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Aqp4 kir4.1 retina

Sandrine Joly, Dana A Dodd, Benjamin F Grewe, Vincent Pernet
In the adult retina, we have previously shown that Nogo-A was highly expressed in Müller glia. However, the role of Nogo-A in the glial cell physiology is not clear. In this study, we investigated the possible influence that Nogo-A may exert on other polarized molecules in Müller cells, in particular inwardly rectifying potassium channel 4.1 (Kir4.1) and aquaporin 4 (AQP4) that respectively control potassium and water exchange in glial cells. Our results showed that adenovirus-mediated Nogo-A overexpression with AdNogo-A increased the immunofluorescent signal of Kir4...
August 3, 2016: Neuroscience Letters
S Lassiale, F Valamanesh, C Klein, D Hicks, M Abitbol, C Versaux-Botteri
Muller glial cells (MGC) are essential for normal functioning of retina. They are especially involved in potassium (K+) and water homeostasis, via inwardly rectifying K+ (Kir 4.1) and aquaporin-4 (AQP4) channels respectively. Because MGC appear morphologically and functionally altered in most retinal pathologies, we studied the expression of AQP 4 and Kir 4.1 during the time course of progressive retinal degeneration in Royal College of Surgeons (RCS) rats, an animal model for the hereditary human retinal degenerative disease Retinitis pigmentosa...
July 2016: Experimental Eye Research
Lucia Gaddini, Monica Varano, Andrea Matteucci, Cinzia Mallozzi, Marika Villa, Flavia Pricci, Fiorella Malchiodi-Albedi
The effects of the anti-Vascular Endothelial Growth Factor (VEGF) drugs ranibizumab and aflibercept were studied in Müller glia in primary mixed cultures from rat neonatal retina. Treatment with both agents induced activation of Müller glia, demonstrated by increased levels of Glial Fibrillary Acidic Protein. In addition, phosphorylated Extracellular-Regulated Kinase 1/2 (ERK 1/2) showed enhanced immunoreactivity in activated Müller glia. Treatment with aflibercept induced an increase in K(+) channel (Kir) 4...
April 2016: Experimental Eye Research
Andrew O Jo, Daniel A Ryskamp, Tam T T Phuong, Alan S Verkman, Oleg Yarishkin, Nanna MacAulay, David Križaj
Brain edema formation occurs after dysfunctional control of extracellular volume partly through impaired astrocytic ion and water transport. Here, we show that such processes might involve synergistic cooperation between the glial water channel aquaporin 4 (AQP4) and the transient receptor potential isoform 4 (TRPV4), a polymodal swelling-sensitive cation channel. In mouse retinas, TRPV4 colocalized with AQP4 in the end feet and radial processes of Müller astroglia. Genetic ablation of TRPV4 did not affect the distribution of AQP4 and vice versa...
September 30, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Ophélie Vacca, Marie Darche, David V Schaffer, John G Flannery, José-Alain Sahel, Alvaro Rendon, Deniz Dalkara
Formation and maintenance of the blood-retinal barrier (BRB) is required for proper vision and breaching of this barrier contributes to the pathology in a wide variety of retinal conditions such as retinal detachment and diabetic retinopathy. Dystrophin Dp71 being a key membrane cytoskeletal protein, expressed mainly in Müller cells, its absence has been related to BRB permeability through delocalization and down-regulation of the AQP4 and Kir4.1 channels. Dp71-null mouse is thus an excellent model to approach the study of retinal pathologies showing blood-retinal barrier permeability...
March 2014: Glia
Patricia Köferl, Margrit Hollborn, Jiri Rehak, Ianors Iandiev, Sladjana Dukic-Stefanovic, Peter Wiedemann, Leon Kohen, Andreas Bringmann, Matus Rehak
BACKGROUND: To investigate the effect of induced arteriolar constriction (AC) on alterations in gene expression of factors implicated in the development of edema in branch retinal vein occlusion (BRVO). METHODS: In Brown-Norway rats, BRVO was induced by laser photocoagulation of the veins in one half of the retina. AC of the afferent arterioles was performed 30 min later. We then determined the expression of Vegfa, Vegfb, Pedf, Kir4.1, Aqp4, Aqp1, Il1ß, and Il6 with real-time polymerase chain reaction (RT-PCR) in the neuroretina and retinal pigment epithelium (RPE) after 1, 3, and 7 days...
February 2014: Graefe's Archive for Clinical and Experimental Ophthalmology
Franziska Drechsler, Patricia Köferl, Margrit Hollborn, Peter Wiedemann, Andreas Bringmann, Leon Kohen, Matus Rehak
PURPOSE: To determine the effect of intravitreal bevacizumab and anti-vascular endothelial growth factor (VEGF) antibodies on the gene expression in the neural retina in a rat model of central retinal vein occlusion (CRVO). METHODS: The CRVO was induced by laser photocoagulation of all retinal veins. The animals were divided into 3 groups (in each, n = 16): group CRVO only without any further treatment, group CRVO with bevacizumab, and group CRVO with anti-VEGF antibodies...
2012: Ophthalmic Research
Margrit Hollborn, Elke Ulbricht, Katja Rillich, Sladjana Dukic-Stefanovic, Antje Wurm, Lysann Wagner, Andreas Reichenbach, Peter Wiedemann, Gloria Astrid Limb, Andreas Bringmann, Leon Kohen
PURPOSE: To determine whether the human Müller cell line Moorfields/Institute of Ophthalmology-Müller 1 (MIO-M1) expresses opsins. METHODS: The gene expression of opsins was determined by reverse-transcription PCR (RT-PCR). The presence of opsin proteins was determined by western blotting and immunocytochemistry. The light sensitivity of the cells was examined with imaging experiments using the calcium-sensitive dye Fluo-4. RESULTS: MIO-M1 cells express glial (glutamine synthase [GLUL], vimentin [VIM], glial fibrillary acidic protein [GFAP], cellular retinaldehyde-binding protein [RLBP1], glial high-affinity glutamate transporter [SLCA1], aquaporin-4 [AQP4], inwardly rectifying potassium channel Kir4...
2011: Molecular Vision
Eric Wersinger, Agnès Bordais, Yannick Schwab, Abdoulaye Sene, Romain Bénard, Violaine Alunni, José-Alain Sahel, Alvaro Rendon, Michel J Roux
PURPOSE. The roles of dystrophins in retinal physiology remain elusive. The lack of proper clustering of the potassium channel Kir4.1 and of the aquaporin AQP4 was proposed to be the basis of the ERG abnormality observed in many Duchenne muscular dystrophy (DMD) patients. However, the electroretinogram of Dp71-null mice, in which this clustering is disrupted, shows only a moderate reduction of the b-wave with no change in the implicit times. Additionally, the deficit in color discrimination found in DMD patients is hard to explain through the known expression of DMD gene products...
2011: Investigative Ophthalmology & Visual Science
Min Zhao, Elodie Bousquet, Fatemeh Valamanesh, Nicolette Farman, Jean-Claude Jeanny, Frederic Jaisser, Francine F Behar-Cohen
PURPOSE: Glucocorticoids are used to treat macular edema, although the mechanisms underlying this effect remain largely unknown. The authors have evaluated in the normal and endotoxin-induced uveitis (EIU) rats, the effects of dexamethasone (dex) and triamcinolone acetonide (TA) on potassium channel Kir4.1 and aquaporin-4 (AQP4), the two main retinal Müller glial (RMG) channels controlling retinal fluid movement. METHODS: Clinical as well as relatively low doses of dex and TA were injected in the vitreous of normal rats to evaluate their influence on Kir4...
August 2011: Investigative Ophthalmology & Visual Science
Y Zhang, G Xu, Q Ling, C Da
This study examined aquaporin 4 (AQP4) and Kir4.1 (a potassium channel subunit) in normal and diabetic adult Sprague-Dawley rats, and determined the effect of minocycline treatment. Retinal expression of the AQP4 and Kir4.1 genes was examined using double immuno fluorescence, Western blot analysis, and real-time reverse transcription-polymerase chain reaction. Retinal levels of vascular endothelial growth factor (VEGF), ionized calcium-binding adaptor molecule (Iba)-1 and interleukin (IL)-1β were also ascertained...
2011: Journal of International Medical Research
Matus Rehak, Franziska Drechsler, Patricia Köferl, Margrit Hollborn, Peter Wiedemann, Andreas Bringmann, Leon Kohen
PURPOSE: The aim of this study was to investigate the effects of intravitreal triamcinolone acetonide on the alterations in retinal gene expression in a rat model of central retinal vein occlusion (CRVO). METHODS: In one eye of adult Brown Norway rats (n = 77) CRVO was induced with laser photocoagulation of all retinal veins near to the optic disk after intraperitoneal injection of 0.2 ml of 10% sodium fluorescein. The gene expression was investigated using RT-PCR separately in the neural retina and retinal pigment epithelium (RPE) 1, 3, 7, and 14 days after CRVO induction...
August 2011: Graefe's Archive for Clinical and Experimental Ophthalmology
Christina Eberhardt, Barbara Amann, Annette Feuchtinger, Stefanie M Hauck, Cornelia A Deeg
Reactive gliosis is a well-established response to virtually every retinal disease. Autoimmune uveitis, a sight threatening disease, is characterized by recurrent relapses through autoaggressive T-cells. The purpose of this study was to assess retinal Müller glial cell function in equine recurrent uveitis (ERU), a spontaneous disease model resembling the human disease, by investigating membrane proteins implicated in ion and water homeostasis. We found that Kir2.1 was highly expressed in diseased retinas, whereas Kir4...
May 2011: Glia
Melinda J Goodyear, Sheila G Crewther, Melanie J Murphy, Loretta Giummarra, Agnes Hazi, Barbara M Junghans, David P Crewther
PURPOSE: Spatial co-localization of aquaporin water channels (AQP4) and inwardly rectifying potassium ion channels (Kir4.1) on the endfeet regions of glial cells has been suggested as the basis of functionally interrelated mechanisms of osmoregulation in brain edema. The aim of this study was to investigate the spatial and temporal changes in the expression of AQP4 and Kir4.1 channels in an avascular retina during the first week of the optical induction of refractive errors. METHODS: Three-day-old hatchling chicks were randomly assigned to three groups and either did not wear lenses or were monocularly goggled with +/-10D lenses for varying times up to 7 days before biometric assessment...
2010: Molecular Vision
Hui Ren, Gezhi Xu, Jiang Qian, Min Zhou, John Gonzales, Yingqin Ni
SAP97 is thought to play key roles in synapse assembly and synaptic plasticity. This study was carried out to determine whether it is involved in the Müller cell response to blue light injury. In light-injured rats, obvious intracellular edema in the outer retina was observed by transmission electron microscopy. The immunostaining of SAP97 was upregulated and concentrated in the Müller cell processes after photic injury, which was similar to the changes of AQP4 and the inwardly rectifying potassium channel, Kir4...
August 23, 2010: Neuroreport
Min Zhao, Fatemeh Valamanesh, Isabelle Celerier, Michèle Savoldelli, Laurent Jonet, Jean-Claude Jeanny, Frederic Jaisser, Nicolette Farman, Francine Behar-Cohen
Glucocorticoids reduce diabetic macular edema, but the mechanisms underlying glucocorticoid effects are imperfectly elucidated. Glucocorticoids may bind to glucocorticoid (GR) and mineralocorticoid (MR) receptors. We hypothesize that MR activation may influence retinal hydration. The effect of the MR agonist aldosterone (24 h) on ion/water channel expression (real-time PCR, Western blot, immunofluorescence) was investigated on cultured retinal Müller glial cells (RMGs, which contribute to fluid homeostasis in the retina), in Lewis rat retinal explants, and in retinas from aldosterone-injected eyes...
September 2010: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Adnan Dibas, Hidehiro Oku, Masayuki Fukuhara, Takuji Kurimoto, Tsunehiko Ikeda, Rajkumar V Patil, Najam A Sharif, Thomas Yorio
PURPOSE: Changes in the expression of water channels (aquaporins; AQP) have been reported in several diseases. However, such changes and mechanisms remain to be evaluated for retinal injury after optic nerve crush (ONC). This study was designed to analyze changes in the expression of AQP4 (water selective channel) and AQP9 (water and lactate channel) following ONC in the rat. METHODS: Rat retinal ganglion cells (RGCs) were retrogradely labeled by applying FluoroGold onto the left superior colliculus 1 week before ONC...
2010: Molecular Vision
Abdoulaye Sene, Ramin Tadayoni, Thomas Pannicke, Antje Wurm, Brahim El Mathari, Romain Benard, Michel Joseph Roux, David Yaffe, Dominique Mornet, Andreas Reichenbach, Jose-Alain Sahel, Alvaro Rendon
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...
2009: PloS One
Patrice E Fort, Abdoulaye Sene, Thomas Pannicke, Michel J Roux, Valerie Forster, Dominique Mornet, Uri Nudel, David Yaffe, Andreas Reichenbach, Jose A Sahel, Alvaro Rendon
The dystrophin-associated proteins (DAPs) complex consisting of dystroglycan, syntrophin, dystrobrevin, and sarcoglycans in muscle cells is associated either with dystrophin or its homolog utrophin. In rat retina, a similar complex was found associated with dystrophin-Dp71 that serves as an anchor for the inwardly rectifying potassium channel Kir4.1 and the aqueous pore, aquaporin-4 (AQP4). Here, using immunofluorescence imaging of isolated retinal Müller glial cells and co-immunoprecipitation experiments performed on an enriched Müller glial cells end-feet fraction, we investigated the effect of Dp71 deletion on the composition, anchoring, and membrane localization of the DAPs-Kir4...
April 15, 2008: Glia
Jennifer Rurak, Geoffroy Noel, Leona Lui, Bharat Joshi, Hakima Moukhles
The dystroglycan protein complex provides a link between the cytoskeleton and the extracellular matrix (ECM). Defective O-glycosylation of alpha-dystroglycan (alpha-DG) severs this link leading to muscular dystrophies named dystroglycanopathies. These are characterized not only by muscle degeneration, but also by brain and ocular defects. In brain and retina, alpha-DG and ECM molecules are enriched around blood vessels where they may be involved in localizing the inwardly rectifying potassium channel, Kir4...
December 2007: Journal of Neurochemistry
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