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Bastola T, Perkins GA, Kim KY, Choi S, Kwon JW, Shen Z, Strack S, Ju WK. Role of A-Kinase Anchoring Protein 1 in Retinal Ganglion Cells: Neurodegeneration and Neuroprotection. Cells 2023; 12:1539. [PMID: 37296658 PMCID: PMC10252895 DOI: 10.3390/cells12111539] [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: 03/25/2023] [Revised: 05/21/2023] [Accepted: 06/01/2023] [Indexed: 06/12/2023] Open
Abstract
A-Kinase anchoring protein 1 (AKAP1) is a multifunctional mitochondrial scaffold protein that regulates mitochondrial dynamics, bioenergetics, and calcium homeostasis by anchoring several proteins, including protein kinase A, to the outer mitochondrial membrane. Glaucoma is a complex, multifactorial disease characterized by a slow and progressive degeneration of the optic nerve and retinal ganglion cells (RGCs), ultimately resulting in vision loss. Impairment of the mitochondrial network and function is linked to glaucomatous neurodegeneration. Loss of AKAP1 induces dynamin-related protein 1 dephosphorylation-mediated mitochondrial fragmentation and loss of RGCs. Elevated intraocular pressure triggers a significant reduction in AKAP1 protein expression in the glaucomatous retina. Amplification of AKAP1 expression protects RGCs from oxidative stress. Hence, modulation of AKAP1 could be considered a potential therapeutic target for neuroprotective intervention in glaucoma and other mitochondria-associated optic neuropathies. This review covers the current research on the role of AKAP1 in the maintenance of mitochondrial dynamics, bioenergetics, and mitophagy in RGCs and provides a scientific basis to identify and develop new therapeutic strategies that could protect RGCs and their axons in glaucoma.
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Affiliation(s)
- Tonking Bastola
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093, USA; (T.B.); (S.C.); (J.-W.K.); (Z.S.)
| | - Guy A. Perkins
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA; (G.A.P.); (K.-Y.K.)
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA; (G.A.P.); (K.-Y.K.)
| | - Seunghwan Choi
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093, USA; (T.B.); (S.C.); (J.-W.K.); (Z.S.)
| | - Jin-Woo Kwon
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093, USA; (T.B.); (S.C.); (J.-W.K.); (Z.S.)
- Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
- Department of Ophthalmology and Visual Science, St. Vincent’s Hospital, Jungbu-daero 93, Paldal-gu, Suwon 16247, Republic of Korea
| | - Ziyao Shen
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093, USA; (T.B.); (S.C.); (J.-W.K.); (Z.S.)
| | - Stefan Strack
- Department of Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA;
| | - Won-Kyu Ju
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093, USA; (T.B.); (S.C.); (J.-W.K.); (Z.S.)
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2
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Miao Y, Zhao GL, Cheng S, Wang Z, Yang XL. Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma. Prog Retin Eye Res 2023; 93:101169. [PMID: 36736070 DOI: 10.1016/j.preteyeres.2023.101169] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/12/2023] [Accepted: 01/24/2023] [Indexed: 02/04/2023]
Abstract
Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.
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Affiliation(s)
- Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
| | - Xiong-Li Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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3
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Wu HJ, Li XY, Qian WJ, Li Q, Wang SY, Ji M, Ma YY, Gao F, Sun XH, Wang X, Miao Y, Yang XL, Wang Z. Dopamine D1 receptor-mediated upregulation of BKCa
currents modifies Müller cell gliosis in a rat chronic ocular hypertension model. Glia 2018; 66:1507-1519. [PMID: 29508439 DOI: 10.1002/glia.23321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Hang-Jing Wu
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Xue-Yan Li
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Wen-Jing Qian
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Qian Li
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Shu-Yue Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Min Ji
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Yuan-Yuan Ma
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Feng Gao
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Xing-Huai Sun
- Department of Ophthalmology at Eye & ENT Hospital; Fudan University; Shanghai 200031 China
| | - Xin Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Yanying Miao
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Xiong-Li Yang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
| | - Zhongfeng Wang
- Department of Neurology; Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, Zhongshan Hospital, Fudan University; Shanghai 200032 China
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Abstract
Retinal Müller glial cells have been shown to undergo reactive gliosis in a variety of retinal diseases. Upregulation of glial fibrillary acidic protein (GFAP) is a hallmark of Müller cell activation. Reactive gliosis after retinal detachment or ischemia/reperfusion is characterized by hypertrophy and downregulation of inwardly rectifying K+ (Kir) currents. However, this kind of physiological alteration could not be detected in slowly progressing retinal degenerations. The photoreceptor toxin N-methyl-N-nitrosourea (MNU) leads to the rapid loss of cells in the outer nuclear layer and subsequent Müller cell activation. Here, we investigated whether Müller cells from MNU-treated mice exhibit reactive gliosis. We found that Müller cells showed increased GFAP expression and increased membrane capacitance, indicating hypertrophy. Membrane potential and Kir channel-mediated K+ currents were not significantly altered whereas Kir4.1 mRNA expression and Kir-mediated inward current densities were markedly decreased. This suggests that MNU-induced Müller cell gliosis is characterized by plasma membrane increase without alteration in the membrane content of Kir channels. Taken together, our findings show that Müller cells of MNU-treated mice are reactive and respond with a form of gliosis which is characterized by cellular hypertrophy but no changes in Kir current amplitudes.
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Joachim SC, Renner M, Reinhard J, Theiss C, May C, Lohmann S, Reinehr S, Stute G, Faissner A, Marcus K, Dick HB. Protective effects on the retina after ranibizumab treatment in an ischemia model. PLoS One 2017; 12:e0182407. [PMID: 28800629 PMCID: PMC5553852 DOI: 10.1371/journal.pone.0182407] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/18/2017] [Indexed: 12/13/2022] Open
Abstract
Retinal ischemia is common in eye disorders, like diabetic retinopathy or retinal vascular occlusion. The goal of this study was to evaluate the potential protective effects of an intravitreally injected vascular endothelial growth factor (VEGF) inhibitor (ranibizumab) on retinal cells in an ischemia animal model via immunohistochemistry (IF) and quantitative real-time PCR (PCR). A positive binding of ranibizumab to rat VEGF-A was confirmed via dot blot. One eye underwent ischemia and a subgroup received ranibizumab. A significant VEGF increase was detected in aqueous humor of ischemic eyes (p = 0.032), whereas VEGF levels were low in ranibizumab eyes (p = 0.99). Ischemic retinas showed a significantly lower retinal ganglion cell number (RGC; IF Brn-3a: p<0.001, IF RBPMS: p<0.001; PCR: p = 0.002). The ranibizumab group displayed fewer RGCs (IF Brn-3a: 0.3, IF RBPMS: p<0.001; PCR: p = 0.007), but more than the ischemia group (IF Brn-3a: p = 0.04, IF RBPMS: p = 0.03). Photoreceptor area was decreased after ischemia (IF: p = 0.049; PCR: p = 0.511), while the ranibizumab group (IF: p = 0.947; PCR: p = 0.122) was comparable to controls. In the ischemia (p<0.001) and ranibizumab group (p<0.001) a decrease of ChAT+ amacrine cells was found, which was less prominent in the ranibizumab group. VEGF-receptor 2 (VEGF-R2; IF: p<0.001; PCR: p = 0.021) and macroglia (GFAP; IF: p<0.001; PCR: p<0.001) activation was present in ischemic retinas. The activation was weaker in ranibizumab retinas (VEGF-R2: IF: p = 0.1; PCR: p = 0.03; GFAP: IF: p = 0.1; PCR: p = 0.015). An increase in the number of total (IF: p = 0.003; PCR: p = 0.023) and activated microglia (IF: p<0.001; PCR: p = 0.009) was detected after ischemia. These levels were higher in the ranibizumab group (Iba1: IF: p<0.001; PCR: p = 0.018; CD68: IF: p<0.001; PCR: p = 0.004). Our findings demonstrate that photoreceptors and RGCs are protected by ranibizumab treatment. Only amacrine cells cannot be rescued. They seem to be particularly sensitive to ischemic damage and need maybe an earlier intervention.
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Affiliation(s)
- Stephanie C. Joachim
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
- * E-mail:
| | - Marina Renner
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
| | - Jacqueline Reinhard
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Carsten Theiss
- Department of Cytology, Faculty of Medicine, Ruhr-University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Caroline May
- Medizinisches Proteom-Center, Ruhr-University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Stephanie Lohmann
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
| | - Sabrina Reinehr
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
| | - Gesa Stute
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Katrin Marcus
- Medizinisches Proteom-Center, Ruhr-University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - H. Burkhard Dick
- Experimental Eye Research, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23–25, Bochum, Germany
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Minhas G, Sharma J, Khan N. Cellular Stress Response and Immune Signaling in Retinal Ischemia-Reperfusion Injury. Front Immunol 2016; 7:444. [PMID: 27822213 PMCID: PMC5075763 DOI: 10.3389/fimmu.2016.00444] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/07/2016] [Indexed: 01/04/2023] Open
Abstract
Ischemia–reperfusion injury is a well-known pathological hallmark associated with diabetic retinopathy, glaucoma, and other related retinopathies that ultimately can lead to visual impairment and vision loss. Retinal ischemia pathogenesis involves a cascade of detrimental events that include energy failure, excitotoxic damage, calcium imbalance, oxidative stress, and eventually cell death. Retina for a long time has been known to be an immune privileged site; however, recent investigations reveal that retina, as well as the central nervous system, elicits immunological responses during various stress cues. Stress condition, such as reperfusion of blood supply post-ischemia results in the sequestration of different immune cells, inflammatory mediators including cytokines, chemokines, etc., to the ischemic region, which in turn facilitates induction of inflammatory conditions in these tissues. The immunological activation during injury or stress per se is beneficial for repair and maintenance of cellular homeostasis, but whether the associated inflammation is good or bad, during ischemia–reperfusion injury, hitherto remains to be explored. Keeping all these notions in mind, the current review tries to address the immune response and host stress response mechanisms involved in ischemia–reperfusion injury with the focus on the retina.
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Affiliation(s)
- Gillipsie Minhas
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad , Hyderabad , Telangana, India
| | - Jyoti Sharma
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad , Hyderabad , Telangana, India
| | - Nooruddin Khan
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad , Hyderabad , Telangana, India
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7
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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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Endothelins Inhibit Osmotic Swelling of Rat Retinal Glial and Bipolar Cells by Activation of Growth Factor Signaling. Neurochem Res 2016; 41:2598-2606. [PMID: 27278757 DOI: 10.1007/s11064-016-1971-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 12/23/2022]
Abstract
Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Here, we show that endothelin-1 (ET-1) dose-dependently inhibits the hypoosmotic swelling of Müller cells in freshly isolated retinal slices of control and diabetic rats, with a maximal inhibition at 100 nM. Osmotic Müller cell swelling was also inhibited by ET-2. The effect of ET-1 was mediated by activation of ETA and ETB receptors resulting in transactivation of metabotropic glutamate receptors, purinergic P2Y1, and adenosine A1 receptors. ET-1 (but not ET-2) also inhibited the osmotic swelling of bipolar cells in retinal slices, but failed to inhibit the swelling of freshly isolated bipolar cells. The inhibitory effect of ET-1 on the bipolar cell swelling in retinal slices was abrogated by inhibitors of the FGF receptor kinase (PD173074) and of TGF-β1 superfamily activin receptor-like kinase receptors (SB431542), respectively. Both Müller and bipolar cells displayed immunoreactivities of ETA and ETB receptor proteins. The data may suggest that neuroprotective effects of ETs in the retina are in part mediated by prevention of the cytotoxic swelling of retinal glial and bipolar cells. ET-1 acts directly on Müller cells, while the inhibitory effect of ET-1 on bipolar cell swelling is indirectly mediated, via stimulation of the release of growth factors like bFGF and TGF-β1 from Müller cells.
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Vogler S, Winters H, Pannicke T, Wiedemann P, Reichenbach A, Bringmann A. Sigma-1 receptor activation inhibits osmotic swelling of rat retinal glial (Müller) cells by transactivation of glutamatergic and purinergic receptors. Neurosci Lett 2015; 610:13-8. [PMID: 26499958 DOI: 10.1016/j.neulet.2015.10.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/05/2015] [Accepted: 10/14/2015] [Indexed: 12/28/2022]
Abstract
Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Sigma (σ) receptor activation is known to have neuroprotective effects in the retina. Here, we show that the nonselective σ receptor agonist ditolylguanidine, and the selective σ1 receptor agonist PRE-084, inhibit the osmotic swelling of Müller cell somata induced by superfusion of rat retinal slices with a hypoosmotic solution containing barium ions. In contrast, PRE-084 did not inhibit the osmotic swelling of bipolar cell somata. The effects of σ receptor agonists on the Müller cell swelling were abrogated in the presence of blockers of metabotropic glutamate and purinergic P2Y1 receptors, respectively, suggesting that σ receptor activation triggers activation of a glutamatergic-purinergic signaling cascade which is known to prevent the osmotic Müller cell swelling. The swelling-inhibitory effect of 17β-estradiol was prevented by the σ1 receptor antagonist BD1047, suggesting that the effect is mediated by σ1 receptor activation. The data may suggest that the neuroprotective effect of σ receptor activation in the retina is in part mediated by prevention of the cytotoxic swelling of retinal glial cells.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Helge Winters
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany.
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10
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Liu J, Yeung PKK, Cheng L, Lo ACY, Chung SSM, Chung SK. Epac2-deficiency leads to more severe retinal swelling, glial reactivity and oxidative stress in transient middle cerebral artery occlusion induced ischemic retinopathy. SCIENCE CHINA-LIFE SCIENCES 2015; 58:521-30. [PMID: 25985753 DOI: 10.1007/s11427-015-4860-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/13/2015] [Indexed: 01/01/2023]
Abstract
Ischemia occurs in diabetic retinopathy with neuronal loss, edema, glial cell reactivity and oxidative stress. Epacs, consisting of Epac1 and Epac2, are cAMP mediators playing important roles in maintenance of endothelial barrier and neuronal functions. To investigate the roles of Epacs in the pathogenesis of ischemic retinopathy, transient middle cerebral artery occlusion (tMCAO) was performed on Epac1-deficient (Epac1 (-/-)) mice, Epac2-deficient (Epac2 (-/-)) mice, and their wild type counterparts (Epac1 (+/+) and Epac2 (+/+)). Two-hour occlusion and 22-hour reperfusion were conducted to induce ischemia/reperfusion injury to the retina. After tMCAO, the contralateral retinae displayed similar morphology between different genotypes. Neuronal loss, retinal edema and increase in immunoreactivity for aquaporin 4 (AQP4), glial fibrillary acidic protein (GFAP), peroxiredoxin 6 (Prx6) were observed in ipsilateral retinae. Epac2 (-/-) ipsilateral retinae showed more neuronal loss in retinal ganglion cell layer, increased retinal thickness and stronger immunostaining of AQP4, GFAP, and Prx6 than those of Epac2 (+/+). However, Epac1 (-/-) ipsilateral retinae displayed similar pathology as those in Epac1 (+/+) mice. Our observations suggest that Epac2-deficiency led to more severe ischemic retinopathy after retinal ischemia/reperfusion injury.
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Affiliation(s)
- Jin Liu
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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11
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Rela L, Piantanida AP, Bordey A, Greer CA. Voltage-dependent K+ currents contribute to heterogeneity of olfactory ensheathing cells. Glia 2015; 63:1646-59. [PMID: 25856239 DOI: 10.1002/glia.22834] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 03/24/2015] [Indexed: 02/03/2023]
Abstract
The olfactory nerve is permissive for axon growth throughout life. This has been attributed in part to the olfactory ensheathing glial cells that encompass the olfactory sensory neuron fascicles. Olfactory ensheathing cells (OECs) also promote axon growth in vitro and when transplanted in vivo to sites of injury. The mechanisms involved remain largely unidentified owing in part to the limited knowledge of the physiological properties of ensheathing cells. Glial cells rely for many functions on the properties of the potassium channels expressed; however, those expressed in ensheathing cells are unknown. Here we show that OECs express voltage-dependent potassium currents compatible with inward rectifier (Kir ) and delayed rectifier (KDR ) channels. Together with gap junction coupling, these contribute to the heterogeneity of membrane properties observed in OECs. The relevance of K(+) currents expressed by ensheathing cells is discussed in relation to plasticity of the olfactory nerve.
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Affiliation(s)
- Lorena Rela
- Departments of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut.,Systems Neuroscience Section, Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, Argentina.,Institute of Physiology and Biophysics Bernardo Houssay (IFIBIO Houssay-CONICET), Buenos Aires, Argentina
| | - Ana Paula Piantanida
- Systems Neuroscience Section, Department of Physiology and Biophysics, School of Medicine, University of Buenos Aires, Argentina.,Institute of Physiology and Biophysics Bernardo Houssay (IFIBIO Houssay-CONICET), Buenos Aires, Argentina
| | - Angelique Bordey
- Departments of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut.,Yale University School of Medicine, Departments of Cellular and Molecular Physiology, New Haven, Connecticut
| | - Charles A Greer
- Departments of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut.,Yale University School of Medicine, Departments of Neurobiology, New Haven, Connecticut
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13
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Lu B, Wu X. The Protective Effect of Compound Danshen Dripping Pills on Oxidative Stress after Retinal Ischemia/Reperfusion Injury in Rats. Chin Med 2015. [DOI: 10.4236/cm.2015.62010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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Vogler S, Pannicke T, Hollborn M, Grosche A, Busch S, Hoffmann S, Wiedemann P, Reichenbach A, Hammes HP, Bringmann A. Müller cell reactivity in response to photoreceptor degeneration in rats with defective polycystin-2. PLoS One 2013; 8:e61631. [PMID: 23755094 PMCID: PMC3670868 DOI: 10.1371/journal.pone.0061631] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/12/2013] [Indexed: 12/18/2022] Open
Abstract
Background Retinal degeneration in transgenic rats that express a mutant cilia gene polycystin-2 (CMV-PKD2(1/703)HA) is characterized by initial photoreceptor degeneration and glial activation, followed by vasoregression and neuronal degeneration (Feng et al., 2009, PLoS One 4: e7328). It is unknown whether glial activation contributes to neurovascular degeneration after photoreceptor degeneration. We characterized the reactivity of Müller glial cells in retinas of rats that express defective polycystin-2. Methods Age-matched Sprague-Dawley rats served as control. Retinal slices were immunostained for intermediate filaments, the potassium channel Kir4.1, and aquaporins 1 and 4. The potassium conductance of isolated Müller cells was recorded by whole-cell patch clamping. The osmotic swelling characteristics of Müller cells were determined by superfusion of retinal slices with a hypoosmotic solution. Findings Müller cells in retinas of transgenic rats displayed upregulation of GFAP and nestin which was not observed in control cells. Whereas aquaporin-1 labeling of photoreceptor cells disappeared along with the degeneration of the cells, aquaporin-1 emerged in glial cells in the inner retina of transgenic rats. Aquaporin-4 was upregulated around degenerating photoreceptor cells. There was an age-dependent redistribution of Kir4.1 in retinas of transgenic rats, with a more even distribution along glial membranes and a downregulation of perivascular Kir4.1. Müller cells of transgenic rats displayed a slight decrease in their Kir conductance as compared to control. Müller cells in retinal tissues from transgenic rats swelled immediately under hypoosmotic stress; this was not observed in control cells. Osmotic swelling was induced by oxidative-nitrosative stress, mitochondrial dysfunction, and inflammatory lipid mediators. Interpretation Cellular swelling suggests that the rapid water transport through Müller cells in response to osmotic stress is altered as compared to control. The dislocation of Kir4.1 will disturb the retinal potassium and water homeostasis, and osmotic generation of free radicals and inflammatory lipids may contribute to neurovascular injury.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Antje Grosche
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Stephanie Busch
- 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Sigrid Hoffmann
- Medical Research Center, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Hans-Peter Hammes
- 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
- * E-mail:
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Munemasa Y, Kitaoka Y. Molecular mechanisms of retinal ganglion cell degeneration in glaucoma and future prospects for cell body and axonal protection. Front Cell Neurosci 2013; 6:60. [PMID: 23316132 PMCID: PMC3540394 DOI: 10.3389/fncel.2012.00060] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 12/06/2012] [Indexed: 12/20/2022] Open
Abstract
Glaucoma, which affects more than 70 million people worldwide, is a heterogeneous group of disorders with a resultant common denominator; optic neuropathy, eventually leading to irreversible blindness. The clinical manifestations of primary open-angle glaucoma (POAG), the most common subtype of glaucoma, include excavation of the optic disc and progressive loss of visual field. Axonal degeneration of retinal ganglion cells (RGCs) and apoptotic death of their cell bodies are observed in glaucoma, in which the reduction of intraocular pressure (IOP) is known to slow progression of the disease. A pattern of localized retinal nerve fiber layer (RNFL) defects in glaucoma patients indicates that axonal degeneration may precede RGC body death in this condition. The mechanisms of degeneration of neuronal cell bodies and their axons may differ. In this review, we addressed the molecular mechanisms of cell body death and axonal degeneration in glaucoma and proposed axonal protection in addition to cell body protection. The concept of axonal protection may become a new therapeutic strategy to prevent further axonal degeneration or revive dying axons in patients with preperimetric glaucoma. Further study will be needed to clarify whether the combination therapy of axonal protection and cell body protection will have greater protective effects in early or progressive glaucomatous optic neuropathy (GON).
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Affiliation(s)
- Yasunari Munemasa
- Department of Ophthalmology, St. Marianna University School of Medicine Kawasaki, Kanagawa, Japan
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16
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Bringmann A, Grosche A, Pannicke T, Reichenbach A. GABA and Glutamate Uptake and Metabolism in Retinal Glial (Müller) Cells. Front Endocrinol (Lausanne) 2013; 4:48. [PMID: 23616782 PMCID: PMC3627989 DOI: 10.3389/fendo.2013.00048] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/04/2013] [Indexed: 12/11/2022] Open
Abstract
Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and γ-aminobutyric acid (GABA). Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the shaping and termination of the synaptic activity, particularly in the inner retina. Reactive Müller cells are neuroprotective, e.g., by the clearance of excess extracellular glutamate, but may also contribute to neuronal degeneration by a malfunctioning or even reversal of glial glutamate transporters, or by a downregulation of the key enzyme, glutamine synthetase. This review summarizes the present knowledge about the role of Müller cells in the clearance and metabolization of extracellular glutamate and GABA. Some major pathways of GABA and glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Antje Grosche
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of LeipzigLeipzig, Germany
- *Correspondence: Andreas Reichenbach, Paul Flechsig Institute of Brain Research, University of Leipzig, Jahnallee 59, D-04109 Leipzig, Germany. e-mail:
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17
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Slezak M, Grosche A, Niemiec A, Tanimoto N, Pannicke T, Münch T, Crocker B, Isope P, Härtig W, Beck S, Huber G, Ferracci G, Perraut M, Reber M, Miehe M, Demais V, Lévêque C, Metzger D, Szklarczyk K, Przewlocki R, Seeliger M, Sage-Ciocca D, Hirrlinger J, Reichenbach A, Reibel S, Pfrieger F. Relevance of Exocytotic Glutamate Release from Retinal Glia. Neuron 2012; 74:504-16. [DOI: 10.1016/j.neuron.2012.03.027] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2012] [Indexed: 10/28/2022]
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18
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Yan J, Khatibi NH, Han H, Hu Q, Chen C, Li L, Yang X, Zhou C. p53-induced uncoupling expression of aquaporin-4 and inwardly rectifying K+ 4.1 channels in cytotoxic edema after subarachnoid hemorrhage. CNS Neurosci Ther 2012; 18:334-42. [PMID: 22420318 PMCID: PMC6493666 DOI: 10.1111/j.1755-5949.2012.00299.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 11/28/2011] [Accepted: 12/16/2011] [Indexed: 11/30/2022] Open
Abstract
AIMS To investigate the mechanism behind cytotoxic edema formation following subarachnoid hemorrhage (SAH). METHODS We explored the role of aquaporin-4 (AQP4), inwardly rectifying K(+) 4.1 (Kir4.1) channels and their upstream orchestrators p53 and p38MAPK in this process. A p53 inhibitor, pifithrin-α (PFT-α) was administered intraperitoneally to rats undergoing SAH by endovascular perforation. Totally, 98 male SD rats were categorized into sham, SAH, SAH+ dimethyl sulfoxide (DMSO), SAH+ 0.2 or 2.0 mg/kg PFT-α groups. At 24 h after SAH, MRI (diffusion-weighted imaging [DWI]), immunohistochemistry, and Western blot were used. RESULTS MRI (DWI) showed a significant cytotoxic edema in the brain following SAH with PFT-α therapy reducing it. Immunohistochemistry and Western blot showed an increased level of p53, phosphorylated-p38MAPK and AQP4 and a reduced level of Kir4.1; all of which could be reversed following PFT-α treatment. Treble labeling staining revealed colocalization of p53 with phosphorylated-p38MAPK and unmatched expression of AQP4 and Kir4.1 within astrocyte cells. CONCLUSION These results indicated p53 mediates the formation of cytotoxic edema in the brain following SAH; an uncoupling expression of AQP4 and Kir4.1 on astrocytic end feet orchestrated by p38MAPK was partly responsible.
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Affiliation(s)
- Jun‐hao Yan
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China
- Department of Physiology and Pharmacology, Loma Linda University, Medical Center, Loma Linda, California
| | - Nikan H. Khatibi
- Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, California
| | - Hong‐bin Han
- Department of Radiology, Peking University Third Hospital, Beijing, China
| | - Qin Hu
- Department of Physiology and Pharmacology, Loma Linda University, Medical Center, Loma Linda, California
| | - Chun‐hua Chen
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China
- Department of Physiology and Pharmacology, Loma Linda University, Medical Center, Loma Linda, California
| | - Li Li
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Xiao‐mei Yang
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Chang‐man Zhou
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China
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Chavira-Suárez E, Sandoval A, Quintero H, Bustamante P, Felix R, Lamas M. Hyperglycemia induces early upregulation of the calcium sensor KChIP3/DREAM/calsenilin in the rat retina. Biochem Biophys Res Commun 2012; 418:420-5. [PMID: 22277672 DOI: 10.1016/j.bbrc.2012.01.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 01/10/2012] [Indexed: 11/18/2022]
Abstract
Hyperglycemia alters the tight control of intracellular calcium dynamics in retinal cells and may lead to the development of diabetic retinopathy. The potassium channel interacting protein 3 (KChIP3) also known as DREAM (Downstream Regulatory Element Antagonist Modulator) or calsenilin (KChIP3/DREAM/calsenilin), a member of the neuronal calcium sensor protein family, is expressed in Müller glial cells and upregulated under high glucose experimental culture conditions. Here, we analyzed the expression and function of KChIP3 in the retina of streptozotocin induced diabetic Long Evans rats by immunofluorescence confocal microscopy, western blot, co-immunoprecipitation, whole cell patch clamp recording on isolated cells and KChIP3 gene silencing by RNA interference. Three weeks after streptozotocin application, KChIP3 was increased throughout the different retinal layers and this process was not linked to augmented apoptosis. KChIP3 co-immunoprecipitated with voltage gated K(+) channels of the K(V)4.2-4.3 subtype in retinal extracts from control and hyperglycemic rats. Electrophysiological analysis showed that control cells did not express A type (K(V)4-mediated) K(+) currents but most of the cells from streptozotocin treated retinas displayed macroscopic currents with an inactivating component sensitive to 4-AP, suggesting the persistence of the A type currents at early times after treatment. siRNA analysis in Müller cells cultures grown under high glucose experimental conditions corroborated that, when the expression of KChIP3 is 50% reduced, the number of cells expressing A type currents decreases significantly. Together these data suggest an altered expression and function of KChIP3 after streptozotocin induced hyperglycemia that might help explain some pathological alterations in early diabetic retinopathy.
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Affiliation(s)
- Erika Chavira-Suárez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN (Cinvestav-IPN), Mexico Distrito Federal, Mexico
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Selective over-expression of endothelin-1 in endothelial cells exacerbates inner retinal edema and neuronal death in ischemic retina. PLoS One 2011; 6:e26184. [PMID: 22053184 PMCID: PMC3203861 DOI: 10.1371/journal.pone.0026184] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 09/22/2011] [Indexed: 11/19/2022] Open
Abstract
The level of endothelin-1 (ET-1), a potent vasoconstrictor, was associated with retinopathy under ischemia. The effects of endothelial endothelin-1 (ET-1) over-expression in a transgenic mouse model using Tie-1 promoter (TET-1 mice) on pathophysiological changes of retinal ischemia were investigated by intraluminal insertion of a microfilament up to middle cerebral artery (MCA) to transiently block the ophthalmic artery. Two-hour occlusion and twenty-two-hour reperfusion were performed in homozygous (Hm) TET-1 mice and their non-transgenic (NTg) littermates. Presence of pyknotic nuclei in ganglion cell layer (GCL) was investigated in paraffin sections of ipsilateral (ischemic) and contralateral (non-ischemic) retinae, followed by measurement of the thickness of inner retinal layer. Moreover, immunocytochemistry of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS) and aquaporin-4 (AQP4) peptides on retinal sections were performed to study glial cell reactivity, glutamate metabolism and water accumulation, respectively after retinal ischemia. Similar morphology was observed in the contralateral retinae of NTg and Hm TET-1 mice, whereas ipsilateral retina of NTg mice showed slight structural and cellular changes compared with the corresponding contralateral retina. Ipsilateral retinae of Hm TET-1 mice showed more significant changes when compared with ipsilateral retina of NTg mice, including more prominent cell death in GCL characterized by the presence of pyknotic nuclei, elevated GS immunoreactivity in Müller cell bodies and processes, increased AQP-4 immunoreactivity in Müller cell processes, and increased inner retinal thickness. Thus, over-expression of endothelial ET-1 in TET-1 mice may contribute to increased glutamate-induced neurotoxicity on neuronal cells and water accumulation in inner retina leading to edema.
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21
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Bringmann A, Wiedemann P. Müller glial cells in retinal disease. ACTA ACUST UNITED AC 2011; 227:1-19. [PMID: 21921569 DOI: 10.1159/000328979] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 04/27/2011] [Indexed: 11/19/2022]
Abstract
Virtually all pathogenic stimuli activate Müller cells. Reactive Müller cells exert protective and toxic effects on photoreceptors and neurons. They contribute to oxidative stress and glutamate toxicity due to malfunctions of glutamate uptake and glutathione synthesis. Downregulation of potassium conductance disrupts transcellular potassium and water transport, resulting in neuronal hyperexcitability and edema. Protective effects of reactive Müller cells include upregulation of adenosine 5'-triphosphate (ATP)-degrading ectoenzymes, which enhances the extracellular availability of the neuroprotectant adenosine, abrogation of the osmotic release of ATP, which might protect retinal ganglion cells from apoptosis, and the release of antioxidants and neurotrophic factors. The dedifferentiation of reactive Müller cells to progenitor-like cells might have an impact on future therapeutic approaches. A better understanding of the gliotic mechanisms will be helpful in developing efficient therapeutic strategies aiming at increased protective and regenerative properties and decreased toxicity of reactive Müller cells.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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22
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Wurm A, Pannicke T, Iandiev I, Francke M, Hollborn M, Wiedemann P, Reichenbach A, Osborne NN, Bringmann A. Purinergic signaling involved in Müller cell function in the mammalian retina. Prog Retin Eye Res 2011; 30:324-42. [DOI: 10.1016/j.preteyeres.2011.06.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/06/2011] [Accepted: 06/06/2011] [Indexed: 10/18/2022]
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Linnertz R, Wurm A, Pannicke T, Krügel K, Hollborn M, Härtig W, Iandiev I, Wiedemann P, Reichenbach A, Bringmann A. Activation of voltage-gated Na+ and Ca2+ channels is required for glutamate release from retinal glial cells implicated in cell volume regulation. Neuroscience 2011; 188:23-34. [DOI: 10.1016/j.neuroscience.2011.04.058] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 04/20/2011] [Accepted: 04/29/2011] [Indexed: 10/18/2022]
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Dibaj P, Kaiser M, Hirrlinger J, Kirchhoff F, Neusch C. Kir4.1 channels regulate swelling of astroglial processes in experimental spinal cord edema. J Neurochem 2011; 103:2620-8. [PMID: 17953658 DOI: 10.1111/j.1471-4159.2007.04979.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In glial cells, inwardly rectifying K(+) channels (Kir) control extracellular [K(+) ](o) homeostasis by uptake of K(+) from the extracellular space and release of K(+) into the microvasculature. Kir channels were also recently implicated in K(+) -associated water influx and cell swelling. We studied the time-dependent expression and functional implication of the glial Kir4.1 channel for astroglial swelling in a spinal cord edema model. In this CNS region, Kir4.1 is expressed on astrocytes from the second postnatal week on and co-localizes with aquaporin 4 (AQP4). Swelling of individual astrocytes in response to osmotic stress and to pharmacological Kir blockade were analyzed by time-lapse-two-photon laser-scanning microscopy in situ. Application of 30% hypotonic solution induced astroglial soma swelling whereas no swelling was observed on astroglial processes or endfeet. Co-application of hypotonic solution and Ba(2+) , a Kir channel blocker, induced prominent swelling of astroglial processes. In Kir4.1-/- mice, however, somatic as well as process swelling was observed upon application of 30% hypotonic solutions. No additional effect was provoked upon co-application with Ba(2+) . Our experiments show that Kir channels prevent glial process swelling under osmotic stress. The underlying Kir channel subunit that controls glial process swelling is Kir4.1, whereas changes of the glial soma are not substantially related to Kir4.1.
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Affiliation(s)
- Payam Dibaj
- Department of Neurology, Georg-August-University Göttingen, Göttingen, Germany
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25
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Obara-Michlewska M, Pannicke T, Karl A, Bringmann A, Reichenbach A, Szeliga M, Hilgier W, Wrzosek A, Szewczyk A, Albrecht J. Down-regulation of Kir4.1 in the cerebral cortex of rats with liver failure and in cultured astrocytes treated with glutamine: Implications for astrocytic dysfunction in hepatic encephalopathy. J Neurosci Res 2011; 89:2018-27. [PMID: 21538466 DOI: 10.1002/jnr.22656] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 03/04/2011] [Accepted: 03/09/2011] [Indexed: 01/08/2023]
Abstract
Brain edema in acute hepatic encephalopathy (HE) is due mainly to swelling of astrocytes. Efflux of potassium is implicated in the prevention of glial swelling under hypoosmotic conditions. We investigated whether pathogenic factors of HE, glutamine (Gln) and/or ammonia, induce alterations in the expression of glial potassium channels (Kir4.1, Kir2.1) and Na(+) -K(+) -2Cl(-) cotransporter-1 (NKCC1) in rat cerebral cortex and cultured rat cortical astrocytes and whether these alterations have consequences for potassium efflux and astrocytic swelling. Thioacetamide-induced acute liver failure in rats resulted in significant decreases in the Kir4.1 mRNA and protein contents of cerebral cortex, whereas expression of Kir2.1 and NKCC1 remained unaltered. Incubation of primary cortical astrocytes for 72 hr in the presence of Gln (5 mM), but not of ammonia (5 mM or 10 mM), induced a decrease in the levels of Kir4.1 mRNA and protein. Similarly to incubation with Gln, reduction of Kir4.1 mRNA expression by RNA interference caused swelling of astrocytes as shown by confocal imaging followed by 3D computational analysis. Gln reduced the astrocytic uptake of D-[(3) H]aspartate, but, in contrast to the earlier reported effect of ammonia, this reduction was not accompanied by decreased expression of the astrocytic glutamate transporter GLT-1 mRNA. Both Gln and ammonia decreased hypoosmolarity-induced (86) Rb efflux from the cells, but the effect was more pronounced with Gln. The results indicate that down-regulation of Kir4.1 may mediate distinct aspects of Gln-induced astrocytic dysfunction in HE.
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Affiliation(s)
- Marta Obara-Michlewska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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26
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Hirrlinger PG, Pannicke T, Winkler U, Claudepierre T, Varshney S, Schulze C, Reichenbach A, Brunken WJ, Hirrlinger J. Genetic deletion of laminin isoforms β2 and γ3 induces a reduction in Kir4.1 and aquaporin-4 expression and function in the retina. PLoS One 2011; 6:e16106. [PMID: 21283711 PMCID: PMC3025027 DOI: 10.1371/journal.pone.0016106] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 12/07/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Glial cells such as retinal Müller glial cells are involved in potassium ion and water homeostasis of the neural tissue. In these cells, inwardly rectifying potassium (Kir) channels and aquaporin-4 water channels play an important role in the process of spatial potassium buffering and water drainage. Moreover, Kir4.1 channels are involved in the maintenance of the negative Müller cell membrane potential. The subcellular distribution of Kir4.1 and aquaporin-4 channels appears to be maintained by interactions with extracellular and intracellular molecules. Laminins in the extracellular matrix, dystroglycan in the membrane, and dystrophins in the cytomatrix form a complex mediating the polarized expression of Kir4.1 and aquaporin-4 in Müller cells. METHODOLOGY/PRINCIPAL FINDINGS The aim of the present study was to test the function of the β2 and γ3 containing laminins in murine Müller cells. We used knockout mice with genetic deletion of both β2 and γ3 laminin genes to assay the effects on Kir4.1 and aquaporin-4. We studied protein and mRNA expression by immunohistochemistry, Western Blot, and quantitative RT-PCR, respectively, and membrane currents of isolated cells by patch-clamp experiments. We found a down-regulation of mRNA and protein of Kir4.1 as well as of aquaporin-4 protein in laminin knockout mice. Moreover, Müller cells from laminin β2 and γ3 knockout mice had reduced Kir-mediated inward currents and their membrane potentials were more positive than those in age-matched wild-type mice. CONCLUSION These findings demonstrate a strong impact of laminin β2 and γ3 subunits on the expression and function of both aquaporin-4 and Kir4.1, two important membrane proteins in Müller cells.
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Affiliation(s)
- Petra G Hirrlinger
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
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Olsen ML, Campbell SC, McFerrin MB, Floyd CL, Sontheimer H. Spinal cord injury causes a wide-spread, persistent loss of Kir4.1 and glutamate transporter 1: benefit of 17 beta-oestradiol treatment. Brain 2010; 133:1013-25. [PMID: 20375134 DOI: 10.1093/brain/awq049] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
During neuronal activity astrocytes function to remove extracellular increases in potassium, which are largely mediated by the inwardly-rectifying potassium channel Kir4.1, and to take up excess glutamate via glutamate transporter 1, a glial-specific glutamate transporter. Here we demonstrate that expression of both of these proteins is reduced by nearly 80% following a crush spinal cord injury in adult male rats, 7 days post-injury. This loss extended to spinal segments several millimetres rostral and caudal to the lesion epicentre, and persisted at 4 weeks post-injury. Importantly, we demonstrate that loss of these two proteins is not a direct result of astrocyte loss, as immunohistochemistry at 7 days and western blots at 4 weeks demonstrate a marked up-regulation in glial fibrillary acidic protein expression. Kir4.1 and glutamate transporter 1 expression were partially rescued by post-spinal cord injury administration of physiological levels of 17beta-oestradiol (0.08 mg/kg/day) in vivo. Utilizing an in vitro culture system we demonstrate that 17beta-oestradiol treatment (50 nM) is sufficient to increase glutamate transporter 1 protein expression in spinal cord astrocytes. This increase in glutamate transporter 1 protein expression was reversed and Kir4.1 expression reduced in the presence of an oestrogen receptor antagonist, Fulvestrant 182,780 suggesting a direct translational regulation of Kir4.1 and glutamate transporter 1 via genomic oestrogen receptors. Using whole-cell patch-clamp recordings in cultured spinal cord astrocytes, we show that changes in protein expression following oestrogen application led to functional changes in Kir4.1 mediated currents. These findings suggest that the neuroprotective benefits previously seen with 17beta-oestradiol after spinal cord injury may be in part due to increased Kir4.1 and glutamate transporter 1 expression in astrocytes leading to improved potassium and glutamate homeostasis.
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Affiliation(s)
- Michelle L Olsen
- Department of Neurobiology, Centre for Glial Biology in Medicine, University of Alabama at Birmingham, 1719 6th Ave. S., CIRC 425, Birmingham, AL 35294, USA
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1082] [Impact Index Per Article: 77.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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Hirrlinger PG, Ulbricht E, Iandiev I, Reichenbach A, Pannicke T. Alterations in protein expression and membrane properties during Müller cell gliosis in a murine model of transient retinal ischemia. Neurosci Lett 2010; 472:73-8. [PMID: 20132867 DOI: 10.1016/j.neulet.2010.01.062] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 01/06/2010] [Accepted: 01/27/2010] [Indexed: 01/26/2023]
Abstract
Retinal Müller glial cells are involved in K+ ion homeostasis of the tissue. Inwardly rectifying K(+) (Kir) channels play a decisive role in the process of spatial K+ buffering. It has been demonstrated that Kir-mediated currents of Müller cells are downregulated in various cases of retinal neurodegeneration. However, this has not yet been verified for any murine animal model. The aim of the present study was to investigate Müller cells after transient retinal ischemia in mice. High intraocular pressure was applied for 1h; the retina was analysed 1 week later. We studied protein expression in the tissue by immunohistochemistry, and membrane currents of isolated cells by patch-clamp experiments. We found the typical indicators of reactive gliosis such as upregulation of glial fibrillary acidic protein. Moreover, the membrane capacitance of isolated Müller cells was increased and the amplitudes of Kir-mediated currents were slightly, but significantly decreased. This murine high intraocular pressure model of transient retinal ischemia is proposed as a versatile tool for further studies on Müller cell functions in retinal degeneration.
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Affiliation(s)
- Petra G Hirrlinger
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Jahnallee 59, D-04109 Leipzig, Germany
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Effect of PBNA on the NO content and NOS activity in ischemia/reperfusion injury in the rat retina. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 664:501-7. [PMID: 20238052 DOI: 10.1007/978-1-4419-1399-9_57] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To investigated the effect of Polygonum Bistorta L. n-butyl Alcohol (PBNA) extract on the NO content and NOS activity in ischemia/reperfusion (I/R) injury in the rat retina. METHODS The model of retinal I/R injury in SD rats was made by reperfusion for 1 h after occlusion of common carotid artery (CCA) for 1 h. The rats were randomly divided into four groups: control group, retinal I/R injury group, low-dosage PBNA treated group and high-dosage treated PBNA group. The control group was injected with 1 ml/kg NS through sublingual vein after CCA was dissociated. Other groups were treated with normal saline or PBNA before occlusion of CCA. After occlusion of CCA for 1 h following reperfusion for 1 h, blood was collected and serum was separated to determine the contents of NO, the activity of T-NOS, iNOS and eNOS. RESULT (1) The contents of NO in I/R group showed lower values than in control group (P<0.001) and low-dosage PBNA treated group (P<0.05). (2) The activities of T-NOS in both low-dosage PBNA group and high-dosage group increased, compared with I/R group (P<0.01). (3) The activity of serum iNOS in I/R group increased compared with control group (P<0.05) and low-dosage PBNA treated group evidently (P<0.05). (4) The activity of serum eNOS in I/R group decreased compared with control group (P<0.05), both low-dosage (P<0.05) and high-dosage PBNA (P<0.01) treated group markedly. CONCLUSION The date suggest that PBNA have a therapeutic effect on retinal ischemia/reperfusion injury by increasing the activities of T-NOS and eNOS, decreasing the activity of iNOS, elevating the content of NO, enhancing the Anti-oxidation and expanding the blood vessel.
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Zhihua H, Liangdong L, Xiao L, Fang C, Jing Z. Effect of 3′-Daidzein Sulfonic Sodium on the Anti-oxidation of Retinal Ischemia/Reperfusion Injury in Rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 664:585-91. [DOI: 10.1007/978-1-4419-1399-9_67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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Sene A, Tadayoni R, Pannicke T, Wurm A, El Mathari B, Benard R, Roux MJ, Yaffe D, Mornet D, Reichenbach A, Sahel JA, Rendon A. Functional implication of Dp71 in osmoregulation and vascular permeability of the retina. PLoS One 2009; 4:e7329. [PMID: 19809515 PMCID: PMC2754330 DOI: 10.1371/journal.pone.0007329] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Accepted: 09/11/2009] [Indexed: 11/18/2022] Open
Abstract
Functional alterations of Müller cells, the principal glia of the retina, are an early hallmark of most retina diseases and contribute to their further progression. The molecular mechanisms of these reactive Müller cell alterations, resulting in disturbed retinal homeostasis, remain largely unknown. Here we show that experimental detachment of mouse retina induces mislocation of the inwardly rectifying potassium channels (Kir4.1) and a downregulation of the water channel protein (AQP4) in Müller cells. These alterations are associated with a strong decrease of Dp71, a cytoskeleton protein responsible for the localization and the clustering of Kir4.1 and AQP4. Partial (in detached retinas) or total depletion of Dp71 in Müller cells (in Dp71-null mice) impairs the capability of volume regulation of Müller cells under osmotic stress. The abnormal swelling of Müller cells In Dp71-null mice involves the action of inflammatory mediators. Moreover, we investigated whether the alterations in Müller cells of Dp71-null mice may interfere with their regulatory effect on the blood-retina barrier. In the absence of Dp71, the retinal vascular permeability was increased as compared to the controls. Our results reveal that Dp71 is crucially implicated in the maintenance of potassium homeostasis, in transmembraneous water transport, and in the Müller cell-mediated regulation of retinal vascular permeability. Furthermore, our data provide novel insights into the mechanisms of retinal homeostasis provided by Müller cells under normal and pathological conditions.
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Affiliation(s)
- Abdoulaye Sene
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
| | - Ramin Tadayoni
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, Universität Leipzig, Leipzig, Germany
| | - Antje Wurm
- Paul Flechsig Institute of Brain Research, Universität Leipzig, Leipzig, Germany
| | - Brahim El Mathari
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
| | - Romain Benard
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
| | - Michel Joseph Roux
- Institut de Biologie Moléculaire et Cellulaire, Department of Neurobiology and Genetics, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
| | - David Yaffe
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Dominique Mornet
- Institut National de la Sante et de la Recherche Médicale, ERI 25 “Muscle et Pathologies”, Université Montpellier 1, EA 4202, CHU Arnaud de Villeneuve, Montpellier, France
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Universität Leipzig, Leipzig, Germany
| | - Jose-Alain Sahel
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
- Centre Hospitalier National d'Ophtalmologie des quinze-vingts, Paris, France
| | - Alvaro Rendon
- Institut National de la Sante et de la Recherche Médicale, UMR_S 968, Institut de la Vision, Paris, France
- Université Pierre et Marie Curie-Paris6, UMR_S 968, Paris, France
- * E-mail:
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Bringmann A, Iandiev I, Pannicke T, Wurm A, Hollborn M, Wiedemann P, Osborne NN, Reichenbach A. Cellular signaling and factors involved in Müller cell gliosis: neuroprotective and detrimental effects. Prog Retin Eye Res 2009; 28:423-51. [PMID: 19660572 DOI: 10.1016/j.preteyeres.2009.07.001] [Citation(s) in RCA: 515] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Müller cells are active players in normal retinal function and in virtually all forms of retinal injury and disease. Reactive Müller cells protect the tissue from further damage and preserve tissue function by the release of antioxidants and neurotrophic factors, and may contribute to retinal regeneration by the generation of neural progenitor/stem cells. However, Müller cell gliosis can also contribute to neurodegeneration and impedes regenerative processes in the retinal tissue by the formation of glial scars. This article provides an overview of the neuroprotective and detrimental effects of Müller cell gliosis, with accounts on the cellular signal transduction mechanisms and factors which are implicated in Müller cell-mediated neuroprotection, immunomodulation, regulation of Müller cell proliferation, upregulation of intermediate filaments, glial scar formation, and the generation of neural progenitor/stem cells. A proper understanding of the signaling mechanisms implicated in gliotic alterations of Müller cells is essential for the development of efficient therapeutic strategies that increase the supportive/protective and decrease the destructive roles of gliosis.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Liebigstrasse 10-14, D-04103 Leipzig, Germany.
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Role of retinal glial cells in neurotransmitter uptake and metabolism. Neurochem Int 2009; 54:143-60. [DOI: 10.1016/j.neuint.2008.10.014] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 10/15/2008] [Accepted: 10/20/2008] [Indexed: 11/30/2022]
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Olsen ML, Sontheimer H. Functional implications for Kir4.1 channels in glial biology: from K+ buffering to cell differentiation. J Neurochem 2008; 107:589-601. [PMID: 18691387 PMCID: PMC2581639 DOI: 10.1111/j.1471-4159.2008.05615.x] [Citation(s) in RCA: 229] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Astrocytes and oligodendrocytes are characterized by a very negative resting potential and a high resting permeability for K(+) ions. Early pharmacological and biophysical studies suggested that the resting potential is established by the activity of inwardly rectifying, Ba(2+) sensitive, weakly rectifying Kir channels. Molecular cloning has identified 16 Kir channels genes of which several mRNA transcripts and protein products have been identified in glial cells. However, genetic deletion and siRNA knock-down studies suggest that the resting conductance of astrocytes and oligodendrocytes is largely due to Kir4.1. Loss of Kir4.1 causes membrane depolarization, and a break-down of K(+) and glutamate homeostasis which results in seizures and wide-spread white matter pathology. Kir channels have also been shown to act as critical regulators of cell division whereby Kir function is correlated with an exit from the cell cycle. Conversely, loss of functional Kir channels is associated with re-entry of cells into the cell cycle and gliosis. A loss of functional Kir channels has been shown in a number of neurological diseases including temporal lobe epilepsy, amyotrophic lateral sclerosis, retinal degeneration and malignant gliomas. In the latter, expression of Kir4.1 is sufficient to arrest the aberrant growth of these glial derived tumor cells. Kir4.1 therefore represents a potential therapeutic target in a wide variety of neurological conditions.
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Affiliation(s)
- Michelle L Olsen
- Department of Neurobiology & Center for Glial Biology in Medicine, The University of Alabama Birmingham, Birmingham, Alabama 35294-0021, USA
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Müller cell gliosis in retinal organ culture mimics gliotic alterations after ischemia
in vivo. Int J Dev Neurosci 2008; 26:745-51. [DOI: 10.1016/j.ijdevneu.2008.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 07/02/2008] [Accepted: 07/03/2008] [Indexed: 11/18/2022] Open
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K+ currents fail to change in reactive retinal glial cells in a mouse model of glaucoma. Graefes Arch Clin Exp Ophthalmol 2008; 246:1249-54. [DOI: 10.1007/s00417-008-0872-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 03/26/2008] [Accepted: 05/11/2008] [Indexed: 10/22/2022] Open
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KUCHERYAVYKH YURIYV, SHUBA YAROSLAVM, ANTONOV SERGEIM, INYUSHIN MIKHAILY, CUBANO LUIS, PEARSON WADEL, KURATA HARLEY, REICHENBACH ANDREAS, VEH RÜDIGERW, NICHOLS COLING, EATON MISTYJ, SKATCHKOV SERGUEIN. Complex rectification of Müller cell Kir currents. Glia 2008; 56:775-90. [PMID: 18293411 PMCID: PMC9930535 DOI: 10.1002/glia.20652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although Kir4.1 channels are the major inwardly rectifying channels in glial cells and are widely accepted to support K+- and glutamate-uptake in the nervous system, the properties of Kir4.1 channels during vital changes of K+ and polyamines remain poorly understood. Therefore, the present study examined the voltage-dependence of K+ conductance with varying physiological and pathophysiological external [K+] and intrapipette spermine ([SP]) concentrations in Müller glial cells and in tsA201 cells expressing recombinant Kir4.1 channels. Two different types of [SP] block were characterized: "fast" and "slow." Fast block was steeply voltage-dependent, with only a low sensitivity to spermine and strong dependence on extracellular potassium concentration, [K+]o. Slow block had a strong voltage sensitivity that begins closer to resting membrane potential and was essentially [K+]o-independent, but with a higher spermine- and [K+]i-sensitivity. Using a modified Woodhull model and fitting i/V curves from whole cell recordings, we have calculated free [SP](in) in Müller glial cells as 0.81 +/- 0.24 mM. This is much higher than has been estimated previously in neurons. Biphasic block properties underlie a significantly varying extent of rectification with [K+] and [SP]. While confirming similar properties of glial Kir and recombinant Kir4.1, the results also suggest mechanisms underlying K+ buffering in glial cells: When [K+]o is rapidly increased, as would occur during neuronal excitation, "fast block" would be relieved, promoting potassium influx to glial cells. Increase in [K+]in would then lead to relief of "slow block," further promoting K+-influx.
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Affiliation(s)
- YURIY V. KUCHERYAVYKH
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - YAROSLAV M. SHUBA
- International Center of Molecular Physiology, National Academy of Sciences of Ukraine, Kiev, 01024 Ukraine
| | - SERGEI M. ANTONOV
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, 194223 Russia
| | - MIKHAIL Y. INYUSHIN
- Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - LUIS CUBANO
- Department of Anatomy and Cell Biology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - WADE L. PEARSON
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - HARLEY KURATA
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - ANDREAS REICHENBACH
- Paul Flechsig Institute of Brain Research, Leipzig University, D-04109 Leipzig, Germany
| | - RÜDIGER W. VEH
- Institute of Integrative Neuroanatomy, Charité, Philipstrasse 12, Berlin, Germany
| | - COLIN G. NICHOLS
- Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO
| | - MISTY J. EATON
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - SERGUEI N. SKATCHKOV
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR,Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR,Correspondence to: S. N. Skatchkov, Departments of Biochemistry and Physiology, School of Medicine, Universidad Central del Caribe, Box 60-327, Bayamón, Puerto Rico, USA 00960-6032.
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Localization of glial aquaporin-4 and Kir4.1 in the light-injured murine retina. Neurosci Lett 2008; 434:317-21. [DOI: 10.1016/j.neulet.2008.02.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 01/30/2008] [Accepted: 02/01/2008] [Indexed: 11/22/2022]
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Giaume C, Kirchhoff F, Matute C, Reichenbach A, Verkhratsky A. Glia: the fulcrum of brain diseases. Cell Death Differ 2007; 14:1324-35. [PMID: 17431421 DOI: 10.1038/sj.cdd.4402144] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neuroglia represented by astrocytes, oligodendrocytes and microglial cells provide for numerous vital functions. Glial cells shape the micro-architecture of the brain matter; they are involved in information transfer by virtue of numerous plasmalemmal receptors and channels; they receive synaptic inputs; they are able to release 'glio'transmitters and produce long-range information exchange; finally they act as pluripotent neural precursors and some of them can even act as stem cells, which provide for adult neurogenesis. Recent advances in gliology emphasised the role of glia in the progression and handling of the insults to the nervous system. The brain pathology, is, to a very great extent, a pathology of glia, which, when falling to function properly, determines the degree of neuronal death, the outcome and the scale of neurological deficit. Glial cells are central in providing for brain homeostasis. As a result glia appears as a brain warden, and as such it is intrinsically endowed with two opposite features: it protects the nervous tissue as long as it can, but it also can rapidly assume the guise of a natural killer, trying to eliminate and seal the damaged area, to save the whole at the expense of the part.
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Affiliation(s)
- C Giaume
- INSERM, U840 and Collège de France, Paris, France
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41
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Reichenbach A, Wurm A, Pannicke T, Iandiev I, Wiedemann P, Bringmann A. Müller cells as players in retinal degeneration and edema. Graefes Arch Clin Exp Ophthalmol 2007; 245:627-36. [PMID: 17219109 DOI: 10.1007/s00417-006-0516-y] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 12/02/2006] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Under normal conditions, Müller cells support neuronal activity and the integrity of the blood-retinal barrier, whereas gliotic alterations of Müller cells under pathological conditions may contribute to retinal degeneration and edema formation. A major function of Müller cells is the fluid absorption from the retinal tissue, which is mediated by transcellular water transport coupled to currents through potassium channels. METHODS Alterations of retinal Müller cells under pathological conditions were investigated by immunohistochemistry and recording their behavior under osmotic stress. RESULTS In animal models of various retinopathies, e.g., retinal ischemia, ocular inflammation, retinal detachment, and diabetes, it was found that Müller cells decrease the expression of their major potassium channel (Kir4.1). This alteration is associated with an impairment of the rapid water transport across Müller cell membranes, as recognizable in the induction of cellular swelling under hypoosmolar conditions. Osmotic swelling of Müller cells is also induced by oxidative stress and by inflammatory mediators such as arachidonic acid and prostaglandins. CONCLUSIONS The data suggest that a disturbed fluid transport through Müller cells is (in addition to vascular leakage) a pathogenic factor contributing to the development of retinal edema. Pharmacological re-activation of the retinal water clearance by Müller cells may represent an approach to the development of new edema-resolving drugs. Triamcinolone acetonide, which is clinically used to resolve edema, prevents osmotic swelling of Müller cells as it induces the release of endogenous adenosine and subsequent A1 receptor activation which results in the opening of ion channels. Apparently, triamcinolone resolves edema by both inhibition of vascular leakage and stimulation of retinal fluid clearance by Müller cells.
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Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Faculty of Medicine, University of Leipzig, Jahnallee 59, 04109, Leipzig, Germany
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Uckermann O, Wolf A, Kutzera F, Kalisch F, Beck-Sickinger AG, Wiedemann P, Reichenbach A, Bringmann A. Glutamate release by neurons evokes a purinergic inhibitory mechanism of osmotic glial cell swelling in the rat retina: activation by neuropeptide Y. J Neurosci Res 2006; 83:538-50. [PMID: 16435394 DOI: 10.1002/jnr.20760] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glial cell swelling is a central cause of ischemic edema in the brain and retina; however, the regulation of glial cell volume by endogenous factors in situ is largely unknown. In slices of the postischemic retina of the rat, the somata of glial (Müller) cells swell upon hypotonic stress that is not observed in slices of control retinas. We describe an endogenous signaling pathway that leads to inhibition of the osmotic glial cell swelling, and that is evoked by the release of glutamate from retinal neurons upon application of neuropeptide Y. Glutamate activates metabotropic glutamate receptors on swollen glial cells, which evokes a Ca2+ -independent purinergic signaling cascade that involves release of ATP, P2Y1 receptor activation, and transporter-mediated release of adenosine. Activation of A1 receptors causes the inhibition of osmotic glial cell swelling, by a protein kinase A-dependent activation of K+ and Cl- channels. It is proposed that the glutamate-evoked purinergic receptor signaling of glial cells is crucially involved in the cell volume homeostasis of the retina, and that this mechanism may contribute to the protective effect of adenosine in the ischemic tissue.
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Affiliation(s)
- Ortrud Uckermann
- Paul Flechsig Institute of Brain Research, Medical Faculty of the University of Leipzig, Leipzig, Germany
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Pannicke T, Iandiev I, Wurm A, Uckermann O, vom Hagen F, Reichenbach A, Wiedemann P, Hammes HP, Bringmann A. Diabetes alters osmotic swelling characteristics and membrane conductance of glial cells in rat retina. Diabetes 2006; 55:633-9. [PMID: 16505225 DOI: 10.2337/diabetes.55.03.06.db05-1349] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The development of edema in the diabetic retina may be caused by vascular leakage and glial cell swelling. To determine whether diabetic retinopathy alters the swelling characteristics of retinal glial cells and changes the properties of the glial membrane K+ conductance, isolated retinas and glial cells of rats were investigated at 4 and 6 months of chemical diabetes. After 6 months of hyperglycemia, application of a hypotonic solution to retinal slices induced swelling of glial cell bodies, a response not observed in control retinas. The osmotic glial cell swelling was blocked by inhibitors of phospholipase A2 or cyclooxygenase and by a thiol-reducing agent. Glial cells from diabetic retinas displayed a decrease of K+ currents that was associated with an altered subcellular distribution of the K+ conductance and a loss of perivascular Kir4.1 protein. The observation that swelling of cells in control retinas was inducible with K+ channel-blocking Ba2+ ions suggests a relationship between decreased K+ inward currents and osmotic cell swelling in diabetic retinas. The data show that glial cells in diabetic retinas are more sensitive to osmotic stress, which is associated with a decrease of K+ currents, than cells in control retinas. It is suggested that these alterations may be implicated in the development of diabetic retinal edema.
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Affiliation(s)
- Thomas Pannicke
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
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Iandiev I, Biedermann B, Bringmann A, Reichel MB, Reichenbach A, Pannicke T. Atypical gliosis in Müller cells of the slowly degenerating rds mutant mouse retina. Exp Eye Res 2006; 82:449-57. [PMID: 16154566 DOI: 10.1016/j.exer.2005.07.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Revised: 04/26/2005] [Accepted: 07/31/2005] [Indexed: 10/25/2022]
Abstract
Retinal Müller glial cells are known to undergo reactive changes (gliosis) in various retinal diseases. In virtually all cases studied, an upregulation of glial fibrillary acidic protein (GFAP) and a hypertrophy can be observed. Physiological alterations, such as a strong downregulation of inwardly rectifying K+ (Kir) currents, were found after retinal detachment (man, rabbit) and after ischemia/reperfusion (rat) but not in more slowly progressing retinal degenerations (Borna Disease Virus-infected rats, RCS rats). This led us to hypothesize that Müller cells respond with 'typical' reactive gliosis only to rapid but not to slow retinal degeneration. To test this hypothesis, we studied Müller cells from rds mutant mice (PrphRd2), which show a retinal degeneration of early onset and slow progression, resulting in a complete loss of photoreceptors after 9-12 months. In Müller cells of rds mice, we found immunoreactivity for GFAP, a marker of gliosis in Müller cells, from postnatal day 21 on, accompanied by a moderately increased membrane capacitance (taken as an indicator of hypertrophy), whereas no change in the expression of the Kir4.1 protein occurred in adult rds mice. We failed to observe significant changes in the membrane resistance and the membrane potential of cells from rds mice from first week after birth until 1 year of age. Current densities were decreased in cells from 3- and 5-week old rds mice. Furthermore, as in control cells from wildtype animals, these cells displayed dominant Kir currents, voltage-dependent Na+ currents, and glutamate uptake currents. These data support the idea that in mice as well as previously shown in rats, slow retinal degeneration induces an atypical gliosis of Müller cells.
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Affiliation(s)
- Ianors Iandiev
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Jahnallee 59, D-04109 Leipzig, Germany.
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Wurm A, Pannicke T, Iandiev I, Wiedemann P, Reichenbach A, Bringmann A. The developmental expression of K+ channels in retinal glial cells is associated with a decrease of osmotic cell swelling. Glia 2006; 54:411-23. [PMID: 16886204 DOI: 10.1002/glia.20391] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A major function of glial cells is the control of osmotic and ionic homeostasis, mediated by K+ and water movements predominantly through inwardly rectifying K+ (Kir) and aquaporin water channels. It has been suggested that K+ currents through Kir channels are implicated in the regulation of glial cell volume. Here, we investigated whether the developmental increase in Kir channel expression in Müller glial cells of the rat retina is associated with an alteration of cell volume regulation under anisoosmotic conditions. Around the time of eye opening at postnatal day (P) 15, developing retinal glial cells fully alter the profile of their membrane conductances, from a current pattern with prominent fast transient K+ and Na+ currents to a pattern of noninactivating currents through Kir and delayed rectifier K+ channels. Concomitantly, aquaporins-1 and -4 are expressed in the developing retina. This is accompanied by a conspicuous alteration of the swelling characteristics of cells; somata of immature glial cells in early postnatal retinas (P5-P15) swell under hypotonic stress but no swelling is inducible in mature cells at P18 and thereafter. However, glial cells at all developmental stages swell when their Kir channels are blocked by Ba2+. The postnatal maturation of Kir channel currents and volume regulation in retinal glial cells is delayed by visual deprivation. The data suggest that Kir channels are crucially involved in osmotic volume homeostasis of mature glial cells, and that the absence of Kir channels in immature cells is a major cause of their insufficient volume regulation.
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Affiliation(s)
- Antje Wurm
- Paul Flechsig Institute of Brain Research, University of Leipzig Medical Faculty, Leipzig, Germany
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Zhou M, Schools GP, Kimelberg HK. Development of GLAST(+) astrocytes and NG2(+) glia in rat hippocampus CA1: mature astrocytes are electrophysiologically passive. J Neurophysiol 2005; 95:134-43. [PMID: 16093329 DOI: 10.1152/jn.00570.2005] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glia show marked heterogeneity in terms of electrophysiology in the developing brain, and two major types can be identified based on GFAP or NG2 expression. However, it remains to be determined if such an electrophysiological diversity holds for the adult brain and how GFAP and NG2 lineage glia are associated with different electrophysiological phenotypes during the course of development. To address these fundamental questions, we performed in situ whole cell recording from morphologically identified glia from the rat hippocampal CA1 region from postnatal (P) days 1-106 and double-stained postrecorded cells with GLAST and NG2 antibodies. We found glia express mostly voltage-gated outward K(+) currents and also have inward Na(+) currents in the newborn (P1-P3), but these are no longer present after P22. They consist equally of GLAST(+) and NG2(+) cells in the newborn, but are mainly NG2(+) in juvenile animals (P4-P21). Glia showing voltage-gated outward and inward K(+) currents are also present at P1, peak at P5 and decline to a stationary level of approximately 10% in the adult. They are GLAST(+) astrocytes from newborn to juvenile but NG2(+) glia in the adult. Electrophysiologically passive glia first appear at P4 and increase to 91% in adults, of which 85% are GLAST(+). These results indicate that glial electrophysiological diversity occurs predominantly in the developing brain. While most glia in the NG2 lineage preserve a certain amount of voltage-gated ion conductances, mature GLAST(+) astrocytes are electrophysiologically passive.
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Affiliation(s)
- Min Zhou
- Neural and Vascular Biology, Ordway Research Inst., 150 New Scotland Ave., Albany, NY 12208, USA.
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Pannicke T, Uckermann O, Iandiev I, Wiedemann P, Reichenbach A, Bringmann A. Ocular inflammation alters swelling and membrane characteristics of rat Müller glial cells. J Neuroimmunol 2005; 161:145-54. [PMID: 15748953 DOI: 10.1016/j.jneuroim.2005.01.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 12/29/2004] [Accepted: 01/03/2005] [Indexed: 11/21/2022]
Abstract
Ocular inflammation is a common cause of retinal edema that may involve swelling of Müller glial cells. In order to investigate whether endotoxin-induced ocular inflammation in rats alters the swelling and membrane characteristics of Müller cells, lipopolysaccharide (LPS; 0.5%) was intravitreally injected. At 3 and 7 days after treatment, hypotonic challenge induced swelling of Müller cell somata that was not observed in non-treated control eyes. Müller cells of LPS-treated eyes displayed a downregulation of inward K(+) currents and upregulation of A-type K(+) currents that was associated with a decreased expression of Kir4.1 protein in retinal slices. The data suggest that ocular inflammation induces alterations of both the swelling characteristics and the K(+) channel expression of Müller cells.
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Affiliation(s)
- Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig Medical Faculty, D-04109 Leipzig, Germany
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Skatchkov SN, Eaton MJ, Shuba YM, Kucheryavykh YV, Derst C, Veh RW, Wurm A, Iandiev I, Pannicke T, Bringmann A, Reichenbach A. Tandem-pore domain potassium channels are functionally expressed in retinal (Müller) glial cells. Glia 2005; 53:266-76. [PMID: 16265669 DOI: 10.1002/glia.20280] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Tandem-pore domain (2P-domain) K+-channels regulate neuronal excitability, but their function in glia, particularly, in retinal glial cells, is unclear. We have previously demonstrated the immunocytochemical localization of the 2P-domain K+ channels TASK-1 and TASK-2 in retinal Müller glial cells of amphibians. The purpose of the present study was to determine whether these channels were functional, by employing whole-cell recording from frog and mammalian (guinea pig, rat and mouse) Müller cells and confocal microscopy to monitor swelling in rat Müller cells. TASK-like immunolabel was localized in these cells. The currents mediated by 2P-domain channels were studied in isolation after blocking Kir, K(A), K(D), and BK channels. The remaining cell conductance was mostly outward and was depressed by acid pH, bupivacaine, methanandamide, quinine, and clofilium, and activated by alkaline pH in a manner consistent with that described for TASK channels. Arachidonic acid (an activator of TREK channels) had no effect on this conductance. Blockade of the conductance with bupivacaine depolarized the Müller cell membrane potential by about 50%. In slices of the rat retina, adenosine inhibited osmotic glial cell swelling via activation of A1 receptors and subsequent opening of 2P-domain K+ channels. The swelling was strongly increased by clofilium and quinine (inhibitors of 2P-domain K+ channels). These data suggest that 2P-domain K+ channels are involved in homeostasis of glial cell volume, in activity-dependent spatial K+ buffering and may play a role in maintenance of a hyperpolarized membrane potential especially in conditions where Kir channels are blocked or downregulated.
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Affiliation(s)
- S N Skatchkov
- CMBN, Department of Biochemistry, School of Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico 00960-6032.
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