Different functional types of bipolar cells use different gap-junctional proteins.
Rod signals are transmitted to ON retinal ganglion cells by means of gap junctions between AII amacrine cells and ON bipolars. The AII amacrine cells are known to express connexin36 (Cx36), but previous studies of Cx36 in ON cone bipolars have been ambiguous. Here, we studied bipolar cells in a transgenic mouse line that expresses high levels of green fluorescent protein (GFP) in one type of ON cone bipolar cell. We found strong Cx36 immunostaining in the axon terminals of the GFP-labeled type 357 bipolar cells in both vertical sections and whole mounts of the retina. This finding was confirmed by single-cell immunostaining and single-cell reverse transcription-PCR (RT-PCR). As reported previously (Maxeiner et al., 2005), Cx45 was found in some ON bipolar cells, but RT-PCR showed Cx36 and not Cx45 to be expressed by the type 357 bipolar cells. Some of the remaining GFP-negative bipolar cells expressed Cx45 but not Cx36. It appears that different types of ON cone bipolar cells express different connexins at their gap junctions with AII amacrine cells.
Lin
Bin
B
Howard Hughes Medical Institute, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. blin@helix.mgh.harvard.edu
Jakobs
Tatjana C
TC
Masland
Richard H
RH
D025042:Amacrine Cells / Q000502:physiology; D000818:Animals; D002450:Cell Communication; D017630:Connexins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D005456:Fluorescent Dyes / Q000032:analysis; D017629:Gap Junctions / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D008845:Microinjections; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051245:Retinal Bipolar Cells / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097004:Gap Junction delta-2 Protein
D017630:Connexins; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000097004:Gap Junction delta-2 Protein; C082920:connexin 45