Abstract
Purpose :
Previously we identified POU6F2 as a genetic link between central corneal thickness (CCT) and risk of open-angle glaucoma. The present study is designed to characterize the POU6F2-positive retinal ganglion cells (RGCs).
Methods :
The Thy1-YFP-H mouse was used to identify the structure of POU6F2-positive RGCs in the retina. In the retina of the Thy1-YFP-H mouse approximately 3% of the RGCs are labeled with yellow fluorescent protein. These retinas were stained for POU6F2 to identify the morphology of the POU6F2 subtypes in 3D reconstructions of the labeled RGCs. We also examined the Pou6f2 null mouse to determine the effects of knocking out this gene. The number of RPBMS RGCs were counted and visual function was tested with electroretinogram (ERG) and optomotor response (OMR) comparing Pou6f2 knockout mice to their Pou6f2 wildtype littermates. DBA/2J glaucoma models were used to test the role of POU6F2 in injury.
Results :
In the retina POU6F2 labels 32.9% of the RGCs (16.1% heavily and 16.8% lightly labeled). In 3D constructions of Thy1-YFP-H positive RGCs, the heavily labeled POU6F2+ cells had dendrites in the inner plexiform layer that were bistratified and appeared to be on-off directionally selective cells. The lightly labeled POU6F2 RGCs displayed 3 different dendritic distributions, with dendrites in the ON sub-laminae only, OFF sub-laminae only, or bistratified. Interestingly, the POU6F2+ cells do not co-stain with CARTPT, a known ON-OFF direction selective RGC marker. When we examined the retinal anatomy of the Pou6f2 KO mice there was a loss of 16% of the cells relative to the wild-type littermates. To determine if the loss of these cells could affect visual function, we examined the performance of the mice using both ERG and OMR. We found no differences in the ERGs between the Pou6f2-null mice and the wild-type mice. There was a significant depression (p < 0.05) in both the contrast sensitivity and the visual acuity in Pou6f2 null mice as compared to the wild type littermates. In DBA/2J glaucoma model, at 8 months of age there was a 22% loss of RGCs (labeled with RBPMS) while there was 73% loss of the heavily labeled POU6F2 RGCs (p < 0.01), suggesting that the POU6F2 cells are the first to die during glaucomatous damage.
Conclusions :
Pou6f2 is a marker for a group of previously unidentified RGCs that are sensitive to injury. Pou6f2 plays a critical role in retinal development and normal visual function.
This is a 2020 ARVO Annual Meeting abstract.