The immunocytochemical localization of connexin 36 at rod and cone gap junctions in the guinea pig retina.
Connexin 36 (Cx36) is a channel-forming protein found in the membranes of apposed cells, forming the hexameric hemichannels of intercellular gap junction channels. It localizes to certain neurons in various regions of the brain including the retina. We characterized the expression pattern of neuronal Cx36 in the guinea pig retina by immunocytochemistry using specific antisera against Cx36 and green/red cone opsin or recoverin. Strong Cx36 immunoreactivity was visible in the ON sublamina of the inner plexiform layer and in the outer plexiform layer, as punctate labelling patterns. Double-labelling experiments with antibody directed against Cx36 and green/red cone opsin or recoverin showed that strong clustered Cx36 immunoreactivity localized to the axon terminals of cone or close to rod photoreceptors. By electron microscopy, Cx36 immunoreactivity was visible in the gap junctions as well as in the cytoplasmic matrices of both sides of cone photoreceptors. In the gap junctions between cone and rod photoreceptors, Cx36 immunoreactivity was only visible in the cytoplasmic matrices of cone photoreceptors. These results clearly indicate that Cx36 forms homologous gap junctions between neighbouring cone photoreceptors, and forms heterologous gap junctions between cone and rod photoreceptors in guinea pig retina. This focal location of Cx36 at the terminals of the photoreceptor suggests that rod photoreceptors can transmit rod signals to the pedicle of a neighbouring cone photoreceptor via Cx36, and that the cone in turn signals to corresponding ganglion cells via ON and OFF cone bipolar cells.
Lee
Eun-Jin
EJ
Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
Han
Jung-Won
JW
Kim
Hyun-Ju
HJ
Kim
In-Beom
IB
Lee
Mun-Yong
MY
Oh
Su-Ja
SJ
Chung
Jin-Woong
JW
Chun
Myung-Hoon
MH
D000818:Animals; D015153:Blotting, Western; D064026:Calbindins; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism*; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D006168:Guinea Pigs; D051597:Hippocalcin; D007150:Immunohistochemistry; D008074:Lipoproteins; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D016253:Microscopy, Immunoelectron / Q000379:methods; D009419:Nerve Tissue Proteins; D051603:Recoverin; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism* / Q000648:ultrastructure; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism* / Q000648:ultrastructure; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D000097004:Gap Junction delta-2 Protein
D064026:Calbindins; D002135:Calcium-Binding Proteins; D002232:Carbocyanines; D017630:Connexins; D005136:Eye Proteins; D051597:Hippocalcin; D008074:Lipoproteins; D009419:Nerve Tissue Proteins; D051603:Recoverin; D064030:S100 Calcium Binding Protein G; D000097004:Gap Junction delta-2 Protein; C100585:connexin 35 protein, vertebrate; C089187:cyanine dye 3