POU6F2 Positive Retinal Ganglion Cells a Novel Group of ON-OFF Directionally Selective Subtypes in the Mouse Retina

Abstract

PurposePreviously 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). MethodsThe 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 were 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.Multiple retinal cell markers were also co-stained with POU6F2 to characterize the molecular signature of the POU6F2-positive RGCs. DBA/2J glaucoma models were used to test the role of POU6F2 in injury. ResultsIn the retina POU6F2 labels 32.9% of the RGCs in the DBA/2J retina (16.1% heavily and 16.8% lightly labeled). In 3D constructions of Thy1-YFP-H positive RGCs, the heavily labeled POU6F2-positive 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 sublaminae only, OFF sublaminae only, or bistratified. The POU6F2-positive cells partially co-stained with Cdh6. The POU6F2-positive cells do not co-stain with CART and SATB2 (markers for ON-OFF directionally selective RGC), SMI32 (a marker for alpha RGCs), or ChAT and GAD67(markers for amacrine cells). The POU6F2-positive cells were sensitive to injury. 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. ConclusionsPOU6F2 is a marker for a novel group of RGC subtypes that are ON-OFF directionally selective RGCs that are sensitive to glaucomatous injury.

Sonic hedgehog-dependent recruitment of GABAergic interneurons into the developing visual thalamus

“…Clusters 16, 19, and 32 were notable for showing high SHH expression ( Figure 3C ). The transcription factor Pou6f2 reported to specify these RGC types ( Rheaume et al, 2018 ) is expressed in a novel class of On–Off direction selective RGCs (DSGCs) ( Li et al, 2020 ). Conversely, RGC clusters 30 and 40 that are defined by transcription factor Satb2 ( Rheaume et al, 2018 ) showed very low or no expression of SHH ( Figure 3C ).…”

Sonic hedgehog-dependent recruitment of GABAergic interneurons into the developing visual thalamus

“…Clusters 16, 19, and 32 were notable for showing high SHH expression (Figure 3c). The transcription factor Pou6f2 reported to specify these RGC types (Rheaume et al, 2018) is expressed in a novel class of On-OFF direction selective RGCs (DSGCs) (Li et al, 2020).…”

Commonalities of optic nerve injury and glaucoma-induced neurodegeneration: Insights from transcriptome-wide studies

“…This latter effect may even be further exaggerated by the differential susceptibility of RGC subtypes to insult. Some RGC types, like the heavily labeled POU6F2 RGCs ( Li et al, 2019 ) are very sensitive to glaucomatous injury ( King et al, 2018 ), while other subtypes, like the intrinsically photosensitive RGCs, are resistant to injury ( Cui et al, 2015 ; Perez de Sevilla Muller et al, 2014 ; Robinson and Madison, 2004 ). Thus, at any one time in a naturally occurring glaucoma model, a small number of RGCs are undergoing cell death and it is likely that the specific makeup of RGC subtypes differs over time.…”

“…Only a few CART positive cells remain in the mouse retina 14 days following crush. The most sensitive cells to injury appear to be RGCs heavily labeled with POU6F2 ( King et al, 2018 ; Li et al, 2019 ). In the DBA/2J mouse model of glaucoma, heavily-labeled POU6F2 RGC subtypes were selective lost early in glaucoma ( King et al, 2018 ; Li et al, 2019 ).…”

“…The most sensitive cells to injury appear to be RGCs heavily labeled with POU6F2 ( King et al, 2018 ; Li et al, 2019 ). In the DBA/2J mouse model of glaucoma, heavily-labeled POU6F2 RGC subtypes were selective lost early in glaucoma ( King et al, 2018 ; Li et al, 2019 ). We observed that 16% of the RGCs are POU6F2-positive but not in the CART positive RGCs, indicating that they are a novel ON-OFF directionally selective RGC subtype that is uniquely sensitive to glaucomatous injury ( Li et al, 2019 ).…”