title: Connexin57 is expressed in dendro-dendritic and axo-axonal gap junctions of mouse horizontal cells and its distribution is modulated by light.
abstract: Mouse horizontal cells are coupled by gap junctions composed of connexin57. These gap junctions are regulated by ambient light via multiple neuromodulators including dopamine. In order to analyze the distribution and structure of horizontal cell gap junctions in the mouse retina, and examine the effects of light adaptation on gap junction density, we developed antibodies that detect mouse retinal connexin57. Using immunohistochemistry in retinal slices, flat-mounted retinas, and dissociated retinal cells, we showed that connexin57 is expressed in the dendrites and axon terminal processes of mouse horizontal cells. No staining was found in retinas of connexin57-deficient mice. Significantly more connexin57-positive puncta were found in the distal than in the proximal outer plexiform layer, indicating a higher level of expression in axon terminal processes than in the dendrites. We also examined the gap junctions using immunoelectron microscopy and showed that connexin57 does not form hemichannels in the horizontal cell dendritic tips. Light adaptation resulted in a significant increase in the number of connexin57-immunoreactive plaques in the outer plexiform layer, consistent with previously reported effects of light adaptation on connexin57 expression in the mouse retina. This study shows for the first time the detailed location of connexin57 expression within mouse horizontal cells, and provides the first ultrastructural data on mouse horizontal cell gap junctions.
authors.affiliation: Department of Neurobiology, University of Oldenburg, D-26111 Oldenburg, Germany. ulrike.janssen.bienhold@uni-oldenburg.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Janssen-Bienhold
authors.forename: Jennifer
authors.initials: J
authors.lastname: Trümpler
authors.forename: Gerrit
authors.initials: G
authors.lastname: Hilgen
authors.forename: Konrad
authors.initials: K
authors.lastname: Schultz
authors.forename: Luis Pérez De Sevilla
authors.initials: LP
authors.lastname: Müller
authors.forename: Stephan
authors.initials: S
authors.lastname: Sonntag
authors.forename: Karin
authors.initials: K
authors.lastname: Dedek
authors.forename: Petra
authors.initials: P
authors.lastname: Dirks
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
authors.forename: Reto
authors.initials: R
authors.lastname: Weiler
mesh_terms: D000221:Adaptation, Ocular; D000818:Animals; D000906:Antibodies; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D015153:Blotting, Western; D017630:Connexins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism* / Q000648:ultrastructure; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016253:Microscopy, Immunoelectron; D010775:Photic Stimulation; D051248:Retinal Horizontal Cells / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D000906:Antibodies; D017630:Connexins; C119811:Gja10 protein, mouse