Effects of Glaucoma on Chrna6 Expression in the Retina

Abstract

Purpose: Recent advances in technology now provide tools capable of tracking genome-wide expression changes occurring in progressive pathological processes. The present experiments were carried out to determine if acetylcholine receptor α 6 subunit (Chrna6) is a reliable retinal ganglion cell (RGC) marker in adult mouse eyes and if Chrna6 expression can be used to track progressive loss of RGCs, such as is observed in the DBA/2J glaucoma model.

Methods: Data sets derived from the BXD strains were used to extract gene expression signatures for RGCs. Pooled retinas from DBA/2J or C57BL/6J cases at 1–3 months, 12 months, and 16–17 months were prepared for gene-array and RT-PCR analysis. Globes were fixed in paraformaldehyde and sectioned for immunofluorescence with antibodies against Chrna6.

Results: Chrna6 has a cellular expression signature for RGCs with high correlation to Thy1 (r = 0.65), a recognized RGC marker. Immunofluorescence experiments confirm that in the young and adult mouse retina, Chrna6 is preferentially expressed by RGCs. We further show that C3H/HeJ retinas, which lack photoreceptors, also express Chrna6 in the RGC layer. Gene expression array analyses, confirmed by RT-PCR, show progressive loss of Chrna6 expression in retinas of the DBA/2J glaucomatous mouse retinas.

Conclusions: Quantitative trait locus analysis provides support for Chrna6 as a RGC marker. Chrna6 expression decreases with death of RGCs in glaucomatous DBA/2J mice and after optic nerve crush injury, further supporting Chrna6 as a reliable RGC marker. High expression of RGC Chrna6 in the absence of photoreceptors is suggestive that Chrna6 expression by RGCs is independent of photoreceptor-derived stimuli.

KEYWORDS::

• Aging
• Glaucoma
• Neurodegenerative Diseases
• Retina
• Gene Network
• QTL

ACKNOWLEDGEMENTS

We would like to thank Nicklaus P. Atria, Frederick A. Kweh and Amit K. Patel for their contribution to this manuscript.

Declaration of interest: RKL was supported by NIH NEI grant EY016775. The Bascom Palmer Eye Institute is supported by an unrestricted research grant from Research to Prevent Blindness and NIH center grant EY014801. SKB is supported by NIH NEI grant EY016112 and a Research to Prevent Blindness Career Award. EEG is supported by NEI grant RO1EY017841 and an unrestricted grant from Research to Prevent Blindness to the Hamilton Eye Institute, University of Tennessee.