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Updated: Jul 30, 2026
10:11
Cut-loading: A Useful Tool for Examining the Extent of Gap Junction Tracer Coupling Between Retinal Neurons
Published on: January 12, 2012
Different functional types of bipolar cells use different gap-junctional proteins
Bin Lin1, Tatjana C Jakobs, Richard H Masland
1Howard Hughes Medical Institute, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. blin@helix.mgh.harvard.edu
Summary
This study reveals that type 357 ON cone bipolar cells express connexin36 (Cx36) at their gap junctions with AII amacrine cells, clarifying connexin expression in retinal signal transmission.
Area of Science:
- Neuroscience
- Retinal Physiology
- Cell Biology
Background:
- Rod signals are relayed to ON retinal ganglion cells via gap junctions between AII amacrine cells and ON bipolar cells.
- AII amacrine cells are known to express connexin36 (Cx36), but its presence in ON cone bipolar cells remains unclear.
Purpose of the Study:
- To investigate the expression of connexins, specifically Cx36, in ON cone bipolar cells.
- To determine which connexin types are involved in the gap junctions between AII amacrine cells and different types of ON cone bipolar cells.
Main Methods:
- Utilized a transgenic mouse line with green fluorescent protein (GFP) labeling specific ON cone bipolar cells (type 357).
- Performed immunostaining for Cx36 and Cx45 on retinal sections and whole mounts.
- Conducted single-cell reverse transcription-PCR (RT-PCR) to confirm connexin gene expression in identified bipolar cells.
Main Results:
- Strong Cx36 immunostaining was observed in the axon terminals of GFP-labeled type 357 ON cone bipolar cells.
- RT-PCR confirmed Cx36 expression in type 357 bipolar cells, while Cx45 was found in other, GFP-negative ON bipolar cell types.
- Different ON cone bipolar cell types express distinct connexins (Cx36 or Cx45) at their gap junctions with AII amacrine cells.
Conclusions:
- Type 357 ON cone bipolar cells utilize Cx36 for their gap junctions with AII amacrine cells.
- The findings indicate a differential expression of connexins among ON cone bipolar cell types, influencing retinal circuitry.
- This clarifies the molecular basis of rod signal transmission to ON retinal ganglion cells.
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