor blockade during postnatal development both revealed that relative levels of Cx36 immunoreactivity in AII ACs were increased when neural activity was inhibited. Our findings suggest that Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina.
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Affiliation(s)
- Hung-Ya Tu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chuan-Chin Chiao
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, 30013, Taiwan
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22
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Bolte P, Herrling R, Dorgau B, Schultz K, Feigenspan A, Weiler R, Dedek K, Janssen-Bienhold U. Expression and Localization of Connexins in the Outer Retina of the Mouse. J Mol Neurosci 2015; 58:178-92. [PMID: 26453550 DOI: 10.1007/s12031-015-0654-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/08/2015] [Indexed: 01/30/2023]
Abstract
The identification of the proteins that make up the gap junction channels between rods and cones is of crucial importance to understand the functional role of photoreceptor coupling within the retinal network. In vertebrates, connexin proteins constitute the structural components of gap junction channels. Connexin36 is known to be expressed in cones whereas extensive investigations have failed to identify the corresponding connexin expressed in rods. Using immunoelectron microscopy, we demonstrate that connexin36 (Cx36) is present in gap junctions of cone but not rod photoreceptors in the mouse retina. To identify the rod connexin, we used nested reverse transcriptase polymerase chain reaction and tested retina and photoreceptor samples for messenger RNA (mRNA) expression of all known connexin genes. In addition to connexin36, we detected transcripts for connexin32, connexin43, connexin45, connexin50, and connexin57 in photoreceptor samples. Immunohistochemistry showed that connexin43, connexin45, connexin50, and connexin57 proteins are expressed in the outer plexiform layer. However, none of these connexins was detected at gap junctions between rods and cones as a counterpart of connexin36. Therefore, the sought-after rod protein must be either an unknown connexin sequence, a connexin36 splice product not detected by our antibodies, or a protein from a further gap junction protein family.
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Affiliation(s)
- Petra Bolte
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany.,Animal Navigation, University of Oldenburg, 26111, Oldenburg, Germany
| | - Regina Herrling
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany
| | - Birthe Dorgau
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany.,Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Konrad Schultz
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany
| | - Andreas Feigenspan
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany.,Animal Physiology, FAU Erlangen-Nuremberg, 91058, Erlangen, Germany
| | - Reto Weiler
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, 26111, Oldenburg, Germany
| | - Karin Dedek
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany. .,Research Center Neurosensory Science, University of Oldenburg, 26111, Oldenburg, Germany.
| | - Ulrike Janssen-Bienhold
- Neurobiology Group, Department for Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany. .,Research Center Neurosensory Science, University of Oldenburg, 26111, Oldenburg, Germany.
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23
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24
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Kovács-Öller T, Raics K, Orbán J, Nyitrai M, Völgyi B. Developmental changes in the expression level of connexin36 in the rat retina. Cell Tissue Res 2014; 358:289-302. [PMID: 25110193 DOI: 10.1007/s00441-014-1967-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 07/09/2014] [Indexed: 02/03/2023]
Abstract
Connexin36 (Cx36) is the major gap junction forming protein in the brain and the retina; thus, alterations in its expression indicate changes in the corresponding circuitry. Many structural changes occur in the early postnatal retina before functional neuronal circuits are finalized, including those that incorporate gap junctions. To reveal the time-lapse formation of inner retinal gap junctions, we examine the developing postnatal rat retina from birth (P0) to young adult age (P20) and follow the expression of Cx36 in the mRNA and protein levels. We found a continuous elevation in the expression of both the Cx36 transcript and protein between P0 and P20 and a somewhat delayed Cx36 plaque formation throughout the inner plexiform layer (IPL) starting at P10. By using tristratificated calretinin positive (CaR(+)) fibers in the IPL as a guide, we detected a clear preference of Cx36 plaques for the ON sublamina from the earliest time of detection. This distributional preference became more pronounced at P15 and P20 due to the emergence and widespread expression of large (>0.1 μm(2)) Cx36 plaques in the ON sublamina. Finally, we showed that parvalbumin-positive (PV(+)) AII amacrine cell dendrites colocalize with Cx36 plaques as early as P10 in strata 3 and 4, whereas colocalizations in stratum 5 became characteristic only around P20. We conclude that Cx36 expression in the rat IPL displays a characteristic succession of changes during retinogenesis reflecting the formation of the underlying electrical synaptic circuitry. In particular, AII cell gap junctions, first formed with ON cone bipolar cells and later with other AII amacrine cells, accounted for the observed Cx36 expressional changes.
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Affiliation(s)
- Tamás Kovács-Öller
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Ifjúság street 6, Hungary
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25
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Palacios-Muñoz A, Escobar MJ, Vielma A, Araya J, Astudillo A, Valdivia G, García IE, Hurtado J, Schmachtenberg O, Martínez AD, Palacios AG. Role of connexin channels in the retinal light response of a diurnal rodent. Front Cell Neurosci 2014; 8:249. [PMID: 25202238 PMCID: PMC4142540 DOI: 10.3389/fncel.2014.00249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/05/2014] [Indexed: 01/02/2023] Open
Abstract
Several studies have shown that connexin channels play an important role in retinal neural coding in nocturnal rodents. However, the contribution of these channels to signal processing in the retina of diurnal rodents remains unclear. To gain insight into this problem, we studied connexin expression and the contribution of connexin channels to the retinal light response in the diurnal rodent Octodon degus (degu) compared to rat, using in vivo ERG recording under scotopic and photopic light adaptation. Analysis of the degu genome showed that the common retinal connexins present a high degree of homology to orthologs expressed in other mammals, and expression of Cx36 and Cx43 was confirmed in degu retina. Cx36 localized mainly to the outer and inner plexiform layers (IPLs), while Cx43 was expressed mostly in cells of the retinal pigment epithelium. Under scotopic conditions, the b-wave response amplitude was strongly reduced by 18-β-glycyrrhetinic acid (β-GA) (−45.1% in degu, compared to −52.2% in rat), suggesting that connexins are modulating this response. Remarkably, under photopic adaptation, β-GA increased the ERG b-wave amplitude in degu (+107.2%) while reducing it in rat (−62.3%). Moreover, β-GA diminished the spontaneous action potential firing rate in ganglion cells (GCs) and increased the response latency of ON and OFF GCs. Our results support the notion that connexins exert a fine-tuning control of the retinal light response and have an important role in retinal neural coding.
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Affiliation(s)
- Angelina Palacios-Muñoz
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Maria J Escobar
- Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile
| | - Alex Vielma
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Joaquín Araya
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Aland Astudillo
- Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile
| | - Gonzalo Valdivia
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Isaac E García
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - José Hurtado
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile
| | - Oliver Schmachtenberg
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Agustín D Martínez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Adrian G Palacios
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile
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26
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Muto T, Tien T, Kim D, Sarthy VP, Roy S. High glucose alters Cx43 expression and gap junction intercellular communication in retinal Müller cells: promotes Müller cell and pericyte apoptosis. Invest Ophthalmol Vis Sci 2014; 55:4327-37. [PMID: 24938518 DOI: 10.1167/iovs.14-14606] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To investigate whether high glucose (HG) alters connexin 43 (Cx43) expression and gap junction intercellular communication (GJIC) activity in retinal Müller cells, and promotes Müller cell and pericyte loss. METHODS Retinal Müller cells (rMC-1) and cocultures of rMC-1 and retinal pericytes were grown in normal (N) or HG (30 mM glucose) medium. Additionally, rMC-1 transfected with Cx43 small interfering RNA (siRNA) were grown as cocultures with pericytes, and rMC-1 transfected with Cx43 plasmid were grown in HG. Expression of Cx43 was determined by Western blotting and immunostaining and GJIC was assessed by scrape-loading dye transfer (SLDT) technique. Apoptosis was analyzed by TUNEL or differential staining assay, and Akt activation by assessing Akt phosphorylation. RESULTS In monocultures of rMC-1 and cocultures of rMC-1 and pericytes, Cx43 protein level, number of Cx43 plaques, GJIC, and Akt phosphorylation were significantly reduced in HG medium. Number of TUNEL-positive cells was also significantly increased in rMC-1 monocultures and in rMC-1 and pericyte cocultures grown in HG medium. Importantly, when rMC-1 transfected with Cx43 siRNA were grown as cocultures with pericytes, a significant decrease in GJIC, and increase in TUNEL-positive cells was observed, concomitant with decreased Akt phosphorylation. Upregulation of Cx43 rescued rMC-1 from HG-induced apoptosis. CONCLUSIONS Gap junction communication between Müller cells and pericytes is essential for their survival. Downregulation of Cx43 that is HG induced and impairment of GJIC activity in Müller cells contributes to loss of glial and vascular cells associated with the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Tetsuya Muto
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Thomas Tien
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Dongjoon Kim
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Vijay P Sarthy
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
| | - Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
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27
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Völgyi B, Kovács-Oller T, Atlasz T, Wilhelm M, Gábriel R. Gap junctional coupling in the vertebrate retina: variations on one theme? Prog Retin Eye Res 2013; 34:1-18. [PMID: 23313713 DOI: 10.1016/j.preteyeres.2012.12.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/18/2012] [Accepted: 12/28/2012] [Indexed: 10/27/2022]
Abstract
Gap junctions connect cells in the bodies of all multicellular organisms, forming either homologous or heterologous (i.e. established between identical or different cell types, respectively) cell-to-cell contacts by utilizing identical (homotypic) or different (heterotypic) connexin protein subunits. Gap junctions in the nervous system serve electrical signaling between neurons, thus they are also called electrical synapses. Such electrical synapses are particularly abundant in the vertebrate retina where they are specialized to form links between neurons as well as glial cells. In this article, we summarize recent findings on retinal cell-to-cell coupling in different vertebrates and identify general features in the light of the evergrowing body of data. In particular, we describe and discuss tracer coupling patterns, connexin proteins, junctional conductances and modulatory processes. This multispecies comparison serves to point out that most features are remarkably conserved across the vertebrate classes, including (i) the cell types connected via electrical synapses; (ii) the connexin makeup and the conductance of each cell-to-cell contact; (iii) the probable function of each gap junction in retinal circuitry; (iv) the fact that gap junctions underlie both electrical and/or tracer coupling between glial cells. These pan-vertebrate features thus demonstrate that retinal gap junctions have changed little during the over 500 million years of vertebrate evolution. Therefore, the fundamental architecture of electrically coupled retinal circuits seems as old as the retina itself, indicating that gap junctions deeply incorporated in retinal wiring from the very beginning of the eye formation of vertebrates. In addition to hard wiring provided by fast synaptic transmitter-releasing neurons and soft wiring contributed by peptidergic, aminergic and purinergic systems, electrical coupling may serve as the 'skeleton' of lateral processing, enabling important functions such as signal averaging and synchronization.
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Affiliation(s)
- Béla Völgyi
- Department of Ophthalmology, School of Medicine, New York University, 550 First Avenue, MSB 149, New York, NY 10016, USA.
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28
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Paschon V, Higa GSV, Resende RR, Britto LRG, Kihara AH. Blocking of connexin-mediated communication promotes neuroprotection during acute degeneration induced by mechanical trauma. PLoS One 2012; 7:e45449. [PMID: 23029016 PMCID: PMC3447938 DOI: 10.1371/journal.pone.0045449] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 08/22/2012] [Indexed: 01/27/2023] Open
Abstract
Accruing evidence indicates that connexin (Cx) channels in the gap junctions (GJ) are involved in neurodegeneration after injury. However, studies using KO animal models endowed apparently contradictory results in relation to the role of coupling in neuroprotection. We analyzed the role of Cx-mediated communication in a focal lesion induced by mechanical trauma of the retina, a model that allows spatial and temporal definition of the lesion with high reproducibility, permitting visualization of the focus, penumbra and adjacent areas. Cx36 and Cx43 exhibited distinct gene expression and protein levels throughout the neurodegeneration progress. Cx36 was observed close to TUNEL-positive nuclei, revealing the presence of this protein surrounding apoptotic cells. The functional role of cell coupling was assessed employing GJ blockers and openers combined with lactate dehydrogenase (LDH) assay, a direct method for evaluating cell death/viability. Carbenoxolone (CBX), a broad-spectrum GJ blocker, reduced LDH release after 4 hours, whereas quinine, a Cx36-channel specific blocker, decreased LDH release as early as 1 hour after lesion. Furthermore, analysis of dying cell distribution confirmed that the use of GJ blockers reduced apoptosis spread. Accordingly, blockade of GJ communication during neurodegeneration with quinine, but not CBX, caused downregulation of initial and effector caspases. To summarize, we observed specific changes in Cx gene expression and protein distribution during the progress of retinal degeneration, indicating the participation of these elements in acute neurodegeneration processes. More importantly, our results revealed that direct control of GJ channels permeability may take part in reliable neuroprotection strategies aimed to rapid, fast treatment of mechanical trauma in the retina.
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Affiliation(s)
- Vera Paschon
- Núcleo de Cognição e Sistemas Complexos, Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, São Paulo, Brazil
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Guilherme Shigueto Vilar Higa
- Núcleo de Cognição e Sistemas Complexos, Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, São Paulo, Brazil
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Rodrigo Ribeiro Resende
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Luiz Roberto G. Britto
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Alexandre Hiroaki Kihara
- Núcleo de Cognição e Sistemas Complexos, Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, São Paulo, Brazil
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, São Paulo, Brazil
- * E-mail:
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Ballios BG, Clarke L, Coles BLK, Shoichet MS, Van Der Kooy D. The adult retinal stem cell is a rare cell in the ciliary epithelium whose progeny can differentiate into photoreceptors. Biol Open 2012; 1:237-46. [PMID: 23213414 PMCID: PMC3507281 DOI: 10.1242/bio.2012027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Self-renewing, multipotential retinal stem cells (RSCs) reside in the pigmented ciliary epithelium of the peripheral retina in adult mammals. RSCs can give rise to rhodopsin positive-cells, which can integrate into early postnatal retina, and represent a potentially useful option for cellular therapy. The ability to purify a stem cell population and direct the differentiation toward a particular cell lineage is a challenge facing the application of stem cells in regenerative medicine. Here we use cell sorting to prospectively enrich mouse RSCs based on size, granularity and low expression of P-cadherin and demonstrate that only rare cells with defined properties proliferate to form colonies. We show that clonally-derived mouse and human RSC progeny are multipotent and can differentiate into mature rhodopsin-positive cells with high efficiency using combinations of exogenous culture additives known to influence neural retinal development, including taurine and retinoic acid. This directed RSC differentiation follows the temporal sequence of photoreceptor differentiation in vivo, and the cells exhibit morphology, protein and gene expression consistent with primary cultures of rods in vitro. These results demonstrate that the RSC, an adult stem cell, can be enriched and directed to produce photoreceptors as a first step toward a targeted cell replacement strategy to treat retinal degenerative disease.
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Affiliation(s)
- Brian G Ballios
- Institute of Medical Science, University of Toronto, 1 King's College Circle , Toronto, Ontario M5S 1A8 , Canada
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30
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Tian C, Zhao T, Zeng Y, Yin ZQ. Increased Müller cell de-differentiation after grafting of retinal stem cell in the sub-retinal space of Royal College of Surgeons rats. Tissue Eng Part A 2011; 17:2523-32. [PMID: 21609182 DOI: 10.1089/ten.tea.2010.0649] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In several vertebrate classes, the Müller glia are capable of de-differentiating, proliferating, and acquiring a progenitor-like state in response to acute retinal injury or in response to exogenous growth factors. Our previous study has shown that Müller cells can be activated and de-differentiated into retinal progenitors during Royal College of Surgeons (RCS) rats' degeneration, although the limited proliferation cannot maintain retinal function. We now report that rat retinal stem cells (rSCs) transplanted into RCS rats slowed the progression of retinal morphological degeneration and prevented the functional disruption. Further, we found that retinal progenitor cells labeled with Chx10 were increased significantly after rSCs transplantation, and most of them are mainly from activated Müller cells. rSCs transplantation also enhances neurogenic potential by producing more recoverin-positive photoreceptors, which was proved coming from Müller glia-derived cells. These results provide evidence that stem cell-based therapy may offer a novel therapeutic approach for the treatment of retinal degeneration, and that Müller glia in mammalian retina can be activated and de-differentiated by rSC transplantation and may have therapeutic effects.
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Affiliation(s)
- Chunyu Tian
- Southwest Hospital, Southwest Eye Hospital, Third Military Medical University, Chongqing, China
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31
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Blankenship AG, Hamby AM, Firl A, Vyas S, Maxeiner S, Willecke K, Feller MB. The role of neuronal connexins 36 and 45 in shaping spontaneous firing patterns in the developing retina. J Neurosci 2011; 31:9998-10008. [PMID: 21734291 PMCID: PMC3142875 DOI: 10.1523/jneurosci.5640-10.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 05/17/2011] [Accepted: 05/23/2011] [Indexed: 12/27/2022] Open
Abstract
Gap junction coupling synchronizes activity among neurons in adult neural circuits, but its role in coordinating activity during development is less known. The developing retina exhibits retinal waves--spontaneous depolarizations that propagate among retinal interneurons and drive retinal ganglion cells (RGCs) to fire correlated bursts of action potentials. During development, two connexin isoforms, connexin 36 (Cx36) and Cx45, are expressed in bipolar cells and RGCs, and therefore provide a potential substrate for coordinating network activity. To determine whether gap junctions contribute to retinal waves, we compared spontaneous activity patterns using calcium imaging, whole-cell recording, and multielectrode array recording in control, single-knock-out (ko) mice lacking Cx45 and double-knock-out (dko) mice lacking both isoforms. Wave frequency, propagation speed, and bias in propagation direction were similar in control, Cx36ko, Cx45ko, and Cx36/45dko retinas. However, the spontaneous firing rate of individual retinal ganglion cells was elevated in Cx45ko retinas, similar to Cx36ko retinas (Hansen et al., 2005; Torborg and Feller, 2005), a phenotype that was more pronounced in Cx36/45dko retinas. As a result, spatial correlations, as assayed by nearest-neighbor correlation and functional connectivity maps, were significantly altered. In addition, Cx36/45dko mice had reduced eye-specific segregation of retinogeniculate afferents. Together, these findings suggest that although Cx36 and Cx45 do not play a role in gross spatial and temporal propagation properties of retinal waves, they strongly modulate the firing pattern of individual RGCs, ensuring strongly correlated firing between nearby RGCs and normal patterning of retinogeniculate projections.
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Affiliation(s)
- Aaron G. Blankenship
- Neurosciences Graduate Program, University of California, San Diego, La Jolla, California 92093
- Department of Molecular and Cell Biology
| | | | - Alana Firl
- Vision Sciences Graduate Program, Department of Optometry, and
| | - Shri Vyas
- Department of Molecular and Cell Biology
| | - Stephan Maxeiner
- LIMES (Life and Medical Sciences) Institute, University of Bonn, 53115 Bonn, Germany
| | - Klaus Willecke
- LIMES (Life and Medical Sciences) Institute, University of Bonn, 53115 Bonn, Germany
| | - Marla B. Feller
- Department of Molecular and Cell Biology
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California 94720, and
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Kihara AH, Santos TO, Osuna-Melo EJ, Paschon V, Vidal KSM, Akamine PS, Castro LM, Resende RR, Hamassaki DE, Britto LRG. Connexin-mediated communication controls cell proliferation and is essential in retinal histogenesis. Int J Dev Neurosci 2009; 28:39-52. [PMID: 19800961 DOI: 10.1016/j.ijdevneu.2009.09.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 09/09/2009] [Accepted: 09/24/2009] [Indexed: 12/29/2022] Open
Abstract
Connexin (Cx) channels and hemichannels are involved in essential processes during nervous system development such as apoptosis, propagation of spontaneous activity and interkinetic nuclear movement. In the first part of this study, we extensively characterized Cx gene and protein expression during retinal histogenesis. We observed distinct spatio-temporal patterns among studied Cx and an overriding, ubiquitous presence of Cx45 in progenitor cells. The role of Cx-mediated communication was assessed by using broad-spectrum (carbenoxolone, CBX) and Cx36/Cx50 channel-specific (quinine) blockers. In vivo application of CBX, but not quinine, caused remarkable reduction in retinal thickness, suggesting changes in cell proliferation/apoptosis ratio. Indeed, we observed a decreased number of mitotic cells in CBX-injected retinas, with no significant changes in the expression of PCNA, a marker for cells in proliferative state. Taken together, our results pointed a pivotal role of Cx45 in the developing retina. Moreover, this study revealed that Cx-mediated communication is essential in retinal histogenesis, particularly in the control of cell proliferation.
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Affiliation(s)
- Alexandre H Kihara
- Núcleo de Cognição e Sistemas Complexos, Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, SP, Brazil.
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Cook JE, Becker DL. Gap-Junction Proteins in Retinal Development: New Roles for the “Nexus”. Physiology (Bethesda) 2009; 24:219-30. [DOI: 10.1152/physiol.00007.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Gap-junction channels, the cytoplasmic proteins that associate with them, and the transcriptional networks that regulate them are increasingly being viewed as critical communications hubs for cell signaling in health and disease. As a result, the term “nexus,” which was the original structural name for these focal intercellular links, is coming back into use with new proteomic and transcriptomic meanings. The retina is better understood than any other part of the vertebrate central nervous system in respect of its developmental patterning, its diverse neuronal types and circuits, and the emergence of its definitive structure-function correlations. Thus, studies of the junctional and nonjunctional nexus roles of gap-junction proteins in coordinating retinal development should throw useful light on cell signaling in other developing nervous tissues.
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Affiliation(s)
- Jeremy E. Cook
- Department of Cell and Developmental Biology, University College London, Gower Street, London, United Kingdom
| | - David L. Becker
- Department of Cell and Developmental Biology, University College London, Gower Street, London, United Kingdom
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Leonelli M, Martins DO, Kihara AH, Britto LRG. Ontogenetic expression of the vanilloid receptors TRPV1 and TRPV2 in the rat retina. Int J Dev Neurosci 2009; 27:709-18. [PMID: 19619635 DOI: 10.1016/j.ijdevneu.2009.07.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 06/06/2009] [Accepted: 07/11/2009] [Indexed: 01/13/2023] Open
Abstract
The present study aimed to analyze the gene and protein expression and the pattern of distribution of the vanilloid receptors TRPV1 and TRPV2 in the developing rat retina. During the early phases of development, TRPV1 was found mainly in the neuroblastic layer of the retina and in the pigmented epithelium. In the adult, TRPV1 was found in microglial cells, blood vessels, astrocytes and in neuronal structures, namely synaptic boutons of both retinal plexiform layers, as well as in cell bodies of the inner nuclear layer and the ganglion cell layer. The pattern of distribution of TRPV1 was mainly punctate, and there was higher TRPV1 labeling in the peripheral retina than in central regions. TRPV2 expression was quite distinct. Its expression was virtually undetectable by immunoblotting before P1, and that receptor was found by immunohistochemistry only by postnatal day 15 (P15). RNA and protein analysis showed that the adult levels are only reached by P60, which includes small processes in the retinal plexiform layers, and labeled cellular bodies in the inner nuclear layer and the ganglion cell layer. There was no overlapping between the signal observed for both receptors. In conclusion, our results showed that the patterns of distribution of TRPV1 and TRPV2 are different during the development of the rat retina, suggesting that they have specific roles in both visual processing and in providing specific cues to neural development.
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Affiliation(s)
- Mauro Leonelli
- Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
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Kihara AH, Paschon V, Akamine PS, Saito KC, Leonelli M, Jiang JX, Hamassaki DE, Britto LRG. Differential expression of connexins during histogenesis of the chick retina. Dev Neurobiol 2009; 68:1287-302. [PMID: 18506822 DOI: 10.1002/dneu.20652] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gap junction (GJ) channels couple adjacent cells, allowing transfer of second messengers, ions, and molecules up to 1 kDa. These channels are composed by a multigene family of integral membrane proteins called connexins (Cx). In the retina, besides being essential circuit element in the visual processing, GJ channels also play important roles during its development. Herein, we analyzed Cx43, Cx45, Cx50, and Cx56 expression during chick retinal histogenesis. Cx exhibited distinct expression profiles during retinal development, except for Cx56, whose expression was not detected. Cx43 immunolabeling was observed at early development, in the transition of ventricular zone and pigmented epithelium. Later, Cx43 was seen in the outer plexiform and ganglion cell layers, and afterwards also in the inner plexiform layer. We observed remarkable changes in the phosphorylation status of this protein, which indicated modifications in functional properties of this Cx during retinal histogenesis. By contrast, Cx45 showed stable gene expression levels throughout development and ubiquitous immunoreactivity in progenitor cells. From later embryonic development, Cx45 was mainly observed in the inner retina, and it was expressed by glial cells and neurons. In turn, Cx50 was virtually absent in the chick retina at initial embryonic phases. Combination of PCR, immunohistochemistry and Western blot indicated that this Cx was present in differentiated cells, arising in parallel with the formation of the visual circuitry. Characterization of Cx expression in the developing chick retina indicated particular roles for these proteins and revealed similarities and differences when compared to other species.
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Affiliation(s)
- A H Kihara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil.
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36
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Kihara AH, Paschon V, Cardoso CM, Higa GSV, Castro LM, Hamassaki DE, Britto LRG. Connexin36, an essential element in the rod pathway, is highly expressed in the essentially rodless retina of Gallus gallus. J Comp Neurol 2009; 512:651-63. [PMID: 19051319 DOI: 10.1002/cne.21920] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Electrical coupling provided by connexins (Cx) in gap junctions (GJ) plays important roles in both the developing and the mature retina. In mammalian nocturnal species, Cx36 is an essential component in the rod pathway, the retinal circuit specialized for night, scotopic vision. Here, we report the expression of Cx36 in a species (Gallus gallus) that phylogenetic development endows with an essentially rodless retina. Cx36 gene is very highly expressed in comparison with other Cxs previously described in the adult retina, such as Cx43, Cx45, and Cx50. Moreover, real-time PCR, Western blot, and immunofluorescence all revealed that Cx36 expression massively increased over time during development. We thoroughly examined Cx36 in the inner and outer plexiform layers, where this protein was particularly abundant. Cx36 was observed mainly in the off sublamina of the inner plexiform layer rather than in the on sublamina previously described in the mammalian retina. In addition, Cx36 colocalized with specific cell markers, revealing the expression of this protein in distinct amacrine cells. To investigate further the involvement of Cx36 in visual processing, we examined its functional regulation in retinas from dark-adapted animals. Light deprivation markedly up-regulates Cx36 gene expression in the retina, resulting in an increased accumulation of the protein within and between cone synaptic terminals. In summary, the developmental regulation of Cx36 expression results in particular circuitry-related roles in the chick retina. Moreover, this study demonstrated that Cx36 onto- and phylogenesis in the vertebrate retina simultaneously exhibit similarities and particularities.
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Affiliation(s)
- A H Kihara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
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Yu D, Buibas M, Chow SK, Lee IY, Singer Z, Silva GA. Characterization of Calcium-Mediated Intracellular and Intercellular Signaling in the rMC-1 Glial Cell Line. Cell Mol Bioeng 2008; 2:144-155. [PMID: 19890481 DOI: 10.1007/s12195-008-0039-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Retinal Müller glial cells, in addition to providing homeostatic support to retinal neurons, have been shown to engage in modulation of neuronal activity and regulate vasomotor responses in the retina, among other functions. Calcium-mediated signaling in Müller cells has been implicated to play a significant role in the intracellular and intercellular interactions necessary to carry out these functions. Although the basic molecular mechanisms of calcium signaling in Müller cells have been described, the dynamics of calcium responses in Müller cells have not been fully explored. Here, we provide a quantitative characterization of calcium signaling in an in vitro model of Müller cell signaling using the rMC-1 cell line, a well-established line developed from rat Müller cells. rMC-1 cells displayed robust intracellular calcium transients and the capacity to support calcium transient-mediated intercellular calcium waves with signaling dynamics similar to that reported for Müller cells in in situ retinal preparations. Furthermore, pharmacological perturbations of intracellular calcium transients with thapsigargin and intercellular calcium waves with purinergic receptor antagonists and gap junction blockers (PPADS and FFA, respectively) suggest that the molecular mechanisms that underlie calcium signaling in rMC-1 cells has been conserved with those of Müller cells. This model provides a robust in vitro system for investigating specific mechanistic hypotheses of intra- and intercellular calcium signaling in Müller cells.
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Affiliation(s)
- Diana Yu
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
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Horowitz SS, Stamper SA, Simmons JA. Neuronal connexin expression in the cochlear nucleus of big brown bats. Brain Res 2008; 1197:76-84. [PMID: 18241843 DOI: 10.1016/j.brainres.2007.12.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 12/12/2007] [Accepted: 12/13/2007] [Indexed: 11/26/2022]
Abstract
We present immunohistochemical data describing the presence and distribution of connexins, structural component of gap junctions, in the cochlear nuclei of adult big brown bats (Eptesicus fuscus). Echolocating big brown bats show microsecond scale echo-delay sensitivity that requires accurate synchronization of neuronal responses to the timing of echoes. Midbrain and auditory cortical neuronal response timing is similar to that observed in other non-echolocating mammals, suggesting that lower auditory processing nuclei may have specialized mechanisms for obtaining the required temporal hyperacuity. Our data shows that connexin 36, a gap junction protein specific to neurons, is most densely expressed in the bat's cochlear nuclear complex, the medullary region that receives and processes first-order afferents from the auditory nerve. Cx36 expression is absent in the cochlear nucleus of normal mice, which have high-frequency hearing sensitivity similar to big brown bats. Glial connexins, Cx26 and Cx43, expressed in astrocytes and several inner ear structures, are also found in the bat cochlear nucleus complex, associated with major fiber tracts in and around the cochlear nuclei. The extensive presence of neuronally-associated Cx36 in brainstem auditory structures of adult bats suggests a possible role for gap junctions in mediating echo-delay hyperacuity.
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Affiliation(s)
- Seth S Horowitz
- Psychology Department, Brown University, Box 1853, Providence RI 02912, USA.
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Fu Q, Lv JJ, Zhang H. Effects of chronic renal failure on the expression of connexin 43 in the rat's corpus cavernosum. Asian J Androl 2007; 10:286-9. [PMID: 18097526 DOI: 10.1111/j.1745-7262.2008.00334.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
AIM To explore the mechanism of chronic renal failure (CRF)-related erectile dysfunction (ED). METHODS CRF experimental models were established by 5/6 nephrectomy from male Sprague-Dawley rats. Both the rats from the control group (NCRF group, n=6) and the experimental group (CRF group, n=30) were injected with a low dose (80 microg/kg) of apomorphine in the 12th week after resection surgery to measure corresponding penile erections. Western blot method was thereafter conducted to measure the expression of connexin 43 (CX43) in the rat corpus cavernosum in the 12th week after the resection surgery. RESULTS There was one death in the NCRF group and five in the CRF group. The penile erection ratio of the CRF group was 28% (7/25), whereas that of the NCRF group was 100% (5/5), which presents a significant difference between the two groups (P < 0.05). In terms of penile erection frequency, the average of the CRF group was 1.0 +/- 0.0, which was significantly different from that of the NCRF group (2.2 +/- 0.8) (P < 0.05). As for the expression of CX43 in the rat corpus cavernosum, a notable difference existed between the CRF group (0.21 +/- 0.07) and the NCRF group (0.53 +/- 0.27) (P < 0.01). CONCLUSION CRF significantly reduces the erectile function of rats. A close correlation exists between the expression of CX43 in rats' corpus cavernosum and CRF-related ED.
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Affiliation(s)
- Qiang Fu
- Department of Urology, Shandong Provincial Hospital, Shandong University, 324 Jingwu Road, Jinan, China.
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Kihara AH, Santos TO, Paschon V, Matos RJB, Britto LRG. Lack of photoreceptor signaling alters the expression of specific synaptic proteins in the retina. Neuroscience 2007; 151:995-1005. [PMID: 18248909 DOI: 10.1016/j.neuroscience.2007.09.088] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/28/2007] [Accepted: 12/18/2007] [Indexed: 11/17/2022]
Abstract
Synaptic modulation by activity-dependent changes constitutes a cellular mechanism for neuronal plasticity. However, it is not clear how the complete lack of neuronal signaling specifically affects elements involved in the communication between neurons. In the retina, it is now well established that both chemical and electrical synapses are essential to mediate the transmission of visual signaling triggered by the photoreceptors. In this study, we compared the expression of synaptic proteins in the retinas of wild-type (WT) vs. rd/rd mice, an animal model that displays inherited and specific ablation of photoreceptors caused by a mutation in the gene encoding the beta-subunit of rod cGMP-phosphodiesterase (Pde6brd1). We specifically examined the expression of connexins (Cx), the proteins that form the gap junction channels of electrical synapses, in addition to synaptophysin and synapsin I, which are involved in the release of neurotransmitters at chemical synapses. Our results revealed that Cx36 gene expression levels are lower in the retinas of rd/rd when compared with WT. Confocal analysis indicated that Cx36 immunolabeling almost disappeared in the outer plexiform layer without significant changes in protein distribution within the inner plexiform layer of rd/rd retinas. Likewise, synaptophysin expression remarkably decreased in the outer plexiform layer of rd/rd retinas, and this down-regulation was also associated with diminished transcript levels. Furthermore, we observed down-regulation of Cx57 gene expression in rd/rd retinas when compared with WT and also changes in protein distribution. Interestingly, Cx45 and synapsin I expression in rd/rd retinas showed no noticeable changes when compared with WT. Taken together, our results revealed that the loss of photoreceptors leads to decreased expression of some synaptic proteins. More importantly, this study provides evidence that neuronal activity regulates, but is not essential to maintain, the expression of synaptic elements.
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Affiliation(s)
- A H Kihara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, 05508-900, São Paulo, SP, Brazil.
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