Subtypes of Retinal Müller Glial Cells as Adaptations to Specialized Vision
Final Report Abstract
Research on glial cells in the last decades revealed a lot of general functions of these cells. However, much less is known about functional specialization and adaptation of subtypes of glial cells to the specific area of the nervous system where they are located. Müller cells are the dominating glial cells of the vertebrate retina. They display a great morphological variability between different species. It has been found that Müller cells express a number of ion and water channels as well as transport proteins in their cell membrane. We demonstrate that Müller cells from almost all investigated species from all vertebrate classes (fishes, amphibians, reptiles, birds, mammals) are characterized by a dominant inwardly rectifying K+ conductance which can be largely blocked by Ba2+ ions. Moreover, a number of channels and receptors have been observed in Müller cells, some of them occur in a species-specific manner. In addition to membrane channels, Müller cells express metabotropic receptors. Activation of metabotropic nucleotide P2Y receptors evokes intracellular Ca2+ increases or even Ca2+ waves. Such signaling processes can be induced by mechanical stimulation. We have demonstrated that Ca2+ signaling after mechanical stimulation in the avascular guinea pig retina shows differences to similar processes in the vascularized rat retina, which might be caused by the lack of gap junction-coupled astrocytes in avascular retinae. We observed that in elephants, which are precocial animals, Müller cells are almost mature in many of their properties even at birth. Müller cells show similarities to radial glial cells which may represent an archetype of macroglial cells. Radial glial cells from vertebrates and echinoderms express SCO-spondin (SCO = subcommissural organ). This protein was detected immunohistochemically in the nervous system of hemichordates and protostomes from different taxa. These data suggest that radial glial cells are a characteristic phenomenon in the nervous system of all bilaterian animals.
Publications
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(2015) Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application. Exp Eye Res 139:37-47
Iseli HP, Körber N, Karl A, Koch C, Schuldt C, Penk A, Liu Q, Huster D, Käs J, Reichenbach A, Wiedemann P, Francke M
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(2015) Retinal functional alterations in mice lacking intermediate filament proteins GFAP and vimentin. FASEB J 29:4815-4828
Wunderlich KA, Tanimoto N, Grosche A, Zrenner E, Pekny M, Reichenbach A, Seeliger MW, Pannicke T, Perez MT
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(2016) Scleral cross-linking by riboflavin and blue light application in young rabbits: damage threshold and eye growth. Graefes Arch Clin Exp Ophthalmol 254:109-122
Iseli HP, Körber N, Koch C, Karl A, Penk A, Huster D, Reichenbach A, Wiedemann P, Francke M
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(2016) The ultrastructure of rabbit sclera after scleral crosslinking with riboflavin and blue light of different intensities. Graefes Arch Clin Exp Ophthalmol 254:1567-1577
Karl A, Makarov FN, Koch C, Körber N, Schuldt C, Krüger M, Reichenbach A, Wiedemann P, Bringmann A, Iseli HP, Francke M
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(2017) Comparative electrophysiology of retinal Müller glial cells – a survey on vertebrate species. Glia 65:533-568
Pannicke T, Chao TI, Reisenhofer M, Francke M, Reichenbach A
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(2017) Does the foveal shape influence the image formation in human eyes? Adv Opt Techn 6:403-410
Frey K, Zimmerling B, Scheibe P, Rauscher FG, Reichenbach A, Francke M, Brunner R
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(2017) Early evolution of radial glia cells in Bilateria. Proc R Soc B 284:20170743
Helm C, Karl A, Beckers P, Kaul-Strehlow S, Ulbricht E, Kourtesis I, Kuhrt H, Hausen H, Bartolomaeus T, Reichenbach A, Bleidorn C
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(2017) The retina of Asian and African elephants: comparison of newborn and adult. Brain Behav Evol 89:84-103
Kuhrt H, Bringmann A, Härtig W, Wibbelt G, Peichl L, Reichenbach A
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(2017) Two different mechanosensitive calcium responses in Müller glial cells of the guinea pig retina: differential dependence on purinergic receptor signaling. Glia 65:62-74
Agte S, Pannicke T, Ulbricht E, Reichenbach A, Bringmann A
