Transcriptomic profiles of retinal ganglion cells are defined by the magnitude of intraocular pressure elevation in adult mice

Elevated intraocular pressure (IOP) is the major risk factor for glaucoma, a sight threatening disease of retinal ganglion cells (RGCs) and their axons.  Despite the central importance of IOP, details of the impact of IOP elevation on RGC gene expression remain elusive.  We developed a novel 4-step immunopanning protocol to extract adult mouse RGCs with high fidelity and used it to isolate RGCs from wild type mice exposed to 2 weeks of IOP elevation generated by the microbead model.  IOP was elevated to 2 distinct levels which were defined as Mild (IOP increase >1mmHg and <4mmHg) and Moderate (IOP increase > 4mmHg).  RNA sequencing was used to compare the transcriptional environment at each IOP level.  Differentially expressed genes were markedly different between the 2 groups, and pathway analysis revealed frequently opposed responses between the IOP levels.  These results suggest that the magnitude of IOP elevation has a critical impact on RGC transcriptional changes.  Furthermore, it is possible that an IOP-based set point exists within RGCs to impact the direction of transcriptional change.  It is possible that this improved understanding of changes in RGC gene expression can ultimately lead to novel diagnostics and therapeutics for glaucoma. RGC mRNA profiles of 6 week old C57BL/6J mice injected with two levels of elevated IOP pressure induced by microbeads. Samples were pooled and split into tripicates. Trancriptomes were generated by deep sequencing, using Illumina HiSeq2500.